corresponding author: email: nebhawas@gmail.com, phone +251-910-248878 public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia keywords: active abattoir survey; cysticercus bovis; dilla town; taeniasis; questionnaire survey introduction bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al., 2007). taenia infection in human is referred to as taeniasis and the one caused by the larval stage is referred to be cysticercosis (hancock et al., 1989). bovine cysticercosis, caused by the metacestodes of t. saginata, is distributed worldwide occurring in developed as well as developing countries (dorny et al., 2009). however, the prevalence of this parasite is considered to be higher in developing countries. this phenomenon is related to poor sanitation, traditional cattle husbandry systems and inadequate meat inspection facilities (cabaret et al., 2002; dorny and praet, 2007).the life cycle and transmission of parasite occurs most commonly in environments characterized by poor sanitation, primitive livestock husbandry practices and inadequate meat inspection, management and control policies (mann, 1983; phiri et al., 2003). humans are the obligate final host and become infected by ingesting infected meat that has been inadequately cooked or frozen (scandrett et al., 2009). most incidents arise in cattle as a result of direct exposure to proglottids shed east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx east afr. j. biophys. comput. sci., vol. 1, issue. 1 54 research article a cross sectional study was conducted during november 2013 to june 2014 to estimate the prevalence of cysticercosis from abattoir survey and taeniasis within the society found in and around dilla town. active abattoir survey and questionnaire survey were performed to accomplish the study. of the total of 400 inspected cattle carcasses, 17 had varying number of c. bovis giving an overall prevalence of 4.25% (17/400). anatomical distribution of the cyst showed that highest proportions of c. bovis cyst were observed in shoulder muscle and tongue (29.41%), followed by, masseter muscle (23.53%), heart (11.76%) and liver (5.88%). of the total 69 interviewed respondents, 57.79% (40/69) had contracted t.saginata infection. the majority of the respondent had an experience of raw meat consumption (65.29%, 45/69) as a result of traditional and cultural practice. from those raw meat consumers, 62.2% (28/45) were experienced taeniasis. however, no significant association was observed between raw meat consumption and taeniasis (p<0.05). the findings of this study including prevalence of c. bovis and questionnaire survey of taeniasis prevalence indicated the importance of cysticercosis and taeniasis in public health aspects. therefore, due attention should be given to the public awareness and strict routine meat inspection in order to safe guard the public health. abstract mailto:nebhawas@gmail.com east afr. j. biophys. comput. sci., vol. 1, issue 1 from humans, but there have been some reports of large scale outbreaks resulting from sewagecontaminated feed or forage. even in developed countries where high standard of abattoir meat inspection that identify measly from beef carcass, did not succeeded in eliminating this parasites (frolova, 1982; smith, 1994). generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there is cost related to inspecting meat, the necessity to freeze or boil infected meat and losses may also occur from restriction in exportation of live animal and their products (soulsby, 1982). cysticercosis was significantly more prevalent in between man and animal and the use of causal workers in feedlots may be factors that are conducive to taenia saginata transmission (dorny et al., 2002). in previous studies, taeniasis or bovine cysticercosis is an important meat-borne zoonosis with the impact on the safety of food presented for human consumption in different parts of the country. the reported prevalence of taeniasis in the human population has been found to range from 31.0% to 89.4% in ethiopia (tembo, 2001; abunna et al., 2008; megersa et al., 2010; bedu et al.,2011; endris and negussie, 2011). in ethiopia, the prevalence of bovine cysticercosis ranges from 3.1 % in the central part to 26.25% in the southern part of the country (tembo, 2001; dawit, 2004; nigatu, 2004; hailu, 2005; abunna et al., 2008). high prevalence of cysticercosis is related to the tradition of eating raw beef which is considered one of a major risk factor for its transmission (mamo, 1988). however, there is limitation in terms of countrywide study on prevalence of bovine cysticericosis. although there were some research works carried out with associated factors, there is still little information regarding the recent status of bovine cysticercosis and the prevalence of t. saginata in humans in areas like dilla and its surroundings. therefore, the objective of this study was to estimate the prevalence of cysticercosis in animals and taeniasis in human. materials and methods description of the study area dilla town is currently functioning as an administrative center of the gedeo zone in the southern nations nationalities and peoples region (snnpr) in ethiopia geographically, dilla town is located on 6°24′30′′n longitude and 38°18′30′′e latitude with an average elevation of 1570 meters above sea level. comparatively, the town is located 90 kms from hawassa, the capital of snnpr and 359 kms on the main road from addis ababa to nairobi. dilla is one of the main market centers in southern ethiopia and it is one of the fastest growing urban centers in the country. based on the 2007 population and housing survey of ethiopia, the population of dilla town was estimated to be about 59,150. livestock population of the town was estimated to be 12, 475. the town is covering a total land area of about 1123.4 hectare. the mean atmospheric temperature of the town varies from 20°c in summer to 28°cin winter and the average rain fall is 1257.2mm (csa, 2008). study animals animals which were presented to dilla municipal abattoir mainly come from dilla and 55 east afr. j. biophys. comput. sci., vol. 1, issue 1 the surrounding area (wonago, kura, bore, sonkicha, tunticha and kibre mengist). local zebu cattle and cross breed presented to abattoir for slaughter were used as a study population for active abattoir survey. study type and sample size a cross-sectional study was carried out from november 2013 to june 2014. by following a systematic random sampling method, a total of 400 cattle were randomly sampled and routinely inspected for the presence of t. saginata metacestodes in edible parts of the slaughtered cattle. the total number of cattle required for the study was calculated based on the formula given by thrusfield (2005) for a simple random sampling method. by rule of thumb where there is no information for an area it is possible to take 50% of expected prevalence. using 5% degree of absolute precision, 384 animals need to be sampled but, 400 animals were sampled. study methodology active abattoir survey: active abattoir survey was conducted during routine meat inspection on systematically selected 400 cattle slaughtered at the abattoir. ante-mortem and post-mortem examinations were conducted by visiting the abattoir three days a week. during ante-mortem examination, each study animal was given an identification number and its sex, age and origin was recorded. this is to avoid the unnecessary mixing with organs during inspection. age estimation was done based on owner information and dentition. during inspection, each predilection sites were inspected according to the guideline of ministry of agriculture (1972). questionnaire survey: a semi-structured questionnaire was administered to 69 volunteer respondents from dilla city. in the questionnaire survey, usage of toilet, and raw meat consumption habit were addressed. data management and analysis abattoir data was collected and recorded and the data was carefully entered into microsoft excel. the outcome variable for the abattoir study were cases cysticercus bovis detected during routine post mortem inspection at dilla municipal abattoir. logistic regression was employed to analyze the association of the occurrence with the potential risk factors like sex, origin, breed, age, and body score condition using stata statistical software version 11. multivariate analysis for the risk factors of active abattoir and questionnaire survey during study period was used in which the degree of associations among risk factors was indicated with odds ratio. results abattoir survey prevalence: of the total 400 cattle inspected; 17 cattle were positive for bovine cysticercosis with the prevalence of 4.25. among different risk factors, the proportion of cysticercus bovis was higher in cross-bred (4.34%), medium bcs (4.33%), >9 years old (6.93%), female (9.43%) cattle originated from kibre-mengist (13.3%) places (table 1). table-1: proportions of cysts occurrence in inspected organs and carcass at dilla municipal abattoir during the study period(n=400) 56 east afr. j. biophys. comput. sci., vol. 1, issue 1 variable examined animals positive animals proportions breed local 377 16 4.24 cross 23 1 4.34 bcs medium 346 15 4.33 good 54 2 3.70 age 3 5 year 89 2 2.25 5 9 year 210 8 3.81 >9 year 54 7 6.93 sex male 347 12 3.46 female 53 5 9.43 origin wonago 306 11 3.59 dilla 23 0 0 kura 4 0 0 sonkicha 18 1 5.56 k.meng. 15 2 13.3 bore 16 2 12..5 tunticha 18 1 5.56 anatomical distribution of cysts: analysis of active abattoir survey showed that there was a variation in the infected anatomical distribution of cysticerci in organs inspected. of the organs examined, the highest proportion of c. bovis cysts were observed in the tongue (29.41%) and shoulder muscle (29.41%) followed by masseter muscles (23.53%), heart (11.76%) and liver (5.88%) (table 2). table-2: frequency of anatomical distribution of c.bovis (n=400) organs affected total number of affected organs prevalence proportion within organs tongue 5 1.25 29.41 shoulder muscle 5 1.25 29.41 masseter muscle 4 1 23.53 heart 2 0.5 11.76 liver 1 0.25 5.88 total 17 4.25 100 questionnaire survey: of the total 69 interviewed respondents who participated in this study, 57.97% (40/69) had contracted t. saginata infection. proportion among different factors of respondents were analyzed and showed higher proportion in male (39.13%), >34 years (36.23%), and in those who consume raw meat (40.6%). further analysis showed no significant difference between most of the risk factors (sex, age, meat consumption habit, residence and toilet usage) (p>0.05). however, respondents with college level showed less proportion (5.8%) compared to illiterate (15.94%) with a slight significance difference (p<0.05) (table 3). 57 *corresponding author: email: nebhawas@gmail.com, phone +251-910-248878 table 3proportion of taeniasis among the interviewed respondents in dilla city, southern ethiopia (n=69) variables no of interview (infected) proportion odds ratio (95% ci) p-value sex female 25 (13) 52 1 male 44 (27) 61.36 1.5 (0.46, 5.1) 0.485 age 16 25 16 (7) 43.75 1 25 34 14 (8) 57.14 2.1 (0.35, 13.1) 0.409 >34 39 (25) 64.10 2.9 (0.51, 16.52) 0.228 education level illiterate 18 (11) 61.11 1 primary 21 (14) 66.70 1.1 (0.21, 5.33) 0.939 secondary 18 (11) 61.11 2 (0.27, 15.16) 0.488 college 12 (4) 33.33 10.47 0.052 consumption habit cooked 24 (12) 50 1 raw 45 (28) 62.20 1.5 (0.49, 4.64) 0.473 residence rural 30 (17) 56.70 1 urban 39 (23) 58.97 4.1 (0.7, 24.24) 0.117 toilet usage no 3 (2) 66.67 1 yes 66 (38) 57.58 1.03 (0.07, 14.36) 0.983 total 69 (40) 57.97 discussion the prevalence of c. bovis among the carcasses inspected at dilla municipal abattoir was 4.25% which is in agreement with the findings of tamirat et al. (2018) (4.2%) at bahir dar, ibrahim and zerihun (2012) (3.6%) at addis ababa abattoir, taresa et al.(2011) (3.65%) at jimma, dawit (2004) (4.9%) at gondar, megersa et al. (2010) (4.4%) at jimma and bedu et al. (2011) (3%) at zeway. however, higher prevalence of c.bovis were registered by tegegne et al. (2018) (8.97%) in kombolcha, moje et al. (2014) (10.1%)at shashamanne; abunna et al. (2008) (26.25%) at hawassa; kebede et al. (2009) (7.5%) and regassa et al. (2009) (11.3%) both at wolaita soddo abattoirs. the observed difference among these studies could be explained with the agro-climatic conditions of the study areas, the number of incision made during inspection, the ability of the meat inspector to identify the c.bovis, habit or culture of raw meat consumption, sample size and sampling method, level of environmental contamination with the eggs of t. saginata, dose and viability of egg consumed (scandrett et al., 2009). low infection among the inspected animals in the present study area could be due to limited number of incisions made on the predilections sites. this may in turn lead to missing of infected animals as the sensitivity of detecting the parasite will decline with limited number of incisions (wanzala et al., 2003). the presence and number of cysts in any given site varied greatly among animals and demonstrate the absence of any true predilection sites for c. bovis (scandrett et al., 2009). the present study 58 mailto:nebhawas@gmail.com east afr. j. biophys. comput. sci., vol. 1, issue 1 showed that tongue and shoulder muscle, masseter, heart, and liver were the muscle, predilection sites for the cysts of c. bovis which is similar to the results of megerssa et al. (2010). regarding the anatomical distribution of the cysts, many researchers come up with different results like abunna et al.(2008) and getachew (1990) reported triceps as being frequently affected by the cyst, while mulugeta (1997) found as heart as a preferable organ. however, the present study showed that the most frequently affected organ with the highest number of cysts was the tongue which is in agreement with different studies conducted in different parts of the country (hailu, 2005; bedu et al., 2011). human taeniasis was a widespread health problem in the study area with the prevalence of 57.79% and agrees with the findings of others, 64.2% by taylor et al.(2007), 51.1% by regassa et al.(2008), 56.7% by bedu et al. (2011). however, it was higher than the report from kombolcha (31%) (endris and negussie, 2011). in the current study, significant association were detected between different level of educational level in which respondents with college education showed lower level of taeniasis compared to illiterate (p<0.05). however, the rest of respondents factor including raw meat consumption showed no significant association with taeniasis (p>0.05). this contradicted with different researches that got association between raw meat consumption with taeniasis (abunna et al., 2008; megersa et al., 2010; bedu et al., 2011; endris and negussie, 2011). conclusion & recommendation the recorded prevalence of bovine cysticercosis indicated the importance of this disease in the study area. the finding of this work demonstrates the importance of taenia saginata (taeniasis) and cysticercus bovis in human and animals respectively. the recorded prevalence of cysticercosis was found to be lower as compared to previous findings from different parts of the country. in the study area, the introduction of urban and rural health extension programs that taught the people intensively to use latrine might have a significant role for the reduction of cysticercus bovis prevalence. according to selected respondents, higher proportion of respondents showed infection (taeniasis) at least once in their lifetime. in general, the findings of the present study reflects the circulation of cysticercosis and taeniasis in cattle and human, respectively which deserves serious attention by the various stakeholders in order to safe guard the public health. in this regard different intervention mechanisms like strict meat inspection procedures not to miss the cystic parasite and public education to create awareness on its transmission methods should be implemented. acknowledgements the authors fully acknowledge hawassa university for the financial support and dilla municipal abattoir officials as well as workers for their willingness to support the active abattoir survey. additionally, all peoples that involved in the questionnaire survey were also appreciated. 59 east afr. j. biophys. comput. sci., vol. 1, issue 1 references abunna f., tilahun g., megersa b., regassa a. and kumsa b. 2008. bovine cysticercosis in cattle slaughtered at awassa municipal abattoir, ethiopia: prevalence, cyst viability, distribution and its public health implication. zoonoses public health 55: 82– 88. bedu h., tafess k., shelima b., woldeyohannes d., amare b. and kassu a. 2011. bovine cysticercosis in cattle slaughtered at zeway municipal abattoir: prevalence and its public health importance. j. vet. sci. technol.2: 1–5. cabaret j., bouilhol m. and mage ch. 2002. managing helminths of ruminants in organic farming. vet. res.33 (5):625-640. central statistical authority (csa) 2008. population size and characteristics, snnp statistics, central statistical authority, addis ababa, ethiopia, 8-285. dawit s. 2004. epidemiology of t.saginata taeniasis and cysticercosis in north gondor zone, northwest ethiopia. dvm thesis, faculty of veterinary medicine, addis ababa university, debre zeit, ethiopia. dorny p. and praet n. 2007.taeniasaginata in europe. vet.parasitol. 149:22–24. dorny p., phiri i., gabriel s., spaybroeek n. and verucruysse j. 2002. a sero-epidimiological study of bovine cystcercosis in zambia. vet.parasitol. 104 (3): 211-215. dorny p., praet n., deckers n. and gabriel s. 2009. emerging food-borne parasites, vet. parasitol.163:196–206. endris j. and negussie h. 2011. bovine cysticercosis: prevalence, cyst viability and distribution in cattle slaughtered at kombolcha elfora meat factory, ethiopia.american-eurasian j. agric. & environ. sci.11: 173–176. frolova a.a. 1982. taeniasis control in the usrr. in: lysenko a. 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cysticercosis and human taeniasis: animal–human health and economic approach with treatment trends in kombolcha town, wollo, ethiopia. int. j. one health.4: 15–21. tembo a. 2001. epidemiology of taenia saginata taeniasis and cysticercosis in three selected agro climatic zones in central ethiopia, msc thesis, faculty of veterinary medicine, addis ababa university and free university of berlin. thrusfield m. 2005. veterinary epidemiology, government department of navy, bureau 2nded. uk black well science ltd, pp 182-198. wanzala w., onyango-abuje j., kang`ethe e., zessin k., kyule n., bauman m., ochanda h. and harrison l. 2003. analysis of post-mortem diagnosis of bovine cysticercosis in kenyan cattle. onderstepoort j. vet. res.1 : 28-31. 61 cover v1.pdf (p.1) slide number 1 blank page.pdf (p.2) table of contents vol1.pdf (p.3-5) guideline to authors_ eajbcs.pdf (p.6-14) back cover.pdf (p.15) editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction east east afr. j. biophys. comput. sci. (2022), vol. 3, issue. 2, 1-10 *corresponding author: email: basliel2018@gmail.com, +251 938949495 https://dx.doi.org/10.4314/eajbcs.v3i2.1s phenotypic and allelic distribution of the abo and rhesus blood groups among students at hawassa university, ethiopia mihret a. hailu, wendawek a. mengesha, and zelalem g. tolesa*. department of biology, college of natural and computational sciences, hawassa university, p.o.box 05 keywords: abo blood; allele frequency; ethiopia; phenotypic frequency; rh blood abstract a prior information on the distribution of abo and rh groups is imprtant for management of bld bank and transfusion, genetic counseling, anthropological studies, to study the association of blood groups and diet; to investigate the association between blood and diseases. this study intended to estimate the frequency of abo and rh bloods and investigate gene diversity at both loci among students in ethiopia. a descriptive crosssectional survey was employed involving randomly selected two thousand thirty nine (2039) university students (1054 males and 985 females) with an age range of 18–29 years. blood groups were determined based on agglutination reaction. the most abundant blood group was found to be o (42.47%), followed by a (27.86%), b (21.87%), and ab (7.80 %). the frequency of rh+ and rhwere 90.88% and 9.12 %, respectively. the combined blood types showed o+, a+, b+ and ab+ were: 38.60 %, 25.20%, 20.10% and 7.00%, respectively. slightly different distribution pattern of abo blood group was observed among females from amhara region (o> b> a>ab). the distribution of abo phenotypes from addis ababa and amhara did not differ significantly from those expected under the hardy weinberg equilibrium. a high level of gene diversity was observed for both loci. in general, the o blood type is most frequent and followed by a, b and ab. a similar pattern of distribution of the abo and rh blood groups was found in male and female study subjects. the present study will generate a baseline data that could be used in blood bank management and transfusion, genetic counseling, population genetic and anthropological studies, and for disease management. introduction the knowledge on the distribution of abo and rh groups is important for the management of blood bank and transfusion, genetic counseling, population genetics, and anthropological studies (liu et al., 2017; canizalez-román et al., 2018) and to study the association of blood groups and diet, to relate the association between blood and diseases (puryear, 2017). individuals with the o blood type are thought to be resistant to viral disease (zhao et al., 2021) but susceptible to some bacterial infections (harris et al., 2005) and hepatitis b virus (jing et al., 2020). people with the a blood group have a higher risk, whereas people with blood group o have a east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article mailto:mereba480@gmail.com https://dx.doi.org/10.4314/eajbcs.v3i2.1s east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 1-10 2 lower risk for sars-cov-2 infection and covid-19 severity (zhao et al., 2021). the frequencies of abo and rh blood groups differ with ethnicity, geographical locations, race, population movements, natural selection and genetic drift. in the usa, and mexico the o type is the most frequent, followed by a, b and ab (garratty et al., 2004; canizalez-román et al., 2018). nevertheless, in china (liu et al., 2017), type a is the most common, followed by o, b and ab. in southeast asia, a and b blood groups were interchangeably taking the most common blood group place, while ab was the least common (dewan, 2015). type o is the most frequent whereas ab is less common in most african countries (ndoula et al., 2014; anifowoshe et al., 2017). the frequency of rh blood is less or rare in african and asian countries (anifowoshe et al., 2017; liu et al., 2017). the available limited data indicate that the o blood is more frequent but ab is least common in ethiopia (golassa et al., 2017; fufa and debelo, 2019). to date in ethiopia, there are limited works done on the distribution of abo and rh blood groups and the most are small scale in terms of sample size and regional coverage (golassa et al., 2017; fufa and debelo, 2019). in this work, however, the subjects were originated from almost all regions in the country and relatively bigger sample size of the study subjects involved in the study. therefore, this study intended to eatimate the distribution of abo and rh bloods and investigate gene diversity of both loci among students in ethiopia. it is expected that the data may partly contribute to strategies of supply and demand of blood products in transfusion services countrywide and could have consequences in investigating vulnerability to various disease conditions known to be connected with the blood groups. materials and methods study area and study subjects the study was conducted in four campuses (college of agriculture, main campus, institute of technology and; college of medicine and health sciences) of hawassa university. it is assumed that the regional and ethnic diversity of the ethiopian population could be represented in the university student population. in ethiopia students from different regions are randomly allocated to federal universities in the country, we therefore, believe that, student populations in hawassa university could represent the regional and ethnic diversity in ethiopia. ethiopia has eleven regional states and two city administrations. a descriptive cross-sectional survey was employed involving randomly selected two thousand thirty nine (2039) students (1054 males and 985 females) with an age range of 18–29 years. the selected study subjects originally came from eight regional states (afar, amhara, benishangul gumuz, gambela, oromia, southern nation nationalities and people state (snnprs), somali and tigray) as well as from addis ababa (aa) and dire dawa (the two city administrations). the inclusion criteria for the study were: ethiopian students who are above 18 years old and willing to participate in this study. blood group determination the abo and rh blood group testing was done in the hawassa university students’ clinics, using a commercially available kit for blood east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 1-10 3 grouping (human diagnostic, germany). briefly, blood samples were collected from the tip of volunteers’ finger, a drop of anti-a, anti-b and anti-d human sera was then added into 5% suspension of the collected blood (in principle the red blood cell) in normal saline within test tubes. the mixture was gently stirred with glass rods, and blood groups of the tested individuals were determined based on agglutination reaction. allelic frequency and gene diversity analysis the frequencies of the ia allele (p1), ib allele (p2) and io allele (p3) were calculated based on the extension of hardy-weinberg equilibrium (hwe) for multiple alleles with two codominant allele and one recessive allele (hamilton, 2009). genotypic frequencies were calculated under hwe assumptions as [(p1 + p2 + p3) 2 = p1 2+ p2 2 + p3 2 + 2 p1p2 + 2 p1p3 + 2 p2 p3 = 1]as p1 2 (iaia) + 2 p1p3 (i aio) + p2 2 (ibib) + 2 p2 p3 (ibio) + 2 p1p2 (iaib) + p3 2 (ioio). nevertheless, the rh system alleles “d” and “d” were allocated q1 and q2, respectively, and their occurrences were also computed using hwe for two allele system [(q1 + q2) 2 = q1 2+ 2 q1q2 + q2 2 = 1 ] as q1 2(dd), 2 q1q2 (dd), q2 2 (dd). gene diversity (he) was analyzed according to nei (1973). percentage was used to express blood group phenotypic frequencies whereas allele frequencies were estimated/projected using the assumption of hardy–weinberg equilibrium (hwe). the chi square test was used to compare observed allelic and genotypic frequency distributions of the blood group and rh antigens to that expected under the hwe (hamilton, 2009). the level of statistical significance was at p<0.05. ethical approval the study was carried out after getting ethical approval of the institutinal review bard (irb) of hawassa university (ethiopia), college of natural and computational sciences (ref. no. irb/203/11; date: 05/03/2019). accordingly, the study objectives were explained to students, and written consent for participation in the study was obtained. results distribution of abo and rh blood groups the frequencies of o, a, b and ab blood types among the participants were: 42.47%, 27.86, 21.87% and 7.80, respectively. the o blood group had the highest frequency while blood group ab had the least frequency (table1). the study showed that the abo blood group pattern was in the order of o > a > b > ab. statistically, no significant variation was noted in the proportions of the a, b, o and ab blood groups among the considered regions (χ2 0.05, 12 = 15.055; p < 0.05). but there were slight differences in the frequencies of abo blood types. in terms of each blood type the highest proportion of the a phenotype (30.12%), the b phenotype (25.47%) and o phenotype (44.04%) was observed in snnprs, amhara and addis ababa, respectively (table1). the proportion of abo blood antigens significantly different from those anticipated under hardy–weinberg equilibrium (hwe) (χ2 0.05, 1 = 10.498; p < 0.05) for the combined data set, oromia region (χ2 0.05, 1 = 7.304; p < 0.05), snnprs (χ2 0.05, 1 = 6.027; p < 0.05) and ‘others’ (χ2 0.05, 1 = 4.248; p < 0.05), respectively. however, the distributions in addis ababa (χ2 0.05, 1 = 1.063; p < 0.05) and amhara (χ2 0.05, 1= 0.004, p < 0.05) did not deviate from hwe. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 1-10 4 table1: phenotypic frequency of the abo blood groups and rh system based on regions/ towns regions abo blood rh system n** type a (%) typeb (%) typeab (%) typeo (%) rh + (%) r – (%) addis ababa 234 62(24.50) 52(22.22) 17(7.26) 103(44.04) 202(86.32) 32(13.68) amhara 691 185(26.77) 176(25.47) 44(6.37) 286(41.39) 635(91.90) 56(8.10) oromia 603 167(27.69) 128(21.23) 53(8.79) 255(42.29) 554(91.87) 49(8.13) snnprs 437 132(30.21) 77(17.62) 36(8.22) 192(43.94) 393(89.93) 44(10.07) others * 74 22(28.57) 13(17.57) 9(12.16) 30(40.54) 69(93.24) 5(6.76) total 2039 568 (27.86) 446(21.87) 159(7.80) 866(42.47) 1853(90.88) 186(9.12) *afar(1,1,0,2/3,1), benishangul gumz (1,1,1,5/8,0), dire dewa (1,2,0,1/4,0), gambela (1,1,0,1/3,0), somali (3,2,1,4/7,3)and tigray(15,6,7,17/44,1). numbers in the parenthesis are the numbers of individuals with abo/rh system, respectively. **sample size. the frequency of allele o was larger as compared to alleles a or b (p3>p1>p2). a comparable higher level of gene diversity was found in each region for both loci (table2). table2: allelic frequencies and gene diversity of abo blood group and rh systems region/city abo allele rh allele abo rh abo* rh* p1 p2 p3 q1 q2 he he hs ht dst gst hs ht dst gst aa 0.186 0.16 0.65 0.63 0.37 0.51 0.47 amhara 0.182 0.17 0.64 0.76 0.24 0.52 0.37 oromia 0.203 0.16 0.63 0.72 0.29 0.53 0.41 snnprs 0.215 0.14 0.65 0.68 0.32 0.52 0.43 others 0.238 0.14 0.62 0.74 0.26 0.54 0.39 0.54 0.51 0.04 0.07 0.41 0.42 0.004 0.01 *the figures are for the entire population. he:gene diversity in a subpopulation; hs: average gene diversity within subpopulation; ht: gene diversity for the entire population; dst: gene diversity among subpopulation; gst: gene differentiation among subpopulation; aa; addis ababa; snnprs: southern nation nationalities people regional state the rh+ blood group comprised 90.88% for the overall data set (table 1). the highest frequency of rh+ (93.00%) was observed for ‘other’ group and least was for addis ababa (86.32%). in addis ababa the frequencies of rh+ and rh were 86.32 % and 16.68%, respectively. the largest frequency of q1 allele and lowest level of gene diversity was observed in amhara (table2). the expected gene diversity was highest in addis ababa and the lowest from ‘others’ (table 2). for the abo locus, the highest frequency of gene diversity was observed in the ‘others’ groups (he= 0.535) but the lowest was in addis ababa (he = 0.512). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 1-10 5 the sex specific allele frequency is similar in male and female participants (table3). a unique phenotypic (o > b > a > ab) was observed for females in amhara. table3: phenotypic, allelic frequencies and gene diversity of abo blood based on sexes [male (m); female (f)] regions sexes abo blood type allelic frequencies* n a (%) b (%) ab (%) o (%) p1 p2 p3 he addis ababa m 119 31(26.05) 27(22.68) 7(5.88) 54(45.37) 0.175 0.155 0.670 0.496 f 115 31(26.95) 25(21.73) 10(8.69) 39(33.91) 0.254 0.220 0.526 0.610 amhara m 325 89(27.38) 77(23.69) 22(6.76) 137(42.15) 0.189 0.166 0.645 0.521 f 366 96(26.22) 99(27.04) 22(6.01) 149(40.71) 0.177 0.182 0.641 0525 oromia m 320 86(26.87) 70(21.87) 23(7.18) 141(44.06) 0.188 0.158 0.654 0.512 f 283 81(28.62) 58(20.49) 30(10.60) 114(40.28) 0.220 0.170 0.610 0.551 snnprs m 249 75(30.12) 37(14.85) 21(8.43) 116(46.58) 0.216 0.124 0.660 0502 f 188 57(30.31) 40(21.27) 15(7.97) 76(40.42) 0.214 0.159 0.627 0.536 others m 39 11(28.20) 7(17.94) 4(10.25) 17(43.58) 0.215 0.153 0.632 0.531 f 35 12(34.28) 7(20.00) 4(11.42) 12(34.28) 0.263 0.172 0.565 0.585 total m 1054 292(27.70) 218(20.68) 78(7.40) 466(44.21) 0.194 0.152 0.654 0.512 f 985 276(28.02) 228(23.14) 81(8.22) 400(40.60) 0.201 0.190 0.609 0.553 *sex specific allelic frequencies ab negative case was not observed from addis ababa. the highest frequency for b+ was from amhara while o+ was highest for oromia. the o+ was observed more than one third of the population, while abwas recorded in less than 1% (table 4). table4: phenotypic frequencies of abo blood types based on the rh system regions/town n* phenotype (%) a+ ab+ bab+ abo+ o addis ababa 234 52(22.22) 10(4.27) 50(21.4) 2(0.85) 17(7.30) 0(0.00) 83(35.47) 20(8.54) amhara 691 171(24.70) 14(2.00) 159(23.00) 17(2.5) 40(5.80) 4(0.60) 265(38.40) 21(3.00) oromia 603 150(24.9) 17(2.8) 117(19.4) 11(1.80) 48(8.00) 5(0.80) 239(39.40) 16(2.70) snnprs 437 120(27.50) 12(2.70) 71(16.20) 6(1.40) 30(6.90) 6(1.40) 172(39.40) 20(4.60) others 74 21(28.37) 1(1.35) 12(16.23) 1(1.35) 8(10.81) 1(1.35) 28(37.33) 2(2.70) total 2039 514(25.20) 54(2.60) 409(20.10) 37(1.80) 143(7.00) 16(.80) 787(38.60) 79(3.90) *n: sample size (number of students examined) east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 1-10 6 the proportions of the abo/rh blood groups were significantly different among the five regions (χ2 0.05, 28 = 43.033; p <0.05). there was a clear variation in the frequency distribution of the blood types between males and female subjects among the regions. for instance, the frequency of the a+ and o+ blood type showed a difference between the male and female from addis ababa (table5). table5: phenotypic frequencies of abo blood types based on the rh system for male (m) and female (f) subjects regions/city sex n* phenotype (%) a+ (%) a-(%) b+ (%) b-(%) ab+ (%) ab-(%) o+ (%) o-(%) addis ababa m 119 25(10.70) 6(2.60) 26(21.84) 1(.84) 7(5.88) 0(0.00) 46(38.65) 8(6.72) f 115 27(24.35) 4(3.47) 24(20.86) 1(0.86) 10(8.69) 0(0.00) 37(32.17) 12(10.43) amhara m 325 82(25.23) 7(2.15) 68(20.92) 9(2.76) 21(6.46) 1(0.31) 131(40.31) 6(1.84) f 366 89(24.32) 7(1.91) 91(24.86) 8(2.18) 19(5.19) 3(0.81) 134(36.61) 15(4.10) oromia m 320 80(25.00) 6(1.87) 65(20.31) 5(1.56) 20(6.25) 3(0.93) 131(40.93) 10(3.12) f 283 70(24.73) 11(3.88) 52(18.37) 6(2.12) 28(9.82) 2(0.63) 108(38.16) 6(2.12) snnprs m 249 70(28.11) 5(2.01) 35(14.05) 2(0.80) 18(6.12) 3(1.20) 104(41.76) 12(4.81) f 188 50(26.59) 7(3.72) 36(19.15) 4(2.13) 12(6.38) 3(1.59) 68(36.17) 8(2.25) others m 41 11(26.82) 0(0.00) 7(17.07) 0(0.00) 4(9.75) 1(2.43) 17(41.46) 1(2.43) f 33 10(30.30) 1(3.03) 5(15.15) 1(3.03) 4(12.12) 0(0.00) 11(33.33) 1(3.03) total m 1054 268(25.42) 24(2.27) 201(19.07) 17(1.61) 70(6.64) 8(0.76) 428(40.60) 37(3.51) f 985 246(24.97) 30(3.05) 208(21.11) 20(2.03) 73(7.41) 8(0.81) 358(36.34) 42(4.26) *n: sample size (number of students examined) discussion and conclusions distribution of ab and rh bld groups the frequency distribution of abo blood group differs from race to race, population to population and differs in different geographical areas. this study could serve as an initial countrywide report, as the participants were recruited from a national university accepting students from all corner of the country and representing the ethiopian population. ethiopia has a rich cultural, linguistic, and ethnic diversity and is home to over 70 different ethnic groups and over 80 living languages (pagani et al., 2012, 2015). therefore, ethiopia is an important region for studying how genetic diversity and differentiation correlate with linguistic and cultural diversity. furthermore, the knowledge on the distribution of abo and rh groups is important for management of blood bank and transfusion, genetic counseling, population genetics and anthropological studies and to study the association of blood groups and diet, to relate the association between blood and diseases (dewan, 2015; liu et al., 2017; puryear, 2017; canizalez-román et al., 2018). the proportion of ab blood was relatively larger compared to previous studies in ethiopia east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 1-10 7 (tesfaye et al., 2015; fufa and debelo, 2019), this could be due to the wider sampling regions covered in this study (table1). the distribution pattern of abo blood group of females from amhara seems similar to that of the bengali population in bangladesh (dewan, 2015). golassa et al. (2017) found two patterns of abo phenotypes o>a>b>ab [nilotic people] and a>o>b>ab [‘highlanders] in gambela, southwestern ethiopia. the results of this study are similar to that of previous studies in cameroon (ndoula et al., 2014), nigeria (anifowoshe et al., 2017), and mexico (canizalez-román et al., 2018). however, the distribution differs from reports made in egypt (abdelmonem et al., 2019), china (liu et al., 2017), and bangladesh (dewan, 2015). most of the participants in the current study were rh+ (90.88%), while the rest were rh (9.12%). in general, the frequency of rhblood is less or rare in african and asian countries (liu et al., 2017; abdelmonem et al., 2019). golassa et al. (2017), however, reported a relatively higher frequency of rh(19.37%) in gambela, southwestern ethiopia. the overall frequency of rh+ in the current study is comparable to egypt (abdelmonem et al., 2019), whereas lower compared to cameroon (ndoula et al., 2014), and nigeria (anifowoshe et al., 2017). the proportion of rh+ in addis ababa is similar to white non-hispanic in usa (garratty et al., 2004), but large relative to gambela (golassa et al., 2017). the proportion of rhranged from 7-14%, which is wider relative to studies done in ethiopia (tesfaye et al., 2015; fufa and debelo, 2019). such a large range in the proportion of rhin this study could reflect wider regional coverage – the participants are almost from all the regions of the country. the proportions of o+, a+, b+ and ab+ were: 38.60%, 25.20%, 20.10% and 7.00%, respectively. there was variation in the distribution of abo/rh between regions. the proportion of b+ was higher in the amhara but o+ was higher in the oromia (table 4). the o+ frequency was found to be over one third of the entire population, while abwas recorded in less than 1% of the study population. similarly, in cameroon (ndoula et al., 2014), the o+ blood group is highly predominant, representing about half of the entire population, while abis very infrequent. allelic and genotypic diversity the order of the abo allele frequency was io>ia> ib, and similar to earlier studies (ndoula et al., 2014; anifowoshe et al., 2017), but differs from bangladesh (dewan, 2015), and in egypt (abdelmonem et al., 2019).the frequency of q1 allele in this study is lower compared to that of nigeria (anifowoshe et al., 2017). however, a higher level of among subpopulation gene diversity (dst) and gene differentiation (gst) was found to be comparable to mexican populations at both loci (canizalez-román et al., 2018). the higher level of gene diversity supports the hypothesis that ethiopia is an important region for studying how genetic diversity and differentiation correlate with linguistic and cultural diversity (pagani et al., 2012, 2015). the distribution of abo phenotypes for addis ababa city and amhara are not significantly different from those expected under the hwe. if a population is in a hwe the genotypic frequency will remain stable unless the equilibrium is perturbed. that would be a good opportunity for the management of blood banks as the frequencies of the blood groups will be stable east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 1-10 8 generation after generation (ndoula et al., 2014; canizalez-román et al., 2018). participants from different regions showed a similar pattern of distribution for both loci which may reflect the complex processes, population admixing among the regions (hamilton, 2009; dewan, 2015; canizalezromán et al., 2018). although the general pattern of distribution of the abo and rh blood type was similar among different populations, there are also slight differences in the frequencies of different blood types, genotypes and allele frequencies. such differences of in the phenotypic, genotypic and allelic frequencies could be due to differences in the culture, geography, endemic diseases or population admixture (hamilton, 2009; dewan, 2015; canizalez-román et al., 2018). some of these factors could put a selective pressure in favoring one allele over the other and could shape the genetic structure of the abo and rh loci of populations in the respective areas in a long term. furthermore, the low level of gene differentiation observed among subpopulations, could be due to complex population admixture among regions (dewan, 2015; canizalezromán et al., 2018). association between blood groups and diseases the higher frequency of o blood group observed in this study could have an evolutionary advantage in conferring resistance to disease like malaria. in malaria prone countries of africa group o are dominant with the distribution ranging from 40.0% to 80.0 % (cserti and dzik, 2007). as ethiopia is a malaria endemic area in the sub-saharan africa (anstee, 2010; golassa et al. 2017), the dominance of o blood type in the present study, could be advantageous for protection against protozoan diseases (harris et al., 2005; panda et al., 2011). tekeste and petros (2010) reported a strong association between abo blood group distribution and the prevalence of malaria in three malaria endemic areas in ethiopia. the same authors have found among study participants with severe malaria the most frequent blood is type a, whereas among the healthy control groups the most common blood type is o. similarly, a study done by panda et al. (2011) in india found that the most common blood type is b among participant with severe malaria in while blood type o is the most frequent blood type among the healthy control groups. both of these studies support the hypothesis that o blood confers protection to severe malaria albeit the exact mechanism of protection is not well understood and needs further investigation. a review made by rowe et al. (2009) on the association between falciparum malaria and abo blood group support the hypothesis that non-o blood groups emerging as significant risk factors for lifethreatening malaria, through the mechanism of enhanced rosette formation. although the o blood is hypothesized to give protection against malaria, it makes people susceptible vibrio cholera (harris et al., 2005). therefore, this interplay between the different diseases on abo blood type (e.g., cholera vs. malaria) could contribute to the phenomenon of a balanced polymorphism in the human population genetic structure (hamilton, 2009). in a nut shell, the current study established that among the various abo and rh blood groups, blood group o is the most common, followed by blood groups a, b, and ab with a predominance of rh positivity. this work will east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 1-10 9 provide useful information for health institutions in the establishment of regional and national programs that speed up blood transfusions and tissue transplants needed in clinical practice. additionally, this work is expected to generate interest in population geneticists and anthropologists to study genetic variation at abo and rh loci, as well as for physicians interested in the application of immunogenetics in diagnosis and clinical practice. acknowledgements the authors would like to thank all the participants for their cooperation and hawassa university for giving ethical permission to conduct the research and for financial support. references abdelmonem m., fyala a., boraik a., shedid m., mohamed a.h. and abdel-rhman m. 2019. distribution of blood types and abo gene frequencies in egypt. am. j. clin. pathol. 152(1): s153-s153. anifowoshe a.t., owolodun o.a., akinseye k.m., iyiola o.a. and oyeyemi b.f. 2017. gene frequencies of abo and rh blood groups in nigeria: a review. egypt. j. med. hum. genet. 18(3): 205-210. anstee d., 2010. the relationship between blood groups and disease. blood, 115(23): 4635-4643. canizalez-román a, campos-romero a, castro-sánchez j.a., lópez-martínez, m.a., andrade-muñoz f.j., cruz-zamudio c.k.. and flores-villaseñor h. 2018. blood groups distribution and gene diversity of the abo and rh (d) loci in the mexican population. biomed res int ., 2018. cserti c.m. and dzik w.h. 2007. the abo blood group system and plasmodium falciparum malaria. blood, 110:2250–8 dewan g. 2015. comparative frequency and allelic distribution of abo and rh (d) blood groups of major tribal communities of southern bangladesh with general population and their determinants egypt j med hum genet, 16(2): 141-147. fufa a.w. and debelo d.g. 2019. distribution of abo and rh (d) blood groups among students attending secondary and preparatory schools in bote town, oromia national regional state, ethiopia. int. j. sci. technol. educ. res., 10(1): 1-8. garratty g., glynn s.a. and mcentire r. 2004. abo and rh (d) phenotype frequencies of different racial/ethnic groups in the united states. transfusion, 44(5): 703-706. golassa l., tsegaye a., erko b. and mamo h. 2017. high rhesus (rh (d)) negative frequency and ethnicgroup based abo blood group distribution in ethiopia. bmc res notes, 10(1): 1-5. hamilton m. 2009. population genetics. john wiley and sons. harris j.b., khan a.i., larocque r.c., dorer d.j., chowdhury f., faruque a.s. and calderwood s.b. 2005. blood group, immunity, and risk of infection with vibrio cholerae in an area of endemicity. infect. immun. 73(11): 7422-7427. jing w., zhao s., liu j. and liu m. 2020. abo blood groups and hepatitis b virus infection: a systematic review and meta-analysis. bmj open, 10(1). liu j., zhang s., wang q., shen h., zhang y. and liu m. 2017. frequencies and ethnic distribution of abo and rhd blood groups in china: a populationbased cross-sectional study. bmj open, 7(12): e018476. ndoula s.t., noubiap j.j.n., nansseu j.r.n., and wonkam a. 2014. phenotypic and allelic distribution of the abo and r hesus (d) blood groups in the cameroonian population. int j immunogenet ., 41(3): 206-210. nei m. 1973. analysis of gene diversity in subdivided populations. proc. nat. acad. sci., 70(12), 33213323. pagani l., kivisild t., tarekegn a., ekong r., plaster c., romero i.g., ayub q., mehdi s.q., thomas m.g., luiselli d. and bekele e. 2012. ethiopian genetic diversity reveals linguistic stratification and complex influences on the ethiopian gene pool. am j hum genet . 13;91(1):83-96. pagani l., schiffels s., gurdasani d., danecek p., scally a., chen y., xue y., haber m., ekong r., oljira t. and mekonnen e. 2015. tracing the route of modern humans out of africa by using 225 human genome sequences from ethiopians and egyptians. am j hum genet. 96(6):986-91. panda a.k., panda s.k., sahu a.n., tripathy r., ravindran b. and das b.k. 2011. association of abo blood group with severe falciparum malaria in adults: case control study and meta-analysis. malar j, 10(1): 309. puryear d., 2017. the right type of diet: a thesis on the potential relations between your blood type and the way you eat. rowe ja, opi dh, and williams tn., 2009. blood groups and malaria: fresh insights into pathogenesis east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 1-10 10 and identification of targets for intervention. curr opin hematol . 16(6): 480 tekeste z, and petros b., 2010. the abo blood group and plasmodium falciparum malaria in awash, metehara and ziway areas, ethiopia. malar j, 9(1):280. tesfaye k, petros y, and andargie m., 2015. frequency distribution of abo and rh (d) blood group alleles in silte zone, ethiopia. egypt j med hum genet 16(1):71-76. zhao j, yang y, huang h, li d, gu d, lu x, zhang z, liu l, liu t, liu y, he y., 2021 relationship between the abo blood group and the coronavirus disease 2019 (covid-19) susceptibility. clin infect dis. 73(2):328-31. . east east afr. j. biophys. comput. sci. (2022), vol. 3, issue. 2, 48-60 *corresponding author: email: teferi.tademe@wsu.edu.et, +251 10001811 https://dx.doi.org/10.4314/eajbcs.v3i2.5s eyob yishak and teferi tademe dadebo* department of chemistry, college of natural and computational sciences, wolaita sodo university, ethiopia; keywords: adverse effects; faas; medicinal plants; herbal remedies; permissible limits abstract medicinal plants have global applications in the treatment of diverse types of human animal diseases. among the medicinal plants of ethiopia, ocimum lamiifolium hochst. ex benth (damakese, in amharic) is one of the well celebrated and most widely used home remedy for the treatment of a disease locally known as “mitch” which is characterized by headache, fever, inflammation, joint pain, sweat, loss of appetite, etc. the aim of the present study on this medicinal plant was to determine the levels of heavy and trace metals in the leaves using the flame atomic absorption spectrometer (faas), which is nov aa model. the sampling technique used to carry out the analysis was purposive for the community in the selected area use the plant widely to treat different diseases. in addition, for each of three kebeles, selected from duguna fango district, three sites were selected to homogenize the samples. the concentrations or levels of heavy and trace metals, cd, co, pb, cr, cu and zn, in the leaves of the selected medicinal plant were found to be (in mg/l) 0.0489, 0.0579, 0.0936, 0.153, 0.214 and 0.847, respectively. the results revealed that the selected medicinal plant accumulated these metals at different concentration levels in different sites. the results also confirmed that the concentration levels of the metals in the leaves of the selected medicinal plant were not higher than the globally accepted permissible limits. thus, the results indicated that the medicinal plant under the study is safe for medicinal uses. furthermore, monitoring such medicinal plants for heavy and trace metals concentrations is of great importance in protecting the community from the adverse effects of the heavy metals.. introduction background of the study medicinal plants play an important role since prehistoric time as they are used in traditional medicine and also as home remedies. environment, pollution, atmosphere, soil are some of the issues, which play a major role in contamination of medicinal plants by metals and also by microbial growth. traditional medicines include herbal medicines composed of herbs, herbal materials, and finished herbal products, that contain as active ingredient parts of plants, or other plant materials, or combinations of all mentioned (who, 2005). east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx determination of the levels of some selected metals in ocimum lamiifolium in wolaita zone, southern ethiopia research article https://dx.doi.org/10.4314/eajbcs.v3i2.5s east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 49 herbal medicines usually refer to plant-derived substances that occur in nature and are utilized with little or no industrial processing for treatment of illnesses (tilburt and kaptchuk, 2008). herbal medicines are formulated using various parts of plants, including leaves, roots, barks, fruits, and seeds. due to their natural origin, many people who use herbal remedies believe they are safer than conventional pharmaceutical products. the who reckons that over 80% of the population in africa and other developing countries depend on herbal remedies for their healthcare needs (who, 2005). for many people in africa, the high costs of western pharmaceuticals make modern health care services inaccessible. as a result, they heavily rely on herbal medicine and medicinal plants to fulfill their primary health care needs. in addition, western pharmaceuticals are most of the time inaccessible to most people in africa and so herbal medicines have become one of the major options for treating various diseases (debas et al., 2006). when consumed in excess, lead (pb) can increase blood pressure and lead to serious damage to vital organs such as the kidney and the brain. cadmium (cd) poisoning is linked with a number of respiratory disorders, renal failures and cardiovascular issues. although zinc (zn) is an essential mineral, overdosing on it can result in symptoms such as fever, nausea, and general weakness. though iron deficiency causes anemia, too much iron is predominantly dangerous in young children and could cause gastrointestinal and skin problems (baker et al., 2010).therefore, it is necessary to measure and establish the levels of heavy and trace metals in the herbal plants as these elements when consumed at higher levels become toxic. thus, the objective of the present study was to determine the levels of selected heavy and trace metals in the leaves of ocimum lamiifolium plant using flame atomic absorption spectrophotometer statement of the problem the use of herbal medicines is rapidly expanding around the world. many individuals now turn to herbal medicines or associated products for their healthcare within various national healthcare systems. however, mass media coverage of adverse events is often exaggerated, leading to the negative perceptions of herbal medicines in general, rather than focusing on the specific causes behind these events. currently, most adverse associated with the use of herbal medicines are attributable either to poor product quality or the improper usage. in order to expand knowledge about genuine adverse reactions to herbal medicines, and to avoid wasting scarce resources for identifying and analyzing adverse events, events resulting from such situations will need to be reduced or eliminated. ocimum lamiifolium, among vital medicinal plants, is used to treat various ailments such as cough, headache, eye infections, abdominal colic, bloat, inflammation, joint pain, etc. thus, it is used by most people in wolaita zone for the treatment of mentioned diseases. the level of heavy and trace metals in herbal medicines beyond the permissible limit is a matter of great concern to public safety all over the world (khan et al., 2008). the problem is more pronounced in the case of ethiopia because the herbal medicines used by the society without realizing the concentration of toxic heavy metals as well as the trace metals. world health east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 50 organization (who) basically recommends that medicinal plants which form the raw materials for the finished products may be checked for the presence of heavy metals, further it regulates maximum permissible limits of toxic metals like arsenic, cadmium, and lead which amounts to 1.0 ppm, 0.3 ppm and 10 ppm, respectively (who, 2006). the common conception among the population is that “natural” means “safe” and that drugs of natural origin are harmless and have no risk associated with their use, does not match reality. some medicinal plants have inherent toxicity and herbal medicines, like any medicine, have side effects that can cause many diseases (lanini et al., 2009). thus, the current study focuses on the determination of the levels of heavy and trace metals in the leaves of ocimum lamiifolium that is grown in duguna fango district in order to protect the individuals from their adverse effects when used beyond the permissible limits objectives of the study the study was carried out with the objectives of determining the levels of selected heavy and trace metals (lead, cadmium, chromium, cobalt, copper, and zinc) in ocimum lamiifolium using faas technique and comparing the levels of the mentioned metals present in the leaves of ocimum lamiifolium with the permissible limits of who standard and other international standards. significance of the study society has increasing curiosity in the therapeutic use and benefits of herbal remedies. however, there is a wide spread misconception that natural herbs and plants are inherently safe. there is also insufficient information available on the safety of traditional herbs and their products. therefore, this study helps provide important evidence on the levels of selected heavy and trace metals in ocimum lamiifolium grown in the study area so that the society could be free of the potential health risks caused from the excessive uptake of the heavy and trace metals in the herbal medicines. on the other hand, the results of this study could be used as reference for other researchers who want conduct the similar studies on the same plant growing in different parts of the country. scope of the study this study was restricted to the investigation of concentrations of the selected heavy and trace metals found in ocimum lamiifolium grown in duguna fango district, wolaita zone, southern ethiopia using the widely used analytical technique called spectroscopy specifically using the analytical instrument flame atomic absorption spectrophotometer. the metals pb, cd and cr were selected for they are more toxic, and the metals co, cu and zn were selected merely to represent trace elements. furthermore, leaf part of the selected medicinal plant was taken to carry out the analysis for the society use this part of the plant to treat different diseases. materials and methods study area description of the study area the study was conducted in three selected kebeles (the smallest administrative unit) from duguna fango woreda of wolaita zone, which is found in southern nations, nationalities, and peoples regional (snnpr) state. the area is located at 431km south of addis ababa and 82 east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 51 km from hawassa, between 6o40' 7o58'n latitude and 37o4' 37o56'e longitude with a total land area of 46,660 hectares. wolaita zone has 16 woredas (districts) and 3 town administrations. the wolaita people are one of the indigenous people of ethiopia who have their own culture, tradition, political legacy and kingdom. the study area lies at an altitudinal range between 1000 – 2500 meter above sea level and have agro ecologies of dega (high land), woynadega (mid altitude) and kola (low land) with a average annual temperature of l9.5oc and annual rainfall that varies from 7501350mm according to the projected csa final report of 2019. figure 1: the map of ethiopia, snnpr and wolaita zone (adapted from wikipedia) instrument and apparatus heavy and trace metals determination in the leaves of ocimum lamiifolium was done using atomic absorption spectroscopy (aas). flame atomic absorption spectrometer (faas) (germany, novaa) is a suitable technique for determining metals at parts per million (ppm) concentration levels with good precision for many elements. faas offers air-acetylene and/or nitrous oxide flame atomizer. faas technique delivers fast analysis of 10-15s per sample, with very good precision (repeatability), moderate interferences that can be easily corrected, and relatively low cost. as indicated in figure 3, a typical aas consists of radiation (energy) source, atomization compartment, monochromator, detector and data readout system. plant material was sectioned using a stainless steel axe and teflon-coated (ssat) knife, then dried in an air-circulating oven on porcelain supports. samples were subsequently ground and homogenized using a blending device and ceramic pestle and mortar. a digital analytical east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 52 balance was used for accurate sample weighing. microwave digestion was performed in 100 ml round-bottom flasks with ground-glass fittings and reflux condensers (gallenhamp, england). borosilicate volumetric flasks (50, 100, and 250 ml) were employed for sample dilution and the preparation of metal standard solutions. figure 2: basic components of atomic absorption spectrophotometer chemicals and reagents analytical grade chemicals were purchased from sigma-aldrich company found in germany. 69% nitric acid (hno3), 70% perchloric acid (hclo4) and 30% hydrogen peroxide (h2o2) were used for digestion in microwave digester, while multi-element standard solution was used as a reference material. stock standard solution for each metal cadmium (cd), lead (pb), zinc (zn), cobalt (co), chromium (cr) and copper (cu) with a concentration of 1000mg/l was used to prepare intermediate or working standard solutions of 10mg/l for the calibration standards of each metal. throughout the study, deionized water was used. all glass wares were soaked in 5% (v/v) hno3 overnight then rinsed with deionized water and dried using laboratory dryer prior to use. experimental work procedures sample collection and preparation the samples of fresh leaves of ocimum lamiifolium were collected from three different kebeles, which are aruse weyde, edo mazegaja and dendo koysha, in duguna fango district from uncultivated fields. from each kebele, three sites were selected to collect the plant leaves in order to homogenize the sample. samples were placed in plastic bags and labeled, and brought to the laboratory. samples were washed with distilled water, and first air-dried at room temperature and oven was used for further drying and placed in dust free environment; then ground in to fine powder manually using a porcelain mortar and pestle and allowed to pass through a sieve of 0.5mm mesh size. the powdered samples were put in plastic containers and kept in a dry, cool closet until they were analyzed. the plant species was collected from different localities based on its availability and knowledge of the societies regarding its medicinal values of the plant. optimization of the digestion procedure of samples east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 53 achieving optimal sample digestion is essential for accurate analysis. key criteria for optimum digestion include minimal reagent volume and digestion time, a clear solution with minimal residue, low digestion temperature, and procedural simplicity. the digestion procedure was optimized by varying parameters such as reagent volume, digestion temperature, and digestion time. based on visual assessment of the resulting solutions, the optimal and appropriate digestion conditions (table 1), were selected for subsequent faas analysis. sample digestion one gram (1 g) of each powdered sample was accurately weighed using a calibrated digital analytical balance and transferred into a 250 ml beaker. to each sample, an optimized mixture of 69% concentrated nitric acid (hno3), 70% perchloric acid (hclo4), and 30% hydrogen peroxide (h2o2) was added, following the optimized digestion procedure. after cooling for 30 minutes, distilled deionized water was added to dissolve any precipitate, followed by gentle swirling. the resulting solution was filtered into a 50 ml volumetric flask using whatman filter paper number 41 to remove any suspended matter. the filter paper was subsequently rinsed with distilled deionized water until the volume reached the mark. each bulk sample was processed in triplicate. the digested and diluted sample solutions were then stored in plastic sample bottles for faas analysis. chemical analysis instrument operating conditions intermediate standard solutions (10 mg/l) were prepared from 1000 mg/l atomic absorption spectroscopy (aas) stock solutions. these intermediate standards were further diluted using distilled deionized water to create five working standards for each target metal. flame atomic absorption spectrophotometry (faas), equipped with a deuterium arc background corrector and an air-acetylene flame system, was used to analyze six metals. an external calibration curve was used for quantification, and all instrument parameters (burner and lamp alignment, slit width, and wavelength) were optimized for maximum signal intensity. aas is a quantitative method that measures the concentration of the element by passing light in specific wave length emitted by a radiation source of a particular element through cloud of atoms from a sample. atoms absorbed light from an energy source known as hollow cathode lamp (hcl). in faas, the reduction in light intensity reaching the detector is directly proportional to the concentration of the target element in the original sample. a typical faas instrument consists of a light source, a sample atomizer, a monochromator, a detector, and a data processing system. three replicate measurements were performed for each sample. the hollow cathode lamp for each metal was operated at the manufacturer’s recommended conditions, using the respective primary source line for analysis. acetylene and air flow rates were carefully controlled to ensure optimal flame conditions. the absorption mode of the instrument was used to analyze all six target metals (pb, zn, cu, co, cr, and cd). instrument calibration calibration curves were cautiously prepared to determine the concentration of the metals in the sample solution. before the commencement of the experiment, the instrument (i.e. flame atomic absorption spectrometer [faas]), was east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 54 standardized using five series of working standards. the working standard solution of each metal was prepared from the 10 mg/l intermediate standard solutions of their respective metals. wavelengths, concentration of the intermediate standards, working standard solutions and the correlation coefficients of the calibration curve for each of the metals were identified and presented (table 4). method detection limits (mdl) the method detection limit (mdl), also known as the limit of detection (lod), represents the minimum concentration of an analyte that can be reliably detected by an analytical method with a specified level of confidence. the limit is statistically determined as the lowest possible concentration distinguishable from a blank, typically with 95% confidence. the mdl/lod is often defined as the point where the signal-tonoise ratio exceeds 3, but is not necessarily a precisely quantified value. it can be calculated by multiplying the standard deviation of the reagent blank (sblank) by three: mdl = 3 × sblank (chen, 2007). method validation method validation is essential to confirm that an analytical method is suitable for its intended purpose. given the lack of certified reference materials for the leaf and seed samples, the efficiency of the optimized digestion procedure was assessed by spiking 1 g ocimum lamiifolium leaf samples with known concentrations of each target metal. percentage recovery, a crucial parameter for method validation, was calculated by comparing the measured concentrations in spiked and nonspiked samples, which were digested and analyzed under identical conditions. then the percentage recovery of the analyte was calculated by: percentage recovery = x 100% where, cm = concentration of metal of interest (adapted from: ijrpc (2014), 4(1), 202-216) statistical analysis all measurements were done in triplicates and expressed as mean ± standard deviations. data was analyzed using analysis of variance (anova) at level of 5% (p≤ 0.05) followed by least significant difference post hoctest in microsoft excel for the determination of statistical significance of a given metal across the samples, not within a given sample. data was further manipulated with origin pro 2020b sroh(1) for windows version software program. results and discussion optimization of working procedures as indicated in table 1 below, eight optimization procedures were used to get the optimum digestion conditions. the procedures used in steps one through four were not chosen as optimum conditions for they used maximum reagent volumes and the highest digestion temperature as well as long time even if some of the procedures gave clear and colourless solutions. in steps six up to eight, the volumes of reagents were relatively low, but they took place at relatively long times. therefore, procedure five was chosen as optimum condition for the digestion, because it took place at relatively minimum reagent volumes, low digestion time to give clear and colorless east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 55 solution. table1: methods tested during optimization of the digestion procedure for the samples of the leaves of ocimum lamiifolium. no. wt. (g) volume of reagents (ml) max. temp. (oc) time (min) results hno3 hclo4 total 1 1.0 4 3 7 200 60 clear but turbid 2 1.0 5 2 7 200 60 clear but yellowish 3 1.0 5 1 6 200 60 clear but pale yellow 4 1.0 3 2 5 200 10 clear and colourless 5 1.0* 3* 2* 5* 150* 20* clear and colourless 6 1.0 3 2 5 140 60 clear and colourless 7 1.0 4 1 5 130 40 clear and light yellow 8 1.0 3 2 5 140 30 clear and light yellow *optimum digestion conditions the results of the analytical recovery test the validation of the method was tested by spiking the samples with a standard of known concentration of the analyte metals. as depicted in table 2 below, the results indicated that the concentrations of elements determined are in agreement within the acceptable range for all metals, that is 80-120%. hence, the digestion method was efficient because the values of the percentage recoveries lied within the acceptable range. table2: analytical recvery results btained for the validation of the ptimized procedure of plant samples. instrument operating conditions the operating conditions for the instrument were prepared for each metal at an appropriate wave length, slit width, current and idl (table 3). intermediate standard solutions of 10mg/l were prepared using 100 ml flask from stock standard solution that contained 1000 mg/l of soluble salts of cd(no3)2, pb(no3)2, co(no3)2, zn(no3)2, cu(no3)2 and oxide of chromium for each metal of interest. mdl was calculated by metal concentration in nonspiked sample (mg/l) amount added (mg/l) concentration in spiked sample (mg/l) percentage recovery (%) cd 0.05 0.03 0.08±0.01 100±0.025 co 0.06 0.04 0.095±0.01 87.5±0.028 cr 0.15 0.14 0.28±0.007 92.9±0.078 cu 0.21 0.19 0.39±0.01 94.7±0.11 pb 0.09 0.08 0.17±0.007 100±0.049 zn 0.85 0.82 1.68±0.02 101±0.49 east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 56 multiplying the standard deviation of blank solution by three (mdl = 3sblank). table3: instrument operating conditions for the analysis of metals in the samples of selected plant. element wavelength (nm) slit width (nm) current (ma) idl* (mg/kg) cd 228.80 0.70 2.00 0.0001 zn 213.90 0.70 2.00 0.0001 cu 324.80 0.70 2.50 0.0001 co 240.70 0.20 5.00 0.00075 cr 357.90 0.70 4.04 0.00005 pb 283.3 0.7 2 0.003 *instrument detection limit concentrations of working standard solutions and correlation coefficients of calibration curves working standard solutions were prepared from intermediate standard solutions containing 10mg/l, which was prepared from stock standard solutions, by diluting with deionized water to obtain five working standards for each metal of interest as indicated in table 4. the table also showed that the correlation coefficients of calibration curves of all six metals were closer to one. thus, these results confirmed that there are strong linear relationships between two variables, which are absorbance and the concentrations of working standard solutions. table4: cncentrations of working standard solutions and crrelation cefficients of the calibration curves for the analysis of plant samples. metal concentrations of working standard solution correlation coefficient cd 0.5, 1.0, 1.5, 2.0, 2.5 0.999 co 0.1, 0.5, 1.0, 1.5, 2.0 0.9989 cr 0.5, 1.0, 1.5, 2.0, 2.5 0.9988 cu 0.1, 0.5, 1.0, 1.5, 2.0 0.9977 pb 0.5, 1.0, 1.5, 2.0, 2.5 0.9959 zn 0.5, 1.0, 1.5, 2, 2.5 0.9974 east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 57 the determination of heavy and trace metals in ocimum lamiifolium as indicated in table 5, all six metals (cd, pb, co, cr, cu, zn) were detected in all samples of the selected medicinal plant with variable concentrations in the sites. the results revealed that the concentration of zinc was the highest and that of cadmium was the least of all the metals. furthermore, the results revealed that there were variable concentrations of each analyte metal in the selected sites. concentration trends of metals in dendo koysha as depicted in table 5, zinc had the highest concentration among the metals and the metal with the next highest concentration was copper. the fact that zinc had the highest concentration among these metals was also true in other herbal medicinal plants based on different literatures (baye and haymete, 2010). but, cadmium and cobalt had the same concentration, which is 0.04 mg/l; similarly chromium and lead had the same concentration, that is, 0.10 mg/l. concentration trends of metals in aruse weyde the concentration of the metals in this sample site varied from 0.05 to 0.78 mg/l. the metal with the highest concentration and the one with the least concentration were zinc and cadmium, respectively. the concentrations of co, cr, cu and pb were 0.06, 0.18, 0.25, and 0.08, respectively (table 5). the concentrations of the selected metals varied in different sites may be due to the difference in soil types, ecological locations, etc. (ambaye and mussa s., 2015). concentration trends of metals in edo mazegaja based on the results given on table 5, the concentrations of the metals varied from 0.05 to 0.54 mg/l. though the concentrations differed from the other sample sites in this study, the metals with the highest and the least concentrations were zinc and cadmium, respectively. the concentration of co, cr, cu and pb were 0.07, 0.17, 0.19 and 0.10, respectively. here, also the concentration differences of the selected metals from the other sites were observed due to the variation of different factors like ecological locations. comparison of the concentration of each metal among the sample sites and with different permissible limits cadmium as indicated in table 5, the concentration of cadmium ranges from 0.04 mg/l to 0.05 mg/l. this result showed that there was no such much difference in the concentration of cd in all the sites selected. other literatures showed that the concentration of cadmium in other herbal medicines varied between 0.0045 mg/l and 0.0091 mg/l; for instance, in champion leaf, its concentration was 0.0068 ppm (baye and haymete, 2010). however, the concentration of cadmium in the study area was well below the permissible limit set by who and other organizations. the permissible limit of cadmium in medicinal plants set by who, china and thailand, was 0.3 mg/l, which is equivalent to 0.3 mg/l (fao/who, 2006). the literatures suggested that it is safe for consumption if its level is less or equals to this permissible limit. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 58 cobalt the concentration of cobalt in the studied medicinal plant ranges from 0.04 mg/l to 0.07 mg/l. this result indicated that there was variation in the concentration of cobalt in the sample sites. however, the difference in the concentration is not such much great. for herbal plants, the who/fao has not set any regulation limit for cobalt. but, according to jabeen et al. (2010) the concentration of cobalt in different plant samples ranges from 0.18 to 0.4 mg/l 9. thus, the obtained result of cobalt is not greater than these results. chromium as depicted in table 5, the concentration of chromium ranges from 0.10 mg/l to 0.18 mg/l. this range indicated that there was a concentration variation of chromium in different sites of the selected area. the research done on the heavy metal analysis of seven herbal medicines reported that the concentration of chromium ranges from 0.04 ppm to 0.20 ppm (baye and haymete, 2010). so, these values are comparable with the concentrations of chromium in the current study. the permissible limit for chromium in herbal medicinal plants has not been set by the who yet. however, 2.0 ppm was set by canada as the permissible limit of chromium in raw medicinal plant. high intake of chromium is reported to have a toxic effect, causing skin rash, kidney and liver damage, cancer of the lungs and nose irritations (khan et al., 2008). copper as indicated in table 5, the concentration of copper varied between 0.19 mg/l and 0.25mg/l. this result indicated that there is a concentration difference of the metal in different sites which may be related with different factors like soil type difference. regulatory limits for copper in herbal medicines have not yet been established by the who/fao however, china and singapore in 2008 set the permissible limits of 20 mg/land 150 mg/l, respectively (jabeen et al., 2010). thus, the concentration of copper in the studied medicinal plant was well below than these limits. lead the results in table 5 showed that the concentration of lead in the study area varied between 0.08 mg/l and 0.1 mg/l. from this, it is obvious that there was almost uniform pattern in the distribution of lead. the concentrations of lead varied between 0.02 mg/l and 0.09 mg/l in other medicinal herbs as indicated in the report of the journal of scientific and engineering research, 2016, 3(2). so, the result of lead in the present study was approximately equals to the above values. the who (2006), malaysia, china and thailand (2008) set the permissible limit for lead in medicinal herbs as 10 mg/l (khan et al., 2008). so, the results of the study area showed that the concentration of lead was well below the permissible limit. zinc table 5 indicated that the concentration of zinc in the study area ranges from 0.54 mg/l to 1.21 mg/l. when compared to the variation in the concentration of other metals, the difference is great in the case of zinc as well as its concentration was high. the permissible limit for zinc in herbal medicines set by who/fao is 50 mg/l. though there is little information east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 59 about its toxicity, consumption of zinc beyond the permissible limit may result in toxic effect on the immune system (waheed and fatima, 2013). the concentration of zinc in the studied medicinal plant was very much below than this value. table5: mean cncentrations of metals (mg/l) in the studied medicinal plant in the samples cllected from different sites. metals concentrations of metals in three sites (mg/l) mean±sd dendo koysha aruse weyde edo mazegaja cd 0.04 ± 0.01 0.05 ± 0.01 0.05 ± 0.01 co 0.04 ± 0.01 0.06 ± 0.00 0.07 ± 0.01 cr 0.10 ± 0.01 0.18 ± 0.03 0.17 ± 0.02 cu 0.20 ± 0.02 0.25 ± 0.01 0.19 ± 0.00 pb 0.10 ± 0.01 0.08 ± 0.02 0.10 ± 0.06 zn 1.21 ± 0.13 0.78 ± 0.06 0.54 ± 0.06 conclusion the contamination of herbal medicines is due to the accumulation of the metals in different parts of the medicinal plants. hence, the concentrations of the metals should be measured in order to be free of their toxic effects. in the present study, the analysis of heavy and trace metals in the selected medicinal plant was made by using faas by following the optimized digestion method. the digestion method was optimized by changing the parameters until clear and colourless solution was obtained. the concentrations of all the selected metals in the medicinal plant, ocimum lamiifolium, were determined. the concentrations of zn, cu, cr, pb, co and cd are 0.847, 0.214, 0.153, 0.0936, 0.0579 and 0.0489, respectively. in the studied area, the concentration of zinc was the highest of all the metals. however, its concentration was not above internationally accepted permissible limits. in the medicinal plant under study, the concentrations of some metals were below and that of others were nearly equal to internationally accepted permissible limits so that this showed the plant is safe for medicinal uses. furthermore, the efficiency of the digestion method was confirmed by percentage recoveries which were within accepted ranges, that is, 80 – 120%. acknowledgement first and for most the author would like to glorify almighty god. the author also acknowledge wolaita sodo university, ethiopia for financial support and cooperation in this research work. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 48-60 60 references ambaye t.g. and mussa s. 2015. in vitro antimicrobial efficacy of fractions from ocimum lamifollium leaves extrct. nat prod chem res 3:6 196. doi:10.4172/2329-6836.1000196 baker r.d., greer f.r. and committee on nutrition. (2010). diagnosis and prevention of iron deficiency and iron-deficiency anemia in infants and young children (0–3 years of age). pediatrics, 126(5), 1040-1050. baye h. and hymete a. 2010. lead and cadmium accumulation in medicinal plants collected from environmentally different sites. bull environ contam toxicol. 84: 197-201. chen k., jiao j.j., huang j. and huang r. 2007. multivariate statistical evaluation of trace elements in groundwater in a coastal area in shenzhen, china. environ. pollut. 147(3): 771-780 csa (central statistics agency) 2019. final report the federal democratic republic of ethiopia central statistical agency, ethiopia debas h.t. 2006. the problem of heavy reliance on international medical graduates to supply the surgical workforce in the united states. surgery 140 (3): 359-361. jabeen s., shah m.t., khan s. and hayat m.q. 2010. determination of major and trace elements in ten important folk therapeutic plants of haripur basin, pakistan. j. med. plant. res. 4(7): 559-566. khan a., khan l., hussain i., marwat k. and akhtar n., 2008. profile of heavy metals in selected medicinal plants. pak. j. weed sci. res. 14(2): 101-110 khan s.a., khan l., hussain i., marwat k.b. and 3 and akhtar n. 2008. profile of heavy metals in selected medicinal plants. pak. j. weed sci. res 14 (2): 101110. lanini j., duarte-almeida j.m., nappo s. and carlini e. a. 2009. what comes from the earth does not hurt: reports of problems related to the use of medicinal plants by roots of diadema/sp. brazilian journal of pharmacognosy 19: 121-129. tilburt j.c. and kaptchuk t.j. 2008. herbal medicine research and global health: an ethical analysis. bull. world health organ. 86: 594-599. waheed s. and fatima i. 2013. instrumental neutron activation analysis of emblica officinalis, terminalia belerica and terminalia chebula for trace element efficacy and safety. appl radiat isot. 77: 139-144. who 2005. quality control methods for medicinal plant materials, revised, geneva. who 2006.the world health report 2006: working together for health. world health organization . *corresponding author: email: drpnatarajan123@gmail.com, phone +251969-454307 distribution of aeromonas bacterial population in water, sediment and nile tilapia in fish culture pond, guder, ethiopia bekele lema1, p. natarajan2*, kassaye balkew workagegn2 and zufan bedewi3 1department of biology, ambo university. ambo, ethiopia 2department of aquatic sciences, fishery and aquaculture, , college of natural and computational science, hawassa university. hawassa, ethiopia; 3faculty of biological sciences, college of natural and computational science, hawassa university. hawassa, ethiopia; keywords: bacterial population; nile tilapia; water quality; aeromonas bacterial introduction aquaculture is rapidly expanding worldwide, and among different fish species considered for culture, tilapia is favored most because of its suitable cultivable characteristics (suresh and lin, 1992).although tilapia spp. are cultured under diversified aquaculture systems; pond east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx east afr. j. biophys. comput. sci., vol. 1, issue. 1 62 research article abstract assessing heterotrophic bacterial population in water, sediment and fish tissue assumes importance in predicting quality of the fish and water quality in culture system. the present study aimed to estimate the total heterotrophic bacterial population in water, sediment, and nile tilapia (oreochromis niloticus) cultured in an aquaculture farm at guder campus, ambo university, ethiopia. water, sediment and fish body tissue were collected from the fish rearing pond, and were estimated for total heterotrophic bacterial population. various physico-chemical characteristics were recorded following standard methods. the level of bacterial population in water, sediment and fish tissue were done by following standard methods and expressed as colony forming units (cfu) in water per milliliter (cfu ml-1), sediment and fish tissues(cfu g-1).the results revealed more bacterial population in sediment (3.43 x106 to 5.54 x 106 cfu g-1) than in water (1.45x106 to 4.0x106 cfu ml-1) and fish tissues (1.06 ± 1.10x104 to 1.74 ± 10.8x104 cfu g-1in gill filaments; 1.62 ± 11.2x104 to 2.82 ± 13.0x104 cfu g−1 in intestine from; and 0.82 ± 5.9x104 to 1.60 ± 12.1.6x104 cfu g-1; in kidney from 0.48 ± 5.0 to 0.77 ± 4.1x104 cfu g1. in skin). among fish tissues; the heterotrophic bacterial population was more in the intestine than other organs of oreochromis niloticus. in conclusion, the total heterotrophic bacterial population was dominated in sediment than the other samples. the present study concludes that physicochemical characters of water influence the growth and survival of total heterotrophic bacterial population in fish pond. the development of stress due to changes in physicochemical characters of water, and rich nutrient load in pond soil facilitate the growth of pathogenic bacteria which infect the culture fish o. niloticus. the detrivore feeding habits of o. niloticus is responsible for more number of bacterial populations in intestine than in other organs. east afr. j. biophys. comput. sci., vol. 1, issue 1 culture of tilapia is widely practiced in several countries because earthen ponds used for fish culture producenatural fish food organisms due to soil-water interaction. to enhance fish production, fish ponds are excessively fertilized with organic and inorganic fertilizers, and fishes are fed with rich protein diets. this would lead to water quality deterioration when suitable pond management strategies arenot followed to control water quality deterioration. the increased in microbial load in unmanaged ponds reduces health and fish yield potential (groff and lapatra, 2000; karunasagar and otta, 2003). therefore, evaluating microbial load in culture pond is fundamental and significantin aquaculture. among microbes, bacterial pathogens assume importance as they produce great economic loss to aquaculture byproducing severe diseases, epizootics and mass mortality (austin and austin, 1999). environmental changes accelerate bacterial infections (ventura and grizzle, 1987; post, 1989; zorrilla et al., 2003) and that, the rate of infection correspondingly increases with prolonged exposure of fish to stress (sugita et al., 1985) extensive work has been done in certain countries in the field of finfish diseases (ahmed et al., 2004; islam et al., 2008; alyahya et al., 2018). however, except for a very few studies on parasites and bacterial diseases of food fishes (shibru and tadesse,1979; amare, 1986; tefera, 1990; eshetu, 2000), studies on bacterial diseases in fish culture in ethiopia are scarce. as aquaculture has been identified as an important sector to ensure food security in ethiopia, there is an imperative need to address factors that limit aquaculture production. this study focuses on heterotrophic bacterial population in water, sediment and nile tilapia in guder aquaculture farm of ambo university. an assessment of bacterial population in fish and fish culture pond will provide an opportunity to prevent possible disease outbreaks in culture systems. this will also help to evolve suitable remedial measures to control bacterial infections in fish. materials and methods description of the study area the study site, guder aquaculture farm (fig.1) is located in guder town at about 11 km away from the main campus of ambo university. it is located between 1600 and 3192 meter above mean sea level. the rain fall ranges between 800 and 1000 mm and temperature between 10 °c and 29 °c. the soil characteristics are: 48% red soil, 27% black and 25% red and black soil (anon, 2009). the soilis loamy clay, which is suitable for pond construction. regarding weather condition, the woreda has 27% arid, 55% semi-arid, and 18% desert. there are two distinct seasons; the dry season which occurs between october and march followed by a wet period between may and september. the main rainy season is from june to september. the area experiences moderately warm climate which is suitable for fish growth in ponds. the warmest months are from january to may with a peak in february whereas; the cold months extend from june to december. the area of the pond is 300m2 with a depth of 80 cm. the source water for the farm is from endris river which is the tributary of guder river. 63 east afr. j. biophys. comput. sci., vol. 1, issue 1 figure 1. study site: guder aquaculture farm of ambo university enumeration of heterotrophic bacterial population from water, sediment and o. niloticus surface water samples were collected from the earthen pond by using sterilized glass bottles having 250ml capacity from about 20cm below the water surface from four locations of the pond for bacteriological investigation for a period of five months from november to march. similarly the sediment samples were collected from the same location using submerging sterilized glass bottles and were centrifuged for decanting. for gills, intestine, kidney and skin sampling, fifty five nile tilapia with a mean weight of 44.86g were randomly collected from the pond mentioned above. individual fish was killed by a strong blow on the head and then surface disinfection was performed with 70% ethanol before gills, intestine, kidney and skin samples were taken aseptically. later, 1ml of water and 1g of sediment and fish body samples were diluted (101-107 serialdilution factors) using 9ml normal saline solution. from each test tube of each sample, 100µl of sample was speared in duplicate on tryptic soy agree (tsa) plat and incubated at temperature of 37oc for 48 hrs. the concentration of heterotrophic bacterial load at different samples was counted and expressed as colony forming unit per milliliter or gram (cfu/ml or cfu/g) (cole et al., 1988; austin and austin, 1999; pakingking et al., 2015). the plates with 30-300 colonies were used for the determination of bacterial population (prakash and karmagam, 2013). the bacterial colonies were observed according to shape, size, color and opacity (garrity, 2001). all samples for the study were done in duplicate. pure culture of aeromonas bacteria following morphological and colonial characteristics of bacterial on tryptone soy agar (tsa) plates, 3-5 representatives of each colony type were randomly picked from each plate and further sub-cultured to obtained pure cultures of bacterial following the method of monghitcamarin et al. (2020) and pakingking et al. (2020). later, bacterial cultures were stocked in tsa broth containing 15 % glycerol at 80 °c (pakingking et al., 2015). later, 1ml of sample were speared on tryptone soy agar (tsa) plat 64 east afr. j. biophys. comput. sci., vol. 1, issue 1 and incubated at temperature of 37oc for 48hrs for primary isolation and enumeration of total hetrotrophic bacterial following bergey’s manual of systemic bacteriology (holt et al., 1994) using gram-staining and biochemical tests such as oxidase, catalase and indole tests etc. water quality parameters to identify the relationship between water quality parameters and bacterial population during the study period, water temperature, ph and conductivity were measured around 10 a.m. and were determined by thermometer, digital ph meter and portable conductivity cell, respectively. transparency was measured using secchidisc (trivedy and goel, 1984). dissolved oxygen of water sample was analyzed by following winker’s or titration-based on “drop count” method by fixing the samples using alkaline iodide and manganese sulfate and recorded as mg/l (apha, 1998).salinity was measured using portable conductivity meter. ammonia, nitrate, total nitrogen and total phosphorous were measured using calibrated visible uv spectrophotometer in the chemistry laboratory of ambo university. data analysis bacterial density data was transformed into microsoft excel spread sheet before statistical analysis. the means of bacterial load were compared using anova followed by tukey’s post hoc for multiple comparisons. statistical package for social sciences (spss) software version 16.0 windows were used to analyze the data with the level of significance at p<0.05. results and discussion water quality characteristics the results of water quality characteristics are presented in table 1. the results showed that do content of the water varied between the months and it ranged between 6.3 mg/l in december and 7.25 mg/l in february. the water temperature ranged from a minimum of 18.1°c in november and december to a maximum of 24.6°c in february. there is an apparent difference in the water temperature between the months of the study. the lower temperature evidenced during november and december mainly coincided with the intermittent cloudy time which kept the area under cooler condition during this period. the temperature further showed a trend that it increased from january to february and a marginal decline from february to the end of march. moreover, water ph also showed variation between the months. it was slightly acidic in november and december (6.60 6.65), and neutral in february and march (7.50 to 7.6). total dissolved solid concentration was in the range of 186 191 mg/l. chemical parameters like nitrate and phosphates showed marginal fluctuations between 27.1 and 33 and 1.9 and 2.11 respectively indicating the fact that it did not show much variation between the months. the salinity of pond was nil at all times. conductivity values showed an increasing trend till february and showed a slight fall in march. february registered the highest value. chien et al. (1999) reported that high conductivity has a direct bearing on the survival of microbes. pond water transparency ranged from 27.3 to 34.9 cm which is within the desirable level for the culture of tilapia. 65 east afr. j. biophys. comput. sci., vol. 1, issue 1 table1: physiochemical variables of pond water in different months water quality variables nov. dec. jan. feb. mar. water temperature (ºc) 18.1 18.1 22.2 24.6 24.2 ph 6.60 6.65 6.93 7.60 7.50 dissolved oxygen (do) (mg/l) 6.4 6.3 6.9 7.25 7.22 ammonia (nh3) (mg/l) 0.06 0.05 0.07 0.07 0.08 nitrate (no3) (mg/l) 11.21 11.33 11.43 11.42 11.5 phosphate (mg/l) 1.91 1.9 1.91 2.11 2 salinity (g/kg) nil nil nil nil nil total dissolved solids (tds) (ml/l) 186 186 187 191 189 total hardness (as caco3) (ml/l) 79 79 80 79 79 conductivity (µs/cm) 176 181 187 188 185 secchi depth (cm) 27.3 33.1 34.9 34 34 total heterotrophic bacterial (thb) population in water and sediment the results of the quantitative estimation of heterotrophic bacteria in water and sediment of rearing pond in different months are given in table 2. it is evident that the bacterial population varied between the months. total heterotrophic bacterial (thb) population in the sediment ranged from 3.43 x106 to 5.54 x 106 cfu g-1 and in water it ranged between 1.45x106 in november and 4.0x106 cfu ml-1 in january. this finding revealed that bacterial populations were high in january and february and minimum in november in both water and sediment samples. the results also showed that during january and february, there was maximum quantitative heterotrophic bacterial population in earthen pond when compared to november in both water and sediment samples. in the present study, it is clear that physico-chemical parameters alter the microbial environment leading to alteration in microbial community. the factors such as temperature, ph and do when increased, the concentration of bacterial population also increased. this is because increased temperature in warmer months favors the growth of bacteria in the environment (sugita et al., 1985; markosova and jezek, 1994). table2. heterotrophic bacterial population in water and sediment samples months water (cfu ml-1) sediment (cfu g-1) november 1.45x106 3.43x106 december 1.88x106 4.34x106 january 4.00x106 5.00x106 february 3.89x106 5.54x106 march 3.72x106 4.64x106 mean 2.98x106 4.59x106 66 east afr. j. biophys. comput. sci., vol. 1, issue 1 the mean population of bacterial in the sediment samples was 4.59 x 106 cfu g-1 and it was 2.98x106 cfu ml-1 in water, despite the fact that heterotrophic bacterial population was more in the sediment samples and enhances survival of aquatic bacteria than in water. okpokwasili and alapiki (1990) also observed higher bacterial population in fish pond sediment than in water. anon (1997) also reported higher bacterial population density in the sediments than water in general due to the rich organic content of the former and lesser residence time of the microorganisms in the water column than the sediments. heterotrophic bacterial population in different organs of nile tilapia (o. niloticus) the distribution of heterotrophic bacteria in different organs (gills, intestine, kidney and skin) of o. niloticus is presented in table 3. the bacterial population in gill filaments ranged from 1.06 ± 1.10x104 to 1.74 ± 10.8x104 cfu g1; in intestine from 1.62 ± 11.2x104 to 2.82 ± 13.0x104 cfu g−1; in kidney from 0.82 ± 5.9x104 to 1.60±12.1.6x104 cfu g-1; in skin from 0.48 ± 5.0 to 0.77 ± 4.1x104 cfu g-1. each count was the mean value of viable colonies grown on duplicate agar plates made per individual sample. there was no significant difference (p>0.05) during november and december of bacterial count in fish tissues, but significantly increase in february (p<0.05) was observed. this may be related to ambient water temperature. similar observation was reported by ferguson et al. (1996) who reported that change in water parameters have a positive correlation to total heterotrophic bacterial population. pal and das gupta (1992) established that environment could influence the micro flora of the fish and pond system. when bacterial counts of different organs were compared, the count in the month of february was significantly increased (p<0.05) in intestine and gills. in this study, the presence of high bacterial population in the gills and intestine of fish might be due to the high metabolic activity of fish associated with increased feeding rates at higher water temperatures. the bacterial population observed in fish samples was highest in intestine. this may be due to the voracious feeding behavior of tilapia which feeds on detritus, organic matter as reported by beveridge et al. (1988). it is generally presumed that those bacteria which were consumed by fishes like tilapia are particle-bound (bowen, 1976; schroeder, 1978; opuzynski, 1981). next to intestine, higher bacterial load was found in the gills. this is mainly because of the role played by gills in filtering microscopic organisms (hamplet al.,1983). evidences from recent studies of feeding in tilapia suggest that small particles are entrapped among the gill apparatus in a mucous film (drenner et al., 1987; beveridge et al., 1988; northcott and beveridge, 1988). histological studies of the bucco-pharyngeal cavity showed that the mucous cells of the gill rakers produce a highly negatively charged mucous (northcott and beveridge, 1988) which may facilitate flocculation and retain very small particles. next to intestine and gills, the bacterial count was more in kidney. kidney being an excretory organ the bacterial population might have trapped inside the kidney in the process of excretion. skin showed the minimum bacterial load. the reason for minimum load of bacteria in the skin may be due to its frequent contact with the 67 http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2109.2003.00791.x/full#b12 http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2109.2003.00791.x/full#b12 east afr. j. biophys. comput. sci., vol. 1, issue 1 contaminated water and sediment in the aquatic media. table3: monthly mean heterotrophic bacterial population in different organs of fish month gill intestine kidney skin (x104 cfu g-1) (x104 cfu g-1) (x104 cfu g-1) x104 cfu g-1 november 1.06±1.10 1.62±1.12 1.06±1.5 0.76±0.26 december 1.13±1.06 2.03±3.40 1.07±1.3 0.68±0.49 january 1.14±2.10 1.67±1.98 0.82±5.9 0.48±0.50 february 1.49±1.28 2.82±1.30 1.60±1.21 0.77±0.41 march 1.74±1.08 2.36±1.45 1.27±2.26 0.75±0.40 heterotrophic bacterial population in fish, water and sediment based on morphological and biochemical characteristics, bacterial isolates namely escherichia coli, aeromonas, pseudomonas, salmonella, staphylococcus, and streptococcus from fish, water and sediment samples were identified. aeromonas in water and sediments the aeromonas bacterial count in water and sediment is presented in table 4. it ranged from 1.01 x 106 to 1.42 x 106 cfu ml-1and 1.23 x 106 to 1.70 x106 cfug-1 in water and sediment samples, respectively. the bacterial population was more in the sediment (1.47x106 g-1) than in water samples (1.25x106 ml-1). this observation is related to the fact that sediment contains more valuable nutrients for the growth of microorganism than the water column. this has to be ascribed to the sedimentation of the bulk of nutrients added in the form of fish feed or organic wastes for pond fertilization. similar trend was noticed by okpokwasili and alapiki (1990) who related this with the decomposition of these organic adjuncts used for pond water fertilization. furthermore, the favorable temperature and the permissible dissolved oxygen level of the sediment would have enhanced the survival of the bacteria (ogbondeminu, 1993). the bacterial population in the month of january in both water (1.42x106 cfu ml-1) and sediment (1.7x106 cfug-1) followed by february which registered the values as 1.39x106 cfu ml-1 for water and 1.54x106 cfu g-1 for sediments. the bacteria count in the months of november for both water (1.01x106 cfu ml-1) and sediment (1.23x106 cfu g-1) were less when compared to january and february. in general, the occurrences of bacterial population in fish in rearing ponds exhibited variation in relation to different months. it was reported that alteration in environmental parameters influences growth and survival of micro flora in aquatic environment. 68 east afr. j. biophys. comput. sci., vol. 1, issue 1 table – 4: aeromonas bacterial population in water and sediment in different months months water(cfu ml-1106) sediment (cfu g-1106) november 1.01x106 1.23x106 december 1.08x106 1.44x106 january 1.42x106 1.70x106 february 1.39x106 1.54x106 march 1.33x106 1.42x106 mean 1.25x106 1.47x106 relationship between water parameter and aeromonas bacteria the relationship between water quality parameters and aeromonas bacteria in water and sediment in relation to water temperature is presented in table 5. the relationship between physico-chemical parameters and bacterial count attracted much attention (ogbondeminu and adeniji, 1984; ferguson et al., 1996). the results showed that bacterial counts were directly related to the various water variables examined. from november to december when do, water temperature, ph and ammonia were found to be lower, the bacterial population was also lower, and again the bacterial population was higher in january and february. table -5: aeromonas bacteria in relation with water parameters morphological and biochemical characterization of aeromonas bacteria the characteristics recorded are gram’s negative, rod shape with round end and motile (buller, 2004). biochemical properties of aeromonas bacterial isolates are described in table 5. the isolates were positively reacted with cytochrome oxidase, catalase, gas production, and lactose, glucose, and sucrose fermentation and motile whereas the isolates were negative starch hydrolysis. h2s production was positive on motility medium and negative on triple sugar iron agar (tsia). microbiology laboratory guidebook (bonnie et al., 1998) describes the biochemical characteristic of aeromonas bacteria. catalase and oxidase positive and, hydrogen sulfide production on triple sugar iron agar (tsia) negative, and growth temperature tests were conducted to demonstrate the biochemical characteristic of aeromonas bacteria. month do (mg l-1) temperature (0c) ph nh3 (mg l-1) mean aeromonas population (cfu ml-1) water sediment nov.dec. 6.35 18.1 6.62 0.06 1.05x106 1.34x106 jan. feb. 7.07 23.4 7.26 0.07 1.41x106 1.62x106 69 http://www.scialert.net/asci/result.php?searchin=keywords&cat=&ascicat=all&submit=search&keyword=physico-chemical east afr. j. biophys. comput. sci., vol. 1, issue 1 table6. cell morphology and biochemical characteristics of aeromonas spp. test results shape straight, rod, pairs with round end motility test motile gram staining -ve colony color yellowish with opaque hydrogen sulfide test +ve/ -ve oxidase test +ve catalase test +ve starch hydrolysis test -ve gas production +ve lactose/sucrose/glucose fermented +ve acid production +ve triple sugar iron agar acid butt with gas note: result from test conducted +ve indicate positive result conclusion the present study revealed that physicochemical characteristics of water influence the growth and survival of heterotrophic bacterial population in fish culture pond. increased water temperature, favorable dissolved oxygen content and ph facilitate the proliferation of heterotrophic bacterial population in water. excess feed remains, rich nutrient content, organic matter and their longer resident time in pond soil profoundly favor the increase in bacterial count in sediment than water. the development of stress due to changes in physicochemical characteristics of water, and rich nutrient load in pond soil facilitate the growth of pathogenic bacteria which infect the culture fish o. niloticus. the detrivore feeding habits of o. niloticus is responsible for more number of bacterial populations in intestine than in other organs. references ahmed g.u., parveen r. and sultana s. 2004. disease investigation of small indigenous fishes from kailla beel in mymensingh area. j. bangladesh agril. univ. 2(2):305-311. alyahya sa, ameen f, al-niaeem ks, al-sa'adi ba, hadi s, mostafa aa. 2018. histopathological studies of experimental aeromonas hydrophila infection in blue tilapia, oreochromis aureus. saudi j biol sci. 25(1):182-185. amare t. 1986. parasites of fish from lake awassa and chamo. dvm thesis. addis ababa university, faculty of veterinary medicine, debre zeit, ethiopia. anon j. 1997. ecological, toxicological and environmental impact assessment 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addis ababa university faculty of veterinary medicine, debre zeit, ethiopia. toke kutaye woreda, r.d.o. 2009. toke kutaye rural development office annual report. trivedy r.k. and goel p.k. 1984. chemical and biological method for water pollution studies. environmental publications, karad, india, pp 1 22. ventura m.t. and grizzle j.m. 1987. evaluation of portal of entry of aeromonas hydropilla in channel cat fish. aquaculture. 65: 205-214. zorrilla i., chbrillon m., arijo s., diaz-rosales p., martinz-manzanares e., balebona m.c. and marinigo m.a. 2003. bacteria recovered from diseased cultured gillhead sea bream (sparusaurata l.) in southeastern spain. aquaculture. 218: 11 20. 72 cover v1.pdf (p.1) slide number 1 blank page.pdf (p.2) table of contents vol1.pdf (p.3-5) guideline to authors_ eajbcs.pdf (p.6-14) back cover.pdf (p.15) editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction east afr. j. biophys. comput. sci. (2022), vol. 3, issue. 1, 24-42 *corresponding author: email: tamenetadele@gmail.com, +251 916 138218 https://dx.doi.org/10.4314/eajbcs.v3i1.4s landslide hazard assessment and zonation by using slope susceptibility evaluation parameter (ssep) rating schemea case from debre sina, northern ethiopia tamene tadele department of geology, college of natural and computational sciences, hawassa university, p. o. box 05, hawassa, ethiopia keywords: landslide hazard zonation; slope susceptibility; debre sina; landslide triggering; slope facet abstract rainfall-induced landslides of different types and sizes frequently affect the hilly and mountainous terrains of the highlands of ethiopia. the principal aim of the proposed research work was intended to prepare a landslide hazard zonation map of the area, particularly for hazardous zones. in this study, the slope susceptibility evaluation parameter rating scheme has been implemented as a relevant approach to map the landslide hazard of the debresina area, which has experienced slope failure problems for a long period of time. the geology of the area includes quaternary sediments, ignimbrite, rhyolite, different kinds of basalts, and tuff deposits, which are highly weathered and changed into unconsolidated sediments at some localities. locally observed geological structures such as joints, dykes, and other discontinuities have a considerable role in the initiation of landslide hazard. as a general methodology, a facet map was prepared from a topographic map (1:50,000) and rating values were assigned to each causative parameter (both intrinsic and external) based on its severity in triggering landslide hazard. the study area was classified in to three hazard classes, of which 25 % of the slopes fall in to a moderate hazard zone, while 58 % and 17 %were found to be high and very high hazard zones, respectively. authentication of the landslide hazard zonation map with past landslide activities suggests the rationality of the considered leading parameters, the adopted technique, tools, and procedures in developing the study area's landslide hazard map. furthermore, in order to validate the landslide hazard map prepared during the present study, active landslide activities and potential instability areas, delineated through inventory mapping, were overlaid on it, which yielded promising results. introduction the earth’s surface is always in a dynamic change. these changes are more pronounced in mountainous terrains as a result of different mass wasting processes. one of these masswasting processes is landslides (hansen, 1984). according to mohammad et al. (2012), landslide is a slow to rapid downward motion of unbalanced rock and debris masses because of gravity, whereas baeza and corominas (2001), identified landslides occur at a very slow rate, particularly in areas that are very dry and areas that receive sufficient rainfall such that vegetation has stabilized the surface. they may also occur at very high speed, such as in rock slides or landslides, with disastrous consequences, both immediate and delayed, e.g., east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article mailto:tamenetadele@gmail.com https://dx.doi.org/10.4314/eajbcs.v3i1.4s east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 24 resulting from the formation of landslide dams (saro and biswajeet, 2006). depending on techniques applied, activities involved, data analysis, scale of study, and data availability, various landslide hazard-mapping approaches were introduced. barredo et al. (2000) divided these methods into inventory, heuristic, statistical, and deterministic approaches. performing deterministic slope stability analyses demands a considerable amount of time and a deep understanding of both geological and geotechnical factors, coupled with a clear grasp of potential slope failure mechanisms. besides, such analysis techniques may be suitably applied to small areas, at the scale of a single slope only (clerici, 2002; casagli et al., 2004; raghuvanshi et al, 2014). mcclelland et al. (1997) emphasized the heuristic or expertdriven approach, as a method in which a geomorphological expert decides on the type and degree of hazard for each area, using either a direct mapping or indirect mapping approach. this approach is a time consuming and it depends on a large degree on the expertise of the geomorphologist (barredo et al, 2000). the statistical approach compares the spatial distribution of existing landslides in relation to different causative factors (aleotti and chowdhury, 1999). these methods are good for assessing the spatial probability but there are problems in evaluating either temporal probability or the effects of future environmental changes (van westen et al., 2006). the landslide hazard evaluation factor (lhef) technique has been utilized successfully over the years by many researchers but as proposed by raghuvanshi et al. (2014), its major drawback is that it does not account for external causative factors. further, it does not predict for anticipated adverse conditions during construction and performance stage rather it offers stability condition for the slopes only for the existing situations prevailed at the slopes during the time of investigation. in the current study effort is made to overcome the shortcomings of above approaches and thus, a slope susceptibility evaluation parameter (ssep) rating technique, which encompasses both intrinsic and external parameters, has been implemented. landslide problem has been causing lots of casualties, economic and social problems to societies especially to those who are living in the mountainous areas. according to kifle woldearegay (2013), the hilly and mountainous terrains of the highlands of ethiopia are frequently affected by rainfallinduced landslides of different types and sizes. according to gebreslassie (2011), the widespread occurrence of landslides in ethiopia is largely due to a combination of predisposing factors, including rugged morphology, high topography, and the characteristics of outcropping rocks. the triggering factors are essentially connected with the rainfall regime and to a minor extent with seismicity (gebreslassie, 2011). according to asmelash abay and barbieri (2012), debre sina is located along the southwestern afar rift margin, and it was frequently affected by landslides in the past few years. it is bounded by different mountains because of which it has experienced rainfall triggered landslides which endangered the life of people and destroyed public and private properties including various infrastructures. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 25 materials and methods description of the study area location and climate the study area, debre sina, is situated in amhara regional state at a distance of 200 km toward nne of addis ababa, the capital city of ethiopia. geographically, it is bounded between utm coordinates of 582000-593000 me; 1080000-1100000 mn (fig.1). the prevailing climatic condition of the area is "dega" with mean annual rainfall of 1736 mm/year and temperature varying between 10°c to15°c. physiography and the drainage pattern physiographically, the study area is located in the showan highlands, the smallest highlands of the ethiopian northwestern highlands, which also includes the tigrean north central massif, south western highlands of gojam and gondar (leta alemayehu, 2007). the showan plateau is bounded by the ethiopian rift on the eastern and south eastern sides while abay gorge border it on the north western side. the study area generally is characterized by highly variable topographical features which are a reflection of the past geological and erosion processes. the landscape includes plateaus, steep hill slopes, deeply incised valleys and gorges. the elevation of the study area ranges from 1500 m in the southern sector to 3100 m in the northern section. figure 1. location map of the study area. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 26 the drainage system of the area includes many small tributaries feeding the main rivers. most of the tributaries were dry during the present field visit. majority of them, especially small tributaries, arise from high mountains and join the main rivers at the valley floor. the general drainage pattern of the study area is dendritic type as portrayed in (fig.1). geology the paleozoic–mesozoic sediments associated with transgression regression of the sea and cenozoic volcanic rocks which is directly overlying the precambrian metamorphic and mesozoic sedimentary rocks in ethiopia (kazmin, 1973). among these rock units, the geology of the study area and its surroundings can be grouped in to the cenozoic volcanic rocks (fig.2).according to astis et al. (1997), the ethiopian volcanics can be related to two main magmatic stages. the first is the oligocene – pliocene large fissure eruptions of basalts which build up abundant flood lava sequence known as ashange and aiba basaltic formations associated with late ignimbrite sheet (alajirhyolitic formations). figure 2. geological map of the study area. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 27 this magmatic stage ended with the development of large basaltic shield volcanoes, known as the tarmaber formation. however in the recent studies about the continental flood basalts of north-western part of ethiopia, the whole formations were considered as a single unit (hofman et al., 1997; piket al., 1998. recent classification for continental flood basalt of north western part of ethiopia was followed as lower formation, upper formation and the shield volcano. both the lower and upper formation of the continental flood basalt was emplaced 30 my ago within short period of time, less than 1my (hofmann et al., 1997). the central ethiopian highlands exhibit a geological structure consisting of tertiary volcanic rocks capping mesozoic sedimentary rocks, which are visible only in the deep valleys carved by major rivers. examples include: abay gorge, jimma gorge, and mugher gorge. according to mohr and zenitttin (1988), the ashangie formation has been defined by three characteristics: it has experienced a marked dip into the flow sequence of up to 40o; flow thickness averages only about 5m; and individual flows are rarely traceable for more than a few kilometers along strike. mohr and zenitttin (1988), highlighted that the aiba formation is typically composed entirely of massive flood basaltic flows, with or without intervening agglomerate beds. according to gezahegnyirgu (1997), two major phases of magmatic activity took place, which produced different formations. a first phase was responsible for the eruption of lavas that built thick succession, up to nearly two kilometers, of fissural basalts (known as ashange and aiba basaltic formation) and later emplacement of a thick series, up to 500 meters, of silicic lavas mainly in the form of ignimbrite sheets (alaji rhyolite formation). the building up of huge shield-like volcanic complexes followed this fissural magmatic stage from central vents with the predominance of basalts over evolved volcanics (termaber basalt formation). methodology most of the landslide hazard zonation methods are based on the basic assumptions that mass movements are caused by the geological, geomorphic, human induced, etc. factors that can be described through physical parameters, and that the knowledge about these conditions enables drawing conclusions on future landslides (lang et al., 1999). according to anbalagan (1992), landslide susceptibility maps can be constructed by using the relation between each landslide and causative factors. different landslide hazard mapping methodologies in relation to types and scales are portrayed in table 1. 28 types techniques activities characteristics scale d ir ec t in d ir ec t q u a li ta ti v e q u a n ti ta ti v e 1 :1 0 0 ,0 0 0 1 :2 5 ,0 0 0 1 :1 0 ,0 0 0 heuristic geomorphologic analysis use field-expert opinion in zonation x x x x x x mapqualitative combination use expert-based weight values of parameter maps x x x x x statistical statisticalbivariate analysis calculate importance of contributing factor combination x x x multivariate statistical analysis calculate prediction formula from data matrix x x x probabilistic analysis calculate prediction from inventory and time period x x x x deterministic factorsafety analysis apply hydrological and slope stability models x x x inventory remote sensing and field investigations show locations and characteristics of past landslides x x x x landslide hazard evaluation factor (lhef) rating scheme the weight rating system is usually designed in many different ways on the basis of studying the impact of each selected factor, for their importance in inducing the instability. anbalagan (1992), has suggested a landslide hazard evaluation factor (lhef) rating system that incorporates all the causative factors as listed in table 2. the lhef rating scheme may be more relevant as it is based on an empirical approach using important natural contributing factors of slope instability such as; lithology, structure, slope morphometry, land use and land cover, relative relief and hydro-geological conditions. in this scheme, the external factors including rainfall and seismicity have not been included. the maximum weight for individual factor has further been sub-divided into a number of categories to form a detailed lhef rating scheme. this scheme can then be used for calculating total estimated hazard (tehd) for individual facets. the total estimated hazard (tehd) value indicates the net probability of instability of a slope facet. it is calculated slope facet-wise, because adjoining slope facets may have completely different stability situations. the tehd value of an individual slope facet is obtained by summing up the ratings of each causative factor, obtained from the lhef rating scheme for that slope facet. thus, tehd value is equal to the sum of ratings of categories of all causative factors. as depicted in table 2, tehd values are then arbitrarily categorized into different landslide hazard zones. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 table 1. methods of landslide susceptibility mapping in relation to types and scales. 29 s.no causative factors maximum lhef rating 1 lithology 2 2 relationship of structural discontinuities with slope 2 3 slope morphometry 2 4 relative relief 1 5 land use and land cover 2 6 hydrogeological condition 1 total 10 the lhef rating scheme employs an empirical method to evaluate slope instability by considering the individual and combined influences of inherent causative factors. these inherent factors then form the basis for landslide hazard zonation. (lhz) mapping on macro-zonation approach. maximum values of rating for each parameter is awarded keeping in mind its estimated significance in resulting slope failure and also to denote overall field circumstances (table 3). s.no tehd value hazard class 1 <3.5 very low hazard (vlh) 2 3.5-5.0 low hazard (lh) 3 5.1-6.0 moderate hazard (mh) 4 6.1-7.5 high hazard (hh) 5 >7.5 very high hazard (vhh) evaluationsusceptibilitystabilityslope parameter (ssep) rating scheme mappingzonationhazardlandslidethis methodology is a modified technique which is developed by raghuvanshi et al. (2014) and is applicable in large areas demanding rapid slope stability assessment. it mainly relies on field data and produces landslide hazard zonation map by combining both intrinsic and external slope instability triggering parameters. it was developed in order to overcome the shortcomings of anbalagan (1992) lhef rating scheme and is found to be suitable to be applied in present study. the ssep rating technique involves both internal and external activating parameters accountable for slope instability. the slope stability is mainly governed by intrinsic parameters such as; slope geometry, slope material (lithology or soil type), structural table 3. lhz classes on the basis of total estimated hazard (tehd) east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 table 2. maximum lhef rating for causative factors for macro-zonation. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 30 discontinuities, land use and land cover and groundwater (wang and niu, 2009). in addition to the factors mentioned, both natural and human-induced external parameters that contribute to slope instability are also taken into account. the primary natural factors identified as triggers for slope instability include seismic activity (keefer, 2000) and rainfall (collison et al., 2000; dahal et al., 2006). other natural influences that can lead to slope instability, such as snow and avalanches, wind erosion, permafrost conditions, shoreline processes, and volcanic activity, are not considered in the ssep for landslide hazard assessments. manmade activities mainly include constructions and cultivation practices on slopes (wang and niu, 2009). slope facet is defined as a land unit, which is characterized by uniform slope geometry in terms of slope inclination and slope direction (anbalagan, 1992). to demarcate the slope facets, topographic maps were utilized. facet boundaries were delineated using prominent and minor hill ridges, as well as primary and secondary streams, along with other topographical features. for the present study, debre sina topo map of 1:50,000 was utilized to delineate slope facets of the study area. rating values was assigned for each intrinsic and external causative factor based on its severity in landslide initiation and the summation of all causative factors will provide evaluated landslide hazard (elh). finally landslide hazard zonation (lhz) map was prepared based on the facet-wise distribution of elh values. table 4 portrays distribution of higher ssep ratings assigned to each causal factor. triggering parameters maximum rating intrinsic parameters 1. slope geometry relative relief 1 slope morphometry 2 2. slope material 1 3. structural discontinuities 2.5 4. land use land cover 1.5 5. groundwater 2 external parameters 1. seismicity 2 2. rain fall 1.5 3. man-made activities 1.5 total 15 elh= summation of ratings of intrinsic parameters (relative relief + slope morphometry + slope material + structural discontinuity + land use and land cover + groundwater) + summation of ratings of external parameters (rainfall + seismicity + man-made activities) table 4. distribution of maximum ssep ratings assigned to different intrinsic and external factors (source: raghuvanshi et al., 2014) east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 31 results & discussion preparation of facet map for convenience and ease assessment of landslide hazard, the study area has been divided into different slope facets which were defined by major or minor hill ridges, primary and secondary streams, and other topographic waves. according to anbalagan (1992), slope facets are characterized by more or less uniform slope inclination and slope direction. these slope facets were prepared from topographic map of scale 1:50,000 and verified in the field. slope facet was used as base map to award rating values for landslide hazard triggering parameters (table 5). the slope facets were usually delimited by ridges breaks in slope, streams, spurs, gullies and rivers etc. the facet maps form the basis for the preparation of thematic maps in general and ssep mapping in particular and individual facet is the smallest mappable unit. in all 60 facets have been delineated in the study area on the basis of visual interpretation of topographic maps fig. 3a. landslide hazard triggering parameters for landslide hazard zonation, numerical ratings have been assigned to each of the internal and external activating parameters on the basis of their impact towards instability of slope, based on standard ssep rating table. intrinsic parameters intrinsic parameters are considered in hazard mapping because they play a great role in the stability conditions of the slope. these intrinsic parameters are relative relief, slope morphometry, slope material, structural discontinuities, land use and land cover and groundwater (anbalagan, 1992; wang and niu, 2009). based upon the given conditions for each of these internal parameters they may have an effect over the stability condition of the slope. relative relief relative relief is one of the important causative factors which may cause slope instability. it affects the instability condition by increasing the gravitational energy which pulls the slope material down the slope. the relative relief map represents the local relief of maximum height between the ridge top and the valley floor within an individual facet (anbalagan, 1992). relative relief map of the study area has been prepared by taking the altitude difference between hill top and valley bottom within each slope facet which was later processed by arcgis-10.8 software. in the study area 57% of the facets fall in very high relative relief whereas 22% fall in high relief. the remaining facets (21%) fall in medium and moderate relative relief (fig.3d). this implies that more than half of the study area possesses very high relative relief which renders it susceptible to landslide. slope morphometry slope morphometry map of the study area has been designed by calculating the slope angles from topographic map. the ratio of height difference between two points in a given facet to horizontal distance gives decimal value of the slope. by taking the inverse tangent of this value slpes in degrees have been manipulated. these slopes fall in to different slope classes as escarpment/cliff (> 45°), steep slpe (36°-45°), east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 32 moderately steep slpe (26°-35°), gentle slpe (16°-25°) and very gentle slpe (< 15°). later, slope morphometry map of the study area has been prepared by using arcgis-10.8 software. accordingly, 42% of the facets experience moderately steep slope (26°-35°) while 33% fall under gentle slopes. the remaining facets possess steep slopes, escarpment and very gentle slope which account for about 10%, 8% and 7%, respectively. generally, most of the facets have moderately steep slope ranging from 26° to 35°(fig 3e). slope material the rock sub classes in ssep rating system are adopted from classification of rocks based on field estimates of strength by observation which is proposed by (hoek and bray, 1997). thus, slope material is classified as very weak rck (1-5 mpa), weak rck (5-25 mpa), medium strong rck (25-50 mpa), strng rck (50-100 mpa), very strng rck (100-250 mpa) and extremely strng rck (>250 mpa). slope material map of the study area has been prepared from field bservation using l:50,000 scale tpgraphic map as base map (fig. 3f). slope material of the study area is well described by highly weathered and fragmented rock mass that made it difficult to distinguish some rocks from soil during field visit. ignimbrite, alaje basalt and fractured rhyolite are some of the lithologies on which intense weathering was observed. generally, 38% of the study area is covered by medium strength rocks while colluvium materials cover about 27% of it. highly weathered materials and weak rocks each comprise 22% and 13%, respectively. land use land cover land use and land cover pattern is one of the important parameters governing slope stability. vegetation has major role to resist slope movements, particularly for failures with shallow rupture surfaces. a well spreaded network of root system rises the shearing resistance of the slope material because of natural anchoring of slope materials, particularly for soil slopes. moreover, a thick vegetation or grass cover reduces the action of weathering and erosion, hence adds to stability of the slopes. on the other hand, barren or sparsely vegetated slopes are usually exposed to weathering and erosion action, thus rendering it vulnerable to failure (wang and niu, 2009). slope instability is also induced because of anthropogenic activities, i.e., urbanization, particularly on higher slope angles (>300). it not only removes vegetation cover but also adds to the natural weight of the slope as surcharge due to the weight of civil structures. in a hill slope with higher slope angle, buildings are usually located by constructing local cut slopes and flat terraces. with this concept urbanization is broadly classified into three categories (zubair et al., 2012). a sparsely urbanization slope is where construction terraces are located far apart (more than 15 m of horizontal spacing) providing a considerable distance between two terraces along the slope. when we see the areal coverage of land covers in the present study area, bushes and shrubs alone cover 29 % of the study area whereas bare land comprises 23 %. on the other hand heterogeneous agricultural areas, arable land and forest encompass 20 %, 17 % and 11 % of the study area, respectively as shown on fig. 3c. the lulc map of the study area was east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 33 prepared from erdas 9.2 softer and later verified during field visit. groundwater conditions of the study area the susceptibility of rock/ soil to failure is majorly determined by groundwater of an area. hydrological characteristics of an area include underground water conditions, saturation state of rock/soil, presence of streams, rivers, and drainage pattern of the area. water bodies displaced because of presence of interruptions and shallow water-table environments in hilly terrains along with torrential rainfall make the slopes susceptible to instability. according to murck et al. (1996) during the prolonged monsoon phases, increased pore-water pressure creates favorable conditions for deep-seated landslides. in the present study area, groundwater is not uniformly distributed over all facets. therefore, groundwater investigation has been conducted facet wise. some facets have small flowing streams whereas others display wet to dry conditions. as fig. 3b depicts, surface terraces of groundwater of the study area portrays dry slopes (28 %), wet (22%), flowing (18 %), damp (18 %) and dripping (14 %), respectively. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 34 a b d c e f figure 3. maps showing slope facets and intrinsic landslide triggering parameters of the study area. (a)slope facet;(b) groundwater;(c)land use land cover;(d) relative relief;(e) slope morphometry; (f) slope material. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 35 landslidexternal triggeringhazarde parameters rain fall to assess and see the effect of rainfall to the landslide occurrences of the area, rain fall data for 35 years (1981-2013) was collected from national meteorology agency of ethiopia. it indicates that the maximum, minimum and mean annual rainfall in the study area is 3592.7 mm, 683.6 mm and 1,735.591 mm, respectively. the maximum annual rainfall was recorded in the year 1997, while the minimum in the year 2012. the monthly maximum rainfall is always in the months of july and august for all the recorded data. the study area is one of the areas receiving a high rainfall in the country having a bimodal rainfall nature which possesses alternating dry and rainy seasons. it receives exceptionally peak precipitation in the months of july and august. these two months alone contribute 43% of annual precipitation, which maximizes landslide occurrences. on the other hand months such as; march, april, may and september experience moderate amount of monthly precipitation. low amount of mean monthly precipitation is recorded in the months of october and november whereas december, january and february are generally regarded as dry months as they receive very low amount of monthly precipitation (fig. 4b) most of the landslides recorded in the study area happened when the annual rain fall exceeds the long term average rainfall. however, there were lower occurrences of major landslides between the years of 1983 to 1994 where the amounts of annual rainfalls were lower than the long term average except for 1986 and 1989. seismicity the earthquake shocks may be responsible for triggering new landslides and reactivating old landslides. the vibrations due to earthquake may induce instability, particularly in loose and unconsolidated material on steep slopes. the afar rift margin, where the study area is a b figure 4. mean annual and mean monthly rainfall of the study area (1981-2013). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 36 situated, is known for its earthquake occurrences. most of the earthquake ranges from small to medium level (atalay ayele, 2007). although not registered, the occurrences of landslide in association with afar earthquake in the area are common as evidenced by local dwellers. for example, as obtained from local information, there was a landslide occurrence around the nibamba gebriel and sina aregawi contemporaneous with the 1961 kara-kore earthquake. as portrayed above in figure 5, the present study area falls in seismic zone which has an intensity of 8, this zone has a ground acceleration of 0.10.5g. thus, the rating for ground acceleration of 0.1-0.5g, as per the standard ssep table is estimated to be 1.5. accordingly, this rating value has been figure 5. seismic risk map of ethiopia (source: laike mariam asfaw, 1986). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 37 distributed to all 60 slope facets in order to generate landslide hazard zonation map of the study area. earthquake induced landslide is so frequent in most parts of ethiopia that it needs intensive analysis of causative factors for any landslide including seismic factor. f a ce ts r el a ti v e r el ie f s lo p e m o rp h o m et ry s tr u ct u re s g ro u n d w a te r l u l c s lo p e m a te ri a l m a n -m a d e a ct iv it ie s s ei sm ic it y r a in f a ll 1 0.6 0.6 1.66 0.6 0.4 0.5 1 1.5 0.75 2 0.8 2 1.86 0 0.4 0.8 1.25 1.5 0.75 3 0.2 0.3 2.31 0 0.75 0.8 1 1.5 0.75 4 0.2 0.6 2.49 2 0.4 0.3 1 1.5 0.75 5 0.6 1 1.82 1 1.5 0.4 0.75 1.5 0.75 6 0.2 0.6 2.5 1 1.5 1 0.75 1.5 0.75 7 0.8 0.6 2.38 1.5 1.2 0.5 0.1 1.5 0.75 8 0.8 2 1.84 1.5 1.5 0.4 0.1 1.5 0.75 9 0.6 0.6 1.58 0 0.4 0.4 0.1 1.5 0.75 10 0.8 0.6 1.88 0 0.75 0.5 0.15 1.5 0.75 11 1 1 2.49 0 1.5 0.4 1.25 1.5 0.75 12 1 1 2.23 1.5 1.5 0.1 1 1.5 0.75 13 0.6 0.6 2 1.5 0.4 0.4 1 1.5 0.75 14 0.6 0.6 1.86 0 0.75 0.8 1 1.5 0.75 15 0.8 1.7 2.5 1.5 1.5 1 1 1.5 0.75 16 0.2 0.6 2.43 2 1.5 1 1.25 1.5 0.75 17 0.8 0.6 1.86 0 0.4 0.3 1 1.5 0.75 18 1 0.6 2.24 0.6 1.2 0.3 0.5 1.5 0.75 19 1 1.7 2.32 2 1.5 1 1 1.5 0.75 20 1 0.6 1.81 0 0.4 1 0.1 1.5 0.75 21 1 1.7 2.5 2 1.5 1 1.25 1.5 0.75 22 0.6 1 1.6 1 0.4 1 0.75 1.5 0.75 23 0.2 0.6 2.11 0.6 1.2 0.8 0.15 1.5 0.75 24 0.6 1 2.13 0 0.4 0.8 0.1 1.5 0.75 25 0.8 1 2.38 1 0.4 0.25 0.75 1.5 0.75 26 1 1 2.5 0 0.4 0.5 0.75 1.5 0.75 27 0.8 2 1.71 2 1.5 1 1 1.5 0.75 28 0.8 0.6 1.94 0 0.4 0.5 0.1 1.5 0.75 29 1 0.6 2.39 0.6 0.75 1 1 1.5 0.75 30 1 0.3 1.78 0 1.5 1 0.1 1.5 0.75 table 5.rating values assigned to each causative parameter in all slope facets east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 38 ….continuation of table 5 f a ce ts r el a ti v e r el ie f s lo p e m o rp h o m et ry s tr u ct u re s g ro u n d w a te r l u l c s lo p e m a te ri a l m a n -m a d e a ct iv it ie s s ei sm ic it y r a in f a ll 31 1 2 2.32 1 1.5 1 1.25 1.5 0.75 32 1 1 2.16 2 0.4 1 1.25 1.5 0.75 33 1 1 1.6 0.6 0.75 0.5 1 1.5 0.75 34 0.8 1 2.45 0.6 1.2 0.8 0.75 1.5 0.75 35 1 0.6 1.62 2 0.4 0.1 1.25 1.5 0.75 36 1 1.7 2.46 2 1.5 0.4 1 1.5 0.75 37 1 0.6 2.17 2 1.5 0.8 0.75 1.5 0.75 38 0.6 1 2.5 2 1.5 1 1.25 1.5 0.75 39 1 1.7 1.69 1 0.4 0.8 0.1 1.5 0.75 40 0.8 1 2.22 0 0.4 0.8 0.1 1.5 0.75 41 0.8 0.3 2.48 0.6 0.75 0.8 0.75 1.5 0.75 42 1 1 2.03 1 0.4 1 0.15 1.5 0.75 43 1 1 1.94 1 1.5 0.5 1 1.5 0.75 44 1 1.7 2.48 1.5 1.5 1 1.25 1.5 0.75 45 1 1 1.55 0.6 0.4 0.8 0.1 1.5 0.75 46 1 0.6 1.7 0 1.2 0.5 1 1.5 0.75 47 1 1 1.64 0 0.75 1 0.1 1.5 0.75 48 1 1 1.83 0.6 1.2 0.5 0.75 1.5 0.75 49 1 1.7 2 1 1.2 1 0.1 1.5 0.75 50 1 2 2.48 1.5 0.75 0.8 1.25 1.5 0.75 51 1 0.3 2.24 0 0.75 1 1 1.5 0.75 52 1 1 2.5 1 1.2 1 1 1.5 0.75 53 0.8 1.7 1.98 1 1.5 0.5 0.75 1.5 0.75 54 1 2 2.33 1 1.5 0.5 0.75 1.5 0.75 55 1 1 1.84 0.6 1.2 0.8 1 1.5 0.75 56 1 1.7 2.4 2 1.5 1 1 1.5 0.75 57 1 1 2.39 0.6 1.5 0.4 1.25 1.5 0.75 58 1 1 1.98 0 1.2 0.4 0.1 1.5 0.75 59 1 1 2.08 1.5 0.75 1 1 1.5 0.75 60 1 1.7 2.08 1 1.2 0.4 1 1.5 0.75 estimation of evaluated landslide hazard (elh) the evaluated landslide hazard indicates the net likelihood of instability and has been calculated facet-wise. the elh of an individual facet was obtained by adding the ratings of the individual causative factors obtained from the ssep rating scheme. evaluated landslide hazard is estimated as summation of ratings of intrinsic east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 39 and external parameters. on the basis of evaluated landslide hazard (elh), three categories of landslide hazard zones have been identified for the present study area (fig.6) viz., moderate hazard (mh), high hazard (hh) and very high hazard (vhh). these zones are distributed in accordance with the geology and geomorphology of the area. areal coverage of moderate hazard is 25 % whereas those of high hazard and very high hazard are 58 % and 17 %, respectively. these figures indicate that 75 % of the study area is very susceptible to landslide hazard moderate hazard zone moderate hazard zone represents relatively safe areas for construction and various infrastructural activities. it covers 25 % of the study area and out of 60 slope facets 15 fall in moderate hazard zone. moderate hazard zones are commonly distributed in northern, central and southern parts of the study area. chira meda area falls in this zone. even if this zone is not totally suitable, it should not be avoided because it has less probability of landslide occurrence as compared to others. high hazard zone the maximum area of the study area is covered by high hazard zone which accounts about 58 % of the study area. this zone represents high susceptibility to landslide hazard as compared to moderate hazard zone. some of the inventoried landslides are known to occur in this zone. high hazard zone is mostly dispersed in northern, eastern and southern parts of the study area. out of 60 slope facets, 35 are categorized under this zone. part of the town debre sina and armania also fall in high hazard zone. those slopes falling in this zone should be partially avoided or detailed study on larger scale (1:1000) should be done to evaluate the status of stability of these slopes. suitable control measures should also be identified before taking up constructions in order to minimize related geo-environmental hazards. very high hazard zone this zone represents totally unsuitable areas for constructions and settlement as well as agricultural activities. it covers the least area coverage and accounts 17 % of the study area. because of very high susceptibility of landslide occurrence in very high hazard zone, it is not advisable and should be totally avoided. about 10 facets of the study area have been identified to be very susceptible to landslide hazard. among these, very high hazard zones are located in north-western, central and southeastern part of the study area. part of town armania also falls in this zone. validation of ssep results the results obtained in present study correlated with the past landslide events recorded in the study area. thus, the final landslide hazard zonation map has been checked against the inventoried landslides of the study area for its validity. landslide inventory map of the study area has been prepared by integrating field observation and gps data collection with some ideas obtained by interviewing local people living around the study area. most of the inventory landslides are concentrated in high and very high hazard zones. out of 36 landslide inventories prepared during the field visit, 22 (61 %) of them fall in high hazard zone while east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 40 the remaining 14 (39 %) fall in very high hazard zone. the methodology followed during the present study relates intrinsic and external landslide triggering parameters to landslide occurrences. it has produced the results that match to past landslides. thus, slope stability evaluation parameter (ssep) rating scheme is found to be suitable methodology in landslide hazard zonation as it validated with the past landslide hazard events. conclusions the present study area has been affected by landslide hazard which devastated both public as well as private properties including infrastructures. it also threatened the life of people and animals living around the study area. landslide hazard and fatalities have been reported in the study area for a long period of time. several landslide hazard assessment approaches are available based on the kind of data input, study area size, data availability, kind of topography, etc., each of these approaches has its own benefits and shortcomings. concerning slope susceptibility in the present study area, areas covered with figure 6. a map showing evaluated landslide hazard of the study area. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 23-42 41 bare land, shrub and urban classes are more vulnerable to landslides, as compared to vegetation cover and forest classes which disfavor landslides. north, northeast and west facing slopes are favorable to landslides, whereas south, southwest and west orientation disfavor slope failure. moreover, slopes inclined at greater than 25° angle have strong susceptibility to landslides. distance to streams also has strong relations with landslide occurrence because areas close to streams prove to be highly prone to slope instability suggesting that slope undercutting by stream is an important process. most of the recent landslides observed during field visit and delineated through inventory mapping fall into high and very high hazard classes suggesting the reliability of the ssep rating scheme in delineating landslide prone areas of mountainous terrains. this approach is found to be more effective as it heavily depends on realistic field data andhelps to map landslides in large areas in a short period. acknowledgements the author is grateful to all who have contributed in one or other ways during office and fieldwork. specifically, i would like to express heart-felt thanks to tarun raghuvanshi (associate professor of engineering geology) for all academic inputs. i also appreciate addis ababa university, department of geology for providing all facilities including financial coverages needed to accomplish the present study without major obstacles. my appreciation is also extended to hawassa university, department of geology for creating favorable environment during publication process. references aleotti p. and chowdhury r. 1999. landslide hazard assessment: summary, review and new perspectives, bulletin of engineering geology & environment. 58:21-44. anbalagan r. 1992. landslide hazard evaluation and zonation mapping in mountainous terrain. engineering geology 32:269–277. asmelash abay and barbieri g. 2012. landslide susceptibility and causative factors evaluation of the landslide area of debre sina, in the southwestern afar escarpment, ethiopia. journal of earth science and engineering. 2:133-144 astis g.d., volpe l.l., peccerillo a. and civetta l. 1997. volcanological and petrological evolution of vulcano island (aeolian arc, southern tyrrhenian sea). journal of geophysical research 102 (b4): 8021-8050. atalay ayele 2007.the volcano-seismic crisis in afar, ethiopia, starting september 2005. earth & planetary sci. letters 255: 177–187 baeza c. and corominas j. 2001. assessment of shallow landslide susceptibility by means of multivariate statistical techniques. earth surface processes and landforms, 26(12): 1251-1263. barredo j.i., benavides a., hervas j. and van westen c.j. 2000. comparing heuristic landslide hazard assessment techniques using gis in the tirajana basin, gran canaria. island, spain. international journal of applied earth observation and geoinformation 2(1):. 9-23 casagli n., catani f., puglisi c., delmonaco g., ermini l. and margottini c. 2004. an inventory-based approach to landslide susceptibility assessment and its application to the virginio river basin, italy. environmental & engineering geoscience 10(3): 203–216. clerici a. 2002. a grass gis based shell script for landslide susceptibility zonation by the conditional analysis method. in: proceedings of the open source gis grass users conference 2002 trento, italy, 11-13 september 2002, pp 1-17 collison a., wade s., griffiths j. and dehn m. 2000. modelling the impact of predicted climate change on landslide frequency and magnitude in se england. eng. geol. 55: 205–218 dahal r.k., hasegawa s., masuda t. and yamanaka m. 2006. roadside slope failures in nepal during torrential rainfall and their mitigation. disaster mitigation of debris flows, slope failures and landslides, pp 503–14 gebreslassie mebrahatu 2011. landslide mapping assessment using gis techniques in dessie area, northern ethiopia. unpublished msc thesis, vrije universiteit, brussles, belgium, 111 pp. https://www.sciencedirect.com/science/journal/03032434 https://www.sciencedirect.com/science/journal/03032434 https://www.sciencedirect.com/science/journal/03032434 east afr. j. biophys. comput. sci. 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(2022), vol. 3, issue. 1, 1-8 *corresponding author: email: mereba480@gmail.com, +251 916 83 24 19 https://dx.doi.org/10.4314/eajbcs.v3i1.1s calves gastrointestinal nematodes and eimeria prevalence and associated risk factors in dairy farms, southern ethiopia maireg hailu1, kassahun asmare2, endrias zewdu gebremedhin3, vincenzo di marco lo presti4, maria vitale4, desie sheferaw2* 1molsd, sidama region, p.o.b 242, hawassa, ethiopia; 2hawassa university faculty of veterinary medicine, p.o.box 005, hawassa, ethiopia; 3ambo university college of agriculture and veterinary science, p.o.box 19, ambo, ethiopia; 4italian national reference centre for toxoplasmosis at istituto zooprofilattico sperimentaledella sicilia a. mirri, italy; keywords: calves; dairy farm; eimeria; nematode; ethiopia abstract dairy production plays a vital role in livestock farming in ethiopia. nevertheless, the productivity of the sector has been impacted negatively by the morbidity and mortality of replacement animals. a cross sectional study was therefore, aimed at estimating the prevalence of nematode and eimeria infection in calves in hawassa, shashemene and arsi negelle, southern ethiopia. to this end a flotation technique was used to recover nematode egg and eimeria oocyst from rectally collected faeces. the overall prevalence of gastrointestinal parasitic infection, nematode and eimeria species collectively, was 43.9% (95% ci=38.6-49.4). the estimated proportion of nematode, eimeria and mixed infection was 35.8%, 21.5% and 13.3%, respectively. among the potential factors considered faecal consistency, age and study area were found to increase recovery of nematode egg and eimeria oocyst in faeces (p< 0.05). area wise, the prevalence has been noted to be higher at arsi negelle followed by hawassa and shashemene (p< 0.05). besides, younger and diarrheic calves were found more infected by nematode and eimeria species than their adult and non-diarrhic counterpart. based on their morphological appearance, strongyle type (20.3%), trichuris (4.2%) and ascaris (16.3%) eggs, eimeria oocysts (21.5%) were observed. in the light of this finding the authors would like to advise the need for strategic intervention. introduction there is increasing demand for dairy products in urban and peri-urban areas, which indicates the importance of dairying in ethiopia (tegegn et al., 2013). ethiopia's cattle population is estimated at 60.4 million. calves accounted nearly for about 18% (csa, 2018). the sustainability of any dairy production depends on the successful program of raising calves for replacement (bath et al., 1985). in the modern societies, dairy farming has transformed into a business, where the owners have to look at improving the efficiency of the productions. one of the principal means of action to improve profit margins is to control and reduce costs. journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx east african journal of biophysical and computational sciences research article east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 1-8 2 this can be achieved by improving dairy animal health, especially the replacement calves. the costs of young stock diseases are difficult to quantify but are linked to a reduced growth and increased mortality rate. hence, the pre-weaning period represents a time of significant losses in the dairy industry (breen et al., 2012). health management of replacement animals is crucial for farm profitability. its productivity can be impacted negatively by the high mortality of replacement animals. the highest morbidity and mortality rates on dairy generally occur before weaning (breen et al., 2012; constable et al., 2017; radostits, 2001). in many dairy farms today, the young stocks are often observed less frequently than adult cows by both veterinary advisors and farm staff, resulting in delayed disease detection and treatment; veterinary attention becomes focused on diseased individuals as they arise rather than working towards producing groups of healthy calves (breen et al., 2012). gastrointestinal nematodes and eimeria species are the most important agents causing disease in calves (bruhn et al., 2012). calves are most vulnerable to gastrointestinal parasites in their first grazing season, although yearlings and, less often, adults are sometimes affected (constable et al., 2017). gastrointestinal parasitic infections, nematode and eimeria species, play a key role in the economic losses in that they cause low productivity, delayed growth, declined weight gain and death of the animal, and significant expenses of treatment (höglund et al., 2018; höglund et al., 2013; höglund et al., 2001; sutherland, and scott, 2010). even if various studies undergone on cattle helminthosis and eimeria infections, only limited information available. so this research output added to the existing information to build-up the data base. the aim of this study was to estimate the prevalence of nematode and eimeria species infections in calves and to identify potential risk factors associated with these infections. materials and methods study areas and animals the study areas were arsi-negelle, shashemene and hawassa which are located in southern part of ethiopia. the altitudes of the study areas range from 1,500 to 2,300 meters above sea level (masl). the annual rainfall varies, measuring 800–1,300 mm in hawassa, 500– 1,091 mm in arsi negelle, and 800–1,300 mm in shashemene. the mean annual minimum and maximum temperatures for hawassa, arsi-negelle and shashemene were 12.1ºc and 26.4ºc, 12.6 ºc and 27.3 ºc, and 14 ºc and 27 ºc, respectively (national meteorological agency, 2017). small scale dairy farming (i.e. urban and per-urban) was the characteristic feature of all the study areas. in the selected dairy farms, all calves (n=330) aged 12 months or younger were included in the study. the age of the calves was determined through interviews with the farm owners. study design and sample size a cross-sectional study design was employed to estimate the prevalence of git nematode and eimeria in calves of the dairy farms. the study was conducted from january 2018 to september 2018. lists of dairy farms were prepared in collaboration with arsi-negelle, shashemene and hawassa district animal health service 3 office. then, all farms having greater than or equal to three cows were purposively selected, making a total of 92 dairy farms with three or more calves. the sample size was computed by considering the gastrointestinal parasites prevalence, 61%, reported by telila et al. (2014) and taking in to account of 95% ci and 5% absolute desired precision(thrusfield, 2018). accordingly, the computed sample size was 365. but during the study period 330 calves were found in all the selected farms. hence, all the available calves were considered for the study. study methods data on farm size, management practices, and the presence of other animal species were gathered from farm owners using a pretested questionnaire. subsequently, approximately 15 gm of fresh fecal samples were collected directly from the rectum of selected calves using disposable arm-length gloves. the samples were placed in screw-cap universal bottles and labeled with unique codes matching the corresponding numbers on the data collection sheet. moreover, other information like farm name, calf age, sex, and faecal consistency (i.e. diarrhea, soft or normal) were recorded on the format prepared for this purpose. then the samples were placed in cool ice box and transported to the parasitology laboratory of the faculty of veterinary medicine, hawassa university. the samples were kept in the refrigerator and examined within 24 hours of the collection. the faecal samples were processed by the flotation technique, and a flotation fluid of saturated sodium chloride solution (specific gravity=1.2) was used; and the processed east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 1-8 samples were examined under 10x or 40x magnifications for nematodes eggs and eimeria oocysts (zajac and conboy, 2012; foreyt, 2001). data analysis al collected data were entered into a microsoft excel spreadsheet, where they were edited, coded, and summarized using descriptive statistics such as means and proportions. univariable logistic regression analysis was employed to evaluate the association of the putative risk factors considered in this particular study with calves infection by nematodes and eimeria species. those non-collinear variables (gamma=0.20) with a p-value of ≤ 0.25 in the univariable logistic regression analysis were subjected to a multivariable logistic regression analysis. finally, the model fitness was assessed by the hosmer–lemeshow goodness-of-fit test (dohoo et al., 2009). for the data analysis stata 14.2 software was used. the study considered a 95% level of confidence and 5% desired level of precision. results prevalence of gastrointestinal nematodes and eimeria the overall prevalence of gastrointestinal parasitic infection was 43.9% (95% ci=38.649.4) of which nematodes and eimeria species and mixed infections accounted for 118 (35.8%), 71 (21.5%) and 44 (13.3%), respectively. the prevalence of nematode and eimeria species infection varied between the study areas: shashemene, hawassa and arsi negelle (table 1). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 1-8 4 table1: animal level prevalence of nematodes and eimeria species infections of calves vs. variables considered for the study variables variables level no examined nematode species eimeria species no (%) positive 95% ci no (%) positive 95% ci study area shashemene 114 26 (22.8%) 16.0-31.2 14 (12.3%) 7.4-19.7 hawassa 179 74 (41.3%) 34.3-48.7 42 (23.5%) 17.8-30.2 arsi negelle 37 18 (48.6%) 33.0-64.6 15 (40.5%) 25.9-57.1 age 0-3 months 142 39 (27.5%) 20.7-35.4 24 (16.9%) 11.6-24.0 4-6 months 113 47 (41.6%) 32.8-50.9 32 (28.3%) 20.7-37.4 7-12 months 75 32 (42.7%) 31.9-54.2 15 (20.0%) 12.4-30.7 sex female 212 78 (36.8%) 30.5-43.5 48 (22.6%) 17.5-28.8 male 118 40 (33.9%) 25.9-43.0 23 (19.5%) 13.3-27.7 animal composition cattle only 269 109 (40.5%) 34.8-46.5 63 (23.4%) 18.7-28.9 mixed* 61 9 (14.8%) 7.8-26.2 8 (13.1%) 6.6-24.3 faecal consistency normal 148 44 (29.7%) 22.9-37.6 22 (14.9%) 10.0-21.6 semi-formed 150 56 (37.3%) 30.0-45.4 38 (25.3%) 19.0-33.0 diarrhea 32 18 (56.3%) 38.7-72.4 11 (34.4%) 19.9-52.4 total 330 118 (35.8%) 30.7-41.1 71 (21.5%) 17.4-26.3 * mixed= mixed with other domestic animals like equine, sheep and/or goats logistic regression analysis of potential risk factors for git nematode infection the univariable logistic regression analysis revealed that among the potential factors considered in the study areas, age and faecal consistency were associated with the occurrence of both nematode species (table 2) and eimeria species in calves (table 3). all the risk factors, variables, were non-collinear (γ is between 0.254 and 0.195), and hence, those risk factors with p<0.25 in univariable logistic regression were subjected to the multivariable analysis. the odds of acquiring nematode infection by calves in arsi negelle and hawassa were 3.8 and 2.8 times higher as compared to shashemene, respectively (table 2). similarly, the likelihood of shedding eimeria oocysts by calves of arsi negelle (adjusted or=6.2, p< 0.001) and hawassa (adjusted or=2.6, p=0.007) was significantly different from that of calves in shashemene (table 3). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 1-8 5 table2: logistic regression analysis of potential risk factors for git nematode infection in calves, southern ethiopia. variables variables level no. examined no. (%) positive univariable multivariable or 95% ci p-value or 95% ci p-value study area shashemene 114 26 (22.8%) rf. rf. hawassa 179 74 (41.3%) 2.4 1.4-4.0 0.001 2.8 1.6-5.0 ≤ 0.001 arsi negelle 37 18 (48.6%) 3.2 1.5-7.0 0.003 3.8 1.7-8.7 0.002 age 0-3 months 142 39 (27.5%) rf. rf. 4-6 months 113 47 (41.6%) 1.9 1.1-3.2 0. 018 2.2 1.2-3.8 0.007 7-12 months 75 32 (42.7%) 2.0 1.1-3.6 0.024 2.2 1.1-4.0 0.017 sex female 212 78 (36.8%) rf. male 118 40 (33.9%) 1.1 0.7-1.8 0.599 faecal consistency normal 148 44 (29.7%) rf. rf. semi-formed 150 56 (37.3%) 1.4 0.9-2.3 0.165 1.6 1.0-2.6 0.076 diarrhea 32 18 (56.3%) 3.0 1.4-6.6 0.005 5.7 2.4-13.7 ≤ 0.001 total 330 118 (35.8%) or = odds ratio, rf. = reference table3: logistic regression analysis of potential risk factors for eimeria species infection in calves, southern ethiopia. variable category no. examined no. (%) positive univariable multivariable or 95% ci p-value or 95% ci p-value study area shashemene 114 14 (12.3%) rf. rf. hawassa 179 42 (23.5%) 2.2 1.1-4.2 0.019 2.6 1.3-5.3 0.007 arsi negelle 37 15 (40.5%) 4.9 2.1-11.5 0.000 6.2 2.5-15.7 ≤ 0.001 age 0-3 months 142 24 (16.9%) rf. rf. 4-6 months 113 32 (28.3%) 1.9 1.1-3.6 0. 030 2.3 1.2-4.4 0.010 7-12 months 75 15 (20.0%) 1.2 0.6-2.5 0.572 2.3 0.6-2.7 0.527 sex female 212 48 (22.6%) 1.2 male 118 23 (19.5%) rf. 0.7-2.1 0.505 faecal consistency normal 148 22 (14.9%) rf. rf. semi-formed 150 38 (25.3%) 2.0 1.1-3.5 0.026 2.1 1.2-3.9 0.016 diarrhea 32 11 (34.4%) 3.0 1.3-7.1 0.012 5.3 2.0-13.6 0.001 total 330 71 (21.5%) based on their morphological characteristics of their eggs (i.e. when examined under 10x east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 1-8 6 and/or 40x microscopic magnification) four major groups of gastrointestinal nematode parasites were identified (table 4). table4: types of parasites identified based on morphology of their eggs/oocyst group of parasites proportion (%) std. err 95% ci strongyles 20.3% 0.02 16.3-25.0 trichuris 4.2% 0.01 2.5-7.1 ascaris 16.3% 0.02 12.7-20.8 eimeria 21.5% 0.02 17.4-26.3 among the different reproductive disorders, abortion and retained fetal membrane showed statistically significant association (p<0.05) with uterine infection that was expressed either in the form of endometritis or metritis (table 4). table-4. association of uterine infection with the other reproductive disorders of cows as a predisposing factor predisposing factors number of cows cows with uterine infection cows without uterine infection 2 pvalue rfm 11 7(63.6%) 4(36.4%) 11.9 0.001 abortion 6 5(83.3%) 1(16.7%) 13.11 0.000 dystocia 3 1(33.3%) 2(66.7%) 0.16 0.688 hypocalcemia 3 1(33.3%) 2(66.7%) 0.16 0.688 rfm=retained fetal membrane discussion calves are vital members of the dairy farms and represent the future replacement stock, and they deserve special attention and great care of health (chang’a et al., 2010). the overall prevalence of gastrointestinal parasitic infection was 43.9 %, of which nematode and eimeria species infections were accounted for 35.8% and 21.5%, respectively. the prevalence of nematode species observed during this study was in a general agreement with the report from the west hararghe zone (tulu and lelisa, 2016; kemal and terefe, 2013). the multivariable logistic regression analysis showed that among the potential risk factors considered in the study areas age and the study areas were found significantly associated with infection of calves both by nematode and eimeria species (table 2 and 3). the variation between the study areas might be due to the differences in the prevailing management factors in the areas (constable et al., 2017). the prevalence of nematode species infection increases as the age of the calves increases. similarly, tulu and lelisa (2016) reported that as the age of calves increased, the exposure time to the infective stage of larvae and oocysts also increased. relatively the lower eimeria infection during the first three months of age was due to the effect of colostral east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 1-8 7 authors contributions: all authors agreed with the content and to submit for publication. contributions of each author is as follows: ma data collection; ka design of work, data analysis and comment on draft; ezg design of work, data analysis and comment on draft; vdmlp design and comment on draft; ds design of work, data analysis and draft preparation. references bangoura b. and bardsley k. 2020. ruminant coccidiosis. vet. clin. food anim. 36: 187-203. bath d.l., dickinson f.n., tucker h.a. and appleman, r.d. 1985. dairy cattle: principle, practices, problems, profits. 3rd edition, lea and febiger, washington square, philadelphia. pp. 473 breen j., down p., kerby m. and bradley a. 2012. restoring the dairy herd: rearing young stock and replacing cows: in dairy herd health edited by martin-green, cab international, nosworthy way wallingford oxford shire ox10 8de, uk. pp. 3572 bruhn e.r.p., júnior f.a.s., de oliveira carvalho a.h., orlando d.r., da rocha c.m.b.m. and guimarães, a.m. 2012. occurrences of eimeria spp. and gastrointestinal nematodes in dairy calves in southern minas gerais, brazil. rev. bras. parasitol. vet. jaboticabal 21(2): 171-175. chang’a j.s., mdegela r.h., ruth ryoba r., løken t. and reksen o. 2010. calf health and management in smallholder dairy farms in tanzania. trop anim. health prod. 42: 1669-1676. constable d.p., hinchcliff w.k., done h.s. and grünberg w. 2017. veterinary medicine: a textbook of the diseases of cattle, horses, sheep, pigs, and goats, 11th edition, elsevier ltd. 3251 river port lane, st. louis, missouri. pp. 401-408, 603-617 csa 2018. report on livestock and livestock characteristics, agricultural sample survey 2017/18 (2010 e.c.), statistical bulletin 587, volume ii, addis ababa. pp. 94 dohoo i., martin w. and stryhn h. 2009. veterinary epidemiologic research, 2nd ed. avc, charlottetown, prince edward island. pp. 239–249. fiege n., klatte d., kollmann d., zahner h. and bürger h.j. 1992. eimeria bovis in cattle: colostral transfer of antibodies and immune response to experimental infections. parasitol. res. 78(1): 32-38. antibodies from infected cows (fiege et al., 1992). again the prevalence of eimeria species infection declined after 7 months of age probably as a result of immunity development to re-infection by the same species of eimeria (senger et al., 1959). cross protection between species does not occur, and hence, undoubtedly the calves might be infected by other species of eimeria (bangoura and bardsley, 2020). the proportion of both nematode (or=5.7, p< 0.05) and eimeria species (or=5.3, p< 0.05) infection was significantly higher in diarrheic calves than calves with normal faeces consistency. in dairy farms diarrhea was most frequently observed disorder in various parts (tamrat et al., 2020; żychlińska-buczek et al., 2015; megersa et al., 2009; wudu et al., 2008). it is known that some nematodes species and eimeria species known to damage the intestinal epithelial cells leading to inflammation and cause diarrhea (constable et al., 1017; ramadan et al., 2015). in conclusion, gastrointestinal parasitic infections are highly prevalent in the study areas. this study identified that study area, age of the calves and faecal consistency were significantly associated with the prevalence of nematode and eimeria species infection of calves. therefore, it is advisable to introduce strategic interventions that include regular treatment of the herd including the calves. conflict of interest: there is no financial or other relationship that might lead to a conflict of interest. consent to participate: informed consent was obtained from all participants involved in the study. east afr. j. biophys. comput. sci. 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wudu t., kelay b., mekonnen h.m. and tesfu k. 2008. calf morbidity and mortality in smallholder dairy farms in ada’aliben district of oromia, ethiopia. trop. anim. health prod. 40: 369-376. zajac a.m. and conboy g.a. 2012. veterinary clinical parasitology, 8th edition, john wiley and sons ltd., the atrium, southern gate, chichester, west sussex, po19 8sq, uk. pp. 352 żychlińska-buczek j., bauer e., kania-gierdziewicz j. and anna wrońska a. 2015. the main causes of calf mortality in dairy farms in poland. j. agric. sci. technol. a. 5(5): 363-369. slide number 1 editorial board members table of contents slide number 6 volume 2.pdf cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 6 volume 2.pdf cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 east east afr. j. biophys. comput. sci. (2022), vol. 3, issue. 2, 11-24 *corresponding author: email: jovineemma2007@yahoo.co.uk, +255 769910443 https://dx.doi.org/10.4314/eajbcs.v3i2.1s effect of pressure on carbon monoxide oxidation on titania supported platinum nanoparticles catalyst jovine emmanuel university of dar es salaam, mkwawa university college of education, department of chemistry,, p.o.box 2513 iringa-tanzania keywords: activity; co conversion; particles; platinum and titania abstract thermographic testing methodology was developed to facilitate measurements of particle dimension and substrate influence in heterogeneous catalysts. a screening chip with several areas of less stress silicon nitride membranes which displays less heat conductivity and heat capacity was used. heat produced during the reaction on catalysts deposited on membranes was established through ir camera which gave the value of the turn over frequency. effect of pressure on co conversion on titania supported pt particles of different dimension was measured on 120 catalysts concurrently. the reaction was studied at various o2 and co pressures at 170 ℃ and 240 ℃. at these temperature conditions, activity increased with increase of o2 and co pressure, in agreement with previous reports. introduction there is a fair idea on catalysis starting from ancient times. it largely contributes in a number of applications as in chemical, agricultural, food and pharmaceutical industries, manufacturing and energy transformation and environmental safety (scheidtmann et al., 2001, emmanuel, 2022). estimates indicate that above 90% of chemical production routes depend on a single or multiple catalytic pathways (armor, 2011, emmanuel and hayden, 2022). metal catalysts largely rely on substrate, shape and dimension of supported metal nanoparticles catalyst. reports indicate that the reactivity of properly characterised supported catalysts are important in knowing the influence of particle dimension and substrate. a good case of such a catalyst revealing a greater substrate and particle dimension influence on reactivity is supported platinum (pt) in low temperature conversion of tiny molecules like carbon monoxide (co) and hydrocarbons (liu et al., 2010). platinum (pt) is among the frequently used metal catalysts in enormous applications over the decades. dobereiner reported the activity of pt in 1800s where it was applied in the catalysis of h2 and east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article mailto:jovineemma2007@yahoo.co.uk https://dx.doi.org/10.4314/eajbcs.v3i2.1s east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 12 o2 in portable lamp (somorjai, 1994). besides, pt related catalysts are applied in different reactions such as the transformation of aliphatic straight-chain organic molecules to aromatic molecules and branched molecules, in huge scale hydrogenation in chemical and petroleumrefining industries and ammonia conversion (somorjai, 1994). more significantly, it is used for co oxidation and unburned hydrocarbons in car emissions control (franceschetti et al., 2003). platinum catalyst, on the other hand, is the most commonly applied and active electrode in fuel cell technology (franceschetti et al., 2003). although pt is widely used in various fields, it is an expensive precious metal and less abundant which make its application in various technologies largely challenging (cameron et al., 2003). because pt bare high cost, the priority has been its application at the atomic scale in heterogeneous catalysis. this includes the spreading of pt particles on high surface area metal oxide substrates like al2o3, tio2 and fe2o3 which reduce the quantity of pt integrated in the catalyst (somorjai, 1994). supporting pt lowers the catalyst expenses in addition to increasing effective surface area of the catalyst in addition, it strengthens catalyst’ particles. substrates like tio2 are directly involved in reaction pathways through reactants and intermediates activation thus, improving the activity. pt catalysts on carbon is widely applied in pemfcs technology (emmanuel, 2022). however, application of pt catalyst is affected because of the decline of catalytic efficiency due to particle disintegration, rusting of cathode substrate and co inhibition (kim and jhi, 2011). the decline of efficiency is because of greater interaction of pt and co which inhibits o2 from getting on the surface of a catalyst (schubert et al., 2001; molina et al., 2009; liu et al., 2010). carbon monoxide conversion reaction on pt supported catalysts is widely investigated (santra and goodman, 2002; liu et al., 2010; slavinskaya et al., 2011; allian et al., 2012; dobrin, 2012). it is known that because of strong interaction with oxygen and pt surface, o2 adsorbs and break down to generate effective surface adsorbed atomic oxygen which combines with adsorbed co to generate co2 (bamwenda et al., 1997; haruta, 2003; gao et al., 2009). carbon monoxide conversion on pt proceeds very efficiently with a conversion rate dependent on co and oxygen partial pressures. previous reports show that the reaction needs chemisorbed oxygen and co on pt surface, a pathway termed as langmuir-hinshelwood mechanism (mccash, 2001; kolasinski:, 2002; mcclure and goodman, 2009; liu et al., 2010, santos et al., 2010). studies indicate that this reaction is influenced by reactants pressure, coverage and surface temperature (kolasinski:, 2002). however, competitive adsorption among co and o2 is reported. although co can adsorb on an o2 occupied surface, o2 cannot adsorb on co occupied surface. with high co occupied surface, the reaction is restricted by o2 thus, raising co pressure inhibits the reaction because no extra adsorption sites for o2. however, at low co occupancy, o2 adsorption proceeds rapidly and the reaction relies on surface coverage of co and o2 (kolasinski:, 2002). given the catalytic efficiency of pt catalyst, the reactivity is hampered by co inhibition in gas-phase co oxidation thus, maximum co oxidation to co2 is attained at minimal co surface occupancy (mcclure and goodman, 2009). in this regards, pt catalysts on substrates are perceived as poor catalysts for small temperature co conversion (li et al., 2008). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 13 studies indicate that fe2o3 supported pt nanoparticles catalyst exhibits unusual high catalytic properties for co conversion at small temperature (liu et al., 2010). the activity is associated with the capability of fe2o3 to provide active oxygen during the reaction. titania supported pt nanoparticles less than 5 nm show low activity for co oxidation reaction (rashkeev et al., 2007). theoretical studies propose that pt nanoparticles between 1 and 2 nm dimensions are more effective for co oxidation (dobrin, 2012). further reports indicate that pt particles of 2 nm dimension are the best effective for co conversion in comparison with those of 3 nm and 5 nm dimensions (kageyama et al., 2013). electrocatalysis benefits from combinatorial synthesis and thorough characterization of oxide-supported metal nanoparticle catalysts, readily enabling high-throughput screening of various reactions using electrochemical chips. however, applying analogous methods to heterogeneous catalysis is considerably more complex. a breakthrough solution, published by emmanuel et al. (2019), utilizes a 100-channel microreactor array and mass spectroscopy to study the h2-d2 exchange reaction on thin-film, small-area alloy catalysts. for less complex reactions in which it is not important to establish selectivity, net activity established in the heat generating reaction through infrared thermography methodology is promising. this methodology was applied for testing of catalysts in the conversion of hydrogen and octane on high area catalyst samples (emmanuel et al., 2019). however, expansion of the methodology to arrays of properly characterised catalysts like metal supported electro-catalysts to achieve structure/activity influences is a challenge (hayden, 2013). the considerably low surface area of planar catalysts needs an amplified sensitivity so as to identify the heat produced in the course of a reaction. the current study reports the impact of pressure on reactivity of titania supported pt particles catalyst for co conversion by applying a nano-fabricated screening chip which enables simultaneous testing of a chains of supported pt catalysts of controlled particle dimension at different co and o2 pressures. materials and methods creation of platinum nanoparticles catalysts a combinatorial technique centred on a high throughput physical vapour deposition (htpvd) developed by brian et al. (hayden et al., 2009) was used to create thin films of tio2 and tio2 supported pt nanoparticles catalyst, figure 1. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 14 figure 1: schematic diagram of ht-pvd system indicating two cryo-pumped thin film synthesis chambers a and b, sputtering and surface analysis chambers and the load lock (adapted from hannah, 2012). this technique creates thin films through condensation of evaporated material onto a substrate. the deposition chamber consisted of three electron gun (e-gun) evaporation sources (temescal) and three knudsen cell (k-cell) sources (dca). the ht-pvd system operational base pressure was 1 x 10-10 mbar. in the present study, electron beam sources, e-gun 1 was applied to evaporate ti, pt was evaporated from e-gun 3. titania layers of about 200 nm were deposited onto a catalyst screening chip from titanium (99.995 %, alfa aesar metals) from e-gun 1 and oxygen (air products, special gases, 99.999 %) at a constant pressure of 9.7 x 10-6 torr at 1 sccm oxygen flow rate and plasma source, prf = 300 w at a deposition rate of 4 å/s with substrate retained at ambient temperature throughout film creation. the widths of titania layer deposits were managed through depsition time and sample thickness was subsequently achieved via calibration of deposition rates from afm readings. the afm (vecco autoprobe m5) instrument was applied in a contact mode with a silicon cantilever, resonance frequency of 180 khz, spring constant of 5nm-1 with an estimate tip (csc17 probe, mikromasch) curvature of 10 nm. characterization of platinum nanoparticles characterization and distribution of particle dimension was conducted by using tem where a small layer of tio2, l5-25 nm thick, was created onto small carbn cated copper tem grids (agar scientific). the grids bared tio2 produced under the same deposition conditions as a catalyst screening chip. platinum particles east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 15 from pt source (e-gun 3), were created onto a screening chip where tio2 support material was previously created through ht-pvd technique. the deposition rate of 4 å/s were achieved by creating several thick layers from short to extended times, showing that the thickness as established on contact masked samples using afm was relative to the depsition duration. the rate of pt deposition (0.15 å/s) was established through creation of continuous pt small films, and reduced deposition durations (30 s – 360 s) applied to create pt particles via nucleation and growth on titania substrates at 250 ℃. for surface characterization of pt nanoparticles on titania substrate, pt nanoparticles were grown onto formvar® carbon coated copper grids (agar scientific) coated with a small layer of titania 15-25 nm thick for transmission electron microscope (tem) measurements. characterization of particles was conducted by tem prior deposition onto the screening chip for assurance of particles creation. using jeol 3010 instrument, tem images were attained at an accelerating voltage of 300 kv containing a gatan ccd camera for capturing images. x-ray photoectron spectroscope (xps) studies were conducted in ultra high vacuum (uhv) system containing a twin anode x-ray source (mg kα and al kα) and a vg clam single channel xps system analyser. depositions the substances were undertaken onto silicon nitride on silicon and on a 10 x 10 or 12 x 12 array nanofabricated catalyst screening chip (450 µm silicon wafer thickness) on which a low pressure chemical vapour created (lp-cvd) silicon nitride membrane (300 nm and 600 nm) has been previously created. the screening chip was back etched to create individual membranes. the ht-pvd system was set up on a “wedge” deposition to generate different particle dimensions distributions throughout the support. a silicon chip with the dimension of 35 mm x 35 mm was fabricated (450 mm thick silicon wafer) for ir thermography readings and an array of 10 x 10 silicon nitride membranes (1.5 mm x 1.5 mm) of 600 nm thickness were produced by back etching of silicon to a layer of lp-cvd silicon nitride as described earlier (emmanuel, 2022). the membrane with 200 nm of titania substrate was optically transparent. for temperature measurement of the membrane, a small graphitic carbn layer (ca. 200 nm) was created on the back of the membrane supplying an emissivity approximate to that of a black body. thin sin membrane offered a supprt for the catalyst with small thermal mass and less thermal cnductivity to the surrounding silicn chip thus, heat produced in the course of a reaction on the catalyst could subsequently increase membrane temperature. testing of platinum nanoparticles for catalytic activity a screening chip with a catalyst created on the whole chip was placed on a heated sample holder with a heat shield to enable the whole chip to be heated evenly up to 250 oc. the sample holder was placed in a uhv system an ir transparent window (caf2) and the surface of the chip was captured (50 mm focal length camera lens) by a thermal camera (jade iii, cedip) operating in the spectral range of 3.6 – 5.1 µm with a thermal sensitivity of 20 mk. spatial resolution was 320 x 240 pixels and the whole 12 x 12 array was imaged to fill the detector. reactions were conducted in a turbomolecular pumped uhv system with a east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 16 base pressure of 1 x 10-10 mbar and the temperature response of the catalyst on the membrane for a given power input (from an exothermic reaction) was established via finite element thermal modelling (comsol multiphisics®) (emmanuel, 2022). it is hypothesized that energy loss from the membrane primarily occurs via thermal conduction through the membrane itself, including the titania support and graphite layer, to the underlying silicon chip. radiative and convective losses were estimated to be zero therefore, extra radiative and convective wastes over a few degrees temperature over the base temperature of reaction were expected to be very minimal (emmanuel, 2022). for co conversion reaction (∆h = -283 kjmol-1) (emmanuel, 2022) and a pressure of 1 x 10-3 mbar, assuming each molecule is converted, the theoretical power was 2.289 x 10-4 js-1 mm-2 (emmanuel, 2022). this resulted in a calculated temperature increase of 4 °c (δt = 4 °c) at the center of the membrane. the chip's calculated sensitivity enabled the determination of the reaction turnover frequency (tof) at the catalyst surface. however, the uncertainty in the thermal conductivity values of the membrane's composite layer led to an estimated error of approximately ±30% in the absolute tof values. a detailed simulation of the temperature distribution across the 1.5 mm x 1.5 mm membrane was previously reported (emmanuel, 2022). results and discussion images of tem for pt catalyst supported on titania resemble those reported earlier in terms of their shape and growth mode (emmanuel, 2022), figure 2. the tem images facilitated the determination of particle dimension reliance of supported pt in relative to the equivalent coverage of pt created. on the figure, particles of pt appear in black relative to the white substrate background. at a shorter deposition period (30 seconds) in (a), particles are smaller (black). conversely, when deposition periods escalate, particles increase in dimension because extra pt is being added as witnessed in the dimension of particles in (b), (c) and (d), respectively, with deposition periods of 30 seconds, 2, 3.5 and 5 minutes, respectively. in order to establish the change of particle dimension distribution after co conversion because it was not possible to have it established directly on the chip by tem, xps measurements were conducted prior and after the reaction. a small change to higher binding energy was observed which was associated with final-state effect, consistent with earlier studies (liu et al., 2014). the raise in the intensity was detected with increasing particle dimension, showing that pt particles were growing in size as extra pt was deposited. the study of pt core level energies show a small but recognizable shift in binding energy. studies indicate that the binding energy shifts governed by the species to which an atom is attached and the binding energies shifts for core level electrons can emerge from initial-state or final-state effects (attard and barnes, 1998, kolasinski:, 2002). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 17 figure 2: images of tem for pt particles at different deposition periods, (a) 30 seconds, (b) 2 minutes, (c) 3.5 minutes and (d) 5 minutes with a mean particle dimension of (a) 1.6 nm, (b) 2.6 nm, (c) 4.9 nm and (d) 6.7 nm initial-state effects (chemical shift) are attributed to chemical bonding which largely affects electronic configuration of an atom leading into a large shift in binding energy of up to 10 ev (emmanuel, 2022). thus, atoms in a high oxidation state generate xps peaks at high binding energy as compared to similar atom in a low oxidation state (emmanuel, 2022). however, the final-state effects are because of the ejection of an electron from an atom which a b c d east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 18 corresponds to an ionic state producing a hole in place of the removed photoelectron (emmanuel, 2022). effect of the binding energy shift due to final-state is often a slight binding energy shift compared to that of initial-state effect. because the core level binding energy shift for pt particles detected in the current study is smaller, typically less than 1 ev, it can be linked with final state-effect, consistent with the earlier reports (zhang et al., 1997; guerin et al., 2006; liu et al., 2014,). figure 3 show the reliance of pt 4f7/2 binding energy for pt particle dimension recorded on the screening chip prior and after the reaction on pt supported catalysts. figure 3: binding energy of pt particle size for the pt 4f7/2 prior and after the catalytic reaction. at a base temperature of 170 oc on pt catalyst, a pressure of a gaseous mixture was 7.2 x l0-2, 8.4 x 10-2 and 1.04 x 10-1 mbar with o2: co ratio of 1:1. for a pre-exposed o2 catalyst surface, the pressure was 1.5 x l0-1, 1.9 x l0-1 and 2.2 x 10-1 mbar with o2: co ratio of 2:1, 1:1 and 1:1, respectively, while on a pre-exposed co catalyst surface the pressure was 1.5 x 10-1, 1.7 x 10-1 and 2.2 x 10-1 mbar with o2: co ratio of 1:2, 1:1 and 1:1, respectively. besides at 240 ℃ and o2: co ratio of 1:1, the pressure was 6 x 101, 1.1 and 2.4 mbar. the temperature was determined concurrently n the catalysts integrating ver a 5 minutes interval. catalysts were created such that particles dimension was constant throughout the rows and differed in the columns of the screening chip. the variation in temperature east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 19 across a row of similar particle dimensions was 0.2 ℃, far less than that in the columns and was attributed to a partial shielding of the gas flux at the boundaries of the sample by the holder. the increase, ∆t, in average was applied to establish the oxidation rate of co to co2 at the catalyst assuming the enthalpy of reaction was ∆h = 283 kj mol-1 (emmanuel, 2022). the mass of pt and number of pt atoms at the surface of the particles per catalyst area of catalyst was computed from tem images, assuming the particles were hemispherical (hayden et al., 2009, emmanuel, 2022). this allowed the computation of tof at pt surface. figure 4 presents the tof for co conversion reaction at 170 ℃ with the pressure of 7.2 x l0-2, 8.4 x l0-2 and 1.04 x l0-1 mbar and o2: co ratio of 1:1. figure 4: tof for co conversion on pt particles at a pressure of 7.2 x 10-2 (blue triangles), 8.4 x 10-2 (red circles) and 1.04 x 10-1 mbar (black squires) with o2: co ratio of 1:1 at 170 ℃. in figure 5 is the tof for co conversion reaction on a pre-exposed o2 catalyst surface with a pressure of 1.5 x 10-1, 1.9 x 10-1 and 2.2 x 10-1 mbar at o2: co ratio of 2:1, 1:1 and 1:1, respectively, at 170 ℃. figure 6 presents the tof for co conversion at 170 ℃ on a preexposed co catalyst surface with a pressure of 1.5 x 10-1, 1.7 x 10-1 and 2.2 x 10-1 mbar at o2: co ratio of 1:2, 1:1 and 1:1, respectively east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 20 figure 5: tof for co conversion reaction on pt particles catalyst for a pre-exposed o2 pt surface, pressure of 1.5 x 10-1 (blue triangles), 1.9 x 10-1 (red circles) and 2.2 x 10-1 mbar (black squires) at o2: co ratio of 2:1, 1:1 and 1:1, respectively, at 170 ℃. figure 6: tof for co conversion on pt particles catalyst for a pre-exposed co pt surface, pressure of 1.5 x 10-1 (blue triangles), 1.7 x 10-1 (red circles) and 2.2 x 10-1 mbar (black squires) at o2: co ratio of 1:2, 1:1 and 1:1, respectively, at 170 ℃. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 21 the tof for co conversion reaction at 240 ℃ with a pressure of 6 x 10-1, 1.1 and 2.4 mbar at o2: co ratio of 1:1 is also presented, figure 7. figure 7: tof for co conversion on pt particles catalyst at 240 ℃ and o2: co ratio of 1:1, pressure of 6.1 x 10-1 (blue triangles), 1.1 (red circles) and 2.4 mbar (black squires). at each temperature, there is an increase in tof as reactants pressures increase revealing that pt catalyst is more active for co conversion at higher pressure. for a pre-exposed o2 catalyst surface at 170 ℃, a similar trend in tof of pt catalyst was observed by increasing pressure, figure 5. the same behaviour in tof was noticed for a pre-exposed co pt catalyst surface at 170 ℃, figure 6. again, reactants pressure led to a significant increase in activity of pt catalyst for co conversion with increasing pressure at 240 ℃ as shown by the values of tof in figure 7. thus, the highest tofs of pt particles catalyst were achieved with increasing reactants pressure at higher temperature. therefore, at each temperature, there is a linear relationship between the tofs and pressure for co conversion on pt catalyst. the activity trend achieved in the current study is consistent with earlier findings which addressed the dependence on o2 and co pressure of the reaction rate for co conversion on pt catalysts (li et al., 2013, berlowitz et al., 1998). for a pre-adsorbed o2 surface, tof increased by raising co pressure at o2: co ratio of 1:1, pressure of 2.2 x 10-1 mbar and on a pt surface pre-adsorbed with co, a similar trend was achieved, consistent with earlier reports (berlowitz et al., 1998; johanek et al., 2004; li et al., 2013). tof of pt catalyst at 240 ℃ and higher reactant pressures resulted in the highest tofs although a slight decline in activity was observed at 2.4 mbar, figure 7. for example, tof declined from 4.355 s-1 at 1.1 mbar to 4.174 s-1 at 2.4 mbar on pt particle dimension of 1.3 nm. the fall of activity is attributed to co inhibition of pt catalyst surface east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 22 prohibiting o2 adsorption and breakage on the catalyst surface, an important reaction pathway thus, decreasing pt activity, in agreement with previous findings (mcclure and goodman, 2009). results show that co conversion on pt catalyst is influenced by reactants pressure and surface temperature (kolasinski:, 2002). for instance, at 170 ℃ and o2: co ratio of 1:1, figure 4, tof raised from 0.259 s-1 at 7.2 x 10-2 mbar to 1.991 s-1 at 1.04 x 10-1 mbar on pt particle dimension of 1.3 nm. a similar raise in activity with increasing reactants pressure was attained on a pre-adsorbed o2 pt catalyst surface where tof increased from 0.671 s-1 at 1.5 x 101 mbar to 1.889 s-1 at 2.2 x 10-1 mbar on pt particle dimension of 1.3 nm, figure 5. besides, tof increased from 0.946 s-1 at 1.5 x 10-1 mbar to 1.903 s-1 at 2.2 x 10-1 mbar on pt particle dimension of 1.3 nm for a pre-adsorbed co pt surface, figure 6. however, a competitive adsorption exists among co and o2 towards pt surface, though co can adsorb on an o2 occupied surface, o2 cannot adsorb on a co occupied surface. therefore, at high co occupied surface, the reaction is restricted by o2 thus, raising co pressure prevents the reaction because there are no extra adsorption sites for o2. contrary, at low co occupied surface, oxygen adsorption occurs rapidly and the reaction relies on the surface coverage of co and o2 (kolasinski:, 2002). usually, higher co conversion to co2 is attained at situations that allow least co surface occupancy (mcclure and goodman, 2009). in addition to temperature and pressure, co conversion on pt is dependent on particles dimension where the smallest particles exhibit higher activity. although there is no common agreement from literature about the influence of particle dimension for supported pt catalyst, results show that pt particles within 1.1 nm and 10 nm, for co conversion at different temperatures the activity increases with decreasing particle dimensions (li et al., 2013). this is because for particle dimension of lower than 10 nm, the comparative number of kink sites, steps and corners raises monotonically with declining dimension and the lowcoordinated surface atoms bare huge difference in the capability to react with molecules from the gas phase thus, accelerating the reaction (overbury et al., 2006; li et al., 2013). however, it is necessary to relate the activity trend with pressure at 170 ℃ and that attained at 240 ℃. results show higher activity of pt catalyst at 240 ℃ as reflected in tof with increasing pressure, for instance, tof increased from 3.312 s-1 at 6.1 x 10-1 mbar to 4.355 s-1 at 1.1 mbar on pt particle dimension of 1.3 nm. studies show that pt surface is exceptionally active at high reactant gas pressure and temperature because at low temperatures, the co repressed regime takes over and the reaction is prohibited by adsorbed co which preventing adsorption and breakage of o2 thus, leading to low catalytic activity of pt catalyst (gao et al., 2009, mcclure and goodman, 2009, liu et al., 2010). however, at all pressure and temperature conditions investigated in the current study, co conversion rate increased with increasing pressure. such activity trend illustrates the influence of pressure and temperature for co conversion on pt nanoparticles catalyst in addition to pt particles dimension. this behaviour is consistent with earlier findings on the reliance of pressure of o2 and co of the reaction rate for co conversion on a similar system (berlowitz et al., 1998; li et al., 2013). these result can be considered in the light of the influence of pressure to explain high activity of pt catalyst at high pressure and temperature east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 11-24 23 among other factors (li et al., 2013). the findings indicate that at a particular temperature, an increase of pressure yields the highest activity compared to that obtained at low pressure and temperature. thus, these results provide the evidence of the influence of pressure on co conversion on pt particles catalyst at a given reaction temperature. conclusion the co conversion on titania supported pt catalyst of different particle dimension between 1.3 nm and 7.8 nm at different reactants pressures was measured simultaneously on 120 catalysts at 170 and 240 ℃ and at different reactants pressures. the xps studies indicated a small change of particle dimension after the reaction. at each temperature studied, a linear relationship between tof for co conversion on pt catalyst and pressure was attained. however, the highest tof for co conversion on pt was observed at higher pressure and temperature of 240 ℃, consistent with earlier findings on similar catalyst system (li et al., 2013, berlowitz et al., 1998). however, a slight decline in activity was observed with a pressure of 2.4 mbar at 240 ℃ which is attributed to co poisoning of pt catalyst, consistence with earlier findings (mcclure and goodman, 2009). besides, the smallest pt particles attained the higher tofs, in agreement with earlier reports. acknowledgement the author honorably appreciates the significant contribution, advise, guidance, encouragement and supervision roles from professor brian hayden. the author also acknowledges the financial support from the employer, mkwawa university college of education. references allian a.d., kakanabe k., fujdala k.l., hao x.h., truex t.j., cai j., buda c., neurock m. and iglesia e. 2011. chemisorption of co and mechanism of co oxidation on supported platinum nanoclusters. j. am. chem. soc.. 133(12): 4498-4517 armor j.n. 2011. a history of industrial catalysis. catalysis today. 163: 3-9. attard g. and barnes c. 1998. surfaces, new york, oxford university press inc. bamwenda g.r., tsubota s., nakamura t. and haruta m. 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(2022), vol. 3, issue. 1, 58-68 east *corresponding author: email: beshow.betela@gmail.com, +251 972691341 https://dx.doi.org/10.4314/eajbcs.v3i1.6s analysing covid-19 verified, recuperate and death cases in ethiopia using arima models birhanu betela warssamo department of statistics, college of natural and computational sciences, hawassa university, hawassa, ethiopia, p. o. box: 05 keywords: covid-19 cases; days; autoregressive integrated moving average abstract applying a successful prediction of the confirmed, recovered and deaths is supposed to be the basic requirement to successfully control the dissemination rate of diseases. time series models have widely been considered as the suitable methods to forecast the confirmed, recovered and deaths because of the virus. the objective of this research is to apply the autoregressive integrated moving average (arima) modelling approach for projecting covid-19 confirmed, recovered and deaths cases in ethiopia. over strict tracks of all phase of box-jenkins strategy, arima (1,1,1), arima (16,1,2) and arima (0,1,1) models for confirmed case, recovered and death case, respectively were selected as the most appropriate models for predicting corona virus cases of ethiopia. using these models, a predictions of five month a heads future situation of covid-19 confirmed case, recovered and death case (jan 3, 2021 to may 3, 2021) has made. the results showed that in the coming five months from jan 3, 2020 to may 3, 2021, the number of covid-19 confirmed, recuperated and deaths cases in ethiopia may reach up to 320,597; 168,912 and 4438, respectively. by and large, the size of the corona virus distribution was increased from time to time in the past ten month, until 3rd jan, 2021, and it is anticipated to continue faster than before for the coming 5-months, until the end of may, 2021, in ethiopia and more rapidly than before while the peak will remain unknown yet. therefore, an effective execution of the precautionary measures and a rigorous compliance by circumventing carelessness with the rules such as prohibiting public congregations, travel restrictions, social distancing, and strict use of personal protection measures may improve the dissemination rates of the virus. further, through updating more new data with constant reconsideration of predictive model provide useful and more accurate prediction introduction the primary event of corona virus (covid-19) eruption was informed on december 31, 2019 in wuhan and then, it has been put across the universal deadly disease owning harsh new type of hazard to individual vigour and life in a continues way. according to world health organization (2020), more than 135,045 covid-19 cases, 2,083 deaths, and 121,594 recoveries have been reported in ethiopia and 101,483,628 cocid-19 cases, 2,185,413 deaths and 73,386,329 recoveries and 25,908,918 active cases among these 25,801,597(99.6%) in east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article file:///d:/eajbcs/birhanu%20betela/bes https://dx.doi.org/10.4314/eajbcs.v3i1.6s east afr. j.biophys.comput. sci. (2022), vol. 3, no. 1, 58-68 59 mild condition and 110,289(0.4%) series or critical cases and 73,386,329 (97%) are recovered and 2,185,413(3%) are dead across the globe during the study period (who, 2020). the quantity of covid-19 cases rapidly goes up in mid-january, and the infection quickly blowout beyond china’s boundaries. as of this research, it has extended to 219 countries all over the globe (who, 2019). despite broadening covid-19 influences, there are key public health questions. how many individuals will be diseased? how does the condition vary day by day? how many individuals will die? these inquiries could be re-joined by predicting the possible futures of this contagion via time series models. however, broadly used time series models and tools do not essentially have high forecasting precision, particularly for medical researches (huppert and katriel, 2013). by fitting models and creating precision forecasting unfailingly may improve community health judgment-making (yonar et al., 2020). on march 13, 2020, the federal ministry of health has confirmed a corona virus disease (covid-19) index case in addis ababa, ethiopia. the case, which was publicized on the 13th of march 2020, is the first one (index case) to be reported in ethiopia since the beginning of the outbreak in china in december 2019. the case is a 48year old japanese man reported to have travelled from japan to burkina faso and then reached in ethiopia. the person developed symptoms and presented at the health center in addis ababa from where the rapid response team (rrt) moved him to the isolation facility in yeka kotebe. he was clinically stable, with no serious symptoms. subsequently, on 16 march 2020, the administration of ethiopia have been announcing to appliance numerous defensive actions such as emerging community alertness about over all behavior of the infection and its stoppage tools like cleansing of ways and marketplaces, isolation of mistrusted and diseased cases, lockdown of the universities, schools, house of worship, and announcing state of crisis. ethiopian administration has applied protective measures directly after the infection has been stated the world disease. yet, the spread has continued quick for the reason that supreme of the individuals have been carelessness in certain of defensive actions such as public distancing and mass assembly. on the other, populace movement through the border from the next-door nations like sudan, djibouti, kenya and somalia has a lion part for the current movement of quick spread of infection in ethiopia. accordingly, covid-19 spread would get thoughtful in ethiopia, and its coming movement is also likely to depend directly or indirectly on the spread of covid-19 within and outside of all those neighboring african countries. investigating the trends and predicting the coming indices of the infection in ethiopia must be accompanied in order to put in a place operative monitoring policies. though the spread mechanisms of the infection is not totally recognized, the number of new cases are harshly growing, and the effects of inhibition should be assessed on numerical data where numerical investigation is extra significant. actually, several states in the world up to now have functional data-driven statistical models alike autoregressive integrated moving average (arima) for forecasting of future movements of the communicable infection. subsequently, to model the exponential growing rate of the virus, yichi et al. (2020) and gupta and pal (2020) conducted their study using a east afr. j.biophys.comput. sci. (2022), vol. 3, no. 1, 58-68 60 linear based time series model, auto regressive moving average (arima family) model. time series forecasting models like arima is the ordinary method which gives clothed forecasts on time series data in fast time (hyndman et al, 2008). this method of investigation has been extensively functional, for its consistency and rapid application by numerous stakeholders. hence the objective of this work is to put on the autoregressive integrated moving average (arima) modelling approach for predicting corona virus (covid-19) confirmed cases, recovered and deaths in ethiopia to empower the community health organizations to conduct trust worthy day-to-day prediction and to arise with appropriate intervention policies, deliver direct and long-term route of the illness and play role to the body of knowledge in epidemiologic study method. materials and methods study area the research was carried out in ethiopia, where the virus quickly spread and disturbing. according to the un population estimates, whole population of the country is 114,963,836 peoples. research data the everyday time series data of covid-19 of ethiopia from 13 march 2020 to january 3, 2021 were gathered from the official website of johns hopkins university (2020): https://goto.now/awy0o. spss version 20 statistical software was functional to achieve statistical data investigation on the confirmed, recovered and deaths case of covid-19 datasets. technique of data study time series analysis aims to tell consistent and expressive statistics and use this information to forecast upcoming values of the series. time series models try to predict the upcoming values by investigating the former and present. it contemplates past data and tries to arise some procedure which will clarify those existences and forecast upcoming values. the distinct feature of time series analysis is consecutive observations are typically dependent and that the investigation must take methods to classify the designs which characteristically happen in the data. based on this detail, amongst time series methods, this research applied arima model in order to evaluate the upcoming movement situation of covid-19 in ethiopia. auto regressive integrated moving average (arima) modelling it is the other most regularly used time series models as it considers varying movements, periodic fluctuations and random disturbances in the time series. it also appropriate for all types of data, containing non-stationary data, which is if there is no systematic change in mean (no trend), no systematic change in variance and periodic variations has removed (box and jenkins, 1976). in practice, most of the time series are non-stationary and wei, 2006 commends eliminating any non-stationary sources of variation in time series data. in most case, common method for attaining stationary is to put on consistent differencing and log transformation to the original time series (xt). if differencing a time series d times results in a stationary series, then that original series is said to follow an autoregressive integrated moving https://goto.now/awy0o east afr. j.biophys.comput. sci. (2022), vol. 3, no. 1, 58-68 61 average (arima) process, denoted as arima (p, d, q) and can be written as:     tt d wx   where: autoregressive operator can be expressed as:   p p  ...1 2 2 moving average operator    p ...1 1 differencing operator    dd  1 it is the expression of dth consecutive differencing so as to make series stationary. wt is a gaussian white noise series with mean zero and variance  2 w . testing for stationary: before emerging a box-jenkins modelling process, it is significant to verify whether the data under study encounters basic suppositions such as series stationary. a time series is well-thought-out as stationary if its statistical properties such as mean and variance are constant over time (box and jenkins, 1976). many testing procedures for stationary are planned in the literature. in this research, correlogram test were functional for testing whether the series is stationary. the correlogram test: it is one way to characterize a series with respect to its reliance over time. it usually recognized as sample autocorrelation function (acf), which is plot of sample acf coefficient against observation difference in time (lag). as indicated in (box and jenkins, 1976) if the sample acf decays very slowly in non-seasonal and seasonal lag snit indicates that differencing is wanted and an insinuation for series non-stationary. constructing arima model: as planned by (granger and newbold, 1986) method, in order to construct arima model for a specific time series data, must follow four phases: model identification, estimation of model parameters, diagnostic checking for the identified model, application of the model (forecasting). model identification: with this phase, the amount of differencing compulsory attaining stationary and the order of both the seasonal and non-seasonal ar and ma operators are determined. the autocorrelations function (acf) and the partial autocorrelation functions (pacf) are the two most valuable tools in any attempt at time series model identification (shumway and stoffer, 2010). to determine the number of differencing (d), non-seasonal autoregressive (p) and moving average (q) parameters, the guideline specified in (lehmann and rode, 2001) are used. therefore, if pacf cuts off after lags q and acf tail off, then arima (0, d, q) model is identified. if acf cut off after lag p and pacf tail off, arima (p, d, 0) model is acquired. finally, if both acf and pacf tail off, then the recognized model will be arima (p, d, q). parameter estimation: after selecting the most suitable arima model, the parameters are estimated by maximum likelihood estimation. diagnostic checking: it deals with the residual assumptions in order to decide whether the residuals from fitted model are independent, constant variance (lehmann and rode, 2001). east afr. j.biophys.comput. sci. (2022), vol. 3, no. 1, 58-68 62 visual analysis: it is a method for investigating plot of the residual over time. if visual reviews of the plot tell that they are haphazardly distributed over time, then it is a residual independence (lehmann and rode, 2001). residual autocorrelation function (racf): with this test, to say that residual follows a white noise process, roughly 95% of the autocorrelation coefficient should fall within the range of ±1.96/squ(n) (grasselli et al, 2020). if the nominated model is insufficient, the three-step model building process with other model is typically repeated many times until a satisfactory model obtained. the final model selected can then be used for forecast determinations (box and jenkins, 1976). figure 1 distribution of confirmed cases of covid19 in ethiopia(mar 3, 2020jan 3, 2021) predicting: it is last phase in time series modelling, the aim is to forecast future values of a time series, 𝑋𝑡 + 𝑚, 𝑚 = 1,2,… based on the data collected to the present, 𝑋 = {𝑋𝑡 , 𝑋𝑡 − 1, … , 𝑋𝑙}. qmtqmtdpmtdpmtmt wwxxx    ...... 1111 results descriptive analysis results the first confirmed case of the covid-19 in ethiopia (the index case) is described on 13 march 2020 with one infected foreigner. then after, the administration of ethiopia has without delay in use different measures to put off and manage the infection, but the case has been expontially increasing and widely distributing until sep 1, 2020. from aug 01, 2020 to oct 01, 2020 large number of people are infected by the virus and the number of infection shows slight decline until the study period jan 3, 2021 (fig.1). similarly, the first recovered cases reported on jun 01, 2020 and the recovery cases increased parallel with the confirmed cases. there was a large number recovery cases during december 1, 2020 to january 1, 2021 (fig 2). figure2: distribution of covid-19 recovered case in ethiopia (13 mar, 2020-jan 3, 2021) as shown in fig 3, the first mortality/death case was reported on april 2, 2020. the number of deaths was increasing with the increase of the number of confirmed cases. high number of deaths in ethiopia was reported during aug 03, 2020 – oct 1, 2020. as shown on fig 4, the east afr. j.biophys.comput. sci. (2022), vol. 3, no. 1, 58-68 63 confirmed numbers of cases are increasing and the recovery case is also more increasing parallel to the confirmed cases. figure 3: distribution of death cases in ethiopia (mar 3, 2020-jan3, 2021) the number of death cases is also increasing but interestingly the recovery cases (green line) is very closed to confirmed cases (blue line) but the death (yellow line) is going away from the confirmed cases (blue line), that is, the death cases are not increasing in the same level as confirmed cases and the death line is getting flat. figure 4: covid-19 confirmed, recovered and death cases in ethiopia (mar 3, 2020-jan3, 2021). results from arima modelling of covid19 case result in testing stationary: the first step in every time series investigation containing arima modelling is to see whether the time series is stationary. in this research, time series plot and autocorrelation function (acf) were practical to check the stationary. the pattern of the series of covid-19 confirmed cases, recovery and death cases shows increasing trend indicating the mean and the variance of the series are not constant throughout time and this shows the process is not stationary and the data need to be differencing and with the one step differencing, d=1, we got stationary data. result in model identification for confirmed cases: from table 1 arima (1,1,1) and arima (5,1,1) are recommended since they have lest bayesian information criterion (bic) and highest adjusted r-square, but by b-j methodology, parsimonious models give better transforms: natural log confirmed case_mean recoverd_mean deathcase_sum east afr. j.biophys.comput. sci. (2022), vol. 3, no. 1, 58-68 64 forecast than over-parameterized models. therefore, arima (1,1,1) is selected. table 1: tentative models confirmed cases arima(1,1,1) arima(1,1,2) arima(5,1,1) arima(5,1,2) adj r square 88.9 88.9 89.3 89.3 bic 9.855 9.877 9.911 9.933 result in model identification for recovered case: from table2 arima (15,1,1) and arima(1,1,2) are selected but by b-j methodology , arima (1,1,2) is the best model to forecast the confirmed cases. but residual acf and pacf are not flat, that is lags 16 and 15 are very significant indicating there is white noise in the series and we should re estimate the model by adding ar(16) in the model. thus the appropriate model to forecast recovery case is arima (16, 1, 2). table 2: tentative models recovered cases arima(1,1,1) arima(1,1,2) arima(15,1,1) arima(15,1,2) adjusted r square 60.4 60.6 66.1 66.4 bic 11.614 11.631 11.775 11.788 result in model identification for death case: from auto and partial auto correlation plot a candidate ma(q) models were recommended. that is arima (0,1,1) models is recommended. result in model diagnosis: according to (box and jenkins, 1976), all the models that accepted and satisfied all residual tests and the parameters meaningfully vary from zero must be included and nominated as candidate model for forecast. residuals acf and partial acf plot for confirmed, recovered and death cases, all the lags are inside the 95% confidence interval showing there is no problem of white nose so the models are ready for use of prediction. east afr. j.biophys.comput. sci. (2022), vol. 3, no. 1, 58-68 65 table 3: arima models & coefficients for best selected model. covid-19 cases model bic r-squared mape coefficient p value confirmed case arima(1,1,1) 9.855 .889 0.309 1   =-0.233 0.016 417.0   0.00 recovered case arima(16,1,2) 11.732 0.69 0.439 1   =0.257 0.00 2   =0.230 0.00 3   =0.129 0.034 6   =0.185 0.003 15   =-0.330 0.00 998.0   0.00 deaths cases arima(0,1,1) 2.649 0.679 0.407 801.0   0.00 predicting precision assessment if the fitted models achieve well in predicting, the estimate error will be comparatively minor and the mean absolute percentage error (mape) should be close to 5%. from table 3, it can be witnessed that the accuracy of forecasts measured by the mean absolute percentage error (mape) cast out to be 3.09% for arima (1, 1, 1) model, 4.39% for arima (16, 1, 2) and 4.07% for arima (0, 1, 1) model, which are relatively less than 5%. this implies that those models would perform better in predicting the confirmed, recovery and death cases of covid-19 well. figure 5: forecasted value with 95% prediction interval for confirmed cases in ethiopia figure 6: forecasted value with 95% prediction interval for recovered cases in ethiopia east afr. j.biophys.comput. sci. (2022), vol. 3, no. 1, 58-68 66 fig 5, fig 6 and fig 7 presents prediction of covid-19 confirmed, recovered and death cases and it gives the direction and tendency of the epidemic and forecasts the likely development of future epidemics. the figs shows, a forecasts of five month a heads future situation of covid-19 confirmed case, recovered and death case (jan 3, 2021 to may 3, 2021). infected cases, recovered and death cases are expected to considerably increase in the coming five months. by the end of may 3, 2021, cumulative confirmed, recovered and death cases across ethiopia, will reach 320,597, 168,912 and 4438 respectively. figure 7: forecasting value with 95% prediction interval for deaths case in ethiopia discussion it is crucial to generate consistent and appropriate forecasting model that can assistance health system administrations and other stakeholders to prevent the extra blowout of covid-19. time series forecasting models is the statistical method which provides a clothed forecast and has been extensively practical for trend of communicable sickness in rapid time (fanelli and piazza 2020). arima models are predictive technique that offers a good forecast and has been widely used for the rapid trend of infectious diseases (holt, 1957, hyndman et al, 2008, shumway and stoffer, 2010). over strict follows of all phase of box-jenkins strategy, arima (1,1,1), arima (16,1,2) and arima (0,1,1) models for confirmed case, recovered and death case respectively were selected as the best models for predicting covid-19 cases of ethiopia. time series analysis of covid-19 provides the direction and movement of the epidemic and forecasts the probable progress of upcoming epidemics. using these models, a forecasts of five month a heads future situation of covid-19 confirmed case, recovered and death case (jan 3, 2021 to may 3, 2021) has made. in diverse area, a lot of numeric researches have been showed to forecast new case of covid-19 case using arima model (gupta and pal, 2020; li et al., east afr. j.biophys.comput. sci. (2022), vol. 3, no. 1, 58-68 67 2020, yonar et al., 2020; zhan et al., 2020) which are consistent with this research. in line with the current study, li et al. (2020) and das (2020) also used arima model to predicting covid-19 epidemic in india and china, respectively and showed that the infected case were increasing. covid-19 cases reported in the country is assumed to exceed 160,585 in the five months of 2021. at the end of may, inline projected cumulative infections across ethiopia to hit 156,610 on average (hyndman et al, 2008), while the real value until 19 may was just 189,137 cases and 1352 deaths (yonar et al., 2020). this means that the number of people who are corona-virus-positive in ethiopia can increase more than predicted (hyndman et al, 2008). however, in this analysis, the cumulative confirmed, cumulative recovered and cumulative death forecast cases on may 3, 2021, are 320,597, 168,912 and 4438, respectively. similar to the predicted values in this study, variation of pandemics in ethiopia in the first five months has been shown to increase (hyndman et al, 2008). the scholars disprove the effect of geographical difference and temperature in reducing the distribution of covid-19 (granger and newbold, 1986). the covid-19 pandemic has caused significant global social and economic disruption. while pre-protective strategies are crucial in managing the spread of covid-19, this study does not evaluate their impact due to the unavailability of exposure data conclusions since the study shows the increase in the number of deaths and confirmed cases in ethiopia, more attention should be given to the control and prevention of covid-19. without the implementation of effective infection control measures by the government of ethiopia, the covid-19 situation is expected to deteriorate, leading to greater consequences for the nation. consequently, this study advocates for the development and enforcement of sustainable pandemic control strategies. utilizing the arima model allows for forecasting the future spread of covid-19 based on existing data, which will assist institutions in formulating appropriate policies. references box g. and jenkins g. 1976. time series analysis: forecasting and control. holden day. canters for disease control and prevention. corona virus disease 2019 (covid-2019). 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[https://www.who.int/emergencies/ diseases/novel-coronavirus-2019/situation-reports] accessed: 2020-05-05. world health organization (who) 2020. corona virus disease (covid-19) pandemic, who https://worldometer.info/coronavirus.assesedon.jan 28, 2021. 09:09 worldometer, “coronavirus cases,” worldo meter, pp. 1– 22, 2020, doi: 1101/2020.01.23.20018549v2. assessed on jan 28, 2021. 09:09 gmt yichi l., bowen w., ruiyang p., chen z., yonglong z., zhuoxun l, xia j. and, bin z. 2020. mathematical modelling and epidemic prediction of covid-19 and its significance to epidemic prevention and control measures. annals of infectious disease and epidemiology 5 (1): 1052. yonar h., yonar a, tekindal m.a and, tekindal m. 2020. modelling and forecasting for thenumber of cases of the covid-19 pandemic with the curve estimation models, the box-jenkins and exponential smoothing methods. eurasian j. med. oncol. 4(2):160–165. zhan c., chi k., lai z., hao t., and, su j. 2020. prediction of covid-19 spreading profiles in south korea, italy and iran by data-driven coding. medrxiv.. https://doi.org/10.1016/j.ijforecast.%202003.09.015 https://bit.ly/3ot9ytc https://doi.org/10.1016/j.jinf.2020.02.014 https://bit.ly/35bxkty https://worldometer.info/coronavirus.%20assesed%20on.jan east east afr. j. biophys. comput. sci. (2022), vol. 3, issue. 2, 40-47 *corresponding author: email: mereba480@gmail.com, +251 916 83 24 19 https://dx.doi.org/10.4314/eajbcs.v3i2.1s ovine eimeria infection, opg and determinants in and around gondar town, ethiopia senait belay1 and desie sheferaw*1 1hawassa university faculty of veterinary medicine, p.o.box 005, hawassa, ethiopia; keywords: eimeria; gondar; opg; prevalence; sheep; ethiopia abstract the study aimed to assess the prevalence of ovine eimeria infection, assess the putative risk factors, and the intensity of infection. a cross-sectional study design was employed and the study was carried out from november 2017 to may 2018. a total of 422 sheep were selected by systematic random sampling technique, and from these animals, faecal samples were collected and examined for eimeria oocysts. of the selected and examined sheep 132 (31.3%, 95% ci=26.8-35.7) were found infected by eimeria species. eimeria infection prevalence was significant (p <0.05) higher in lambs/young than the adult, in females than males, and in poor body condition than in medium body condition sheep. moreover, the prevalence of eimeria infection was significantly (p <0.05) higher in sheep with soft faeces than in normal faeces sheep and semi-intensive than extensive sheep production. the intensity of eimeria species infection was influenced by the age, sex, body condition, fecal consistency, and production system of sheep (p< 0.05). the overall mean oocysts per gram of faeces was 2390.6 (95% ci=2007.5-2773.8). the mean opg was significantly higher in lambs, with poor body conditions and female sheep. in addition, it was higher in sheep with soft faeces and an extensive production system. in conclusion eimeria species infection was an important problem of sheep production in the study area. generally, this study's results provided useful information to design and implement appropriate control strategies. finally, it is recommended that further study identify the species of eimeria circulating in the areas. introduction ethiopia is home to a large and diverse livestock resource (gizaw et al., 2010); and the country has around 17 million sheep (csa, 2021). this means sheep represent an important segment of the livestock system in the country. sheep are important sources of income for the agricultural communities, represent one of the country’s major sources of foreign currency through the export of skins and meat, and are a source of animal protein. they also play a major role in the food supply and social well-being of rural communities living in conditions of extreme poverty, which is the particular case in parts of ethiopia (dagnew et al., 2017; gizachew et al., 2014). the major constraints for sheep production in ethiopia are feed shortage, grazing land limitation, problems related to veterinary services, and diseases (welday et al., 2019; kenfo et al., 2018; nigussie et al., 2013). according to gizaaw et al. (2013), one of the research gaps is sheep diseases, of which east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article mailto:mereba480@gmail.com https://dx.doi.org/10.4314/eajbcs.v3i2.1s east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 40-47 41 parasites are among the most important diseases. among parasitic diseases, coccidiosis is an important protozoan parasitic infection that is responsible for low productivity, impaired growth, and mortality in sheep populations (ayana et al., 2009). it is caused by a protozoan parasite of the genus eimeria that affects young animals in particular (hendson and agnes, 2002). they are highly species-specific, meaning the species of eimeria that infect sheep will not infect goats or cattle and vice versa (constable et al., 2017; aitken, 2007). coccidiosis in sheep was reported in various parts of the world (khan et al., 2011; bukar, 2007; toulah, 2007). also reported from ethiopia (lakew and seyoum, 2016; ayana et al., 2009), but in the country, there are some areas with limited information about the prevalence of eimeria species infection in the sheep. there is no study of eimeria species infection prevalence of sheep in and around gondar. therefore, the aims of this particular study were to estimate the prevalence of eimeria species infection, to identify the putative risk factors and to assess the intensity of infection in sheep in and around gondar. materials and methods study area this study was carried out in and around gondar town (azezo, tseda, maksegnit, angereb, ayra and fenter kebeles) from november 2017 to may 2018. gondar town is located in amhara regional state, north-west ethiopia. the study area is located at an latitude and longitude of 12.30 13.80 °n, 35.30 35.7°e; and its altitude is on average about 2220 meters above sea level. the mean annual rainfall and temperature of the area were 1172mm and 19.7oc, respectively (national meteorological agency, 2017). study animals the study animals of the study were sheep flock reared under an extensive and semi-intensive management system. all grazing age groups, local breed,, and both sexes of sheep were considered for the study (breed information was obtained with personal communication with the owners). study design across sectional study design was employed to estimate the prevalence of eimeria infection of sheep in and around gondar town. during this study faecal consistency, age, sex and body condition of the sheep, the hygienic status of the animal house and management system were considered as potential risk factors (independent variables) for eimeria infection (dependent variable) of sheep. the study animals were divided into three age groups, namely: lamb (less than 6 months old), young (6-12 months old), and adult (over 12 months old) as described by esgpip (2009) and gatenby et al. (1991). faecal consistency was examined and classified as normal (formed pellets), soft (pellets not formed) as described by (platzer et al., 2005). body conditions of the study animals were scored as poor, medium, and good as described by russel (1991). sample size determination & sampling techniques the required sample size for this study was computed by considering 50% prevalence of ovine eimeria spp. infection, to obtain the east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 40-47 42 maximum sample size. the formula described by thrusfield (2018) was used to compute the sample size required for the study. the study considered a 95% confidence interval and 5% absolute precision. therefore, 384 sheep were required for the study; but 422 animals were selected and studied. a systematic random sampling method was used to select the study animals from the target sheep flock. study methodology faecal sample collection faecal samples, about 10gm, were collected directly from the rectum of the sheep by using arm-length plastic gloves, and placed in screw capped universal sample bottle. each samples was labeled with the necessary information about the animal and the sample (i.e. age, sex, faecal consistency and body condition score) were recorded on the format prepared for this study. moreover, the hygienic status of the animal and the management system was carefully observed. finally, the samples were packed in icebox with ice packs and transported to the parasitological laboratory of the faculty of veterinary medicine, gondar university. the samples were kept in refrigerator at 4ºc until examined. collected samples were examined within 24 hours for the presence or absence of eimeria oocysts as described previously (taylor et al. 2016; zajac and conboy, 2011). qualitative and quantitative faecal examination from the collected faecal samples, 3gm was weighed and properly mixed with 42ml flotation fluid (saturated salt solution). then sieved by tea strainer and filled to test tube, and then centrifuged at 1,500 rpm for 3 minutes. the sample taken out of the centrifuge and the supernatant was examined for eimeria oocysts under 10x and 40x microscopic magnifications as described by urquhart et al. (1996). those faecal samples positive in the qualitative examination were subjected to quantitative examination. for this examination, mcmaster egg counting technique (urquhart et al., 1996; maff, 1986) was used to determine the number of oocysts per gram of faeces and assess the intensity of infection. data management and analysis collected data were entered into a microsoft excel spreadsheet, cleaned, coded, and then summarized by descriptive statistics like percentages or proportion and mean. the prevalence of eimeria infection was computed by dividing the number of positive animals by the total number of animals examined and multiplied by 100. the association of the various risk factors considered for this study was analyzed by univariable logistic regression analysis. those non-collinear factors with a pvalue of ≤ 0.25 in the univariable logistic regression analysis were further analyzed by multivariable logistic regression analysis. the dependability of the fitted model was further evaluated using the receiver operating characteristic curve (roc). finally, the model fitness was assessed by the hosmer-lemeshow goodness fit test as described by dohoo et al. (2009). the mean number of oocysts per gram of faeces was computed by considering those sheep positive in the qualitative examination for oocysts. oocysts per gram of faeces was determined and then after, to normalize the data were log-transformed (log10+1). the transformed data were analyzed by using a t-test for the existence of associations between oocysts per east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 40-47 43 gram of faeces (opg) and the risk factors were analyzed by paired t-test. for the data analysis, stata 14.2 software (stata corp 4905 lakeway drive, college station, texas 77845 usa) was used. results qualitative faecal examination results from a total of 422 examined sheep 132 (31.3%, 95% ci=26.8-35.7) were infected by eimeria species. the association of risk factors for infection of sheep by eimeria species was shown in table 1. table1: results of lgistic regression analysis of risk factrs for eimeria infection in sheep in and around gondar variable category no. examined prevalence univariable multivariable no. (%) positive 95% ci or p-value or 95% ci p-value age lamb 96 56 (58.3) 48.4-68.3 6.3 ≤0.001 5.4 3.2-11.9 ≤0.001 young 151 44 (29.1) 21.8-36.4 1.8 0. 022 2.8 1.3-4.2 0.005 adult 175 32 (18.3) 12.5-24.0 rf. rf sex male 237 96 (19.5) 13.7-25.2 rf. rf female 185 36 (40.5) 34.2-46.8 2.8 ≤0.001 3.8 1.7-4.9 ≤0.001 faecal consistency normal 242 56 (23.1) 17.8-28.4 rf. rf. soft 180 76 (42.2) 35.0-49.5 2.4 ≤0.001 5.7 2.6-7.1 ≤0.001 bcs poor 147 73 (49.7) 41.5-57.8 3.6 ≤0.001 2.2 1.1-3.0 0.030 medium 275 59 (21.5) 16.6-23.3 rf. rf managemen t system extensive 244 43 (17.6) 12.8-22.4 rf. rf semi-intensive 178 89 (50.0) 42.6-57.4 4.7 ≤0.001 5.7 2.6-7.1 ≤0.001 total 422 132 (31.3) 26.8-35.7 bcs= body condition; nb. or= odds ratio; ci= confidence interval; rf=reference category all the independent variables were noncollinear [gamma value (γ) value fall between 0.6 and +0.6], and the univariable analysis pvalue was <0.25. hence, all the risk factors were subjected to multivariable analysis. the final model had hosmer-lemeshow χ2 (8) = 13.66, p= 0.091, and roc= 0.7621 that there is no significant difference between the observed and predicted values. quantitative faecal examination result the minimum and maximum numbers of oocysts per gram of faeces (opg) were 300 and 12,500, respectively. the overall mean opg of faeces was 2390.6 oocysts/gram of faeces (table 2). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 40-47 44 table2: mean opg and t-test analysis of risk factors for intensity of eimeria species infection risk factors and its levels no examined no positive mean opg 95% ci t-value p-value sex *female 237 96 2618.9 2146.4-3091.3 4.95 ≤0.001 *male 185 36 1781.9 1172.0-2391.9 rf. age -lamb 96 56 3294.8 2638.3-3951.3 8.01 ≤0.001 -young 151 44 1920.5 1324.7-2516.2 2.44 0.015 -adult 175 32 1454.7 914.8-1994.6 rf. body condition *poor 147 73 3266.6 2714.7-3818.4 7.12 ≤0.001 *medium 275 59 1306.8 931.1-1682.5 rf. faecal consistency -soft 180 76 3008.7 2462.5-3554.9 4.84 ≤0.001 -normal 242 56 1551.8 1107.0-1996,6 rf. management system *extensive 244 43 2061.6 1421.5-2701.8 rf *semi-intensive 178 89 2549.6 2067.9-3031.2 7.62 ≤0.001 overall 422 132 2390.6 2007.5-2773.8 discussion and conclusions the prevalence of eimeria species infection of sheep in and around gondar was 31.3%. all risk factors considered during this study for eimeria species infection of sheep were significantly (p< 0.05) influencing infection of sheep by eimeria species. lamb and young sheep were 5.4 and 2.8 times more likely to be exposed to eimeria species infection than the adult sheep, respectively. similar observations were reported from various areas of the world (elkhatam et al., 2020; etsay et al., 2020; paul et al., 2020; kiltuet al., 2016; nourollahi-fard et al., 2016; lakew and seyoum, 2016; wang et al., 2010; maingi and munyua, 1994; kanyari, 1993). infection of sheep followed by the development of species-specific immunity, and so, sheep infected and immune to one species of eimeria may not be re-infected again by the same species of eimeria. this difference might be related to earlier infection and the development of immunity in adult sheep (matos et al., 2018; constable et al., 2017; rehman et al., 2011; yakhchali and golami, 2008). the other justification could be there is no active immunity to eimeria species in younger naïve sheep (paul et al., 2020). this study showed that eimeria infection was significantly (p< 0.05) higher in female sheep than in male sheep as also reported by various authors (elkhatam et al., 2020; etsay et al., 2020; paul et al., 2020; sharma et al., 2017; kiltu et al., 2016; khan et al., 2011; rehman et al., 2011; sharma et al., 2009; yakhchali and golami, 2008), which reported sex influences the prevalence of ovine coccidiosis. this might be attributed to sex-related factors including the physiological stress encountered by the ewe (i.e. pregnancy; lambing, and suckling the newborn lamb), which was the reason for the ewe being more susceptible to eimeria infections (heidari et al., 2014; lopes et al., 2013). a significantly higher (p< 0.05) prevalence of eimeria infection was found in semi-intensive than extensive production systems of sheep, which is also reported in various areas of the east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 40-47 45 world (de macedo et al., 2020; lakew and seyoum, 2016; kanyari, 1993). in an extensive management system, animals are freely moving in larger areas, and hence, the chance of infection is decreased as compared to the semiintensive management system. it is known that a semi-intensive management system (i.e. where high animal population density occurs) contributed to the propagation of eimeria species (de macedo et al., 2020). as the flock size of sheep increases, there is greater contamination of feeding and watering troughs (yakhchali and rezaei, 2014). hence, confinement was found to contribute to high prevalence (kanyari, 1993). in this study, a significant association was documented between body condition score and eimeria infection. similarly, lakew and seyoum (2016) and khan et al. (2011) reported a higher infection rate in sheep with poor body condition scores. the poor body condition in sheep might be due to the immunosuppressive effect of concurrent disease problems and/or nutritional scarcity. all these can negatively influence the animal feed intake and weaken the immunity, and the sheep become highly susceptible and get infected (constable et al., 2017). during this study, a significant (p< 0.05) association of eimeria species infection was observed in sheep with soft faecal consistency than the normal faeces. this finding is in a general agreement with reports from various parts of the world (khodakaram-tafti and hashemnia, 2017; lakew and seyoum, 2016; yakhchali and rezaei, 2014; yakhchali and golami, 2008). infection by most of the pathogenic eimeria species leads to the destruction of intestinal epithelial cells and induces enteritis followed by diarrhea (constable et al., 2017; chartier, and paraud, 2012; wang et al., 2010; urquhart et al., 1996). the mean oocysts count from infected animals was 2390 opg (range 300 to 12,500). the mean was meaningfully higher (p< 0.05) in lamb and young, female, and poor body condition sheep. in addition, it was statistically significant (p< 0.05) in sheep with soft faecal consistency and semi-intensively managed (table 2). higher oocyst counts were reported in lamb and/or young sheep (chartier and paraud, 2012; arslan et al., 1999; maingi and munyua, 1994; kanyari, 1993) and the semi-intensive production systems (chartier and paraud, 2012) from various areas. the negative association between opg and the age of sheep was a result of acquired immunity (kanyari, 1993). factors inducing stress, for example, increased number of animals in an area like in the semi-intensive production system, and loss of body condition might increase the oocysts output. in a nut shell, the present study revealed that the prevalence of eimeria species infection in sheep is higher. and it was significantly associated with various host-related (i.e. age, sex, body condition, and faecal consistency) and environmental factors (i.e. production system). so, this result provided useful information to design and implement appropriate control strategies. finally, it is recommended that further to study identify the species of eimeria circulating in the areas. limitation of the study the major limitation of the study was lack of facilities for eimeria spp. identification. east afr. j. biophys. comput. sci. 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(2010).prevalence of coccidial infection in sheep and goats in northeastern china. vet. parasitol., 174 (3-4): 213-217. welday k., urge m. and abegaz s. 2019. sheep production systems and breeding practices for selected zones of tigray, northern ethiopia. open j. anim. sci. 9: 135-150. yakhchali m. and golami e. 2008. eimeria infection (coccidia: eimeriidae) in sheep of different age groups in sanandaj city, iran. vet. arhiv. 78: 57-64. yakhchali m. and rezaei a.a. 2010. the prevalence and associated intensity of eimeria species infection in sheep of malayer, iran. archives of razi institute. 65 (1): 27-32. zajac a.m. and conboy g.a. 2011. veterinary clinical parasitology, 8th edition, john wiley and sons ltd, the atrium, southern gate, chichester, west sussex, po19 8sq, uk. pp. 354 . east afr. j. biophys. comput. sci., vol. 2, issue 1 *corresponding author: email: amenefe@gmail.com, +25191 1300314 ethno-veterinary medicinal plants and modes of their traditional application to cure animal ailments in adaa’liben district, ethiopia ijigu asefa1, asefa asmare2, fikru regassa3, amene fekadu2* 1 wolaita sodo university, p. o. box 138,wolaita, ethiopia 2 hawassa university faculty of veterinary medicine, p. o. box 05, hawassa, ethiopia 3 college of agriculture and veterinary medicine, p. o. box, bishoftu, ethiopia keywords: animal disease: ethno-veterinary practice; medicinal plant; traditional healer journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx 48 east african journal of biophysical and computational sciences research article cross-sectional survey of ethno-veterinary medicinal plants was carried out from november 2016 to april 2017 in ada’a-liben district, ethiopia. the purposes of the study were to identify and document medicinal plants, animal ailments treated by the medicinal plants, and modes of preparation of the medicinal plants for the treatment of animals in the study area. rapid appraisal methods were used to gather relevant information to select study kebeles and identify the 31 informants including traditional healers. information about the medicinal plants and their usage to cure various animal ailments were gathered through a semi-structured questionnaire, field observation, group discussion and market survey. thirty one ethnoveterinary medicinal plant species belonging to 23 families were used to treat 24 livestock ailments in the study area. among the medicinal plants, zingibera officinale, solanium incanum, withania somnitera, and allium sativum were used to treat blackleg and respiratory diseases whereas cypresnivies, cordia africana, celtisa africana, and vernonia amygdalina serve for deworming animals. fresh moist medicinal plants (51.6 %, n = 16/31) were the most frequently used in preparing remedies comparing to dry plants (48.4 %, n = 15/31). the widely used plant part was leaf (51.6 %) followed by fruit, seed and root (each 9.7 %) and leaf/fruit/root mixed, seed/pods, leaf/seed/stem, leaf/root, stem and bulb (each 3.2 %). the modes of preparation of medicinal plant remedies were found to be chopping (35.5 %), grinding (25.8 %), crushing (19.4 %) , decoction and using medicinal plants without processing (6.5 % each), and socking and crushing/shopping (3.2 % each). the most widely used route of administration of these remedies was oral (77.4 %) followed by topical (19.4 %) and nasal (3.2 %). eighteen species of the medicinal plants were used to traditionally treat more than one animal ailment while the remaining 13 were used to cure only one ailment each. agricultural expansion was the highest threat for the ethnoveterinary medicinal plants (51.6 %, n = 16/31) followed by drought (19.4 %, n = 6/31), soil erosion and deforestation (9.7 %, n = 3/31 each). in conclusion medicinal plants and remedies derived from them are still important and readily available source of livestock health-care to rural people in the study area. awareness creation work for traditional healers and further research on formal in-vivo and in-vitro experimental trails are suggested for a sustainable and efficient utilization of these medicinal plants. abstract mailto:amenefe@gmail.com east afr. j. biophys. comput. sci., vol. 2, issue 1 introduction the use of plants as medicine goes back to early man. evidences of this early association have been found in the grave of a neanderthal man buried 60,000 years ago. pollen analysis indicated that the numerous plants buried with the corpse were all of medicinal value. the earliest known medical document is a 4000year-old sumerian clay tab let that recorded plant remedies for various illnesses (kong et al., 2003). the recorded uses of plants as medicine are also found in babylon around 1770 bc in the code of hammurabi and in ancient egypt approximately 1550 bc. among the remedies prescribed were mandrake for pain relief and garlic for the treatment of heart and circulatory disorder. in fact, ancient egyptians believed medicinal plants to have uses even in the afterlife of their pharaohs. in 77 ad, the greek surgeon dioscorides published "de material medica", a catalog of about 600 plants in the mediterranean. it also included information on how the greeks used the plants, especially for medical purposes (acharya and anshu, 2008). the various climatic and topographic conditions of ethiopia contribute to a rich biological diversity. ethiopia is believed to be home for about more than 6,500 species of higher medicinal plants with approximately 12 % endemism (vivero et al., 2006). although modern veterinary medicine usage is gradually growing in rural ethiopia, many people are still using ethnoveterinary medicinal plants to treat their livestock ailments. this is attributed to the insufficient number of veterinarians, inadequate health facilities, and the high cost of most of the available drugs which is out of the reach of the farmers and pastoralists (giday et al., 2003). absence of response to some antimicrobial and parasitic treatment coupled with lack of adequate awareness to the usefulness of modern pharmacotherapy also compel livestock keepers particularly in rural areas to frequently visit traditional healers for getting solutions for their ill-health animals. similar to all other parts of the country, majority of the community in the study area use traditional medicines for generations to treat human and livestock ailments. still now the dependence on the traditional medicine is continuing because of its acceptability, accessibility and availability at little or no cost to the farmer. it is also believed that it is safe for it has been practiced for centuries. the use of traditional healing systems has evolved over a long period of time and the knowledge of selection of plant species for their medicinal value is not obtained over night but after many trial and error practices. those knowledgeable people don’t easily transfer their knowledge on medicinal plants usage to community where they live. instead, they want their knowledge to remain as secret and the knowledge of plant remedies remained in their hands (giday et al., 2003). when the knowledge of healing by traditional medicinal plants is passed from generation to generation, the original and valuable information passed in an incomplete fashion (elujoba et al., 2005). in addition, the knowledge is very often passed only verbally and most of this knowledge has not been comprehensively documented yet it is rapidly diminishing due to changing cultures (kedir et al., 2012). therefore, scientific research on medicinal plants enables to document the verbally passed knowledge and provides additional evidence to the present knowledge of medicinal plants which has been 49 east afr. j. biophys. comput. sci., vol. 2, issue 1 handed down from generation to generation (who, 1998). in addition, research results provide scientific based evidences on the efficacy and safety of traditional medicinal plants before using them for therapeutic purposes. this is what the modern health professionals and some of the consumers ask for. thus, unraveling the information and documentation of ethno-veterinary medicinal plants, recording the indigenous ethnoveterinary medicinal knowledge, and associated skills, practices and beliefs pertaining to animal health care builds up a strong platform for further researches aimed at developing easily accessible and affordable medicines for animal ailments. however, such information is missing in some parts of the country. to the best of our knowledge, this study is the first of its kind in the study area. therefore, the objectives of this study were to identify and document ethnoveterinary medicinal plants, the way medicinal plants are prepared and route of administration, and animal ailments treated by the medicinal plants in ada’a-liben district, ethiopia. materials and methods description of ada’a liben district ada’a liben district is one of the 12 districts in east shoa zone and is located about 45 kms south-east of the capital addis ababa and is very close to the other major urban centers. the district covers an area of 1750 km2 , stretching east of the bole international air port to the north west of the koka dam. it is located at 38° 58′e to 39° 22′e longitude, 08° 22′n to 8° 56′ n latitude and at an altitude ranging from 1500 to over 2000 meter above sea level. sedentary farming dominated by extensive type of management system is a feature of the highlands and midlands of the districts. the human population in addis ababa, adama and bishoftu create a large market for most agricultural commodities produced in the district. about 78 % of the household population who are over 10 years of age are engaged in full agricultural activities, 19.5 % in partial and 2.6 % in non-agricultural activities (gebremedhin et al., 2013). study design and methodology a cross-sectional study was carried out from november 2016 to april 2017 to identify and document the ethno-veterinary medicinal plants and the threats currently affecting medicinal plants in the study area. rapid rural appraisal (beebe, 1995) was made by conducting meetings with traditional leaders, elders, and the kebele administrators, and the state veterinary service officers at the beginning of the study to explain the purpose of the research and to gather relevant information that helps to select study kebeles (the smallest administrative unit of the country) and indentify the knowledgeable traditional healers in the study area. thus, the study sites were selected based on the availability of traditional medicinal practice as per the recommendations of the elders and local authorities in the study area. in addition, the agro-climatic zones were taken into consideration to select the study sites (kebeles). accordingly, six (qaaxilla, hiddi, qaaliti, gandagorba, calalaqa, caffee) out of 27 kebeles of the ada’a liben district were selected for ethnobotanical data collection. all the traditional healers in the selected kebeles were 50 east afr. j. biophys. comput. sci., vol. 2, issue 1 included in the study. ethno-botanical data were collected using semi-structured interviews, field observations, market observations, and group discussion. ethno-veterinary medicinal plant data collection the semi-structure questionnaire was prepared and the interview was carried out according to the method of cotton (1996). field observation on the study kebeles including the market survey was done with the help of local guide and interpreter. at the time of observation, important points including culture of the community, market value and cultivation practices of the medicinal plants were recorded. group discussions were made with 31 purposefully selected traditional healers and knowledgeable elders. the discussions were made at each study kebele in order to correct, harmonize and share the information among the respondents. those smallholder farmers, traditional healers, and knowledgeable elders who were individually interviewed were members of the group discussion. each group had five to seven members. the group discussion focused on the application of ethnoveterinary medicinal plants to cure animal ailments, parts of the plants that have medicinal values, methods of medicament preparation, routes of administration, and animal ailments treated by the medicinal plants. during the guided field walk, the traditional healers came together with the researchers to the place where the medicinal plants are found. they indicated local names and shared their ethno-medicinal knowledge, practice and beliefs on the medicinal plants. in addition, market survey and interview for herbal drug distributors and sellers was also made to distinguish the type of herbal drugs sold in the market and for which disease(s) they are indicated. moreover, semi-structured questionnaires were used to document knowledge and skills of traditional healers and knowledgeable elders about the plants used for treatment of livestock diseases. an interview was also held with a professional veterinarian to confirm diseases referred to by the farmers and traditional healers. then, the medicinal plants were collected after recording all the important information obtained from the traditional healers and farmers. in order to confirm the reliability of the information, each informant was contacted at least twice and if the responses that were given at different times contradict to each other, the information was considered to be unreliable and was rejected. in addition, reliability of the information was assessed and confirmed when information given by different informants on the same issue was similar. plant specimen collection and identification medicinal plant species were collected under the guidance of the traditional healers from the wild and home gardens. pictures of the plants were taken with a digital camera. one specimen of each plant species was collected and pressed according to the methods of fish (1999). the collected plants and the necessary recorded information were taken to the national herbarium of biology department in addis ababa university, ethiopia (annex 1 & 2). after the specimens were taken to the department, plant species were identified using taxonomic keys following protocol mentioned on the flora of ethiopia and eritrea (edwards 51 east afr. j. biophys. comput. sci., vol. 2, issue 1 et al., 2000; hedberg et al., 2006) and by making a comparison with the already identified specimens that were deposited at the biology department national herbarium. data analysis descriptive statistical methods (proportions or percentiles) were used to summarize the collected ethno-veterinary medicinal plants data. microsoft excel and spss (statistical package for social science) version 20 software were used for the data analysis. results informants and their characters out of the 31 informants, 27 (87.1 %) were male, whereas 4 (12.9 %) were females. twelve (38.7 %) were traditional healers and 18 (58.1 %) were farmers (table 1). table1: general characteristic of the informants at the study area variable character count/response percentage (%) sex male 27 87.1 % female 4 12.9 % age young 3 9.7 % adult 28 90.3 % educational status illiterate 21 67.7 % literate 10 32.3 % marital status occupation married 24 77.4 % single traditional healers farmers others 7 12 18 1 22.6 % 38.7 % 58.1 % 3.2 % sources, type, and seasonal availability of medicinal plants the data collected from the study sites showed that most of the ethnoveterinary medicinal plants were collected from the wild (n = 16/31; 51.6 %) and others were from home gardens (n = 15/31; 48.4 %). in addition, regarding the type of the plants, 13 (49.9 %) were herbs and 10 (32.3 %) were trees. ethno-veterinary medicinal plants found in the study area were affected by season; many of the plants were available in every season (81.3 %, n = 28/31) while some are available seasonally (12.5 %, n = 2/31), and the rest are difficult to find at any season (6.3 %, n = 1/31). medicinal plant parts used as a medicament, mode of preparation, and route of administration the study showed that the widely used plant part for the preparation of the remedies in the study area was leaves (51.6 %) and followed by other parts of the plant (fruit, seed and root) or a combination of these parts (table 3). the study 52 east afr. j. biophys. comput. sci., vol. 2, issue 1 revealed that the highest mode of preparation of medicinal plants for animal treatment was in the form of chopping (35.5 %); followed by grinding (25.8 %), crushing (19.4 %), and other methods (table 2). table2: modes of preparation of the ethnoveterinary medicinal plants for animal treatment no; scientific name family name local name preparations 1 cypresnivies cypraceae quunii grinding 2 euphorbia ampliphyllapex euphorbiceae adaamii grinding 3 cordia africana boraginaceae wadeessa chopping 4 achyranthes bidentata amaranthaceae maxxaanee chopping 5 azadiracta indica meliaceae mimii grinding 6 calpurnia aurea fabaceae ziigixaa socking 7 allium sativum alliaceae qullubiiadii grinding 8 brassica carinata brassicaceae gomeenzera chopping 9 ocimum lamifolium lamifoliumceae masoobila decoction 10 celtis africana ulmaceae ceekkata chopping 11 withania somnitera solanaceae mimmiixa grinding 12 carrissa spinarum apocynaceae hagamsaa crushing 13 coffea arabica rubiaceae buna grinding 14 croton macrostachyus euphorbiaceae makaniisaa grinding 15 dracaena steudneri draceanaceae afarfattuu chopping 16 rhammus prinoides rhamnaceae geeshe chopping 17 justicia schimperiana acanthaceae dhumugaa chopping 18 nicotiana tabacum solanaceae taamboo chopping 19 aloe vera asphodeiaceae harmagusaa crushing/chopping 20 phragmanthera macrosolen loranthaceae dheertuu chopping 21 ricinus communis euphorbiaceae qobboo crushing 22 solanium incanum solanaceae hiiddii grinding 23 achyranthes aspera amarantaceae daarguu chopping 24 vernonia amygdalina asteraceae eebicha as it is 25 ocinum lamifolium lamifoliumceae damakase crushing 26 carica papaya caricaceae papaya crushing 27 sorghum bicolar poaceae mishingaa as it is without 28 citrus aurantifolia rutaceae loomii crushing 29 vernonia auriculifera asteraceae giraawa chopping 30 clausena anisata rutaceae uluma’ii decoction 31 zingibera officinale zingebiraceae jinjiibila crushing fresh moist medicinal plants (82.5 %) were the most frequently used to prepare remedies comparing to dry medicinal plants (17.5 %). the most widely used route of administration was oral, which accounted for 77.4 % followed by topical (19.4 %) and other routes (3.2 %) (table 3). 53 east afr. j. biophys. comput. sci., vol. 2, issue 1 table -3: the use of ethnoveterinary plants for the treatment of animal ailments i. herbs scientific name local name part routes indications cypresnivies quunii root oral deworming of equidae euphorbia ampliphyllapex adaamii stem topical blackleg achyranthes bidentata maxxannee fruit oral blackleg, mastitis and bleeding allium sativum qullubbiiadii bulb oral abdominal pain, blackleg, leech, respiratory disease and bloat brassica carinata gomeenzeraa seed oral bloat ocimum lamifolium masobiilaa leaf oral appetizer and spice withania somnifera miimmiixaa seed/pods oral abdominal pain, bloat, black leg, respiratory disease, leech infestation rhammus prinoides geeshee leaf oral leech and tick infestation aloe vera harmaguusaa leaf topical weaning of calf solanium incanum hiiddii leaf/root and fruit oral black leg, respiratory disease and dermatophilosis ocimum lamifolium damakaase leaf oral blackleg and ‘dingetegna’ sorghum bicolar miishingaa seed oral retained placenta zingibera officinale jinjibiilaa root oral blackleg, respiratory disease, abdominal pain and leech ii. trees, shrubs and climbers scientific name local name part routes indications cordia africana wadeessa leaf oral deworming of equidae azadiracta indica miimii leaf oral blackleg, trypanosomosis and abortion calpurnia aurea ziigixaa seed topical lice infestation celtis africana ceekkataa leaf oral/topical/nose lice infestation, leech, diarrhea and git parasite carrissa spinarum hagamsa root oral ring worm, wound coffea arabica buna fruit topical wound croton macrostachyus makkanniisa leaf oral/topical ring worm, bloat, wound dracaena steudneri afarfattuu leaf oral rabies justicia schimperiana dhummuugaa root/leaf oral black leg, rabies nicotiana tabacum taamboo leaf oral leech infestation and bloat phragmanthera macrosolen dheertuu leaf oral bloat, blackleg ricinus communis qobboo friut oral retained fetal membrane, rabies, headache(human) achyrentes aspera daarguu leaf oral abdominal discomfort & febrile disease vernonia amygdalina eebiichaa leaf oral increase milk production carica papaya papayaa leaf topical wound treatment citrus aurantifolia loomii fruit topical tick infestation and wound vernonia auriculifera giiraawa leaf oral anti parasite and abdominal pain clausena anisata uluma’ii leaf oral poultry coccidiosis 54 https://en.wikipedia.org/wiki/withania_somnifera https://www.google.com/search?sxsrf=alekk030coidy2kbilszb3srufzhp7in1g:1624298114597&q=ocimum+lamifolium&spell=1&sa=x&ved=2ahukewi7rysbpqnxahujhxokhxjodnoqkeeckab6bagbec4 east afr. j. biophys. comput. sci., vol. 2, issue 1 livestock diseases treated and plant families frequently used for the treatment according to our findings, there are a total of 23 known livestock ailments/diseases in the study area, which are treated by traditional healers. of the diseases, blackleg was treated by 32.3 % of the medicinal plants (n = 10), leech by 19.4 % (n = 6), bloat by 19.4 % (n = 6), wound by 16.1 % (n = 5), abdominal pain or colic by 16.1 % (n = 5), respiratory disease by 12.9 % (n = 4), git helminthes by 12.9 % (n = 4), ectoparasites by 12.9 % (n = 4) (table 4). table -4: livestock ailments and number of ethnoveterinary plants used to treat them diseases treated local name of the disease no of ethnoveterinary plant used deworming of git helminthes ciniintobeylada 2 wound madaa 5 blackleg abba gorba 10 ring worm roobbii 2 abdominal pain garaaciinina 2 bleeding lola’udhiiga 1 respiratory diseases gororsaa 4 trypanosomosis gaandii 1 mastitis dhiita’uu guru 1 leech ulaandhula 6 bloating bokoksaa 5 dermatophilosis gogaaharcaas 1 rabies sareemaraatu 3 lice infestation hinjiran 2 coccidiosis mugsiisalukku 1 git parasites diarrhea maxxantoota garaakaasa 1 1 tick infestation silmiihorii 2 fuminant ailment dhukkubatasa 1 febrile disease ho’iinsaqaama 1 delayed weaning of calves harmaadhabsiisu 1 to increase milk production anaandabaluf 1 abortion gatachiisa 1 in this ethnoveterinary medicinal plant survey, thirty one medicinal plants species belonging to twenty three families were recorded in the study area. of the plants solanaceae and euphorbiaceae families constituted the highest proportion (10.9 % n = 3/23 each) and followed by rutaceae, amaranthaceae, asteraceae and lamifoliumceae with the same proportion (7.3 %, 2/23 each), all the rest seventeen families constituted a proportion of 3.7% (n = 1/23 each) (table 5). 55 east afr. j. biophys. comput. sci., vol. 2, issue 1 table5:medicinal plant families frequently used by traditional healers family name no of ethno-veterinary plant species used proportion (%) cypraceae 1 3.7 % boraginaceae 1 3.7 % apocynaceae 1 3.7 % euphorbiaceae 3 10.9 % amaranthaceae 2 7.3 % rubiaceae 1 3.7 % lamifoliumceae 2 7.3 % acanthaceae 1 3.7 % asteraceae 2 7.3 % poaceae 1 3.7 % caricaceae 1 3.7 % loranthaceae 1 3.7 % draceanaceae 1 3.7 % asphodeiaceae 1 3.7 % rhamnaceae 1 3.7 % ulmaceae 1 3.7 % meliaceae 1 3.7 % fabaceae 1 3.7 % rutaceae 2 7.3 % brassicaceae 1 3.7 % alliaceae 1 3.7 % zingebiraceae 1 3.7 % solanaceae 3 10.9 % threats to ethnoveterinary plants and necessity of their conservation in the group discussion, it was revealed that agricultural expansion is the highest threat for the ethnoveterinary medicinal plants (51.6 %, n = 16/31) followed by drought (19.4 %, n = 6/31), soil erosion and deforestation (9.7 %, n = 3/31 each). over grazing (3.2 %, n = 1/31) was the least threat for ethno-veterinary medicinal plants in the study area (table 6). the study indicated that many of the informants who have knowledge on traditional medicine usage give priority to the immediate use of the medicinal plants than to its sustainable future uses, as a result their harvesting style is destructive. however, some medicinal plants have been protected because they are multipurpose. in addition to ethno-veterinary remedies, they also serve as spices, cash crop, food, live fence, or other purposes. 56 east afr. j. biophys. comput. sci., vol. 2, issue 1 table -6:priority ranking of factors perceived as threat to ethno-veterinary plants transfer of knowledge about the ethnoveterinary medicinal plants and practices in the group discussion, the highest number of attendants/respondents agreed that the transfer of knowledge of traditional medicine is to trusted eldest son (36%, n = 11/31) followed by trusted sons (25.5%, n = 8/31), all members of the family (18.5%, n = 6/31), relatives (12%, n = 4/31), and friends (8%, n = 2/31). during the group discussion, it was evidenced that as people become older and older their knowledge of traditional medicine becomes better and better. it was also observed that there was no much trading on medicinal plants in the study area though very few practitioners and women sell some medicinal plants in the market and at their homes for medical purposes with a very low price. some of the medicinal plants that are grown at home gardens and often sold as ethnoveterinary remedies, spices and other purposes are allium sativum, nicotiana tabacum, zingiber officinale, capsicum annum, coffea arabica. the group discussion also revealed that there is no standardized known unit of measurements of the plant remedies. this means that the same types of ethnoveterinary medicinal remedies for the same types of ailments were given with different measurements in the same or different kebeles of the study area. but, higher dosage was given for severe diseases. discussion medicinal plants belonging to 23 families and 31 species were being used extensively for curing 24 animal ailments commonly found in the study area. these ethnoveterinary medicinal plants were documented with their scientific, local, and family names. their type, traditional preparation methods, and route of administration for treating animal ailments were also recorded. medicinal plant species belonging to solanaceae and euphorbiaceae families were relatively abundant in the study area followed by rutaceae, asteraceae, lamifoliumceae and amaranthaceae. plants under the families solanaceae, euphoraceae, rutaceae, asteraceae were also used as ethnoveterinary remedies in zimbabwe (nyahangare et al., 2015), whereas solanaceae and euphorbiaceae in south africa (luseba and van der merwe, 2006), and solanaceae, asteraceae, zingiberaceae, and rutaceae in india (phondani et al., 2010). acording to yigezu et al. (2014), asteraceae, cucurbitaceae and solanaceae make up larger proportion of medicinal plants used in jimma zone, ethiopia. factors frequency percentage (%) rank agricultural expansion 16 51.6 % 1 drought 6 19.4 % 2 soil erosion 3 9.7 % 3 deforestation 3 9.7 % 3 low cultivation 2 6.5 % 4 over grazing 1 3.2 % 5 total 31 100 % 57 east afr. j. biophys. comput. sci., vol. 2, issue 1 the study revealed that medicinal plants are still important, readily available, and cheap source of animal health-care remedies to livestock raisers in the study area. the high cost of pharmaceutical products and limited access to veterinary services probably were among the reasons for farmers to use the traditional ethnoveterinary medicinal plants as means of keeping their animals healthy and productive. the same species of medicinal plants found in the study area were also used to cure animal ailments elsewhere in the world. farmers in the study area used nicotiana tabaccum for the treatment of leech infestation and bloat whereas, in zimbabwe, kenya, and appalachia of rural north america, it was used as acaricide to treat ectoparasites mainly ticks, lices, and bots (gakuubi and wanzala, 2012; nyahangare et al., 2015; terrel, 2015, respectively). in jimma zone, south west ethiopia, nicotiana tabaccum is widely used by farmers for the treatment of snake bite, blackleg and for fattening purpose (yigezu et al., 2014). zingibera officinale was remedies for abdominal pain or colic in the study area. it was also used in india (singh et al., 2012) and appalachia of usa (terrel, 2015) for the same purpose;. herbalists in the study area and india (singh et al., 2012) applied allium sativum for the treatment of colic and bloat among others while in ghana, mali, niger, and nigeria it was used for the cure of fever (adedeji et al., 2013). there was similar usage of solanum incanum as a remedy for blackleg in the study area, ghana, nigeria, niger, and mali (adedejiet al., 2013), and skin disease in the study area and kenya (gakuubi and wanzala, 2012). another ethnoveterinary medicinal plant, azadiracta indica was used for curing blackleg in the study area and india (sajal et al., 2016). on the other hand, the same medicinal plant was used in kenya (gakuubi and wanzala, 2012) and senegal (adedeji et al., 2013) to deworm animals. aloe verae was used for deworming animals in zimbabwe (matekaire and bwakura, 2004) and for treating diarrhea in somalia (adedeji et al., 2013), and for delayed weaning of calves in the study area. diarrhea and delayed weaning of calves may mostly be connected with helminthiasis because most of the calves in the rural areas of the said countries totally depend on grazing as source of their feed where they can easily acquire parasites. most of the medicinal plants in the study area were available always, while some were found seasonally mainly during the rainy season. about 6% of the medicinal plants were at the verge of extinction probably due to expansion of agriculture in which most of the bushes and forests were destroyed to grow crops and the remaining land was overgrazed. traditional healers in the study area gather medicinal plants of different plant group (41.9 % herbs and 32.3 % tree) from the wild and/or home gardens. increased number of medicinal plants was collected from the wild comparing to the home garden. similar finding was recorded by tamene (2000), giday (2003), and awas and demissew (2009). this may indicate the necessity of conserving medicinal plants because those plants in the wild are at the risk of extinction. according to demisse (2001), the biodiversity of ethiopia is eroding by natural and anthropogenic pressures, the later being predominant in urban and peri-urban areas. most medicinal plants were collected when needed but some were dried, ground and stored in the form of powder. in general, fresh moist medicinal plants were the most frequently used in preparing remedies comparing to dried plants. 58 east afr. j. biophys. comput. sci., vol. 2, issue 1 this is in agreement with the finding of balemie et al. (2004). this might be because fresh moist medicinal plants were more effective remedy than dried ones and drying probably decreased active ingredients and hence the efficacy of remedies extracted from medicinal plants. leaves, roots, seeds and fruit from the documented medicinal plants were used to prepare remedies. leaves were the most frequently used parts in the study area particularly for 18 medicinal plants used, followed by roots for five, and seeds for four and fruits for other four medicinal plants. this finding is in agreement with the finding of giday et al. (2003), mesfin (2007), yigezu et al. (2014) and abera and mulate (2019) . leaves of most medicinal plants were used to process remedies probably because they are collected without affecting sustainability of the medicinal plants and further they may contain more medicinally valuable ingredients that make them more effective than the other plant parts. moreover, the use of leaves compared to their roots is advantageous to protect the plants from extinction. the end products of the traditional medicinal remedies were prepared by grinding, crushing decoctions, chopping, roasting, and pounded forms. then, most of the plant remedies were administered orally (77.4%) followed by topical (19.4%) and intra nasal (3.2%). similar route of administration of medicinal plant remedies was registered by abebe and ayehu (1993), teklehaymanot and giday (2007), teshale et al. (2004), yigezu et al. (2014). the group discussion revealed that there was no standardized known unit of measurements of the plant remedies. this means that the same types of ethno-veterinary medicinal remedies may be given for the same types of ailments perhaps with different measurements in the same or different kebeles of the study area. however, respondents of the current study and reports on previous studies argued that higher dosage was given for severe diseases. most of the traditional ethnoveterinary knowledge is not yet documented particularly in the study area and the country at large. it is passed on orally from generation to generation. the healers pass the knowledge to the family member only when they are unable to prepare the remedies by their own particularly when they get very old or critically sick. this might be the reason why elders are important source of the ethno-veterinary knowledge in this study. conclusion thirty one medicinal plants species belonging to 23 families were used to traditionally treat 24 livestock ailments including blackleg, wounds, leeches and rabies among others. most of the medicinal plants, majorly their leaves, were gathered by traditional healers from the wild and about 6% of the medicinal plants are at the verge of extinction. crushed leaves of fresh moist medicinal plants mixed with water were primarily administered through oral route as a preferred ethno-veterinary remedies. however, there was no standardized known unit of measurements (dose) of the plant remedies for the treatment of animal diseases in the study area. although, medicinal plants are still important, readily available, and cheap source of animal health-care remedies to livestock raisers, they have not yet received good attention by the researchers. their efficacy has not been tested through formal in-vivo and in-vitro experimental trails on which more work is required. for efficient and sustainable use of these plants, 59 east afr. j. biophys. comput. sci., vol. 2, issue 1 particularly those endangered, awareness creation is required for traditional healers. acknowledgements the authors fully acknowledge the national herbarium of biology department in addis ababa university for their willingness to identify the collected plant samples. we also extend our deepest gratitude for the local guides, interpreters, informants (traditional healers and knowledgeable elders) for their valuable time and shared information. references abebe d. and ayehu a. 1993. medicinal plants and enigmatic health practices of northern ethiopia. b.s.p.e. addis ababa. abera y. and mulate b. 2019. ethno-veterinary medicine: a potential alternative to animal health delivery in wolmera district, oromia region, ethiopia. ethiop. vet. j. 23 (1): 111130. acharya d. and anshu s. 2008. indigenous herbal medicines: tribal formulations and traditional herbal practices. avishkar publishers distributor, jaipur, india. isbn 978–81–7910– 252–7, 2008, p. 440. adedeji o. s.,ogunsina t.k.,akinwuni 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d. 2006. progression the red list of plants of ethiopia and eritrea.conservation and bio-geography of endemic flowering taxa. in: ghazanfar s.a. and beentje h.j. (eds.) taxonomy and ecology of african plants, their conservation and sustainable use. proceedings of the 17th aetfat congress. addis ababa, ethiopia, pp 761–778,. royal publishing, kew. world health organization (who) 1998. regulatory situation of herbal medicines: a world wide review,geneva, pp 1—9. yigezu y., haile d.b. and ayen w.y. 2014. ethnoveterinary medicines in four districts of jimma zone, ethiopia: cross sectional survey for plant species and mode of use. bmc veterinary research 10:76. http://www.biomedcentral.com/17466148/10/76 61 http://www.biomedcentral.com/1746-6148/10/76 http://www.biomedcentral.com/1746-6148/10/76 east afr. j. biophys. comput. sci., vol. 2, issue 1 annex 1: different medicinal plants commonly used by traditional healers in adaa’liben district (a) euphorbia ampliphyllapex l; (b) dracaena steudneri l; (c)coffe arabica l; (d)celtisa africana l; (e) achayrentes bidentata l; (f) ocinum lamifolium l; (g) phragmanthera macrosolen l; (h) justicia schimperina l; (i) vernoni amygdalina l; (j) rhammus pirnoides l; (k) vernoni amygdalina l; (l) brassica carinata l; (m) carrisas pinarum l; (n) aloe vera l; (o) solanium incanum (l); (p)azadiracta indica a b e f i j m n o p k l g h c d 62 east afr. j. biophys. comput. sci., vol. 2, issue 1 annex 2: different medicinal plants commonly used by traditional healers in adaa’liben district (q)zingibera officinale l; (r) citrus aurantifolia l; (s)ocimum lamifolium l; (t) achyranthes bidentata l; (u) croton macrostachyus l; (v) clausena anisata l; (w) withania somnitera l; (x) sorghum bicolor l; (y) carica papaya l; (z) ricinus communis l; (a1) allium sativum l; (a2) cypresnivies l; (a3) nicotiana tabacuml; (a4) cordia africanal; (a5)calpurnia aurea l. q r u v x z a3 a4 a5 a1 a2 y w s t 63 cover v2.pdf (p.1) cover.pdf (p.1-2) slide number 1 blank page.pdf (p.2) table of contents vo 2.pdf (p.3-5) all articles vol 2.pdf (p.6-81) volume 2 issue 1_ 6 articles_4_3.pdf (p.6-91) 4_captive fish_anna results and discussion references 3_reproductive disorder 6_diet bredth_prof. nat 8_ground water_jeeva base boundary map was prepared using survey of india topo-sheets of the study area, and data such as rainfall, geomorphology, geology and land use were collected from central and state government agencies. during field study, groundwater samples were ... 10_ethnoveterinary following comments dagne et al_ challenging students’ performance through practical skills assessment.pdf (p.73-82) guideline to authors_ eajbcs.pdf (p.82-90) back cover.pdf (p.91) introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction *corresponding author: email: amenefe@gmail.com; +251 -91 130 0314 seifemichael ushencho1 & amene fekadu2* 1tocha woreda animal and fisheries development office , dawro zone, tocha, ethiopia 2faculty of veterinary medicine, hawassa university, p.o.box 05, hawassa, ethiopia keywords: trypanosomiasis; kindo koysha; t. congolense; bovine abstract introduction in ethiopia, agricultural development is considered a priority by the government for stimulating overall economic growth, reducing poverty and achieving food security. the agricultural sector of ethiopia accounts for about 42% of gdp and between 80–85% of employment (mofed, 2012). within agriculture, the livestock subsector provides an opportunity for further development. the sheer size of the national livestock herd, one of the largest in africa, makes it a resource with potential to contribute journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx east afr. j. biophys. comput. sci., vol. 1, issue. 1 23 prevalence and community awareness of bovine trypanosomiasis in wolaita zone kindo koysha woreda, southern ethiopia east african journal of biophysical and computational sciences research article a cross-sectional study was carried out from october 2018 to april 2019 in kindo koysha woreda of wolaita zone, southern nation nationalities and people region (snnpr), ethiopia. the general objectives were to find the prevalence and assess the community awareness on bovine trypanosomiasis and to identify predominant trypanosome species. blood from marginal ear vein was collected from a total of 220 cattle for packed cell volume (pcv) determination and trypanosome detection. accordingly, the overall prevalence of bovine trypanosomiasis in the area was 5.91% on buffy coat examination. of which, 61.57% (n=8), 30.76% (n=4) and 7.69% (n=1) were because of t. congolense or t. vivax or both species, respectively. the mean pcv values recorded were 23.77% in parasitemic and 28.27% in aparasitemic animals. the focus group discussion indicated that trypanosomiasis (shulula) is the most important problem affecting the animals and hindering agricultural activity in the area. generally, both focus group discussion and hematological findings revealed bovine trypanosomiasis is the major constraint for the livestock production in the area. so attention should be given to control trypanosomiasis and its vectors. mailto:amenefe@gmail.com east afr. j. biophys. comput. sci., vol. 1, no. 1 significantly to national development, including poverty reduction. the central statistical agency (csa) survey of 2016 showed that the total cattle population of ethiopia is about 59.5 million. moreover, about 30.7 million sheep and 30.2 million goats are estimated to be found in the country, while the total poultry population is estimated to be about 59.5 million chickens (csa, 2016). the livestock subsector is also already a major contributor to the overall economy. the livestock sector contributes 19% of the gdp, and 16–19% of the foreign exchange earnings of the country (moa 2012). it contributes some 35% of agricultural gdp; or 45% if indirect contributions are taken into account (shapiro et al., 2017). with a rapidly growing population, increasing urbanization, and rising incomes, domestic demand for meat, milk and egg is expected to increase significantly in the foreseeable future. furthermore, the country’s geographic location offers substantial opportunities for exportation, thus earning foreign exchange from livestock products, especially of red meat to the gulf and within africa, as well as leather, honey and other livestock products to europe(shapiro et al., 2017). the livestock sector can also be a major contributor to poverty reduction by improving the livelihoods of rural people. approximately 85% of ethiopia’s population is rural based, and livestock supports the livelihoods of about 80% of rural people (shapiro et al., 2017). however, the income of 30% of the rural population is below the poverty line (mofed, 2013). livestock perform multiple functions in the rural household economy. besides employment, livestock provides protein rich food, income for everyday expenses and social obligations, near liquid assets, a store of wealth for savings, manure for crop production and soil fertility, and transport (shapiro et al., 2017). livestock development also has the potential to positively impact urban consumers through lower animal product prices. despite large livestock population, ethiopia fails to optimally utilize this resource due to different constrains facing the livestock subsector. shortage of nutrition, reproductive insufficiency, management constraints and animal disease are the major constraints. one of the diseases hampering the livestock subsector is trypanosomiasis (melak and tewodros, 2018). trypanosomiasis is a widely spread protozoan disease complex which affects cattle and other wide range of hosts in sub saharan africa. the major pathogenic tsetse transmitted trypanosome species are trypanosome congolense, t.vivax and t. brucei in cattle, sheep and goats and t. simiae in pigs. animal trypanosomiasis is also encountered outside the tsetse fly belt, where the most important pathogenic trypanosome species, t. vivax and t. evansi, are transmitted mechanically by biting flies, while t. equiperdum is transmitted sexually. the principal domestic animals affected by t. evansi are camels, pigs, water buffaloes and cattle. t.equiperdum causes the disease in horses and donkeys (nantulya et al., 1986). the course of the disease may run from a chronic long lasting to an acute and rapidly fatal depending on the vector-parasite-host interactions. the disease is mainly characterized by intermittent fever, progressive anaemia, and loss of condition of susceptible hosts which if untreated leads to heavy mortalities (bourn et al., 2001). 24 east afr. j. biophys. comput. sci., vol. 1, no. 1 in ethiopia, trypanosomiasis is widespread in domestic livestock in the western, south and south western lowland regions and the associated river systems (abay/dedessa, ghibe/omo and baro/akobo and rift valley) (abebe, 2005), limiting livestock productivity and agricultural development in the country. currently, about 220,000 km2 areas of fertile land are infested with five species of tsetse flies namely glossina pallidipes, g.morsitans morsitans, g. fuscipes, g. tachinoides and g. longipennis (ntticc, 2004). six species of trypanosomes are recorded in ethiopia and the most trypanosomes, in terms of economic loss in domestic livestock are the tsetse transmitted species: t. congolense, t. vivax and t. brucei group (abebe, 2005). trypanosomiasis was considered to be an important disease of cattle in different parts of the country (mussa, 2002; tesfaye, 2002; cherenet et al., 2004; sinshaw, 2004; shimelis et al., 2005; bitew et al., 2011). even though, trypanosomiasis is an economically important disease, few studies were done in ethiopia as well as in wolaita zone kindo koysha woreda. therefore, this study was conducted to determine the prevalence of bovine trypanosomiasis, to identify predominant trypanosome species involved and to recognize indigenous knowledge and correlate it with modern science in kindo koysha woreda. materials and methods description of the study area: the study was conducted in kindo koysha woreda of wolaita zone, southern region of ethiopia. it is located at about 420 km of south west of addis ababa located at 7°58” n and 37°14” latitude and 37°56” e longitude and it has an altitude of 600-1700 meters above sea level. and its total area is estimated to be 17,187 hector of land. the distribution of rain is bimodal, with short rainy season extend from january to april and long rains from june to mid-september. the average annual rainfall is 904 mm, the maximum and minimum daily temperature is 29.20 and 21°c respectively. the vegetation is savanna type with scattered bush. the livestock populations that are found in kindo koysha woreda include cattle, sheep, goat, horses, mule, donkey and poultry. among these animals, cattle are the dominant species raised in the area and are estimated to be 174,346 (csa, 2009). study design, sample size and sampling method: cross sectional study was conducted to determine the prevalence of bovine trypanosomiasis. 95% confidence interval and 5% precision was considered to calculate the sample size and 6.3% expected prevalence was taken (adale and yasin, 2013). the sample size was determined by using the formula given by thrusfield (2005). even though the sample size was calculated to be 91, a total of 220 animals were included in the current study to increase precision. study population: cattle population of kindo koysha woreda which is managed under traditionally reared management system was selected to determine the prevalence of bovine trypanosomiasis. both local/indigenous and exotic breeds of cattle in the study area (dada kariya, fajanamata, moliticho) were considered as study population. the study animals were selected by using 25 east afr. j. biophys. comput. sci., vol. 1, no. 1 random sampling method by taking breed, age, sex and body condition into account. the animals examined were categorized into different age groups as less than 2 years (young), between 2 and 4 years (medium) and greater than 4 years (adult) according to their teeth dentition (johnson, 2003). the body condition of animals was also grouped based on criteria described by nicholson and butterworth (1986) and they also categorized into poor, medium and good. study methodology parasitological and hematological survey of bovine trypanosomiasis: buffy coat technique: blood was collected from an ear vein using heparinized micro haematocrit capillary tube and the tube was sealed. a heparinized capillary tube containing blood was centrifuged for 5 min at 12,000 rpm. after centrifugation, trypanosomes were usually found in or just above the buffy coat layer. the capillary tube was cut using a diamond tipped pen 1 mm below the buffy coat to include the upper most layers of the red blood cells and 3 mm above to include the plasma. the content of the capillary tube was expressed on to slide, homogenized on to a clean glass slide and covered with cover slip. the slide was examined under ×40 objective for the movement of parasite (paris et al., 1982). measuring of packed cell volume (pcv): blood samples were obtained by puncturing the marginal ear vein with a lancet and collected directly into a capillary tube. the capillary tubes were placed in micro haematocrit centrifuge with sealed end outer most. the tube was loaded symmetrically to ensure good balance. after screwing the rotary cover and closing the centrifuge lid, the specimens were allowed to centrifuge at 12,000 rpm for 5 min. tubes were then placed in haematocrit and the readings were expressed as a percentage of packed red cells to the total volume of whole blood. animals with pcv < 24% were considered to be anemic (murray et al., 1988). focus group discussion: rural communities have a wealth of indigenous knowledge and skills related to diseases, including good diagnostic skills and an awareness of modes of disease transmission. it is imperative to make the best use of this knowledge and develop appropriate disease surveillance systems in rural areas. such systems should be action oriented and result in disease control activities that are designed in partnership with livestock keepers (catley, 2005). this study used focus group discussion technique to collect epidemiological information and intelligence about diseases of livestock especially bovine trypanosomiasis. the focus group discussion incorporated eight groups having 8-12 participants in each group. data management and analysis tools: raw data on individual animals and parasitological examination results were stored in ms excel spread sheets to create data base and transferred to stata 11 software programs for data analysis. chi square was used to compare the prevalence of trypanosome infection in different variables like kebeles / village, breed, age, sex and body condition, 26 east afr. j. biophys. comput. sci., vol. 1, no. 1 while student-t test was utilized to compare the mean pcv of the infected animals and that of non-infected animals. significance difference was set at p < 0.05 and 95% confidence level. results results of focus group discussion: according to the data from the group discussion, trypanosomiasis is the predominant livestock disease in the kindo koysha followed by babesiosis (14.75%), blakleg (13%) and others (table 1). table-1: common cattle diseases with its respective proportional disease prevalence % shulula (trypanosomiasis) 35 tilikiya/tintichuwa (blackleg) 13 duluwa (anthrax) 6.375 aheera (babesiosis) 14.75 shattuwa (skin diseases) 8.125 danquwannecuuchcha (tick and lice infestation) 7.5 ullogiddoguxxuniya (git parasite) 7.625 duma dummahargiya (others) 7.625 based on the response of the rural communities, the prevalent diseases in the area cause direct and indirect negative impacts on the cattle and their products (table 2). table-2: negative impacts of diseases on the animals and animal’s product diseases milk (%) meat (%) skin (%) dowry (%) abortion (%) decrease price (%) treatment cost (%) total loss (%) trypanosomiasis 23 14.5 1.5 9 10.75 13 24.5 3.75 blackleg 6.25 5 1.75 1.75 2 34.5 48.75 anthrax 1 99 babesiosis 27 17.5 3 5 12.5 7 20 8 skin diseases 15 12 23 9 20 21 tick & lice infestation 21 16.25 16.75 8 2 18 17 1 git parasite 24 22.5 7 15 31.5 others diseases 15.5 12.5 5 6 11 8 22 20 according to the wolaita culture the year is divided into three seasons such as boniya (bega) which includes the months from october to february, badheessa (belg) from march to may and silla (summer) which contains months from june to september. according to the respondents, the prevalent diseases in the area have different seasonality however majority of these diseases were observed during ‘belg’ and summer (table 3). 27 *corresponding author: email: amenefe@gmail.com; +251 -91 130 0314 table-3: disease occurrence in the different seasons of the year and age group of cattle disease age group season calf (%) young (%) adult (%) ‘bega’ (%) ‘belg’ (%) summer (%) trypanosomiasis 10 29 61 39.6 33.7 26.7 blackleg 7.5 36 56.5 9.55 53.75 36.7 anthrax 6 33 61 7.5 63 29.5 babesiosis 12 31 57 19 49.5 31.5 skin diseases 14 40 46 37 30.5 32.5 tick and lice infestation 35 34 31 20 50 30 git parasite 37 28 35 20 50 30 others diseases 20 35 45 22 50 27 the major actions taken by the society to overcome the impacts of the prevalent diseases are detailed in the table 4. table4. major disease prevention and control measures applied in the study area. disease vaccination (%) spraying (%) drug (%) traditional medicine (%) trypanosomiasis 38 62 blackleg 50 37 13 anthrax 96 4 babesiosis 4 3 68 25 skin diseases 29 25 46 tick and lice infestation 72 25 3 git parasite 95 5 others diseases 44 8 41 7 results of parasitological survey: prevalence: in this study a total of 220 cattle were examined for the presence of bovine trypanosomiasis. out of these 220 cattle; 13 were found to be positive for bovine trypanosomiasis that results in the overall prevalence of 5.9%. of which 61.57% were due to t. congolense and 30.76% were due to t. vivax whereas the rest 7.69% were due to mixed infection (table 5). but there was no significant difference (p>0.05) between the prevalence of the different trypanosome species. 28 mailto:amenefe@gmail.com east afr. j. biophys. comput. sci., vol. 1, no. 1 table -5. relative proportion of trypanosome species in the three kebeles kebeles number positive trypanosome species , n(%) proportion (%) χ2 pvalue t.congolense t.vivax mixed fajenamata 7 4(30.77) 2(15.38) 1(7.69) 53.8 1.58 0.813 moliticho 5 3(23.08) 2(15.38) 0 38.46 dadakariya 1 1(7.69) 0 0 7.69 total 13 8(61.57) 4(30.76) 1(7.69) 100 the highest prevalence of trypanosome infection was found in fajenamata kebele (7%) followed by moliticho (6.94%) and dadakariya (2.08%). however, there was no significant difference (p>0.05) in the prevalence among the kebeles (table 6). the prevalence of trypanosomiasis in male and female cattle were 5.31% and 6.54% respectively (table 6). however, the difference in the prevalence between the two sexes was found to be statistically insignificant (p>0.05). table6. prevalence of trypanosome infection among the categories of the considered risk factors variables number examined number positive prevalence (%) 95% ci kebeke fajenamata 100 7 7.00 1.95 – 12.05 moliticho 72 5 6.94 1.00 – 12.89 dadakariya 48 1 2.08 -2.02 – 6.19 age < 2 years 15 0 0 [2-4] years 95 5 5.26 0.72 – 9.80 > 4 years 110 8 7.27 2.37 – 12.17 sex female 107 7 6.54 1.81 – 11.27 male 113 6 5.31 1.13 – 9.49 body condition poor 55 8 14.54 5.09 – 24.00 medium 120 5 4.17 0.56 – 7.78 good 45 0 0 ci=confidence interval hematological finding: the packed cell volume (pcv) of parasitemic animals falls in the range of 21.0 25.0% while in aparasitemic cattle was in the range of 21.0 37.0%. the mean pcv for the parasitemic animals was 23.76%, whereas 28.27% for the aparasitemic animals. moreover, the difference in the mean pcv of the parasitemic and aparasitemic groups was statistically significant (p<0.05) (table 7). 29 east afr. j. biophys. comput. sci., vol. 1, no. 1 table -7. the packed cell volume of parasitemic and aparasitemic cattle in the study area status no. examined mean pcv(%) std. err. std. dev. 95% conf. interval] ttest p-value aparasitemic 207 28.271 0.245 3.52 27.78 28.75 4.575 0.0000 parasitemic 13 23.770 0.395 1.42 22.91 24.63 total 220 28.005 0.242 3.59 27.53 28.48 discussion the results of the focus group discussion revealed that trypanosomiasis, locally called as ‘shulula’, was reported to be the most important livestock constraint limiting the overall agricultural activity and livestock productivity in the study area. similar result was also reported by afewerk (1998) and tewelde (2001) in the western and northwestern parts of ethiopia where cyclically (tsetse) transmitted trypanosomiasis is the primary problem for livestock productivity and agricultural development. although trypanosomiasis occur throughout the year, major infections are observed in boniya (bega) (39.6%), badheessa (belg) (33.7%) and silla (summar) (26.7%) based on the local calendar afewerk (1998) and tewelde (2001) reported consistent results. according to the result of focus group discussion, the occurrence of trypanosomiasis is higher in the adult (61%) followed by young (29%) and in calves (10%). this might be due to the management system in the area that the adult and young animals stay around omo river basin for grazing where there were tsetse fly population exists, while the calves are confined at home and not exposed for tsetse. also the discussion revealed that, trypanosomiasis control and prevention methods depends as much as 62% in the use of different trypanocidal drugs and the rest 38% relay on spraying of insecticides. the overall prevalence of bovine trypanosomiasis recorded in the current study (5.91%) was much lower than the previous findings. different researchers reported different prevalence in different parts of ethiopia. abraham and tesfaheywot, 2012; ataro et al., 2015; tamirat et al., 2016; dejen, 2017; shimels and bosona, 2017; megersa et al., 2019 who reported 27.5%, 21.33%, 26.82%, 26.3%, 21.5% and 12.24% in wozeka grid on the southern part of arbaminch, konta special woreda, southern ethiopia, loma woreda, dawuro zone, southern ethiopia, nyangatom woreda of south omo, snnprs, ethiopia, botor tolay district, bombasi woreda, western ethiopia and jimma zone, respectively. this might be due to the difference in using control methods of trypanosomiasis, climate and ecological conditions such as altitude, rainfall, and temperature and livestock management system. this is comparable with the previous studies of 6.3% (adale and yasin, 2013) in wolaita zone kindokoysha district of ethiopia and 8.3% (eshetu et al,. 2017) in mareka district of dawuro zone, southern ethiopia. the lower prevalence of bovine trypanosomiasis in the current study area might be due to periodical measures taken by the government to 30 east afr. j. biophys. comput. sci., vol. 1, no. 1 control tsetse population from the area. this may be due to increased and frequent use of different trypanocidal drug and easy accessibility of trypanocidal drugs, even there is home to home treatment service. various studies reported the most prevalent trypanosome species in tsetse infested areas of ethiopia were t. congolense and t. vivax sometimes t. brucei and mixed infection in some extent (fikru et al., 2012; leta et al., 2016). the finding of this study revealed that the majority of the infection was due to t. congolense (61.57%), t. vivax (30.76%) and the least was infection by mixed infection (t. congolense and t. vivax) (7.69%). the higher infection rate of t. congolense in the study area was in agreement with trypanosome species prevalence data from other tsetse infested region of ethiopia. abraham and tesfaheywot, (2012); adale and yasin, 2013 and megersa et al., 2019 reported t. congolense 61.4%, 58.8% and 59.6% in wozeka grid on the southern part of arbaminch, wolaita zone kindo koysha district of ethiopia and botor tolay district, jimma zone ethiopia respectively. this study revealed the infection rate of t. vivaxis 14.2%, 29.4% and 25.5% respectively. the species specific trypanosomiasis prevalence rate in bombasi woreda, western ethiopia was; trypanosome congolense 51.76%, trypanosome vivax 28.23%, trypanosome brucei 11.76% and mixed 8.23% (shimels and bosona, 2017). in the present study, t. congolense was the predominant species in the study area which may be due to the development of better immune response to t. vivax by the infected animal (leak et al., 1999). however, it was statistically insignificant in the study area (p>0.05). vector born trypanosome species are disseminated in most parts of western and south western parts of ethiopia (roeder et al. 1984). the infection rate of female is higher than male cattle in the present study but there was no statistical difference (p=0.698). this result is comparable with the findings of dejen, (2017) and megersa et al., (2019). the present study is in agreement with the previous reports of konta special woreda; which was 20.7% in female and 17.3% in male cattle which shows no significant statistical variation (migbaru and desta, 2015). similar findings were also reported by daya and abebe (2008) and tadesse and tsegaye (2010). this may be due to the physiological difference between sex groups. the possible explanation for higher prevalence of trypanosomes in female animals in the present study area might be the fact that female animals were more likely exposed to tsetse flies as they were always released to common grazing sites of tsetse infestation, in contrast to male animals as they were kept in the house after ploughing and have little chance to be exposed to tsetse flies (eshetu et al,. 2017). the prevalence of trypanosomiasis on different age groups was 0%, 5.26% and 7.27% in young (<2 years), medium (2≤x≤4) and adult (>4), respectively. the difference in prevalence among the different age groups was not statistically significant (p>0.05). this might be due to the less exposure of calves for the tsetse flies, since most of them were confined at homes whereas as the young and the adults move far distance in search of feed and water. such areas are widely known for their high tsetse population thereby this may increase their probability to contract with the agent (adale and yasin, 2013). 31 east afr. j. biophys. comput. sci., vol. 1, no. 1 the higher prevalence of trypanosomiasis in cattle with poor body conditioned than in medium and good body conditioned animals in the study area was recorded and it was comparable with the results of abraham and tesfaheywot et al. (2012) in arbaminch area and, adale and yasin (2013) in wolaita zone kindo koysha district, southern ethiopia. this might be due to the fact that poor body condition animals are susceptible to the infectious disease and reduced performance of the animals may be created by lack of essential nutrients and poor management by the animal owner. regarding the pcv determination, the mean pcv of the parasitemic animals (23.76%) was lower compared to aparasitemic animals (28.27%) and the difference was significant (p<0.05). likewise, van den boossche and rowlands (2001) stated that the average pcv of parasitologically negative animals was significantly higher than that of parasitologically positive animals. conclusion & recommendations based on focus group discussion bovine trypanosomiasis is the major constraint for the livestock production in the area. the current study also revealed an overall prevalence of 5.91% for bovine trypanosomiasis based ob buffy coat examination. the predominant trypanosome species found were t. congolense and t. vivax. the mean pcv values indicated the trypanosome infection has been found to cause anemia in cattle. according to the community, bovine trypanosomiasis is the major problem than other livestock diseases in the area. to reduce the prevalence of the disease in the area, appropriate tsetse and trypanosomiasis control action should be integrated and strengthened. moreover, further studies on the tsetse challenge and the economic impact of trypanosomiasis on the agricultural productivity should be conducted acknowledgements the cooperation of bale veterinary clinic and wolaita sodo veterinary regional laboratory is acknowledged for their contribution to the successes of this work. references abebe g. 2005. current situation of trypanosomiasis in ethiopia. review article trypanosomiasis in ethiopia. ethiop. j. biol. sci. 4 (1)፡ 75-121. abraham z. and tesfaheywot z. 2012.prevalence of bovine trypanosomiasis in selected district of arba 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zone, south western ethiopia. trop. anim. health prod. 42(2) : 1757-1762. 33 https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-016-1404-x#auth-melkamu-bezie https://doi.org/10.1186/s13071-016-1404-x http://dx.doi.org/10.19080/ijcsmb.2018.04.555649 east afr. j. biophys. comput. sci., vol. 1, no. 1 tamirat t., tsegabrihan k. and andualem t. 2016. prevalence and control approaches used in tsetse and trypanosomiasis of bovine at loma woreda, dawuro zone, southern ethiopia. europ. j. biol. sci. 8 (1) : 01-07. tesfaye m. 2002. report of trypanosome infection rate in g. m. morstans and g. tachninoides in didessa valley from july 29 to september, 26/2002. bedelle. tewelde t. 2001. study on the occurrence of drug resistant trypanosomes in cattle in the farming in tsetse control areas (fitca) project in western ethiopia. addis ababa university, faculty of veterinary medicine, ethiopia, msc thesis. thrusfield m. 2005.veterinary epidemiology 3rd ed. black well science ltd. uk, edinbergh. pp 228-246. urquhart g., armour j. and duncan j. 1996.veterinary parasitology. 2ndedn, oxford, uk: blackwell science.212‒230. van den boossche p. and rowlands g. 2001. the relationship between the parasitological prevalence of trypanosome infection in cattle and herd average packed cell volume. acta trop. 78: 163-170. 34 cover v1.pdf (p.1) slide number 1 blank page.pdf (p.2) table of contents vol1.pdf (p.3-5) guideline to authors_ eajbcs.pdf (p.6-14) back cover.pdf (p.15) editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction east afr. j. biophys. comput. sci. (2022), vol. 3, issue. 1, 17-22 *corresponding author: email: addisk2013@gmail.com, +251 909 164446 https://dx.doi.org/10.4314/eajbcs.v3i1.3s infestation of ixodidae ticks in cattle: prevalence and associated risk factors in ambo district, western ethiopia addis kassahun gebremeskel*, berhanu mekibib and bekele dabassa faculty of veterinary medicine, college of natural and computational sciences, hawassa university, p. o. box 05, hawassa, ethiopia keywords: ambo district; cattle; ectoparasites; prevalence; risk factors; ticks abstract in ethiopia, ticks cause serious economic loss particularly in ruminants. a cross sectional study was undertaken in ambo district, western ethiopia from october, 2018 to june, 2019 with the major aim of estimating the prevalence, identifying the associated risk factors and the tick species of cattle in the area. from five purposively selected kebeles (the smallest administrative unit of ethiopia) of the district, a total of 384 cattle were selected by systematic random sampling method. adult ixodid ticks were collected from different body parts of infested cattle, preserved in 10% formalin and transported to ambo university veterinary parasitology laboratory for stereomicroscopic identification to species level. among 384 cattle examined, 201 (52.34%) cattle were infested with one or two tick species. higher prevalence of tick infestation was recorded in degele gatira kebele (53.25%), followed by abebe doyo (50.65%), gosu kora (50.65%), kisose liban (50.65%) and senkele faris (56.59%). the study investigated three genera of ixodid ticks namely rhipicephalus (41.7%), boophilus (0.8%) and amblyomma (2.60%). mixed infestations were common including rh. boophilus and amblyomma 24(6.25%) and rh. boophilus and rhipicephalus 4(1.04%). the study identified four species of ticks; namely rh. (bo.) decoloratus 109 (28.40%), rhipicephalus (boophilus) annulatus 43(11.20%), amblyomma vareigatum 3(0.80%) and rhipicephalus evertsi evertsi 11(2.90%). the difference in tick infestation was statistically insignificant (p >0.05) between different age groups and kebeles but statistically significant (p <0.05) among sex groups, breeds and different body condition scores (p <0.05). in conclusion, this study indicated high prevalence of tick infestation and identified most important ticks that can transmit various livestock diseases. proper tick eradication campaign should be conducted to decrease the tick burden in the study area, and concomitantly reduce tick-borne diseases and associated economic losses. introduction ethiopia has an enormous and diverse livestock population that plays an important role in the economy and livelihoods of farmers and pastoralists (akande et al., 2010). the country has 65 million cattle, 40 million sheep, 51 million goats, 8 million camels and 49 million chickens. from the total cattle population, 97.8%, 1.9% and 0.3% cattle are indigenous, hybrid and exotic, respectively (csa, 2020). east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article mailto:addisk2013@gmail.com https://dx.doi.org/10.4314/eajbcs.v3i1.3s 18 despite the large animal population, their productivity is low due to poor nutrition, reproduction insufficiency, management constraints and prevailing livestock diseases (bekele et al., 2010). parasitic diseases are among the major problems of domestic animals causing serious economic loss (shiferaw, 2018). ectoparasites are organisms which inhibits the skin or outgrowth of the skin of the host for various periods (hopla et al., 1994). in ethiopia, ectoparasites in ruminant causes serious economic losses to small holder farmers, the tanning industry and the country as a whole through mortality, decreased production, downgrading and rejection of skin and hide (peter, 2005). ectoparasites can live permanently on their host, or they may occupy the host’s nest and immediate environment, and visit the body of the host periodically (gross et al., 2005). in either case, there is a close dependency on the host for various life sustaining resources (gonzalez et al., 2004). from the ectoparasites, ticks are ranked as the most economically important arthropods in tropics including subsaharan africa (abdela, 2016). ticks have adverse effect on livestock in several ways and parasitize a wide range of vertebrate hosts and transmit a wide variety of pathogenic agents than any other group of arthropods (oliver, 1989; belew and mekonnen, 2011). ticks transmit protozoa, bacterial, rickettsial and viral diseases. moreover, ticks down grade hide and skins quality and reduce milk and wool production, reduce productivity and increase susceptibility to the other diseases (de castro, 1997). ticks can predispose animals to secondary attacks from other parasites such as screw worm flies and infection by pathogens east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 17-22 such as dermatophilos congolensis, the causative agent of streptothricosis (desta, 2010). there are various cattle tick-borne diseases in ethiopia such as anaplasmosis, babesiosis, theileriosis (mekonnen et al., 1992) and streptothricosis (surafel and amsalu, 2019). despite the known or existing challenges and the prevalence of tick-related problems in ethiopia, there is a clear and notable lack of documented information regarding the specific species and associated risk factors of ticks in cattle within the study area. therefore, the current study was designed and implemented with the objectives of estimating the prevalence of tick infestation, identifying the existing species of ticks and assessing the potential risk factors associated with the occurrence of hard ticks (ixoid) in cattle in ambo district, western ethiopia. materials and methods description of the study area the study was conducted in five kebeles (the smallest administrative unit of ethiopia) of ambo district namely degele gatra, abebe doyo, gosu kora, kisose liben and senkele faris from october, 2018 to june, 2019. ambo district has a total of 35 kebeles. the area is lcated at latitude and lngitude of 8°59'n, 37° 51'e, respectively and an elevation of 2101m above sea level. ambo has livestock populations of 145, 371 cattle, 50,152 sheep, 27, 026 gats, 9, 088 hrses, 2, 914 donkeys and 256 mules. the area is characterized by bi-modal rainfall with mean annual rainfall of 1129mm per year and annual temperature ranging from 10 to 28oc (csa, 2007; firaol et al., 2014) . east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 17-22 19 study design and study population a cross sectional study was conducted on a total of 384 cattle randomly selected from the population. the study populations were includes both local and exotic breeds of cattle with different ages, sex and body condition cores. out of the 35 kebeles found in the district, five kebeles were selected purposively for their accessibility and large cattle population. the age of the cattle was estimated based on the description given by nicholson and butterworth (1996), and then categorized as young (≤1 year), adult (1-3 years) and old (≥ 3 years). similarly, based on their body condition scores, the cattle were classified as good, medium and poor. sample size determination and sampling method the minimum sample size required for this study was determined according to the formula given by thrusfield and brown (2018). accordingly, 95% cnfidence interval, 5% precision and 50% expected prevalence was used as there was no previous study conducted in the area. n = 𝑍2 ∗ 𝑃𝑒𝑥𝑝(1 − 𝑃𝑒𝑥𝑝) 𝑑2 where, n= required sample size, z= confidence interval (95%), pexp= expected prevalence and d = desired absolute precision. therefore, the computed sample size was 384. collection & laboratory examination of ticks animals’ body was visually examined for tick infestation and adult ticks were collected by using universal bottle containing 10% formalin. each sample was correctly labeled (with age, sex, breed, body condition and kebeles) and transported to ambo university veterinary parasitology laboratory for identification to species level by using stereomicroscopic. ticks identification was conducted following previous protocol described by wall and shearer (2001). data analysis data collected from the field and the laboratory were entered in to micrsft excel spread sheet and coded, and then analyzed using spss version 20. descriptive statistics were used to know the prevalence of tick infestation, and association between the tick infestations and host risk factors (sex, age, breed, body condition score and kebeles) was assessed by pearson chi square test. results out of 384 cattle examined, 201 (52.34%) were found infested with one or more ticks’ species. there were statistically significant (p<0.05) association between tick infestation and sex, breeds and body condition scores whereas it was statistically insignificant (p>0.05) with age groups and kebeles (table 1). the study investigated three genera of adult ixodid ticks; namely rhipicephalus (41.7%), boophilus (0.8%), amblyomma (2.60%). mixed infestations were common by rhipicephalus (boophilus) and amblyomma 24(6.25%) and rhipicephalus (boophilus) and rhipicephalus 4(1.04%) (table 2). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 17-22 20 risk factors number examined prevalence n (%) 2 p-value age young (1 year) 66 26(39.40) 1.3 0.515 adult (1-3 year) 195 107(54.90) old (>3 year) 123 63(51.22) sex male 190 83(43.70) 11.3 0.001 female 194 118(60.62) breed local 298 144(48.32) hf 86 57(66.30) 8.6 0.003 bcs good 198 79(39.90) 51.2 0.000 medium 117 60(51.30) poor 69 62(89.60) kebele degele gatra 77 41(53.25) 39(50.65) 39(50.65) 39(50.65) 43(56.60) 0.838 0.933 abebe doyo 77 gosukora 77 kisoseliben 77 senkelefaris 76 genus of ticks prevalence (%) amblyomma 3 (0.80) rhipicephalus (boophilus) 160 (41.70) rhipicephalus 10 (2.60) amblyoma & rhihipicephalus (boophilus) 24 (6.25) rhipicephalus (boophilus) & rhipicephalus 4 (1.04) total 201 (52.4) species rh. (b.) annulatus 43 (11.20) rh. (b.) decoloratus 109 (28.40) a. variegatum 3 (0.80) rh. e. evertsi 11 (2.90) rh. ( b.) annulatus & a. variegatum 3 (0.80) rh. (b.) annulatus & rh.(b.) decolratus 6 (1.60) rh. (b.) decoloratus & rh. e. evertsi 2(0.52) ..rh. (b.) decoloratus & a. variegatum 21(5.50) rh. (b.) annulatus & rh. e. evertsi. 3(0.80) discussion the overall prevalence of tick infestation (52.34%) recorded in the current study is comparable with previous report made by tadele et al. (2018) (51.30%). however, it was far lower than the finding of dabasa et al. (2017) (98.20%) and higher than the report of 33.21% by surafel and amsalu (2019). according to pegram et al. (1981), tick activities and prevalence in a given area are affected by rainfall, temperature, altitude and atmospheric relative humidity and management table 1: relation between tick infestation and risk factors in ambo district, western ethiopia table 2: distribution of tick genera in ambo district, western ethiopia from october 2018 to june 2019 east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 17-22 21 system including the use of accaricide and other preventive measures, agro-climatic condition and other epidemiological factors. cross breed cattle were highly affected by tick infestation compared with local breed cattle. this finding was in line with the result of belay and enyew (2016). however, it disagrees with the report of surafel and amsalu (2019). the higher prevalence of tick infestation in cross and pure exotic breed animals might be attributed to preimmunity against ectoparasites, which often established through contacts with the parasites at the early stage of their life (ahmed et al., 2012). the proportion of infestation was higher in adult and old animals as compared to young animals, which was most likely due to outdoor management and long distant mobilization of adult and old animals in search of feed and water as the result the chance of exposure to tick could be higher than that of younger animals (sutherst and maywald, 1983). in the current study, female cattle were more infested by tick (60.82%) than male cattle (54.90%). this finding was in line with the report of shichibi et al. (2017) in masha district. this could be partly explained by the high chance of physiological stress (pregnancy or lactation) which create favorable conditions to tick infestation and other external parasite infestations (sutherst and maywald, 1983). higher prevalence of tick infestation was recorded in thin cattle compared to medium and good body conditioned animals. this result was comparable with reports of fanos et al. (2012) who conducted similar study in and around mizan teferi, southwestern ethiopia. however, it contradict with a study conducted in gozamin woreda, east gojjam (tadele et al., 2018). animals with poor body condition had reduced resistance to tick infestation, lack of enough body potential to build resistance and they exposed to any kind of diseases when grazing on the field (manan et al., 2007). on the other possible scenario, the poor body condition observed in those cattle with tick infestation could be due to the effect of the parasite on the energy balance of the animal. in this study rh. (b.) decolaratus was most abundant tick species (28.40%). this result was in line with wasihun and doda (2013) who reported a prevalence of 30.63% for this tick from humbo district. in contrast to amante et al. (2014), the current finding was lower. the variations could be due to the difference in the geographic area, climate, altitude and season during tick collection. furthermore, rh. e.evertsi was the third abundant tick species (6.72%) of the total adult tick collected. this result was slightly in line with the report of abebe et al. (2010) who conducted similar study in somali region, ethiopia. conclusion tick infestation is the common problem in the study area that occurs on every other animal. rhipicephalus (boophilus) decoloratus are the leading genus of ticks affecting mainly exotic and cross breed, female cattle with poor body condition of adult to old age in the study area. although, the prevalence of ticks was high in the study area, proper policies and strategies are not yet in place to control ticks and other external parasites. therefore, sustainable tick control program should be introduced in order minimize the prevalence to the lowest level so that tick borne diseases and other tick associated problems can be prevented. acknowledgment the authors would like to thank hawassa university and ambo university for supporting this study. references abdela n. 2016. important cattle ticks and tick born haemoparasitic disease in ethiopia: a review. acta parasitol glob 7(1): 12-20 east afr. j. biophys. comput. sci. 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(ed.), veterinary epidemiology fourth ed. hoboken, nj: wiley. pp 275-277. wall r. and shearer d. 2001. veterinary ectoparasites: biology, pathology and control. blackwell’s science ltd. wasihun p. and doda d. 2013. study on prevalence and identification of ticks in humbo district, southern nations, nationalities, and people's region (snnpr), ethiopia. j. vet. med. anim. health 5(3): 73-80. *corresponding author: email: berhanumm2002@gmail.com, phone +25191 024 8878 study on clinically manifested reproductive health problems of dairy cows managed under intensive and semi-intensive production systems in wondo genet district, southern ethiopia amene fekadu1, yifat denbarga1,tesfaye belay2, desie sheferaw1, fufa abunna3, kebede amenu3, rahmeto abebe1, mesele abera1, berhanu mekibib1* 1hawassa university, faculty of veterinary medicine, p.o.box 05, hawassa, ethiopia 2hawassa university, college forestry and natural resources, wondo genet, ethiopia 3addis ababa university, college of veterinary medicine, p.o.box 34, bishoftu, ethiopia keywords: dairy cows; production constraint; bovine brucellosis; wondo genet abstract reproductive disorders in cows are crucial as reproduction and fertility are the two key pillars of dairy production profitability. the study was conducted to identify and estimate the prevalence of clinically manifested postpartum reproductive disorders, to identify the associated risk factors and to estimate the sero-prevalence of brucellosis in dairy cows kept under intensive and semi-intensive dairy farms in wondo genet district from november 2019 to september 2020. out of the total 205 cows examined, 90 cows (43.90%) had at least one of the reproductive problems identified by either questionnaire interview or regular follow up of individual cows. out of 146 cows retrospectively and 59 cows prospectively assessed for the presence of any reproductive disorder, 62 (42.47%) and 28 (47.46%) cows had at least one reproductive disorders, respectively. retained fetal membrane, abortion, uterine infections, anestrous and repeat breeding are the major reproductive disorders encountered followed by dystocia, milk fever and prolapses of the vagina and/or uterus. among the considered host and management related risk factors, only presence of previous reproductive disorder had statistically significant association with the occurrence of reproductive disorder (p<0.05). this study also demonstrated that none of the serum samples collected from wondo genet and other towns (namely hawassa, wolaita sodo and arsi negelle) and tested using indirect multi-species elisa was positive for bovine brucellosis. further studies, preferably laboratory based, should be conducted to identify the underlined causes of these problems in different parts of the country. meanwhile, awareness should be created to farm owners/attendants to improve their farm management system. introduction dairying is one of the livestock productions practiced almost all over ethiopia, involving a vast number of small, medium, or large-sized, subsistence or market-oriented farms (abera, 2016). the dairy sector is dominated by traditional smallholder farmers who account for about 85% of the population and are responsible for 98% of the milk production (moard, 2007). unfortunately, nearly 90% of the milk produced by the rural household is consumed journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx 14 east african journal of biophysical and computational sciences east afr. j. biophys. comput. sci., vol. 2, issue 1, 14-26 research article mailto:berhanumm2002@gmail.com east afr. j. biophys. comput. sci., vol. 2, issue 1 within the producer households with the proportion marketed being not more than 10% (csa, 2020) owing to the rapidly increasing population size, low productivity of the local breeds (1.32 liter/cow per day), a growing urbanization and the concomitant growing demand for dairy products, the country is already in a very high demand-supply variance (seifu and doluschitz, 2014). to partly fill this gap, the country expends over 10 million usd annually for the import of dairy products from different countries (tegegne et al., 2016). for a sustainable economic growth, however, both the public and private sectors are engaging in urban and peri-urban dairy development (seifu and doluschitz, 2014; edao et al., 2018). despite the progressive growth in the commercial (market oriented) dairy farming in urban and peri-urban settings, the dairy industry is still underutilized and challenged by several factors. in general the development of the dairy sector is hindered by poor management system, shortage of proper nutrition, absence of welldeveloped market infrastructures and widespread infectious and parasitic diseases (moa, 1998). among health related issues, reproductive disorders in cows are crucial as reproduction and fertility are the two key pillars of dairy production profitability (leblanc, 2008). these problems, caused by infectious and non-infectious causes, are responsible to reduce milk yield and subsequent reproductive performance of dairy cows (rajala and gröhn, 1998; leblanc et al., 2002; leblanc, 2008) and ultimately cause premature and forced culling of high producing dairy cows (esslemont and peeler, 1993). bovine brucellosis, a bacterial zoonotic disease, is one of the infectious diseases assumed to hamper productivity of cattle in the country (ibrahim et al., 2010; edao et al., 2018). the disease in cattle is characterized clinically by abortion at third trimester of first gestation, retained fetal membrane (rfm), metritis, orchitis and epididymitis (radostits et al., 2006). bovine brucellosis has been reported from several parts of the country, particularly in cows kept in intensive and extensive management systems. however, recent reports particularly from central and southern ethiopia are revealing a very low to zero prevalence (alem and solomon, 2002; belihu, 2002; asmare et al., 2013; bashitu et al,.2015, edao et al., 2018). although several studies have been conducted on the prevalence of bovine brucellosis (asmare et al., 2013; edao et al., 2018; ataro e al., 2019; dinknesh et al., 2019) and/or on the major reproductive disorders (lobago et al., 2006; hunduma, 2013; wujira and nibret, 2016; yohannes and alemu, 2019), majority are limited in the central highland, dairy farms of research centres and major towns/cities of the country. however, there is still paucity of information in some parts of the country including wondo genet district. moreover, the scope of reproductive health in the dairy industry still demands more intensive investigation for better formulation of prevention strategies. therefore, the present study is intended to identify and estimate the prevalence of the major clinically manifested postpartum reproductive disorders, to identify the associated risk factors and to estimate the sero-prevalence of brucellosis in dairy cows kept under intensive and semi-intensive dairy farms in wondo genet district. 15 east afr. j. biophys. comput. sci., vol. 2, issue 1 materials and methods study area study design study design and sample size both retrospective (questionnaire based) and prospective (follow-up and serological) studies were undertaken from november 2019 to september 2020 to estimate the prevalence of major reproductive problems in dairy cows. all female cattle with at least one calving history were purposively selected for the retrospective survey. for the prospective follow-up study, however, all pregnant cows and heifers (in their first pregnancy) which were at 4th or more months of gestation were selected and registered according to their ear tag numbers /given name for follow-up. study population and study animals 16 the study was conducted in wondo genet district, which is located 24km north east of hawassa, the capital city of sidama regional state and 265.km to south of addis ababa, the capital of the country, ethiopia. the district is classified administratively into 13 rural and 2 urban villages. it has temperature and altitude ranging from 7 to 26 °c and 1761 to 2695 m above sea level, respectively. the average rainfall is 1120 mm per annum and the main rainy season in the area is between july and early october (bolka and gebremedhin, 2019). in the area, animal husbandry is the main subsistent farming where cattle, sheep, goats and equines are the species of animals found (jones et al., 2011). the town is known for its high potential in dairy production in southern ethiopia and major source of milk and other dairy products. the number of cattle required for serological survey was calculated based on the formula described by thrusfield and brown (2018), with 5% absolute precision with 95% confidence level. moreover, a prevalence (2.7%) reported by ataro et al. (2019) from hawassa was used as expected prevalence as there is no previous report from wondo genet and its surroundings. as a result, the sample size computed was 40 for the study area. however, the sample size was increased by 5 fold and hence a total of 200 cows were randomly selected and examined. moreover, equal numbers of animals were also sampled from the different farms found in hawassa, arsi negelle and wolaita sodo for serological survey. the study population constituted all the dairy cows found in wondo genet district. the majority of dairy producers included in this study were market oriented small holder dairy farmers with average herd size of 10 cows. although majority of the farms are small scale, there are also few governmental and private owned large (commercial) scale dairy farms with heard size of over 50. most of these farms rear crossbred dairy cattle under semi-intensive management system. hay and concentrate (wheat bran, molasses and oil and brewery byproducts) were the common types of feed used in almost all farms. majority of the management activities including heat detection (detection for the major oestrus sign of the cows) were done by the owners and attendants of the farm. although both artificial insemination (ai) and natural method of breeding system were practiced in the study areas, most of the owners prefer natural mating because their cows repeat more than two times when inseminated by ai. https://www.ncbi.nlm.nih.gov/pubmed/?term=bolka%20a%5bauthor%5d&cauthor=true&cauthor_uid=31146689 https://www.ncbi.nlm.nih.gov/pubmed/?term=gebremedhin%20s%5bauthor%5d&cauthor=true&cauthor_uid=31146689 east afr. j. biophys. comput. sci., vol. 2, issue 1 in all the farms, there was no regular vaccination and deworming practices for the common infectious and parasitic diseases, respectively. study methodology this research employed both retrospective and prospective (i.e. follow-up) studies to generate relevant data to attain the aforementioned specific objectives. moreover, serological survey was also conducted to estimate the prevalence of bovine brucellosis. retrospective survey retrospective data was collected from the cow level record books kept by the farms (if any) and by using pretested semi-structured questionnaire (administered in the form of interview). before the commencement of the interview, of course to get full co-operation of the dairy owners and hence obtain reliable data about their animals, thorough explanation was made to the respondent on the objectives of the study before the start of the interview and record exploration. during the interview, the actual questions on questionnaire were systematically and chronologically presented in amharic (the national language). accordingly, herd level information (housing, feeding, source of feed, herd size) and cow level information (parity, breed, service used, source of the cow, number of service per conception, and history of any reproductive disorder on the previous calving) were collected and recorded. all the cow level information was registered by their ear tag number and/ or given name for ease of identification. moreover, the data collectors tried to make personal judgment and validation on the information given pertaining the management and husbandry. to avoid ambiguity, the major reproductive problems (namely abortion, dystocia, retained fetal membrane (rfm), uterine infection, anoestrous, repeat breeder, vaginal prolapse and uterine prolapsed) were clearly defined according to the literature and explained to respondents. follow-up survey during postpartum period, cows were regularly examined for the presence of retained fetal membrane, any systemic signs, and abnormal vaginal discharge. during each visit, rectal temperature of cows with rough hair coat, depression and reduced appetite was measured by digital veterinary thermometers (microlife vt1831; measurement accuracy of ± 0.1°c). each postpartum cow was visually inspected for the presence of any discharge on the vulva, perineum or tail. moreover, after cleaning the vulva, a clean and sterile vaginal speculum was slowly inserted into the vagina of the cows and then the cervix and vagina were thoroughly inspected with illumination from a penlight. the type and nature of the vaginal discharge was differentiated from cows with normal delivery. the nature of discharge was classified as clear mucus, predominantly clear mucus with flecks of pus, mucopurulent (approximately 50% pus and 50% mucus), purulent (>50% pus) but not foul-smelling, or purulent or red-brown and foul smelling according to leblanc et al. (2002). retained fetal membrane was defined as failure to pass the fetal membrane within 24 h postpartum (kelton et al., 1998). abortion was defined as the expulsion of a dead fetus of recognizable size at any stage of gestation (robert, 1986; ball and peters, 2004). anoestrus was defined as the failure of the cow to show clinical heat signs for 90 days or more 17 east afr. j. biophys. comput. sci., vol. 2, issue 1 after parturition (arthur et al., 1992; bekana et al., 1994). moreover, cows or heifers that cycle normally and have on clinical abnormality but failed to conceive by three or more consecutive services were considered as repeat breeder (robert, 1986; bonneville-hébert et al., 2011). serological survey blood and serum sample collection approximately 10ml of blood samples were collected from the jugular vein of the randomly selected cows (800 in total) using plain vacationer tubes. each tube was properly labelled with codes and allowed to clot over overnight at room temperature by placing inclined on a table. on the next morning, the sera were separated undisturbed, aliquated in to 1.8 ml cryo vials, properly labelled, transported and stored at -20⁰c in fvm-hu lab. the sera were shipped with a cold chain to the national animal health diagnostic and investigation centre nahdic), sebeta, for a better and safe storage and serological tests. during sample collection, the town, farm name, herd size, cow id / name, parity, breed, history of previous abortion/reproductive disorder and current physiological state (viz lactating, dry, pregnant) were recorded for all sampled animals on a format prepared for the same. serological examination in the lab, the sera were exposed for brucellosis serological tests (id screen  brucellosis serum indirect multi-species elisa) as per the kits’ instruction (id.vet innovative diagnostic, rue louis pasturegrables, france). briefly, before performing the test, the sera and all reagents taken out of the refrigerator and left at room temperature for half an hour and homogenized by inversion and flicking with finger. the serum and controls (positive and negative controls), at a dilution rate of 1/20 were added to microwells coated with brucella abortus lps. the plates were incubated at 37°c in a humid incubator for 60 min and washed 3x with washing buffer. then, 100 μl of the conjugate was added to each well and incubated again at 37°c and wet for 60 min. again, washes were repeated, and 100 μl of tbm (substrate solution) were added, the wells were shaken, covered, and incubated at 18-26°c for 15 min. finally, the reaction was stopped by adding 100 μl of the “stop” solution to each well and the results were read using an automated elisa reader with a wavelength of 450 nm. the test were valid if the mean od value of positive and ratio of positive to negative controls were calculated as odpc > 0.350 and odpc/odnc > 3, respectively. the result was interpreted by sero-positivity percentage (s/p %) of ≥120% as positive and ≤ 110% as negative. data management and analysis 18 the data obtained from questionnaire and follow-up surveys were carefully entered into farm and cow-level database excel files. the data were coded and analyzed using stata 14.2 window version (statacorp, college station, tx usa). the association of different risk-factors such as breed, management system, and methods of breeding with over all prevalence of reproductive problems were analysed by using χ2 (chisquare) test and value of p<0.05 considered as significant. east afr. j. biophys. comput. sci., vol. 2, issue 1 results in general, out of the total 205 cows examined, 90 cows (43.90%) were having at least one of the reproductive disorders identified by either questionnaire interview or regular follow up of individual cows. out of 146 cows retrospectively and 59 cows prospectively assessed for the presence of any reproductive disorder, 62 (42.47%) and 28 (47.46%) cows had at least one reproductive disorders, respectively. based on questionnaire surrey and longitudinal study (follow-up), retained fetal membrane, abortion, uterine infection, anestrus, repeat breeding, dystocia, hypocalcemia, uterine prolapsed and vaginal prolapsed were the major reproductive problems in dairy cows of wondo genet district (table 1). on questionnaire survey, retained fetal membrane and abortion (12.33% each), anestrus (8.22%), and dystocia (4.79%) were the leading reproductive problems in dairy farms. whereas, uterine infection (23.73%), retained fetal membrane (18.64%), and repeat breeding (15.25%) were the leading problems encountered during the follow-up period (table 1). table-1: table 1: major reproductive disorders of cows encountered in the study area type of reproductive disorder follow-up (n=59) retrospective (n=146) overall (n=205) no (%) affected no (%) affected no (%) affected retained fetal membrane 11 (18.64) 18 (12.33) 29 (14.15) dystocia 3 (5.08) 7 (4.79) 10 (4.88) uterine infection 14 (23.73) 6 (4.11) 20 (9.76) abortion 6 (10.17) 18 (12.33) 24 (11.71) hypocalcaemia 3 (5.08) 4 (2.74) 7 (3.41) anestrous 5 (8.47) 12 (8.22) 17 (8.29) uterine prolapsed 2 (1.37) 1 (1.69) 3 (1.46) repeat breeder 9 (15.25) 3 (2.05) 12 (5.85) vaginal prolapse 1 (1.69) 2 (1.37) 3 (1.46) overall (at least one reproductive disorder) 28 (47.46) 62 (42.47) 90 (43.90) although reproductive disorder is multifactorial in nature and influenced by several host and environment (management) related factors, only the most important and widely accepted factors are considered in this study. among the considered host related risk factors, only the presence of previous reproductive disorder had statistically significant association with the occurrence of reproductive disorder (p<0.05) (table 2). 19 east afr. j. biophys. comput. sci., vol. 2, issue 1 table2. host factors associated with the occurrence of major reproductive problems factors no cows examined cows affected, no (%) χ2 p value body condition score poor 6 5 (83.3) 3.455 0.175 medium 28 12 (42.86) good 25 11 (44) previous rep. performance poor 21 15 (71.43) 7.514 0.006 good 38 13 (34.21) nsc one 33 15 (45.45) 0.12 0.73 ≥two 26 13 (50) parity first 6 3 (50) 2.752 0.432 second 14 4 (28.57) third 14 8 (57.14) ≥fourth 25 13 (52) breed/blood level 50%hf* 21 10 (47.62) 0.850 0.654 75%hf 14 8 (57.14) 87.5%hf 24 10 (41.67) nsc=number of service per conception, hf=holstein friesian on the other hand, among the considered management related risk factors (vis-a-viz source of the animal, management type, service used, floor type, presence of calving pen and contact with dogs) none of them had statistically significant association with the occurrence of reproductive disorders (table 3). table -3. management factors associated with the occurrence of major reproductive problems factors no cows examined cows affected, no (%) χ2 p value source of the animal raised in the farm 36 17 (47.2) 0.002 0.964 purchased 23 11 (47.83) management semiintensive 41 18 (43.9) 0.68 0.41 intensive 18 10 (55.6) contact with dogs yes 38 17 (44.7) 0.317 0.573 no 21 11 (52.4) floor type soil 13 9 (69.2) 3.17 0.075 concrete 46 19 (41.3) graze outside yes 33 13 (39.4) 1.95 0.162 no 26 15 (57.7) calving pen yes 31 12 (38.7) 2.005 0.157 no 28 16 (57.1) service used natural 40 9 (47.5) 0.0001 0.992 ai 19 9 (47.37) 20 east afr. j. biophys. comput. sci., vol. 2, issue 1 among the different reproductive disorders, abortion and retained fetal membrane showed statistically significant association (p<0.05) with uterine infection that was expressed either in the form of endometritis or metritis (table 4). table-4. association of uterine infection with the other reproductive disorders of cows as a predisposing factor predisposing factors number of cows cows with uterine infection cows without uterine infection χ2 pvalue rfm 11 7(63.6%) 4(36.4%) 11.9 0.001 abortion 6 5(83.3%) 1(16.7%) 13.11 0.000 dystocia 3 1(33.3%) 2(66.7%) 0.16 0.688 hypocalcemia 3 1(33.3%) 2(66.7%) 0.16 0.688 rfm=retained fetal membrane the study further revealed that all the serum samples (800) collected from wondo genet, hawassa, wolaita sodo and arsi negelle were negative for bovine brucellosis. discussion the prevalence of reproductive disorder recorded by the retrospective study (42.47%) is comparable with the studies of dawit and ahmed (2013) and hadush et al (2013), who reported 40.3% and 44.3% from kombolcha and central ethiopia, respectively. based on the existing published literatures, the prevalence of reproductive disorders in dairy cows, as reported by different researchers from different geographic locations in ethiopia, range from 8.99% to 67.8% (shiferaw et al., 2005; abreham et al., 2010; molalegne and shiv, 2011; ayele et al., 2013; hunduma, 2013; ambaw et al., 2017; abunna et al., 2018; abdeta and hailu, 2020). however, the current report and of course most of the reports made earlier in the country, are quite higher than the reports made from abroad (maruf et al., 2012; elhassen et al., 2015; khan et al., 2016). this variation in prevalence might be due to the difference in sample size, study methodology, farm management, environmental factors and breed of the animals kept in the different farms. however, variation in management system that is applied in different dairy farms including provision of veterinary service, proper feed and feeding, housing, hygiene, timely heat detection and insemination, implementation of farm biosecurity measures and record keeping. among the observed reproductive disorders, retained fetal membrane (rfm) was the leading problem accounted for a prevalence of 14.15%. similar findings have been reported elsewhere by abreham et al. (2010) from addis ababa milk shed, ahmed and naod (2019) from jimma town and ayele et al. (2013) from wolaita sodo town. although rfm occurs more frequently in dairy farms of the developing countries, it is still an economically important disease of us dairy industry and affects approximately 7.8% (range: 1.3 to 39.2%) of the dairy cows (usda, 2009; qu et al., 2014). the presence of rfm greatly increases the risk of metritis and endometritis (leblanc, 2008) because of tissue decomposition, compromised immunity and 21 east afr. j. biophys. comput. sci., vol. 2, issue 1 patent cervical canal with a concomitant ascending infection. in line with this, the current study also showed that cows with rfm developed uterine infection more significantly than those without rfm. studies suggest that although the causes of abortion are both infectious and non-infectious in origin, in most cases where a diagnosis is reached, the cause is infectious (cabell, 2007). the attempt made in the current study to estimate the prevalence of bovine brucellosis in 4 selected towns including wondo genet revealed that brucellosis is not prevalent in the area and hence could not be blamed for abortion cases at least in the study areas. the current finding is concordant with the previous studies conducted by belihu (2002) and asmare et al (2013) who couldn’t find positive reactors in dairy farms of the addis ababa area and from central ethiopia (adama) and northern ethiopia (mekele and gondar), respectively. these findings strongly suggest the presence of infectious and/or noninfectious causes other than bovine brucellosis that should be considered the moment other similar serological surveys are planned in the future. 22 uterine infection, in the form of clinical endometritis / metritis, was the third commonly encountered reproductive disorder in the area (9.76%). this problem is also reported by other researchers from different parts of the country with prevalence ranging from 1.2% in bedelle (esheti and moges, 2014) to 16.9% in ada’a district (molalegne and shiv, 2011). according to lewis (1997), as large as 40% of the postpartum cows in some herds abroad may be diagnosed with, and treated for, uterine infections. variation among studies in the prevalence of uterine infection could be emanated from the difference in the diagnostic methods used, the classification of the uterine infections, the postpartum period during which the infections were detected, the parity of the cows, the general characteristics of the cows, or the herd management practices at large. although the risk factors for uterine infections are well established (leblanc et al., 2002), prevention of uterine infections is usually difficult because of the presence of nonspecific bacteria on the lower genitalia and all over the cow’s environment (lewis, 1997). however, most researchers argue that attention to sanitation and periparturent hygiene, particularly during calving, may be the best and wise attempt abortion, the second most frequently encountered reproductive disorder in the current study (11.7%), was also reported as the second leading reproductive disorder in most parts of the country (molalegne and shiv, 2011; abunna et al., 2018; abdeta and hailu, 2020 ). based on the retrospective and/or follow-up studies conducted earlier, the prevalence of abortion in dairy cows in ethiopia ranges from 0.63% in wolaita sodo (ayele et al., 2013) to 28.9% in adea berga dairy farm, west shewa (siyoum et al., 2016). such variation in the prevalence of abortion among these studies could be partly explained by the difference in host and management related risk factors and the presence of different etiological factors for the occurrence of abortion. regardless of the cause, most cases of abortions in cows are followed by uterine infection and hence connected with delayed uterine involution in the postpartum period (getnet et al., 2018). the current study also showed that over 80% of the cows with abortion later developed uterine infection. east afr. j. biophys. comput. sci., vol. 2, issue 1 the effort made to assess the association of different host and management related risk factors with the occurrence of the reproductive disorders revealed that only previous history of reproductive performance showed statistically significant association (p<0.05). this clearly showed that cows with poor reproductive performance in their previous reproductive cycle are more likely to develop at least one of the reproductive disorders in their subsequent pregnancies. this could be partly explained by the likelihood of development of permanent changes (functional and/or mechanical damages like scaring and stenosis) on the uterus and ovaries following most reproductive disorders (bonneville-hébert et al., 2011). the absence of association with the other considered risk factors need to be proved further with a larger sample size preferably on a wider geographic area. conclusion this study revealed the presence of a serious reproductive disorders in cows of the study areas, retained fetal membrane, abortion, uterine infection and anestrus were the leading reproductive disorders followed by others. among the considered host and management related risk factors, only the presence of previous reproductive disorder had statistically significant association with the occurrence of the problem. the serological survey demonstrate that brucellosis was not a problem in area including hawassa, wolaita sodo and arsi negelle towns. since the causes of reproductive disorders are multifactorial, laboratory based studies should be conducted to identify the underlined causes of these problems in different parts of the country. meanwhile, awareness creation to farm owners/attendants to improve their farm management system through proper housing and feeding, accurate and timely heat detection and insemination, regular consultation with animal health and production professionals, selection of feasible breeding method, maintaining hygiene of the cow and its environment and strict farm 23 anoestrus (8.3%) and repeat breeding (5.85%) were the other reproductive disorders encountered in the study area quite frequently. unlike the current findings, these reproductive disorders, particularly anoestrus, are the leading problem in most parts of the country including borena zone (benti and zewdie, 2014), desie and kombolcha (ambaw et al., 2017), hosanna town (adane et al., 2014), nekemte town (abdeta and hailu, 2020), ada’a district (esheti and moges, 2014) and dawro zone (bizuayehu and wale, 2016). some studies from abroad including khan et al. (2016) from india, elhassan et al. (2015) from sudan and maruf et al. (2012) from bangladish also indicated that these problems are the leading among other reproductive disorders. although the causes and pathogenesis of anoestrus and repeat breeding are multifactorial and beyond the scope of this research article to discuss, both problems can partly be the aftermath of other interrelated reproductive disorders mainly dystocia, abortion, retained fetal membrane and uterine infections. most of the owners mentioned that anoestrus and repeat breeding are the major reason for the culling of cows followed by lack of space and feed. in line with this, agarwal et al. (2005) and hadley et al. (2006) also conclude that failure to resume to cyclicity and timely conceive are the major reasons for economic losses and why cows are culled in most dairy farms of the globe. east afr. j. biophys. comput. sci., vol. 2, issue 1 biosecurity can significantly minimize the occurrence of these problems and associated economic losses in the dairy farms of the area. acknowledgment we are grateful to all technical assistants in the bacterial serology laboratory of the national animal health diagnostic and investigation center (nahdic), for their support during serological test. we also thank all owners or managers of the dairy farms included in the study for their permission and collaboration during the study period. references abdeta a. and hailu s. 2020. major reproductive health problems of dairy cows and associated risk factors under small scale and medium scale dairy farms in nekemte town, western ethiopia. j. vet. med. res. 7(5): 1201. abera b. 2016. challenges and opportunities of 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phone +91 8921865558 department of aquatic biology and fisheries, university of kerala, thiruvananthapuram 695581, kerala, india keywords: climate change; fisheries; unfcc; drivers; hydrology; livelihood abstract freshwater ecosystems are vital for ensuring drinking water supplies, bio-resources that support livelihood, and a wide array of ecosystem services. further, they are among the key components in achieving the united nations sustainable development goals (un sdgs) set for the year 2030, including poverty reduction, food security, clean water and sanitation, conservation of biodiversity and climate action. the aquatic ecosystems globally are susceptible to the impacts of climate change much more than terrestrial and marine ecosystems, impacting the livelihood of fishers and farmers depending on it. climate change is expected to adversely affect the sustainable development capabilities of many asian and african nations by putting more pressures on natural resources and the environment. this article reviews the impact of climate change on freshwater ecosystems and fisheries and addresses the key adaptation, mitigation and management strategies to address the issue of climate change. introduction water is inextricably linked to the development of all societies and cultures and is an integral component in all the major pillars of sustainable development including economic, social and environmental. moreover, healthy freshwater ecosystems provide both direct and indirect services to mankind and serve as key components in achieving the united nations sustainable development goals (sdg) set for the year 2030. unsustainable development pathways and anthropogenic interventions such as population growth, urbanization, changing patterns of consumption and climate change have affected the quality and quantity of water availability across the globe, despite the increasing demands for freshwater and the resources therein (wwap, 2015). one of the requirements for sustainable development of water resources is to balance the gap between demand and supply, both in terms of quality and quantity. however, climate east afr. j. biophys. comput. sci., vol. 1, issue. 1 hawassa university college of natural & computational sciences year 2021 volume xx no xx 35 climate change, freshwater ecosystems and inland fisheries: implications for the developing nations biju kumar, a. east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs research article mailto:bijupuzhayoram@gmail.com east afr. j. biophys. comput. sci., vol. 1, no. 1 change may affect both sides of the balance, thereby add to the challenges (ipcc, 2014). global warming and the resultant climate change is occurring at an unrivalled pace in human history (barros et al., 2014), showing progressive threat to freshwater ecosystems (o’gorman et al., 2014; li et al., 2016). under current climate projections, most freshwater ecosystems will face ecologically significant climate change impacts by the middle of this century (ipcc, 2014). most freshwater ecosystems have already begun to feel these effects. these impacts will be largely detrimental to the existing freshwater species and human livelihoods. the impact of climate change may vary in different types of aquatic ecosystems, and also within the same ecosystem such as a river and many impacts remains to be documented in many countries of asia and africa. considering the world’s weather-and climaterelated disasters, asia has encountered the maximum, resulting in colossal economic loss (ipcc, 2012). freshwater species populations have declined on an average by 50 per cent, when compared to 30 per cent for marine and terrestrial species between 1970 and 2000 (mea, 2005). climate change is expected to adversely affect the sustainable development capabilities of most asian and african countries by aggravating pressures on natural resources and the environment. owing to the thick population and considerable economic dependence on inland fisheries in asia, freshwater resources need to be carefully assessed and monitored across the wide range of climates (pfister et al., 2009). according to the report of the inter governmental panel on climate change (ipcc), global warming will lead to “changes in all components of the freshwater system”. water and its availability and quality will be the main pressures on, and issues for, societies and the environment under climate change (bates et al., 2008). according to sharma et al. (2015), during 2014-2015 the food production in india declined substantially due to droughts, flood, hailstorms and unseasonal rains. climate change is expected to adversely affect the sustainable development capabilities of many nations by putting more pressures on natural resources and the environment. india stands second in contributing to the global inland fish production and therefore any impacts of climate change on aquatic ecosystems as well as fisheries should be given due recognition. blessed with diversified agro-climatic conditions, kerala state of india is rich in aquatic resources. it has 44 rivers and their numerous tributaries, canals, lakes, ponds etc. which have the potential to emerge and develop and also to contribute to the livelihood and nutritional support to the country. the rivers in kerala entirely monsoon-fed, some of them nearly turn into rivulets in summer. the state is a part of western ghats sri lanka biodiversity hot spot with greater endemism of freshwater fauna. around 130 species of freshwaterdependent fauna belonging to five taxonomic groups (fish, amphibians, crabs, shrimps and odonates) are endemic to the region, of which 25 per cent have a high risk of extinction (raghavan et al., 2016). even though the wetlands in dry environments are considered productive, the biodiversity hotspots areas, their flora and fauna are under threat of extinction as the runoff decreases and wetland dries out (zacharias and zamparas, 2010). 36 east afr. j. biophys. comput. sci., vol. 1, no. 1 even a very small increase in precipitation will have pronounced effects on freshwater ecosystem. the part of konkan coast and south kerala are considered as the most vulnerable stretches by india’s second national communication to united nations framework convention on climate change (unfccc) (anonymous, 2012). the natural resources from lakes, rivers, ponds, wetlands, reservoirs and backwaters of kerala are depleting due to habitat modification and alterations, pollution, eutrophication, invasive species and climate change. these negative effects definitely have adverse impact on the ecosystem. being a small coastal state located in the tropical region; the climate of kerala is not exposed to severe fluctuation in terms of most of the meteorological factors except rainfall (niyas et al., 2017). the rainfall data from the meteorological department also stipulate the declining pattern of northwest and southeast monsoon especially in the hilly areas of south kerala during the last 60 years. the state receives adequate rainfall (average 3000mm), most of it is obtained via southwest and northeast monsoons. kerala is advancing towards water crisis owing to the variability in temporal and spatial distribution of rainfall and the steep slope of the state allows almost 75% of rainwater to flow to sea at a much faster rate before exploitation (nair, 2016). most of the species adapt to environmental changes but even then it leads to local or global extinctions and biodiversity loss (gallo et al., 2017). unlike marine ecosystem, inland bodies are markedly vulnerable to the climate change. rise in water surface temperature, changes in primary production and changes in fish stock distribution disrupts habitat destruction, aquatic flora and fauna and prey predator composition which will have a nugatory influence on the resources leading to depletion of fish stock and will definitely jeopardise the livelihood of fishers. all these points towards the need for better policies and framework for dealing matters related to the impacts climate change on aquatic ecosystems and inland fisheries. drivers of change the freshwater ecosystems are affected by several stressors, of which climate change is by far more critical (garner et al., 2017). climatic drivers are the temperature, precipitation, evaporation, sea level, carbon dioxide concentration etc. whereas economic developments, urbanization, increase in population and land use or natural geomorphic changes form the non-climatic drivers. of these, the main climatic driver which control freshwater resources are the evaporation and precipitation. more intense extreme precipitation events are expected due to climate change (ipcc, 2012). such drivers question the sustainability of resources by decreasing water supply or increasing demand (cisneros et al., 2014). the future of freshwater systems will be hit strongly by demographic, socioeconomic, and technological changes, including lifestyle changes. the details of framework and linkages for considering impacts of climatic and social changes on freshwater systems, and consequent impacts on and risks for humans and freshwater ecosystems are provided in figure 1. 37 east afr. j. biophys. comput. sci., vol. 1, no. 1 figure 1. framework (boxes) and linkages (arrows) for considering impacts of climatic and social changes on freshwater systems, and consequent impacts on and risks for humans and freshwater ecosystems (source: ipcc report, 2007) according to vanvuuren et al. (2012) socioeconomic features which include the social, economic, demographic as well as ecological conditions can also create climate changes. changing land use pattern because of urbanization will also affect freshwater systems strongly. ninety percent of global water is used for irrigation purpose which will make a severe impact on the freshwater availability to the humans and the ecosystems (döll, 2009). complicated anthropogenic and natural systems working simultaneously influence climate change which affects the quality of water. water quality projections depends upon climatic and environmental inference, local conditions and also the current state of pollution (bonte and zwolsman, 2010; kundzewicz and krysanova, 2010; sahoo et al., 2010; trolle et al., 2011). intense effect of climate change includes alteration on hydrological cycle, dried up water resources and thereby its depletion, decline of water table level, saline water intrusion, water logging etc. which causes strain on the availability of drinking water and altered precipitation and unpredictable floods and droughts on inland freshwater wetlands. the seasonal rainfall in india can be understood from groundwater recharge and the availability of water during summer. because of increase in population and climate change, per capita availability of freshwater in major river basins is decreasing and degrading at a much faster pace 38 east afr. j. biophys. comput. sci., vol. 1, no. 1 and this will be experienced as water stress in most of the basins by 2030 (nair, 2016). this will be followed by many serious socioeconomic issues like disputes and raising price for water etc. changes in monsoon patterns cause water stress, decrease in the availability of water in the lakes and rivers of asia and africa (ipcc, 2007) causing negative impacts on fish migration, spawning and seed availability for farmers which will also produce less water retention time in non-perennial water bodies (goswami et al.,2006). in terms of fisheries, african countries are more vulnerable state due to the combined effects of predicted warming, the relative importance of fisheries to regional economy and nutrition coupled with limited societal capacity to adapt to potential impacts and opportunities. besides, increasing number of extreme climatic events will have serious repercussions on the ecology and biodiversity of inland water bodies, besides the socio-economic losses. impact, vulnerabilities and risks the impacts of climate change on freshwater ecosystems is always complex, not fully understood and often beyond prediction. however, all these impacts will lead to changes in the quantity, quality, and timing of water. changes will be driven by shifts in the volume, seasonality, and intensity of precipitation; alteration of surface runoff and ground water recharge patterns; changes in evapotranspiration; increased air and water temperatures; and rising sea levels and other extreme climatic events. in the tropical regions, all these together will lead to a number of key eco-hydrological impacts on freshwater ecosystems including increased low-flow episodes and water stress in some areas; shifts in timing and intensity of floods; increased evaporative losses, especially from shallow water bodies; saltwater intrusion in coastal, deltaic, and low-lying ecosystems, including coastal aquifers; more intense runoff events leading to increased sediment and pollution loads; and increased extremes of water temperatures (wwf, 2010). the possible impacts of climate change in aquatic ecosystems are discussed. hydrological cycle climate and water cycle are inseparably linked and every change in the climatic system induces a change in the water system, and vice versa. the climate change would impact precipitation, sea level, river flow, soil moisture, evapotranspiration, and ground water, thereby impacting the quantity and quality of freshwater availability (kundzewicz, 2008). several studies point towards the impact of climate-driven factors on the recent evolution of the water cycle at large scales (bindoff et al., 2013), particularly on precipitation (zhang et al., 2007) or evapotranspiration (douville et al., 2012). the studies in india also indicate the possible implications of climate change on hydrological cycle (mehrotra and mehrotra, 1995), including the western ghats biodiversity hotspot (ramachandra et al., 2013). this points to the research need to enhance the observation network (especially for hydro-meteorological variable such as precipitation, evaporation, snow melt, stream flow, runoff, infiltration) in order to get a quantified estimate of water balance in most of the river and lake basins in asian and africa. ecosystem services and biodiversity 39 east afr. j. biophys. comput. sci., vol. 1, no. 1 climate change has severe projected substantial impacts on ecosystem services. the impacts happen via changes in the distribution and value of water over space and time. such proposed effects will be different depending on the extent of the impact of such changes in the distribution of water and the adaptive capacity of the region's biophysical and social system (chang and bonnette, 2016). overview of ecosystem services that are directly and indirectly impacted by climate change and local anthropogenic impacts is given in figure 2. it show cases the complex, cyclical nature of how the use of ecosystem services can, through direct and indirect mechanisms, affect those same ecosystem services (liu et al., 2015). impacts of climate change on ecosystem services is an area not investigated by the research community in india, despite the fact that it is highly important in planning adaptation strategies. declines in river flows, increased drought and extreme flooding events, and salt-water intrusion are all very likely to result in changes to the composition, structure and function of freshwater ecosystems. in addition, existing stresses on freshwater ecosystems of kerala (e.g. habitat degradation and alterations, habitat loss, altered hydrology, pollution, habitat loss, invasive species, etc) will be aggravated by climate change, increasing the risk of species extinctions and shifts in the provision of ecosystem services. biodiversity in backwaters is disappearing at a much faster pace as a consequence of developmental projects which promote vigorous use of resources and environment and also the ample reclamation of these water bodies result in irretrievable loss of habitat. these backwaters exert serious impact on the coastal fisheries as they serves as nursery and breeding grounds for a variety of coastal fish and shellfish species. encroachment into diverse sections of water bodies including wetlands, paddy fields, lakes etc. are encroached upon in different parts of the state for constructing buildings, houses and resorts violating the laws (nair, 2016). the heavy rain and floods could impact the ecosystem and ecosystem services considerably. in the freshwater ecosystems along the western ghats, the impacts would be much more pronounced. floods may trigger a major shift in the diversity of flora, with invasive species taking over from endemic varieties. the floods also aid in the escape of exotic fish species cultivated in the flood plains to the natural water bodies. it could enhance the threat to rare, endangered and threatened (ret) species, leaving them more vulnerable. 40 east afr. j. biophys. comput. sci., vol. 1, no. 1 figure 2.overview of ecosystem services that are directly and indirectly impacted by climate change and local anthropogenic impacts (adapted from liu et al., 2015). agriculture and animal husbandry india is home to more than 16 per cent of the world population, at the same time harbours only 4 per cent of the world water resources. agriculture is directly dependent on climate and water is a critical component of agricultural vulnerability in india where agricultural production depends on availability of rainwater and water available through irrigation. a warmer climate will accelerate the hydrologic cycle, altering rainfall, magnitude and timing of run-off. warm air holds more moisture and it will result in an increase in evaporation of surface moisture. climate change has a direct impact on crop evapotranspiration, thereby affecting the soil moisture, groundwater recharge, and frequency of flood or drought, and finally groundwater level in different areas. the observed and predicted vagaries of monsoon and the climate driven changes in soil quality would ultimately impact regional agriculture. the multiple impacts of climate change on agriculture are summarised in figure 3. the earlier-anticipated potential benefits of climate change from carbon dioxide would be offset by pollution, serious related climate effects as well as nutrition limitation. 41 east afr. j. biophys. comput. sci., vol. 1, no. 1 figure 3. schematic representation of multiple impacts of climate change on agriculture dev (2011) pointed out that agriculture was less sustainable in the past because of less yields, soil erosion and natural calamities, water and land related problems which made the rural livelihoods susceptible to climate change vulnerability. in addition, rise in sea level will increase the risk of permanent or seasonal saline intrusion into ground water and rivers which will have an impact on quality of water and the agricultural productivity, particularly in belowsea level farming systems in various regions of the world. due to deforestation and increase in sea surface temperature, the temperature across the high ranges and low lands have increased considerably (rao, 2017). vagaries in monsoon may impact the production of economically valuable crops like pepper, coffee, tea, cardamom, banana, ginger and tuber crops. by 2050, the food production is supposed to increase by 60 per cent to meet the increase in demand and therefore any substantial changes in climate would ultimately impact local agricultural productivity (alexandratos and bruinsma,2012) and livelihood. wayanad district experiences low water yield and increasing water stress because of decrease in precipitation and increase in temperature and evapotranspiration due to climate change which is supposed to affect the crops in the district causing reduction in yields and changes in cropping patterns (dinesan, 2017). 42 east afr. j. biophys. comput. sci., vol. 1, no. 1 climate change poses formidable challenge to the development of livestock sector in india. livestock production will be limited by climate variability as animal water consumption is expected to increase by a factor of three, demand for agricultural lands increase due to need for 70% growth in production, and food security concern since about one-third of the global cereal harvest is used for livestock feed (rojas-downing et al., 2017). according to sirohi and michaelowa (2007), “the anticipated rise in temperature between 2.3 and 4.8°c over the entire country together with increased precipitation resulting from climate change is likely to aggravate the heat stress in dairy animals, adversely affecting their productive and reproductive performance, and hence reducing the total area where high yielding dairy cattle can be economically reared. given the vulnerability of india to rise in sea level, the impact of increased intensity of extreme events on the livestock sector would be large and devastating for the low-income rural areas. the predicted negative impact of climate change on indian agriculture would also adversely affect livestock production by aggravating the feed and fodder shortages”. the locally adapted indigenous breeds in india therefore would play a critical role in future towards climate change adaptation. impacts on wetlands wetlands including swamps, mangroves, lakes and marshes play an important role in carbon cycle. while wetland sediments are the longterm stores of carbon, short-term stores are in wetland existing biomass and dissolved components in the surface and groundwater (wylynko, 1999). though wetlands contribute about 40 per cent of the global methane (ch4) emissions, they have the highest carbon (c) density among terrestrial ecosystems and relatively greater capacities to sequester additional carbon dioxide (co2) (pant et al., 2003). in india, coastal wetlands are playing a major role in carbon sequestration. the total extent of coastal ecosystems (including mangroves) in india is around 43,000 km2 (kathiresan and thakur, 2008). overall, mangroves are able to sequester about 1.5 metric tonne of carbon per hectare per year, and the upper layers of mangrove sediments have high carbon content, with conservative estimates indicating the levels of 10% (kathiresan and thakur, 2008). limited analysis on the impact of climate change on wetlands in india suggests that high altitude wetlands and coastal wetlands (including mangroves and coral reefs) are some of the most sensitive classes that will be affected by climate change (patel et al., 2009). in case of the coastal wetlands such as indian part of sundarbans mangrove, rising sea surface temperature and sea level rise due to thermal expansion, could affect the fish distribution and lead to the destruction of significant portion of mangrove ecosystem. further destruction of the sundarbans mangroves would diminish their critical role as natural buffers against tropical cyclones resulting in loss of lives and livelihoods (unesco, 2007; cse, 2012). climate change induced rising temperature and declining rainfall pattern presents a potential danger to the already disappearing lakes in the gangetic plains (sinha, 2011). decreased precipitation will exacerbate problems associated with already growing demands for 43 east afr. j. biophys. comput. sci., vol. 1, no. 1 water and hence alter the freshwater inflows to wetland ecosystems (bates et al., 2008; erwin, 2009), whereas, rise in temperature can aggravate the problem of eutrophication, leading to algal blooms, fish kills, and dead zones in the surface water (gopal et al., 2010). also, seasonality of runoff in river basins such as ganges will increase along with global warming, that is, wet seasons will become wetter and dry seasons will become drier (world bank, 2012). this would have severe adverse impact on affected populations, especially if the seasonality of runoff change would be out of phase with that of demand. impacts on fisheries and aquaculture climate change may affect the hydrology and fisheries of inland waters through increased precipitation, air temperature, and decrease in water quality. the health and productivity of the ecosystems depend upon the fisheries which they are based and are vulnerable to physical and chemical changes in temperature, salinity, acidity and water levels and flows (ipcc, 2007; bindoff et al., 2018). climate change impact pathways in fisheries and aquaculture are detailed in fig. 3. the recent report of food and agriculture organization (fao) indicate that climate change will affect the productivity of the world’s freshwater and marine fisheries, and the impacts on inland sector will be connected to the scarcity and quality of water of natural water bodies. in the aquaculture sector, the short-term climate change can include losses of production and infrastructure arising from extreme events such as floods, increased risks of diseases, parasites and harmful algal blooms, and the long-term impacts can include reduced availability of wild seed as well as reduced precipitation leading to increasing competition for freshwater (barange et al., 2018). fisheries in lakes, rivers, dams and wetlands are affected by changes in rainfall and run-off, rise in temperature, drought, evaporation, intense storms, river flow and several other hydrological parameters which results in water level variations, habitat loss, disease and mortality, alteration of productivity, invasive alien species and species loss. fisheries and aquaculture too contribute to climate change by altering mangroves and coastal wetland ecosystems, and also consume energy required for the production of processed feeds and also to pump water. the outcome of extreme weather events and changes in monsoon pattern storms and floods are huge losses in cage culture systems in rivers and lakes causing large fin fishes to escape (soto et al., 2001).rise in temperature generated by humans on lakes and rivers cause grave threats to various fish species and fish culture production (cheung et al., 2010; fickeet al., 2007) as recognised by the report of intergovernmental panel on climate change (ipcc 2007). according to katikiro and macusi (2012) and xenopoulos et al. (2005) inland fisheries which are artisanal fisheries will be extremely affected by changing water levels and increasing occurrence of dry spells as well as flooding. climate change also causes increase in vaporization, turbidity, reduced solar radiation reaching water bodies resulting in plankton blooms leading to water pollution, run-off due to flooding creating damages to cages and loss of livelihood of fish farmers (anyanwu et al., 2014). rise in temperature due to climate change cause stress in fish and cause diseases. 44 east afr. j. biophys. comput. sci., vol. 1, no. 1 figure 3.climate change impact pathways in fisheries and aquaculture (adapted from badjeck et al., 2010) human health in addition to threats to water supplies for drinking and hygiene, the extent of mosquitoborne diseases may expand due to the impacts of fewer but heavier rainfall events on mosquito breeding. projected changes to surface water hydrology may also lead to more frequent and prolonged toxic algae blooms. reports indicate that in india climate change poses serious threat to public health from extreme weather-related disasters to wider spread of such vector-borne diseases as malaria and dengue (majra and gur, 2009). higher temperature and contaminated water would trigger disease outbreaks and spread of pathogens. vaccine preventable japanese encephalitis epidemic due to rainfall has been reported from himalayan region by partridge et al. (2007) and bhattachan et al. (2009) and to rainfall and temperature in south and east asia (bi et al., 2007; murty et al., 2010). similarly, devi and jauhari (2006), dev and dash (2007), dahal, (2008) and laneri et al. (2010) showed correlations of frequent occurrence of malaria with rainfall which otherwise is influenced by non-climatic variables. increases in heavy rain and temperature will raise the risk of diarrheal diseases, dengue fever and malaria (ipcc, 2014). research linking temperature and health effects in tropical countries is sparse. however, understanding of the current impact of weather and climate variability on population health is the first step for assessing the effects of temperature, rainfall, infectious diseases and extreme weather. socio-economic and other impacts responding to the growing imbalance between water supply and demand has driven changes in water governance, in particular water allocation, in many parts of the world. with a growing population and people living under water stress, particularly for drinking water, there is also 45 east afr. j. biophys. comput. sci., vol. 1, no. 1 likely to be further pressure on individuals and organisations to alter their water use patterns and accept significant changes to the quality and quantity of water provided for different purposes. policy, infrastructure and social changes are likely to be necessary to facilitate adaptation to water scarcity in both rural and urban areas. further, there will be more demands for more desalination plants and recycling and reuse of water from the effluents (ipcc, 2012). changes in the structure and function of rivers, estuaries and wetlands will affect the ecosystem services they provide, with far-reaching social and economic implications. for example, in rural areas, declines in agricultural productivity and shifts in farming are very likely. moreover, salt-water intrusion into estuaries and wetlands may affect coastal fisheries and tourism. water related conflicts may occur regionally due to higher demands for water and scarcity. adaptation, mitigation and management protection of biological diversity of aquatic ecosystems and integrity are important activities to improve the resiliency of aquatic ecosystems so that they continue to provide important services under changed climatic conditions. appropriate adaptation and mitigation strategies would bring community empowerment in the face of climate change vulnerability. global warming, rapid urbanization, industrialization and economic development are the key factors which cause stress and will intensify climate change (reference??). attention among policy-makers is divided about how to minimize the change, how to mitigate its effects, how to maintain the aquatic ecosystems and biodiversity on which societies depend and how to adapt human societies to the changes. maintenance and rehabilitation of ecological integrity of the aquatic ecosystems will inevitably include restoration of health of the ecosystems and the biological resources, not to speak of sustainability of ecosystem services. the ecosystems in good health may remain in few protected areas in kerala, through a long tradition of conservation management that is largely species-based, as amenable to adaptive management. in many cases it may be perceived as the richness of plant and vertebrate communities and this often forms a focus for planning. the need of the hour is preparation of a data base on impacts of climate change on each specific kind of aquatic ecosystem and prioritize its management. in the case of freshwater biodiversity, adaptation strategies that maintain wellfunctioning ecosystems are pivotal. this is achieved through enhancing resilience, removing or managing existing stressors, and maintaining diverse and well-connected mosaics of ecosystems (i.e. aquatic, riparian and terrestrial components) across the landscape. surface and groundwater resources are essential to freshwater biodiversity and aquatic ecosystem processes. appropriate management is critical. over-allocation of water resources represents a major obstacle to implementing suitable adaptation strategies for protecting freshwater biodiversity. mitigation measures include efforts to develop integrated water management strategies along with water saving technologies, increasing water productivity and water reuse to adapt to climate 46 east afr. j. biophys. comput. sci., vol. 1, no. 1 change (ipcc, 2014). however, most of these efforts in developing countries are land-based and therefore fresh efforts are required for mitigating impacts of climate change. negative repercussion arises in natural ecosystems and carbon sequestration when we prevent nature to take its own course to changing conditions as we build sea walls, channels, bunds and dams for agriculture and human settlement (ipcc, 2014). the freshwater areas under protected area network are comparatively less in tropical countries and there is an urgent need to conserve highly threatened ecosystems, especially all the remaining mangrove ecosystems. further, the afforestation initiatives in the ecologically sensitive areas along with integrated watershed management programmes will go a long way in adaptation process. beyond the intrinsic value of wild species and ecosystems, ecosystembased approaches to adaptation aim to use the resilience of natural systems to buffer human systems against climate change, with potential social, economic, and cultural co-benefits for local communities (ipcc, 2014). various downscaled tools to support, formulate, and implement climate change adaptation policy for local governments are under development. one of the major tools is vulnerability assessment and policy option identification with geographical information systems (gis). these tools are expected to be of assistance in assessing ecosystem based adaptation options by examining estimated impacts and identified vulnerability for aquatic ecosystems. while top-down approaches provide scientific knowledge to local actors, community-based approaches are built on existing knowledge and expertise to strengthen coping and adaptive capacity by involving local actors (van aalst et al., 2008). at the same time community-based approaches may have a limitation in that they place greater responsibility on the shoulders of local people without necessarily increasing their capacity proportionately (allen, 2006). more community reserves and community-managed watersheds and ecosystems would not only ensure sustainability, but also provide avenues for adaptation for the stake holders. in the fisheries sector, some of the impacts of climate change are likely to be positive. for example, increased precipitation could reduce current water stress in some regions and also lead to the expansion of habitats available to fish, leading to higher abundances and potential yields. taking advantage of new opportunities could require investment in infrastructure and equipment, for which external support may be required. in cases of both new opportunities and negative impacts, a key requirement for nearly all countries and regions will be to ensure flexibility (within the limits of sustainable use) in policies, laws and regulations. this flexibility will then allow fishers to switch between target species and adjust their fishing practices in response to changes in the ecosystems they utilize for fishing. adaptation in post harvest processes will also be important through, for example, the development or improvement of storage and processing equipment. the implemented post harvest processes can increase the capacity and implementation of robust biosecurity systems in order to ensure the quality of fish and fish products through to the consumers, as well as facilitating possible access to higher value markets (barange et al., 2018). the options for adaptation and building resilience in aquaculture should be applied in 47 east afr. j. biophys. comput. sci., vol. 1, no. 1 accordance with an ecosystem approach to aquaculture. they include: (i) improved management of farms and choice of farmed species; (ii) improved spatial planning of farms that takes climate-related risks into account; and (iii) improved environmental monitoring involving users. alternate livelihood options should be provided to the fishermen to adapt to the changing climate scenarios. in addition to emissions reductions from the fisheries and aquaculture sector, there is the potential to store carbon in some coastal ecosystems such as mangroves, sea weed ecosystems, sea grass beds, etc. these ecosystems have the potential to remove and store atmospheric carbon at much greater rates than terrestrial ecosystems (mcleod et al., 2011). some of these systems, such as mangroves also provide additional benefits to communities through flood control, buffering coastlines from storms, water quality, and provide habitat for juvenile fish. therefore, adaptation may address issues not specifically focused on fisheries or aquaculture, such as mangrove restoration for the primary purpose of buffering coastal communities from storm surge and coastal erosion (shelton, 2014). in short, ecosystem-based adaptation recognizes the critical nature of the services that biodiversity and ecosystems provide to human communities and that help build resilience to climate change. incorporating ecosystem-based adaptation into an integrated approach to climate change adaptation can provide longer term, more effective and more cost efficient solutions that support human well-being and a healthy environment. this approach is particularly relevant to the inland water bodies due to the complex and dynamic nature of these systems. knowledge gap climate change research is at its infancy in the state, and one of the major handicap in arriving at better conclusions on the impact is the lack of data over a time scale with regard to the inland ecosystems. sustain and expand existing monitoring networks and data collection on hydrologic and meteorological conditions and water demand is one of the priority areas. similarly there is a need for stronger data on precipitation and river discharge systematically, and management of water flow from dams. a comprehensive bio-monitoring network with clearly defined goals for the state is necessary to fill the gaps in climate change. long-term climate change monitoring datasets are vital and often useful for research on climate change and the information must be shared across the regions. due importance should be given to research with improvised models and other methods to explore and foretell the interactions between climate change, invasive species, habitat fragmentation and ecosystem dynamics and also to identify the stressors and threats which will create an impact on climate change. urgent actions need to be executed at the local (community involvement), regional and national level and for short and long term involving a multi-disciplinary team. information on significant variables like soil moisture, groundwater depth, water quality, water demand (including water budget of aquatic ecosystems), rates of surface water and groundwater withdrawal by each sector, long-range diversions etc. are particularly limited in india which result in limited assessment capability. 48 east afr. j. biophys. comput. sci., vol. 1, no. 1 engaging stakeholders will definitely leads to the success of the programme and proper public awareness should be propagated regarding environmental and health issues. further, ecosystem based conservation plans involving local communities is yet another priority programme to be implemented, together with declaration of more protected areas including fish sanctuaries, which may serve as ‘climate refugia’. in many asian and african countries where tourism is projected as a source for improving economic benefits, maintenance of inland aquatic ecosystems in good health and promotion of responsible tourism would help in sustainable management in the era of climate change. carbon sequestration capacity of the countries should be increased by promoting public transportation, replacement of old machinery with new energy efficient ones, afforestation, reduction of co2 emission from households etc. another challenge is to increase the food productivity using low emission pathway to reduce the impact of climate change. since fisheries is considered as a major source of food while policy formulation, fisheries should come to the forefront but the benefits gained from the sector are often ignored and continue to lack sufficient attention by decision makers in both adaptation to climate change and food security policy formulation. it is also endorsed upon that to minimize the impacts of climate change on fisheries and also to increase the flexibility of the farmers, investments are needed for sustainable artisanal fisheries and market infrastructure to tackle postharvest losses and also to provide economic incentives. top priority should be given for the conservation of existing wetlands and restoration of all freshwater bodies should be undertaken as a major measure to fight against climate change. also science and policy should communicate and interact together to pursue climate change. more studies with state-specific scientific or modelling studies on climate change are needed, especially in a tropical countries, to study the impacts for effective adaptation strategies and policy framework for the region. inland fisheries sector has to be boosted by adapting a suitable technology which is eco-friendly and less hostile. moreover, while taking policy formulations, fisheries and aquaculture sectors need to be directly linked to food security and employment of the rural population. to enhance the development of young professionals in the field of climate change adaptation, the topic could be included in higher education, especially in formal education programs. shaw et al. (2011) mentioned that higher education in adaptation and disaster risk reduction in the asia-pacific region can be done through environment disaster linkage, focus on hydro-meteorological disasters, and emphasizing synergy issues between adaptation and risk reduction. overall, it may be noted that the climate change impacts on inland aquatic ecosystems, though very important in ensuring food security and ecosystem services, they have not received considerable attention by the researchers, planners, policy makers and practitioners. this warrants a critical review of existing management plans for watershed conservation, flood mitigation, environment and biodiversity regulations, covering potential implications of climate change in regional perspective, besides 49 east afr. j. biophys. comput. sci., vol. 1, no. 1 following an ecosystem approach in conservation and mitigation. references alexandratos n. and bruinsma j. 2012. world agriculture towards 2030/2050: the 2012 revision. esa work.pap.12-03.fao agricultural development economics division, rome. 〈http://www.fao.org/docrep/016/ap106e/ap106e.pdf〉 . allen k.m. 2006. community-based disaster preparedness and climate adaptation: local capacitybuilding in the philippines. disasters. 30(1):,81– 101. anonymous 2010. national wetland atlas kerala. national wetland inventory and assessment (nwia)and space applications centre (isro), ahmedabad and kerala state remote sensing & environment centre, thiruvananthapuram. anonymous 2012. india: second national communication to the united nations framework convention on climate change. ministry of environment and forests, government of india, new delhi. anyanwu c.n., osuigwe d.i. and adaka g.s. 2014. climate change : impacts and threats on freshwater aquaculture. j. fish. aquat. sci. 9 (5): 419-424. badjeck m., allison e.h., halls a.s. and dulvy n.k. 2010: impacts of climate variability and change on fishery-based livelihoods. marine policy 34(3): 375383. barange m., bahri t., beveridge m., cochrane k., funge-smith s. and poulain f. 2018. impacts of climate change on fisheries and aquaculture synthesis of current knowledge, adaptation and mitigation options. fisheries and aquaculture technical paper. no. 627. rome, fao. barros v.r., field c.b., dokken d.j., mastrandrea m.d., mach k.j., bilir t.e., chatterjee m., ebi k.l., estrada y.o., genova r.c., girma b., kissel e.s., levy a.n., maccracken s., mastrandrea p.r. and white l.l. 2014. climate change: impacts, adaptation, and vulnerability. usa. bates b.c., kundzewicz z.w., wu s. and palutikof j.p. 2008. climate change and water. technical paper vi, intergovernmental panel on climate change, geneva. bhattachan a., amatya s., sedai t.r., upreti s.r. and partridge j. 2009. japanese encephalitis in hill and mountain districts, nepal. emerg. infect. dis. 15 (10): 1691-1692. bi p., zhang y. and parton k.a. 2007. weather variables and japanese encephalitis in the metropolitan area of jinan city, china. j. infect. 55 (6): 551-556. bindoff n., stott p., achuta rao k., allen m., gillett n., gutzler d., hansingo k., hegerl g., hu y., jain s., mokhov i., overland j., perlwitz j., sebbari r. and zhang x. 2013. detection and attribution of climate change: from global to regional. in: climate change 2013: the physical science basis. contribution of working group i to the fifth assessment report of the intergovernmental panel on climate change. ipcc, cambridge university press, cambridge, united kingdom and new york, ny, usa, pp. 867–952. bonte m. and zwolsman j.j.g. 2010: climate change induced salinisation of artificial lakes in the netherlands and consequences for drinking water production. water res. 44(15): 4411-4424. chandrashekara u.m. 2015. climate change mitigation strategies in the forestry sector of kerala, india. international journal of advancement in remote sensing, gis and geography. special issue on forest and climate change. int. j. adv. remote sens. gis geogr. 3 (1): 29-37. issn 2321–835. chang h. and bonnette m.r. 2016. climate change and water-related ecosystem services: impacts of drought in california, usa. ecosystem health and sustainability. 2(12):e01254. 10.1002/ehs2.1254 cheung w.w.l.; lam v.w.y.; sarmiento j.l.; kearney k.; watson r.; zeller d. and pauly d. 2010. large scale redistribution of maximum fisheries catch potential in the global ocean under climate change. glob. change biol. 16:24-35. cisneros j.b.e., oki t., arnell n.w., benito g., cogley j.g., döll p., jiang t. and mwakalila s.s. 2014. freshwater resources. in: field c.b., barros v.r., dokken d.j., et al. 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vamanapuram river; abstract an understanding of the feeding habits of fish species in natural environment gives clues for selecting the species for aquaculture. it helps in formulating artificial feeds for culturing species under artificial conditions for small scale or large scale aquaculture. the main objective of the present study was to find the food preferences of fish species in different ecological niches such as low land streams, riverine and estuary. stomachs were cut, food items removed and stored in 4% formalin. diet breadth was calculated as per the standard methods widely recommended. the diet breadth calculated for the fish assemblages in vamanapuram river showed that puntius amphibius has the highest breadth of 6.64. the surface feeding fishes had low diet breadth which ranged from 1.131.83. their main food has been observed to be terrestrial insects. the generalists like rasbora daniconius and puntius filamentosus have diet breadth of 3.27 and 4.15, respectively. whereas fish species found in estuarine habitats showed diet breadth range from 1.00 to 2.82. the fishes present in the upper regions of the river habitat were observed to have low diet breadth than lowland streams. in general, high diet breadth values were observed during february to may. the breadth of barilius bakeri showed minor variations among the three seasons (1.00 to 1.20). based on the diet breadth, the majority of the fishes in vamanapuram river generalists.. introduction the diet breadth of fish species in a community explains the spectrum or range of food items consumed by the fishes. the variations in diet breadth can be used to classify the fishes as specialist and generalist (saswata maitr et al., 2019). high breadth shows a generalistic mode of feeding and low values indicate more specialistic nature. in riverine ecosystems, because of the dynamic nature, and with varied habitats the fishes have adaptations to feed on variety of food items. several studies pertaining to the diet breadth of fish species of different indian rivers and streams have been carried out (arunachalam et al., 1988; arun, 1992; david kingston, 1992; david kingston et al., 2011). the diet breadth of srilankan streams, studied east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx 27 diet breadth of fish communities in vamanapuram river, kerala, south india fishes; research article mailto:drpnatarajan123@gmail.com east afr. j. biophys. comput. sci., vol. 2, issue 1 by moyle and senanayake (1984) showed that most of the species had narrow diet breadths. julio cesar saoliveira et al. (2014) studied diet and niche breadth and overlap in fish communities within the area affected by an amazonian reservoir in brazil. heng et al. (2018) reported the diet breadth and dietary overlap between three commercially important food fishes of cambodia. in the present study, the diet breadths of different fish species from the riverine stretches of vamanapuram river, south kerala, india have been studied in detail. materials and method vamanapuram river is one of the major rivers in kerala with a catchment area of 787 square kilometre located in thiruvananthapuram and kollam districts of kerala state, india. it is found at latitude of 8 ̊ 35’ 24’’ n and 8 ̊ 49’ 13’’ n and longitude of 76 ̊44’ 24’’ e and 77 ̊12’ 45’’ e. the area is characterized by lateritic uplands with intermittent valleys. the altitude ranged from 40m to 300m. it originates from ponmudi hills (1074 m above sea level) flows onwards through vamanpuram town, and joins the kadinamkulam backwater and then enters to the arabian sea at mudalapallipozhi near perumathura, 25 km north of thiruvananthapuram city. the climate is typically sub-equatorial with three main seasons, the premonsoon (februarymay), monsoon (june september) and postmonsoon (october january). the premonsoon and later part of the post-monsoon periods are usually dry (pisharody, 1987). twelve sites were chosen for sampling throughout the vamanapuram river from the lowlands to mouth of the river. the study sites were selected in different habitats like lowland streams (habitat i), riverine (habitat ii) and estuary (habitat iii). among the 12 study sites, seven were lowland streams three riverine and two estuarine stations. for trophic estimates, fishes were collected using monofilament gill nets. depending on the habitats, depth of water column and availability of fishes, gill nets of varying mesh sizes were used. a uniform effort of 20 minutes was set for all the nets at all habitats during 10 am in the morning. soon after the net is hauled, fishes were removed and anaesthetized in 50ppm benzococaine to prevent the regurgitation of food particles. then the fishes were transferred to 4% formalin for preservation. large sized fishes were injected with formalin using a hypodermic syringe and then preserved in 4% formalin. thirty two (32) fish species representing 17 genera were collected during the study period. dietary analysis was done on each individual fish. the fish were cut open and guts removed. the contents of the stomach or intestine up to the first bend and if no stomach was present the gut was pressed in a gridded glass slide and examined using dissection microscope. the minute and microscopic items were observed in high power microscopes. the diet breadth was calculated using the formula of levins (1968): b = 1 / pij, where pij is the proportion of the food in each category. results and discussion thirty two (32) fish species representing 17 genera were collected during the study period (table 1). among the 32 species available in the vamanapuram river, puntius amphibious (pa) 28 east afr. j. biophys. comput. sci., vol. 2, issue 1 showed the highest diet breadth of 6.64 (table 1). this species was observed to be a bottom feeder and it had affinity for a wide range of food items. another bottom feeder, garra mullya (gm) had a diet breadth of 2.21, whose main food items were small algae and filamentous algae. the morphological adaptation of this species especially mouth structure was more suited for the bottom feeding nature. other bottom feeding fishes like etroplus maculatus (em), mystus montanus (mm), puntius melanampyx (pm), mystus armatus (ma), puntius ticto (pt) and puntius vittatus (pv) had diet breadths ranged from 2.78 5.31. of all the bottom feeding fishes garra mullya (gm), puntius ticto (pt) and puntius vittatus (pv) came under category one in which their diet breadths was more or less in the same vicinity. the surface feeding fishes like danio aequipinnatus (da), barilius bakeri (bb) and aplocheilus lineatus (al) had diet breadths of 1.83, 1.18 and 1.13 respectively, and they relied more on terrestrial insects as their main food. the generalists fish groups such as rasbora daniconius (rd) and puntius filamentosus (pf) had diet breadths of 3.27 and 4.15 respectively. the estuarine fishes had diet breadth values ranged from 1.00 2.82. out of these, 42.5% had low diet breadth values (< 2.00). in general, the riverine habitat had low diet breadths than lowland stream habitats. pa showed highest breadth in habitat-i (6.68) followed by mystus montanus (mm) (5.31) and puntius melanampyx (pm) (5.14). the surface feeders danio aequipinnatus (da), barilius bakeri (bb) and aplocheilus lineatus (al) had diet breadths of 2.08, 1.20 and 1.13 respectively. while comparing the breadth values of habitat-i and habitatii, with the exception of puntius ticto (pt) (3.59) and labeo dero (ld) (1.58), all other species in the riverine habitat had low breadth values than lowland stream habitat. in the estuarine habitat, diet breadth values were very low (1.00 2.42) indicating the dominance of specialists. the fish assemblages of vamanapuram river had wide temporal variations in diet breadth (figure 1). in general, high breadth values were observed during premonsoon season. the breadth of puntius amphibious (pa) during premonsoon was 6.28, whereas 4.17 during postmonsoon. the increased number of diet breadth was due to the concentration of food materials in place due to reduced water flow during premonsoon months. in species like da, bb, ps and al, the breadth values had an increase during monsoon and there was further a reduction during postmonsoon due to increased water flow during monsoon months and reduction of water flow during post monsoon months. 29 east afr. j. biophys. comput. sci., vol. 2, issue 1  table -1. diet breadth of fish species in vamanapuram river (mean count ) species habitat i habitat ii habitat iii overall diet breadth puntius amphibious (pa) 6.68 5.80 6.64 puntius filamentosus (pf) 4.14 3.87 4.15 danio aequipinnatus (da) 2.08 1.28 1.83 rasbora daniconius (rd) 3.33 2.06 3.27 puntius ticto (pt) 3.52 3.59 3.41 puntius vittatus (pv) 2.78 2.78 puntius melanampyx (pm) 5.14 5.14 garra mullya (gm) 2.44 2.00 2.21 puntius sarana (ps) 2.54 2.54 barilius bakeri (bb) 1.20 1.02 1.18 etroplus maculatus (em) 4.36 2.44 1.00 4.29 mystus armatus (ma) 4.83 4.83 mystus montanus (mm) 5.31 5.31 amblypharyngodon microlepis (ap) 4.16 4.16 labeo dero (ld) 1.45 1.58 1.53 aplocheilus lineatus (al) 1.13 1.13 ambassis gymnocephalus (ag) 2.77 1.22 1.62 gerres oblongus (go) 1.51 1.51 stolephorus commersoni (sc) 1.13 1.13 carangoides malabaricus (cm) 2.42 2.42 therapon jarbua (tj) 1.00 1.00 etroplus suratensis (es) 2.82 2.82 hemiramphus xanthopterus (hx) 1.00 1.00 sillago sihama (ss) 1.00 1.00 upeneus vittatus (uv) 1.00 1.00 leiognathus equulus (le) 1.34 1.34 johnius aneus (ja) 1.00 1.00 sphyraeno jello (sj) 1.00 1.00 liza tade (lt) 1.22 1.22 xenentodon cancila (xc) 1.22 1.22 glossogobius giurus (gg) 1.00 1.00 channa gachua (cg) 1.00 1.00 only very few species showed temporal consistency in diet breadth. in bb, the breadth was almost consistent with minor variations (1.00 1.31) among the three seasons. the diet breadth of gerres oblongus (go) varied between 1.00 during premonsoon and 1.47 during post monsoon. during the postmonsoon, when more number of estuarine fishes was caught and the east afr. j. biophys. comput. sci., vol. 2, issue 1 breadth of most of them was 1.00. based on the diet breadth, the fishes in vamanapuram can be classified as specialists (b < 3.00) and generalists (b > 3.00) and out of the 16 species occupying the freshwater region, 7 were specialists and 9, generalists. out of the 7 specialists, 3 species were specialised to feed on the surface and 4 on bottom. among the surface feeding specialists, da was an important member of the community since it contributed to 13.55% of the total fish collected. according to arunachalam et al. (1988), this species was a typical specialist feeding on the terrestrial insects. barilius bakeri (bb), another specialist had a diet breadth of 1.18 and al, 1.13. fig. 1: seasonal variations in diet breadth of fish species in vamanapuram river the bottom specialists were pv (2.78), gm (2.21), puntius sarana (ps) (2.54) and ld (1.53). among these, pv, gm and ps were herbivores feeding mainly on plant matter whereas ld was a carnivore feeding mainly on chironomid larvae. the important generalists were pa (6.64), pf (4.15), pm (5.14), pt (3.41) and amblypharyngodon microlepis (ap) (4.16). among these, pt and ap were herbivores. most of the estuarine fishes were specialists feeding on fish. temporal variations in diet breadth were noticed in almost all species and in general it was rather high during premonsoon season. according to welcome (1979), differential prey availabilities, optimal foraging or interspecific competition could explain changes in diet breadth of a fish. the seasonal variations observed in the present study may be due to the differential food availabilities. arunachalam et al. (1990) reported relatively low densities of invertebrates during the monsoon (wet) season in the stream pools of kallar river. various studies show that food availability was low during the dry season i.e. premonsoon in the present study (zaret and rand, 1971 and power, 1983 in panama; matthes, 1964 in zaire). the high diet breadth values observed during premonsoon may be due to the low food 0 1 2 3 4 5 6 7 pa pf da rd pt pv pm gm ps bb em ma mm ap ld al ag go sc cm tj es hx ss uv le ja sj lt species di et b re ad th premonsoon monsoon postmonsoon 31 east afr. j. biophys. comput. sci., vol. 2, issue 1 availability of their choice and fishes switched over to other items of food. on the other hand, moyle and senanayake (1984) hypothesised that the relative consistency of the environment during dry season enabled the development of autochthonous food. this fact may also be true in the present study for the high diet breadth values noticed during dry season. the breadth of pa during premonsoon and monsoon were found to be 6.28 and 6.35, respectively. the breadth was 4.17 during post monsoon. during post monsoon the fish consumed a major percentage of small algae whereas in other seasons it consumed more of chironomid larvae. similarly, pf had a diet breadth of 5.59 during premonsoon whereas during monsoon and postmonsoon, it was 3.18 and 3.65 respectively. similarly, pt, pm and em also showed relatively high values during premonsoon season. comparing the diet breadth values of fish species in different habitats, habitat -i showed high values. the exceptions were pt and ld. the high segregation of bottom feeding fishes in riverine habitat observed in food overlap studies supports the high specialisations (low breadth values) noticed in this habitat. the interspecific competition may also be responsible for the high diet breadths observed in habitati, since species richness is high in streams and more competition for the available food. e. maculatus (em) had the maximum difference in diet breadth between the habitats (habitat i 4.36, habitatii 2.44 and habitat iii – 1.00). it consumed more filamentous algae and littoral vegetation (58% and 23%, respectively) in riverine habitat. in the stream habitat, its food was mainly chironomid larvae (41%). another fish which displayed much spatial difference in its food spectrum was rd (3.33 and 2.06 in habitat i and habitat ii, respectively). the difference lies in the fact that the fish consumed a high percentage of terrestrial insects (67%) in the riverine habitat whereas it consumed a lower percentage (45%) of the same in the stream habitat. the streams which have comparatively more canopy cover are supposed to harbour more of terrestrial insects than the river habitat. moreover, the trend is reverse with this fish in the present study. a similar reverse trend is observed in da also. thus the quantity of terrestrial insects available per fish is higher in rivers than in streams which in turn may be a factor for the high consumption of terrestrial insects in rivers. conclusion vamanapuram river, one of the major rivers of kerala, is rich in fish species. the diet breadth study undertaken for different fish species of the river showed that the food preference greatly relied on habitat preference and feeding habits of the fish. both specialists and generalists are found in the habitats. in general, the riverine habitat showed low diet breadths than lowland stream habitats. estuarine fishes showed very low diet breadth indicating the dominance of specialists. puntius amphibious showed the highest diet breadth followed by mystus montanus and puntius melanampyx. acknowledgements the senior author is thankful to professor p.natarajan, the then head of the department of aquatic biology and fisheries, university of kerala, india, and dr. koos vijverberg, limnological research institute. specicial thanks also extend to the netherlands for their support and advice in carrying out this research work under the collaborative research project ‘river ecology, india’ sponsored by nioo and 32 east afr. j. biophys. comput. sci., vol. 2, issue 1 the office of the international co-operation of the university of leiden, the netherlands. references arun l.k. 1992. niche segregation in fish communities of a south indian river, ph.d. thesis, university of kerala, trivandrum, india. arunachalam m., madhusoodhanan nair k.c., vijverberg k. and kortmulder k. 1988. food and habitat usage of cyprinid fish assemblages in stream pools of a south indian river. internal report no. 1988 – 1990. limnologisch institute, nieuwersluis, the netherlands 89p. arunachalam m., madhusoodhanan nair k.c., vijverberg k., kortmulder k. and suriananarayanan h. 1990. substrate selection and seasonal variation in densities of invertebrates in stream pools of a tropical river. hydrobiologia. 213:141-148. david kingston s. 1992. niche segregation of fish assemblages in vamanapuram river. ph.d thesis, university of kerala, india. heng k., chevalier m., lek s. and laffaille p. 2018. seasonal variations in diet composition, diet breadth and dietary overlap between three commercially important fish species within a flood-pulse system: the tonle sap lake (cambodia). plos one 13(6): e0198848. https://doi.org/10.1371/journal.pone.0198848 julio cesar sa-oliveira, ronaldo angelini and isaac victoria 2014.diet and niche breadth and overlap in fish communities within the area affected by an amazonian reservoir(amapa, brazil). anais academia brasileira de ciencias, 86(1):383-406. levins r. 1968. evolution in changing environments. princeton univ. press, n.j.,usa. matthes h. 1964. les poisons du lac tumba et de la region d’lkela. etude systematique et e’cologique. annales musee’ royal de l’afrique centrale, sciences zoologiques. 126:1-204. moyle p.b. and senanayake, f.r. 1984. resource partitioning among the fishes of rainforest streams in srilanka. journal of zoology (london). 202 : 195 – 223. pisharody p.r.1987. monsoon vagaries over kerala. in : p.natarajan, h.suryanarayanan and p.k. abdul aziz (eds.). advances in aquatic biology and fisheries, trivandrum, india. 361367 power m.e. 1983. grazing responses of tropical freshwater fishes to different scales of variation in their food. env. biol. fish. 9: 103-115. saswata maitra, mahadevan harikrishnan and balachandran nidhin,2019.feeding strategy, dietary overlap and resource portioning among four mesopredatory catfishes of a tropical estuary.j. fish biol.96:130-139 welcome r.l. 1979. fisheries ecology of floodplain rivers. longman. london. zaret t.m. and rand s. 1971. competition in tropical stream fishes. support for the competitive exclusion principle. ecology 52: 336-342. 33 cover v2.pdf (p.1) cover.pdf (p.1-2) slide number 1 blank page.pdf (p.2) table of contents vo 2.pdf (p.3-5) all articles vol 2.pdf (p.6-81) volume 2 issue 1_ 6 articles_4_3.pdf (p.6-91) 4_captive fish_anna results and discussion references 3_reproductive disorder 6_diet bredth_prof. nat 8_ground water_jeeva base boundary map was prepared using survey of india topo-sheets of the study area, and data such as rainfall, geomorphology, geology and land use were collected from central and state government agencies. during field study, groundwater samples were ... 10_ethnoveterinary following comments dagne et al_ challenging students’ performance through practical skills assessment.pdf (p.73-82) guideline to authors_ eajbcs.pdf (p.82-90) back cover.pdf (p.91) introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction east afr. j. biophys. comput. sci. (2022), vol. 3, issue. 2, 25-39 *corresponding author: birhanu kagnew email: birhan444@gmail.com, +251930604047 https://dx.doi.org/10.4314/eajbcs.v3i2.3s plant species composition and community perception towards landscaping work executed at hawassa university-main campus, ethiopia birhanu kagnew * and firew kebede keywords: landscape; beautification; greening; campus; perception; community abstract landscaping is making visual improvements to academic institutions, urban and other private organizations with plants and attractive materials. people all over the world are attracted to green and beautiful landscapes which initiate them to be happy and creative. especially students in higher educational institutions who spend much of their time focused on their studies need of clean, green and attractively well-designed landscape in their campus. so far data on plant species composition and perception of university towards landscape work is lacking. with this understanding, the study was conducted to investigate plant species composition and community perception towards landscaping work executed at hawassa university’s main campus using questionnaires, interviews, observation and group discussion methods. in addition, vegetation data were collected using systematic sampling method. in the study, 221 respondents were drawn from academic staff, administrative workers and students using random sampling method. key informants were selected using purposive sampling method. in order to identify the plant species, systematic sampling along the transect line was employed. twelve (12), 40m x 40 m (i.e. 1600 m2) area quadrat plots were laid and all the plants species in the quadrats were collected and identified. the distance between each transects and quadrat was 200 m and 100m, respectively. 52 plant species with 44 genera and 29 families were recorded. the study showed that, the most dominant family was fabaceae with 9 species followed by cupressaceae as well as moraceae with 4 species each respectively. the results revealed that, campus landscaping work was the most significantly important and made the campus more attractive by plantation (61.1%), landscaping (27.1%) and walkways (5.7%). plantation could also modify the micro-climate of the campus environment (94.3%) due to the plants photosynthesis process which produces o2 and takes in co2 from the atmosphere. in general educational institutions landscaping need to be encouraged to enhance the teaching-learning process, and to make the working environment attractive. a great educational environment is guided by the most powerful teacher of all, nature itself. introduction the global physical landscape is changing due to the process of urbanization. according to the united nations department of economic and social affairs (2014), about 54% of the world's populace resided in city/urban regions in 2014. lands are modified to make useful for residential, commercial, public gatherings, industrial and institutional zones; encouraging population migration to gain access to these facilities. gradually the shrinking of urban green spaces/areas results in the loss of east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx department of biology, college of natural and computational science, hawassa university, hawassa, p.o.box 05, ethiopia research article east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 26 biodiversity and disturbance to the natural ecosystem (izyan et al., 2017). the ecologicalization of plant life landscape want to ensure the rich species and diverse shapes of campus flora, and the plant configuration is affordable, the usage of vegetation to decorate the campus environment to ensure the stability and balance of campus environment and reach the coordination of artificial environment and natural environment (habib et al., 2016). the campus planning and panorama layout should fairly adopt circulate concept, ecological recuperation idea and occasional carbon idea to make college campus come to be harmonious ecological campus from macro views (horhota et al., 2014). a development of green infrastructure (gi) on the university compound has been acknowledged as one of the foundations of education for sustainable development (esd), an initiative that could provide various benefits to the campus community. the students and the campus community are the primary beneficiaries in several aspects which contribute to the enhancement of knowledge, skills, as well as physical and mental replenishment from sustainable landscaping, greening, and beautification work (izyan et al., 2017). landscaping is the process of making visual improvements to academic institutions, urban and other private organizations with plants and attractive materials (amy, 2009). landscaping, greening and beautification in better instructional establishments and faculties can be traced to the very starting of formal education, thinking about it very vital components of the total plan (jellico, 1966; boughman, 1992). landscaping, beautification and greening are completed to create the highquality aesthetic feature, appropriate environment and to supply a naturalized placing the usage of nicely matched herbal or man-made materials. the desired quality of beautification can be made via the affiliation of plant life, shrubs, timber, lawns, fences, houses, pavement, and water (boughman, 1992; mcconnell et al., 2003). large bucks have been spent on landscaping to fulfill mankind’s preferred fine and beautiful environment. plantation of wood, vegetation, shrubs and water offer residing quarters with non-violent and comfy surroundings that are pondered in houses, organizations, authorities places of work, church homes, and academic facilities (boughman, 1992). an adorable bodily environment satisfies the student's emotional and cloth wishes and stimulates non secular increase. a scholar's capability to look and admire physical splendor is nurtured via the manner of his/her surroundings. actual colleges have the potential for attracting beauty to high school community and then transmitting it to the related buddies (brown, 1983). a college campus made attractive by landscaping, greening and beautification is a concept to all of the university network and the parents. the purpose of landscaping at university and faculties are to beautify the surrounding physical surroundings, to offer shade, assist the coaching mastering strategies and to inspire students to love and admire the environment (malone and tranter, 2003; dyment and bell, 2007; habib et al., 2016), because the campuses are social group, and that they play a giant position in converting peoples’ life-style. according to wells (2000), panorama may also alter the micro-climate of the environment surrounding the campus due to the plants photosynthesis system which produces oxygen and absorbed carbon dioxide from the east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 27 atmosphere. landscape and plants gives an appealing element through the way of aesthetic value (rasidi et al., 2013). an attractive landscaping, greening and beautification plays a vast position in minimizing emotional stress, negative emotions, physical pressure, growth fine thoughts among college students and initiate the scholars’ interest toward getting to know, due to the fact, flowers affect human psychology (han, 2009). maintainable landscaping and beautification practices can help to lessen pressure and improve the overall health of humans living in town, college, campus and other organization environments, and may be significantly less expensive to hold. therefore, developing an advantageous dating between a man and the environment may want to have extensive benefit closer to mental balance, enhancing the behavior and improving health situations. furthermore, interaction with none restrict with lovely outside environment may want to reduce mental strain in humans daily lifestyles (harting et al., 1991; kaplan, 1995; kaplan et al., 1998; wells; 2000; taylor et al., 2001). a university campus is just like a small city with infrastructure (such as buildings, transportation, electricity, roads, beautiful and pleasant landscape and green compound) because of the complete function, the construction of campus panorama area have to create locations to carry all kinds of sports and make sure that campus space has attractive elements (icadce, 2015). the school grounds, with adequate care (clean, attractive, comfortable, and orderly surroundings) can make major contributions to student progress. preserving a sustainable landscaped campus environment play a considerable position meets the requirements of diverse verbal exchange between teachers and college students under the assorted social historical past of more than one value. the distance spirit can well arouse the feel of identification of instructors and students to campus panorama cause them to experience pride to analyze, live, contact, leap forward in a campus landscape environment, be unconsciously encouraged through the edification of information and boom the experience of belonging of campus are (icadce, 2015). greening is the process of planting trees, herbs and shrubs to transform the living environment into more health, beautiful and suitable place (douglas, 2003; ryrie, 2004). a beautiful and green campus in the end offers an institution the opportunity to take the lead in redefining its environmental way of life and growing new paradigms through developing sustainable answers for the environmental, social and economic needs of mankind. therefore, the main purposes of the study were to assess the community perception towards landscaping work executed at hawassa university main campus. materials and methods study area the study was conducted in the main campus of hawassa university. hawassa university (hu) was established at hawassa on the 25th of april 2000. hawassa university has seven functional campuses, namely; college of agriculture (ac), college of medicine and health’s sciences campus (cmhs), institute of technology (iot) and the main campus (the seat for the top administration) are located in hawassa city. the remaining three, namely wondo genet campus (wcfnr), awada campus and bensa daye campus are situated out of hawassa city. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 28 employed to select lecturers, third-year main campus students, administrative staffs, keyinformants and campus cleaners as representative samples for data collection. a total of 221 informants were randomly selected and 10 key informants were included. questionnaires were prepared and distributed for two hundred twenty-one (221) respondents to collect data on the perception of the community on landscaping and its contribution on education quality, job creation and beautification work in the campus. the amassed plant specimens were pressed, dried and recognized by experienced botanists using the vegetation of ethiopian and eretria extent one to eight (azene et al., 1993; edwards et al., 1995; hedberg et al., 2003; hedberg et al., 2004), then mounted on herbarium sheets and deposited in the lab. in order to collect the plant species, purposive sampling was used and a total of 12 quadrants, 40m x 40m (i.e. 1600 m2 area) along transect line were used. the distance between, each transects and quadrants were 200m and 100m, respectively. from the total of 12 quadrants, all the plants species in the quadrants were collected and identified. data analysis the collected quantitative data were organized, summarized and subjected to descriptive statics. results and discussion the study was conducted at hawassa university’s main campus to assess the perception of hawassa university’s community towards the landscaping work executed at its main campus carried out from 2017 to the present. since its establishment in 2000, the main campus was bare land with hot and hawassa university (hu) is a comprehensive university that is engaged in the provision of allround education, research, training and community service through its diversified areas of the academic units. hawassa university has recently established three centers: “center of excellence for teacher education and educational leaders, academic center of excellence in human nutrition, and science, technology, engineering, and mathematics (stem) center”. it is located 275 km south of addis ababa, the capital city of ethiopia in the sidama region, hawassa city. the main campus was established in 2000. geographically it lies at 070 05’ north, 38029’ east and at 1697m above sea level. the rainfall pattern is characterized by bimodal distribution with spring/”belg” and summer (main) rainy seasons. however, the rainfall is continuously disbursed with one dry season. the mean annual temperature is 19.50c with the minimum average ranging from 9.30c at some point of december to 140 0c at some stage in july and maximum temperature varies from 24 c throughout july to 29.2 c at some stage in march. the land shape is obvious with reddish volcano soil which is right for construction. the present study was conducted at the main campus of hawassa university. methods of data collection the study was conducted in hawassa university’s main campus from 2017 2019 to study the perception of its community on the beautification, greening, and landscaping work that had been done. the data were collected by using both questionnaires and semi-structured interviews (martin, 1995) and site observation. systematic random sampling techniques were east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 29 intolerable climatic conditions, not sufficiently attractive for the teaching-learning process and for the administrative worker, academic staffs, and students to accomplish their regular work effectively (figure 1). thanks to landscaping and greening works done, currently, the seat, shade area and recreational area made a suitable environment for the service intended (figure 1 and 3). the respondents were asked whether they have been ever observed landscape and beatification work in governmental institution in ethiopia. the result indicates that 78.6% of the respondents’ agreed as they are familiar with landscaping, greening and beautification works in governmental institution in ethiopia while 21.4% of the respondents responded as not observed landscaping and beautification works elsewhere (table 1). the respondents observed beautification work in a governmental institution such as university (52.2%), federal office (18%), schools (14.6%), region office (8.2%) and less in zone office 7.0%). the majority of the university community (77.1%) agreed and was satisfied with the beautification, greening and landscaping work of the university whereas 22.9% of the respondents claim that as there are some issues that need more attention than beautification and landscaping work (table 1). figure 1. comparison between past (top) and present (bottom) appearance of the main campus photo by dawit bedhasa, 2006 east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 30 the respondent agrees that campus beautification and landscaping work was the most important and made the campus more attractive by plantation (61.1%), landscaping (27.1%), walk ways (5.7%), seat and shades (4%), and small water pools compared to the previous situation (figure 1, 3 and table 1). each tree helps to fight global warming via reducing the quantity of greenhouse gases within the environment. vegetation in the campus environment provides color to break out the warmth of the sun and additionally they provide green areas for rest, relaxation and pastime or recreation (behe et al., 2005). the respondents also rated the change in the main campus environment as there is drastic change (75.8%) while the rest claimed as beautification, greening and landscaping work doesn’t include all the campus areas (table 1). table 1: the perception of respondents towards beautification and landscaping work done in the main campus information category percentage (%) have you ever observed land scape & beatification work in governmental institution in ethiopia yes 78.6% no 21.4% types of institutions landscape and beatification carried out schools 14.6% federal office 18.0% zone office 7.0% regional office 8.2% university 52.2% are you satisfied with the landscaping and beautification work in the campus yes 77.1% no 22.9% which landscaping and beautification work is most attractive? landscaping 27.1% walk ways 5.7% seat & shades 4.0% small water pools 0.0% plantation 61.1% how do you rate the change on the campus environment? have change a lot 75.8% not that much 17.1% no change at all 7.1% plants planted have significant role in micro-climate modification yes 94.3% no 5.7% landscaping work increases the beauty of the campus agree 97.7% disagree 2.3% landscaping work has created suitable environment for teaching learning process agree 91.4% disagree 8.6% landscaping work has positive contribution for education quality agree 74.5% disagree 25.5% landscaping increases plantation and infrastructure of the campus agree 87.1% disagree 12.9% the seat, shade area and recreational area made a suitable environment for service intended agree 91.4% disagree 8.6% landscaping work create job opportunity for citizens agree 96.2% disagree 3.8% east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 31 attractively designed and well-maintained physical environment of the campus can help to create a positive paramount impression, set up a peaceful mood, and increase assets value. the present study finding also agreed with this concept that, majority of respondents (94.3%) confirmed as plantation have a significance role for environmental micro-climate modification. because, plants regulate the temperature, it is good for refreshment, provide clean air and also good for all image of the campus. hence, almost all respondents (97.7%) agree with landscaping, greening and beautification work increases the beauty of the main campus (table 1). besides creating excellent working environment for the university community, the landscaping, greening and beautification work also contribute a lot for the teaching-learning process (91.4%) and education quality (74.5) through modifying micro-climate, providing shade, recreation areas and serving as reading area (table 1). with the improvement of socialization, integration and popularization of higher education, the substances of education so come to be more massive and they are not confined to books and school rooms. the campus surroundings that students stay in their everyday life are the materials of training as nicely (hartig et al., 1991; tennessen and cimprich, 1995; habib et al., 2016). the modified physical environment surrounding the campus promotes efficiency in the teaching-learning process and contributes to education quality as well as contributes to their aesthetic development. almost all respondents confirmed that, before the start of beautification and landscaping work, it was difficult to stay at the office, even students were traveling to lake hawassa side areas seeking shade and comfortable reading and seating area due to hot temperature. nowadays, landscaping and beautification work increase plantation and infrastructure of the main campus (87.1%) and almost all respondents agreed (91.4%) with the opinion that the seat, shade, and recreation area made a suitable environment for the service intended (figure 1, 3 and table 1). on the other hand, beautification, greening and landscaping work create job opportunities for citizens (96.2%) (figure 3, 4 and table 1). trees for landscaping and beautification the present study revealed that greening and plantation (94.3%) significantly modify the micro-climate of the environment in the study area (figure 3 and table 1). plants are the “lung of urban areas’’ (mcpherson, 2005) due to their ability to remove pollutants from the atmosphere that is breathed by acting as natural filters. powe and wills (2004) reported that plants generate health benefits by reducing the mortality rate and reducing visits to the hospital. ornamental plants made a more pleasant environment for people (akbari, 2002) and people walking around green areas showed reduced stress levels (lohr et al., 2007; ulrich, 1989). higher education institutions’ students’ under exam stress had increased positive feelings and reduced fear and anger when they had view of plants (frank, 2003). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 32 0 1 2 3 4 5 6 7 8 9 10 pl an ts pe cie s d ist rib ut io n fre qu en cy plant family in the study area figure 2. plant family and species distribution frequency from the study area (both exotic and indigenous plants, see appendix) in the present study area, both exotic and native plants were used (appendix). plantation trees used in the study area includes; junipers procera, jacaranda mimosofolia, ficus elastic, phoenix reclenata, borassus aethiopum, acacia species, nerium oleander, hibiscus syriacus, cupressus sempervirens pyramidalis, graviellia robusta, araucaria species to mention a few (appendix). the majority of plants species used for plantation in the main campus belongs to twenty (29) families; dominated by the fabaceae family with nine (9) species and cupressaceae and moraceae with four (4) species each (figure 2 and appendix). the main reason for choosing plants for landscaping such as providing the screen, blocking the unwanted view, modifying temperature, stabilizing soil, and aesthetic value(overall habit or shape of the plants and their foliage, flower, fruit, and bark).thus, diversity of plant species and combination of plant forms, foliage, flowers, fruit and bark can result in creative, artistic display and beautiful landscape composition. plant species indigenous to the country should be incorporated into the landscaping and beautification work. compared to exotic plants, indigenous plant species carries a variety of environmental benefits ranging from reducing erosion, shade, microclimate modification, and these plants would require less overall maintenance, less watering and less intensive management than exotic species currently used on campus landscaping. the plantation of indigenous trees is very important to conserve the plants species and their survival rate is higher compared to exotic plants. the present study finding indicates that the study area is dominated by exotic plants (appendix). therefore, the researchers recommend that planting indigenous plant is more important than exotic trees for sustainable and long-term usage of the landscaping. because, having a larger proportion of native plants would be less expensive to upkeep in the long-run. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 33 effect of landscaping and beautification on teaching-learning processes there is direct dating among the construction of verbal exchange space and the realization of the instructional feature of campus landscape, highquality campus communication area offers a great location for various communique activities in the campus, makes it convenient for carrying out sports which include instructional alternate, extracurricular practice, extracurricular coaching, out of doors exercise, undertaking and sightseeing. the current university college students present range and randomness and numerous forms of conversation space with wealthy gradation meet the requirements of various varieties of customers. from this perspective, campus panorama surroundings, higher realizes the function for education carrier (icadce, 2015). because college days are a vital duration to form the view of existence values, excessive great campus area environment has a lively effect on shaping the thoughts of university college students (habib et al., 2016).the present study finding reveals that campus landscaping, beautification, and greening had a significant effect on supporting the teaching-learning process, job opportunity and recreation, 91.4%, 96.2%, and 91.4% respectively (figure 3 and table 1). plantation and greening assist the teachinglearning process through providing shade, recreational place, increasing staff and students stay at the campus, reading space and modifying the temperature of the environment (figure 3 and table 1). interplay with natural factors such as vegetation, water source or different appealing regions could lessen psychological pressure in humans each day lifestyles. decreased psychological strain could permit advantageous attitudes to broaden and stimulate students learning interest towards studying (kaplan et al., 1998; han, 2009). beautification components, especially flora have active psychological relationship with people, could assist in mental stability, improving the behavior and health conditions (wells, 2000; taylor et al., 2001).. figure 3. landscape designing and walk ways in the main campus east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 34 humans have better standard health and immunity to diseases while dwelling in an area with considerable inexperienced space, and patients recover faster when a view of a natural environment is available (maas et al., 2006; maller et al., 2002). beautiful environment enhance the aesthetic value of the campus environment and reduce the surrounding temperature and help to get clean air (malone and tranter, 2003). hence, almost all respondents (97.7%) of the present study appreciate the landscaping and beautification work done in the study area (table 1). job opportunities before landscaping and plantation work started hawassa university’s main campus was bare lands, hot and inconvenient for teachinglearning process, academic staff, students and administrative workers to accomplish their daily activity properly. the majorities of main campus students especially prefer to seat and read at lake hawassa sides. nowdays, the campus appears as one of the most beautiful and attractive campuses in the country (figure 1 and 3).even the campus is becoming preferable a film shot and another activity area. figure 4. partial view of landscaping, beautification and greening workers in the main campus. beautification, greening and landscaping work in the campus started in 2012 g.c and continue to present with the support of the germany government that support around 74 million birr, and beatified by flora agricultural state plc aa (personal communication with campus beatification officer). since beautification started, different activities were carried out in the main campus such as planting trees, grasses and protecting them watering, mulching, weeds avoiding, shortening the grass with a sickle, scissors and machines. the study result confirmed that the campus beautification work has created a great job opportunity (96.2%) for more than 80 workers now (figure4 and table 1). however, different challenges interrupt the beautification and greening activities (table 2). the price paid and works are not related and workers are disadvantageous. the study suggests that sustaining the landscaping, beautification, greening and encouraging the workers are crucial (figure 3 and 4). awareness raising activities should be given to the students and campus societies to protect and proud off the campus beautifying and greening. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 35 landscaping and beautification requires significant hand work and the use of a system, relying on the nature of site grounds. however the use of educated labor and higher equipment may also lessen the fee. from 1% 4% of the price range for the campus, the school invested on campus beautification. therefore, setting up an endowment could create a higher financial supply to be available for campus beautification and up maintenance (larry, 1992). seating areas the respondents’ were asked to which facilities they would like to be incorporated to the site and indicated that incorporating seating regions need to be a design priority. respondents were verified the maximum popular option benches (85%), as they would love to look benches brought to the area, indicating a preference to make the space greater interactive and welcoming. at some stage in the focal point group, participants emphasized seating areas as an amazing manner to get students to note and admire the ecological layout features of the site (figure 5). figure 5. desired amenities of respondents in the study area the respondents point out that, comfortable areas where students and the community could seat and examine or do work are the seating regions ought to be as a minimum partly offset from the on foot paths and avenue facets so that they may be not be disturbed by high pedestrian site visitors. figure 5 above also indicates that, green space and landscaping involving native plants species (81%) are more appreciated by respondents. the findings indicate thatthere is support for additional beautification, landscaping and greening with less exotic plant species (figure 5 and appendix). constraints of landscaping, beautification and greening in hawassa university main campus different challenges interrupt the beautification and greening activities (table 2). semistructured interview and questionnaire reports indicate that, the main challenges of landscaping, greening and beautification work of the study area were lack of budget (77.66%), lack of beautification equipment’s (76.10%), absence of nursery on the main campus (56.23%), lack of planting materials, lack of desired amenities of respondents east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 25-39 36 awareness and lack of trained human power (54.73%), (53%)and (51.%) respectively (table 2). table 2: constraints of landscaping, beautification and greening work in the study area challenges frequency percent (%) rank knowledge gap in beautification 51 52.33 6th lack of training for workers 52 51.10 7th lack of water availability 37 41.20 9th destruction by animals 43 49.12 8th lack of budget 82 77.66 1st lack of awareness for university community 45 53.00 5th lack of beautification equipment’s 71 76.10 2nd knowledge gap in plant breeding 31 19.10 10th absence of nursery in main campus 55 56.23 3rd lack of planting materials 57 54.73 4th conclusions a development of green infrastructure on university compound has been acknowledged as one of the foundations of education for sustainable development, an initiative that could provide various benefits to the campus community. the investigation was carried out to assess plant species composition and the perception of hawassa university community towards the landscaping work executed at its main campus since 2017 to present. besides creating excellent working environment for the university community, the landscaping, greening and beautification work contribute a lot for teaching-learning process and education quality through modifying micro-climate, providing shade, recreation place, and serving as reading space. nowadays, landscaping and beautification work increase plantation and infrastructure of the main campus and almost all respondents agreed with the opinion that the seat, shade, and recreation area made a suitable environment for the service intended. the finding of the study also indicates that, the majorities of respondents agree and appreciate that landscaping and beautification work creates enormous job opportunities for citizens. we recommend that sustainable landscaping works to enhance the teaching-learning process make the campus more attractive and refresh the mind of workers and students as it potentially contributes to the quality of education. therefore, all university communities should protect/be proud of the greening and beautification work done. protection and taking care of the plants should be given higher priority. furthermore, the university should use this beautiful environment as an income source (place to shoot films and photos). planting different plant species should continue in consultation with experts in the area (botanists, environmentalists, and horticulture). conflict of interests the authors declared that there is no any conflict of interests. acknowledgement east afr. j. biophys. comput. sci. 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(2022), vol. 3, no. 2, 25-39 39 15 combretum molle r.br. ex g.don, combretaceae tree 3 indigenous 16 cordia africana lam. boraginaceae wanza tree 21 indigenous 17 croton macrostachyus hochst. euphorbiaceae bisana tree 2 indigenous 18 croton megalocarpus hutch. euphorbiaceae kenya bisana tree 1 exotic 19 cupressus lusitanica mill. cupressaceae yefenjitid tree 15 exotic 20 cupressus sempervirens pyramidalis cupressaceae italian cypress tree 53 exotic 21 delonix regia (boj.ex hook.)ref. fabaceae yedirezaf tree 12 exotic 22 duranta erecta l verbenaceae tree >100 exotic 23 ekebergia capensis sparrm. meliaceae lol tree 5 indigenous 24 eriobotrya japonica loquat rosaceae shrub 4 exotic 25 ficus elastic roxb. ex hornem moraceae yegomazaf tree 1 exotic 26 ficus sycomorus l moraceae shola tree 5 indigenous 27 ficus vasta forssk moraceae worka tree 4 indigenous 28 grevillea robusta r.br. proteaceae abeba tree 45 exotic 29 hibiscus rosa-sinensis l. malvaceae shrub 16 exotic 30 jacaranda mimosifolia d.don. bignoniaceae yetemenjazaf tree 70 exotic 31 jatropha curcas l. euphorbiaceae tree 5 exotic 32 juniperus procera hochst ex engl cupressaceae tid tree 16 indigenous 33 leucaena leucocephala (lam.) de wit fabaceae shrub 3 exotic 34 mangifera indica l. anacardiaceae mango tree 5 exotic 35 melia azandrach l. meliaceae tree 14 exotic 36 moringa stenopetala (baker f.) cufod. moringaceae shiferaw tree 1 exotic 37 musa paradisiaca l. musaceae banana/muz tree 20 exotic 38 nerium oleander l. apocynaceae shrub 80 exotic 39 olea europaea ssp. cuspidata (wall.exg.don) cif. oleaceae woyra tree 15 indigenous 40 phoenix reclinata jacq. arecaceae saticho tree 64 indigenous 41 pinus patula l. pinaceae tree 8 exotic 42 plumeria alba l. apocyanaceae yebereha rose shrub 3 exotic 43 psidium guajava l. myrtaceae zeyituna tree 2 exotic 44 senna siamea (lam.) irwin et barneby fabaceae tree 24 exotic 45 sesbania sesban (l.) merr. fabaceae shrub 2 indigenous 46 spathodea campanulata p.beauv. bignoniaceae tree 19+ 24 exotic 47 syzygium jambos l myrtaceae yeferenjigoya tree 9 exotic 48 terminalia brownie fresen combretaceae tree 42 indigenous 49 thevetia peruviana (pers.) k.schum. apocynaceae 14 exotic 50 thuja orientalis l. cupressaceae yefenjitid tree 11 exotic 51 trilepsum madagascare moraceae tree 18 indigenous 52 vernonia amygdalinadelile asteraceae grawa tree 5 indigenous mihret_wendawek_zelalem_phenotypic and allelic distribution of the abo and rhesus blood groups _after proof reading.pdf (p.1-10) jovine emmanuel_the effect of pressure on carbon monoxide oxidation _doi.pdf (p.11-24) birhanu and firew _plant species composition and community perception towards landscaping _doi.pdf (p.25-39) senite and desie_ovine eimeria infection_doi.pdf (p.40-47) eyob and teferi_determination of the levels of some selected metals _doi.pdf (p.48-60) slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 east east afr. j. biophys. comput. sci. (2022), vol. 3, issue. 2, 61-67 *corresponding author: email: zabishwork2@gmail.com, +251 947347121 https://dx.doi.org/10.4314/eajbcs.v3i2.1s dessale alemu1, idris shafi2, tizazu abza*2 1woldia university, department of physics, woldia, ethiopia 2hawassa university, department of physics, hawassa, ethiopia keywords: solution method; doping; crystal growth; harmonic generation; nonlinear optics abstract the aim of this research was to synthesize and characterize pure and magnesium chloride (mgcl2) doped l–alanine cadmium chloride (lacc) single crystals. pure and mgcl2 doped lacc single crystals were synthesized by solution method with slow evaporation solution growth technique at room temperature. the single crystal x-ray diffraction studies of pure, 1 and 2 mol% mgcl2 doped lacc single crystals revealed monoclinic crystal structure with c2 space group. the optical properties of pure and mgcl2 doped lacc single crystals investigated by uv–vis/nir spectrometer confirmed that the crystals were transparent in the wavelength range of 230-1100 nm. the optical band gap energy of pure and doped lacc single crystals were found to have the same value of 5.4 ev. the energy dispersive x-ray analysis indicated the incorporation of magnesium and chlorine atoms in lacc single crystal. the second harmonic generation efficiency of 1 and 2 mol% mgcl2 doped lacc crystals were analyzed by kurtz-perry powder technique and found to be 1.75 and 2 times greater than that of the standard potassium dihydrogen phosphate crystal, respectively. introduction the core attention of nonlinear optical (nlo) studies is to modify the phase, frequency or amplitude of intense electromagnetic input field using nlo materials for photonic applications (boyd, 2019). nonlinear optical materials have been the subject of much research in recent years due to their potential uses on optical computing, laser technology, harmonic generation, optical communication, optical data storage technology, signal processing and manipulation. therefore, currently there is a need to produce high efficiency single crystals of nlo materials (marudhu et al., 2013; raguram et al., 2016). much attention has been paid to organic nlo materials due to their promising properties, such as fast optical response time and high nonlinearity, compared to the inorganic materials. the aggregate of materials which have large nonlinear optical properties with resistance to physical and east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx synthesis, growth and characterization of magnesium chloride doped l-alanine cadmium chloride single crystal: for nonlinear optical application research article https://dx.doi.org/10.4314/eajbcs.v3i2.1s east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 61-67 62 chemical attack has led to the investigation of semi-organic materials (kaliammal et al., 2020). amino acids are favorable organic materials displaying specific features of interest, such as molecular chirality which secures noncentrosymmetric crystallographic structure, absence of strongly conjugated bonds which leads to wide transparency ranges in the visible and ultra-violet spectral regions and zwitter ionic nature of the molecule which favors crystal hardness for applications in devices (natarajan et al., 2006; raguram et al., 2016). l-alanine is an amino acid group that forms a chains of complexes upon reaction with different acids. reports are available on l-alanine based nlo crystals such as: l-alanine cadmium chloride (dhanuskodi et al., 2007), l-alanine acetate (kumar et al., 2005), l-alanine hydrogen chloride (rose et al., 2010), l-alanine sodium nitrate(fleck and petrosyan, 2009), l-alanine potassium chloride (prabha and palaniswamy, 2010) and l-alanine maleate (karunanithi et al., 2012). l-alanine cadmium chloride is an amino acid derivative nlo material with high second harmonic generation (shg) efficiency and it crystallizes in the monoclinic crystal system with non-centrosymmetric space group (jothimani and selvarajan, 2017; radhika et al., 2013). few reports are available on the synthesis of lalanine cadmium chloride single crystals by solution growth method. as far as the authors are aware, there is no report on magnesium chloride doped l-alanine cadmium chloride single crystals. since doping can influence many of the useful properties like, optical transparency, second harmonic generation (shg), crystalline perfection which may in turn influence the physical properties depending on the degree of doping and the accommodating capability of the parent crystal (shkir et al, 2014). magnesium chloride-doped l-alanine cadmium chloride single crystals were grown using slow evaporation, and their structural, optical, second-harmonic generation (shg), and compositional properties were characterized. materials and methods in this work, analytical grade l-alanine (sisco research laboratories, 99%), cadmium chloride (uni-chem, 99%) and magnesium chloride (uni-chem, 98%) were used directly without further process. the parent compound was synthesized by taking an equimolar ratio of lalanine and cadmium chloride that is obtained by dissolving 8.0901 g l-alanine and 22.8353 g cadmium chloride. the calculated amount of lalanine has been dissolved with distilled water in a beaker and placed on a magnetic hot plate regulated at 30°c then cadmium chloride was added. it has been stirred continuously for four hours to obtain hmgenous supersaturated solution. afterwards the solution has filtered by using whatman filter paper into a 500 m1 beaker. the filtered solution has been kept free from dust and other contamination by covering it with porous cover so the rate of evaporation could be minimized. 1 mol% and 2 mol% mgcl2 doped l-alanine cadmium chloride single crystals were synthesized by adding 2.0333 g and 4.0666 g mgcl2 into the parent compound solution respectively. a similar stirring process has been followed for 1 and 2 mol% of mgcl2 doped l-alanine cadmium chloride. after a perid of 30 days, ptically clear transparent crystals were harvested from supersaturated solution. accordingly, the grown pure, 1 and 2 east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 61-67 63 mol% mgcl2 doped lacc crystals were shown in fig. 1. fig. 1. photograhp of (a) undoped, (b) 1 mol% mgcl2 doped and (c) 2 mol% mgcl2 doped lacc single crystals respectively. results and discussion single crystal x-ray diffraction single-crystal x-ray diffraction (xrd) analysis using a bruker axs kappa apexii diffractometer (mo kα radiation, λ = 0.07107 nm) revealed that 1 and 2 mol% mgcl₂-dped lacc crystals adopted a monoclinic structure (with interaxial angles in a crystal lattice of α≈ β ≈ 90° and γ ≈ 116.41°). the calculated lattice parameters (å) were a = 16.282, b = 7.261, c = 8.008 for 1 mol% and a = 16.286, b = 7.268, c = 8.011 for 2 mol% mgcl₂ doping. the unit cell parameters and crystal structure for pure lacc crystal in (å) were a = 16.298, b = 7.259, c = 7.981 and monoclinic respectively as reported by other authors (dhanuskodi et al., 2007). it is observed that both undoped and mgcl2 doped lacc crystals crystallize in same structure however, slight change in the lattice parameters were detected from the doped crystal compared to the pure lacc crystal. the changes in the lattice parameter may be due to the incorporation of mgcl2 in lacc crystal lattice. the grown crystals belongs to space group c2 which is recognized as non-centrosymmetric, thus satisfying an essential material criteria for the shg activity of the crystal (fentaw et al., 2019). uv–vis nir analysis to assess its optical properties, the transmission, cutoff wavelength, and band gap energy of the nlo single crystal were determined. in this study these optical parameters have been studied by using perkin elmer lambda 35 uv-vis-nir spectrophotometer in the wave length range between l90-ll0 nm to cover near ultraviolet, visible and near ir regions. the recorded spectrums were shown in fig.2. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 61-67 64 fig.2. optical transmittance of pure, l and 2 mol % of doped lacc crystals. from the spectrum it is detected that the crystals were transparent in the wavelength range 230 1100 nm. nlo materials can be of practical use only if they have a wide transparency range, thus the optical transmittance range of the grown crystals make them convenient materials for nonlinear optical applications (ahlam et al., 2013; charoen-in et al., 2010). the result confirmed that the lower cutoff wavelength of the crystals were almost the same irrespective of the dopant concentration, however, the percentage of transmittances have increased for 1mol% and 2 mol% mgcl2 doped lacc crystal. the increase in optical transmittance could be due the enhancement in the crystalline quality and absence of major defects as crystalline defect affect the optical properties (jothimani and selvarajan, 2017). the band gap energy was calculated using the relation eg = 1240/λmin, where λmin is the cut-off wavelength of the light which is 230 nm and it was found to be 5.4 ev for pure and doped crystals (raguram et al., 2016). energy dispersive x-ray spectroscopy (edx) analysis energy dispersive x-ray spectroscopy (edx) is a very useful instrument that used to identify the elemental composition of the samples. the incorporation of 1 and 2 mol% of mgcl2 into the crystal lattice of lacc was confirmed by jeol-6390lv scanning electron microscope attached to edx and it is shown in fig.3. the edx spectrum confirmed existance of expected elements such as oxygen, chlorine, magnesium and cadmium in both 1 and 2 mol% of mgcl2 doped lacc crystal. the molecular weight and atomic percentage of identified elements in the doped nlo samples were presented in table1. the measurable (quantitative) and qualitative edx results clearly showed increase in the atomic percentage of mg and cl signifying east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 61-67 65 incorporation of the mgcl2 in the lacc single crystal structure. fig. 3. edx spectrum of 1 and 2 mol% of mgcl2 doped lacc crystals respectively. table 1: energy dispersive x-ray (edx) analysis elements 1mol%mgcl2+lacc 2mol%mgcl2 +lacc weight% atom% weight% atom% ok 74.28 91.19 62.49 82.57 mgk 0.72 0.57 5.41 4.70 clk 10.20 5.65 16.38 9.77 cdl 14.80 2.59 15.72 2.96 total 100.00 100.00 100.00 100.00 second harmonic generation (shg) test the second harmonic generation efficiency analysis of the samples were carried out by kurtz-perry powder technique by packing very fine powder of mgcl2 doped lacc sample in a microcapillary tube and a fundamental beam (1064 nm) from nd-yag laser was incident on the mgcl2 doped lacc crystals (kushwaha et al., 2011). a second harmonic generated green light beam (532 nm) was emerged from the samples. to evaluate second-harmonic generation (shg) properties, potassium dihydrogen phosphate (kh₂po₄, kdp) powder was used as a standard reference material. the transmitted beam voltage through kdp was then measured to be 12 mv. in comparison, the east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 61-67 66 transmitted beam voltages through the 1 and 2 mol% mgcl₂-doped lacc samples were 21 mv and 24 mv, respectively. the shg efficiency of the 1 and 2 mol% mgcl₂-doped lacc crystals was thus calculated to be 1.75 and 2 times greater than that of the kdp reference material. the shg efficiencies of pure lacc single crystal was 0.87 times greater than that of the standard kdp crystal reported by (kalaiselvi et al., 2013). the enhancement of shg efficiency may be either due to the improved in crystallinity or the change in electronic structure of lacc crystals due to the doping of mgcl2 (bhagavannarayana and kushwaha, 2010). the current results indicate that 1mol% and 2mol% mgcl2 doped lacc crystals are the better candidates for nlo applications than the undoped lacc single crystal. conclusion pure and mgcl₂-doped (1 and 2 mol%) lacc single crystals were grown by slow evaporation at room temperature. characterization included single-crystal xrd (confirming a monoclinic structure, space group c2), uv-vis-nir spectroscopy (showing high transmission across the uv-vis-nir range, enhanced by mgcl₂ doping), energy-dispersive x-ray spectroscopy (edax, confirming mgcl₂ incorporation), and second-harmonic generation (shg) efficiency measurements (1.75× and 2× greater than kdp for 1 and 2 mol% doping, respectively). these results suggest that both pure and mgcl₂-doped lacc crystals are promising candidates for nonlinear optical applications. acknowledgement we extend special thanks to the department of physics at university of jammu and amravati university (india) for allowing us to characterize our samples. references ahlam m., hemaraju b., and prakash a.g. 2013. growth and characterization of pure and doped organic nonlinear optical single crystal: l-alanine alaninium nitrate (laan). optik. 124(23): 5898-5905. bhagavannarayana g. and kushwaha s.k. 2010. enhancement of shg efficiency by urea doping in zts single crystals and its correlation with crystalline perfection as revealed by kurtz powder and high-resolution x-ray diffraction methods. j. appl. crystallogr. 43(1): 154-162. boyd r.w. 2019. nonlinear optics: academic press. charoen-in u., ramasamy p. and manyum p. 2010. comparative study on l-alaninium maleate single crystal grown by sankaranarayanan–ramasamy (sr) method and conventional slow evaporation solution technique. j. cryst. growth 312(17): 23692375. dhanuskodi s., vasantha k. and mary p.a. 2007. structural and thermal characterization of a semiorganic nlo material: l-alanine cadmium chloride. spectrochim. acta a: mol. biomol. spectrosc.66(3): 637-642. fentaw d.a., peter m.e. and abza t. 2019. synthesis and characterization of lanthanum chloride doped lalanine maleate single crystals. j. cryst. growth 522: 1-4. fleck m. and petrosyan a. 2009. comments on papers reporting ir‐spectra and other data of alleged l‐alanine alaninium nitrate and l‐alanine sodium nitrate crystals. crystal research and technology: journal of experimental and industrial crystallography 44(7): 769-772. jothimani r. and selvarajan p. 2017. effect of nickel sulphate on growth, structural, optical, mechanical and thermal properties of l-alanine single crystals (lans). paper presented at the iop conference series. materials science and engineering (online). kalaiselvi p., raj s.a.c. and vijayan n. 2013. linear and nonlinear optical properties of semiorganic single crystal: l-alanine cadmium chloride (lacc). optik. 124(24): 6978-6982. kaliammal r., sudhahar s., parvathy g., velsankar k., and sankaranarayanan k. 2020. physicochemical and dft studies on new organic bis-(2-amino-6methylpyridinium) succinate monohydrate good quality single crystal for nonlinear optical applications. j. mol. struct., 128069. karunanithi u., arulmozhi s. and madhavan j. 2012. structural, optical and dielectric studies on pure and east afr. j. biophys. comput. sci. (2022), vol. 3, no. 2, 61-67 67 doped lalaninium maleate single crystals. j. appl. phys. 1: 19-23. kumar r.m., babu d.r., jayaraman d., jayavel r. and kitamura k. 2005. studies on the growth aspects of semi-organic l-alanine acetate: a promising nlo crystal. j. cryst. growth. 275:1935 1939. kushwaha s., vijayan n., maurya k., kumar a., kumar b., somayajulu k. and bhagavannarayana g. 2011. enhancement in crystalline perfection and optical properties of benzophenone single crystals: the remarkable effect of a liquid crystal. j. appl. crystallogr. 44(4): 839-845. marudhu g., krishnan s., thilak t., samuel p., vinitha g. and pasupathi g. 2013. optical, thermal and mechanical studies on nonlinear optical material diglycine barium chloride monohydrate (dgbcm) single crystal. j. nonlinear opt. phys. mater 22(4): 1350043. natarajan s., britto s.m. and ramachandran e. 2006. growth, thermal, spectroscopic, and optical studies of l-alaninium maleate, a new organic nonlinear optical material. cryst. growth des. 6(1): 137-140. prabha d. and palaniswamy s. 2010. growth and characterization of nlo material: l-alanine potassium chloride. rasayan j. chem. 3: 517-524. radhika p., jayakumari k. and mahadevan c. 2013. growth and characterization of pure and oxalic acid doped l arginine acetate single crystals. int j eng res appl. 3: 1841-1849. raguram t., rajni k., shanmugam p. and meiyazhagan s. 2016. synthesis and characterisation of undoped and methyl orange (dye) doped l-alanine acetate single crystal. int. j. chemtech res. 9(7): 678-687. ramajothi j., muraleedharan r. and vinitha g. 2019. investigation of mechanical, thermal and third order nonlinear optical properties of l-alanine cadmium chloride single crystal. int. j. chem. tech. res. 12: 141-154. rose a.l., selvarajan p. and perumal s. 2011. studies on growth and characterization of an nlo crystal: lalanine hydrogen chloride (lahc). mater. chem. phys. 130(3): 950-955. shkir m., riscob b., khan m.a., alfaify s., dieguez e. and bhagavannarayana g. 2014. effect of organic ligands (l-proline and l-methionine) on growth, structural, vibrational, crystalline perfection, shg efficiency, microscopic and optical properties of kdp single crystals. spectrochim. acta a: mol. biomol. spectrosc. 124: 571-578. . east afr. j. biophys. comput. sci. (2022), vol. 3, issue 1, 9-16 *corresponding author:email: bizuwmmh@gmail.com , +25191 1053403 https://dx.doi.org/10.4314/eajbcs.v3i1.2s abdurahman esleman1, bizuneh yirga2*, wondiye aychiluhim2 1research scholar, department of sport science, hawassa university, ethiopia 2department of sport science, hawassa university, ethiopia keywords: aerobic fitness; body composition; cardiovascular endurance introduction physical fitness is the biggest potentiality of the human beings. it cannot be bought; it can only be achieved through day to day physical activity (bharath and mukesh, 2011). regular physical exercise and fitness are critically east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx abstract this study aimed to examine the impact of a 12-week aerobic exercise program on health-related physical fitness variables among grade eleven male students at gonji preparatory school. the study design was experimental method. initially, 242 students aged from 18 to 22 years were purposively selected, but only 108 students fulfilled inclusion criteria of the study. from these, 51 students declined to participate and 57 were willing to participate. for ease of management, only 30 students were selected from these willing groups based on simple random sampling technique,which were then grouped equally into control and experimental groups. experimental group was exposed to aerobic exercises for 40 60 minute a day for 3 days a week during 12-week. both study groups were exposed to 40 minute per week in school regular physical education class during 12-week. study groups had taken pre-test and post-test measurements. paired t-test and independent t-test were used for data analysis. the level of significant was set at p<0.05. statistically significant difference have been detected between the pre-test and post-test values on experimental group in body composition (t=-3.571, p<0.05 and cardio-respiratory fitness (t=-4.258, p<0.05), but control group in body composition (t=-1.786, p>0.05 and cardio-respiratory fitness (t=-0.091, p>0.05) registered no statistically significant difference. the result obtained from experimental group indicated that there were significant differences observed in body composition and cardio-respiratory fitness, but not on control group. based on the current finding, a 12-week moderate aerobic exercise program for 40 60 minute a day for 3 days a week has positive effect on the improvement of physical fitness, but not improvement 40 minute school regular physical education class, so that it needs additional time for physical education class for grade 11 male students in preparatory schools. important for the health and welfare of people of all categories, whether they regularly participate in exercise (usually referred as sport) or some type of moderate health-enhancing physical activities. even among frail adults and very old adults, mobility and functioning can be effects of twelve-week aerobic exercise on selected health-related physical fitness variables on gonji preparatory school male students research article east afr. j. biophys. comput. sci. (2022), vol. 3, issue 1, 9-16 improved through physical activity (butler et al., 1998). correctly performed progressive exercise increases the level of fitness and improves health. it also creates a sense of wellbeing, produce greater energy and reduce the risk of developing many diseases. exercise makes improvements on the body systems over and above normal day to day activities and as a result, the systems adapt anatomically and physiologically (rosser, 2001). aerobic exercise stimulates the cardiovascular and respiratory systems, as well as major muscle groups, resulting in improved physical and mental well-being. consistent engagement in aerobic activities promotes notable physiological changes. specifically, aerobic workouts increase blood flow to various tissues, encourage blood vessel angiogenesis (sprouting of new vessels), and optimize oxygen transport, leading to more efficient nutrient delivery to muscles and waste removal, allowing for sustained activity with less fatigue (shahana et al., 2010). physical education in schools builds students' competence and confidence, enabling them to participate in a variety of physical activities that play a central role in their lives, both within and beyond the school environment. a welldesigned physical education curriculum allows all students to enjoy and excel in diverse forms of physical activity. the time allocated to physical education in the majority of schools has declined with a consequent increase in time allocation for other academic subjects (hillman et al., 2008). unfortunately, many schools have reduced physical education opportunities in order to dedicate more class time to meet these academic standards (lavall, 1984). similarly, the federal democratic republic of ethiopian, the ministry of education has been developed a physical education curriculum in secondary and preparatory schools with a oneday class schedule per week for 40 minutes long for both theoretical and practical sessions. the allocation of periods for secondary, junior and preparatory schools have been limited compared with other country class schedules to ensure and develop student’s optimal physical fitness. in california,schools serving grades 7–12 are required to provide a minimum of 400 minutes of health physical education (i.e sport) instruction over every 10 day period (source:(http://www.cde.ca.gov/ci/cr/cf/ documents/, accessed on june 12, 2019) the objective of teaching physical education curriculum designed by federal democratic republic of ethiopian ministry of education was intended to develop and maintain all aspects of personality such as physical, mental and social wellbeing of students. but, the question is it possible within 40 minutes per week class schedule? according to american college of sports medicine, (2009) participation in at least 30 minutes of moderate physical activity per day carried out 3 days a week will yield significant health benefits. on the other hand, thomas et al. (2004) stated that an appropriate frequency for aerobic exercise is 3-5 time per week and total workout time should be able 20-60 minute depending on the intensity of the activity. world health organization (2006)suggests that one should take at least 10,000 walking step counts per day for health promotion. in gonji preparatory school, male students particularly show high motivation to participate in physical education class, the time allocated for physical education period allocated is one period per week for 40 minute it might be limit them further progression and intensity of 10 11 exercise. this trend might be made students developing poor fitness levels against expected norms in each grade level. based on the period allocated for grade eleven students physical education class and its effectiveness on physical fitness variables of students the researcher conducted this research to fulfilled gap investigate the effect of twelve-week aerobic exercise training on selected health-related physical fitness variables of body composition, cardio-respiratory fitness, skeletal strength, and muscular endurance. finally, the researchers hypothesized an experimental group’s of body composition and cardio-respiratory fitness would have significant differences following exercise interventions compare with control groups. thus, this study was undertaken with the objective of investigating the effects of aerobic exercise training on selected health-related physical fitness parameters in gonji preparatory school grade eleven male students. materials and methods description of the study area the study was conducted at gonji preparatory school by involving grade eleven male students. gonji kolela woreda is located in west gojjam zone, amhara national regional state. the administrative center of west gojjam is finoteselam; it is also the administrative center of gonji kolela woreda, which lies 72 km south-east of baihr dar the amhara regional state capital. sampling method and strategy for this study, 242 grade eleven male students were selected purposively from the target east afr. j. biophys. comput. sci. (2022), vol. 3, issue 1, 9-16 population. based on inclusion criteria only 108 students fulfilled the criteria, of which 51 students declined to participate and 57 were volunteer to participate in the study. however, to manage the study properly, only 30 students were selected by simple random sampling technique from 57 volunteers. then the study subjects (n=30) were randomly assigned into equal experimental and control groups (n = 15) respectively. the age of these students assigned in the two groups (n = 30) ranges from 18 to 22 years. all students selected to participate in the study were with good health condition. study design and methodology exercise training protocol the necessary data were collected pre-test and post-test interventions from experimental and control groups. the training period lasted for 12-week.study participants were exercised for three nonconsecutive days per week i.e. monday, wednesday and friday morning for 40 60 minute, at 50-74% hr max moderate intensity. during each training session, six different exercises were performed in aerobic training; aerobic dance, walking, jogging, running, rope jumping and minor game of football. to control the intensity of the exercise, first the researcher calculated training heart rate of each student by using karvonen’s formula for aerobic using the maximum heart rate to calculate a training threshold and listed down on paper then counted their heart rate for 15 seconds between the training (costill et al., 2008). 12 east afr. j. biophys. comput. sci. (2022), vol. 3, issue 1, 9-16 procedure:-measured the student’s height in meters and weight in kilograms. scoring:-to determined bmi divided the weight by the height squared: bmi = weight / height2 (quetelet, 1835). data quality control to ensure the validity and reliability of the study, standardized testing procedures and measurement instruments were employed. standardized instruments designed for data collection were used to accurately measure study variables and to assess data collection validity. to ensure the uniformity, reliability, and consistency of measurements, each variable was measured three times on each participant, at the same time of day, and under similar environmental conditions. measurements were consistently scheduled at the same time throughout the testing period and were taken by the same examiner, following instrument calibration before each session. ethical consecrations the study procedures were approved by the research ethics review committee of hawassa university, college of natural and computational sciences (rerc/004/20), and written informed consent was obtained from the participants. the benefits of this research were highlighted to participants. they were assured that their participation in this study is voluntary, and that it is greatly appreciated. clear awareness was also given to all grade eleven male students that the choice not to be involved in this study was not affect their future career in any way. harvard step test step test was designed to measure cardiovascular fitness or endurance by using a 51 cm high bench or box watch for timing minute. the step test works on the rationale that individuals with a high level of cardiorespiratory fitness will have a lower heart rate during recovery from three minutes of standardized exercise than less conditioned individuals. the lower heart rate after the test will be an indicator of being fitter (brouha et al., 1943). procedure:-the test subject repeatedly steps onto and off of a platform in a cycle of two seconds. the height of the platform is 51 centimeters for men. the participant must maintain a stepping rate of 30 steps per minute for five minutes or until reaching exhaustion. a metronome is used to ensure the correct pace. exhaustion is defined as the inability to sustain the stepping rate for 15 seconds. upon completing the test, the participant immediately sits down, and heartbeats are recorded at intervals of 1 to 1.5 minutes, 2 to 2.5 minutes, and 3 to 3.5 minutes. scoring: the results were recorded as time until exhaustion in seconds (tc) and total heartbeats counted (hb). it is plotted into a simple fitness index equation: tcx100/hb x 2 (brouha et al., 1943). body mass index body mass index (bmi) is a calculation used to estimate body fat based on a person's height and weight, applicable to both men and women. the purpose of bmi is to determine the ideal body weight in relation to body fat and lean tissue. east afr. j. biophys. comput. sci. (2022), vol. 3, issue 1, 9-16 13 experimental group (eg) and control group (cg), respectively. these showed that the study participants’ characteristics were homogeneous groups. experimental and control groups data analyzed within-groups by paired t-test and betweengroup effects analyzed by independent t-test design were applied during pretest and post-test of exercise interventions’. experimental and control groups were participated in regular physical education programs aligned with the ministry of education school curriculum one period of 40-minute per week. in addition the experimental group engaged 12-week aerobic exercise training for 3 days per week for 40 up to 60 minutes per session. results the results of the study purpose at the effects of aerobic exercise on selected health-related physical fitness parameters in gonji preparatory school male students are summarized in table 1. . table1: paired t-test analysis result of the pre-test and post-test data of the experimental group and control group variables (n=30) group pre-test x̅± sd post-test x̅± sd t p bmi (kg/m2) experimental group 18.97±1.33 18.35±1.10 9.64 0.000* control group 19.77±1.12 19.81±1.14 1.72 0.107 harvard step test (30 steps/ minute) experimental group 104.53±12.55 118.27±12.55 -12.06 0.000* control group 104.13±11.45 103.67±12.41 -0.344 0.736 bmi: body mass index, *significant at p<0.05 level body mass index (bmi) and harvard step test pre-test and post-test data of control group revealed that (t=-1.72, p>0.05) and (t=-0.344, p>0.05) no statistical significant. on the other hand, experimental group in body mass index pre-test and post-test data (t = 9.64,p <0.05) and harvard step test (t =-12.06,p < 0.05) have been found statistical significant. each participant was allocated a number and alphabetical code to ensure that confidentiality and anonymity is maintained. information sheets, agreement and consent forms have been translated into the national language of ethiopian in amharic. all data will be kept in the possession of the principal research team, and will be destroyed five years after the completion of this study. data analysis the collected data were analyzed using statistical package software for social science (spss) version 20. paired t-test and independent t-test were used for data analysis. the level of significant was set at p<0.05. the characteristics of study participants mean and standard deviation (sd) of age (yr.), height (m), weight (kg) and maximum heart rate were 19.13±0.74, 1.69± 0.06, 54.39 ± 4.82 and 200.86±0.74, and 19.07±0.88, 1.68± 0.04, and 55.78±3.65 and 200.93±0.88 for the east afr. j. biophys. comput. sci. (2022), vol. 3, issue 1, 9-16 14 table -2: independent t-test analysis result of the pre-test and post-test data of the experimental group and control group variables (n=30) group pre-test x̅± sd post-test x̅± sd t p bmi (kg/m2) experimental group 18.97±1.33 18.35±1.10 -3.57 0.001 control group 18.78±1.12 19.81±1.14 -1.79 0.085 harvard step test (30 steps/ minute) experimental group 104.53±12.55 118.27±12.55 -4.26 0.000 control group 104.13±11.45 103.67±12.41 0.091 0.928 *significant at p<0.05 level as summarized in table 2, body mass index pretest and post-test data of the control group (t =1.79, p > 0.05) and harvard step test (t =0.091,p > 0.05) have been found no statistical significant. whereas, in the experimental group the pre-test and post-test body mass index data (t = -3.57, p<0.05) and harvard step test (t = 4.26, p < 0.05) have been found statistical significant. discussion in this study, a statistical significance reduction in bmi and harvard step test values has been determined for male students participated in 12 weeks aerobic workout. when pre-test and post-test values with-in groups experimental group were examined, the difference in the body mass index average before exercise (18.97±1.33) and after exercise (18.35±1.10) was statistically significant (p < 0.05). on the other hand, pre-test and post-test values with-in control group were examined, body mass index average before exercise (19.77±1.12) and after exercise (19.81±1.14) was not statistically significance (p > 0.05). these findings are comparable with the findings of arslan (2011) who investigated the effect of two exercise protocols (step-up and aerobic dance exercise) on body composition parameters after eight-week exercise. the study participants took part in a step-up and aerobic dance exercise programs for one hour per day, 3 days a week for 8 weeks. after the eight weeks of the step-up and aerobic dance exercise program, it was found that the decrease in the waist body mass index in exercise groups was significant. similarly, patricia (2008) tried to examine the effects of a 12-week exercise based training program on aerobic fitness and body composition. their study found that exercise training significantly improved body mass index of the exercise group, but on the contrary, the body weight of the control group increased significantly at the end of the 12week exercise intervention program period. based on the findings of the current study, in parallel with the literature, aerobic exercises program can result a positive effect in body fat percentage. following 12-week aerobic exercise training the difference in the harvard step test average before exercise (104.53 ± 12.55) and after exercise (118.27±12.55) in experimental group was statistically significant(p < 0.05). on the contrary, the difference in the harvard step test average before exercise (104.13±11.45) and after exercise (103.67±12.41) in the control group was not statistically significant (p > 0.05). in lie with this, williams and morton east afr. j. biophys. comput. sci. (2022), vol. 3, issue 1, 9-16 15 (1986)also conducted a 12-week aerobic dance exercise protocol. accordingly, significant improvements were observed in vo2 max, increased lean body mass and decreased body fat percentage following the 12 weeks exercise intervention. however, the difference of these parameters in the control group were not statistical significant. mahendran (2009) also conducted similar study on the effects of 12week aerobic exercises on selected healthrelated variables of body composition, cardiovascular endurance and muscular endurance. the exercise program protocols were walking, jogging, running and rope skipping at the end of exercise interventions a 12-minutes run test was given for the study participants. mahendran i his finding showed that statistical significant in body composition, cardiovascular endurance and muscular on the study participants of experimental group p < 0.05. were observed, but not on control group. it can be can conclude that walking, jogging, running and aerobic dance increase the performance of step test exercise according to the study findings which is parallel to the literature. conclusion based on the major finding of this study, it was conclude that 12-week aerobic exercise training program has significantly improved on student’s cardio-respiratory fitness and body composition on the study participants of experimental group. on the contrary, student’s participated in regular physical education class for 40-minute per week assigned as control group has no significant improvement on selected health related physical fitness components of cardiorespiratory fitness and body composition. so that, based on the findings indicated 40-minute physical education period may be limiting the students’ performance to improve health-related physical fitness components. therefore, it is better to revisit the period allocation of regular physical education practical class, i.e. the allocated, 40 minute per week for grade eleven curriculum needs modification to protect the student’s health through movement and enhance physically fit, mentally alert, emotional stable and socially interactive citizens. acknowledgements the authors wish to thank college of natural and computational sciences of hawassa university research ethics review committee (rerc) for permitting us ethical approval for implementation of this manuscript. references american college of sports medicine 2009.acsm guidelines for exercise testing and prescription 9th ed. lippincott williams & wilkins, philadelphia, 346 pp. arslan f. 2011. the effects of an eight-week stepaerobic dance exercise program on body composition parameters in middle-aged sedentary obese women. int. j. sports med..12(4):160-168. bharath m. and mukesh g. 2011.a comparative study of physical fitness of central, navodaya and adarsh residential schools’ students of gujarat state. asia j. phys. edu. comp, sci. 4(1):41-42. brouha l., heath c.w. and, graybiel a. 1943. step test simple method of measuring physical fitness for hard muscular work in adult men. rev. canadian biol. 86 (2). butler r.n., davis r., lewis c.b., nelson m.e. and strauss e. 1998.physical fitness benefits of exercising for the older patient. 3(10):46-62. california department of education 2009.reference guide, 2012–13 california physical fitness test.(http://www.cde.ca.gov/ci/cr/cf/document/, accessed on june 12, 2019). east afr. j. biophys. comput. sci. (2022), vol. 3, issue 1, 9-16 16 costill d. l., kenney w. l., & wilmore j. 2008.physiology of sport and exercise. human kinetics publisher, california.265 pp. hillman c. h., erickson k. i. and kramer a. f. 2008. be smart, exercise your heart: exercise effects on brain and cognition nat. neuro sci. 9 (1): 68 -76. lavall e.h., shepherd r.j. and volle m. 1984.an endurance fitness program in primary school children. community health studies. 3 (2): 4556 mahendran p. 2009.effect of 12 weeks aerobic exercises on selected health-related physical fitness and physiological variables of adolescents. unpublished msc thesis, pondicherry university, pondicherry.128 pp. patricia w. 2006.concepts of physical fitness. active lifestyles for wellness. 13thedition. new york: mcgraw-hill. quetelet a. 1835. a treatise on man and the development of his faculties. new york: rosser printing. rosser m. 2001.body fitness and exercises.2nd edition. new delhi. 342 pp. shahana a., usha s.n. and hasrani s.s. 2010. effect of aerobic exercise program on health related physical fitness components of middle aged women br. j. sports med. b 4 (4): 1923. thomas d., paul m. and walton t. 2004. fit & well: core concept and labs in physical fitness and wellness. california state university. mcgraw-hill companies.6th ed. 385 pp. williams l.d. and morton a.r. 1986.changes in selected cardio-respiratory responses to exercise and in body composition following a 12‐week aerobic dance program. j. sports sci. j. 4(3):189-199. world health organization (who) 2006. obesity and physical activity: the 2006 technical report series. woh, geneva, switzerland. . slide number 1 editorial board members table of contents slide number 6 volume 2.pdf cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 6 volume 2.pdf cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 slide number 1 editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 *corresponding author: email: annamercy2002@yahoo.co.in t.v. anna mercy*1, eapen jacob2 & k. raju thomas3 1kerala university of fisheries and ocean studies, panangad, cochin, 682506; 2dept. zoology, govt. college, kariyavattom, trivandrum.; 3dept. zoology, mar thoma college, thiruvalla, kerala, 689103 keywords: captive breeding; d. fasciata; puntius fasciata; ornamental fish; western ghats abstract ornamental fishes of the western ghats of india have great demand in the export market. at present these fishes are collected from the wild and exported. hence many times, the demand could not be met due to short supply. the only remedial measure for a sustainable supply is to produce the fish in captive conditions. unfortunately, the breeding technology for the ornamental fishes of the western ghats of india has not been attempted seriously till date. the present paper is almost a pioneering attempt to develop captive breeding technology for 12 prioritized species of the indigenous ornamental fishes of the western ghats of india. dravidia fasciata is one of them. it is popularly known as melon barb. it is a beautiful barb, growing to a maximum size of 80 mm. in the present paper the methodology of captive breeding of this fish is provided with the economics of its production. melon barbs were collected from the wild and brought to the hatchery of college of fisheries in oxygen filled plastic bags and gradually acclimatized to the captive conditions. its size at first maturity, sexual dimorphism, and developmental biology were studied and described with photographs. the total length (tl) at first maturity for males was 50 mm (50-55 mm) and 40 mm for females (40-45 mm). a sexually mature male developed beautiful pinkish red tinge all over the body. the black bands over the body also became deeper in colour during this time. the intensity of the colour reached its maximum during the courtship activities. male also possessed nuptial tubercles on the operculum which could be identified only by keen observation. but a sexually mature female did not develop any colour change by the onset of sexual maturity. the results of the study clearly demonstrated that d. fasciata could be successfully produced in captivity through scientific management of brooders, eggs, larvae and hatchlings. the successful development of captive breeding technology is likely to pave way towards commercialization of the technology thus leading to the sustainable export of the species. introduction kerala has rich sources of water bodies such as rivers, lakes, reservoirs, canals and ponds. the rivers of kerala possess rich diversity of ornamental fishes, with over 155 species of indigenous species (mercy et al., 2007). some of the potential ornamental fish of kerala namely loachs, barbs, danios, catfishes, perches and cichlids are in great demand in export market. at present, these fishes are collected from the wild and exported. even though kerala hawassa university college of natural & computational sciences year 2021 volume xx no xx 1 east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs captive breeding, developmental biology and commercial production of dravidia fasciataan indigenous ornamental fish of the western ghats of india east afr. j. biophys. comput. sci., vol. 2, issue.1, 1-13 research article mailto:annamercy2002@yahoo.co.in east afr. j. biophys. comput. sci., vol. 2, issue 1 is a goldmine of indigenous ornamental fishes, the quantity of export is minimal. there are several reasons for the low export of fishes. the most important reason is that the exporters are not able to supply as per the demand. the demand usually, is for equal sized fishes in large quantities which cannot be supplied from wild collection alone. this can be achieved only through hatchery production. hence, breeding in captivity is one of the desirable qualities of any ornamental fish. unfortunately, the breeding technology for the ornamental fishes of the western ghats of india has not been attempted seriously till date, except for the work done by mercy (2004) in which captive breeding technology was developed for 12 prioritized species of fishes. d. fasciata is one of them. dravidia fasciata is a beautiful indigenous ornamental fish found in the west flowing rivers of goa, karnataka, kerala and up to kanyakumari district in tamil nadu and also in the east flowing streams of river cauvery basin in the foot of the nallamala hills (jayaram, 1991). it is popularly known as melon barb. it is a small barb that grows to a maximum size of 8cm. it is omnivorous in diet and also is eaten by larger fish and crustaceans (mercy et al., 2001). captive studies on the behavior of the fish under aquarium conditions have shown that it occupies the mid water column in the tank. present paper describes the captive breeding technology of this beautiful ornamental fish. the development of captive breeding technology of this species clearly indicates that commercial production of d. fasciata is possible with this technology through scientific management of brooders, eggs, larvae and hatchlings. this success is likely to pave way towards commercial production of this species thus leading to its sustainable export. materials and methods specimens of d. fasciata were collected from river pampa using cast net and small hand nets during the months of august-september (200205). they were brought to the hatchery of college of fisheries in oxygen filled plastic bags and gradually acclimatized to the captive conditions. determination of size at first maturity and identification of male and female are two essential requirements for breeding a fish under captivity. size at first maturity the length at which 50% of the fishes become mature is considered as the size at first maturity (kagwade, 1975). size at first maturity was computed with a total of 154 fishes of which 83 were females (ranging from 25 mm to 60 mm total length (tl)) and 71 were males (ranging from 30 mm to 65 mm tl). the total length of all the fishes collected was grouped according to different length groups. the percentage occurrences of mature fishes (early ripening, late ripening, ripe and partially spent) for both females and males were calculated. by plotting the percentage occurrence of mature fish (males and females) against respective length classes (5mm), the length at which 50% of the fishes become mature was demarcated. sexual dimorphism different macroscopic and visual features were used for determining the sex of the individual. these includes 1) overall body coloration (sexual dichromatism); 2) bulginess of the stomach and 3) behaviour in captive conditions 2 east afr. j. biophys. comput. sci., vol. 2, issue 1 a total of 55 specimens were used for sex determination studies and they included fishes collected from their natural habitats and f1 and f2 generations of the hatchery reared fish. different nuptial and breeding behavioral gestures like chasing; following, nubbing etc. also were used for distinguishing the sexes. development of brood stock the brood stocks were raised on a mixed diet of artificial pelleted feed, live feeds like moina, mosquito larvae, blood worm and egg yolk. they were kept in glass tanks fitted with biological filter and in cement tanks devoid of biological filter. a daily water exchange at a rate of 1/3 was ensured in the cement tanks. they were continuously observed for their behavior in tanks. the maturity condition of the brooders was assessed based on the macroscopic characters such as body size, bulginess of belly and overall body colouration. sometimes the behavioral patterns of the fishes were also considered. as the specimens became sexually mature they were separated sex-wise and kept in separate tanks of the same dimensions mentioned above. captive breeding breeding was conducted in small cement cisterns or round cement tanks as shown in the photographs (plate ). a breeding tank was set up providing the same water quality available in the natural habitat of the fish. the tank was cleaned properly and filled with water of desired quality up to three fourth of the tank. a separating net with small mesh mounted on a ring was kept 30cm above from bottom of the tank so that the eggs laid are fallen through the net to bottom of the tank this prevented the parents from devouring it. a pair of wellconditioned, fully mature melon barb (1:1 male: female) was introduced to the prepared breeding tank on an evening and were observed for their breeding. next day morning eggs could be seen under the net trap in the tank. a total of 10 pair was used in each trial. the latency period was observed as the time duration between their introduction of conditioned pairs into the experimental tank and the start of spawning. soon after the completion of laying eggs the fishes were removed from the breeding tank and the eggs were counted to find out the fecundity. the counting was conducted using the random sampling method. developmental biology the fertilized eggs were collected soon after it was spawned. from each pair 5 to 10 eggs were collected and placed them in 2 liter capacity container. developing eggs were observed with a trinocular microscope (labomed) and photographs were taken with slr camera (nikon 90 x). the early developments up to hatching of the eggs were done in one hour interval. after hatching the developmental stages were photographed every 2 hours up to 24 hours and thereafter at every 24 hours up to the juvenile stage. all the measurements were taken under average room temperature of 26 to28 °c. the eggs were placed in cavity slides, immersed in water for observations and cavity blocks were used to observe larvae after hatching. the sampled eggs and larvae were fixed in 4% formalin for further observations. in the present study, the developmental stages were divided into embryonic development, larval development and post larval development. the embryonic development started inside the 3 east afr. j. biophys. comput. sci., vol. 2, issue 1 chorion and completed at hatching. the larval stage started from hatching and ended by the appearance of fin rays in all fins. after that, the larva was transformed into post larvae. the development of 25 individual embryos was documented right from fertilization. the water quality parameters were monitored weekly and daily exchange of 25% of water was done. results and discussion size at first maturity the total length (tl) at first maturity was determined by analyzing the data relevant to all mature fishes (stage iii and above examined). while the first mature male fishes appeared in 45-50 mm (tl) group (16.66 %), the first mature females appeared only in the group of 30-35 mm (16.66 %). all male fishes were matured on reaching a total length of 55 mm and all female fishes on reaching a length of 50 mm total length. the size at first maturity for males was 50 mm tl (50-55 mm) and for female it was 40 mm tl (40-45 mm) (figure 1). figure 1. size or total length of dravidia fasciata at first maturity the smallest mature male is within 40-45 mm length group. if the length at which 50% of the fishes are mature can be considered as the minimum length at first maturity (kagwade, 1975), the specimens below 40 mm tl for males and 30 mm tl for females were not mature. the present study showed that the smallest mature male is bigger than that of the mature female in d. fasciata. mercy et al. (2005) reported the size at first maturity of puntius melanostigma as 50 mm for males and 55 mm for females. in the case of the african minnow, enteromius paludinosus, sexual maturity was reached within a year at 50.0 mm tl (cambray and burton, 1985). in the case of european minnow, phoxinus phoxinus the short lived populations of river frome in england contained two spawning age groups and the largest fish caught was only 78.0 mm long. the size at first maturity ranged from 50-55 mm as two year olds (mills, 1987). six barbus species studied in sri lanka had maximum total length of between 42.0 and 101.0 mm and a short life span (de silva et al.,1985). in the freshwaters of south africa out of the 52 barbus species studied 43 attained maximum fork lengths of less than 150.0 mm (cambray and burton, 1985). the information on initial sexual maturity gives the ornamental fish producers the idea on the age at which the fish become mature 4 east afr. j. biophys. comput. sci., vol. 2, issue 1 so that they could provide appropriate environment for the fish to spawn and obtain the maximum number of fry. sexual dimorphism the male and female dravidia fasciata showed clear differences in body coloration which could be termed as sexual dichromatism. the colour differences become prominent at the onset of sexual maturity. all the immature fish appeared in a dull grayish silvery colour. a sexually mature male developed beautiful pinkish red tinge all over the body (figure 2). the black bands over the body also became deeper in colour during this time. the intensity of the colour reached its maximum during the courtship activities. but a sexually mature female did not develop any colour change by the onset of sexual maturity. it remained in the same colour pattern as that of a juvenile. male also possessed nuptial tubercles on the operculum which could be identified only by keen observation. these types of nuptial tubercles are distinguishable in other cyprinids like gold fish, carassius auratus and indian major carps which have tubercles on pectoral fin rays also. another distinguishing character was the bulginess of stomach. a sexually mature female dravidia fasciata exhibited a more swollen and deeper stomach than that of the males. the reproductive behavioural patterns exhibited during the onset of maturity were also used to distinguish sexes. dravidia fasciata male dravidia fasciata female figure 2. sexual dichromatism of dravidia fasciata in cyprinids, sexual dimorphism in morphological characteristics other than colouration or presence of nuptial tubercles is uncommon (scott and crossman, 1973). sexual dimorphism is a widespread phenomenon in fishes and may occur for a variety of reasons including, mate selection, male to male competition for mates, differences in sexual roles, predator avoidance, territoriality and ecological processes (hubbs et al., 1974; fernandes, 1998). sexual dimorphism in body size, coloration, fin length, nuptial tubercles, and intromittent organs has been observed in many fish families (scott and crossman, 1973). sex identification has practical applications in captive propagation processes. males and females usually differ not only in 5 east afr. j. biophys. comput. sci., vol. 2, issue 1 reproductive organs, but also in external structures that are not directly related to reproduction. information about sexual dimorphism is required for understanding the ecology, behavior and life history of a species. in addition, knowledge of sexual dimorphism and its appearance during ontogeny is indispensable when making morphological comparisons between populations. although sexual differences in a variety of external structures have been noted in many species, studies on the sexual difference in fresh water fishes of india are less. a comprehensive study was done by inasu (2008) in which sexual dimorphism of 26 species of indian fishes was compiled. mercy (2004) and mercy et al. (2001, 2002, 2007, 2013) have described the sexual dimorphism of danio malabaricus, pristolepis marginata, puntius melanostigma, garra mullya, puntius pookodensis, nemacheilus triangularis and puntius denisonii, which are important freshwater ornamental fishes of the western ghats of india. dravidia fasciata exhibited sexual dichromatism rather than sexual dimorphism. breeding adults of male d. fasciata had marked sexual dichromatism. males became pinkish when they became sexually mature. reproductive females did not have pink colour. the colour became intense after the fish started breeding. it gradually faded after the courtship. this suggests that sexual dichromatism in the body is a secondary sexual character that may be regulated by reproductive hormones. although sex in d. fasciata is genetically determined, it is currently unknown what genes or hormones might regulate secondary sexual dichromatism of body in this fish. further analysis of the genetic and developmental mechanisms that underlie sexual dimorphism in d. fasciata will be possible by using the genomic tools established by peichel et al. (2001) and peichel (2005) and will provide a complement to ecological studies to discern the functional significance of sexual dichromtism in d. fasciata. similar type of secondary sexual characters were also observedin p. melanostigma (mercy et al., 2004) and p. pookodensis (eapen, 2013). captive breeding the fully mature and well-conditioned male and female fishes were introduced in the prepared experimental tank (plate) at a sex ratio of 1:1 (female: male). soon after introduction, the fishes did not show any indication of breeding behavior. after half an hour, the fishes started its breeding behavioral signs like chasing, nubbing, following etc. breeding behaviour parental care of the eggs and hatchlings either by male or by female parent was not observed in d. fasciata. it agrees with general behaviour of the cyprinid fishes. in the case of d. fasciata, it not only showed any signs of parental care but it also showed the tendency to deavour the eggs and hatchlings. so an appropriate breeding trap was needed in the captive breeding set up to protect them from the hungry parents. all cyprinids spawn using egg scattering methods and do not usually exercise parental care. but an exception is reported in fathead minnow pimephales promelas (sargent, 1989). the number of eggs spawned was at a range of 180 to 415 with a mean 264±86.6. the survival rate was at the range of 49 to 68%, with a mean 55.16±2.7. 6 east afr. j. biophys. comput. sci., vol. 2, issue 1 developmental biology embryonic development immediately after fertilization the eggs were swollen up considerably by absorbing water and within five minutes they attained a spherical, transparent and slightly adhesive structure. a streaming movement of the egg protoplasm took place, which resulted in the formation of blastodisc. the fertilized eggs of d. fasciata were amber coloured en mass, yolked, glossy, translucent and spherical with an average diameter of 0.85 mm (0.85 ± 0.02 mm). like most other cyprinids the eggs of d. fasciata were free and demersal but not adhesive. the location of the micropylar region was distinct as a small depression in the animal pole, while it was absent in unfertilized eggs. the yolk which often had a yellowish tinge was coarsely granulated. the eggs were easily collected and transferred for incubation in hatching tanks with continuous oxygenation. the observations revealed that the hatching of eggs was accomplished 23 to 27 hrs in the ambient temperature of 26 °c (26 ± 2°c). neutral ph was maintained for the medium throughout the studies. after observations, some of the eggs were preserved in 5 % formalin for future studies. all measurements were made on fresh specimens using a calibrated ocular micrometer. photographs of the developmental stages are provided in plate (annex). the fertilized egg was telolecithal and cleavage was meroblastic. the blastoderm formed was restricted to animal pole at the point of entrance of sperm at the level of the micropyle, leaving large yolk mass at the vegetal pole. the first cleavage was meridional and incomplete. the second division was at perpendicular to the first and the third division resulted in the formation of 8 cells. the 4th cleavage resulted in the formation of sixteen celled stage at 1.3 hrs and formation 32 celled stage occurred at about 1.45 hrs. a clear blastocoel began to appear at about 3.3 hrs and the blastula at this stage appeared as a cap of cells over the yolk. by 5 hrs it started to roll over the cytoplasm. after 5.5 hr, the blastoderm covered more than half of the yolk surface. at about 6.5 hours the early gastrula stage was reached and an embryonic shield was appeared. gradually, epibolic germ layers were spread to the equator of the spherical yolk surface and at 6 hrs, the germ ring invaded 3/4th of the yolk surface. at 7.5 hrs, the neural plate was formed and gradually almost 5/6th of the yolk surfaces become invaded. as the blastopore got closed, yolk plug was projected and the head rudiment was seen lifted up. by 10 hrs, the optic rudiment appeared and gradually by 10.5hrs it became differentiated into a vesicle. at this stage, the head and tail got differentiated and the myotomes also became clearly visible. at 12 hrs the tail bud was formed and the embryo appeared very much elongated and was seen encircling over the yolk, reaching nearly 3/4th of its circumference. at 15 hrs, caudal fin fold rudiment was drawn out from the yolk and the head region became more and more differentiated. yolk sac got stretched and assumed a characteristic beaked appearance. tail bud was projected out from the beak like yolk mass distally at around 16 hrs. paired somites also became distinct at this point of time. at 18 hrs, optic vesicle became 7 east afr. j. biophys. comput. sci., vol. 2, issue 1 conspicuous and the head region got separated; the caudal fin fold became very much elongated and the embryo appeared ‘c’ shaped encircling the yolk. at this period, the muscular somites were seen twitching at intervals. at 21 hrs the heart and optic capsule became conspicuous and embryonic movement became rapid. the heart began to pulsate at 21.5 h. at 22 hrs, tail got free and encircled almost 90 percent of the yolk mass. gradually the heart pulsation became more rhythmic. the embryo began to roll within the egg case. as the development advanced, the embryo appeared more and more elongated and the tail overlapped the head. the myotomes and auditory vesicle became more prominent and the twitching of embryo started within the cytoplasm. as time passed the twitching movement of the embryo became faster. close to hatching, twitching and lashing of embryo inside the egg capsule became rapid. the egg shell was broken up and the tail emerged out first, followed by the head region. hatching occurred at around 23.5 hrs. egg hatching was protracted and the incubation period fluctuated between 23and 27 hrs post fertilization at the ambient temperature. newly hatched larva the newly hatched larva appeared to be sluggish and remained at the bottom. it was transparent without any pigmentation. a continuous fin fold was present starting from the start of the dorsal fin, surrounding the tail and ended in the insertion of the ventral fin. oral and anal orifices were completely absent. the length of the hatchling at this stage was 2.3 mm. in 24 hours it attained a mean length of 16 mm. melanophores started to appear on the opticrim and myotomes. at 48 hours, the larva appeared slender and elongated. the yolk was very much reduced, though not completely exhausted. the hatchlings gradually began to swim up towards the water surface and sometimes found hung up from the water surface. melanophores became conspicuous on the body surface. fin rays were started to appear in the pelvic fin and stomach was visible through the transparent body. above the stomach the gas bladder appeared as a glittering droplet. a small depression was started to appear on the fin fold at the portion of anus. juvenile phase: one month old juvenile (average 25.80 ±1.39 mm tl) of d. fasciata (originally puntius) showed vertical body banding pattern. many species of puntius possessed black body markings at their juvenile phase which were quite different in size and shape. the juveniles of d. fasciata possessed three vertical black cross bands at nuchal, pre dorsal and caudal positions. details of embryonic developmental stages are given in table 1 8 east afr. j. biophys. comput. sci., vol. 2, issue 1 table 1the embryonic developmental stages of dravidia fasciata time after fertilization (hours) developmental event 01.30 16 celled stage 01.45 32 celled stage 02.00 early morula 03.30 blastulation; blastodisc formation 06.50 gastrulation; early gastrula 07.00 late gastrula 07.50 neurula stage 08.00 closure of blastopore/ yolk plug 10.00 optic rudiment appears 12.00 formation of head and tail, appearance of myotomes 16.00 tail region detaches from the yolk 21.00 twitching 22.30 heart beat and blood flow starts 23.00 – 24.00 hatching the knowledge on different embryonic stages and its timings of developmental events has importance in developing hatchery techniques of a species. as far as d. fasciata is concerned, because of its importance in the ornamental fish trade, defining an effective hatchery technique is tremendously valued. in general, developmental biology of a species consisted of embryonic, larval and juvenile stages. the morphology of larval and juvenile d. fasciata viz., overall appearance, fin ray formation, and pigmentation patterns were similar to that of many other cyprinids such as puntius pookodensis (jacob, 2013) and also as reported by jones (1938); balinisky (1948) and mcclure (1999). it is also to be noted that d. fasciata, puntius filamentosus and puntius denisonii co-exist and breed in the same habitat at the same season and the larvae of all the three species look alike with dark bands across the body. it is quite difficult to distinguish between the larvae unless experienced. in the case of p. filamentosus and p. denisonii the cross-bands are retained for about one month. they gradually fade to a single spot at the caudal peduncle in the case of p. filamentosus whereas they are completely vanished in p.denisonii (mercy et al., 2013). dry-season spawning of d. fasciata has already been observed and published by harikumar et al. (1994). in the present study it has been observed that the peak period of breeding of d. fasciata is during the months from november to march/april. de silva et al. (1985) have reported that among puntius species in srilanka seasonal and perennial breeders share the same macrohabitat. survival rate number of eggs produced at a time ranged from 30-40 eggs per gram bodyweight. average weight of the female fish was 10-12gms. about 9 east afr. j. biophys. comput. sci., vol. 2, issue 1 90 % of the eggs were fertilized and at the end of one month survival rate was 60-65%. on an average from a pair of brood 180-200 young ones can be obtained if properly maintained. the economics of production: the cost of production is summarized in the following table. fixed cost in us$ cement tanks: 12 x $ 30 $ 360 net + accessories $ 15 operational cost brood fish, 20 pair :20x$ 2 $ 40 feed+ accessories $ 50 packing and sale $ 15 total expenditure $ 480 income : from a single brood minimum number of 150 fishes can be obtained after three months. so from 20 pairs 3000 melon barbs can be obtained on an average sale of fish 3000x$0.5/ $1500 reproductive strategy studies on different aspects of captive breeding revealed that d. fasciata is an asynchronous spawner i.e., continuous development and release of gametes in the gonads are evident. the fish did not show any affinity towards aquatic plants or the presence of plants did not have any stimulating effect to start the spawning activities. in general, the reproductive strategies of d. fasciata showed that it is an iteroparous species, i.e., they spawn more than once during their lives and gonochoristic, i.e., their sexes were separate and exhibited external fertilization without parental care. the fish possessed an asynchronous type ovary i.e., oocytes of all stages of development are present without dominant populations. but the peak breeding time of the fish is during the period from november to march. d. fasciata can be bred continuously if proper conditions are provided, but the peak season is during the months of november–march/april. the species could be categorized as a batch spawner i.e., eggs are recruited and ovulated from the population of yolked oocytes in several batches over a protracted period during spawning season. a summary of reproductive strategies shown by d. fasciata is shown in table 2. 10 east afr. j. biophys. comput. sci., vol. 2, issue 1 table2: summary of reproductive strategies based on different components of breeding systems in dravidia fasciata sl. no. component of breeding system reproductive strategy 1 number of breeding opportunities iteroparous (multiple breeding) 2 type of spawning batch spawner 3 mating system promiscuous (both sexes with multiple partners during breeding season) 4 gender system gonochoristic 5 secondary sexual characteristics sexually dichromatic 6 spawning site preparation no preparation 7 place of fertilization external 8 embryonic development oviparity 9 parental care no parental care 10 ecological group pelagophils 11 reproductive guild (balon1975) ecological classification: non-guarders ethological classification: open substratum spawners morphotype :pelagophils conclusion the results of the study clearly demonstrated that d. fasciata could be successfully produced in captivity through scientific management of brooders, eggs, larvae and hatchlings. the successful development of captive breeding technology is likely to pave way towards commercialization of the technology thus leading to the sustainable export of the species as well as its conservation. acknowledgements the authors are thankful to national agricultural technology programme and indian council of agricultural research (icarnatp) and national bureau of fish genetic resources (nbfgr), lucknow for the funding and dean, college of fisheries, kerala agricultural university for providing facilities. references balinisky i. 1948. on the development of specific characters in cyprinid fishes. proceedings of the zoological society, london 118: 335-344. balon e.k. 1975. reproductive guilds in fishes: a proposal and definition. journal of fisheries research board canada 32: 821-864 cambray j.a. and burton m.n. 1985. age and growth of a colonizing minnow, barbus anoplus, in a manmade lake in south africa. environ. biol. fishes 22: 15-27. de silva s.s., schut j. and kortmluder k. 1985. reproductive biology of six barbus species indigenous to sri lanka. environ. biol. fishes 12:201-218. 11 east afr. j. biophys. comput. sci., vol. 2, issue 1 fernandes c.c. 1998. sex related morphological variation in two species of (gymnotiformes) from the amazone river basin. copeia 730-735. harikumar s., padmanabhan k.g., john p.a. and kortmulder k. 1994. dry season spawning in a cyprinid fish of southern india. environ. biol. fishes 39:129-136. hubbs c.l., miller r.r. and hubbs c. 1974. hydrographic history and relict fishes of the north central great basin. california academy of sciences of san francisco. inasu n.d. 2008. a check list of male female differences of some indigenous ornamental fishes. cochin university of science and technology, kochi. 65pp. jacob e. 2013. studies on the captive breeding and reproductive biology of two indigenous ornamental fishes of the western ghats. ph. d thesis. mahatma gandhi university, kottayam, india. jayaram k.c. 1991. revision of the genus puntius (hamilton) from the indian region (pisces: cypriniformes: cyprinidae). records of the zoological survey of india 135: 1-178. jones, s. 1938. on the breeding habits and development of a cyprinid, danio malabaricus (jordan) in ceylon. ceylon j. sci. (c) 4: 79-89. kagwade v.n. 1968. maturation and spawning in the horse mackerel, caranx kalla (cuv. and val.). indian j.fish. 15: 207-220. mcclure m. 1999. development and evolution of melanophore patterns in fishes of the genus danio teleostei: cyprinidae). j. morphol. 241: 83-105 mercy t.v.a., raju thomas k. and eapen j. 2001. food and feeding habits of puntius melananmpyx (day)an endemic ornamental fish of western ghats. in: proceedings of national seminar on ‘riverine reservoir fisheries of indiachallenges and strategies.’23-24 may 2001 ed. by society of fishery technologists, cift, cochin. mercy t.v.a., eapen j. and raju thomas k. 2001. breeding of danio malabaricusa potential indigenous ornamental fish of the western ghats in captive conditions .in: proceedings of national seminar on ‘riverine and reservoir fisheries of india-challenges and strategies’.23-24 may 2001. society of fishery technologists, cift, cochin. mercy t.v.a., jacob j. and raju thomas k. 2002. studies on the reproductive behaviour of the common catopra, pristolepis marginata jerdon (nandidae-perciformes) under captive conditions. curr. sci. 84 (11): 1468-1473. mercy t. v.a. 2004. status of standardized breeding and propagation technology of indigenous ornamental fishes of the western ghats of india. j. world aquacult. 35 (4):40-42. mercy t.v.a., eapen j. and raju thomas k. 2005. certain aspects of reproduction of puntius melanostigma, an endemic and endangered ornamental fish of the western ghats of india., p.644-648.“sustain fish”proceedings of the international symposium on improved sustainability of fish production systems and appropriate technologies for utilization, 16-18 march 2005. school of industrial fisheries, cochin university of science and technology, cochin, india. mercy t.v.a., gopalakrishnan a., kapoor d. and lakra w.s. 2007. ornamental fishes of the western ghats of india: national bureau fish genetic resources, lucknow.235 pp. mercy t.v.a., malika v. and sajan s. 2013. reproductive biology of puntius denisonii (day 1865) -an endemic ornamental cyprinid of the western ghats of india. indian j. fish. 60(2): 73-78 mills c.a. 1987. the life history of the minnow phoxinus phoxinus in a productive stream. freshw. biol. 17: 53-67. munshi d.t.s. and hughes g. m. 1992. air breathing fishes of india. oxfordand ibh pub. co. pvt ltd. newdelhi.181-208pp. scott w.b. and crossman e.j. 1973. fresh water fishes of canada. bull. fisheries research board of canada, ottawa, on, canada. peichel c.l. 2005. fishing for the secrets of vertebrate evolution in three spine sticklebacks. dev. dyn. 234:739-752. peichel c.l., ross j.a., matson c.k., dickson m., grimwood j., schmutzz j., myers r.m., mori s., schluter d. and kingsley d.m. 2004. the master sex-determination locus in three spine stickle backs is on a nascent y chromosome. curr. biol. 14: 14161424. sargent r.c. 1989. allopaternal care in the fathead minnow, pimephales promelas: stepfathers discriminate against their adopted eggs. behav. ecol. sociobiol. 25 (6): 379-385. 12 http://link.springer.com/journal/265 http://link.springer.com/journal/265 http://link.springer.com/journal/265/25/6/page/1 east afr. j. biophys. comput. sci., vol. 2, issue 1 plate: developmental stages of dravidia fasciata single celled stage two celled stage four celled stage blastula stage after four hours after 10 hours after 12 hours juveniles breeding tank breeding tank just hatched larva 24 hours after hatching 48 hours after hatching 13 all articles vol 2.pdf (p.6-81) volume 2 issue 1_ 6 articles_4_3.pdf (p.6-91) 4_captive fish_anna results and discussion references introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction *corresponding author: email: twesigyeck@yahoo.com; phone: +256782353775 biodiversity conservation and threat reduction in kibale and queen elizabeth conservation areas, uganda joseph katswera, norah m. mutekanga and charles k. twesigye* department of biological sciences, faculty of science, kyambogo university, p.o. box 1 kyambogo, kampala, uganda keywords: biodiversity; conservation; protected area; threats; wildlife introduction protected areas harbour a particularly rich and unique biodiversity (gibson et al.,2011; tranquilli et al., 2014). however, their existence is challenged by many interrelated anthropogenic activities that have intensified over recent decades (laurance, 1999; sodhi et al., 2007; wittemyer et al., 2008; tranquilli et al., 2014). increased human population growth journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx east afr. j. biophys. comput. sci., vol. 1, issue. 1 1 east african journal of biophysical and computational sciences research article this paper examines threats affecting the wildlife conservation areas, threat reduction and adaptive management strategies that enhance biodiversity conservation. the research was conducted through a survey, and data was collected from august 2018 to april 2019 in kibale and queen elizabeth conservation areas using literature review, threat reduction assessment technique, key informant interviews and focused group discussions and semi-structured questionnaires. the data was analysed using geographical information system software esri arcgis version 10.31, threat reduction assessment tool, pearson chi square test, spearman’s rho correlation coefficient, paired samples t-test, and oneway analysis of variables. the study established that staff education level and experience in conservation work influences biodiversity conservation. the conservation areas are threatened by habitat transition/changes, wild fires, human-wildlife conflicts, armed poaching and illegal wildlife trade/trafficking in game meat and game products, increasing human population pressure, and boundary encroachment. despite these threats, there was a general increase in large mammal population over the past decades, which collaborates well with the threat reduction assessment indices. both conservation areas had an ecological integrity rating average score of “yellow” indicating significant “concern” and therefore “dissatisfactory”. the two conservation areas are majorly threatened by anthropogenic threats, natural threats, and administrative constraints. the wildlife agency should integrate ecosystem health into the conservation agenda. the agency should also strengthen adaptive management, law enforcement, and collaboration with local communities and other stakeholders to reduce on the threats. finally, further research should focus on ecosystem health, and also the impact of tourism infrastructural development on biodiversity conservation. abstract mailto:twesigyeck@yahoo.com east afr. j. biophys. comput. sci., vol. 1, no. 1 has promoted the rapid expansion of threats to wildlife, habitat destruction through agriculture and unsustainable hunting of wildlife. biodiversity is the wealth of all life forms found on earth and encompasses all species of plants, animals, microorganisms, the ecosystems and ecological processes. moral justification and value to human existence are two major reasons for conserving biodiversity (christ et al., 2003). however, renewable natural resources are being utilized by humans at a rate exceeding their natural abilities to renew themselves (christ et al., 2003). human encroachment into natural ecosystems is increasing drastically throughout the world. forests are being exploited and cleared, farmlands have increased in extent, demand for grazing areas is on the rise and unregulated harvesting of the wild resources is becoming uncontrollable. as human activities exert pressure on the global environment, biological diversity declines, habitats are transformed and the population of some species dwindles to the point of extinction (whitmore and sayer, 1992). since man is constantly at variance with nature, the ever increasing human population coupled with technological development place stress on the environment and the world’s natural resources hence the unprecedented rate of biodiversity disappearance. threats to biodiversity in africa have led to the creation of numerous protected areas (pas), which are intended to conserve both fauna and flora, whilst benefitting neighbouring human communities. nevertheless, human populations throughout africa have increased the amount of pressure being exerted on pas. thus, despite their legal protected status, pas face significant threats(tranquilli et al., 2014). the most concerns are overexploitation of natural resources, habitat loss, fragmentation and isolation (wittemyer, 2008; laurance, 2012). these factors impact severely on key species and especially taxa with large body sizes, slow reproductive rates, and little behavioural adaptability (dimarco, 2014). protected areas (pas) are a cornerstone of biodiversity conservation efforts, as they provide various species with safe havens (radeloff et al., 2010). protected areas now cover more than 14.7% of the terrestrial land surface (unep-wcmc, iucn, 2016). recent syntheses suggest that pas are performing better than the broader landscape (barnes et al., 2016; gray et al., 2016), although numerous studies suggest that biodiversity continues to decline within many pas (craigie et al., 2010; laurance et al., 2012; geldmann et al., 2013). a principal objective of pas is to conserve nature by eliminating or reducing human pressures and threats operating within their boundaries. in addition to preserving biodiversity, pas should maintain natural processes and promote survival of species by excluding threats (margules & pressey, 2000). to achieve these goals, we must understand what the main threats are, where the potential threats occur, and where high-risk areas are distributed. identifying these threats is therefore crucial for conservation managers to take effective measures to mitigate some of the proximate threats to pas (wilson et al., 2005). knowledge of the occurrence and severity of threats to pas has largely been informed by remote sensing data (geldmann et al., 2014), modeling (hole et al., 2009), as well as questionnaire surveys with an emphasis on tropical regions (bruner et al., 2001; leverington et al., 2010; laurance et al., 2012). freely available satellite data offer global and 2 east afr. j. biophys. comput. sci., vol. 1, no. 1 standardized metrics form measuring those threats to pas that can be observed remotely, such as deforestation (joppa and pfaff, 2011) and fires (nelson and chomitz, 2011). however, many other threats, including some of the most frequently reported threats to species, according to the international union for conservation of nature (iucn) red list (e.g., overexploitation of species, invasive alien species, pollution, climate change), cannot be measured from space (joppa et al., 2016) and require field-collected data (mwangi et al., 2010). in uganda, however, little research has been done on the level of threats affecting biodiversity, their consequent impacts in protecting ecological integrity, and therefore, little documentation on the recommendations to mitigate biodiversity threats. therefore, the main aim of this study was to document the threats affecting the protected areas and propose adaptive management strategies to biodiversity conservation. the specific objectives were to (i) identify threats to biodiversity in the case study conservation areas, (ii) generate the threat reduction assessment (tra) index for each pa; and (iii) identify management measures employed by the parks that enhance effectiveness and efficiency in addressing threats. overall, this study presents tools for pa managers to make effective conservation and restoration decisions and consequently an important influence on global biodiversity conservation. materials and methods selection of the conservation areas for the study this study was carried out in the national parks and wildlife reserves within kibale and queen elizabeth conservation areas because their general management plans only highlight the different management challenges that affect the integrity of the protected areas without specifying the threat levels (uwa, 2012, 2015), and also for logistical reasons. based on knowledge of national parks and wildlife reserves in uganda, purposive sampling (babbie and benaquisto, 2002) was used to select the two conservation areas. specifically, the national parks and wildlife reserves included in this study were: kibale national park (795 km2), semuliki national park (220 km2), torosemliki wildlife reserve (542 km 2 ) and katonga wildlife reserve (207 km2) in kibale conservation area; and queen elizabeth national park (1978 km 2 ), rwenzori national park (995 km 2. ), kyambura wildlife reserve (157 km2) and kigezi wildlife reserve (330 km2) in queen elizabeth conservation area (fig.1) 3 fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the sample size and sampling technique the sample size of the respondents used during the study was determined using the method adopted from krejcie and morgan ( 1970) the study adopted stratified and purposive sampling technique to collect focused information. a total of 287 questionnaires were administered, and these were segregated as 208 individuals from households in the communities adjacent the case study wildlife protected areas, 53 to park staff, 4 to ecological experts, 16 to representatives of local authorities, 2 to uganda wildlife authority headquarters, 2 to wildlife conservation society-uganda, and 2 to the ministry of tourism, wildlife and antiquities. data collection the data and information used to determine the threats to conservation and how they were being addressed was collected from august 2018 to april 2019. permission to conduct the study was 4 east afr. j. biophys. comput. sci., vol. 1, no. 1 obtained from uganda wildlife authority prior to the start of the survey. in-depth interviews with 53 randomly selected resident park staff in the four national parks and four wildlife reserves of kibale and queen elizabeth conservation areas was carried out. eight focused group discussions (fgds), one per protected area, were made to collect data on the existing threats and identify management options to address them. each fgd had 5 to 8 park staff. four ecological experts who had conducted and or supervised various studies in the case study protected areas were interviewed to get expert judgment on the ecological integrity indicators. key informant interviews (kii) with two representatives (district political head and district environment/natural resources head) from each of the eight selected district local governments neighboring the parks and wildlife reserves; and six national level representatives mainly from uganda wildlife authority, wildlife conservation societyuganda, and ministry of tourism, wildlife and antiquities to gather more information. semistructured questionnaire were administered to 208 randomly selected community respondents living adjacent the parks and wildlife reserves. in addition, literature review to identify relevant existing information on the national parks and wildlife reserves pertaining wildlife conservation was also done. this data collection was guided by semi structured questionnaire that generated both qualitative and quantitative responses. both primary and secondary data were collected. specifically, data were obtained directly from the park staff, and existing literature including park reports, general management plans and annual operation plans, annual reports, field monitoring reports and routine reports. the threats to habitat integrity, quality and ecosystem functioning were identified. data analysis staff at each park and wildlife reserve headquarters were interviewed and gps points were collected using garmin etrex gps. these collected points in form of latitudes and longitudes were downloaded, entered in msexcel, converted to decimal degrees and exported to geographical information system (gis) software esri arcgis version 10.31 for map production. responses from the park staff were analyzed using descriptive statistics, and inferential statistics as in the statistical package for the social sciences (spss) version 22. the statistical tests used in analysis were pearson chi square test, spearman’s rho correlation coefficient (r), paired samples t test, friedman test statistic, and kruskal-wallis analysis of variance (anova). in addition, the tra approach by margoluis and salafsky (1998) was adopted to assess the main types of threats affecting the pas, their occurrence, their impact, and their reduction levels. following salafsky et al. (2008), threats are defined as any human activity or processes that caused destruction, degradation, and/or impairment of biodiversity targets. this approach based on three key assumptions: a) all biodiversity destructions are human-induced; b) all threats to biodiversity at a given site can be identified and c) changes in all threats can be measured or estimated (margoluis and salafsky, 1998). the tra method identifies threats, ranks them based on the criteria and assesses the progress in reducing them (rome, 1999). the tra approach followed the procedural approach developed by iucn (1998), margoluis and salafsky (1999) that involved: 5 east afr. j. biophys. comput. sci., vol. 1, no. 1 a) defining the protected area and listing all direct threats present at the site; b) ranking each threat based on three criteria: area, intensity and urgency (area refers to the percentage of the habitats in the site; intensity refers to the impact or severity of destruction caused by the threat; and urgency refers to the immediacy of the threat. out of the total threats, the highest ranked threat for each criterion receives the highest score, and lowest ranked score receives the lowest score; c) adding up the scores across all the three criteria for total ranking; d) determining the degree to which each threat has been met; e) calculating the raw score for each threat and multiplying the total ranking by the percentage calculated to get the raw score for each threat; and f) calculating the final threat reduction index score by adding up the raw scores for all threats, dividing by the sum of the total rankings, and multiplying by 100 to get the tra index as a percentage. this tra approach is much simpler and cost effective, as it measures changes in the broader human activities that threaten the integrity of the resource, and then uses that information to draw inferences on the state of the resource itself. sampling method. by rule of thumb where there is no information for an area it is possible to take 50% of expected prevalence. using 5% degree of absolute precision, 384 animals need to be sampled but, 400 animals were sampled. results the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the management strategies employed to reduce on the identified threats to enhance wildlife conservation were also documented (table 4). demographic characteristics of the respondents park staff responses the park staff respondents were segregated as 20.8% females and 79.2% males. the chi square test result was statistically significant (χ2 (1, n = 53) = 18.132, p =0.000, cramer’s value=0.445) and the high cramer’s value indicates a strong effect of gender in conservation. further analysis using the paired samples t test revealed statistically significant results with t(52) = 8.616, p = 0.000, α = 0.05 (table 1) indicating that gender plays a vital role in conservation. the staff had varying education levels with majority (43.4%) having a diploma, and 35.8% a college degree in biological science and other related discipline. (table 1) analysis by the pearson chi-square test revealed statistically significant result that education level had an effect on biodiversity conservation (χ2 (21, n = 53) = 22.222, p =0.000, cramer’s value=0.374) and the high cramer’s value indicates a very strong effect. further analysis using a paired t test revealed statistically significant results t(52) = 5.654, p = 0.000, α = 0.05 (table 1) indicating that education had a strong correlation with biodiversity conservation. on work experience demographic, 30.2% had between 11 to 15 years, and another 30.2 had over 16 years work experience in wildlife management and 6 east afr. j. biophys. comput. sci., vol. 1, no. 1 biodiversity conservation (table 1), and the pearson chi-square test revealed statistically significant result that working experience had an effect on biodiversity conservation (χ2 (196, n = 53) = 214.774, p = 0.000, cramer’s value = 0.490). the high cramer’s value indicates a very strong effect. further analysis using the paired samples t test revealed statistically significant results t(52) = 3.817, p = 0.000, α = 0.05. (table 1) further analysis on the relationship between length of work experience and level of understanding mandate of pas using spearman’s rho correlation coefficient (r) revealed statistically significance result (spearman's rho, r= 0.780, p= 0.000, n=53). table1: socio-demographic characteristics of park staff variable number (n) percentage (%) chi-square test (χ2) t test statistic gender male 42 79.2 χ2 (1, n = 53) = 18.132, p = 0.000, cramer’s value= 0.445 t(52) = 8.616, p = 0.000, α = 0.05 female 11 20.8 level of education secondary 10 18.9 χ2 (21, n = 53) = 22.222, p = 0.000, cramer’s value= 0.374 t(52) = 5.654, p = 0.000, α = 0.05 certificate 1 1.9 diploma 23 43.4 degree 19 35.8 years in service <5 years 8 15.1 χ2 (196, n = 53) = 214.774, p = 0.000, cramer’s value= 0.490 t(52) = 3.817, p = 0.000, α = 0.05 [5-10) years 13 24.5 [10-15) years 16 30.2 [15-20] years 10 18.9 >20 6 11.3 community responses responses from the local communities adjacent the wildlife protected areas also revealed that that gender is an important factor in appreciating threats to the wildlife resources and participating in their reduction as revealed by significant χ2=137.263, d.f=3, p=0.000, n=205, cramer’s value=0.350 and t(145) = 0.311, p = 0.265, α = 0.001. other demographic factors mainly age [(χ2=137.263, d.f=3, p=0.000, n=205, cramer’s value=0.350; and t(145) =0 .311, p = 0.265, α = 0.001)], education level [χ2=88.051, d.f=4, p=0.000, n=195, cramer’s value=0.159 and t(137) = 1.603, p = 0.001, α = 0.001], length of residence [χ2=174.884, d.f=55, p=0.000, n=190, cramer’s value=0.617 and t(139) = 0.545, p = 0.019, α = 0.001] and land holding [χ2=79.258, d.f=2, p=0.000, n=194, and t(139) = 3.940, p = 0.000, α = 0.001] had an influence on community participation in wildlife conservation aimed to reduce threats to wildlife resources (table 2). 7 east afr. j. biophys. comput. sci., vol. 1, no. 1 table2: socio-demographic characteristics of community respondents variable numbe r (n) percentage (%) chi-square test (χ2) t test statistic gender male 139 66.8 χ2=23.558, d.f=1, p=.000, n=208, cramer’s value=.231 t(148) = 2.063, p = 0.000, α = 0.001 female 69 33.2 age (in years) 18-31 56 27.3 χ2=137.263, d.f=3, p= 0.000, n=205, cramer’s value = 0.350 t(145) = 0.311, p = 0.265, α = 0.001 32-45 118 57.6 46-60 15 7.3 61+ years 16 7.8 level of education primary 82 42.1 χ2=88.051, d.f=4, p=0.000, n=195, cramer’s value= 0.159 t(137) = 1.603, p = 0.001, α = 0.001 secondary 57 29.2 certificate 21 10.8 diploma 20 10.3 degree 15 7.7 land holding owns land 159 82.0 χ2=79.258, d.f=2, p=0.000, n=194 t(139) = 3.940, p = 0.000, α = 0.001 landless 35 18.0 owned acreage (in hectare) <1 7 5.3 χ2=162.091, d.f=1, p=0.000, n=132, cramer’s value=0.249 t(93) = 3.060, p = 0.000, α = 0.001 1-3 84 63.6 3-5 13 9.8 5-10 21 15.9 >10 7 5.3 length of residence 1-3 years 8 4.2 χ2=174.884, d.f=55, p=0.000, n=190, cramer’s value=0.617 t(139) = 0.545, p = 0.019, α = 0.001 4-6 years 13 6.8 7-9 years 9 4.7 ≥10 years 160 84.2 occupation of respondents formal employment 15 10.2 χ2=69.023, d.f=4, p=0.000, n=148, cramer’s value=0.598 t(89) = 1.705, p = 0.092, α =0 .05 business 23 15.5 religious leaders 2 1.4 peasant farmers 85 57.4 fisher folk 23 15.5 distance of household from the park boundary <5km 130 75.1 χ2=190.465, d.f=2, p=0.029, n=173, cramer’s value= 0.201 t(145) = 3.010, p = 0.003, α = 0.001 5-10km 32 18.5 >10km 11 6.4 threats to biodiversity conservation across the landscape, the study found that all the case study national parks and wildlife reserves experience nearly similar threats which affect conservation of biological diversity therein. out of a total of 13 threats identified, 8 east afr. j. biophys. comput. sci., vol. 1, no. 1 six were primary and common threats to all and these were: i) increasing human population pressure leading to illegal activities/resource off-take, ii) poaching and illegal wildlife trade/trafficking in game meat and of recent in ivory, iii) habitat transition/changes due to invasive alien species, iv) human-wildlife conflicts arising from wildlife attacks to humans and livestock, and destroying crops, v) wild fires, and vi) boundary encroachment through agricultural development and urbanization (table 3). table3: prevailing threats within the conservation areas threats conservation area kibale queen elizabeth k ib al e se m ul ik i to ro se m lik i k at on ga q ue en el iz ab et h r w en zo ri m ou nt ai ns k ya m bu ra k ig ez i 1 human population pressure 1 1 1 1 1 1 1 1 2 poaching and illegal wildlife trade 1 1 1 1 1 1 1 1 3 habitat transition/changes 1 1 1 1 1 1 1 1 4 human-wildlife conflicts 1 1 1 1 1 1 1 1 5 wild fires 1 1 1 1 1 1 1 1 6 boundary encroachment 1 1 1 1 1 1 1 1 7 zoonotic and vector-borne diseases 1 1 0 1 1 0 1 1 8 infrastructure development 1 1 0 0 1 0 0 0 9 road kills 1 1 0 0 1 0 0 0 10 trans-boundary issues 0 1 0 0 1 0 0 1 11 poor waste management 1 0 0 0 0 1 0 0 12 variation in water quality and quantity 0 0 0 0 1 0 0 0 13 negative impacts of climate change 0 1 0 0 0 1 0 0 1=present; 0=absent the rest of the threats were subjected to oneway anova to compare their means. the results revealed sufficient evidence to conclude that the threats were different as the test statistic was significant for zoonotic diseases and vectorborne diseases (f2, 50=21.708, p=0.001), infrastructural developments (f2, 50=10.201, p=0.001), transboundary issues (f2, 50=0.677, p=0.001), and negative impacts of climate change (f2, 50=10.362, p=0.001) and hence categorized as secondary threats. however, the test statistics results were not significant for road kills (f2, 50=2.722, p>0.001), and poor waste management (f2, 50=1.802, p>0.001) hence do not pose serious threats to wildlife protected areas. further, administrative constraints pose a threat to biodiversity conservation. analysis using the one way anova test revealed that inadequate funding (f7, 45=5.095, p=0.000), insufficient incentives (f7, 45=0.35, p=0.000), and inadequate patrol equipment (f7, 45 =0.328, p=0.001) were statistically significant constraints to biodiversity conservation. other constraints not statistically significant were poor staff housing (f7, 45 =0.35, p=0.926), and weak 9 east afr. j. biophys. comput. sci., vol. 1, no. 1 support from neighboring communities (f7, 45 =0.35, p=0.937). threat reduction assessment index and protected areas threat reduction threat reduction analysis conducted showed that at all levels of area, intensity and urgency, the national parks and wildlife reserves in kibale conservation area had a higher overall average threat reduction (57.6%) compared to those in queen elizabeth conservation area (48.25%) (table 4). specifically, habitat change/transition presented the highest threat with a paltry reduction of 1.25% in queen elizabeth conservation area and 16.25% in kibale conservation area whereas boundary encroachment was the lowest threat with the highest threat reduction in both conservation areas with 86.25% in kibale conservation area and 83.8% in queen elizabeth conservation area (table 4). table -4: threat reduction in the conservation areas conservation area protected area percentage threat reduction (%tr) h ab ita t ch an ge s / tra ns iti on w ild fi re s h um an w ild lif e c on fli ct po ac hi ng an d w ild lif e tra ff ic ki ng po pu la tio n pr es su re /il le ga l ac tiv iti es b ou nd ar y en cr oa ch m en t a ve ra ge pe r pa kibale conservation area knp 50 80 70 77.5 70 70 69.58 snp 5 40 60 50 50 90 49.20 tswr 5 50 50 65 80 90 56.67 katonga 5 50 60 50 70 95 55.00 overall average in kca 16.25 55 60 60.6 67.5 86.25 57.60 queen elizabeth conservation area qenp 5 60 20 50 80 80 49.17 rmnp 0 40 80 40 40 80 46.67 kigezi np 0 10 40 30 40 70 31.67 kyambura np 0 90 50 75 80 95 65.00 overall average in qeca 1.25 52.5 53.8 54.7 63.8 83.8 48.25 key: knp=kibale national park ; snp=semuliki national park; tswr=toro-semliki wildlife reserve; kca=kibale conservation area; qenp=queen elizabeth national park; np=national park; qeca=queen elizabeth conservation area further, wild fires had reduced by 55% in kibale conservation area compared to 52.5% in queen elizabeth conservation area. human wildlife conflict was still a great challenge in all the pas with a reduction of 60% in kibale conservation area compared to 53.8% in queen elizabeth conservation area. human population pressure leading to illegal activities inside the protected areas had reduced by 63.8% in queen elizabeth conservation area compared to 67.5% in kibale conservation area. boundary encroachment by adjacent communities had reduced by 86.25% in kibale conservation area compared to 83.8% in queen 10 east afr. j. biophys. comput. sci., vol. 1, no. 1 elizabeth conservation area. armed poaching and illegal wildlife trade in game meat and game products had reduced to 60.6% in kibale conservation area compared to 53.8% in queen elizabeth conservation area (table 4). the national parks and wildlife reserves that lie entirely within uganda had their threat reduction above 50% compared to those that are shared with democratic republic of congo which had less than 50% (table 4). in addition, the focused group discussions revealed that other developments such as road construction, staff accommodation, setting up of tourist lodges and trails inside the national parks and wildlife reserves could have potential impact on the ecosystem. further, transboundary issues, political interference, poor waste management (including wastes from oil palm processing in semuliki national park) and the impacts of climate change could also pose a threat in most protected areas. threat reduction assessment index effectiveness of pa management in managing threats results of the comparison of staffing (staff per pa) and threat reduction assessment index (per pa) using paired samples t test revealed that staffing and tra index scores were moderately and positively correlated (r = 0.590, p = 0.001) and t7 = 1.412, p = 0.001. on average, staffing scores were 44.2275 points higher than tra index scores (95% ci [-29.83, 118.29]). from the box plot, the tra index values positively correlated with the staffing level in the pas. both variables appear to be symmetrically distributed (fig 2). fig. 2: relationship between staffing and threat reduction assessment index 11 east afr. j. biophys. comput. sci., vol. 1, no. 1 threat reduction assessment index and pas the threat reduction analysis looked at three criteria: area, intensity and urgency. kibale conservation area had a higher overall average tra index of 49.46% compared to queen elizabeth conservation area with 45.1%. at protected area level, kibale national park had the highest tra index of 58.35% and kigezi wildlife reserve with had the lowest with 37.76%. however, threat reduction assessment indices were independent of the size of the protected areas (fig. 3). fig. 3: threat reduction assessment indices in national parks and wildlife reserves threat reduction and mammal population in kibale conservation area anlysis of data from kibale conservation area shows a general mammal population increase over the past decades. specifically, in kibale national park, the population of the black and white colobus monkeys increased from 7,346 in 2005 to 10,459 in 2010; the baboon population increased from 11,603 in 2005 to 12,191 individuals in 2010. however, other primate populations have had a slight increase. the size of pa (x10km2), kibale conservation area (kca) knp, 79.5size of pa (x10km2), kibale conservation area (kca) snp, 22 size of pa (x10km2), kibale conservation area (kca) tswr, 54.2 size of pa (x10km2), kibale conservation area (kca) ktwr, 20.7 size of pa (x10km2), kibale conservation area (kca) kca average, 0 size of pa (x10km2), queen elizabeth conservation area (qeca) qenp, 197.8 size of pa (x10km2), queen elizabeth conservation area (qeca) rmnp, 99.5 size of pa (x10km2), queen elizabeth conservation area (qeca) kgwr, 33 size of pa (x10km2), queen elizabeth conservation area (qeca) kywr, 15.7 size of pa (x10km2), queen elizabeth conservation area (qeca) qeca average, 0 (kca) knp, 58.35 (kca) snp, 42.1 tra index (%), kibale conservation area (kca) tswr, 48.5tra index (%), kibale conservation area (kca) ktwr, 48.9 tra index (%), kibale conservation area (kca) kca average, 49.46 tra index (%), queen elizabeth conservation area (qeca) qenp, 46.37 tra index (%), queen elizabeth conservation area (qeca) rmnp, 44.19 tra index (%), queen elizabeth conservation area (qeca) kgwr, 37.76 tra index (%), queen elizabeth conservation area (qeca) kywr, 52.01 tra index (%), queen elizabeth conservation area (qeca) qeca average, 45.1 size of pa (x10km2) tra index (%) 12 tra index (%), kibale conservation area tra index (%), kibale consvation area east afr. j. biophys. comput. sci., vol. 1, no. 1 chimpanzee population has remained stable over the years (fig. 4). legend fig. 4: population estimate for primates and other mammals in kibale conservation area (raw data adopted from uwa, 2018) po pu la tio n period kibale national park po pu la tio n period katonga wildlife reserve po pu la tio n period toro-semliki wildlife reserve 13 east afr. j. biophys. comput. sci., vol. 1, no. 1 in addition, the elephant and buffalo populations have had an exponential increase. the elephant population has increased from 262 individuals in 2001 to 487 individuals in 2010; the buffalos from 124 individuals in 2001, to 402 individuals in 2010; and the bush pigs were only estimated at 400 individuals in 2001. (fig. 4) this general increase collaborates well with highest tra index of 58.35% recorded in knp (fig. 3). in katonga wildlife reserve, there was a steady increase in wildlife population from 2004 to 2013 (fig. 4). the population of the black and white colobus monkey increased from 1,342 in 2004 to 3,335 in 2013. duiker population rose from 295 in 2004 to 1,169 in 2008. the reedbuck and waterbuck had a more or less stable growth in population over the years. similarly, the mammal population in toro– semliki wildlife reserve had a general increase. specifically, the uganda kob population increased from 3,460 individuals in 1982 to 3,935 by 2015, the waterbuck population increased from 33 individuals in 1982 to through 58 individuals in 2002 to 112 by 2015, and the buffalo population increased from 219 individuals in 2002 to 449 in 2015. (fig. 4) threat reduction and mammal population in queen elizabeth conservation area the elephant population in queen elizabeth protected area (qenp, kyamburawr and kigezi wr) reduced from 4,139 in 1969 to about 150 by 1980. it then started recovering until it reached 3018 individuals in 2012. other wild animal populations have increased in qepa (fig. 5). fig 5: medium to large mammal population in queen elizabeth protected area (raw data adopted from uwa, 2018) po pu la tio n period elephant buffalo hippo uganda kob topi waterbuck lion warthog 14 east afr. j. biophys. comput. sci., vol. 1, no. 1 threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (very satisfactory), light green (tra index 51-80%) for moderate ecological integrity (satisfactory), yellow (tra index 21-50%) indicating a “concern,” (dissatisfactory) and red (tra index 0-20%) indicating “impaired” (very dissatisfactory) condition requiring immediate management action. (table 5) each national park and wildlife reserve had a score and each threat also had a score to show the level of threat reduction. on the whole, knp and kyambura wr had a “light green” score indicating moderate ecological integrity and hence satisfactory, while the rest of the pas had each an average score of “yellow” indicating significant “concern” and therefore dissatisfactory (table 5). in addition, using a scoring of 1 to 4 (where 1 very dissatisfactory, 2dissatisfactory, 3 satisfactory, and 4very satisfactory) on the state of conservation of wildlife resources in the national parks and wildlife reserves, the responses from ecological experts, selected district local governments, uganda wildlife authority, wildlife conservation societyuganda, and ministry of tourism, wildlife and antiquities indicated the overall performance of the national parks and wildlife reserves as dissatisfactory (t(25) = 14.148, p = 0.000, α = 0.001). measures by the parks that enhance effectiveness and efficiency in addressing threats in appreciation of the threats affecting wildlife conservation in the conservation areas, the study through the fgds, identified management measures the parks have instituted to enhance effectiveness and efficiency in addressing threats and these include: a) undertaking wildlife related disease surveillance in and around the national parks and wildlife reserves and conduct community sensitization programmes on wildlife related diseases b) periodically monitoring wildlife and domestic animal movements to and from the national parks and wildlife reserves c) carrying out massive conservation sensitization and educational programmes, d) strengthening community conservation through the benefit sharing scheme, problem animal management, conservation education and awareness, and community participation in boundary management. e) gathering, analysing and acting on intelligence information on illegal activities inside the national parks and wildlife reserves. f) conducting cross border and or coordinated monitoring, control and surveillance patrols inside the national parks and wildlife reserves. this also involves cross border joint planning meetings, security operations. g) put in place ecological maintenance and restoration programs especially in kibale national park and queen elizabeth national park which are intended to counteract threats to ecological integrity. these include eliminating through uprooting hyperabundant species such 15 east afr. j. biophys. comput. sci., vol. 1, no. 1 as dichrostachys cinerea and lantana camara that threaten the ecological integrity of the park ecosystems. table5: ecological integrity score card using data indicators protected area (pa) performance of ecological integrity using data indicators in the pas la rg e m am m al po pu la tio n in cr ea se fr eq ue nc y of po ac hi ng in ci de nc es h um an w ild lif e co nf lic t w ild fi re s b ou nd ar y en cr oa ch m en t r es ou rc e ha rv es tin g zo on ot ic di se as es h ab ita t c ha ng e r oa d ki lls a ve ra ge ra tin g pe r p a kibale conservation area y knp exponential lg lg dg lg lg dg lg lg lg snp n/a lg lg y r dg y tswr general increase lg lg lg dg dg n/a r r y katonga wr exponential lg lg lg dg lg lg r n/a y queen elizabeth conservation area y qenp general increase lg dg lg dg dg dg r lg y rmnp n/a y dg y dg y n/a dg n/a y kigezi wr general increase y y r lg y dg r n/a y kyambura wr general increase lg lg dg dg dg n/a r n/a lg overall rating per indicator lg lg lg dg lg lg dg r lg y lg= light green; r =red; y =yellow; dg=dark green; n/a= not applicable discussion the kibale and queen elizabeth conservation areas are key wildlife protected areas within the albertine graben which house a very rich mammal biodiversity. however, over time, they are faced with key threats that degrade their habitats and conservation in general. the threats identified in this study are similar to those reported by other researchers from a number of countries in africa (laurance et al., 2012; dimarco et al., 2014; tranquilli et al., 2014; taylor, 2015; mackenzie, 2017; ryan, 2017; chibueze, 2018; benı´tez-lo´pez et al., 2019; kolinski and milich, 2021). 16 east afr. j. biophys. comput. sci., vol. 1, no. 1 human-wildlife conflicts occur worldwide, and human injuries are the most severe manifestations of these human-wildlife conflicts (packer et al., 2005; kabuusu et al., 2018). but the killing of livestock and the crop raiding by wildlife are by far the most widespread source of such conflicts (allendorf et al., 2012; andrade and rhodes, 2012; kabuusu et al., 2018). for instance, in canada wolves are reported to have killed close to 3,000 domestic animals in 14 years, whilst elephants in india and china led to a reduction of approximately 14% and 48%, respectively of annual crop production (madhusudan, 2003; zang and wang, 2003). in tanzania, 86% of the persons living in wildlife buffer zones reported crop damage, while 10% reported the killing of livestock and poultry kabuusu (2018), and baboons have always caused significant crop destruction in uganda. the incidence of wildlife-associated human injuries increased in qenp between 2006 and 2010, and was mostly caused by hippos (kabuusu et al., 2018). weather patterns define the corresponding farming activity and the level of threats. the dry season is characterized by limited pastures and water in qenp, consequently wild animals, particularly elephants, move out of the qenp into community areas in search of water and pasture, raiding crops in the process. it was also revealed that the dry season is also the harvest season, and farmers are injured because they stay outside at night for extended periods of time protecting their crops from elephants and thieves. this seasonal change, in both animal and human behavior, mirrors temporal differences in the incidence of wildlifeassociated human injuries (kissui, 2008). this study aimed at determining the threats to conservation and how they were being addressed. data analysis and interpretation revealed major findings. the study established that socio-demographic factors of park staff mainly gender, age, education level and length of work experience play significant role in addressing threats to wildlife conservation. equally, the socio-demographic factors of local communities adjacent the national parks and wildlife reserves mainly gender, age, education level and length of residence in the community play significant role in participating in programmes that address threats to wildlife conservation. this agrees with kabir (2013) that recognition of gender roles in biodiversity management is an important step in the achievement of conservation and sustainable use of biological resources. pa management considers education as a key factor in empowering their staff with knowledge, skills and enhancing capacity and competence to conserve biodiversity. the park employees had the required skills in wildlife management and biodiversity conservation. in addition, length of work experience influences the level of understanding and implementing the mandate of pas. this implies that the park employees are knowledgeable and could provide the needed information on threats to biodiversity conservation in the park over the years. the presence of professionals corroborates the suggestion of green (1999) that some industries required specially trained personnel to actualize set goals, and biodiversity conservation is a peculiar example. the national parks and wildlife reserves in both kca and qeca are faced with key primary threats that degrade their habitats and conservation in general. these include: i) habitat transition/changes due to invasive alien species, ii) wild fires, iii) human-wildlife 17 east afr. j. biophys. comput. sci., vol. 1, no. 1 conflicts arising from wildlife attacks to humans and livestock, and destroying crops, iv) poaching and illegal wildlife trade/trafficking in game meat and of recent in ivory, v) increasing human population pressure leading to illegal activities/resource off-take, and vi) boundary encroachment through agricultural development and urbanization. also, secondary threats mainly zoonotic and vector-borne diseases, transboundary issues, negative impacts of climate change, and infrastructure developments within the pas constrain conservation efforts. these threats could be attributed to anthropogenic factors (including settlement, infrastructural development, agricultural expansion, resource off-take for livelihoods), and natural disturbances such as climate change, biological invasion, etc. these factors affect the aesthetic value, scenery, and also release wastes to the ecosystem. further, inadequate funding to the sector, insufficient incentives to park staff, and inadequate patrol equipment also constrain conservation efforts. the national parks and wildlife reserves in kibale conservation area had a higher overall average threat reduction, and overall average tra index compared to those in queen elizabeth conservation area. this higher overall average threat reduction compares well with the general increase in mammal population over the years in kibale conservation area. this could be attributed to improved management of the park and law enforcement in particular combating poaching (uwa, 2018). despite the prevailing threats, the population of large mammals has generally increased over the past decades. this collaborates well with the tra indices for each national park and wildlife reserve in each conservation area. the increase in mammal population is probably due to creation of both institutional and legal framework, and strengthened implementation of existing policies, laws and regulations. specifically, the recovering mammal population in queen elizabeth protected area could be attributed to better security within uganda, immigrations and successful breeding. this agrees well with uwa (2018) that improved pa management, increased vigilance through intelligence and patrols, and most importantly the peace, security and stability in the country and the region as a whole, and increased community conservation programs which have contributed to threat reduction. however, the low threat reduction performance of national parks and wildlife reserves shared with democratic republic of congo is probably due to their transboundary nature, which presents with it varied management challenges (gvtc, 2017). on the whole, the overall ecological integrity of kibale and queen elizabeth conservation areas was rated “yellow indicating a “concern” and hence dissatisfactory, a condition that requires immediate management action. specifically, both kca and qeca had an average tra index of less than 50%, an indication that both conservation areas only mitigate less of the pas threats. this rating of the overall performance of the national parks and wildlife reserves as “dissatisfactory” by the ecological experts, park employees, district local governments, uganda wildlife authority, wildlife conservation society-uganda, and ministry of tourism, wildlife and antiquities was a testimony that there was great “concern” to conserve wildlife resources. this level of performance could be attributed to the more emphasis the wildlife 18 east afr. j. biophys. comput. sci., vol. 1, no. 1 agency puts on animal health issues and little on ecosystem health. conclusion the study established that the national parks and wildlife reserves are majorly threatened by habitat transition/changes, wild fires, humanwildlife conflicts, armed poaching and illegal wildlife trade/trafficking, increasing human population pressure, and boundary encroachment through agricultural development and urbanization. other threats are zoonotic and vector-borne diseases, transboundary issues, negative impacts of climate change, and infrastructure developments within the pas which constrain conservation efforts. creation of both institutional and legal framework, and strengthening implementation of existing policies, laws and regulations is key to biodiversity conservation success. protection of the integrity of wildlife conservation areas requires an integrative approach of interventions that focus on both animal health, and ecosystem health at national and transboundary level. reduction in threats affecting wildlife conservation areas calls for a multidisciplinary approach involving local communities, park management, and security agencies. therefore, improved park management, increased vigilance, and peace, security and stability in a country or region are prerequisites to achieve conservation of wildlife and other biodiversity. various management approaches to enhance effectiveness and efficiency in addressing threats must include, but not limited to, undertaking wildlife related disease surveillance, periodically monitor wildlife in and outside the national parks and wildlife reserves, conduct conservation awareness and education, strengthen community conservation through the benefit sharing programme, strengthen intelligence information on illegal activities, strengthen adaptive management to address threats to ecological integrity. recommendations the wildlife agency should strengthen adaptive management as a strategy to restore all degraded areas inside the national parks and wildlife reserves and carry out periodical environment audits.. the wildlife agency should strengthen law enforcement and national-level coordination with the community and concerned stakeholders to combat poaching and other illegal activities in the park. finally, more research should be conducted to investigate the impact of tourism infrastructure development on ecological integrity of the national parks and wildlife reserves. acknowledgments we thank the people adjacent the national parks and wildlife reserves within the kibale and queen elizabeth conservation areas for providing information. thanks also go to uganda wildlife authority for allowing us carry out the study, and their staff for providing us with useful information. declarations of interest: none authors’ contributions j.k. initiated and shared the research idea, drafted the concept, coordinated the data collection and analysis and wrote the first draft 19 east afr. j. biophys. comput. sci., vol. 1, no. 1 of the manuscript. n.m.m and c.k.t assessed the draft concept of the manuscript, made conceptual guidance to collect right data and made critical intellectual adjustments on the first manuscript to make it a clear scientifically and logically drafted manuscript. all authors assessed and approved the final copy of the manuscript for submission. references allendorf t.d., aung m. and songer m. 2012. using residents' perceptions to improve park-people relationships in chatthin wildlife sanctuary, myanmar. j. environ. manag. 99, 36-43. andrade g.s. and rhodes j.r. 2012. protected areas and local 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elephant (elephas maximus), with a focus on human elephant conflict in simao, china. biol. conserv. 112: 453459. 22 cover v1.pdf (p.1) slide number 1 blank page.pdf (p.2) table of contents vol1.pdf (p.3-5) guideline to authors_ eajbcs.pdf (p.6-14) back cover.pdf (p.15) editorial board members table of contents slide number 4 slide number 5 slide number 6 volume 1.pdf 1_biodiversity conservation joseph katswera, norah m. mutekanga and charles k. twesigye* fig 1: map showing kibale and queen elizabeth conservation areas and location of study sites. the study documented the threats to biodiversity in the case study national parks and wildlife reserves. both primary and secondary threats were identified (table 2), and their threat reduction percentages and indices calculated (table 3). the managem... demographic characteristics of the respondents threats to biodiversity conservation threat reduction assessment index and protected areas threat reduction threat reduction assessment index effectiveness of pa management in managing threats fig. 2: relationship between staffing and threat reduction assessment index threat reduction assessment index and pas threat reduction and mammal population in kibale conservation area threat reduction and mammal population in queen elizabeth conservation area threat reduction and ecological integrity rating the data indicators were analysed and various scores were assigned basing on the computed tra index in table 4. each indicator of ecological integrity was assigned a color score: dark green (tra index 81-100%) for “acceptable” ecological integrity (ve... table5: ecological integrity score card using data indicators 2_prevalence of trypanosomiasis 5_climate change_biju 7_public health implications public health implications of bovine cysticercosis from cattle slaughtered at dilla municipal abattoir, southern ethiopia fikadu tesfaye, jemere bekele, mesele abera and nebyou moje* hawassa university faculty of veterinary medicine, p.o. box05, hawassa, ethiopia bovine cysticercosis is a cystic stage of taenia saginata, zoonotic parasite with its significant impact on human health. the cystic stage usually affects the muscle of cattle where humans are susceptible from the contaminated raw meat (taylor et al.,... generally cysticercosis in animals is expected to have insignificant clinical effect. nevertheless, it is economically important as it causes carcass condemnation arising from heavy infestation with the cysticerci of t. saginata. additionally, there i... 9_fish aeromonas bacteria cover 1-1.pdf slide number 1 editorial board members back cover 1.pdf slide number 1 introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction east east afr. j. biophys. comput. sci. (2023), vol. 4, issue. 1, 18-27 *corresponding author: email: rabirhanu@gmail.com, https://dx.doi.org/10.4314/eajbcs.v4i1.2s study of reaction mechanisms in α + 69ga reaction at ≈10 – 50 mev f. k. amanuel 1department of applied physics, hawassa university, hawassa, ethiopia keywords: reaction cross-section; complete code; reaction channel; excitation function abstract the excitation functions of 69ga(α, n)72as, 69ga(α, 2n)71as, 69ga(α, 3n)70as, 69ga(α, x)69ge, 69ga(α, x)68ga and 69ga(α, x)67ga reactions formed in the interaction of αprojectile with 69ga-target were studied at ≈ 10-50 mev. the produced nuclei were different isotopes of as, ge, and ga, some of which have important medical applications. the theoretical model predictions were based on the statistical code complete, and the predicted results were compared and discussed with existing experimental data. good agreement between the theoretical predictions and experimental results were obtained. pearson's relational statistics revealed moderate to strong positive associations between the theoretically predicted and experimentally measured reaction cross-sections. furthermore, the present investigation revealed significant pre-compound contributions in the studied energy range. therefore, it is important to consider the admixture of preequilibrium and equilibrium modes of reactions when predicting the reaction crosssections. introduction advances in accelerator technology and cyclotrons have enabled the use of lightand heavy-charged nuclei as projectiles in nuclear reactions. this development has improved our understanding of the reaction mechanism and nuclear structure at various energies near and above the coulomb barriers (cavinato et al., 1995; amorini et al., 1998; gadioli et al., 1998). for example, at moderate excitation energies, reactions induced by nucleons and light-charged projectiles are found to proceed through the equilibrium (eq) and preequilibrium (pe) mode reactions (baure et al., 1995;agrawal et al., 2001; patronis et al., 2007; johari and saxena, 2015). to understand these reaction mechanisms, reaction cross-section data evaluation is essential. accordingly, comparative studies based on experimental data and theoretical predictions are demanding. in this regard, nuclear reaction model-based computer codes can swiftly help to predict unknown reaction cross-sections and thus improve computer code predictions. studies of light-charged induced nuclear reactions help better understand the reaction mechanisms and test the validity of various available and newly evolving computer codes. furthermore, in light-charged induced nuclear reactions, the processes of pe and eq particle(s) emissions are vital in comprehending and characterizing the reaction mechanisms, attributable to the strong competition between east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article https://dx.doi.org/10.4314/eajbcs.v4i1.2s east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 18-27 19 pe and eq mode of reactions at moderate excitation energies. numerous studies have compared theoretically predicted and experimentally measured reaction cross sections for light-charged particle induced reactions, aiming to elucidate the underlying reaction mechanisms (agarwal et al., 2002; abhishek et al., 2008; amanuel et al., 2011; yigit and tel, 2014; asres et al., 2018; asres et al., 2019; amanuel, 2021). however, reasonable comparative reaction mechanisms studies between theory and experiment of 72as, 71as, 70as, 69ge, 68ga, and 67ga reaction products produced in α-projectile induced reactions on 69ga-target at ≈10 – 60 mev, have not been investigated efficiently; therefore, further investigations and scientific evidence are required (ismail 1990; rezvi et al., 1989; didik et al., 1994). furthermore, understanding the reaction mechanisms induced by a light-charged projectile, such as in α + 69ga reaction helps to investigate new works on producing pure and optimized 72as and 68, 67ga radionuclides that are useful in medical applications embracing the present and possible future needs. the present work investigates the reaction mechanisms involved in the interactin of αprjectile with 69ga-target at ≈10 50 mev. excitation functions of 69ga(α, n)72as, 69ga(α, 2n)71as, 69ga(α, 3n)70as, 69ga(α, x)69ge, 69ga(α, x)68ga and 69ga(α, x)67ga reactions were predicted using the statistical model code complete. the corresponding experimental data were collected from the exfor database (levkovski, 1991). the complete computer code has proven effective in reaction mechanism studies, particularly for lightand medium-nuclei induced reactions (agarwal et al., 2002; asres et al., 2018; asres et al., 2019). theoretical background several theoretical nuclear reaction model-based computer codes have been used to predict reaction cross-sections (abhishek et al., 2008; yigit and tel, 2014; amanuel, 2021). the nuclear reaction mechanisms change with lightcharged projectile energies near and above the coulomb barrier. the reaction mechanism is considered to proceed through eq as well as pe emission of particles at moderate excitation energies (≈1060 mev) (baure et al., 1995; agrawal et al., 2001; pal et al., 2005; johari et al. 2015; asres et al., 2019). the eq mode of reaction mechanism dminates in the low energy regin (in general, below 20 mev). furthermore, this reaction mechanism occurs in a nuclear reaction time scale of abut 10-16 to 10-18 s. in the eq mode of reactions, the projectile is captured by the target nucleus, and its energy is shared and re-shared amongst the nucleons, losing their identity and forming a single excited cmplex system that eventually leads to a fully equilibrated cmpound nucleus (cn). the eq emissions of nuclear reactions are usually treated using statistical models. for example, the hauser-feshbach (hauser and feshbach, 1952) formalism considers the angular momentum and the nuclear level structure to define the eq emission spectrum. on the other hand, in the weisskopf-ewing (weisskopf and ewing, 1940) eq emission formalism, angular momentum, and parity are not considered. the pe mode of reaction mechanism becomes increasingly crucial at a relatively high energy region (above ≈20 mev). therefore, the pe emissions of nuclear reactions occur before the thermalization of a composite system and are usually treated using non-statistical models; and the popular models used for the description and calculations of the pe mode of the reaction mechanism are the exciton model (griffin, 1966; blann, 1975; agassi et al., 1975), hybrid model (blann, 1971), and geometry-dependent hybrid model (blann and vonach, 1983). various computer codes were developed for years based on different nuclear reaction models east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 18-27 20 that helped study nuclear structure and reaction mechanisms (young et al., 1992; uhl and strohmaier, 1976; strohmaier and uhl, 1980). the alice-91 (blann, 1991) analytic code developed by blann was also vastly used over the years to predict reaction cross-sections in the intermediate energy regions. the computer code complete (ernst, 1997) is an advanced modified version of the alice-91 code family and has been successfully applied to the calculation of eq and pe reaction cross-sections (aydin et al., 2010; asres et al., 2018; asres et al., 2019; amanuel, 2021). complete code the computer code complete with new corrections and capabilities has successfully predicted nuclear reaction cross-sections, especially for reaction mechanisms studies (asres et al., 2018; asres et al., 2019; amanuel et al., 2011). this code employs the weisskopfewing formalism (weisskopf and ewing, 1940) for the eq reaction component and hybrid (h) model (blann, 1971) as well as the geometric dependent hybrid (gdh) model of blann (blann and vonach, 1983) for the pe reaction component. according to the weisskopf-ewing model, and based on bohr's independence hypothesis, the nuclear reaction cross-section for a reaction with entrance channel α and exit channel β can be expressed as (1) where is the crss-sectin for the frmation of the cn and , , respectively, represent the energy average width for the decay of the cn in channel β, and the energy averaged total width. in eq. (1) can be given as: where and represent the ejectile's reduced mass and spin, respectively, the quantity represents the inverse reactin crss-sectin, and u the excitatin energy of the residual nucleus. corresponds to the total single-particle level density at excitation energy, e. the h model formulation of blann and vonach (blann and vonach, 1983) for pe reaction differential cross-section is given by: (2) , (3) here, represents the reaction cross-section, and represents the number of particles of the type ν emitted into the unbounded continuum with channel energy between ε and ε+dε. the quantity in the first set of the square bracket of eq. (3) represents the number of particles to be found (per mev) at a given energy "ε" with respect to the cntinuum for all scattering processes leading to an "n" excition configuration. the nucleon-nucleon scattering energy partition function, represents the number of combinations with which n exciton may share the excitation energy, eex and represent the excitn number of ν type nucleon for a given total excitn state n. corresponds to the single-particle level density for nuclen of the “ν" type. the secnd set of a square bracket in eq. (3) represents the fraction of the ν type particles at energy ε, which should underg emission int a cntinuum rather than making an inter-nuclear transition. the represents the average fractin f the initial east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 18-27 21 ppulation surviving the treated excitn number. the quantity represents the cntinuum emissin rate fr particles with "ε" channel energy, and represents the intranuclear transitin rate. the quantities u and e represent the residual nucleus and composite system excitation energies, respectively. the gdh hybrid model has successfully reproduced a wide range of nuclear reaction data (blann, 1972; blann and vonach, 1983; harp et al., 1966). the gdh mdel is a modified versin of the h mdel in which the nuclear gemetry effects are cnsidered. in addition, the gdh mdel onsiders the reduced matter density, hence the shallow potential. accordingly, the pe decay formalism incorporated the diffused surface prperties sampled by higher impact parameters. the differential crss-section for pe emissin in the gdh model is frmulated as follows: (4) the quantity represents the transmissin cefficient fr the lth partial wave, and represents decay prbability at channel energy “ε” and rbital angular mmentum “l”. is the reduced de-brglie wavelength. pearson’s correlation coefficient the prediction quality of our optimization in fitting complete code using essential input parameters for the experimental reaction cross sections available in the literature was evaluated using the statistical pearson’s coefficient, r(sedgwick, 2012; wang, 2012; patrick, 2018). in addition, the present wrk used pearsn's crrelation cefficient to provide information on the linear relational strength between the complete projected and experimentally measured reaction crss-sections. pearson's crrelation cefficient, r, is given by: (5) where n is the number of the theretical and experimental data pints, and are the theretical and experimental crss-sectin of the ith value, respectively. eq. (5) returns unitless values for r between -l and +l, where +l represents a strong positive relatinship, -l indicates a strng negative relatinship; and 0 indicates n relatinship. if 0 < r < 0.3, the crrelation is weak and psitive, if 0.3 ≤ r < 0.7 the crrelation is mderate and psitive; and if 0.7 ≤ r < l the crrelation is strng and psitive. results and discussion excitation functions of 69ga(α, n)72as, 69ga(α, 2n)71as, 69ga(α, 3n)70as, 69ga(α, x)69ge, 69ga(α, x)68ga and 69ga(α, x)67ga reactions produced via eq and pe processes were considered at ≈ 10-50 mev. the experimentally quantified excitatin functins were cmpared with the theretical model code complete predictins, which account for both eq and pe processes. in this cde, the level density parameter a, which predominantly affects the eq compnents of a crss-sectin, is calculated frm the expressin a = a/k mev-1, where a is the nuclen number of a cn and k is an adjustable constant. k may vary t match the experimenta1 data. the initial exciton number no (no= n+p+h, which is described by the number f neutrns (n), the number of prtons (p) in excited states, and the number of hles (h) after the first cllision) that governs the pe component, represents the initial cnfiguration east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 18-27 22 f the number of particles in the excited states and the number of hles after the first cllision. in the present work, to match the experimental data, the values of important input parameters k(k=8, 10, 12) and no (no=4, 5, 6) were varied for a representative 69ga(α, n)72as reaction. figure 1 displays the experimentally measured excitation functions and theoretical predictions using different k and no values for 69ga(α, n)72as reaction. 15 20 25 30 35 40 45 50 55 -400 -200 0 200 400 600 800 1000 1200 a) 69 ga(, 2n) 71 as (levkovski, 1991) complete (k=8) complete (k=10) complete (k=12)  ( m b ) e lab (mev) 15 20 25 30 35 40 45 50 55 -400 -200 0 200 400 600 800 1000 1200 b) 69 ga(, 2n) 71 as (levkovski, 1991) complete (n o =4) complete (n o =5) complete (n o =6)  ( m b ) e lab (mev) figure 1: experimentally measured and theoretically calculated excitation functions for 71as residue. the curves represent the theoretical predictions (admixture pe and eq) for different values of k (k = 8, l0, and l2) in panel (a) and no (no = 4, 5, and 6) in panel (b). the open circles represent the experimental cross-sections. as this figure indicates, the measured excitation function is well reproduced by complete code for values of k=8 and no=5. it may be bserved frm fig 1(a) that the predicted excitation functions fr different k values are related; if they differ, the alterations are minimal. for other reactin channels ppulated in the interaction of α-prjectile with 69gatarget, a combination of k=8 and no=5 has been consistently used t predict the reaction crsssectins. a) 6 9ga(α, n)72as reaction when α-projectile bombarded 69ga-target, a composite [73as]* nucleus is produced in excited states. the excited [73as]* nucleus then emits a neutron leaving the 72as nucleus as a residue, i.e., α + 69ga [73as]* n + 72as figure 2(a) displays the experimentally measured excitation function and the complete code predictions for 69ga (α, n)72as reaction. as shown in figure 2(b), the experimentally quantified excitation function is comparatively higher than the theoretically predicted excitation functions (with and without pe contribution), thugh the shapes f the tw excitatin functins showed a similar trend. the observed enhancement on the measured crsssection may be attributable to impurity contributions from the heavier residue(s). in addition, pearsn's crrelation cefficient east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 18-27 23 between theretically predicted and experimentally measured prduction crosssections has a value of r=0.96. hence, the theoretical results indicated a strong and positive correlation with the experimental. b) 69ga(α, 2n)71as reaction in the case f 69ga(α, 2n)71as reactin, the residue 71as may be produced following the emission of two neutrons from an excited composite nucleus, [73as]*, i.e., fig. 2(b) shows the theoretically predicted excitation functions (with and without the contribution of pe reaction) along with the experimentally measured excitatin functin for 69ga(α, 2n)71as reaction. as shown in this figure, the predictions of the complete code, after incorporating the pe reaction, agree with the measured excitation function. furthermore, pearson's correlation coefficient value (r ≈ 0.94) indicated a strong and positive correlation between theretically predicted and experimentally measured productin crsssectins. c) 69ga(α, 3n)70as reaction the measured excitation function and theoretical predictions obtained from complete code for 70as residue populated via (α, 3n) channel are shown in figure 2(c). note that in the 69ga(α, 3n)70as reaction, the residue 70as may be formed through the reaction: it may be observed from figure 2(c) that up to 40 mev (up to the peak portion), the predicted excitation function after incorporating pe contribution, in general, reproduced the measured excitation function satisfactorily. however, above 40 mev (in the tail prtion of the excitatin functin), the predicted values are higher than the experimental data. moreover, pearson's correlation coefficient between theoretically predicted and experimentally measured reaction crss-sectins has a value of r=0.86. hence, the theoretical results indicated a strong and positive correlation with the experimental. d) 6 9ga(α, x)69ge reaction in 69ga(α, x)69ge reaction, 69ge residue may be formed through the emissions of unidentified particles, x from the composite nucleus, [73as]* via (α, x) complex channel. as seen in figure 2(d), the predicted excitation functions with the inclusion of pe contribution is in good agreement with the measured excitation function. 15 20 25 30 35 40 45 50 55 -400 -200 0 200 400 600 800 1000 1200 b) 69 ga(, 2n) 71 as (levkovski, 1991) complete (pure eq) complete (pe and eq)  ( m b ) e lab (mev) 10 15 20 25 30 -400 -200 0 200 400 600 800 1000 1200 a) 69 ga(, n) 72 as (levkovski, 1991) complete (pure eq) complete (pe and eq)  ( m b ) e lab (mev) 30 35 40 45 -400 -200 0 200 400 600 800 1000 1200 c) 69 ga(, 3n) 70 as (levkovski, 1991) complete (pure eq) complete (pe and eq)  ( m b ) e lab (mev) 36 38 40 42 44 46 48 -200 0 200 400 d) 69 ga(, x) 68 ge (levkovski, 1991) complete (pure eq) complete (pe and eq)  ( m b ) e lab (mev) α + 69ga [73as]* 2n + 71as α + 69ga [73as]* 3n + 70as east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 18-27 24 15 20 25 30 35 40 45 50 55 -400 -200 0 200 400 600 800 1000 1200 b) 69 ga(, 2n) 71 as (levkovski, 1991) complete (pure eq) complete (pe and eq)  ( m b ) e lab (mev) 10 15 20 25 30 -400 -200 0 200 400 600 800 1000 1200 a) 69 ga(, n) 72 as (levkovski, 1991) complete (pure eq) complete (pe and eq)  ( m b ) e lab (mev) 30 35 40 45 -400 -200 0 200 400 600 800 1000 1200 c) 69 ga(, 3n) 70 as (levkovski, 1991) complete (pure eq) complete (pe and eq)  ( m b ) e lab (mev) 36 38 40 42 44 46 48 -200 0 200 400 d) 69 ga(, x) 68 ge (levkovski, 1991) complete (pure eq) complete (pe and eq)  ( m b ) e lab (mev) figure 2. experimentally quantified and theoretically predicted excitation functions for 72as, 71as, 70as, and 69ge residues. the curve represents the theretical prediction, and the symbls represent the experimental crss-sectins. pearsn's crrelation cefficient between theretically predicted and experimentally measured production cross-sections is r ≈ 0.99. this result indicated a strong positive association between the predicted and measured production cross-sections. a) 6 9ga(α, x)68ga reaction 68ga residue is produced when unidentified particles (x) are emitted from an excited composite nucleus [73as]* via 69ga(α, x)68ga complex reaction channel. figure 3(a) shows the theoretically predicted excitation and experimentally measured excitation functions. it may be bserved frm figure 3(a) that the predicted (pure eq) excitation function is in good agreement with the measured one. furthermore, pearsn's crrelation cefficient between the predicted (pure eq) and measured crss-sections have a value of r ≈ 0.5, indicating a moderate and positive correlation between the measured and the predicted excitation functions. b) 69ga(α, x)67ga reaction the measured excitation functins, alng with the theretical predictins (with and without the contribution of pe reaction) for 69ga(α, x)67ga complex reaction channel, are shown in figure 3(b). note that 67ga residue is produced when unidentified particles (x) are emitted from an excited composite nucleus [73as]* via 69ga(α, x)67ga complex reaction channel. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 18-27 25 25 30 35 40 -200 0 200 a) 69 ga(, x) 68 ga (levkovski, 1991) complete (pure eq) complete (pe and eq)  ( m b ) e lab (mev) 30 35 40 45 50 -200 0 200 (levkovski, 1991) complete (pure eq) complete (pe and eq) b) 69 ga(, x) 67 ga  ( m b ) e lab (mev) figure 3. experimentally measured and theoretically calculated excitation functions for 68ga and 69ga residues. the curve represents the theretical prediction, and the symbls represent the experimental crss-sectins. figure 3(b) shows that the pure eq-predicted excitation function agrees with the experimentally measured excitation function. furthermore, pearson's correlation coefficient value (r≈0.98) indicated a strng and psitive crrelation between theretically predicted and experimentally measured reaction crsssectins. conclusion excitation functions of 69ga(α, n)72as, 69ga(α, 2n)71as, 69ga(α, 3n)70as, 69ga(α, x)69ge, 69ga(α, x)68ga and 69ga(α, x)67ga reactions populated in the interactin of α-prjectile with 69ga-target were studied at ≈10 -50 mev. except for 69ga(α, x)68ga reaction, the theoretically predicted (admixture of pe and eq reactions) reaction crss-sections using the statistical mdel code complete with the k=8 and no=5, in general, were fund to be in gd agreement with the experimentally measured excitation functions. furthermore, pearsn's correlation cefficients r mderate to strng psitive crrelatins between the theretically predicted and experimentally measured excitation functions for investigated reaction channels. the present results also disclosed a significant contribution from a pre-equilibrium reaction, particularly in the tail sections of the excitatin functions. thus, the admixtures of pre-equilibrium and equilibrium modes of reactions must be considered when predicting total reaction crosssections. acknowledgment the author gratefully acknowledges webshet beharu and anabel t. abosse for their valuable scientific discussions that contributed to this work. the author remains solely responsible for all opinions and any errors. references abhishek y., singh p. p., sharma m. k., singh d. p., singh b.p., prasad r., musthafa m.m. and calicut u. 2008. large pre-equilibrium contribution in α + natni interactions at ≈8− 40 mev. phys. rev. c 78, 044606. agrawal a., bhardwaj k. m., rizvi a. i. and chaubey a.k. 2001. equilibrium and pre-equilibrium studies https://inspirehep.net/authors/1062614 https://inspirehep.net/authors/988557 https://inspirehep.net/authors/1870968 https://inspirehep.net/authors/1062815 https://inspirehep.net/authors/1062816 https://inspirehep.net/authors/1062816 https://inspirehep.net/authors/1923168 https://inspirehep.net/authors/2176683 https://inspirehep.net/institutions/903700 https://inspirehep.net/institutions/903700 east afr. j. biophys. comput. sci. 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and chadwick m. b. 1992. international center for theortical physics workshop on computation and analysis of nuclear data relevant to nuclear energy and safety: h4.smr614/1 (italy). . https://doi.org/10.1136/bmj.e4483 east afr. j. biophys. comput. sci., vol. 2, issue 1 groundwater quality evaluation and its suitability for domestic and irrigation use in the hard rock terrain of olakkur block, tamilnadu, india vinodh. d1, senthilkumar.s2, gowtham.b1 , wegenetalelign3and jeevanandam m*3 1department of geology, presidency college(autonomous),chennai – 600 005, india 2department of earth sciences, pondicherry university, puducherry, india 3department of geology, college of natural and computational sciences, hawassa university, hawassa, ethiopia. keywords: corrosion; hydrogeochemical; ollakur block; irrigation quality; groundwater quality introduction in most parts of india ground water play a vital role and major source for drinking and agricultural purposes. the quality of groundwater is a function of physical and chemical parameters that are greatly influenced by anthropogenic activities and geological formations (krishna kumar et al., 2011). the chemistry of groundwater is not only related to lithology and rock water interaction but also reflects inputs from soil, atmosphere and pollutant sources such as saline intrusion, mining activities, industrial and domestic wastes (babiker et al., 2007). groundwater also gets polluted due to excessive irrigation practices (sujatha and reddy, 2003). understanding journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx 34 east african journal of biophysical and computational sciences research article *corresponding author: email: jeevam24@hu.edu.et abstract ground water is the main source of water for agriculture and domestic use in the study area. this study was aimed to evaluate the groundwater quality for domestic and irrigational purposes. groundwater samples were collected from twenty five locations in both pre-monsoon and post-monsoon months and examined for various physico-chemical parameters such as ph, total dissolved solids, total hardness, calcium, magnesium, sodium, potassium, bicarbonate, sulphate, nitrate and chloride. to assess the domestic suitability of groundwater, all these parameters were compared with the standards of world health organization and indian standards. sodium adsorption ratio (sar) and us salinity diagram were used to evaluate the groundwater for irrigation suitability. at some locations sodium and potassium values were higher than the prescribed limits. the sar values were less than 10. based on united states salinity laboratory staff (ussl) diagram the dominant categories were c2-s1, c3-s1, c2-s1, c3-s1, c3-s2 in both pre and post-monsoon. groundwater samples were classified as na-hco3 and na-cl water type in pre-monsoon and ca-na-hco3 and na-cl types in post-monsoon. the geochemical analysis revealed that the groundwater samples were fit for domestic purpose. the irrigation quality assessment based on sodium adsorption ratio and us salinity diagram suggested that, most of the groundwater samples were fit for irrigational activities except in certain locations where sodium and salinity values were high. based on piper water classification, mixing process and evaporation were the dominant geochemical process in the study area. mailto:jeevam24@hu.edu.et east afr. j. biophys. comput. sci., vol. 2, issue 1 geochemical evolution of groundwater in arid and semi-arid regions would be helpful for sustainable development, consumer protection from noxious substances/contaminants and proper management of water resources (jalali, 2009; furi et al., 2011). geographic information system (gis) is an effective tool for assessing and mapping groundwater quality and its utilization for irrigation and drinking needs (srinivasamoorthy et al., 2011; ravikumar et al., 2013). the geological formations and anthropogenic activities are greatly influenced the groundwater quality in the study area. agriculture practice is the major economic activity in the study area. surface water resources are very scarce and groundwater resources represent water source for drinking and agricultural purposes for the people living in this area. it is widely accepted that the utilizations of groundwater resources are closely associated with their geochemical properties (abderamane, 2013; krishna kumar et al., 2015). for effective and safe use of ground water for various agricultural and domestic uses, sufficient information should be available. however, there is no such study in the area. therefore, the present study was attempted with the objective of assessing the groundwater quality and its suitability for drinking and irrigation purpose. materials and methods study area the study area, olakkur block, is located between latitudes 12°10’00” and 12°25’00” n and longitudes 79◦30’00” and 79◦50’00” e, in villupuram district (figure 1) and covers an area of about 277.64 sq.km. the study area falls in the following survey of india topographic sheets 57p/11, 57p/12, 57p/15 and 57p/16. the area is bounded by the kancheepuram district in the north tiruvannamalai district in west, marakanam block and mailam block of villupuram district in the east and south, respectively. agriculture is the main activity where paddy is the principal crop, and crops such as sorghum, maize, ragi, pulses, chillies, groundnut, cotton and sugarcane are also cultivated. geology and geomorphology 35 east afr. j. biophys. comput. sci., vol. 2, issue 1 the charnockite of archaean age covers most part of the study area (figure 2). hornblende biotite gneiss and pink migmatite is seen along north western part of the study area. the rock shows typical granular texture with quartzofeldspathic composition. conglomerate is exposed in north part near the marakanam region. thickness of weathering varies in different places and it depends on the mechanical and chemical action on the granitic rocks. prominent vertical and oblique joints and fractures are observed from well inventories. the trend of the granitic gneiss is n60 °e and dipping towards s35°e which are noticed on the n-ne of melmalayanur. the trend also varies from n35°e to n45°e on the northern and southern side of gingee. this is due to the changes in tectonic disturbance, which also controls the movement of groundwater. charnockite is seen in north-west and south east which extends up to melmalayanur and ne till gingee around perumpugai village. it is composed of blue quartz, feldspar and hypersthene. in some part of the study area charnockiteacts as intrusive rock (senthilkumar et al., 2014). the weathering thickness is moderate and the joints and fractures are limited. the geo-morphological study area is based on the fact that the specific characteristics of each of the landform vary greatly in terms of shape, dimension, and thickness of the overburden material, permeability, porosity etc, depending on the underlying rock type, structural control, climate and vegetative cover. geomorphology of the area dominantly consists of the deep buried pediment, shallow buried pediments and pediments. methodology base boundary map was prepared using survey of india topo-sheets of the study area, and data such as rainfall, geomorphology, geology and land use were collected from central and state government agencies. during field study, groundwater samples were collected from 25 locations from both bore well and dug wells during pre-monsoon and post monsoon seasons in 2020. the samples were analysed for major ions by employing the standard water quality analysis procedures (apha, 1995). physical parameters such as ph and ec were measured using potable meters in the field. major ions such as ca, mg were analyzed titrimetrically using standard edta (0.2n) solution. sodium (na) and potassium (k) were estimated, using a flame photometer (model cl354). carbonate (co3) and bicarbonates (hco3) were analysed by standard hcl titration method and sulphate (so4) was analyzed, using a spectrophotometer (model sl27). the corrosivity ratio of water was calculated by using the formula of ryznar (1944) corrosivity ratio (cr) =       + + 100 )/( 2 96 )/(2 5.35 )/( 33 4 lmghcoco lmgsolmgcl total hardness denotes the concentration of calcium and magnesium in water and is usually expressed as the equivalents of caco3, calculated by the following formula total hardness (th) = 2.497 ca+4.115 mg (karanth, 1991). 36 east afr. j. biophys. comput. sci., vol. 2, issue 1 the spatial analysis of various physico-chemical parameters was carried out using the arcgis®9.1 software. an inverse distance weighed (idw) algorithm was used to interpolate data spatially and estimate values between measurements. this interpolation technique calculates a value for each grid node by examining surrounding data points that lie within a user-defined search radius (burrough and mcdonnell, 1998). all of the data points are used in the interpolation process and the node value is calculated by averaging the weighted sum of all the points. results and discussion assessment of groundwater quality the spatial distribution of total dissolved solids (tds), total hardness (th) and corrosivity ratio for pre and post-monsoon is shown in figure 3. 37 east afr. j. biophys. comput. sci., vol. 2, issue 1 80 the physico-chemical analysis of the groundwater samples for both seasons is presented in table 1 & 2. 38 figure 3: tds, th and corrosivity ration for pre-monsoon and post-monsoon east afr. j. biophys. comput. sci., vol. 2, issue 1 81 table 1: physico-chemical characteristics of groundwater in the study area premonsoon sample locations ph tds ca mg na k hco3 cl so4 no3 sar 1 7 756 31 18 153 18 393 126 27 1 6 2 7.2 399 29 5 48.6 5.4 207 22 10 3 2 3 7.2 1106 50 31 223.2 24.8 442 253 64 10 7 4 7.3 1533 77 55 217 25 613 250 81 9 5 5 6.8 1078 44 27 207 23 431 156 140 8 7 6 7.4 417 21 18 58 6 167 69 35 2 3 7 7.1 627 59 9 89 10 313 82 21 9 3 8 6.9 910 20 38 150 17 437 119 40 4 5 9 6.8 721 59 13 152 25 346 164 43 2 5 10 7.2 1155 71 40 225 30 462 336 43 4 6 11 7 483 48 8 60 10 242 46 42 2 2 12 7 1428 45 68 335 15 571 465 26 6 8 13 7.3 767 64 13 129 21 345 123 79 6 4 14 6.7 357 22 4 61 7 171 41 25 2 4 15 7.5 966 32 26 189 21 386 192 51 7 7 16 7.3 900 77 8 176 20 360 211 59 4 6 17 6.8 1229 99 33 224 24 491 260 148 5 6 18 6.9 1778 118 49 366 41 711 446 166 3 8 19 7.5 963 30 18 230 26 385 250 36 6 9 20 6.9 1736 107 27 462 51 694 577 103 10 12 21 7.4 350 25 6 67 7 140 76 27 5 3 22 7.2 956 58 11 260 29 382 307 67 6 9 23 7.3 595 44 13 87 10 238 100 35 6 3 24 6.6 403 27 8 59 7 161 69 18 4 3 25 6.9 606 48 10 183 20 297 58 53 7 4 ph: the ph value of groundwater samples ranging from 6.6-7.5 and 6.7-7.7 during pre and post-monsoon, respectively. who standards reveals that all the groundwater samples from the study area during both monsoons exceed the most desirable limit of 6.5 but under maximum allowable limit of 8.5. the ph values indicate slightly acidic nature in some locations which could be attributed to the weathering process of underlain geology. 39 east afr. j. biophys. comput. sci., vol. 2, issue 1 table 2: physico-chemical characteristics of groundwater in the study area postmonsoon sample locations ph tds ca mg na k hco3 cl so4 no3 sar 1 7.4 602 32 15 71 8 313 31 12 2 3 2 7.1 438 21 12 51 6 228 15 18 4 3 3 7 1302 92 8 331 37 521 442 11 3 10 4 7.1 1022 105 9 171 19 409 223 56 9 5 5 7.1 763 47 12 159 18 305 161 67 8 6 6 7.2 378 23 15 59 6 151 81 27 2 3 7 6.8 550 42 5 89 10 275 73 9 8 4 8 7.1 777 35 27 105 12 373 73 40 5 4 9 7.4 637 55 17 99 11 306 123 24 2 3 10 7.2 378 25 9 73 8 151 100 10 4 4 11 6.7 441 35 10 71 8 221 61 35 2 3 12 7.1 1358 50 22 377 42 543 461 31 5 12 13 6.9 693 57 13 113 13 312 131 28 6 4 14 6.7 315 25 7 39 4 151 38 12 3 2 15 7.5 945 36 24 182 20 378 188 50 8 6 16 6.7 1225 80 19 281 31 490 346 67 3 8 17 6.8 925 49 21 195 22 381 215 64 4 7 18 6.9 1372 119 36 286 32 549 413 103 3 7 19 7.7 900 30 19 211 23 360 242 21 6 8 20 7.4 1369 82 23 383 42 547 499 88 10 11 21 7.4 350 25 6 67 7 140 76 27 5 3 22 7.5 882 54 11 242 27 353 291 63 5 9 23 7.4 546 39 12 80 9 218 91 32 5 3 24 6.8 336 23 8 50 5 134 62 14 3 3 25 7 546 22 4 40 4 68 44 48 6 2 total dissolved solids (tds): different geological regions influence the concentration of tds due to differences in the solubility of minerals (who, 2004). as the residence time of groundwater in the geological formation increased, the tds and major ion concentrations are also increased (norris et al., 1992). based on who standards, the highest desirable limit for tds is 500mg/l and maximum permissible limit is 1500 mg/l. in the study area, during pre-monsoon the tds values exceeds maximum permissible limit at locations 6, 22 and 24. the remaining locations fall under the category of highest desirable limit at locations 3, 8, 12, 16, 20 and 25 and maximum permissible limit at locations 1, 2, 4, 5, 7, 9, 10, 11, 13, 14, 15, 17 18, 19, 21 and 23. during post-monsoon the groundwater quality has been changed as evidenced by the locations 6, 22 and 24 which are changed in to maximum 40 east afr. j. biophys. comput. sci., vol. 2, issue 1 permissible category from exceeding limit. the highest desirable limit category occurs at locations 3, 8, 12, 14, 16, 20 and 25 and maximum permissible limit category at 1, 2, 4, 5, 6 7, 9, 10, 11, 13, 15, 17 18, 19, 21, 22, 23 and 24. the classification of groundwater, according to davis and de wiest (1966), based on tds is given in table 3. table -3: classification of groundwater based on tds (davis and de wiest, 1966) tds (mg/l) water type samples (pre-monsoon) samples (post-monsoon) <500 desirable for drinking 3, 8, 12, 16, 20,25 3, 8, 12, 14,16, 20, 25 500-1000 permissible for drinking 1, 2, 5, 9, 10, 11, 13, 15, 18, 19, 23 1, 2, 5, 7, 9, 10, 11, 13, 15, 19, 21, 23, <3000 useful for irrigation 4, 6, 7, 14, 17, 21, 22, 24 4, 6, 17, 18, 22, 24 >3000 unfit for drinking and irrigation ---------- total hardness (th): the presence of carbonates and bicarbonates of calcium and magnesium, chlorides, nitrates and sulphates of calcium and magnesium cause total hardness in groundwater. according to sawyer and mccarty (1967), based on th, the groundwater is classified as soft (th<75 mg/l), moderately hard (th= 75-150 mg/l), hard (th= 150-300 mg/l) and very hard (>300 mg/l). spatial distribution of total hardness for pre and postmonsoon is shown in figure 3. during premonsoon no soft water occurred in the study area but moderate hard water was found at location no. 20. hard water mainly occurred in west and some eastern part of the study area at locations 1, 2, 3, 5, 8, 9, 10, 12, 13, 16, 23 and 25. very hard water occurred at locations 4, 6, 7, 11, 14, 15, 17, 18, 19, 21, 22 and 24. in post monsoon, the total hardness of the groundwater was remarkably changed. except at locations 6 and 22, which showed very hard water, all other groundwater samples were observed as hard water. the drinking water quality was evaluated by comparing with the specifications of th, tds and other parameters set forth by the world health organization and indian standards (table 4). calcium and magnesium: calcium and magnesium are abundantly occurred elements in natural waters in the form of bicarbonates, sulfate and chloride. ca concentrations were varying from 21 to 118 mg/l in pre-monsoon and 21 to 119 mg/l in post-monsoon. the desirable limit of calcium concentration for drinking water as per the standards of who (2004) is 75 mg/l. during pre-monsoon and post-monsoon, 84% of the groundwater samples were under desirable limit. only 16 % of the groundwater samples have crossed the desirable limit. the higher concentration of ca could cause abdominal ailments in humans and encrustation and scaling in pipes. magnesium content varied from 4 to 68 mg/l in premonsoon and 4 to 36 mg/l in post-monsoon. according to who standards, the desirable limit for mg is 50 mg/l which shows that 92% and 100% groundwater samples from the study 41 east afr. j. biophys. comput. sci., vol. 2, issue 1 area fell under the desirable category during pre-monsoon and post-monsoon respectively. table -4: parameter range who (2004) and isi (2009) standards for drinking purpose s.no water quality parameters who standards (2004) indian standard (isi 10500,2009) premonsoon range in the study area postmonsoon range in the study area most desirable limit max. allowable limit highest desirable max. permissible 1 ph 6.5 8.5 6.5-8.5 no relaxation 6.6-7.5 6.7-7.7 2 tds 500 1500 500 2000 350-1778 315-1372 3 th (as caco3) 100 500 200 600 71-495 71-445 4 ca 75 200 75 200 21-118 21-119 5 mg 50 150 30 no relaxation 4-68 4-36 6 na 200 200 48-462 39-383 7 k 12 5-51 4-42 8 so4 200 400 200 400 18-166 9-103 9 cl 200 600 250 1000 22-577 15-499 10 no3 40 50 45 no relaxation 1-10 2-10 sodium and potassium (na and k): the concentration of na in the study area varied from 48 to 462 mg/l in pre-monsoon and 39 to 383 mg/l in post-monsoon. according to who standards (200 mg/l) 40% and 28 % of the groundwater samples exceeded the maximum allowable limit during pre and post-monsoon respectively. water with high sodium content can be easily absorbed by soil which in turn determines the irrigation soil quality. high sodium concentration in the soils leads to development of an alkaline soil which results in alkaline hazard. the maximum allowable limit for k is 12 mg/l as per who standard but in pre-monsoon 68% of the groundwater samples exceeded the limit and during post-monsoon only 48 % of the samples exceeded the limit. the high concentration of k could be attributed to the dissolution of potash feldspar associated with charnockite in the study area. bicarbonate (hco3): the value of bicarbonate was observed from 140 to 711 mg/l and 68 to 549 mg/l during pre and post-monsoon respectively. mineral dissolution plays the key role for higher concentration of hco3 in groundwater (stumm and morgan, 1996) sulphate (so4): the sources, residence time and different geochemical process influence the concentration of so4. dissolution or weathering of gypsum and anhydrite minerals is the important geochemical process responsible for high concentration of so4 in groundwater. the so4 concentration in groundwater samples from the study area varied from 18 to 166 mg/l and 9 to 103 mg/l during pre and post-monsoon respectively. as per who standards, all groundwater samples were well within desirable limit of 200 mg/l in both the seasons. chloride (cl): the chloride content in groundwater might be originated from different 42 east afr. j. biophys. comput. sci., vol. 2, issue 1 sources such as intrusion of salt water, weathering, leaching of various rock types, domestic and industrial waste discharges (karanth, 1987). in the study area, the concentration of chloride ranged between 22 and 577 mg/l and 15-499 mg/l in which 40% and 36% of total water samples exceeded the most desirable limit of 200 mg/l set by who during pre and post-monsoon respectively. the excess of chloride in the water is usually taken as an index of pollution and considered as tracer for groundwater contamination (loizidou and kapetanios,1993). nitrate (no3): according to who, nitrate concentration in groundwater samples from the study area was within the prescribed limit of 50 mg/l in both the seasons. the values vary from 1 to 10 mg/l and 2-10 mg/l during pre and postmonsoon respectively. nitrate concentration in the study area could be attributed to discharges of sewage effluents and agriculture chemicals. corrosivity ratio: corrosion is basically an electrolytic process, which severely attacks and corrodes the metal surfaces. the rate at which corrosion proceeds depends upon a variety of chemical equilibrium reactions as well as upon certain physical factors like the temperature, pressure and velocity of flow (ayers and westcot, 1985). if the corrosivity ratio is less than 1, then the metal pipes can be used for transporting water, whereas pvc pipes must be used in areas where corrosivity ratio is more than 1. out of total water samplestested, only few locations at 5, 9, 12, 14, 17, 21, 22, 23 and 24 were exceeded the limit of 1 in pre-monsoon. during post-monsoon the corrosivity ratio of the groundwater samples was more than 1 at locations 4, 5, 13, 14, 17, 18, 22, 23 and 24. piper’s trilinear plot: the major cations and anions are plotted on piper diagram (piper, 1944) to assess the geochemical evolution of groundwater. this diagram is used to study the differences and similarities in the composition of groundwater and for classification of water types. the hydrochemical facies for the groundwater samples from the study area is shown in figure 4. during pre-monsoon two major facies types are present which are ca-nahco3 water type and na-cl water type. these water types suggest that the groundwater chemistry was controlled by a mixing process and evaporation process. in post monsoon also the major water types are ca-na-hco3 and nacl types. a few samples however were mixed ca-mg-cl type suggesting that same geochemical process was controlling the groundwater chemistry. 43 east afr. j. biophys. comput. sci., vol. 2, issue 1 86 figure4: us salinity and piper plot for pre-monsoon and post-monsoon suitability of groundwater for irrigation sodium adsorption ratio (sar): sar ratio is a measure of alkali or sodium hazard to crops. more na concentration in irrigation water can reduce permeability and free flow of air and water. this is due to exchange process by na ions adsorbed by the clay particle replacing the mg and ca ions (saleh et al., 1999; yidana, 2010). the sodium adsorption ratio is expressed as where all ionic concentrations are expressed in meq/l. 44 east afr. j. biophys. comput. sci., vol. 2, issue 1 the sar value varied from 2 to 12 (table 1 and 2) in both pre-monsoon and post-monsoon. table 5a and 5b illustrates sar classification of groundwater samples from the study area for both the season. during pre-monsoon 96% of groundwater samples were suitable for all types of crops and soil except for those crops sensitive to sodium. the remaining 4% of the ground water sample was suitable for coarse textured or organic soil with permeability. during postmonsoon 92% of the groundwater samples were suitable for all types of crops and soils except for those crops which were sensitive to sodium, and 8 % were suitable for coarse textured or organic soil with permeability. table5a: suitability of water for irrigation with different value of sar-premonsoon sar suitability of irrigation samples 1-10 suitable for all types of crops and soil except for those crops sensitive to sodium 96% 10-18 suitable for coarsed textured or organic soil with permeability 4% 18-26 harmful for almost all soil - >26 unsuitable for irrigation - table5b: suitability of water for irrigation with different value of sar-postmonsoon sar suitability of irrigation samples 1-10 suitable for all types of crops and soil except for those crops sensitive to sodium 92% 10-18 suitable for coarse textured or organic soil with permeability 8% 18-26 harmful for almost all soil - >26 unsuitable for irrigation - us salinity diagram (1995): the analytical data was interpreted using ussl diagram to assess the groundwater quality for irrigation purpose. figure 4 shows 60% samples were in c2-s1 and c3-s1 categories suggesting that the water can be used for irrigation activity in premonsoon. the remaining 40 % were in c3-s2 and c4-s2 indicating that groundwater is suitable for irrigational use with limited risk due to exchangeable sodium. in post-monsoon 56% of the samples belonged to c2-s1 and c3-s1 categories and 36 % samples were in c3-s2 category suggesting that the water can be used for irrigational purpose. the remaining 8% samples fell in c3-s3 category which shows high salinity and sodium hazard suggesting that water is not suitable for irrigation purpose. conclusions the geology and geomorphology of the study area comprises of charnockite of archaean age and buried pediments respectively. in the present study, interpretation of geochemical analysis of groundwater samples revealed that, th and tds values were found to be suitable for drinking purposes. based on th values very hard water occurred at locations 4, 6, 7, 11, 14, 15, 17, 18, 19, 21, 22 and 24. total dissolved solids in groundwater were less than 2000 mg/l in both the seasons. in some locations the sodium and potassium concentrations were 45 east afr. j. biophys. comput. sci., vol. 2, issue 1 higher than the prescribed limit corrosivity ratio of the groundwater samples was more than 1 at some sampling points suggesting that pvc pipe must be used in those areas. except for a very few locations sar valuewas less than 10 signifying the suitability of groundwater for irrigation purpose. based on ussl diagram, the dominant categories were c2-s1, c3-s1, c2-s1, c3-s1, c3-s2 in both pre and post-monsoon, suggesting that the groundwater is suitable for irrigational activities excepting a few locations which fall under the c3-s3 category indicating high sodium hazard. according to piper diagram most of the samples were classified as na-hco3 water type and na-cl water type in pre-monsoon and ca-na-hco3 and na-cl types in post-monsoon. the interpretation of these water types suggests that, mixing and evaporation processes are the two dominant geochemical processes in the study area. acknowledgements the authors are grateful to the head of the department of geology, presidency college, chennai, tamilnadu, india for all the facilities provided to continue the research work. references abderamane h., razack m. and vassolo s. 2013. hydrogeochemical and isotopic characterization of the ground water in the chari-baguirmi depression. republic of chad. environ. earth sci. 69: 2337– 2350 apha 1995. standard method for the examination of water and waste water, 16thed, washington d.c. ayers r.s. and westcot d.w. 1985. water quality for agriculture, irrigation and drainage, paper no. 29, rev.1, fao, rome, 174p. babiker i.s. mohamed m.a.a. and hiyama t. 2007. assessing groundwater quality using gis. water resour manag 21:699–715. burrough p.a. and mcdonnell r.a. 1998. principles of geographical information systems. oxford university press, oxford, p 333. davis s.n. and de wiest r.j.m. 1966. hydrogeology, vol 463. wiley, new york. furi w., razack m., alemayu t.a., ayenew t. and legesse d. 2011. fluoride enrichment mechanism and geospatial distribution in the volcanic aquifers of the middle awash basin, northern main ethiopian rift. j. afr. earth sci. 60: 315–327. jalali m. 2009. geochemistry characterization of groundwater in an agricultural area of razan, hamadan, iran. environ. geol. 56: 1479–1488. karanth k.r. 1987. groundwater assessment, development and management. tata mcgraw hill publishing company limited, new delhi. krishna kumar s., chandrasekar n., seralathan p., godson princes. and magesh n.s. 2011. hydrogeochemical study of shallow carbonate aquifers, rameshwaram island, india. environ monit assess. doi:10.1007/s10661-011-2249-6. krishna kumar s., logeshkumaran a., magesh n.s., godson p.s. and chandrasekar n. 2015. hydrogeochemistry and application of water quality index (wqi) for groundwater quality assessment, anna nagar, part of chennai city, tamil nadu, india. appl. water sci. 5: 335–343. loizidou m. and kapetanios e.g. 1993. effect of leachate from landfills on underground quality. sci total environ 128:69–81. doi: 10.1016/00489697(93)90180e. norris r.d. 1992. in-situ bioremediation of groundwater and geological material. a review of technologies, epa/600/r-93/124 (ntis pb93215564). piper a.m. 1944. a graphic procedure in the geochemical interpretation of water analysis. trans amer. geophys. union. 25: 914 – 923. ravikumar p. and somashekar r.k. 2013. a geochemical assessment of coastal groundwater quality in the varahi river basin, udupi district, karnataka state, india. arab. j. geosci. 6: 1855-1870. ryznar j.w. 1944. a new index for determining amount of calcium carbonate scale formed by a water. j. am. water. works assoc. 36: 472–486. saleh a., al-ruwaih f. and shehata m. 1999. hydrogeochemical processes operating within the main aquifers of kuwait. j. arid. environ. 42: 195– 209. sawyer g.n. and mccarthy d.l. 1967. chemistry of sanitary engineers, 2nd edn. mc graw hill, new york, p 518. senthilkumar s., aruna m., malathi d., sivakumar r. and gowtham b. 2014. hydrogeochemistry of mailam block of tindivanamtaluk, villupuram district, tamilnadu. j. appl. geochem.16 (1): 64-80. srinivasamoorthy k., vijayaraghavan k., vasanthavigar m., sarma v.s. and rajivgandhi r. 2011. assessment of groundwater vulnerability in mettur 46 east afr. j. biophys. comput. sci., vol. 2, issue 1 region, tamilnadu, india using drastic and gis techniques. arab. j. geosci. 4: 1215-1228. stumm w. and morgan j.j. 1996. aquatic chemistry. wiley, new york, p 1022. sujatha d. and reddy r.b. 2003. quality characterization of groundwater in the south eastern parts of the ranga reddy district, andhra pradesh, india. environ geol 44(5):570–576. ussl (united states salinity laboratory staff) 1995. classification of use of irrigation water, u.s; department of agriculture, circular, 969, washington. who (world health organization) 2004. guidelines for drinking water quality. 3rd edition, world health organization, geneva. yidana s.m. 2010. groundwater classification using multivariate statistical methods: southern ghana. j. afr. earth sci. 57: 455–469. . 47 cover v2.pdf (p.1) cover.pdf (p.1-2) slide number 1 blank page.pdf (p.2) table of contents vo 2.pdf (p.3-5) all articles vol 2.pdf (p.6-81) volume 2 issue 1_ 6 articles_4_3.pdf (p.6-91) 4_captive fish_anna results and discussion references 3_reproductive disorder 6_diet bredth_prof. nat 8_ground water_jeeva base boundary map was prepared using survey of india topo-sheets of the study area, and data such as rainfall, geomorphology, geology and land use were collected from central and state government agencies. during field study, groundwater samples were ... 10_ethnoveterinary following comments dagne et al_ challenging students’ performance through practical skills assessment.pdf (p.73-82) guideline to authors_ eajbcs.pdf (p.82-90) back cover.pdf (p.91) introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction east afr. j. biophys. comput. sci. (2023), vol. 4, issue. 2, 31-42 *corresponding author: email: kassayebalkew@gmail.com, +251 936211992 https://dx.doi.org/10.4314/eajbcs.v4i2.3s oreochromis niloticus belete berhanu1, kassaye balkewworkagegn1, 2*, natarajan pavanasam1 1department of aquatic sciences, fisheries and aquaculture, college of natural and computational sciences, hawassa university, p. o. box: 05, hawassa, ethiopia 2centre for aquaculture research and education (care), college of natural and computational sciences, hawassa university, p. o. box: 05, hawassa, ethiopia keywords: sex-reversal; methyl testosterone; mono-sex production; hapa; nile tilapia abstract the present study aimed at developing all-male nile tilapia using 17α-methyl testosterone (17α-mt) along with its growth and feed utilization performances. three days old nile tilapia fry were stocked in plastic jars with 5 l capacity installed in four fiber glass tanks. the fry were fed with 0, 30, 60, and 100 mg mt/kg diets for 30 days. later, the fry were shifted to hapas installed in a pond and then, reared for four months separately. the fish were fed with the control diet. the results showed that the highest male population (93.6%) was observed in the fish treated with a 60 mg mt/kg diet, while the lowest (82.6%) was observed in the fish treated with a 30 mg mt/kg diet. the results also showed that the fish fed with a 60 mg mt/kg diet had significantly higher mean body weight (24.1±1.40 g), specific growth rate (2.5±0.10%), feed conversion ratio (1.3±0.10), and protein efficiency ratio (0.63±0.11) than the untreated fish treated (control) group. in conclusion, a 60 mg mt/kg diet can be considered as an optimal and economically viable dose for nile tilapia sex reversal along with its optimum growth and feed utilization performances. introduction among several cultivable fish species, tilapia has been identified as the second most important aquaculture fish species in the world, particularly in the tropical and sub-tropical countries next to carp (el-sayed, 2006; dagne et al., 2013). it is also considered as one of the most important traded fish in the world (kyule et al., 2014; magbanua and ragaza, 2022). farmed tilapia production increased significantly from 383,654 tons in the 1990s to 4,514,615 tons of production in 2020 (fao, 2022). basically, for optimal production performance of the semi-intensive fish culture, high quality fish feed are the most preferred due to their good palatability and digestibility required for body maintenance, growth, reproduction and health (howlader et al., 2023). although nile tilapia has such good characteristics, its precocious and prolific reproduction and early sexual maturation of female has become one of the main challenges east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx effect of 17α-methyl testosterone on sex reversal and growth performance of nile tilapia, research article east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 31-42 32 for considering this species for commercial aquaculture (chakraborty and benerjee, 2012; munguti et al., 2014). this resulted in the reduction of growth rate at the onset of sexual maturation and the production of a large number of fry/fingerlings (munguti et al., 2014). considering the differential growth patterns of males and females, all-male nile tilapia production has been given better consideration as males are capable of showing a better growth rate and food conversion efficiency (chakraborty and banerjee, 2012). it is in this context, production of all-male populations of nile tilapia is vital for increasing fish production under low management practices (el-sayed, 2006). among the various techniques employed, hormonal sex-reversal has been considered as an effective method (ferdous and ali, 2011; jamila et al., 2017). even though it is the most important method, reports of different authors are not consistent (wahby and shalaby, 2010; celik et al., 2011; lakshmi, 2015). celik et al. (2011) reported that the efficiency of such a method can be affected by different environments, feeding rates, and feeding management, and overall production management. hence, the evaluation of such method in a specific production environment is crucial. thus, the main objective of this study was to find out an optimum dose of 17α-methyl testosterone on the proportion of nile tilapia male population along with growth performance and feed utilization efficiency of nile tilapia under a semi-intensive production system. materials and methods experimental setup the experiment was carried out at ziway fishery and other aquatic life research centre, ziway. the research centre is situated at 163 km southeast direction of addis ababa, the capital city of ethiopia. it is located at 7o52' to 8o8' n latitude and 38o40' to 38o56' e longitude, at an altitude of 1636 m above sea level. for this study, indoor and outdoor experimental setups were used. for the indoor experiment, four fibre glass tanks each with a size of 2000 ml were prepared. within each tank, three plastic circular shape jars with 5 l capacity were installed for hormone-treated feed trial experiments. for the outdoor experiment, 12 hapas with 1.5 m x 2 m x 1 m size were installed in a concrete pond. before installation of the hapas, the pond was dried for one week and then, refilled with water at depth of 90 cm. source of experimental fish and feed formulation sexually matured nile tilapia broodstock that measured 200 to 250 g body weight were selected from the holding tank of the ziway research centre and immediately transferred into hapas with 1.5 m x 2 m x 1 m size installed in a pond at a stocking density of 4 fish/hapas with a sex ratio of 1 male to 3 females for mating (ref.). from these hapas, newly hatched nile tilapia fry were collected and transferred in plastic bottles having 5 l water holding capacity for feed trial experiments. the experiment was conducted in triplicates with four treatments (i.e., 0, 30, 60, and 100 mg mt/kg of diets). fish diet was formulated by mixing 43% of fishmeal, 36% of niger cake, 10% of wheat bran, 7% of white corn flour, 2% of vitamins and mineral premix, and 2% of sunflower oil, having 38% of crude protein. later, the mixed ingredients was divided into four groups, in which the first one was not treated with 17αeast afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 31-42 33 methyl testosterone (0 mg mt/kg of diets) was used as a control diet, while the remaining three groups were treated with 30, 60 and 100 mg mt dissolved in 95% ethanol per kilogram diet and were used as tested diets. the control diet was also mixed with the same amount of ethanol without hormone. then, the diets were dried at room temperature for 24 hours and were stored in a refrigerator (celik et al., 2011). indoor and outdoor experiments immediately after hatching, 300 newly hatched fry collected from the hapas were transferred into 12 plastic bottles installed in 4 fiberglass rearing tanks for three days of acclimatization. later, after hatching 240 fry, 20 fry per plastic bottle, with an average body weight of 0.05 g were distributed in 12 plastic bottles having 5 l water holding capacity installed in four fiberglass rearing tanks in triplicates and reared for one month. to facilitate water circulation, the bottles were provided with small holes which were less than the size of the fry. the fry were, then, fed four times at 8:00, 12:00 and 16:00 and 18:00 hours a day with 0 mg mt, 30 mg mt, 60 mg mt and 100 mg mt/kg diets having 38% crude protein for 30 days at 20% of their body weight (shamsuddin et al. (2012). early morning, uneaten food and faecal matter were removed daily using siphoning. oxygen was provided to each tank using aerators. after 30 days of treatment, total body weight of the all fry were measured and then transferred and stocked in hapas with a size of 1.5 m x 2 m x 1 m installed in the grow-out pond at an average stocking density of 18 fish per hapa and reared for four months. during this time, the fish were fed three times at 9:00, 13:00 and 17:00 hours a day with a control diet at 10% of their body weight (mugo-bundi (2013). the overall research procedure was approved by the research committee of hawassa university and thus, all applicable international and national guidelines for the care of animals and use of animals were followed by the authors. data collection and sex determination every 15 days (2 weeks) of interval, individual body weight and body length of hormonetreated fish stocked in plastic bottles were recorded early morning. the mortality of the fry was recorded daily. similarly, every 15 days of interval, individual body weight and body length of the experimental fish stocked in hapa were recorded. at the end of the experiment (on week 16, i.e. harvesting week), the final body weight and body length of all the fish were recorded. in addition, the sex of each fish was identified based on external and internal observation of the sex organs of the fish. iodion solution as dye was used to differentiating the sex of the fish when the secondary sexual characters were found difficult to differentiate. ten fish per treatment were dissected and the morphology of the gonads was examined and recorded. water quality parameters such as water temperature, ph, dissolved oxygen, conductivity, and total dissolved solid were measured using potable multi-parameter kit. following final body weight and length measurements, calculation of growth parameters were performed using the following formula described by eyo et al. (2013). i. calculation of growth and feed utilization efficiency: o body weight gain (bwg) = final body weight (fbw) – initial body weight (ibw) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 31-42 34 o daily growth rate (dgr) = weight gain/number of experimental days o specific growth rate (sgr % per day) = ((lnfbwlnibw)/ number of days) *100 ii. calculation of feed utilization efficiency:  food conversion ratio (fcr) = amount of dry food intake/weight gain  protein efficiency ratio (per) = weight gain/amount of crude protein iii. calculation of survival rate, condition factors and fish yield (put ref. for each formula):  survival rate (sr%) = number of harvested fish/number of stocked fish *100  condition factor (cf) = final body weight/ (length3) x 100  total production = (no. of fish harvested × fbw/area of rearing place) x10000 m2 x production cycle statistical analysis based on the data recorded and calculated values basic statistics were computed using spss 20 version after the data were tested for normality and equal variance. the statistical significance among growth parameters and sex ratio of fish fed with different test diets were computed using one-way anova (analysis of variance) in the spss. significance was assigned at a 5% level of probability. for between mean treatments significant variation, was performed using tukey hsd standardized range test α = 0.05 level of significance as described according to el greisy and el-gamal (2012). results indoor growth and survival rate of fry the mean body length and weight of fry at stocking and after 30 days of hormone treatment of all groups are presented in table 1. the initial mean body length and body weight of fry were the same (1.3 cm and 0.05 g). after one month of rearing, the length of fry ranged from 3.3±0.12 cm (30 mg mt/kg diet) to 3.7±0.30 cm (60 mg mt/kg diet) while the mean body weight of the fry ranged from 0.81±0.18 g (60 mg mt/kg diet) to 0.84±0.13 g (control diet). additionally, the survival rate of the fish in different treatments was high, ranging from 88.2±2.1 to 92.2±1.6%. in all cases, there was no significant (p > 0.05) difference in survival rates among the treatments (table 1). table 1: mean body size parameters with standard error (mean + se) of fry at stoking and after 30 days of oral administration with different doses of 17α-methyl testosterone (17α-mt). parameters treatments 0 mg mt/kg diet 30 mg mt/kg diet 60 mg mt/kg diet 100 mg mt/kg diet initial body length (cm) 1.3±0.37 1.3±0.37 1.3±0.37 1.3±0.37 initial body length (g) 0.05±0.02 0.05±0.02 0.05±0.02 0.05±0.02 body length (cm) after 30 days of treatment 3.4±0.20a 3.3±0.12a 3.7±0.30a 3.4±0.20a body weight (g) after 30 days of treatment 0.84±0.13a 0.82±0.20 a 0.81±0.18a 0.82±0.15a survival rate (sr%) 90.2±1.4a 90.2±1.2a 92.2±1.6a 88.2±2.1a note: values with the same letter across a row are not significantly different (p > 0.05) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 31-42 35 effects of mt on sex ration the sex ratio of nile tilapia fed with hormonetreated diets is presented in table 2. the gonad differentiation of fish fed with the mt-treated diets gave a higher male proportion than fish fed with the control diet. the maximum male population (93.6%) was observed for the fish fed with a 60 mg mt/kg diet followed by a 100 mg mt/kg diet (86.7%), while the lowest male population was observed for the fish fed with the control diet (54.3%). the results showed that the fish fed with a 60 mg mt/kg diet produced significantly (p < 0.05) higher male population than the other groups while the fish fed with the control diet produced the least significant. table 2: percentage of male population of nile tilapia produced after oral administration with different doses of 17α-methyl testosterone (17α-mt). dose of mt male % p value 0 mg mt/kg (control) diet 54.3a 0.35 30 mg mt/kg diet 82.6b < 0.001 60 mg mt/kg diet 93.6c < 0.001 100 mg mt/kg diet 86.7b 0.005 note: values with the same letter across column are not significantly different (p > 0.05) outdoor growth performance the different growth parameters such as mean body weight gain, daily growth rate, and specific growth rate, and feed utilization efficiency such as feed conversion ratio and protein efficiency ratio of nile tilapia fed with different doses of mt-treated diets are presented in table 3. the results showed that the highest mean body weight (24.1±1.4 g) and body weight gain (24.0±1.2 g) were recorded in the fish fed with 60 mg mt/kg diet followed by 100 mg mt/kg diet (19.1±0.8 g and 19.0±0.2 g), while the lowest (14.3±1.8 g) and 14.2±0.1 g) was observed for the fish fed with a control diet, respectively. similarly, the highest mean body length (11.1±1.2 cm) was observed for the fish fed with 60 mg mt/kg diet, followed by 10.2±1.2 cm mean body length of fish fed with100 mg mt/kg diet, while the lowest (9.1±0.79 cm) was observed for the fish fed with control diet (table 3). the results also showed that the fish fed with hormone treated diets had significantly (p < 0.05) higher final mean body weight, in which the fish fed with 60 mg mt/kg diet had significantly (p < 0.05) higher final mean body weight, and mean weight gain than at least from the fish fed with the control diet. figure 1 also showed the growth trend of body weight of the fish, in which fish body weight increased steadily for the first six weeks, and then, the rate of growth slightly increased. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 31-42 36 table 3: mean growth parameters with standard error (mean + se) of nile tilapia treated with different doses of 17α-methyl testosterone (17α-mt). parameters treatments 0 mg mt/kg diet 30 mg mt/kg diet 60 mg mt/kg diet 100 mg mt/kg diet initial body length (cm/fish) 1.3±0.37a 1.3±0.37a 1.3±0.37a 1.3±0.37a initial body weight (g/fish) 0.05±0.02a 0.05±0.02a 0.05±0.02a 0.05±0.02a final body length (cm/fish) 9.1±0.79a 9.6±1.03a 11.1±1.19a 10.2±1.17a final body weight (g/fish) 14.3±1.84a 18.3±2.46b 24.1±1.38b 19.1 ±0.79b body weight gain (g/fish) 14.2±0.02a 18.2±0.02b 24.0±0.21c 19.0±0.21b daily growth rate (g/fish/day) 0.12±0.01a 0.15±0.01ab 0.20±0.1b 0.18±0.01ab specific growth rate (%/fish/day) 2.2±0.2a 2.3±0.01ab 2.5±0.1b 2.4±0.1ab note: values with the same letter across rows are not significantly different (p > 0.05) the results also showed that the fish fed with hormone treated diets had significantly (p < 0.05) higher final mean body weight, in which the fish fed with 60 mg mt/kg diet had significantly (p < 0.05) higher final mean body weight, and mean weight gain than at least from the fish fed with the control diet. figure 1 also showed the growth trend of body weight of the fish, in which fish body weight increased steadily for the first six weeks, and then, the rate of growth slightly increased. figure 1: the trend of mean weight of different group of nile tilapia reared in hapa installed in pond, where w0 to w16 are rearing times in weeks at two weeks interval, w0 is for initial week, i.e. week zero, while w16week sixteen, i.e. harvesting week east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 31-42 37 similarly, the results revealed that the highest mean daily growth rate (0.20±0.1 g/day) and specific growth rate (2.5±0.01%/day) were recorded for the fish fed with 60 mg mt/kg treated diet than the other groups of fish fed with different level of mt. they were significantly different (p < 0.05) at least from the lowest mean daily growth rate (0.12±0.01 g/day) and specific growth rate (2.2±0.02%/day) of the fish fed with the control diet. the trend of daily growth rate and specific growth rate fluctuated as the rearing period increased (figures 2 and 3). figure 2: the trend of daily growth rate of different group of nile tilapia reared in hapa installed in pond figure 3: the trend of specific growth rate of different group of nile tilapia reared in hapa installed in pond, where w2 to w16 are rearing times in weeks, in which fish sampling wars taken at two weeks interval, w2 was the first sampling times in which fish were sampled after two weeks rearing, while w16week sixteen, i.e. harvesting week. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 31-42 38 feed utilization efficiency and condition factor and weight-length relationship the mean values of feed utilization efficiency parameters and condition factors of nile tilapia fed with a control diet and mt-treated diets are presented in table 4. the food conversion ratio (fcr) of different fish fed with different levels of mt ranged from 1.3±0.1 to 2.3±0.1, while from 0.37±0.1 to 0.63±0.11 for protein efficiency ratio (per). the best fcr and per were obtained for the fish fed with a 60 mg mt/kg diet and were significantly (p < 0.05) different at least from the fish fed with the control diet. the condition factor of nile tilapia fed with control, 30 mg mt, 60 mg mt and 100 mg mt/kg diets were similar and ranged from 1.8±0.12 to 2.1±0.17. according to cube law, the ‘b’ values for all groups of fish are in a good condition. the ‘b’ values ranged from 2.8±0.16 to 2.9±0.14.the results showed that both futon condition factor and weight-length relationship parameters were no significant differences among groups (table 4). table 4: mean feed utilization efficiency, condition factor, survival and total production with standard error (mean + se) of nile tilapia treated with different doses of 17α-methyl testosterone (17α-mt) parameters treatments 0 mg mt/kg diet 30 mg mt/kg diet 60 mg mt/kg diet 100 mg mt/kg diet food conversion ratio 2.3±0.1a 1.8±0.3b 1.3±0.12b 1.8±0.13b protein efficiency ratio 0.37±0.1a 0.48±0.12a 0.63±0.11a 0.50±0.20a fulton condition factor 1.9±0.13a 2.1±0.17a 1.8±0.14a 1.8±0.12a weight-length relationship 2.8±0.16a 2.9±0.21a 2.9±0.18a 2.9±0.14a survival rate (sr%) 100±0.00a 100±0.00a 97.9±0.12a 100±0.00a total production (tp kg/ha/y) 2574.3±52.1a 3294.6±42.6b 4338.7±73.2c 3438.2±63.6b note: values with the same letter across row are not significantly different (p > 0.05) survival rate of fish and fish production the survival rate and total production of all the nile tilapia groups are presented in table 4. the survival rates of different nile tilapia groups were similar, ranging from 97.9±1.2% to 100±0.0%, while the total productions of different groups ranged between 2574.3±52.1 kg/year/ha and 4338.7±73.2 kg/year/ha. the fish fed with a 60 mg mt/kg diet had significantly higher total production at least from the fish-fed with the control diet. the results revealed that as the amount of mt dose increased from 60 mg mt/kg to 100 mg mt/kg diet the total fish production decreased (table 4). water quality parameters the different water quality parameters (ph, temperature, dissolved oxygen, total dissolved solid and conductivity) recorded during the experimental periods for both indoor and outdoor experiments are presented in table 5. the results of the indoor experiment showed that the different water parameters across treatments were similar. the values of temperature ranged from 24.0±0.3 °c to 24.4±0.5 °c, ph ranged from 7.6±0.4 to 7.8±0.6 east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 31-42 39 and dissolved oxygen from 3.6±0.3 mg/l to 3.8±0.7 mg/l. the values of total dissolved solids and conductivity also ranged from 448.6±3.4 mg/l to 451.1±3.2 mg/l and from 592.4±2.6 μs/cm to 594.9±2.7 μs/cm, respectively. however, none of the water quality parameters were significantly different among the treatments. for outdoor experiments, the results showed that the mean values of all water quality parameters recorded during the experimental period were optimal (28.5±1.1 °c for temperature, 8.7±2.0 for ph, 8.7±1.3 mg/l for dissolved oxygen, 543.3±3.5 mg/l for total dissolved solid and 721.4±5.27 μs/cm for conductivity). table 5: mean values of different water quality parameters with standard error (mean ± se) recorded during indoor and outdoor experiments. water quality parameters indoor experiment outdoor experiment treatments 0 mg mt/kg diet 30 mg mt/kg diet 60 mg mt/kg diet 100 mg mt/kg diet temperature (°c) 24.4±0.5a 24.3±0.4a 24.3±0.4a 24.0±0.3a 28.5±1.1 ph 7.7±0.3a 7.7±0.4a 7.8±0.6a 7.6±0.4 a 8.7±2.0 dissolved oxygen (mg/l) 3.6±0.3a 3.6±0.8a 3.8±0.5a 3.8±0.7a 8.7±1.3 total dissolved solid (mg/l) 450.7±3.9a 448.6±4.7a 451.1±4.1a 449.6±5.2a 543.3±3.5 conductivity (μs/cm) 593.6±3.4a 594.9±2.7a 592.4±2.6a 593.9±3.7a 721.4±5.2 note: values with the same letter across raw are not significantly different (p > 0.05).\ discussion and conclusions this study demonstrates that the application of 17α methyl testosterone at 30, 60, and 100 mg per kg diets produced a higher male population and growth performance than fish fed with untreated diet. among the hormone-treated diets, the fish fed with 60 mg mt/kg diet produced a significantly higher male population and body growth (p < 0.05) than the other groups. this result agreed well with the reports of el-greisy and gamal (2012) who reported a significantly higher male population using 60 mg mt/kg diet than 40 and 80 mg mt/kg diets. this result also coincides well with the results of celik et al. (2011) and shamsuddin et al. (2012) who reported 93.7% and 95% male population, using 60 mg mt/kg diet treated for 28 and 21 days, respectively. a similar result was reported by ferdous and ali (2011) who observed a maximum (94.3%) male population using a 60 mg mt/kg diet. these results are in line with the findings reported by marjani et al. (2009) in which higher growth performance of fish was obtained after hormone treatment. the present results also showed a higher male population (93.6%) for 60 mg mt/kg diet than the report of abdul (2007) (89%) and asad et al. (2010) (68%) for the same mt doses. on the other hand, the results of the present study showed a relatively lower male population as compared with 99-100% for fish treated with 60 mg mt/kg diet (vera–cruz and mair, 1994; smith and phelps, 2001). such differences could be due to differences in management practices. as also indicated by lakshmi (2015) and sourav (2016) such differences in male population could be due to factors such as the level of hormone in the diet, feeding and feeding frequency, water quality parameters, treatment duration, size at which the fry is selected for experimentation and stocking density. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 31-42 40 different doses of mt resulted in the different growth rates of nile tilapia in which fish group treated with a 60 mg mt/kg diet showed significantly higher mean body weight, body weight gain, daily growth rate, and specific growth rate of nile tilapia than the other groups. this result is in agreement with the report of pechsiri and yakupitiyage (2005) and opiyo et al. (2014), who observed optimal growth performance of fish when treated with 60 mg mt/kg diet. also, the results of the present study showed that the fish treated with mt treated diets had significantly higher feed utilization efficiencies than fish treated with control diet. statistically, the fish fed with a 60 mg mt/kg diet had the best feed utilization efficiency in terms of feed conversion ratio and protein efficiency ratio. this implies that 60 mg mt/kg diet promotes better growth performance, better feed utilization in fish as also reported by mugo-bundi (2013). the significant growth performance and feed utilization efficiency of fish fed with mt/kg diets agreed well with the findings of howerton et al. (1992) and varadaraj et al. (1994) who reported a higher growth rate in o. mossambicus fed with mt treated diet than the fish fed untreated diet. the present results also indicated that the fish treated with 60 mg mt/kg diet for 30 days showed maximum growth performance and feed utilization efficiency than the other groups, and further increase or decrease of hormone dose do not have much influence on growth and feed utilization efficiency in fishes as it seems optimal dose. this result also coincides with the work of lakshmi (2015) who reported faster growth and better feed utilization of nile tilapia when treated with a 60 mg mt/kg diet. el-greisy and el-gamal (2012) also reported higher growth and feed utilization efficiency in fish treated with 60 mg mt/kg diet than 40 and 80 mg mt/kg diets. this implies that a 60 mg mt/kg diet is an optimum dose of mt hormone for optimal production of male population, better growth and feed utilization efficiency and can be considered as an optimal dose for nile tilapia sex-reversal under the current production management. on the other hand, the condition factor of all groups of nile tilapia were similar implying that condition factors were not influenced by mt doses. as stated by ayode (2011), the fish from all the treatments showed isometric growth, implies that all the groups were in good condition.. the present work also revealed that nile tilapia followed the cube law completely in all groups of fish in which their values were close to the theoretical value (b = 3). the length-weight relationship was found to be in a linear form conforming to the general formula expressing the relationship between the length and weight of fishes. this could be due to the fact that the length-weight relationship of fish varies depending upon the condition of life in the aquatic environment (ighwel et al., 2011), but it is an important tool that gives information on the growth pattern of animals. in conclusion, 60 mg mt/kg diet can be considered as an optimal dose for nile tilapia sex reversal along with its optimum growth and feed utilization performances. authorship contribution statement berhanu b, workagegn kb, pavanasam n: conceptualization, methodology development, visualization, data analysis and writing up of the manuscript. workagegn kb, and p natarajan supervision, validation, formal analysis, writing, reviewing and editing of the manuscripts acknowledgments the authors would like to acknowledge noradhawassa university project for the financial support. the authors also acknowledge the staff of ziway fishery research centre for their technical assistance. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 31-42 41 references abdul m. 2007. effect of androgen on the sex reversal, growth and meat quality of tilapia, oreochromis niloticus. ph.d. thesis. university of agriculture, faisalabad, pakistan. asad f., ahmed i., saleem m. and iqbal, t. 2010. hormonal masculinization and growth performance in nile tilapia (oreochromis niloticus) by androgen administration at different dietary protein levels. intl. j. agric biol.,12(6):939-943. ayode a.a. 2011. length-weight relationship and diet of african carp labeo ogunensis in asejire lake southwestern nigeria. j fisheries and aquatic sci., 6:472-478. celik i., guner y. and celik p. 2011. effect of orallyadministered 17a methyl testosterone at different doses on the sex reversal of the nile tilapia (oreochromis niloticus, l.). j anim vet adv, 10 (7):853-857. chakraborty s.b., banerjee s. 2012. comparative growth performance of mixed sex and monosex nile tilapia at various stocking densities during cage culture. recent res. sci. technol., 4 (11):46-50 dagne a., degefu f. and lakew a. 2013. comparative growth performance of monosex and mixed sex nile tilapia (oreochromis niloticus l.) in pond culture system at sebeta, ethiopia. int. j. aquaculture, 3: 30-34. el-greisy z.a. and el-gamal a.e. 2012. monosex production of tilapia, oreochromis niloticus using different doses of 17α-methyltestosterone with respect to the degree of sex stability after one year of treatment. egypt j aquat res, 38:59-66. el-sayed a.f. 2006. tilapia culture. cabi publishing, cab international, wallingford, oxfordshire, uk. eyo v.o., ekanem a.p., eni g.e., asikpo p., jimmy u. 2013. comparative study of growth performance, food utilization and survival of hatchery bred and wild collected fingerlings of african catfish c. gariepinus. gr. j. of ocea. & marine science,1:110. fao, 2022. fishstat, fishery statistical time series: aquaculture production 1950–2020. fao, rome ferdous z. and ali m.m. 2011. optimization of hormonal dose during masculinization of tilapia (oreochromis niloticus) fry. j. bangladesh agril. univ., 9 (2): 359–364. howlader s., sumi k.r., sarkar s., billah s.m., ali m.l., howlader j. and shahjahan m. 2023. effects of dietary replacement of fish meal by soybean meal on growth, feed utilization, and health condition of stinging catfish, heteropneustesfossilis. saudi j biol sci. 30(3):103601. howerton r.d., okimoto d.e. and grau e.g. 1992. the effect of orally administrated 17alpha methyl testosterone and tri-iodothyronine on growth and proximate body composition of sea water adapted tilapia (oreochromis mossambicus). aqua. fish. manage, 23:123-128. ighwela k.a. and ahmed a.b. 2011.condition factor as an indicator of growth and feeding intensity of nile tilapia fingerlings (o. niloticus) fed on different levels of maltose. a-e j. of agriculture and environmental sciences, 11:559-563. jamila t.a. and rajagopalasay c.b. 2017. manual on freshwater finfish and shellfish breeding and hatchery management. fisheries college and research institute, tamilnadu fisheries university, india. lakshmi d.k. 2015. production of all male nile tilapia (oreochromis niloticus) using sex reversal technique. msc.thesis. fisheries science in fish biotechnology to the tamil nadu fisheries university, india. kyule d.n., yongo e., opiyo m.a., obiero k., munguti j.m., charo-karisa h. 2014. fish product development and market trials of fish and fish products in kenya: a case study of kirinyaga and meru counties. livest. res. rural. dev., 26:6-13. marjani m., jamili s., mostafavi p.g., ramin m. and mashinchian a. 2009. influence of 17-alpha methyl testosterone on masculinization and growth in tilapia (oreochromis mossambicus). j fish aquat sci, 4:7174. magbanua t.o. and ragaza j.a. 2022. systematic review and meta-analysis of the growth performance and carcass composition of nile tilapia (oreochromis niloticus) fed dietary copra meal. front. sustain. food syst. 6:1025538. mugo-bundi j., oyoo-okoth e., ngugi c.c., manguyalusega d., rasowo j. and chepkirui b.v. 2013. utilization of caridina nilotica (roux) meal as a protein ingredient in feeds for nile tilapia (oreochromis niloticus). aquac. res., 2:1-12. munguti j.m., mugiranea j.k., ogello e.o. 2014. an overview of the kenyan aquaculture sector, current status, challenges and opportunities for future development. fish aquatic sci,17:1-11. olurin k.b. and aderibigbe o.a. 2006. length-weight relationship and condition factor of pond reared juvenile oreochromis niloticus. world j. zool.,1 (2):82-85. opiyo m.a., githukia c.m., munguti j.m. and charokarisa h. 2014. growth performance, carcass composition and profitability of nile tilapia (o. niloticus l.) fed commercial and on-farm made fish feed in earthen ponds. int. j. fish. aquat. stud., 1:12-17 east afr. j. biophys. comput. sci. 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(2024), vol. 5, issue 1, 25-39 *corresponding author: 1department of biology, hawassa university, hawassa, ethiopia, p.o. box-05, 2department of aquatic sciences, fisheries and aquaculture, hawassa university, hawassa, keywords: actinomycetes; aantibacterial activity; disk diffusion methods; hawassa; pathogens abstract in recent years, antimicrobial resistance has surged significantly in developing countries, becoming a major public health concern. with nearly all bacterial pathogens developing multidrug resistance to commonly used antibiotics, there is an urgent need to discover novel drugs to tackle this challenge. actinomycetes are considered as one of the most diverse groups of filamentous bacteria capable of thriving into different types of ecological niches due to their bioactive potential. therefore, this study was aimed at isolation and characterization of actinomycetes from 20 soil samples that were collected from different sites of hawassa city, southern ethiopia. the actinomycetes were isolated using serial dilution followed by spread plate techniques and antimicrobial activity screening done using modified agar disc diffusion method. actinomycete isolation agar (aia) was used to isolate actinomycetes. a total of twenty nine different actinomycetes, identified as ab1-ab29, were isolated and differentiated based on their variations in colony morphology and mycelial structure. using modified agar disk diffusion methods, their secondary metabolites were assessed for antibiotic activities on e.coli, salmonella typhi, klebsiella pneumoniae, staphylococcus aureus and shigella boydii. moreover, actinomycete isolates with broad spectrum activity were also tested against methicillin resistant staphylococcus aureus (mrsa) using modified agar disk diffusion methods. out of 29 isolates, 19(65.5%) actinomycetes showed antimicrobial activity against selected bacterial pathogens. most of the isolates (84.2%) showed good antimicrobial activity against salmonella typhi and yet significantly lower than the control drug ciprofloxacin. maximum zone of inhibition was 29.2mm observed against s.typhi. as the result indicates the actinomycetes isolates showed higher inhibition zone against gram negative bacteria than gram positive bacteria. the study indicated that soils of hawassa may have potential group of actinomycetes with broad spectrum antimicrobial activity. it is therefore recommended that combining several molecular analysis methods, such as dna reassociation and pcr-based fingerprinting techniques, could greatly enhance our understanding of the overall genetic diversity of soil actinomycetes obtained in this study. introduction antibiotics are substances normally of low molecular weight capable of inhibiting or slowing the growth of pathogenic microorganisms. they are often secondary metabolite produced by microorganisms and seem to have no definite role in the growth of the cell source. microorganisms produce antibiotics normally during their late log phase of growth until their stationary phase. one of their key benefits to the source organism is said to be their ability to inhibit the growth and survival of other microorganisms in the same east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs isolation and characterization of antibiotic producing actinomycetes from soils of hawassa, southern ethiopia email: keshamo78hope@gmail.com, +25191 6831673 https://dx.doi.org/10.4314/eajbcs.v5i1.3s alazar ergena keshamo2*, abayneh agena1and zufan bedewi1 research article east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 26 environment in nature hence providing the source with a competitive advantage. antibiotic producing microorganisms can then compete with others and survive in nature for a long time (onlamoon, 2008). antimicrobial compounds are produced by various living organisms such as bacteria, fungi, and plants primarily as a defense mechanism against competing microorganisms. out of these numerous groups of organisms that produce antimicrobial agents, the actinomycetes are the most capable and well-studied candidate (gebreselema et al., 2013). actinomycetes are slow-growing, gram-positive bacteria that are characterized by a high guanine-cytosine (g&c) content, ranging from 55% to 75% (ningthoujam et al., 2009). they resemble fungi because of their filamentous appearance and spore production property and bacteria because of the presence of peptidoglycan in their cell wall and possession of flagella (mythili and das, 2011). actinomycetes are inexhaustible producers of antimicrobial agents (atta et al., 2011). actinomycetes are estimated to contribute around 45% of all bioactive microbial metabolites discovered to date, totaling approximately 23,000 (berdy, 2005). the secondary metabolites obtained from the class actinomycetes are of special interest because of their versatile anti-bacterial, anti-fungal, antioxidant, anti-tumor and anti-viral. among actinomycetes, streptomyces species produce around 7,600 compounds. since most of these secondary metabolites produced by streptomycetes are promising and powerful antibiotics, they are the primary antibioticproducing organisms exploited by pharmaceutical industry (sudha et al., 2015). they are responsible for the formation of more than 60 % of known antibiotics, further 15 % are made from a number of related actinomycetes, actinomadura, micromonospora, streptoverticillium, and thermo actinomycetes (jensen et al., 2007; ramesh et al., 2009). the emergence of resistance to the commercially available antibiotics and multidrug-resistant pathogenic bacteria are issues of extreme concern in present time for the whole human community. due to these issues, there is rapid spread of infectious diseases leading to illness and death especially among the aged and immune-compromised patients (hong et al., 2009). to overcome this situation the discovery of novel drugs with lesser side effects is need of present time. natural materials like soils are commonly preferred in researches based on the notion that several samples collected from several geographic locations are more likely to yield novel dwelling microorganisms and therefore confidently, different secondary metabolites are exploited as a result of the associated geographical variation. besides, the attempt of isolation and characterization of microorganisms from relatively unknown or unstudied areas is promising to identify additional and new microbes or their bioactive substances (moncheva et al., 2002). in ethiopia, a few studies showed the presence of antibiotic producing microorganisms from different ecosystems. biniam (2008) isolated antimicrobial producing actinomycetes from hora and chitu lakes. based on a research conducted by moges (2009), antibiotic producing thermophlic actinomycete can be isolated from a mushroom compost. atsede and fassil (2018) also isolated and screened antibiotic producing actinomycetes from soil east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 27 collected from the rhizosphere of plants and agricultural soils of ethiopia. nevertheless, there is no previous study conducted or scientific report made on antibiotic producing microorganisms from soil samples collected in hawassa city. therefore, the present study aimed to isolate and characterize antibioticproducing actinomycetes from soil samples of hawassa, southern ethiopia. materials and methods description of the study area the study was conducted in hawassa city. it is located 275 km away from addis ababa, the capital city of ethiopia. it is located at 70’ 03’’ latitude and 80’29” east and lies at an altitude of 1708 m above sea level. the city has a total area of 15,720 hectares and the city administration of hawassa consists of 8 sub cities and 32 kebeles. the city experiences a sub humid type of climate having an average annual temperature of about 20.3ocand mean annual precipitation of about 933.4 mm (hawassa city administration, 2007) collection of soil samples twenty (20) samples of soil were collected from four different sites of hawassa city namely: main campus (5), monopol (5), mount tabor (5) and mount alamura (5). two hundred grams of soil samples were taken from a depth of 1116 cm from the soil surface using sterile spoon (chaudhary et al., 2013). the samples were collected and placed in dry, clean, sterile polyethylene bags and transported aseptically to microbiology laboratory of the department of biology, hawassa university where the entire research work was conducted. the collected samples were labeled with details such as: name of collection site, date of collection and ph of soil. the ph of soil was measured before collecting the soil samples. the collected soil samples were desiccated under ambient conditions for a week to reduce gram negative bacteria (oskay et al., 2004). the soil samples from sterile plastic bag were grinded using sterile mortar and pestle and sieved aseptically using 250 µm pore size mesh to remove small pieces of stones and organic matter. the samples were then placed in polyethylene bags to avoid external contamination and kept in refrigerator at 4oc until used. isolation and cultivation of actinomycetes from each sample, 1g of soil sample was added in the test tube containing 10 ml distilled sterile water and shaken well using vortex mixer for 3 minutes and serially diluted by using serial dilution method up to 10-7. from these tubes or stock cultures, different titration and dilutions were prepared. accordingly, 1 ml of the stock culture was used to prepare the final volume of 10-1, 10-2, 10-3, 10-4, 10-5, 10-6 and 10-7 by serial dilution method. thereafter 0.1 ml of the suspension from 10-3, 10-5, and 10-7 was taken and aseptically spread onto actinomycete isolation agar (aia) medium (millipore, and sigma, germany) by applying spread plate technique and incubated at 30°c for 7 d. to get pure colonies, each colony were sub cultured by streaking on nutrient agar. the pure colonies were isolated and identified by the color of hyphae, colony morphology and the presence or absence of aerial and substrate mycelium (reddy et al., 2011). after incubation, the slants containing pure actinomycetes isolates were preserved at 4°c for the further studies. east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 28 screening of actinomycetes for antimicrobial activity test microorganisms antimicrobial properties against selected microorganisms acquired from the ethiopian health and nutrition research institute (ehnri) and hawassa university referral comprehensive specialized hospital were investigated in vitro. the test bacteria used for primary screening were staphylococcus aureus, escherichia coli, klebsiella pneumonia, shigella boydii and salmonella typhi. methicillin-resistant staphylococcus aureus (mrsa) (clinical isolate) which was provided by hawassa university referral comprehensive specialized hospital was also used for secondary screening. primary screening of the isolates by disc diffusion method antimicrobial screening was done using disc diffusion method as described by kirby bauer (1979). the stocked actinomycetes isolates were resuscitated by sub-culturing on nutrient agar plates. the colony was then picked and inoculated into 5ml nutrient broth and incubated at 30oc for 10 days. thereafter, the prepared culture was standardized to 0.5 mcfarland turgidity standard using the spectrophotometer (optical density of 1.0 at 625 nm) by adding sterile distilled water to obtain the desired cell density of 1.5 x 108 (cell/ml) (clsi, 2012). paper discs (6 mm in diameter) were prepared from whatman no 1 filter papers and sterilized by autoclaving at 121oc, 15psi for 15 minutes (ngeny et al., 2013). the disc (6 mm in diameter) was soaked with 15μl of the 7d old culture broth and properly positioned on mueller hinton agar inoculated with the test isolates. standard antibiotic (ciprofloxacin) was used as a positive control and filter paper disc soaked with sterile distilled water was used as a negative control. they were then incubated at 37oc for 24 hours. the isolates with antimicrobial activities were identified by measuring the inhibition zone in millimeters (mm) using a ruler. the absence of growth or a less dense growth of test bacteria near the disc was considered as positive for production and secretion of antibacterial metabolite by the isolates (kekuda et al., 2010). secondary screening of the isolates based on the zone of inhibition in primary screening, actinomycete isolates that have broad spectrum of inhibitory activity were further assessed against methicillin resistant s. aureus (clinical isolate). antimicrobial activity of the secondary metabolites that had broad spectrum activity in primary screening was determined following kirby bauer disk diffusion method (brown, 2009). sterile paper discs, immersed for 30 minutes in one-week-old actinomycetes broth cultures, were used to inoculate actinomycetes on muller hinton agar (mha) media seeded with methicillin resistant staphylococcus aureus (mrsa) (clinical isolate). the petri dishes were incubated at 37°c for 24 hours. standard antibiotic (ciprofloxacin) disc was used as a positive control and filter paper disc soaked with sterile distilled water was used as a negative control. the antibacterial activity was determined by measuring the diameter of the inhibitory zones with a ruler (clsi, 2012). east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 29 morphological characterization a loop full of the isolates were streaked on each medium and incubated at 30oc for 7 to 10 days. the color of aerial mycelium, reverse color, and nature of the colony was observed and recorded. microscopic characterization the arrangement of spores and sporulating properties of the selected isolates were observed microscopically by using cover slip culture method by placing sterile cover slip at an angle of 45°c in the actinomycete isolation agar medium. a loop full of each isolate was taken separately from 7 d old culture, inoculated at the insertion of cover slip and incubated at 30°c for 7 d. then, the cover slip was removed by using sterile forceps and placed upward on a clean glass slide. finally, the cover slip was observed for the morphology of isolates under the microscope at 100x magnifications (cappuccino and sherman, 2002). gram stain a thin smear of the 7 d old actinomycetes cultures were inoculated into grease free slides. thereafter, they were heat fixed and placed in a staining rack. the slides then flooded with crystal violet for one minute and then rinsed with distilled water gently. gram’s iodine was then gently flooded on the smears and allowed to stand for one minute before gently rinsing with distilled water. this was then decolorized using 95% ethyl alcohol for 20 seconds and immediately rinsed with water to avoid over decolonization. finally safranin was gently flooded on the smears and let to stand for one minute before rinsing with distilled water. the slides were then blot dried using absorbent paper and then viewed using a light-microscope under oil-immersion (100x) (cappuccino and sherman, 2002). physiological characterization temperature on growth the identified isolates were streaked on actinomycetes isolation agar and incubated at 25°c, 30°c, 37°c and 40°cat ph of 7 and after 7 d their growth was observed. the optimum temperature for maximum growth was determined by visual examination of the growth. biochemical characterization urea hydrolysis sterile urea agar slants were inoculated with the isolate, incubated at 30°c for 7 d and inspected for color change (betson., 1994; collee et al., 1996). catalase test the presence of catalase enzyme in some microorganisms causes decomposition of hydrogen peroxide to water and oxygen and this helps them in survival since hydrogen peroxide is lethal to cells. a modified version of the method described by cappuccino and sherman, (2002) was used in which isolates were grown on starch casein agar plates at 30oc for 7 d and thereafter a colony was picked with a sterile stick and placed on a sterile glass slide containing a drop of hydrogen peroxide. production of bubbles was indicative of positive results hence the production of free oxygen (collee et al., 1996). east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 30 starch hydrolysis the isolates were streaked on starch agar plates and incubated at 30°c. after 7 days of incubation, hydrogen hydrolysis was checked by pouring iodine solution on the agar for hydrolysis of starch. production of clear zone around the microbial growth indicates starch hydrolysis (a positive result). starch in the presence of iodine imparts a blue-black color to the medium indicating the absence of starchsplitting enzymes and representing a negative result (benson, 1994; collee et al., 1996). citrate test simmons citrate agar slant were prepared and a single colony of the isolates were streaked on the surface of the slant culture. then the slants were incubated at 30ºc for 7d. after 7d of incubation the citrate utilizing bacteria were produced a blue color in slant surface of the media as a result of alkaline end products. this indicates the tested bacteria were citrate positive (collee et al., 1996) oxidase test a small amount of actinomycete isolates were obtained from 7 day old culture and put on sterile filter paper. then 1-2 drops of tetramethyl phenylenediamine dihydrochloride was added to the culture and the reaction was observed. a positive reaction was indicated by a color change to dark blue or purple and a negative test will result in the absence of color (betson., 1994; collee et al., 1996). statistical analysis the collected data were analyzed using spss version 20.0. inhibition zone measurements obtained in triplicate were compared using a one-way anova followed by duncan's multiple range test to determine the effect of different isolates against different test pathogens. all results statistical results with p < 0.05 were considered to be statistically significant. results isolation of actinomycetes twenty nine (29) isolates of actinomycetes were isolated from 20 different soil samples of which 12(41.38%) from mount tabor, 11(37.93%) from main campus, 4(13.79%) from mount alamura and 2(6.89%) from monopol (table 1). all the 29 isolates grown on actinomycetes isolation agar showed morphology typical of actinomycetes. the colonies were slow growing, aerobic, wrinkled and with aerial and substrate mycelia of variable colors. table 1: actinomycetes isolates from soil samples collected from different sites of hawassa city collection sites no. of soil samples no. of isolates codes mount tabor 5 12 ab1-ab12 main campus 5 11 ab13-ab23 mount alamura 5 4 ab24-ab27 monopol 5 2 ab28-ab29 east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 31 antimicrobial activity screening of the isolated actinomycetes from the 29 isolated actinomycetes, 19 (65.5%) showed antimicrobial activity against at least one of five test bacteria isolates. sixteen (16) actinomycetes isolates showed antimicrobial activity against s. typhi, thirteen (13) showed antimicrobial activity against s. aureus, nine (9) showed antimicrobial activity against k. pneumonia, seven (7) actinomycetes isolates showed antimicrobial activity against s. boydii and two (2) showed activity against e. coli (fig.1). figure 1: number of active actinomycetesthat inhibited tested microorganisms (sb-shigella boydii, ec-escherichia coli, kp-klebsiella pneumonia, st-salmonella typhi, sastaphylococcus aureus) antimicrobial screening total number of isolates which showed positive result in antibacterial activity (at least against one test bacteria) was 19 (65.5%). salmonella typhi was susceptible to all the isolates apart from isolates ab2, ab10 and ab14. on the other hand, e. coli was resilient to most of the isolates apart from isolates ab9 and ab25. shigella boydii was also resistant to most of the isolates apart from isolate ab1, ab2, ab6, ab13, ab19, ab22 and ab25. among the tested isolates ab1, ab4, ab5, ab6, ab9, ab13, ab22, ab25 and ab27 proved to be a broader spectrum antibiotic as they worked good against most of the test organisms. among broader antibiotic spectrum isolates ab13 and ab25 were proven to inhibit four of five test pathogens. isolates ab16 and ab20 showed poor activity. they were only active for salmonella typhi. isolates ab2, ab3, ab7, ab10, ab14, ab19, ab24 and ab28 showed dual inhibition. among active isolates tested against human pathogens, six (6) isolates were active against gram negative bacteria and only east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 32 thirteen (13) isolates were active against both gram positive and gram negative bacteria, and no isolate was found active against only gram positive bacteria (table 2). table 2: sensitivity of selected test microorganisms for actinomycetes isolated from different sampling sites actinomycetes isolates test microorganisms spectrum activity sampling site e.coli k.pneumonia s.boydii s.typhi s.aureus ab1* tabor + + + 3 ab2 tabor + + 2 ab3 tabor + + 2 ab4* tabor + + + 3 ab5* tabor + + + 3 ab6* tabor + + + 3 ab7 tabor + + 2 ab8 tabor 0 ab9* tabor + + + 3 ab10 tabor + + 2 ab11 tabor 0 ab12 m.c 0 ab13* m.c + + + + 4 ab14 m.c + + 2 ab15 m.c 0 ab16 m.c + 1 ab17 m.c 0 ab18 m.c 0 ab19 m.c + + 2 ab20 m.c + 1 ab21 m.c 0 ab22* m.c + + + 3 ab23 m.c 0 ab24 alamura + 1 ab25* alamura + + + + 4 ab26 alamura 0 ab27* alamura + + + 3 ab28 monopol + + 2 ab29 monopol 0 legend: + = active against test organism; = inactive against test organism, *= show broad spectrum activity, m.c=main campus from a total of 29 isolates of actinomycetes tested for antimicrobial activity against human pathogenic bacteria: escherichia coli, klebsiella pneumonia, s. boydii, salmonella typhi and staphylococcus aureus, 19 (65.5%) isolates showed antimicrobial activity against at least one test microorganism. all of the inhibition zones produced by isolates showed significant differences when compared with control ciprofloxacin tested against test organisms (p<0.05). the antimicrobial activity of all the isolates tested against k. pneumonia were statistically significant (p<0.05) from ciprofloxacin (25.16 mm) which was the control drug (table 3). escherichia coli was resistant to all of the isolates except isolates ab9 and ab25. the two isolates that showed antimicrobial activity against e. coli were east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 33 significant as compared with control drug ciprofloxacin (18.33 mm). when compared with control drug ciprofloxacin (18.33 mm), isolate ab25 showed good antimicrobial activity (15.8mm) as opposed to isolate ab9 (9.45mm). the zones of inhibition of active isolates against s. boydii were significant (p<0.05). isolate ab6 exhibited good activity (21.90mm) when compared with control ciprofloxacin (26.25mm) as opposed to the rest which were active against s. boydii. table 3: primary screening of antimicrobial activity (mm) of actinomycetes isolates ‘-’: refers inactive, ‘-ve control ’:filter paper disc soaked with sterile distilled water, ‘+ve’ control: ciprofloxacin salmonella typhi was sensitive to most of the actinomycete isolates (84.2%). the highest zone of inhibition was also shown for isolate ab28 against salmonella typhi (29.11mm). inhibition zones produced by ab4, ab6, ab16 and ab28 against salmonella typhi were 26.63mm, 26.21mm, 26.10mm and 29.11mm, respectively, which were strong active when compared with control ciprofloxacin (30.33mm) but all of them were statistically significant (p<0.05). salmonella typhi showed resistant against isolates ab2, ab10 and ab14. thirteen isolates (68.42%) exhibited antimicrobial activity against staphylococcus aureus which was the highest next to salmonella typhi. the isolate ab28 (18.69 mm) showed the highest inhibitory activity against staphylococcus aureus when compared to others. isolates that showed the isolates test microorganisms gram negative gram positive e.coli k.pneumonia s.boydii s. typhi s.aureus ab1 9.25±0.97 13.75±0.91 11.88±0.41 ab2 15.79±0.82 11.20±0.75 ab3 17.62±0.42 12.50±0.68 ab4 10.88±0.41 26.63±0.33 10.74±0.44 ab5 11.92±1.10 18.55±0.62 13.57±0.72 ab6 21.90±0.40 26.21±0.55 11.04±0.37 ab7 17.95±0.44 13.30±0.69 ab9 9.45±0.50 14.48±0.48 11.24±0.67 ab10 10.51±0.78 11.35±0.44 ab13 12.43±0.60 7.93±0.68 17.30±0.27 12.00±0.50 ab14 10.54±0.77 15.08±0.54 ab16 26.10±0.38 ab19 11.68±0.85 18.99±0.58 ab20 8.32±0.17 ab22 13.58±0.66 8.00±1.00 10.80±0.38 ab24 15.00±1.00 16.86±0.34 ab25 15.80±0.18 10.65±0.75 21.80±0.34 6.57±0.25 ab27 10.25±0.86 20.00±0.00 14.33±0.76 ab28 29.11±0.57 18.69±0.32 +ve control 18.33±0.57 25.16±0.76 26.25±0.66 30.33±0.57 25.00±1.00 -ve control east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 34 second, third and fourth antimicrobial activities against staphylococcus aureus were ab24 (16.86mm), ab14 (15.08mm) and ab27 (14.33mm), respectively. all the active isolates tested against staphylococcus aureus also showed statistically significant result (p<0.05) as shown in table 3. among active isolates tested against pathogens, six (6) isolates were active against gram negative bacteria only, thirteen (13) isolates were active against both gram positive and gram negative bacteria and none of the isolate was found active against gram positive bacteria. among the 19 active isolates from soil, the highest number was from mount tabor (47.37%) followed by main campus (16.58%), mount alamura (15.79%) and monopol site (5.26%). according to the spectrum of 19 active actinomycetes, it was found that most actinomycetes inhibited two tested microorganisms (8 isolates) followed by 7, 2, and 2 isolates that inhibited 3, 4 and 1 tested microorganisms, respectively (table 4). table 4: antimicrobial activity (mm) of selected isolates against methicillin resistant staphylococcus aureus (mrsa) in secondary screening isolates control mrsa ab1 ab4 ab5 ab6 ab9 ab13 ab22 ab25 ab27 cipro 11±0 14±1 8±1 16±1 13±1 24±1 cipro: ciprofloxacin, mrsa: methicillin resistant staphylococcus aureus -: no inhibition zone secondary screening based on primary screening, 9 isolates with wider spectrum activity were further tested against methicillin resistant staphylococcus aureus (mrsa) (clinical isolate) using modified disc diffusion method. secondary screening of 9 isolates selected based on primary screening revealed that 5 isolates exhibited inhibition against clinical isolate of methicillin resistant staphylococcus aureus (mrsa), with inhibition zone size above 8mm to 16mm diameter. isolates ab1, ab13, ab22 and ab27 did not show any antimicrobial activity during secondary screening against mrsa. the antimicrobial activities of isolates were statistically significant (p<0.05) when compared to the standard antibiotics of ciprofloxacin. among those five isolates, 4 of them were from mount tabor site and 1 from mount alamura site. three isolates (ab5, ab9 and ab25) revealed maximum zone of inhibition (i.e. large diameter) against methicillin resistant staphylococcus aureus (mrsa) (clinical isolate). two of them were isolated from mount tabor site and one was from mount alamura (table 4). characterization of selected actinomycete isolates after taking the ph of all soil samples, it was found that almost all soil samples were neutral to alkaline except three samples from monopol site which were acidic (less than ph value of 6). based on secondary screening against methicillin resistant staphylococcus aureus east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 35 (mrsa) (clinical isolate), five (5) active broad spectrum actinomycete isolates namely ab4, ab5, ab6, ab9, and ab25 were used in characterization. morphological characterization macroscopic features of the selected isolates were studied by culturing the isolates on actinomycetes isolation agar (aia), nutrient agar and yeast extract malt agar. the isolates showed different growth patterns on each of the medium. the growth of the actinomycete isolates were highest in actinomycetes isolation agar (aia), moderate growth was observed at yeast extract malt agar, and low growth was seen at nutrient agar comparatively. the nature of colonies was found rough, smooth, chalky, and powdery and it was noted that colonies had different colors ranging from white, whitish, yellow, brown, and pink colonies on actinomycetes isolation agar (aia) plates. some colonies were very hard to pick from agar surface, which is also a characteristic of actinomycetes. the microscopic observations showed that all the isolates were gram positive as they retained the primary color (crystal violet) hence appeared blue and this is a characteristic of actinomycetes (table 5). table 5: the morphological characteristics of the isolates on actinomycetes isolation agar isolates appearance of colonies gram stain ab4 white powdery gram positive ab5 brown rough gram positive ab6 pink gram positive ab9 yellow smooth gram positive ab25 whitish yellow gram positive physiological and biochemical characterization in biochemical tests, all the isolates were able to hydrolyze both starch and urea. citrate was positive for all the isolates, all the isolates showed positive result for catalase test and oxidase was also positive for all the isolates. isolates ab4 was grown at a temperature range of 25-30°c, ab9 on a temperature range of 3037°c while none of the isolates were able to grow at the temperature of 40°c. optimum temperature for most of the isolates was found at 30°c (table 6). table 6: physiological and biochemical characteristics of selected isolates types of test characteristics of isolates ab4 ab5 ab6 ab9 ab25 starch + + + + + citrate + + + + + catalase + + + + + urea + + + + + oxidase + + + + + opt. to 25-30°c 30°c 30°c 30-37°c 30°c opt. to: optimum temperature; +: positive; -: negative east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 36 discussion antibiotic resistance is one of the most pressing public health issues worldwide. presently, antibiotic-resistant organisms are extensively emerging and causing great challenge for a number of infectious diseases and current clinical care. as a result, there has been growing curiosity in searching valuable antibiotics from marine and soil actinomycetes in diversified ecological niches (abo-shadi et al., 2010). actinomycetes are the richest sources of bioactive compounds (suthindhiran and kannabiran, 2009). almost 70% of all recognized antibiotics have been isolated from actinomycetes of which 75% and 60% are used in medicine and agriculture respectively (kumar et al., 2012). isolation of actinomycetes has always been facing difficulties while comparing with other bacteria and fungi (williams and cross, 1971). this may be partly associated with their long incubation period. conversely, actinomycetes isolation ratio has increased by pretreatment of the samples by air desiccation for a week (oskay et al., 2004). in this study, out of total 29 actinomycete isolates, 19 (65.5%) exhibited antimicrobial activity on the test pathogens. primary screening using the disc diffusion methods revealed 65.5% (n=19/29) of the isolates were effective inhibitors against the test pathogens. this finding is higher than the finding (26.7%) of the previous study done by abebeet al. (2013) from soil samples of gondar town, north west ethiopia. however, this result is in line with the report of atsede and fassil (2018) that 60% of actinomycete isolates exhibited antibiotic activity against at least one test pathogen. sawasdee et al. (2011) reported that 80% of the isolates revealed antimicrobial activity against at least one test microorganism and this value was higher than the present findings. khasabuli and kibera (2014) also reported that all the isolates is1-is15 showed positive results against at least one tested pathogen. test bacteria showed varied responses to metabolites of actinomycete i.e., being susceptible to one isolate and tolerant to the other isolate. salmonella typhi was susceptible to most of the isolates other than ab2, ab10 and ab14. this was consistent with the report of khasabuli and kibera (2014). escherichia coli were resistant to all of the isolates except from ab9 and ab25 isolates. shigella boydii was susceptible to metabolites from isolates such as ab1, ab2, ab6, ab13, ab19, ab22 and ab25 while it was resistant to the other metabolites from the rest isolates. the results of this study showed that the inhibition zones were maximum against gram negative bacteria when compared to gram positive bacteria. this finding differs from the previous reports of abebe et al. (2013), gebreselema et al. (2013) and atsede and fassil (2018) who reported higher inhibitory effect in gram positive pathogens than in gram negative. several other studies conducted elsewhere also showed gram positive isolates were more susceptible to the antibiotics produced by actinomycetes than gram negative bacteria (sawasdee et al., 2011; sheik et al., 2017). however, a study done in chennai, india reported higher inhibitory effect on gram negative bacteria than gram positive bacteria (fatima et al., 2017) which is in line with the present study. kamal et al. (2018) also reported highest inhibitory effect in gram negative pathogens than gram positive bacteria. the reason for higher antibacterial activity of east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 37 actinomycetes towards gram negative bacteria in comparison to gram positive bacteria tested might be due to the nature of the cell wall of the gram negative bacteria which is easier to break than those of the gram positive bacteria. however, this hypothesis did not hold good with the findings of some researchers, who observed much higher inhibitory reaction against the gram positive bacteria than the gram negative bacteria (basilio et al., 2003; oskay et al., 2004; sacramento et al., 2004). on secondary screening using the disk diffusion methods against methicillin resistant s. aureus (mrsa) five out of nine actinomycete isolates showed antimicrobial activity with different inhibition zones. based on the study conducted by yucel and yemac (2010), the inhibition zone of actinomycetes isolates against mrsa ranged from 0-15 mm. in this study, however, the inhibition zone of nine isolates against mrsa ranged from 0-16 mm which was considered to be good when compared to yucel and yemac’s results (yucel and yemac, 2010). however, the present result is less when compared to the activity reported by abebe et al. (2013) who found zone of inhibition ranged from 0-20mm. such differences in the results of these studies might be partly associated with the variation in the strains and biotypes of actinomycetes sourced from the different habitats. according to the present result, ciprofloxacin had 24±1 mm inhibition zone against mrsa, which had greater inhibition zone when compared to the isolates tested. the results of the current study reveal that, the type of culture medium and incubation temperature has a substantial effect on the production of antibiotics by the antibiotic producing organisms. the aerial mycelium, substrate mycelium growth and colony color exhibited distinct disparity based on the culture media in which the isolates were cultured. among the three culture media used, the preferred medium in this experiment was actinomycete isolation agar where the maximum numbers of colonies were isolated and this may be due to the inclusion of appropriate amount of nutrient in this media under 30°c. this is in agreement with the results of atsede and fassils (2018) who reported 30°c was optimum temperature for most of the potential actinomycetes isolates. kumar et al. (2012) also reported aia as the best media for the isolation of actinomycetes. all the potential isolates in this study have the ability to hydrolyze starch and urea. oxidase, citrate and catalase tests were also positive for all potential isolates. therefore, after observation of cultural, morphological, physiological and biochemical characteristics it was confirmed that these isolates obtained from soil of hawassa belong to the species of the genus streptomyces. previous studies conducted by kalyani et al. (2012); sudha and hemalatha (2015); midhun and girijasankar (2016); ramendra et al. (2016); sreejetha et al. (2016); sujatha and swethalatha (2016) showed that streptomyces sp. being producers of useful bioactive metabolite have an antibacterial effect with a broad spectrum of activities. another study showed that streptomyces species produced about 7,600 compounds which have antimicrobial properties which are highest among actinomycetes producing antibiotics in the soil (das et al., 2010). conclusion & recommendations antimicrobial resistance is a global problem which demands for novel antimicrobial structure east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 38 against pathogenic microbes. actinomycetes are famous for antibiotic production and continued to be explored in hope of getting novel antibiotics. the isolates from soil of hawassa city might be a promising candidate for discovering novel. actinomycetes isolates recovered from mount tabor samples account largest number of antimicrobial bioactive compounds. it is therefore recommended that molecular analysis methods such as dna reassociation and pcr-based fingerprinting techniques (or a combination of these) may tremendously help to deliver broader insight about the entire genetic diversity of soil actinomycetes community. perhaps, these methods may lead to the improvement in isolating valuable strains of soil actinomycetes obtained in this study. acknowledgements the authors are greatly thankful to hawassa university for providing the necessary facilities to carry out this research work. moreover, the ethiopian health and nutrition research institute (ehnri) and hawassa university referral comprehensive specialized hospital are cordially acknowledged for provision of the test pathogens. references abebe b., feleke m. and berhanu a. 2013. isolation and screening of antibiotic producing actinomycetes from soils. asian. pac. j. trop.dise. 3(5):375-381. abo-shadi m., sidkey m. and al-mutrafy m. 2010. antimicrobial agent producing microbes from some soils rhizosphere. j. am. sci. 6:915-925. atsede m., and fassila. 2018. isolation and screening of antibiotic producing actinomycetes from soil. afr. j. biotechnol. 7: 700-714. basilio a., gonzález i., vicente m.f., gorrochategui j., cabello a., gonzález a. and genilloud o. 2003. patterns of antimicrobial activities from soil actinomycetes isolated under different conditions of ph and salinity. j appl microbiol.95: 814-823. berdy j. 2005. bioactive microbial metabolites: a personal view. j. antibiot. 58:1-26. biniam w. 2008. bioactive compounds from alkaliphilic actinomycetes. m.sc. thesis, department of biology (microbiology), addis ababa university, addis ababa. brown a. e. 2009. benson’s microbiological applications: laboratory manual in general microbiology. new york: mcgraw hill. cappuccino j. g. and sherman n. 2002. microbiology: a laboratory manual. benjamin cummings. chaudhary h.s., soni b., shrivastava a.r. and shrivastava s. 2013.diversity and versatility of actinomycetes and its role in antibiotic production. j. appl. pharm. sci. 3:83-94. clsi 2012. performance standards for antimicrobial susceptibility testing; twentysecond informational supplement. clsi document m 100-s22.clinical and laboratory standards institute, wayne. das s., lyla p.s. and khan s.a. 2008.distribution and generic composition of culturable marine actinomycetes from the sediments of indian continental slope of bay of bengal. chin j oceanol. limnol. 26:77-166. das s., ward l.r. and burke c. 2010.screening of marine streptomyces species for potential use as probiotics in aquaculture. aquaculture 305:32-41. fatima m., salim s., aruna j. and. umamaheswari k. 2017. isolation, molecular characterization and identification of antibiotic producing actinomycetes from soil samples. j. appl. pharma. sci.7: 069-075. gebreselema g., feleke m. and samuel s. 2013.isolation and characterization of potential antibiotic producing actinomycetes from water and sediments of lake tana, ethiopia. asian pac. j. trop. biomed. 3:35-42. hong k., gao a., xie q., gao h., zhuang l. and lin h. 2009. actinomycetes from marine drug discovery isolated from mangrove soils and plants in china. mar drugs.7: 24-44. jensen p.r., williams p.g., oh d.c., zeigler l. and fenical w. 2007.species-specific secondary metabolite production in marine actinomycetes east afr. j. biophys. comput. sci. (2024), vol. 5, issue 1, 25-39 39 of the genus salinispora. appl. environ. microbiol.73:46-52. kalyani a.l.t., ramya s.k.m. and annapurna j. 2012. isolation and characterization of antibiotic-producing actinomycetes from marine soil samples. int. j. curr. pharm. res. 4:109-112. kirby b. 1979. susceptibility test with single, highconcentration antimicrobial disks. antimicrob agents chemother. 3: 418-424. kirst h.a. 2010.the spinosyn family of insecticides: realizing the potential of natural products research. j. antibiotics. 63:101-111. kumar p., john r., veeramuthu d. and savarimuthu i. 2012. antibacterial activity of some actinomycetes from tamil nadu, india. asian pac. j. trop. biomed. 2:936-943. midhun k.d. and girijasankar g. 2016. isolation, screening and characterization of antibioticproducing actinomycetes from kapuluppada plastic waste dumping yard, visakhapatnam. int. j. pharm. pharm. sci. 8:221-229. mogesk. 2009. antimicrobial compound from thermophlic actinomycete isolated from mushroom compost. m.sc. thesis, department of biology (microbiology), addis ababa university, addis ababa. moncheva p. s., tishkov n., dimitrova v., chipeva s.a., chipeva n. and bogatzevska n. 2002. characteristics of soil actinomycetes from antarctica. j. culture collections. 3:3-14. ningthoujam d. s., sanasam s. and nimaich s. 2009. screening of actinomycete isolates from niche habitats in manipur for antibiotic activity. am. j. biochem. biotechnol. 5: 21. oskay m., tamer ü. a. and azeri c. 2004. antibacterial activity of some actinomycetes isolated from farming soils of turkey. afri. j. biotechnol. 3: 441-446. ramendra s.p., charu s., pragati s. and ajay k. 2016. isolation and screening of antimicrobial and extracellular pigment producing actinomycetes from chambal territory of madhya pradesh region, india. asian. j. pharm. clin. res. 9:157-160. ramesh s. and mathivanan n. 2009. screening of marine actinomycetes isolated from the bay of bengal, india for antimicrobial activity and industrial enzymes. world j. microbiol. biotech. 25:3-11. reddy n. g, ramakrishna d.n. and raja g.v. 2011. morphological, physiological and biochemical studies of marine streptomyces rochei (mtcc 10109) showing antagonistic activity against human pathogenic microorganisms. asian j. biol. sci. 4(1):1–14. sacramento d.r, coelhor. r., wigg m.d., linhares l.f.., santos m.g., semêdo l.t. and silva a.r. 2004. antimicrobial and antiviral activities of an actinomycetes (streptomycessp.) isolated from a brazilian tropical forest soil. world j. microbiol. biotechnol. 20: 225-229. sawasdee s., phongpaichit s., rukachaisirikul v. and sukhoom a. 2011. screening for antimicrobial substance producing actinomycetes isolated from soil. burapha university national conference 2011.6-7th july 2011, burapha university, thailand. sreejetha m., divyaveena s. and kokati v.b.. 2016. the bioactive potential of streptomyces variabilis-dv-35 isolated from thottada marine sediments, kannur, kerala. asian j. pharm. clin. res. 9:67-71. sudha s.k. and hemalatha r. 2015. isolation and screening of antibiotic-producing actinomycetes from the garden soil of sathyabama university, chennai. asian j pharm. clin. res. 8:110-114. sujatha p. and swethalatha p. 2016. isolation and screening of novel streptomyces from sediments of bay of bengal near srikakulam coast. int. j. curr. pharm. res. 9:40-44. suthindhiran k. and kannabiran k. 2009. cytotoxic and antimicrobial potential of actinomycete species saccharopolyspora salina vitsdk4 isolated from the bay of bengal coast of india. amer. j. infect. dis. 5: 90-98. williams s.t., and cross t. 1971. actinomycetes, applied microbiology 4 academic press. yucels., and yemac m. 2010. selection of streptomyces isolates from turkish karstic caves against antibiotic resistant microorganisms. pak. j. pharm. sci. 23:1-6. . east afr. j. biophys. comput. sci. (2022), vol. 3, issue. 1, 43-57 *corresponding author: email: twesigyeck@yahoo.com, +256 782 353 775 https://dx.doi.org/10.4314/eajbcs.v3i1.5s assessment of vegetation in murchison falls national park five years after the completion of oil and gas exploration hindrah akisiimire1, william tinzaara2, keneth tumwebaze3 and charles k.twesigye1*, 1department of biological sciences, kyambogo university, p.o. box 1, kyambogo, kampala, uganda 2department of agricultural production, kyambogo university, p.o. box 1, kyambogo, kampala, uganda 3department of environment management, college of agricultural and environmental sciences, makerere university, p.o. box 7062, kampala, uganda keywords: biodiversity hotspot; ecological restoration; plant species diversity; uganda abstract uganda discovered petroleum deposits in commercially viable quantities in 2006. most areas such as murchison falls national park (mfnp) where petroleum has been discovered overlap with wildlife and nature conservation with high biodiversity and sensitive ecosystems. this study sought to study the vegetation frequency index, relative abundance and diversity in former oil pads five years after the completion of oil and gas exploration in mfnp. we counted all observed plant species following a systematic random sampling technique using a (1mx1m) quadrat for herbs, (5mx5m) quadrat for shrubs, and (10mx10m) quadrat for trees. data was collected using a 60m line transect to record the identified plant species. the study used a total of eight quadrats per transect and the total number of transects were 32. a quadrat was placed every after 7m along the line transect in and outside the oil pads. each transect begun from the center (placard) of the oil pad going in directions of center to north, center to south, center to east, and center to west. this was carried out for purposes of replication and the same procedure was carried out for the control area. the same procedure was conducted at a frequency of wet (4 th-30th april 2019) and dry (1st-30th june 2019) seasons. the counted data was later transformed and analyzed using t-statistical tests and chisquare tests in spss version 20 software. the study recorded uniform and non-uniform plant species and the mean vegetation diversity of 1.9±0.06 in oil pads and 1.71±0.12 in control areas. the study identified 31 different plant species, and among these, seven plant species were recorded in oil pads, eight in control areas. the results of vegetation relative abundance and diversity between oil pads and control areas were generally similar. however, the study observed some plant species such as desert date (balanites aegyptiaca) in control areas that were completely absent in oil pads. further studies focusing on edaphic assessments, soil chemical, and biological analysis to better understand the impacts of oil exploration in the protected area are recommended. introduction oil was first discovered in western uganda in the 1870s, but commercially viable oil was only confirmed in 2006 (rwakakamba and lukwago, 2013). approximately 2.5 billion barrels of commercially viable oil of $2 billion worth in annual revenue for twenty years (shepherd, east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article mailto:twesigyeck@yahoo.com https://dx.doi.org/10.4314/eajbcs.v3i1.5s east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 44 2013) was discovered under the ugandan portion of the albertine rift in 2006. this would make uganda the fifth largest oil producer in africa (vokes, 2012). the government of uganda went ahead in the early 2000s and licensed the exploration of oil prospects in the country. the government made agreements with oil companies which include dominion uganda ltd, tullow oil plc, heritage oil and gas ltd and neptune petroleum uganda limited (nema, 2009). these companies discovered oil quantities in the albertine rift and along the boundary of uganda and democratic republic of congo (drc). uganda hosts a number of protected areas including the queen elizabeth national park, rwenzori mountains national park (both are world heritage sites), kibaale, semlikiand murchison falls national parks, plus toro-semliki and kabwoya wildlife reserves (usaid, 2007). seven of the ten national parks and over 20 forest reserves are located in the albertine rift. the albertine rift provides ecosystem services such as tourism, water systems through lakes, rivers and wetlands. it also supports people by providing a source of livelihoods via forests, wetlands, minerals and fertile soils. global economic development and demand for energy have led to an expansion in oil and gas exploration, and oil and gas reserves in many cases overlap with protected areas and biodiversity hot spots (harfoot et al., 2018). for example, the albertine rift is a known hotspot of mammals, birds and plant species in uganda. the wildlife law in uganda allows exploration and extraction of oil under protected areas, provided that the impacts to the environment are minimized and where possible the natural habitat is restored after extraction. initial drilling was promising, and it expanded from the kabwoya wildlife reserve to other sites around lake albert including murchison falls national park (mfnp). uganda, gabon and the democratic republic of the congo are some of the african regions where oil exploration has occurred in protected areas (coghlan, 2014; dowhaniuk et al., 2018). human activities in a national park can lead to habitat loss from an increasing and expanding human population which is the greatest threat to a wide diversity of species (brooks et al., 2002). further causes of habitat loss can be recreation and transportation which may have an array of immediate and long-term impacts on species within wilderness parks (trombulak and frissell, 2000). kityo (2011) also noted that other potential impacts due to increased human presence and traffic would include increased incidents of road kills, soil spills (an oil or fuel spill) on site which would result into an ecological disaster, destroying wildlife grazing rangelands and wildlife. clearing of vegetation along seismic lines and pipelines can fragment habitat and alter predator–prey interactions (borasin et al., 2002). construction of drill pads, new roads and fences results into habitat loss and exacerbates fragmentation (uwa, 2012). additionally, improved access to remote areas can increase poaching and the oil spills can have devastating effects on entire ecosystems (johnson, 2007; rwakakamba et al., 2014). northrup and wittemyer (2013) pointed out energy development impacts on wildlife as pollution, removal of vegetation for roads and oil pads, increased poacher access, altered animal migration and foraging habits. oil and natural gas development poses heavy threats and dangers towards environmental conservation and the health and safety of the earth’s biodiversity (ericson, 2014). increased road east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 45 traffic due to mining can also threaten protected areas due to increased access to biodiverse regions (laurance et al., 2009), causing drastic change to land cover due to large human migration into areas with low human population density (wilkie and carpenter, 1999; wilkie et al., 2000; laurance et al., 2014). from an ecological perspective, development can cause large-scale and novel alterations to ecosystems, resulting in habitat loss and fragmentation (leu et al., 2008; mcdonald et al., 2009) that strongly impact terrestrial wildlife populations and their ecosystems. the most important and large-scale cause of habitat fragmentation is the expansion and intensification of human land use (burgess and sharpe, 1981). habitat fragmentation has three major components, namely loss of the original habitat, reduction in habitat patch size, and increasing isolation of habitat patches, all of which contribute to a decline in biological diversity within the original habitat (wilcox and murphy, 1985). oil extraction has shown to put biodiversity conservation at risk, as exemplified in the niger delta, where oil spills and gas flaring have damaged biodiversity, destroyed mangrove forests, contaminated beaches, coated birds, endangered fish hatcheries, and disrupted food webs (ugochukwu and ertel 2008).human disturbances from oil and gas activities affect wildlife at different levels. it may affect the structure, composition, and distribution of wildlife populations on a landscape level (wassenaar, 2005; vistnes and nellemann, 2008). various studies have indicated that wildlife displacement is a result of disturbance. for example, in the us state of virginia, reclaimed coal mines had fewer salamanders (corrozino, 2009). in the state of montana, elk continued to avoid a drill pad even after drilling was completed (dyke and klein, 1996). the state of california registered lower bird species richness and abundance four years after the restoration of flood control structures (pattern and rotenberry, 1998). wyoming state in the us experienced the displacement of elks for 2 weeks during the seismic surveys (gillin, 1989). land-use changes and degradation of ecosystems by humans are the biggest global threats to biodiversity and ecosystem services (foley et al., 2005; hooper et al., 2012). oil exploration and production has various phases ranging from seismic surveys, exploratory drilling which confirms the existence or absence and quantities of hydrocarbon reservoirs. this is followed by appraisal drilling whose intention is to know if the reservoir is economically viable for development. this is followed by development and production, and the final stage is decommissioning (kasimbazi, 2012). in some cases, this is followed by restoring the site to environmentally sound conditions. it is achieved by implementing measures to motivate site revegetation and constant monitoring of the site after closure. for the case of mfnp, all drill pads and pad access roads north of the nile were restored upon completion of appraisal drilling in early 2014 (fuda, 2018). restoration involved removal of all equipment and murram (a laterite soil used for building roads in east africa) at the site, scarification of subsoil, reinstatement of topsoil and translocation of native grasses from nearby areas to the decommissioned access road and pad footprint (total e&p uganda, 2013). there was no reforestation of native trees or shrubs, which caused in restored sites being more profoundly east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 46 dominated by grasses, in relative to surrounding areas. thus this study sought to assess the status of vegetation of the former oil pads post exploration stage. we were able to achieve that by studying the vegetation composition in former oil pads by comparing it with sites that are presumed to have never gone through anthropogenic disturbances. materials and methods study area murchison falls national park (mfnp) is located in the northwestern region of uganda and the study area is in the northern part of the park which is the main tourism circuit area. the study sites were located in exploration area 1 and they included jobi 4 with a coordinate of 2 o20ˈ09.5 ̎n, 31 o29ˈ52.4 ̎e and jobi east 7 having a coordinate of 2o20ˈ45.4 ̎ n, 31o32ˈ26.8 ̎ e (figure 1). the study area consists mainly of mosaic grassland, dense borassus woodland, open borassus woodland; open woodland, wooded grassland and bush/shrub. the park’s topography is rolling, reaching a maximum elevation of 1,291 m at rabongo hill in the south east of the park, and the lowest elevation of 619 m at lake albert on the rift valley floor in the west. the park is hot with mean minimum temperature of 22°c and maxima of 29°c all year round. the eastern part of the park is wetter than the western part; chobe to the east receives around 1,500 mm whilst paraa receives about 1,100 mm per year. murchison falls national park has two rainy seasons, from mid-march to mid-june, and from august to november (uwa 2001). the two exploration sites were drilled and restored by replanting of vegetation at different time periods (table 1). control areas were outside the selected oil pads within the same location. restoration involved removal of all equipment and murram (a laterite soil used for building roads in east africa) at the site, scarification of subsoil, reinstatement of topsoil and translocation of native grasses from nearby areas to the decommissioned access road and pad footprint (total & uganda, 2013). there was no replanting of native trees or shrubs, which caused in restored sites being more heavily dominated by grasses, in relative to surrounding areas table 1: time period of exploration and restoration of the study sites exploration site drilled restoration completed by jobi 4 marchapril 2013 june 2013 jobi east 7 julyaugust 2013 may 2014. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 47 figure 1: location of study sites in murchison falls national park in northwest uganda research design the study used quantitative research designs which involved purposive sampling to select the exploration sites and control areas. this was on basis of easy accessibility, the cost involved in travelling, time available, and sites must be under the mandate of uganda wildlife authority. the oil pad sites under the study were selected based on the fact that they must be somewhat a habitat to the mammals in the park. the control area sites were selected based on the assumption that they had the same environmental conditions as the oil pads (jobi 4 and jobi east 7) and had never gone through any human disturbance. the control areas were located 120m away from the oil pad sites. plant counts were replicated for both wet (april 2019) and dry (june 2019) seasons in and outside the oil pads. the study conducted replicated counts along transect lines as one of the sampling principles to ensure that difference in encounter rate (number of objects detected per unit survey effort) can be sufficiently estimated. all transect lines were replicated following similar randomization scheme to give all locations in the study area a known, non‐zero probability of being covered by a transect (figure 2). the east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 48 study used a dichotomous key to identify the plants during the study. identification of the plants was made at the sites without carrying samples to herbarium because it would be tedious. moreover, the research permit issued to us to conduct research in a protected area does not permit carrying plant species outside the park. one of the research assistants involved during data collection was a qualified botanist experienced in plant identification, which made plant identification easy. figure 2:(a) is the 1x1m quadrat used to count plants along a transect, (b) is the placard bearing the oil pad name, time of drilling and restoration, (c) is the borehole that once supplied water to the oil pad camp. data collection plant species counts were conducted in and outside the former oil pad sites using observation and recording method. a systematic random sampling technique (greig-smith, 1983) was followed by using a 1 x 1m quadrat for herbs, 5 x 5m quadrat for shrubs, and (10x10m) quadrat for trees. data was collected following a 60m line transect to record the identified plant species. a quadrat was placed every after 7m along the line transect in and outside the oil pads. in total 8 quadrats x 4 line transects were followed for the sites under the study. each transect begun from the center (placard) of the oil pad going in directions of center to north, center to south, center to east, and center to west. this was carried out for the purposes of replication in order to get the true representation of each site and the same east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 49 procedure was carried out for the control area. the same procedure was conducted at a frequency of wet (4th-30th april 2019) and dry (1st-30th june 2019) seasons. it should be noted that the study intentionally measured vegetation frequency index, vegetation relative abundance and vegetation diversity but did not put in to account the relative cover of the observed plant species due to the limited time and resources that were available for the study. the study was primarily concerned with the uniformity and composition of the plant communities as a whole not the nature of plants and coverage across the sites under the study. data analysis vegetation frequency index the vegetation frequency index was determined using equation 1. the obtained frequency indices were analyzed using raunkier’s law of frequency (1962), which is often used to study the homogeneity or uniformity of plant species in an area. 𝐹𝐼 = { 𝑁𝑜. 𝑜𝑓 𝑢𝑛𝑖𝑡𝑠 𝑖𝑛 𝑤ℎ𝑖𝑐ℎ 𝑡ℎ𝑒 𝑠𝑝𝑒𝑐𝑖𝑒𝑠 𝑜𝑐𝑐𝑢𝑟𝑒𝑑 𝑇𝑜𝑡𝑎𝑙 𝑛𝑜. 𝑜𝑓 𝑢𝑛𝑖𝑡𝑠 𝑠𝑡𝑢𝑑𝑖𝑒𝑑 } 𝑥 100 … … (1) this law of frequency assumes bimodality occurrences to describe vegetation abundance per unit area, which assumes that species are, either present or absent. in raunkiaer’s law, species are categorized in levels/classes based on frequency as: level a (0-20%); b (21-40%); c (41-60%;) d (61-80%); and e (80-100%). the normal frequency ratio is valuable in several kinds of studies in testing the homogeneity of the vegetation in a given area. frequency levels are interpreted as a>b<c>d<e; in general, the higher class e has greater homogeneity/uniformity of the vegetation. the most essential point being that class e should be larger than class d with greater number of species in class e than in d. class a means the plant species under study are very scarce, b means occasional presence, c means infrequent presence, d means frequent presence and e means abundant or very numerous presences of the plant species under the study. vegetation relative abundance the vegetation relative abundance (ra) was determined by employing equation 2, where a refers to the observed individual plant species. 𝑅𝐴 = { 𝑇𝑜𝑡𝑎𝑙 𝑛𝑜. 𝑜𝑓 𝑠𝑝𝑒𝑐𝑖𝑒𝑠 𝐴 𝑇𝑜𝑡𝑎𝑙 𝑛𝑜. 𝑜𝑓 𝑖𝑛𝑑𝑖𝑣𝑖𝑑𝑢𝑎𝑙 𝑜𝑓 𝑎𝑙𝑙 𝑠 ㅳ 搠𝑐𝑖𝑒𝑠 𝑟𝑒𝑐𝑜𝑟𝑑𝑒𝑑 𝑥 100} (2) however, the study compiled mean vegetation abundance of each plant species observed to compare the mean values using t statistical tests. mean vegetation relative abundance (𝜇) was computed by summing up the total number of each plant species (x) observed divided by the total number of quadrats used in the study (equation 3). 𝜇 = 𝑆𝑢𝑚 𝑜𝑓 𝑝𝑙𝑎𝑛𝑡 𝑠𝑝𝑒𝑐𝑖𝑒𝑠 𝑥 𝑇𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑞𝑢𝑎𝑑𝑟𝑎𝑡𝑠 … … … … … … … … . … . . … … (3) all data sorting and computing was conducted using microsoft excel sheets before being transferred to spss software for further tstatistical tests. vegetation diversity vegetation diversity was computed using shannon weiner diversity index (h) that was determined by equation (4). the corresponding east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 50 h max values and equitability values were calculated as well as to help make scientific conclusions of the collected data. calculations were determined using microsoft word excel 2010 before exporting it to spss version 20 for t statistical analysis. vegetation relative abundance and diversity between oil pads and control areas were analyzed using t statistical tests in spss version 20 at p=0.05 significance level. 𝐻 = ∑ p𝒾 ln p𝒾 … … … … … … … … . … … … … . … … … … … … … (4) s i=1 in the shannon index, p is the proportion (n/n); of individuals of one particular species present (n) divided by the total number of individuals present (n), ln is the natural logarism, σ is the sum of the calculations, and s is the number of species. h max values are determined when each group has the same frequency referred to as maximum diversity possible [log(x)]. shannon equitability value or evenness (e) was also determined using equation (5). 𝐸 = 𝐻 𝐻𝑚𝑎𝑥 … … … … … … … … … … … … … … … … … … … … … . (5) where h= shannon-weiner diversity index, hmax = ln(s) and s = total number of species in the sample. results vegetation frequency index per transect the frequency index analysis from the study shows that some plant species are more uniform than others (table 2). the plant species that were observed to be uniform in both oil pads and control areas include thatching grass (hyparrhenia hirta), cat's tail drop seed (sporobolus pyramidalis), nut grass (cyperus rotundus) and wandering jew (commelina benghalensis). plant species which are more uniform in oil pads than control areas include garden signal grass (urochloa panicoides), hippo grass (vossia cuspidate), creeping woodsorrel (oxalis corniculata), star grass (cynodon dactylon), goats weed (ageratum conyzoides), devil horsewhip (achyranthes aspera), pickerel weed (pontederia cantata), tick berry (lantana camara), wait a bit thorn (acacia mellifera), white thorn acacia tree (vachellia constricta), and candle bush (senna alata). however, some plant species were recorded to be less uniform in oil pads than control areas and they include feathered chloris (chloris virgate), bur bristled grass (setaria verticillata), desert date (balanites aegyptiaca), hoket horn (arisonia abyssinica), garden pink-sorrel (oxalis latifolia), borassus palm tree (palmyra palm), edible canna (canna eduls), guatemala (tripsacum laxum), sticking weed (acacia okidetalia), treedax daisy (tridax procumbens), and whistling acacia (acacia hoki). other recorded plant species in the study had similar uniformity in oil pads and control areas and they include finger grass (digitaria eriantha), fibrous drop seed (sporobolus stafianus), nandi grass (cetera ancient), wild canny lilly flower (canna indical), and baboon apple (annona glabra). east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 51 table 2: frequency index, frequency classes, and vegetation relative abundance of the observed plant species per transect in oil pads and control areas. observed plant species scientific name op-fi fc ca-fi fc op-vra ca-vra sig. value thatching grass hyparrhenia hirta 100 e 87.5 e 103.8±30.6 169.6±47.8 * cat's tail drop seed sporobolus pyramidalis 100 e 87.5 e 95.8±20.1 148.1±41.8 * nut grass cyperus rotundus 100 e 100 e 42.3±9.8 95.5±20.0 * wandering jew commelina benghalensis 100 e 100 e 48.6±10.2 58±8.5 * feathered chloris chloris virgata 12.5 a 50 c 9.8±4.9 57.5±28.1 * bur bristled grass setaria verticillata 0 a 12.5 a 0±0 0.75±0.74 *** desert date balanites aegyptiaca 0 a 37.5 b 0±0 9.8±8.9 *** hoket horn arisonia abyssinica 0 a 12.5 a 0±0 2.8±2.7 ** candle bush senna alata 12.5 a 0 a 4.1±4.1 0±0 *** garden signal grass urochloa panicoides 50 c 0 a 1.4±1.4 0±0 ** hippo grass vossia cuspidata 50 c 0 a 7.8±3.1 0±0 *** creeping wood-sorrel oxalis corniculata 50 c 37.5 b 18.6±11.6 14.6±8.0 ns finger grass digitaria eriantha 50 c 50 c 17.4±8.9 9.8±4.0 ns garden pink-sorrel oxalis latifolia 50 c 75 d 15.3±8.4 9.8±4.5 ns star grass cynodon dactylon 87.5 e 75 d 14.5±5.5 13.4±4.2 ns fibrous drop seed sporobolus stafianus 25 b 37.5 b 11.1±8.9 14.1±10.4 ns whitethorn acacia tree vachellia constricta 37.5 b 12.5 a 0.9±0.4 0.9±0.9 ns baboon apple annona glabra 25 b 12.5 a 0.9±0.6 10.6±10.6 ns borassus palm tree palmyra palm 12.5 a 50 c 0.3±0.2 2.6±1.5 ns goats weed ageratum conyzoides 62.5 d 25 b 8±3.7 0.9±0.7 ns nandi grass cetera ancient 12.5 a 12.5 a 0.6±0.6 1.5±1.5 ns wild canny lilly flower canna indical 50 c 50 c 4.6±2.1 5.5±2.2 ns devil horsewhip achyranthes aspera 12.5 a 0 a 0.3±0.2 0±0 ns edible canna canna eduls 0 a 12.5 a 0±0 0.4±0.4 ns guatemala tripsacum laxum 0 a 12.5 a 0±0 0.3±0.2 ns pickerel weed pontederia cantata 12.5 a 0 a 2.8±2.7 0±0 ns sticking weed acacia okidetalia 0 a 12.5 a 0±0 0.1±0.1 ns tick berry lantana camara 12.5 a 0 a 2.9±2.9 0±0 ns treedax daisy tridax procumbens 0 a 12.5 a 0±0 2±1.9 ns wait a bit thorn acacia mellifera 37.5 b 0 a 0.8±0.4 0±0 ns whistling acacia acacia hoki 0 a 25 b 0±0 3±2.0 ns op = oil pads, ca = control areas, fi = vegetation frequency index / percentage frequency, fc = raunkiaer’s frequency classes, a = (0-20%), b = (21-40%), c = (41-60%), d = (61-80%), e = (81-100%), raunkiaer’s formula a>b>c<d<e, op-vra = oil pad vegetation relative abundance, ca-vra = control area vegetation relative abundance, sig.value = significant value, ns= non significant difference, *(p<0.05), **(p<0.01), ***(p<0.001), total number of quadrats per transect= 8, total number of transects in oil pads = 16, total number of transects in control areas = 16 east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 52 vegetation relative abundance per transect the vegetation relative abundance in oil pads has no significant difference from the vegetation relative abundance in control areas (t= -1.946, d.f=30, p=0.061). however, the results show that there were some plant species that were significantly more abundant in control areas than in the oil pads (table 2) which include thatching grass (hyparrhenia hirta), cat's tail drop seed (sporobolus pyramidalis), nut grass (cyperus rotundus), wandering jew (commelina benghalensis), feathered chloris (chloris virgate), bur bristled grass (setaria verticillata), desert date (balanites aegyptiaca), and hoket horn (arisonia abyssinica). on the other hand, some recorded plant species were more significantly abundant in oil pads than control areas and they include candle bush (senna alata), garden signal grass (urochloa panicoides), and hippo grass (vossia cuspidata). table 3: plant species recorded per transect in oil pads and control areas species common name scientific name type of plant oil pads control areas baboon apple annonaglabra shrub + + borassus palm tree palmyra palm tree + + bur bristled grass seteriaverticullata grass + candle bush sennaalata tree + cat's tail drop seed sporoboluspyramidalis grass + + creeping wood-sorrel oxalis corniculata grass + + desert date balanites aegyptiaca shrub + devil horsewhip achyranthesaspera shrub + edible canna canna eduls shrub + feathered chloris chlorisvirgata grass + + fibrous drop seed sporobolusstafianus grass + + finger grass digitariaeriantha grass + + garden pink-sorrel oxalis latifolia grass + + garden signal grass urochbapanicoides grass + goatsweed ageratum conyzoides grass + + guntamala tribsacumlaxom grass + hippo grass vossiacuspidata) grass + hokes horn harrisoniaabyssinica grass + nandi grass cetera ancient grass + + nut grass cyperusrotundus grass + + pickerel weed pontederia cantata grass + star grass cynodondactylon grass + + sticking weed acacia okidetalia grass + thatching grass hyparrheniahirta grass + + tick berry lantana camara grass + treedax daisy tridaxprocumbens grass + wait a bit thorn acacia mellifera shrub + wandering jew commelinabenghalensis grass + + whitethorn acacia tree vachelliaconstricta tree + + whistling acacia acacia hoki tree + wild canna lilly flower canna indical shrub + + total number of plant species present 23 24 + = plant species present, = plant species absent, op = oil pads, ca = control areas, total number of quadrats per transect= 8, total number of transects in oil pads = 16, total number of transects in control areas = 16 east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 53 the study also recorded a non-significant difference in the vegetation relative abundance of some plant species between oil pads and control areas which include creeping woodsorrel (oxalis corniculata), finger grass (digitaria eriantha), garden pink-sorrel (oxalis latifolia), star grass (cynodon dactylon), fibrous drop seed (sporobolus stafianus), whitethorn acacia tree (vachellia constricta), baboon apple (annona glabra), borassus palm tree (palmyra palm), goats weed (ageratum conyzoides), nandi grass (cetera ancient), wild canny lilly flower (canna indical), devil horsewhip (achyranthes aspera), edible canna (canna eduls), guatemala (tripsacum laxum), pickerel weed (pontederia cantata), sticking weed (acacia okidetalia), tick berry (lantana camara), treedax daisy (tridax procumbens), wait a bit thorn (acacia mellifera), and whistling acacia (acacia hoki). observed plant species per transect a total of 16 various grass plant species, 4 shrub plant species and 3 tree species were recorded in oil pads whilst a total number of 17 grasses, 4 shrubs, and 3 trees were recorded in control areas. some of the observed plant species were recorded in both oil pads and control areas, while others were in either of the two sites (table 3). however, the total number of plant species recorded in oil pads were not significantly different from the ones recorded in control areas (2= 8.29, d.f=1, p > 0.05). vegetation diversity per transect the results of shannon weiner vegetation index per transect at both oil pads and control areas are presented in table 4. the results show a relatively higher mean vegetation diversity per transect at oil pads (1.9±0.058) compared to at control areas (1.71±0.120). the study results show a non-significant difference in the vegetation diversity between the former oil pads and control areas (t= 2.114, d.f =7, p=0.072). this indicates that there are no habitat variations post oil and gas exploration. the results indicate a non-significant difference between the vegetation species equitability between oil pads and control areas (t = 2.118, d.f=7, p =0.072). the mean equitability of vegetation per transect in oil pads and control areas is 0.80±0.014 and 0.75±0.029, respectively table 4: vegetation diversity at oil pads and control areas opt h value h max e value cat h value h max e value jobi4 et 2.05 2.48 0.83 ca1 et 1.83 2.20 0.83 jobi4 st 2.16 2.56 0.84 ca1 st 2.47 2.71 0.91 jobi4 wt 1.89 2.40 0.79 ca1 wt 1.42 1.95 0.73 jobi4 nt 1.78 2.20 0.81 ca1 nt 1.38 2.08 0.66 je7 st 1.61 2.20 0.73 ca2 st 1.63 2.30 0.71 je7 wt 1.93 2.40 0.81 ca2 wt 1.63 2.20 0.74 je7 nt 1.91 2.48 0.77 ca2 nt 1.60 2.40 0.67 je7 et 1.86 2.20 0.85 ca2 et 1.72 2.20 0.78 opt=oil pad transect, cat=control area transect, je7 = jobi east 7, h valueshannon weiner vegetation index, h max= maximum species’, e value= species’ equitability. et=east transect, st= south transect, wt= west transect, nt= north transect, ca1= control area 1, ca2= control area 2,total number of quadrats per transect= 8, total number of transects in oil pads = 16, total number of transects in control areas = 16 east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 54 discussion frequency index (fi) of vegetation results from the vegetation frequency index were analyzed by raunkiaer's law of frequency (1962) recorded the uniformity or nonuniformity of plant species in the study area. uniform vegetation signified stable community whilst non-uniformity may suggest a disturbed vegetation community. the study recorded a number of plant species which were more uniform in control areas than in oil pads. this may suggest that these plant species are more abundant in control areas than oil pads. however, it should be noted that distribution of frequencies "depends on the number of quadrats, the size of the quadrats, and on the index of diversity of the population." unless all of these factors are considered, the distribution of frequencies in classes is not meaningful (williams, 1950). another challenge with this methodology of vegetation assessment is that the dissemination of species in the frequency classes differs with the size of sample. the results are highly influenced by the composition of the total population in terms of numbers of individuals per species. vegetation relative abundance the study recorded a non-significant difference in the vegetation relative abundance between oil pads and control areas. the findings are not in line with lee et al. (2013) who suggested that species richness and total vegetation cover (fiori and zalba, 2003) may decrease in response to road construction and natural resource extraction. the results reveal that the plant communities have been able to recover from the human disturbances caused by oil exploration. this is not in line with the report by forbes et al. (2001), which suggested that there is a general slow recovery of plant communities from human disturbances, and other physical impacts of development for decades or centuries. some of the recorded plant species were more abundant in control areas than former oil pads. the findings are similar to those of simmers and galatowitsch (2010) which suggest that, in semi-arid environments, habitats heavily disturbed by anthropogenic activities often have lower species richness compared with undisturbed areas. however, the timeline for recovery may vary by taxa and level of disturbance (nichols and nichols, 2003; walker and moral 2003). this could be an explanation why some plant species were abundant in oil pads than control areas. encounters of more abundant plant species in former oil pads is contrary to the findings by prinsloo et al. (2011) which suggested that oil and gas development leads to decrease in vegetation cover. the study recorded some plant species which were more abundant in former oil pads than control areas and this is similar to larson et al. (2001), whose findings indicate that reclaimed sites tend to have a higher abundance of species. this is because reclamation introduces new plants and offers moist and humid soil‐water which are better conditions than reference sites. this causes the reclaimed oil pads to have greater richness and higher abundance of the introduced plants. vegetation diversity the study recorded a non-significant difference in the vegetation diversity between oil pads and control areas. this is similar to lupardus et al. east afr. j. biophys. comput. sci. (2022), vol. 3, no. 1, 43-57 55 (2020) whose findings did not detect significant differences in species richness of recovering grasslands between reference and reclaimed well pads. however, the current study findings of no significant difference were contrary to findings by edwards et al. (2014) which noted that mining infrastructure fragments and degrades natural habitat through the creation of roads. another study conducted by cui et al. (2009) and janz et al. (2019) found out that disturbances can have immediate and persistent or long‐lasting effects with slow recovery times on vegetation. the results are also contrary to unep (1997), epstein and selber (2002), kumpula et al. (2011), ogp/ipieca (2011) and kamara et al. (2019) whose findings indicated that natural resource extraction of oil and gas exploration had well documented impacts on wildlife as well as vegetation. the fact that the vegetation diversity in oil pads is similar to that in control areas is a good indicator that the habitats for mammals has been fully restored. conclusions in general, the results of the current study revealed that the vegetation at the former oil pads has been fully restored. the oil exploration has not generally changed vegetation in the protected area. the oil pads are recovering at a steady rate given there is no observable difference of the vegetation relative abundance and diversity between oil pads and control areas. based on these findings, oil companies should always do baseline studies before any development activities are carried out. the findings can serve as a benchmark for restoration once oil activities are complete. moreover, further research studies are recommended in the former oil pads about edaphic assessments, soil chemical, and biological properties analysis. the studies would provide information to better understand if exploration altered the quality of soil in any way and also provide better guidance for further development phases of oil and gas in the park. acknowledgements the authors are grateful to uganda wildlife authority (uwa) for giving us access to murchison falls national park to conduct this study. we also extend our appreciation to the uwa staff in the park who made our work easier by giving us all the necessary assistance needed. we wish to acknowledge the great support of dr. sylivia nalubwama and mr. kitimbo herbert for the valuable guidance, technical support, generosity and direct collaboration during this study. author contributions ha, ckt and wt conceived and designed the study; ha and kt conducted the research; ha and wt analyzed the data; ha and ckt wrote the paper. all the authors (ha, ckt, wt and kt) reviewed and approved the paper for submission. references borasin s., foster s., jobarteh k., link n., miranda j., pomeranse e. and somaia p. 2002. oil: a life cycle analysis of its health and environmental impacts. https://www.fraw.org.uk/library/toxics/epstein_2006 .pdf. brooks t.m., mittermeier r.a., mittermeier c.g., da fonseca g.a., rylands a.b., konstant w.r. and hilton‐taylor c. 2002. habitat loss and extinction in the hotspots of biodiversity. conserv. biol. 16(4): 909-923. burgess r.l. and sharpe d.m. 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(2024), vol. 5, issue. 2, 1-12 mixed effects analysis of height growth in ethiopian children aged 1-12 years: a cohort study dereje danbe debeko*1 and ayele taye goshu2 1 department of statistics, hawassa university, p.o. box 05, hawassa, ethiopia 2 department of statistics, cotebe teaching university, addis ababa, ethiopia keywords: height growth; mixed effects models; children; ethiopia abstract modelling physical growth is a key component to examine and identify defining characteristics in the growth process. the goal of this study was to model and capture known features of height growth in ethiopian children aged 1–12 years. height measurements of 1760 children followed from 1 to 12 years at young lives ethiopia, a younger cohort, used in the study. the mixed effects method was used to estimate the rate of change within and between subjects over time and to identify defining covariates. adult height and rate of change over time were individual-specific resulting individual-level growth differences. there was a negative relationship between individual-specific adult height and rate of change over time. the decelerated rate of change was observed from childhood to the onset of puberty in both sexes. boys were taller than girls between the ages of 3 and 7 years. mother’s educational status, access to quality drinking water, age, and sex had a significant effect on height growth. children who had a decelerated rate of growth change during the childhood period become taller later in life. adult height could be determined by an individual-specific rate of change over time. introduction growth is a continuous and dynamic process influenced by different unknown factors. modelling this dynamic process to understand, estimate, and capture the defining characteristics such as initial level, rates of change, periods of acceleration and deceleration when the process enters and leaves different developmental phases (grimm et al., 2011; howa et al., 2016). a common practice of child growth is to measure the increase in body mass, to control and modify the external conditions that affect growth gain (oliveira et al., 2000; gómez et al., 2008; aggrey, 2009). there have been different modeling approaches applied to the growth measurement to identify defining characteristics in growth process. an example is the construction of the curve-fitting models that relate age with height and estimate age at which an individual attain maximum growing by associating features in various growth phases (laird, 1965; grossman et al., 1985; grossman and koops, 1988; galeanovasco et al., 2014). studying growth in one phase may have an important influence or east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx *corresponding author: email: dalbrayii@gmail.com +251913927596 https://dx.doi.org/10.4314/eajbcs.v5i2.1s research article 2 association with subsequent phases since individual growth is monitored as a sentinel indicator of overall well-being (tanner, 1981; gold stein et al., 2002; richard et al., 2014). many growth modelling approaches are used to obtain descriptions of change in growth processes accounting individual specific effects observed over time, average change, betweenindividual differences in change and to identify determinants factors (grimm et al., 2011). however, modelling growth trajectory is difficult process due to the model parameters that could not be possible to elaborate from biological perspectives (aggrey, 2002; aggrey, 2009; galeano-vasco et al., 2014). many scholars have been used cross-sectional data to model features in growth process. despite of cost effectiveness and easy access to data, crosssectional centiles for example, only offer a cross-sectional coverage, and hence the growth path of an individual monitored longitudinally in time is unknown since these types of modelling do not describe the dynamic aspect of growth process over time (grajeda et al., 2016). the mixed effects modeling approaches are among the commonly used methods to capture growth process. this modelling approach is capable of incorporating subject specific rate of change over time and difference across the subjects in the linear predictor expression form (bates et al., 2015). mixed effects models have been applied to the longitudinal data in different settings (devidian and giltinan, 1995; pan and goldstein, 1998; grimm et al., 2011; richard et al., 2014; chirwaet al., 2014). in this approach, mixed effects refer to the population mean of the parameter and random effects that indicate the differences between the mean value of the parameter and the adjusted value for each east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 1-12 subject (littell et al., 2000; wang and zuidhof, 2004). the mixed effects methods quantify variability between and within individuals letting a flexible covariance structure (pinheiro and bates, 1995; aggrey, 2009) to accommodate time dependent and time independent covariates within individual residual terms (pan and goldstein, 1998). many studies have been used the mixed effects models in linear and nonlinear approaches (pan and goldstein, 1998; craig and schinckel, 2001; schinckel et al., 2005; aggrey, 2009; grimm et al., 2011). however, both modelling approaches have not been applied to the longitudinally collected data from low income countries’ settings. thus, the main objective of the current study was to model height growth in ethiopian children aged 1-12 years and to identify determinant factors using mixed effects modelling approaches in linear and nonlinear forms. materials and methods the study design and source of data data on growth measurement gathered over time by young lives ethiopia, a younger cohort, was used in this study. young lives is an international collaborative research project supported and coordinated by a team based at oxford university, uk. the cohort has been studying the lives of children in ethiopia aiming to reduce childhood poverty. this project built up lives of 3,000 children living in 20 sites across addis ababa (the capital) and four other regions (amhara, oromia, former southern nations nationalities and peoples (snnps), and tigrai). the young lives ethiopia cohorts have been aimed to follow children in two age groups: a younger cohort following of 2,000 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 1-12 3 children who were 0.5 to 1.5 years old and an older cohort following 1,000 children aged 7.5 to 8.4 years at the baseline (first round) in 2002. the rest three rounds of surveys were carried out in 2006, 2009, and 2013, respectively, for both cohorts. details of the cohort studies have been referred via the official website of the project (www.younglivesethiopia.org). based on the inclusion criteria, a total of 1760 children were included in the study. height growth measurements observed from each subject in four survey rounds were used as outcome variable (see figure 1). age and other socioeconomic, demographic and health related covariates were included in the study. statistical methods two modeling approaches were used in the data analysis as described in the next section. the linear mixed effects modeling approach was used to identify determinant factors associated with height growth difference between and within subjects. the nonlinear mixed effects modeling approach was used to capture growth trajectories and to estimate relationship between rate of change over time and maximum (adult) height. linear mixed effects models linear mixed models (lmms) may be expressed in different but equivalent forms. it is common to express such a model in hierarchical form, or just as a mixed model, including additional random-effect terms and associating variance and covariance components (john and sanford, 2015). when the levels that we observed represent a random sample from the set of all possible values, the random effects can be incorporated in the model (bates, 2010). this approach decomposes the outcome of an observations as fixed effect (population mean) and random effect (subject specific change over time), and it account for the correlation structure of variations among subjects. figure 1: individual height growth measurements plotted on measurement time by sex (male: left and females right). east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 1-12 4 model description lmms used in this study have only two-levels, across and within individual variations. for ijy is height measurements of ith subject taken on jth measurement occasion, where j = 4; i = 1,2,…,n. the extended form of linear model with random components is described as follows: ijqijiqijipijpijij zbzbxxy   ...... 1111 the matrix form of this model is equivalent and considerably simpler to write as: ,0 ijiiijij bzxy   where ijy is the × 1 vector of response observations in the thi subject at thj measurement occasion, ijx is the pni  model matrix of fixed-effect regressors,  is the 1p vector of fixed-effect coefficients which is invariant across groups, iz is the qni  matrix of regressors for the random effects of observations in subject i , ib is the q × 1 vector of random effects for group i , potentially different in different groups and ij is the × 1 vector of errors for thj measurement in thi subject. model assumptions the linear mixed effects analysis was performed with some assumptions: random effects are different across the subject and normally distributed with mean zero and variance covariance structure, covariates are uncorrelated with each other (no multicollinearity), time variant covariates are a subset of the time invariant covariates, error terms are assumed to have a multivariate normal distribution and within subject measurement errors are auto correlated. under certain conditions, physical growth does not follow linear pattern over time. modeling growth spurts using linear form of models could lead us into wrong conclusion and may have weak prediction power. thus, the nonlinear models are alternative ways of modeling growth spurts. this modelling approach uses mixed or fixed effects form based on the objectives of underlying study. non-linear mixed effects models nonlinear mixed effects models refer to the population mean of the parameter and random effects that indicates the differences between the mean value of the parameter and the adjusted value for each individual growth over time (wang and zuidhof, 2004).the nonlinear mixed effects growth curve models used in this study are logistic and gompertz which are most commonly used growth curve models due to their mathematical tractability with biologically meaningful parameters. logistic model (nelder, 1961) ij ijii i ij tbb b y        ))(exp()(1 3322 11 5 gompertz model (winsor, 1932) ijijiiiij tbbby   ))(exp()exp(()( 332211 where, ijy is height of thi subject at thj measurement occasion, ijt is age of thi subject at thj measurement time, 1 is asymptotic or maximum height (adult height), 2 is scaling parameter and 3 is growth rate (between subjects); ib1 is random effects for 1 , ib2 is random effects for i2 , ib3 is random effect for i3 and ij is error term. kik nb ,0(~ ), ),0(~ 2 nij for 3,2,1k ,               333231 232221 131211 bbb bbb bbb k since our sample data is repeated measurements taken on the same subject, the expression for the within-subject variance-covariance matrix can be formed in the following way: inii ir  2 , ini = an identity matrix ( ii nn  ), i = correlation structures and 2 = residual variance of the model. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 1-12 methods of parameter estimation maximum likelihood estimation method was implemented to estimate underlying model parameters using r-package “lme4” and “nlme”. statistical test was done at 5% level of significance. further details of mixed effects model parameter estimation has been described by lindstrom and bates (1990), lindstrom and bates (1995), davidian and giltinan (1995) and, sedigheh and debasis (2012). model adequacy checking the model assumptions were checked using residual plots versus fitted values, qq and p-p plots. the goodness of fit was tested based on the bayesian information criteria (bic) and akaikie information criteria (aic). however, some scholars argue that several measures of model fit, even the likelihood ratio chi-square, that often appear to reflect relatively poor fit – when a model fits data very closely – that is, if residual variances are quite small (browne et al., 2002). results descriptive statistics descriptive statistics of height measurements taken on each survey visit presented below in table 1. more height growth variation was observed in girls than in boys after period i. growth variation became higher in the fourth period for both sexes east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 1-12 6 table 1: summary statistics of height in each measurement periods by sex. measurement period in years female male n min max mean std. d n min max mean std. d period i (age 1) 841 56.00 89.50 70.425 5.498 947 55.30 89.50 71.45 5.227 period ii (age 5) 843 86.50 124.00 103.563 5.512 947 80.90 124.90 103.95 5.291 period iii (age 8) 843 99.10 157.00 120.628 6.469 947 102.0 146.00 120.66 6.129 period iv (age 12) 843 118.2 178.00 142.205 7.880 947 120.0 161.50 139.80 6.628 figure 2: smooth line curve of height growth over measurement time by sex boys and girls had almost the same height between 12-84 months (1-7 years). after 84 months girls become taller than boys (figure 2). however, the smooth curve plot in figure 2 doesn’t show where the rate of change was accelerated or decelerated. in order to identify where rapid and slow rate of change lies we have used height growth velocity curves presented in figure 3. height growth velocity height growth velocity was calculated to investigate time of accelerated and decelerated growth periods. to assess these curvatures, the following velocity formula used (grajeda et al., 2016): )( ijtheight = height change for thi individual at thj measurement period. between 60 to 84 months, boys and girls had shown very similar rate of growth change. after 84 months (7 years) rate of change in girls became accelerated than boys. the growth difference in this time could be due to various factors. thus, we have used linear mixed effects models to identify factors associated with rate of change for both sexes. on the other hand, , )()( )( )1( )1()1( where tt theighttheight theight jiij jiji ij      east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 1-12 7 nonlinear mixed effects models were used to estimate height at maximum growth and rate of change over time within and between subjects. figure 3: smooth line and growth velocity curves by sex linear fixed and mixed effects models table 2 presents the goodness of fit test for the linear models. linear mixed effects model better fit the data than fixed effects model. table 2: assessing the goodness of fit of linear models fit statistics linear fixed linear mixed aic 44485.57 43010.67 log.lik -24546.60 -21446.34 the estimated values of the mixed effects model are presented in table 3. within an individual growth variation over time was around 0.03 cm. there was a positive relationship between within-individual rate of change (slope) and height at the baseline (random intercept). this points that a child who was taller at the baseline shown faster growth over time (r = 0.728). there was a positive correlation between two consecutive measurements taken on the same subjects at different measurement occasions (ar (1): = 0.2) (table 3). table 3: estimated values of random effects model random components estimates serial correlation continuous ar(1) st. dev. correlation (intercept) 1.893 (intr) = 0.2 age in months 0.0299 0.728 residual = 4.664 access to quality drinking water, mother’s educational status and sex had a significant effect on height growth. children who had access to quality drinking water were 3.8 cm east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 1-12 8 taller than children who had no access to quality drinking water (table 4). table 4: estimated values of different covariates on height growth of children aged 1-12 years based on the linear mixed effects model covariates categories β std.error df t-value p-value (intercept) 66.97115 2.618180 5067 25.57927 0.0000 age 0.49914 0.007732 5067 64.55163 0.0000 sex male (ref.) female -1.30927 1.348283 1698 -0.97106 0.3317 birth order -0.01189 0.042960 1698 -0.27685 0.7819 bcg status yes (ref.) no -0.21590 0.244046 1698 -0.88469 0.3765 had quality drinking water: no (ref.) yes -3.86616 0.748315 5067 -5.16649 0.0000 household size 0.24943 0.132781 5067 1.87850 0.0604 had anc visit no (ref.) yes 0.20970 0.225077 5067 0.93170 0.3515 breast feeding duration never fed (ref.) fed for 1-3 months 0.48811 2.516145 1698 0.19399 0.8462 fed for 4-6 months 2.07767 2.539510 1698 0.81814 0.4134 fed for > 6 months 1.48964 2.419669 1698 0.61564 0.5382 mother’s age at birth -0.00786 0.019595 1698 -0.40107 0.6884 father’s education: no education ref. elementary (1-8) 1.70812 0.210840 5067 8.10153 0.0000 0ther -1.52816 3.234500 5067 -0.47246 0.6366 mother’s education: no education ref. elementary (1-8) 0.83562 0.233946 5067 3.57187 0.0004 >= high school 1.93923 0.290056 5067 6.68570 0.0000 region addis ababa ref. amhara -1.60553 1.437172 5067 -1.11714 0.2640 oromia -4.24911 1.382365 5067 -3.07380 0.0021 snnp -1.19146 1.384214 5067 -0.86074 0.3894 tigrai -2.45187 1.403808 5067 -1.74658 0.0808 area of residence urban ref. rural -0.72144 0.436144 5067 -1.65413 0.0982 interaction effects age*sex male (ref.) female 0.02708 0.007462 5067 3.62902 0.0003 quality drinking water*region a.a (no ref.) amhara 2.17289 0.919798 5067 2.36236 0.0182 oromia 6.04705 0.928457 5067 6.51301 0.0000 snnp 2.99661 0.911643 5067 3.28704 0.0010 tigrai 2.14791 0.907350 5067 2.36724 0.0180 age*had quality drinking water (no ref.) yes 0.03497 0.008313 5067 4.20725 0.0000 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 1-12 9 mother’s educational status also plays a significant role on height growth of children. children whose mother had elementary (1-8) and high school plus educational status were 0.84cm and 1.9 cm taller than children whose mother had no formal education, respectively. as age increased by a month, girls’ height increased by 0.27 cm compared to boys holding other covariates constant in the model. the interaction effect between age and sex was higher in girls compared to boys. height in girls increased by 0.035 cm than boys as age increased by one month. on the other hand, access to quality drinking water had a significant effect on height growth of children (table 4). children those who had access to quality drinking was had 0.035 cm increased height compared to children those who had no access to quality drinking water. nonlinear models after identifying the best model fit to the data, the average rate of change over time and maximum (adult height) estimated height for both sexes separately. table 5: goodness of fit test for nonlinear mixed effects models by sex models fit statistics fixed effects models random effects male female male female gompertz aic 23759.5 21781.9 4243.28 2902.96 bic 23799.2 21798.4 4280.23 2956.96 logistic aic 23784.4 21772.6 4216.93 2921.48 table 6: estimated values and fit statistics based on nonlinear mixed effects growth curve models by sex female nonlinear mixed models fixed estimate random components fit statistics paramete r estimated std.err ó ó ó aic bic gompertz b1 179.44 2.398 -0.889 10.582 0.049 0.374 0.718 2901.48 2934.96 b2 1.054 0.0108 b3 0.0105 0.0003 logistic b1 166.703 1.716 -0.802 9.750 0.103 0.758 0.752 2922.96 2956.44 b2 1.623 0.0215 b3 0.0156 0.0003 b3 0.0087 0.0003 male gompertz b1 171.652 1.3951 -0.879 7.9496 0.039 0.227 0.717 4216.93 4253.88 b2 0.98945 0.0066 b3 0.0111 0.0002 logistic b1 161.340 1.034 -0.802 7.2219 0.047 0.340 0.995 4243.28 4280.23 b2 1.4912 0.0125 b3 0.01618 0.0002 10 model comparisons incorporating an individual-specific rate of change over time in the nonlinear models had dramatically reduced the estimation error and increased the fitting performance of the model. for instance, when adult height, rate of change and scaling (point of growth change) allow to varying across individuals, the fitting performance of the models had improved (table 6). random effects parameters were selected based on their capability to map with theoretical and physical meanings. when adult height and rate of change vary across individual over time, logistic models better fitted the data for both sexes. the mean adult height was estimated to be 166.7 cm and 171.6 cm in girls and boys, respectively. adult height and rate of change had inverse relationship for both sexes (for girls r13, = -0.802; for boys r13 = -0.879). discussion this study was aimed to model individual specific growth spurt over time in children aged 1-12 years old. the mixed effects models were applied to the height growth measurements to interpolate growth spurt within and between subjects over time. the effect size of different covariates on height growth was estimated using the linear mixed effects models. decelerated and accelerated growth periods were identified using growth velocity curves. the fitting performance of the models increased when adult height and rate of change were allowed to as individual specific. random effects were partitioned into between (σ) and east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 1-12 within (σ) subject variations. the consistent result by other study (spyrides et al., 2008) reported that considering random effects in the proposed models increase the precision of estimated parameters since parameters vary from individual to individual that might be demanded using margin of errors in the fixed effects model set-up. however, most of the mixed effects models applied to human physical growth data had no clear identification towards random and fixed effects parameters that should be included in the models. thus, one of the objects of this study was to identify model that best fits height growth in the defined time points when individual specific effects were taken in to account. in addition, this study was concerned to identify mixed effects parameters that best map on theoretical basis having biologically meaningful interpretations. of course, here the study was concerned to use some notations suggested by browne and co-authors (browne et al., 2002) to identify those parameters and to select best fit to the data. the authors discussed their arguments that many measures of model fit, even the likelihood ratio chi-square, and often appear to reflect relatively poor fit: this suggest a poor fit despite the model closely fitting the data. therefore, this study had carefully examined and identified that adult height and rate of change over time were individual specific and had random effect on height growth. the present study found that rapid growth was observed in children between 1 to 3 years followed by decelerated rate of change. other consistent study reported that children of both sexes grow at approximately the same rate until the adolescent growth spurt (rogol et al., 2000). adult height and rate of change had inverse relationship for both sexes. the consistent east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 1-12 11 findings reported that the adolescents with a later aphv tended to have a higher height later in life (chen et al., 2022). the interaction effect of age on rate of change in growth was higher in girls compared to boys. this may be due to girls experience adolescence earlier than boys. conclusions the logistic mixed effects models best fit and captured height growth pattern for both sexes. boys were taller than females until onset of puberty. the most decelerated rate of growth was observed in early childhood period for both sexes. mother’s educational status, access to quality drinking water, age and sex could be one of the determinant factors of height growth in children aged 112 years. rate of change at the base line had no a significant effect on adult height. child whose growth was accelerated during childhood period attains adult height later in life. competing interest authors have no conflict of interest acknowledgement we, the authors, would like to thank oxford university and young live ethiopia for the data access. references aggrey s. e. 2002. comparison of three nonlinear and spline regression models for describing chicken growth curves. poult. sci. 81:1782-1788. aggrey s. e. 2009. logiatic nonlinear mixed effects models for estimating growth parameters. poult. sci. asso. 88:276-280. agudelo gómez d. a., cerón muñoz m. f. and restrepo betancur l. f. 2008. modeling of growth functions applied to animal production. rev. colomb. cienc. pecu. 21:3-8. bates d., mächler m., bolker b. and walker s. 2015. fitting linear mixed-effects models using lme4. j. stat. softw. 67(1) 1–48. browne m., maccallum r. c., kim c.t., andersen b. l. and glaser r. 2002. when fit indices and residuals are incompatible. psychol. methods 7:403–421. chen l., su b., zhang y., ma t., liu j., yang z., li y., gao d., chen m., ma y., wang x., wen b., jiang j., dong y., song y., ma j. 2022. association between height growth patterns in puberty and stature in late adolescence: a longitudinal analysis in chinese children and adolescents from 2006 to 2016. front endocrinol (lausanne). 13:882840. chirwa e. d., griffiths p. l, maleta k., norris s. a, and cameron n. 2014. multilevel modeling of longitudinal child growth data from birth to twenty cohorts: a comparison of growth models. ann. hum. biol. 41 (2): 168-179. craig b. a. and schinckel a. p. 2001. nonlinear mixed effects model for swine growth. prof. anim. sci. 17(4): 256–260. davidian m. and giltinan d. m. 1995. nonlinear models for repeated measurement data. london: chapman & hall. pp 125. galeano-vasco l., cerón-muñoz m.f. and narváezsolarte w.v. 2014. ability of non-linear mixed models to predict growth in laying hens. revista brasileira de zootecnia 43: 573-578. goldstein h, browne w, and rasbash j. 2002. multilevel modelling of medical data.stat.med; 21: 32913315. goldstein h. and de stavola b. 2010. statistical modelling of repeated measurement data. longitudinal and life course studies; 1: 170-185. goldstein p. h. 1998. multi-level repeated measures growth modelling using extended spline functions. stat. med. 17(23):2755– 2770. grajeda l. m., ivanescu a., saito m., crainiceanu c., jaganath d., gilman r. h., crabtree j. e., kelleher d., cabrera l., cama v. and checkley w. 2016. modelling subject specific childhood growth using linear mixed effect models with cubic regression splines. emerg. themes. epidemiol. 13(1). doi: 10.1186/s12982-015-0038-3. grimm k. j., ram n. and hamagami f. 2011. nonlinear growth curves in developmental research. child dev. 82: 1357–1371. grossman m. and koops w. j. 1988. multiphase analysis of growth curves in chickens. poult. sci. 67:33-42. east afr. j. biophys. comput. sci. 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(2008) effect of predominant breastfeeding duration on infant growth: a prospective study using nonlinear mixed effect models. j pediatr (rio j). 84(3):237-43. tanner j. m. 1981. a history of the study of human growth. cambridge university press; who: physical status: the use and interpretation of anthropometry, report of a who expert committee 1995. wang z. and zuidhof m. j. 2004. estimation of growth parameters using a nonlinear mixed gompertz model. poult. sci. 83: 847–852. zemel b. s. and johnston f. e. 1994. application of the preece-baines growth model to cross-sectional data: problems of validity and interpretation. am. j. hum. biol. 6 (5): 563–570. . introduction mathematical model formulation the modified mathematical model model formulation qualitative analysis of the modified model well-posedness steady state basic reproduction number local stability of disease free equilibrium global stability of disease free equilibrium endemic equilibrium point local stability of endemic equilibrium bifurcation analysis sensitivity analysis numerical simulations and discussion extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction preliminaries intuitionistic fuzzy set operations over intuitionistic fuzzy sets multi-objective programming problem mathematical formulation of problem intuitionistic fuzzy multi-objective linear decision-making problem intuitionistic fuzzy goal model of if-moldmp proposed solution method extended yager-membership function in the ifde develop a new intuitionistic fuzzy (if) aggregation operator the intuitionistic fuzzy goal programming method interactive penalty function method (ipfm) algorithm for penalized ifgp method numerical example results and discussion conclusion introduction mathematical model formulation the modified mathematical model model formulation qualitative analysis of the modified model well-posedness steady state basic reproduction number local stability of disease free equilibrium global stability of disease free equilibrium endemic equilibrium point local stability of endemic equilibrium bifurcation analysis sensitivity analysis numerical simulations and discussion extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion east east afr. j. biophys. comput. sci. (2023), vol. 4, issue. 1, 28-41 *corresponding author: email: buchale.shishitu@yahoo.com https://dx.doi.org/10.4314/eajbcs.v4i1.3s buchale shishitu shija*, and atnafu w/yohans firew fisheries and aquaculture, southern agricultural research institute (sari), arba minch agricultural research center, p.o.box 2228, arba minch, ethiopia keywords: ayalew reservoir; cohort analysis; condition factor; cyprinus carpio; length-weight relationship; population dynamics parameters abstract common carp (cyprinus carpio) is an imported fish species in ayalew reservoir. the study was intended at estimating important population dynamics parameters and production potential in the reservoir. total length (tl) and total weight (tw) data were collected from a total of 276 fish samples (141 females and 135 males). the obtained data were analyzed using fisat ii software. the population and production potential were assessed by using jones length based cohort analysis model and length-based thompson and bell yield prediction models. the average total length was 26 cm and the dominant length groups ranged from 17 to 33 cm were 87%. the length-weight relationship parameters were (tw = 0.0565tl2.53, r2 = 0.95) and the condition factor k = 1.29. the parameters of von vertalanffy growth curve were l∞ = 41 cm, k = 0.52, to = -0.29, θ = 2.9 and a0.95 = 5.5 years. the assessed values of the total, natural and fishing mortalities were z = 1.23, m = 0.55 and f = 0.68, respectively. the current exploitation rate, 0.55, indicates slightly overexploitation. the estimated fish population and the annual fish yield were 59,304 and 1.5 tons, respectively. however, investigation on reproductive biology, limnolocal aspects and stock enhancements should be required for the sustainability of these resources. introduction common carp (cyprinus carpio) is considered to be a very important aquaculture species in many asian and some european countries. it is widely distributed and frequently considered a nuisance species outside its native range (penne and pierce, 2008; mohammad, 2015). the common carp is one of the most common freshwater fish invaders worldwide, creating adverse effects on water quality and impacting ecosystem structure and function (letvin et al., 2017). it is highly adaptable to new environments and can alter the biotic and abiotic integrity of aquatic ecosystems (bajer et al., 2012). east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx population dynamics and yield estimation of common carp (cyprinus carpio, linnaeus, 1758) in ayalew reservoir, gamo zone, southern ethiopia research article mailto:buchale.shishitu@yahoo.com https://dx.doi.org/10.4314/eajbcs.v4i1.3s east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 29 in ethiopia, cyprinus carpio was first introduced to aba samuel dam (awash river basin) in 1940 from italy (getahun, 2017). later, it has been introduced in lake ziway in the late 1980s (fao, 1997; abera et al., 2015). for food security purpose, c. carpio was introduced in highland lakes such as ashengie, ardibo, and maybar and the introduction was successful (golubtsov and darkov, 2008). ayalew reservoir is one of the highland water bodies in gamo zone chencha woreda. according to gathered information from chencha woreda, c. carpio was introduced in ayalew reservoir in the late 1980s by national fishery and aquatic life research center. after some years later, the fish was adapted and has been observed by the local community in the reservoir. since then, there was no any documented information about the population dynamics of c. carpio in ayalew reservoir. for sustainable management and utilization, information on the population dynamics and production potential is very important for this species. therefore, the objective this study was to estimate the population dynamics and production potential of c. carpio in the reservoir. materials and methods description of the study area ayalew reservoir is found in chencha woreda in gamo zone. it is situated at the coordinates of 06°25′068″n latitude and 037°57′368″e longitude with an elevation of 2861 meters above sea level. the area of the reservoir is about 4.37 ha or 0.0437 km2 with a maximum depth of 5.3 meters. . figure 1. location of ayalew reservoir in chencha woreda, gamo zone, southern ethiopia east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 30 methods of sampling and data collection ten youths were trained about fish catching and data recording systems. for the trained youths a boat and four monofilament gill nets with 3.5 mesh sizes were delivered for the research activities. two data collectors were selected based on their skill and involved in data collecting process. the gillnets were deployed with plastic bottles as floats across the reservoir at 5:00 pm and collected at 7:00 am the next morning. immediately following capture, the total length (tl) and weight (tw) of the fish were measured, using a measuring board and sensitive balance, to the nearest 0.1 cm and 1 g, respectively. data were collected weekly for eight months, from october 2021 to may 2022. length-weight relationship and condition factor length-weight relationship was calculated using power function (le cren, 1951). tw = 𝑎𝑇𝐿𝑏-----------------------------------------[1] where, tw = total weight (g), a = the intercept, tl = total length (cm), b = the slope of length-weight regression the fulton’s condition factor (k) is often used to reflect the nutritional status or well-being of an individual fish. it was calculated by using the formula described by fulton (1904) which indicated below. k = 𝑇𝑊 𝑇𝐿3 ∗ 100----------------------------------------[2] where, k = fulton’s condition factor tw = total weight of fish in gram (g) tl = total length of fish in centimeter (cm) data summarization and analysis catch data were compiled and summarized in a format suitable for the jones length-based cohort analysis and the length-based thompson and bell yield prediction models. microsoft office excel (2010) was employed for both data summarization and subsequent analysis. estimating growth parameters the k-scan technique available in the elefan i module of the fisat ii software was utilized to estimate asymptotic length (l∞) and growth rate (k) from the length-frequency data. pauly's empirical formula (1979) was then applied to calculate the theoretical age at length zero (t0) log (–to) = –0.392 – 0.275*log l∞–1.038*log k ---------------------------------------------------------------[3] where, to = is the theoretical age at which fish would have at zero length. l∞ = asymptotic length, k = von bertalanffy growth rate constant growth performance indexes were calculated as munro and pauly (1983): θ = log(k) + 2 × log(l∞) ----------------------[4] where, θ = growth performance index the length at first maturity (l50) was computed as froese and binohlan’s (2000) equation: log(l50) = 0.8979 × log(l∞) – 0.0782 ------------[5] east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 31 estimating mortality parameters based on length composition data for the estimation of total mortality rates, linearized length converted catch curve method was applied and the mortality parameters were calculated based on the following formula (pauly, 1984). ∆t = 1/k*ln[(l∞ l1)/[(l∞ l2)] -----------------[6] t (l1+l2)/2 = -1/k{ln[(1-(l1+l2)/2/(l∞)] --------[7] ln{[c(l1, l2)]/[∆t(l1, l2)]} = az*t(l1+l2)/2 ---[8] where: ∆t = is age interval between l1 and l2 or the time taken by fish of length l1 to reach length l2 t(l1+l2)/2 = age of the average consecutive length groups (x variable) ln{[c(l1,l2)]/[∆t(l1, l2)]} = y variable the natural mortality coefficient (m) was estimated using taylor’s method (1958) as follows: m = -ln(1-0.95)/a0.95-----------------------------[9] where, a0.95 = longevity, the age at which 99% of the cohort would be dead as a result of natural means (spare and venema, 1997). a0.95 = to+2.996/k ------------------------------[10] where, to = is the theoretical age at which fish would have at zero length; k = von bertalanffy growth rate constant to obtain total mortality, regression analysis was conducted between x and y variables as described in formula 7 and 8, respectively. total mortality (z) = fishing mortality (f) + natural mortality (m) ---------------------------------------[11] then, the fishing mortality rate (f) was obtained by subtracting m from z. estimating population sizes and fishing mortalities by length group (jones, 1984) jones length-based cohort analysis model was used to estimate the population size and fishing mortality coefficient of c. carpio by length groups. this was done in the following three steps: i) population number estimate of the largest length group in the catch. n(largest l) = c(largest l)*(z largest l/f largest l ) ----------------------------------------------------[12] where, n (largest l) = the population of the largest length group in the catch; c(largest l) = the catch of the largest length group; z(largest l) = the total mortality rate of the largest length group in the catch; f(largest l) = the fishing mortality rate of the largest length group in the catch; c(l1, l2) = the catch of the length groups of n(l1) ii) population numbers estimate of consecutively younger length groups in the catch. n(l1) = [n(l2) * h(l1, l2) + c(l1, l2)] * h(l1, l2) ---------------------------------------------------------[13] where, n(l1) = the population number of l1 (younger) fish n(l2) = the population number of l2 (older) fish east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 32 h(l1, l2) = the fraction of n(l1) fish that survived natural death as it grows from length l1 to l2 and computed as the following equation (jones, 1984). h(l1, l2) = [(l∞ l1)/ (l∞ l2)] (m/2k) ------[14] where, l∞ = the asymptotic length (cm) of c. carpio attained at mature size; l1 and l2 = consecutive length groups of fish (cm) that contributed to the fishery; k = von bertalanffy growth rate constant (yr-1); m = the rate of natural mortality coefficient iii) fishing mortality rate estimate of the respective length groups. fishing mortality values for each length group was estimated using the equation as follows: f(l1, l2) = (1/∆t) * ln[n(l1)/n(l2)] – m -------[15] where, f(l1, l2) = fishing mortality coefficient pertaining to the respective length group; n(l1), n(l2) and m are as defined above. to know the status of the stock, the exploitation rate (e) was estimated from mortality parameters as: e = f/z. the exploitation rate (e) equal to 0.5 is considered as optimum level of exploitation; whereas less than 0.5 refers to under exploitation and greater than 0.5 refers to overexploitation (gulland, 1971). thompson and bell (1934) yield prediction procedure step 1) estimating the total annual yield obtained under the current level of fishing i) estimating the yield obtained per year from each length group yield from each length group obtained per year (y(l1, l2) is catch in number per length group per year (c(l1, l2) multiplied by the average weight of each length group i.e., y(l1, l2) = c(l1, l2) * w(l1, l2) --------------[16] where, y(l1, l2) = the yield (weight) of fish obtained per year from respective length group; c(l1, l2) = total annual catch of fish obtained from respective length group; w(l1, l2) = the mean weight of each length group estimated using equation w(g) = a* lb ---------------------------------------[17] where, w(g) = the average weight of each length group, l = the average length (cm) of each length group i.e., l = (l1+l2)/2 in which l1 and l2 are the length intervals of consecutive length groups. ‘a’ and ‘b’ are values of the regression coefficients. ii. estimated yield was obtained from all length groups per year by adding up the contribution of each length group. results and discussion length-weight relationship and fulton’s condition factor the values of the regression coefficient “b” for females (n =141), males (n =135) and combined sexes (n =276) obtained from the length-weight relationship by using the best-fit regression of power function gave 2.51, 2.47 and 2.53, respectively (fig. 2). analysis of variance (oneway anova) showed the significant differences between the regression coefficient “b” and the cubic value of “b” (3) (p < 0.05). east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 33 as indicated in table 1, the t-test also revealed that the presence of significant difference between the regression coefficient “b” in female, male and combined sexes (p < 0.05). females tw = 0.0611tl2.51 r² = 0.9418 n = 141 0 100 200 300 400 500 600 700 0 10 20 30 40 50 t o ta l w ei g h t (g ) males tw = 0.0664tl2.47 r² = 0.9324 n = 135 0 100 200 300 400 500 600 0 10 20 30 40 50 t o ta l w ei g h t (g ) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 34 figure 2. length-weight relationship of c. carpio from ayalew reservoir in this study, the length-weight relationship showed that c. carpio showed a negative allometric growth. values of b equal to 3 indicate that the fish grows isometrically; values other than 3 indicate allometric growth (tesch, 1971). the b value is often 3.0 and generally between 2.5 and 3.5 (froese, 2006). the b values in fish is species specific and therefore varies with sex, age, seasons, physiological conditions, growth increment and nutritional status of fish (ricker, 1975; bagenal and tesch, 1978). mert and bulut (2014), saylar and semra (2014), yilmaz et al. (2012), ünver and yildirim (2011), and richard et al. (2018) also reported negative allometric growth for c. carpio in different water bodies worldwide, and their b values were 2.9, 2.8, 2.83, 2.89 and 2.75, respectively. however, positive allometric growth values for this species were documented by (karataş et al., 2007; kirankaya and ekmekçi, 2004), who reported b values of 3.21 and 3.022, respectively. the difference in the results of the current and previous publication might possibly be associated with reasons related to ecosystem and biological phenomena such as seasons, feeding behavior, cmpetition for fd, and maturity stages. table 1. regression static parameters of c. carpio. parameters female male combined a value 0.0611 0.0664 0.0565 b value 2.5135 2.4698 2.5303 std. error (sb) 28.61 30.05 29.58 r2 0.9418 0.9324 0.9451 t-calculated 48.62 42.55 69.26 t-critical (5%) 1.97 1.97 1.97 no of observation 141 135 276 significance 0.000 0.000 0.000 combined tw = 0.0565tl2.53 r² = 0.9451 n = 276 0 100 200 300 400 500 600 700 0 10 20 30 40 50 t o ta l w ei g h t (g ) total length (cm) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 35 monthly mean fulton’s condition factor (k) ranged from 1.15 to 1.39 for females, 1.16 to 1.44 for males and 1.23 to 1.38 for combined sexes (table 2). the average k value for females, males and combined sexes were 1.28, 1.30 and 1.29, respectively. females exhibited their lowest condition factor (1.15) in february and their highest (1.39) in may. in contrast, the lowest value for males (1.16) was recorded in november, and the peak value (1.44) occurred in april. for combined sexes, the minimum value (1.23) was recorded in november and the highest (1.38) in april and may. fulton’s condition factor indices have been widely used as indicators of relative health and depend on the environmental conditions and food availability. april and may are highly rainy season in the study area and might be the reason for the variation in monthly condition factor. the results indicated that there was no significant difference between sexes as well as month’s interaction in mean condition factor of c. carpio (p > 0.05). table 2.the mean monthly fulton’s condition factor of female, male and combined c. carpio in ayalew reservoir. moths female male combined october 1.28 1.21 1.25 november 1.33 1.16 1.23 december 1.23 1.30 1.26 january 1.28 1.38 1.33 february 1.15 1.32 1.25 march 1.22 1.25 1.24 april 1.32 1.44 1.38 may 1.39 1.36 1.38 average 1.28 1.30 1.29 morton and routledge (2006) divided the k values into five categories as very bad (0.8–1.0), bad (1.0–1.2), balance (1.2–1.4), good (1.4–1.6) and very good (> 1.6). on the other hand, ayoade (2011) suggests that the fulton’s condition factor higher than one is a good fish health condition. based on the five categories above, the condition factor in the present study was not in the range of 1.4-1.6 and c. carpio in the reservoir was not in a good health condition. this might be due to anthropogenic factor that affects the limnological aspects of the reservoir. the length cmpsition of sampled catch and estimated annual catch of c. carpio the mean total length catch composition and yield contribution of c. carpio are indicated in fig. 3. the compositions were ranged from 13 to 39 cm with an average length of 26cm. the mean length ranged from 17 cm to 33 cm were about 87% of the total catch and had a high contribution in fish yield. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 36 figure 3. size structure of c. carpio harvested from ayalew reservoir estimation of growth and mortality parameters the estimated asymptote length (l∞) and the length at first maturity (l50) were 41 cm and 23.44 cm, respectively. the annual growth constant (k) and the growth performance index phi (θ) were 0.52 yr-1 and 2.9, respectively (fig. 4). the theoretical age at which fish would have at zero length (to) was -0.29 and the longevity (a0.95), the age at which 99% of the cohort would be dead as a result of natural means was 5.5 years. the fish species with a growth constant (k) value greater than or equal to one (1) is a fast growing fish species (gulland, 1983; sparre and venema, 1998). besides the genetic makeup which determines the growth potential of the fish species, food availability, environmental conditions and fishing effects could affect the growth performance index of a particular fish species (getabu, 1992). according to sambo and haruna (2012), the growth performance index is a function of l∞ in which increase in l∞ leads to an increase in the growth performance index. the growth constant (k) value ranges from 0.06 to 0.48, 0.12 to 0.75 and 0.11 to 0.69 for c. carpio species that live naturally in rivers, lakes and reservoirs, respectively (fish base, 2011). the growth constant (k) of c. carpio in ayalew reservoir was 0.52 yr-1and laid into the range of 0.11-0.69 for the c. carpio fish populations that live naturally in water of reservoirs. 0 2 4 6 8 10 12 14 13 15 17 19 21 23 25 27 29 31 33 35 37 39 c at ch c o m p o si ti o n ( % ) mean total length (cm) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 37 figure 4. elefan i kscan routine fisat ii output for c. carpio from ayalew reservoir. a length composition data prepared for a linear regression analysis was established between x and y variables for estimation of total mortality (table 3). table 3. parameters for length-based catch curve analysis length group (cm) annual catch c(l1,l2) x y k l∞ (cm) ∆t (l1,l2) (l1+l2)/2 t(l1+l2)/2 ln(c(l1,l2)/∆t) 16-18 859 0.52 41 0.16 17 1.03 8.59 18-20 967 0.52 41 0.17 19 1.20 8.62 20-22 859 0.52 41 0.19 21 1.38 8.40 22-24 564 0.52 41 0.21 23 1.58 7.88 24-26 591 0.52 41 0.24 25 1.81 7.81 26-28 967 0.52 41 0.28 27 2.07 8.16 28-30 644 0.52 41 0.32 29 2.36 7.60 30-32 591 0.52 41 0.39 31 2.71 7.33 32-34 483 0.52 41 0.48 33 3.14 6.91 34-36 349 0.52 41 0.65 35 3.70 6.29 36-38 107 0.52 41 0.98 37 4.48 4.69 38-40 81 0.52 41 2.11 39 5.81 3.64 based on the linearized length-based catch curve analysis, the mortality parameters were estimated. as indicated in figure 5, the slope of the regression line (b) is -1.23 and hence, the estimated total mortality rate (z) was 1.23 yr-1. out of the total mortality, natural mortality rate (m) and fishing mortality rate (f) were 0.55 yr-1 and 0.68 yr-1, respectively. using these mortality estimates, the exploitation rate (e) was computed as 0.55 and indicates that the c. carpio is slightly overexploited. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 38 based on the computed exploitation rate (e), the c. carpio in ayalew reservoir was overexploited and the fish population was not abundant enough to utilize the resource sustainably. the exploitation rate (e) of a fish stock is at its maximum level and sustainable if the value of f was equivalent with or same with the value of m or the rate of exploitation (e) had value of 0.5 (gulland, 1983). figure 5. linearized length-based catch curve of c. carpio from ayalew reservoir estimated population sizes and current yield by length group the estimated population number and annual yield of c. carpio in the study area were about 59, 304 and 1.5 tons, respectively (table 4). the recruitment pattern of the fish was year-round with two peak recruitment period in the year. the peak recruitment takes place twice a year, in april and july to august for this particular fish species (figure 6). the projected annual recruitment of c. carpio in the reservoir was about 9,118 as indicated in table 4 (column 8; row 3). based on the estimated population, it is possible to obtain about 7.4 tons of fish biomass and 1.5 tons of fish yield per year. y = -1.2259x + 10.586 r² = 0.9805 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 l n (c (l 1 ,l 2 )/ ∆ t) average age t(l1+l2)/2 east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 39 figure 6. recruitment pattern output from fisat ii for c. carpio in ayalew reservoir table 4. estimated population, current yield and other parameters of c. carpio by length group length group (cm) annual catch x y ∆t (l1,l2) (l1+l2)/2 t(l1+l2)/2 ln(c(l1,l2)/∆t) h n(l1,l2) current yield (kg) 12-14 161 0.14 13 0.73 7.07 1.01 9118 6 14-16 322 0.15 15 0.88 7.69 1.01 8774 18 16-18 859 0.16 17 1.03 8.59 1.01 8264 64 18-20 967 0.17 19 1.20 8.62 1.01 7220 95 20-22 805 0.19 21 1.38 8.34 1.01 6081 102 22-24 564 0.21 23 1.58 7.88 1.02 5115 89 24-26 591 0.24 25 1.81 7.81 1.02 4400 115 26-28 940 0.28 27 2.07 8.14 1.02 3665 222 28-30 644 0.32 29 2.36 7.60 1.02 2597 182 30-32 591 0.39 31 2.71 7.33 1.03 1847 197 32-34 483 0.48 33 3.14 6.91 1.04 1170 189 34-36 295 0.65 35 3.70 6.12 1.05 623 134 36-38 107 0.98 37 4.48 4.69 1.08 284 56 38-40 81 2.11 39 5.81 3.64 1.17 146 48 total 7,410 59,304 1,517 east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 28-41 40 conclusions & recommendations the growth pattern of c. carpio was negative allometric which implied that the fish became thinner as its body length increases. the wellbeing of the fish was not in a good health condition. the mean length groups ranged from 17 cm to 33 cm was about 87% of the total catch and had a high contribution in fish yield. the c. carpio in ayalew reservoir can grow up to the maximum length (l∞) 41 cm with growing speed (k) of 0.52 per year. the long lifespan (a0.95) of the cohort and the length at first maturity were 5.5 years and 23.44 cm, respectively. the production potential of the fish was about 7.4 tons of fish biomass and 1.5 tons of yields per year. however, investigation on reproductive biology, limnological aspects and stock enhancement are required in the reservoir. acknowledgements the authors would like to highly acknowledge the southern agricultural research institute (sari) for the financial support, arba minch agricultural research center for allowing access to the necessary facilities and arba minch agricultural research center staff members for their valuable assistance during the execution of the experiment. conflicts of interest the authors declare that there is no conflict of interest in publishing the manuscript in this journal. references abera l., getahun a. and lemma b. 2015. some aspects of reproductive biology of the common carp (cyprinus carpio linnaeus, 1758) in lake ziway, ethiopia. glob. j. agric. agric. sci. 3(3): 151–157. ayoade a.a. 2011. length-weight relationship and diet of african carp labeoogunensis (boulenger, 1910) in asejire lake southwestern nigeria. j fish aquat sci. 6: 472-478. bagenal t.b. and tesch f.w. 1978. age and growth. in: bagenal tb (ed) methods for assessment of fish production in fresh waters. blackwell science publications, oxford, pp 101-136. bajer p.g., chizinski c.j., sillbernagel j.j. and sorensen p.w. 2012. variation in native micropredator abundance explains recruitment of mobile invasive fish, the common carp, in a naturally unstable environment. biol. invasions. 14(9):1919– 1929. fish base 2011.growth parameters for cyprinuscarpio http://www.fishbase.org. froese r 2006. cube law, condition factor, and weightlength relationships: history, metaanalysis, and recommendations. j appl. ichthyol 22:241–253. froese r. and binohlan c. 2000. empirical relationships to estimate asymptotic length, length at first maturity and length at maximum yield per recruit in fishes, with a simple method to evaluate length frequency data. j. fish biol. 56: 758–773. doi: 10.1111/j.10958649.2000.tb00870.x fulton t.w. 1904. the rate of growth on fishes. twentysecond annual report, part iii. fisheries board of scotland, edinburgh.pp.141-241. getabu a. 1992. growth parameters and total mortality in oreochromis niloticus (linnaeus)from nyanza gulf, lake victoria. hydrobiologia 232: 91-97. getahun a. 2017. the freshwater fishes of ethiopia, diversity, and utilization. addis ababa: view graphics and printing plc. pp. 349. golubtsov a.s. and darkov a.a. 2008. a review of fish diversity in the main drainage systems of ethiopia based on the data obtained by 2008, ecological and faunistic studies in ethiopia, pavlov d.s. et al. 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(2024), vol. 5, issue. 1, 40-50 staphylococcus aureus in bovine mastitis: prevalence and risk factors in small holder dairy farms located in and around hawassa, ethiopia nebyu mje 1* , birtukan abebaw 2 1college of veterinary medicine & agriculture, addis ababa university, p.o.box 34, bishoftu, ethiopia 2faculty of veterinary medicine, hawassa university, p.o.box 05, hawassa, ethiopia keywords: california mastitis test (cmt); dairy cows; hawassa town; mastitis; staphylococcus aureus abstract mastitis is a widespread disease in dairy cattle that is known for its economic and public impact globally, including ethiopia. among others, staphylococcus aureus is frequently isolated bacterial pathogen from milks of mastitis positive dairy cows. this cross-sectional study, conducted from march to august 202l in and around hawassa, ethiopia, aimed to estimate the prevalence of mastitis, to identify s. aureus in bovine mastitis milk and explore the associated risk factors. from 29 smallholder dairy farms, 250 lactating cows were purposively selected and screened using clinical signs and the california mastitis test (cmt) to diagnose clinical and subclinical mastitis, respectively. a standard bacteriological study was performed on 127 mastitis-positive milk samples, and the resulting data were analyzed using stata (version 12), with significance set at p<0.05. the study findings indicated a mastitis prevalence of 50.8% at the cow level (4.8% clinical, 46% subclinical) and 27.4% at the quarter level (2.9% clinical, 24.5% subclinical). in the lgistic regressin model, cw’s age, lactation stage, and farm cleaning frequency were significantly assciated (p < 0.05) with mastitis. accordingly, highest odds of mastitis were recorded in cows ≥ 6 years old (odds ratio [or] =17.61, 95% confidence interval [ci] = 5.3, 58.44) and in farms less frequently cleaned (or= 5.1, 95%ci= 1.88, 13.71). staphylococcus aureus was identified in 47.2% (60/l27) of milk samples, and more frequently in subclinical (47.8%) than clinical (41.6%) cases. in conclusion, our study confirmed a high prevalence of mastitis in the study area, particularly subclinical cases associated with s. aureus. the detection of s. aureus in nearly half of the mastitic milk samples suggests the potential involvement of other pathogens, warranting further research to identify additional causative agents. these findings highlight the need for routine screening of cows for timely treatment control intervention, and community awareness creation activities. introduction mastitis, characterized by inflammation of the udder and teats, is a prevalent condition in dairy cattle. it can manifest in two primary forms: clinical and subclinical mastitis (ruegg et al., 2017; taponen et al., 2017). the disease is knwn for its damage to the udder tissue, which can happen in numerus mammalian species, east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx *corresponding author: email: nebhawas@gmail.com +251910248878 https://dx.doi.org/10.4314/eajbcs.v5i1.4s research article https://dx.doi.org/10.4314/eajbcs.v5i1.4s east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 40-50 41 mainly in domestic dairy animals. being under constant state of physiological stress and most productive nature, mastitis is the most frequent disease of highly producing dairy cattle and can be potentially fatal (gutierrez-chavez et al., 2019). bovine mastitis has been reported as the most critical disease on most dairy farms associated with reduction of farm profitability due to decreased milk yield and quality, decreased reduced reproductive performance, discarded milk, high costs of treatment, death of the affected cow, and forced culling of young cows (radostits et al., 2007; julian, 2016). subclinical mastitis (scm) is an inflammation of the mammary gland characterized by the absence of visible lesions in the udder or its secretions, despite the presence of pathogenic microorganisms and an elevated somatic cell count (scc) in the milk (smith, 1996; radostits et al., 2007). while both clinical and subclinical mastitis cause significant economic losses in the dairy industry, clinical mastitis remains a prevalent issue in many dairy herds (gezehagn et al., 2020). furthermore, mastitis poses a zoonotic risk due to the potential shedding of bacteria and toxins in milk. this complex disease is caused by diverse pathogens (mainly bacteria) that are commonly categorized epidemiologically as contagious or environmental. contagious pathogens, primarily reside in the udder of infected cows and spread from cow to cow during milking, tend to cause chronic subclinical infections with intermittent clinical flare-ups at times of stress (abebe et al., 2016). environmental bacteria, opportunistic organisms present in the cow's surroundings, typically cause shorter-term clinical infections (blowey and edmondson, 2010). diagnosis of subclinical mastitis often relies on indirect tests, such as somatic cell count (scc) and the california mastitis test (cmt), which measure the cellular response of the udder/cow to infection. cows with healthy udder usually produce milk that contain scc below 200,000 cells/ml, however, if the scc is over 400,000 cells/ml the udder should be considered as having an intramammary infection (idriss et al, 2013). during mastitis (particularly during scm), the presence of bacteria triggers an immune response, leading to increased migration of macrophages and neutrophils from blood into the milk, and a high scc. this is also accompanied by inflammation of the gland, damage to host defense system, and epithelial cells (douaa et al., 2016). the cmt, performed by mixing proportional amount of suspected milk with a reagent, detects increased leukocyte numbers by dissolving cell walls and releasing dna, resulting in a stringy gel formation proportional to the degree of infection (melleneger, 2001). based on the existing literatures, over 140 potentially pathogenic organisms (including bacteria, fungi, algae, mycoplasma, and nocardia) have been recorded as potential cause of cow mastitis. however, most bovine mastitis cases involves various bacterial pathogens, classified as contagious, teat skin opportunistic, or environmental (radostits et al., 2007). staphylococcus aureus is a frequent etiological agent incriminated for both subclinical and chronic infections, causing substantial economic losses in dairy farming (kubota et al., 2007). due to the increasing prevalence of mastitis, and calls to investigate its causes more thoroughly, this study aimed to determine the prevalence of both clinical and subclinical mastitis in smallholder dairy farms in and around hawassa town, east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 40-50 42 southern ethiopia, while isolating and identifying s. aureus from mastitic milk and identifying the associated risk factors. considering the number of studies already done on the isolation of s. aureus in ethiopia, this study aimed to update existing information and investigate if the epidemiology of the bacteria has changed. materials and methods study area the study was carried ut in and around hawassa city (fig. 1). hawassa, the capital city of the sidama region, is located at about 275 km suth of addis ababa. the city has a total of 157,879 inhabitants. hawassa city, lies between 7°03’l.35”n latitude and 38°29’43.81”e lngitude at an altitude of l750 meters above sea level. annually, the area receives an average of 800 l000 mm of rainfall, and an average annual temperature of 22°c and 5l.8% mean relative humidity. dry savanna and bush-type vegetation covers major part of the area. according to the central statistics authority (csa, 2020), the region comprises about 2,413,482 cattle, 308,903 goats, 467,858 sheep, 34,709 horses, 16,376 donkeys, 1,824,841 poultry, and 44,364 beehives. figure 1. study area map east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 40-50 43 study animals the study was carried out on lactating crossbred cows selected randomly from 29 small holder dairy farms and the associated risk factors were recorded on the sheet designed for it. host related risk factors such as age, parity, lactation stage, body condition score (bcs), and average milk yield per day, were properly recorded on data recording sheet designed for this purpose. the age of the study animals (cows) were determined based on dentition as per the recommendation of johnson (1998). whereas, body condition score (bcs) of the cows were estimated using the standard guide developed by sharad et al. (2016). for ease of data analysis and result presentation, the age classification was made into three as <3, 4 to 5 and > 6 years. moreover, the available records were used to collect data on the remaining hostrelated risk factors, including parity, lactation stage, and average milk yield per day. once the months of lactation is known, the cows were classified into three stages of lactation: early (first 3 months), mid (4 to 6 months), and late (7 months or more). study design a prospective cross-sectional study design was used to investigate the problem from march 2021 to august 2021. sample size determination thrusfield et al. (2017) formula was used to calculate the minimum sample size required for this study. accordingly, an expected prevalence of 81.1% (duguma et al., 2014), 95% confidence interval and a significance level of 5% were used and computed to be 236. although the minimum number of lactating dairy cows needed for the study was 236, we increased the sample size to 250. study methodology dairy cows were purposively selected from 29 smallholder farms located within and adjacent to the hawassa city administration to assess the prevalence and risk factors of mastitis. each selected lactating cow underwent screening for mastitis using clinical examination and the california mastitis test (cmt). cows exhibiting either clinical signs of mastitis or a positive cmt result were considered to have mastitis, and hence milk samples from these cows were collected for bacteriological culture. the primary aim of the culture was to identify the presence of staphylococcus aureus. moreover, farm visit (observation) and interviews with farm owners were conducted to gather relevant information on the putative risk factors for both clinical and subclinical mastitis, including host related risk factors (i.e. age, body condition score, parity, lactation stage, and daily milk yield), husbandry system, hygienic status of the farms, and past occurrences of mastitis within the herd. clinical inspection of the udder to diagnose clinical mastitis, the udders of all study cows were subjected to both visual inspection and palpation. special attention was given for indicators of acute or chronic inflammatory reactions, including: hardened (chronic) and swollen udder quarters, pain responses to udder palpation (manifested by kicking), localized heat and redness, and alterations in milk secretions such as the east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 40-50 44 presence of clots or flakes, a watery consistency, or blood tinge. california mastitis test california mastitis test (cmt) was used to detect subclinical mastitis. from each quarter of a suspected cow, a squirt of milk was dispensed into separate wells of the cmt paddle, followed by an equal amount of cmt reagent. the mixture was gently agitated, and the resultant gel formation, if there is any, was visually scored based on its thickness. accordingly, scores were assigned as follows: 0 (negative), t (trace), 1 (weak positive), 2 (distinct positive), and 3 (strong positive), reflecting the level of infection. quarters with a score of 1 or greater were classified as positive for subclinical mastitis, while those with a score of 0 were classified as negative (quinn et al., 2002) milk sample collection the teats of mastitis positive cows were properly washed and disinfected with 70% alcohol, and then approximately 10 ml of milk was collected aseptically into sterile bottle from each affected quarter after discarding few squirt (the initial three streams) of milk. the bottles were properly labeled, immediately placed in a chilled icebox containing ice packs and then transport to the veterinary microbiology laboratory at hawassa university. upon arrival, samples were stored at +4°c and held for no more than 24 hours prior to bacterial culture. isolation and identification bacteriological culture was made following the standard microbiological techniques (quinn et al., 2002). briefly, a loop-full of each milk sample was streaked onto sterile blood agar base (himedia, india) enriched with 5% sheep blood. plates were incubated aerobically at 37°c and examined after 24–48 hours for colony growth. colonies were initially characterized based on morphology, hemolytic pattern, and gram staining reaction. gram-positive colonies exhibiting a typical grape-like arrangement under microscopy were selected for further analysis. the selected colonies were subcultured onto nutrient agar plates (oxoid, uk) and incubated at 37°c for 24 hours. subsequently, a catalase test was performed using 3% hydrogen peroxide (h2o2). catalase-positive, gram-positive cocci were then subcultured onto mannitol salt agar (msa) and incubated at 37°c. after 24–48 hours, msa plates were examined for growth and color change. the presence of growth accompanied by a color shift from red to yellow on the msa (i.e. a change in the medium's ph) was considered presumptive evidence of salttolerant staphylococcus species (quinn et al., 2002). a tube coagulase test, following the method of robertson et al. (1999), was performed. fresh cultures of suspected staphylococci, grown in nutrient broth for 18-24 hours, were mixed with 0.5ml of 10 fold diluted sterile rabbit plasma (sigma). this mixture was incubated at 37°c and examined every 4-24 hours for clot formation. any degree of visible clotting was considered a positive result (tallent et al., 2001). additionally, suspected s. aureus cultures were inoculated onto purple agar base (pab) media supplemented with 1% maltose and incubated at 37°c for 24 hours. s. aureus isolates were expected to rapidly ferment east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 40-50 45 maltose, leading to the production of acidic metabolites that turn the medium and colonies yellow. ultimately, the isolates were considered positive for s. aureus if they exhibited catalase-positive and coagulase-positive results, combined with growth on msa and pab media with an associated yellow coloration of the media (quinn et al., 2002).. data analysis following data collection, records were entered into microsoft excel, coded appropriately, and then subjected to statistical analysis. mastitis prevalence was calculated as the proportion of cows diagnosed with mastitis (encompassing both clinical and subclinical forms) relative to the total number of examined lactating cows. to explore the association between putative risk factors and mastitis prevalence, odds ratios (or) were computed. on top of that, a logistic regression model was utilized with stata corp. (version 12.0) software to assess the independent contribution of each risk factor to the likelihood of mastitis. statistical significance for all analyses was set at a 95% confidence level, with a p-value < 0.05. results prevalence of mastitis this cross-sectional study investigated mastitis in 250 lactating cows. the results showed that 50.8% (l27/250) of the cows had some form of mastitis (either clinical or subclinical). among these, 4.8% (l2/250) exhibited clinical mastitis, while a larger proportion, 46% (ll5/250), had subclinical mastitis. when considering individual udder quarters, the overall mastitis prevalence was 27.4% (274/l000). clinical mastitis was identified in 2.9% (29/l000) of quarters, while subclinical mastitis affected 24.5% (245/l000) (table l). bacterial isolation bacteriological analysis was performed on the l27 milk samples obtained from cows diagnosed with mastitis to determine the presence of s. aureus. accordingly, s. aureus was isolated from 4l.6% (5/l2) of samples from cows with clinical mastitis and from 47.8% (55/ll5) of samples from cows with subclinical mastitis. the overall prevalence of s. aureus among all mastitis-positive samples was 47.2% (60/l27), as shown in table 2. . east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 40-50 46 table 2. prevalence of s. aureus in clinical and subclinical mastitis risk factors associated with mastitis multivariate lgistic regression analysis revealed that age of the cows, late lactation stage, and farm hygiene frequency were significantly assciated with mastitis. in contrast, milk yield, parity, and husbandry system were not identified as significant risk factors in this model (table 3). table 3. logistic regression analysis of potential risk factors for the occurrence of mastitis in the study area or: odds ratio, lit.: liter, no.: number discussion the present study found an overall mastitis prevalence of 50.8% at the cow level and 27.4% at the quarter level. these prevalence are consistent with those reported in earlier studies by hundera et al. (2005) and abera et al. (2010). in most developing cuntries, mastitis prevalence tends to be approximately 50% in risk factors categories no. of cows crude or (95% ci) adjusted or (95% ci) pvalue examined psitive (proportion) age (years) <3 4-5 >6 93 98 59 21 (22.6) 47 (47.9) 47 (79.7) 1 3.16(1.68, 5.92) 13.43(6.04, 29.85) 1 3.7 (1.63, 8.43) 17.61 (5.3, 58.44) 0.002 0.000 parity <2 >3 134 116 43 (32.1) 72 (62.1) 1 3.46 (2.06, 5.83) 1 1.29 (0.59, 2.79) 0.512 lactation stage (months) early mid late 85 89 76 27 (31.7) 43 (48.3) 45 (59.2) 1 2.01 (1.08, 3.72) 3.11 (1.63, 5.95) 1 1.81 (0.9, 3.62) 2.1 (1.0, 4.32) 0.094 0.049 milk yield per day (lit.) <10 11-15 >16 86 82 82 45 (52.3) 34 (41.5) 36 (43.9) 1 1.56 (0.84, 2.80) 1.41 (0.76, 2.58) 1 1.26 (0.61, 2.63) 1.39 (0.66, 2.94) 0.531 0.384 husbandry system intensive semi-intensive 233 27 102 (43.7) 13 (48.1) 1 1.10 (0.49, 2.45) 1 1.97 (0.68, 5.88) 0.213 frequency of farm cleaning per day > 4 times 3 2 36 130 84 10 (27.7) 53 (40.7) 52 (61.9) 1 2.36 (1.37, 4.15) 4.24 (1.80, 9.90) 1 2.94 (1.58, 5.81) 5.1 (1.85, 13.7) 0.002 0.002 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 40-50 47 cows and 25% in quarters. nevertheless, our findings are notably lower than those observed in several other ethiopian studies (abebe et al., 2016; zeryehun & abera, 2017; elem et al., 2017; tegegne et al., 2020), which documented cow-level prevalence ranging from 62.6% to 70%. conversely, the prevalence in this study was higher than earlier reports by workineh et al. (2002), mungube et al. (2004), and kerro and tareke (2003), which ranged from 38.2% to 40%. the prevalence difference across studies suggests that differences in husbandry practices and environmental factors play a critical role in mastitis incidence (radostits et al., 2007). the higher prevalence of sub-clinical mastitis (46%) than clinical mastitis (4.8%) encountered in the current study supports previus studies conducted in various parts of the country, which have consistently determined that sub-clinical mastitis is prevailing than clinical mastitis. in line with this, subclinical and clinical mastitis prevalence were 62.9% and 37.0% (kerro & tareke, 2003), 59.2% and 3.4% (abebe et al., 2016), 48.6% and 22.4% (mekbib et al., 2010), 36.7% and 10.0% (abera et al., 2010), and 27.86% and 11.45% (tassew et al., 2017) respectively. the consistently higher prevalence of subclinical mastitis in these studies, including ours, is likely due to its insidious nature and lack of overt symptoms which often delays detection and treatment (radostits et al., 2007). our study also found that mastitis prevalence was significantly higher during late lactation (59.2%), which is consistent with almaw et al. (2008), getahun et al. (2008), and abera et al. (2012). however, this contrasts with kerro and tareke (2003), who reported higher rates during early lactation. such discrepancies may stem from differences in cow age and parity (isae & kurtu, 2018). the present study also showed that older cows (>6 years) had a higher prevalence of mastitis (79.7%) than younger cows (<3 years) (22.6%), supporting the findings of kerro and tareke (2003) and busato et al. (2000). this increased risk in older cows has been attributed to anatomical changes, such as larger teats and weaker sphincter muscles, facilitating pathogen entry (radostits et al., 2007).the findings of the current study regarding the increased prevalence of mastitis with parity are consistent with previous reports by zeryehun et al. (2013), abunna et al. (2013), belayneh et al. (2014), and dabele et al. (2021). the likelihood of mastitis was 3 to 13 times higher in multiparous cows compared with primiparous cows. in line with this a study conducted by abebe et al. (2016) also reported odds of 24.8 for cows with four or more calvings. this association may be attributed to the fact that primiparous cows possess a more effective defense mechanism against mastitis compared to multiparous cows (erskine, 2001). the likelihood of infection increases over time in multiparous cows, leading to a prolonged duration of infection (radostits et al., 2007). a key finding of this study was that mastitis prevalence was significantly higher (61.9%) in cows housed in facilities cleaned twice daily, compared to those cleaned four or more times daily. this suggests that the frequency of cow house cleaning is an important factor in mastitis control, particularly of the environmental ones. notably, the study did not find a significant link between husbandry system (such as grazing, confinement) or a prior history of mastitis and current mastitis prevalence. these results should east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 40-50 48 be interpreted with consideration for the context of this particular study. the microbiological investigations identified s. aureus in 47.2% of mastitic cows, which corresponds with similar studies in holeta (mekibib et al., 2010) and addis ababa (legesse et al., 2015). however, some other studies have reported both lower (workineh et al., 2002; tesfaye et al., 2013; yohannis and molla, 2013; zeryehun et al., 2013) and higher (abebe et al., 2016; zenebe et al., 2014) prevalence of s. aureus. such variations among studies are likely due to husbandry practices and environmental differences. staphylococcus aureus, a mastitis causing contagious pathogen, is known for its ability to establish chronic, subclinical infections, as well as acute and clinical mastitis. consistent with tassew et al. (2017), our study found that s. aureus was more common in subclinical mastitis cases than clinical cases. this indicates that s. aureus is a key causative agent in these less visible infections, as they have a tendency to establish chronic long term infections and act as a source of transmission (radostits et al., 2007). the propensity of the bacteria to induce subclinical mastitis could be related to the numerous virulence factors including its capacity to produce biofilm, toxins, or various enzymes capable of damaging the udder tissue and concomitantly establish itself in the infected area (artursson et al., 2016). conclusion & recommendations mastitis remains a significant infectious disease in dairy cows, affecting the dairy industry significantly. in this study, subclinical mastitis was the most prevalent form, likely due to a greater focus on clinically visible forms by farm owners and animal health workers, which allows subclinical cases to go unnoticed. mastitis prevalence varied significantly with cow age, lactation stage, and farm hygiene practices. these findings highlight the need for routine screening and early intervention to detect and treat subclinical mastitis. furthermore, raising awareness about the public health risks and economic impacts associated with s. aureus is critical. acknowledgements the dairy farmers who gave permission to perform this study on their dairy farms are duely acknowledged. we also extend our appreciation to tesfaye tlesa and dr. mesele abera for technical support in the lab and provision of the cmt reagent, respectively. references abebe r., hatiy h., abera m., megersa b. and asmare k. 2016. bovine mastitis: prevalence, risk factors and isolation of staphylococcus aureus in dairy herds at hawassa milk shed, south ethiopia. bmc vet. res. 12(270): 2-11. abera m., demieb., aragaw k., regassa f. and regassa a. 2010. isolation and identification of staphylococcus aureus from bovine mastitic milk and their drug resistance patterns in adama town, ethiopia. j. vet.med. anim. health. 22(3): 29-34. abera m., habte t., aragaw k., asmare k. and sheferaw d. 2012.major causes of mastitis and associated risk factors in smallholder dairy farms in and around hawassa, southern ethiopia. trop. anim. health and prod. 44: 1175-1179. abunna f., fufa g., megersa b. and regassa a. 2013. bovine mastitis: prevalence, risk factors and bacterial isolation in small-holder dairy farms in addis ababa city, ethiopia. glob.veterinaria. 10(6): 647-652. almaw g., zerihun a. and asfaw y. 2008. bovine mastitis and its association with selected risk factors in smallholder dairy farms in and around bahir dar, ethiopia. trop. anim. health and prod. 40:427-432. east afr. j. biophys. comput. sci. 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(2023), vol. 4, issue. 1, 1-17 *corresponding author: email: kyayejue@gmail.com https://dx.doi.org/10.4314/eajbcs.v4i1.1s juliet kyayesimira1* and florence muheirwe2 1department of biological sciences, kyambogo university, p.o. box 1, kyambogo, kampala, uganda 2valley university of science and technology, p. o box 4, bushenyi, uganda. keywords: beef; handling practices; meat safety; consumer’s health; uganda abstract proper beef handling contributes to achieving sustainable develpment goals 3 (good health and well-being) and 12 (sustainable cnsumption and production patterns). this is because it ensures the safety of meat and consumers’ health. however, the meat sector is still underdeveloped in most african countries. in addition, there is limited research addressing meat safety challenges. in uganda particularly, in the recent past, there was whistle-blowing over contaminated beef on the market, indicating a loophole in food safety. despite this, studies focusing on beef handling practices have remained scanty. thus, this study aimed to examine beef handling practices at the abattoirs and butcher shops in uganda's central, western and eastern regions. a mixed-methods approach was employed to collect data through a survey, in-depth interviews and on-site observations. findings revealed that beef handling practices were poor at abattoirs and butcher shops and that most facilities for safety measures were lacking or inadequate. only 3% of the respondents had cold room storage facilities, and meat spoilage was relatively high (85.3%). appropriate knowledge of meat safety among abattoir and butcher operators was inadequate, contributing to low compliance with food safety guidelines. inappropriate handling practices and poor handling facilities may put consumers at a health risk. the study recommends that responsible authorities should ensure compliance mechanisms and sensitization initiatives are prioritized. introduction food safety ensures proper food handling, including beef and is crucial for ensuring the good health of consumers. proper beef handling refers particularly to the practices that prevent microbial contamination and spoilage of beef at all points along the meat value chain, from the abattoir to the dining table (niyonzima et al., 2013). it is noted that the unhygienic environment at both abattoirs and butcher shops (bafanda et al., 2017) leads to unsafe meat due to microbial contamination. poor handling of beef can result in the survival and multiplication of harmful microorganisms which grow on beef leading to beef spoilage (rouger et al., 2017). such meat is unsafe for consumption and may east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx beef handling practices at abattoirs and butcher shops in uganda: implications for meat safety and health of consumers research article mailto:kyayejue@gmail.com https://dx.doi.org/10.4314/eajbcs.v4i1.1s east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 1-17 2 lead to food poisoning (haileselassie et al., 2013). this may contravene sustainable development goal (sdg) number three, which focuses on good health and well-being of people. additionally, suppose meat spoilage is high at butcher shops and abattoirs, fulfilment of the sdg 12 target of reduction of food waste at the retail and consumer levels to reduce food losses along production and supply chains may not be achieved (undp, 2015). thus, appropriate handling of beef during and after slaughter is significant for fulfilling the sdgs. poor food handling has been identified as one of the contributing factors to various ailments. for instance, poor food handling contributes to foodborne disease outbreaks (gorman et al., 2002; gilbert et al., 2007; peh, 2008). notably, microbial pathogens are responsible for most of the food borne disease burden in developing countries and cause 20%–40% of intestinal disorders (grace, 2015). food-borne illnesses manifest in ill health such as stomach upsets, diarrhoea, fever, vomiting, abdominal cramps, and dehydration to more severe illness and even death (scallan et al., 2011; thomas et al., 2013; tegegne and phyo, 2017; yenealem et al., 2020). in pregnant women, foodborne illness may result in complications such as miscarriages, premature births, maternal and neonatal sepsis, and infant mortality (tam et al., 2010). in this respect, promoting safe handling in the meat value chain contributes to food safety and is significant for the safe consumption of meat. meat safety requirements and standards in most poor countries are below the desired status. for instance, at the abattoirs, meat may be dressed on the floor (fearon et al., 2014), and there are no basic facilities like stunning, bleeding, evisceration, and cooling rooms (haileselassie et al., 2013). after slaughter, meat is transported in open trucks and poorly packaged without regard to safety measures (fearon et al., 2014) when delivered to butcher shops. at most butcher shops, hand washing and water storage facilities may be lacking, inadequate, or inappropriate (bogere and baluka, 2014). in some premises, the meat is exposed to heat from the sun, which attracts dust and flies from the surrounding environment (kyayesimira et al., 2019). worse still, most people engaged in the meat production and processing value chain may not even be trained in hygienic procedures or meat technology (akabanda et al., 2017). therefore, such handlers may not implement measures they are unaware of or may not comprehend the significance of upholding the required standards. a considerable amount of literature has been published on the meat sector. these include; studies on microbiological quality and meat safety (koutsoumanis and taoukis, 2005; niyonzima et al., 2013; obeng et al., 2013; kebede et al., 2014; santos et al., 2017) and meat handling practices (birhanu et al., 2017; pal et al., 2018). these studies above have been conducted in different contexts and are content specific. for instance, santo and colleagues’ study on butcher shops in portugal cannot reflect the situation in developing countries because the food safety standards vary significantly. although studies by; kebede and colleagues in ethiopia, niyonzima in kigali and obeng in ghana may represent the sub-saharan context, they do not holistically look at the practices in the meat value chain from slaughter houses to shops. hence, studies on meat handling practices in sub-saharan africa remain scanty. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 1-17 3 other scholars have studied meat hygiene and associated health hazards to consumers ( chepkemoi et al., 2015; bafanda et al., 2017; wambui et al., 2017) and knowledge and practices of meat safety (sulleyman et al., 2018). bafanda and colleagues (2017) focus on awareness among consumers, which may not change if meat handlers, who are the culprits, do not improve handling standards. chepkemoi and colleagues (2015) focus on the sanitation of butcheries, while wambui and colleagues focus on good hygiene in slaughterhouses. the two studies do not address the contamination that may occur both at slaughterhouses and butcher shops, putting consumers’ health at risk. in uganda, studies on meat safety have also been conducted. musoke et al (2016) examined meat inspection at slaughter to detect meat that may be unfit for home consumption for the prevention of zoonotic diseases. a study on the contamination of ready-to-eat meat in highway markets was also conducted (bagumire and karumuna, 2017). compliance with postharvest handling practices of beef along the meat value chain has been studied (kyayesimira et al., 2019). however, these studies do not focus on beef handling practices at abattoirs and butcher shops and meat safety for consumers' health, which is the focus of the present study. in recent years, there has been an increasing amount of literature on meat, but few studies have been conducted in uganda emphasising beef handling. yet, in the year 2018, uganda woke up to the news that meat in butcher shops had been contaminated with a chemical known as formaldehyde, commonly found in hospitals to preserve dead bodies (ssali, 2018). when sprayed over the meat, it was revealed that it keeps away the flies. such premises attract customers who are lured into thinking that the butcher shop has high standards of hygienic conditions (yiga, 2018). such incidents revealed consumers' vulnerability to unsafe meat and meat products. meat may appear appetizing or luring and may not be fit for human consumption. this may be due to contamination at either slaughterhouse before it reaches butcher shops. improper meat handling practices contribute to making it unsafe for consumption. at any point of contamination, if such meat is consumed, it might contribute to health disorders of consumers. therefore, the present study explored beef handling practices in the abattoirs and butcher shops in uganda and implications for meat safety and consumers' health. materials and methods study sites the research was conducted in the districts of mbarara, kampala, and mbale, situated in the western, central, and eastern regions of uganda, respectively. the three (3) districts were selected because they are the biggest destinations for cattle market, with kampala district housing the biggest abattoir in the country, which slaughters 500-700 cattle daily (thorell, 2014). study design and data collection a cross-sectional study design was employed. a survey, in-depth interviews, and observations were conducted using a mixed methods approach. the study units were slaughterhouses and abattoirs and butcher shops. a total of 460 respondents, comprising 105 respondents from east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 1-17 4 abattoirs and 355 from butcher shops, were selected from the three districts using simple random sampling. at each district, the department in charge of production provided the number of abattoirs and butcher shops. respondents from abattoir and butcher shops were selected using the formula of taro yamane (1967), as indicated below where n=the sample size, population size (30156 for butcher shops and 142 abattoirs), e= the acceptable sampling error at a 95% confidence interval. this formula was chosen because proponents of this formula recommend that when one is studying a finite population, it is more appropriate (adam, 2020; singh et al, 2014). in this study, the finite population was respondents from abattoirs and butcher shops from the 3 study districts. respondents included abattoir operators, butchery owners, butchery operators, and butchers. butchers are directly involved in slaughtering, transporting, and selling meat. they were selected to get views on the handling practices regarding the quality of meat, hygiene and safety measures and standards. key informants (30) were purposively selected and distributed equally in all study districts. they included district veterinary officers (dvos), meat inspectors, uganda national bureau of standards (unbs) staff and chairpersons of meat associations of butcher shops and abattoirs. these were interviewed to get perspectives on meat safety and compliance standards. the data was collected between june, 2018 to january, 2019. data collection methods an interview guide enabled information collection on food safety guidelines and standards awareness. it also facilitated the collection of information on whether the meat processing industry and value chain actors understood the consequences of their actions on the health of families and the community. participants were interviewed at workplaces and given priority to serve clients. the interviews were conducted in the mornings, afternoons, and evenings depending on customer flow at the butcher shops. the research team did not want to disrupt the attendants from serving customers but focused on gaining the respondents' undivided attention for more information. at the abattoir, interviews were conducted in the mornings when slaughtering was usually done. the research team wanted to observe the processes and practices of meat handling as it was slaughtered and distributed to customers. the time frame of the interview schedule varied from one place to another but took more than one hour to two on average. the time taken to conduct interviews was long because of the disruptions when clients showed up, and the researcher would pause the session to enable the respondent to attend to the client first. interviews were conducted in the predominant local languages of the respective study areas which were runyankore in mbarara, lumasaba in mbale and luganda in kampala, to allow the respondents to express themselves freely. observation was also employed as a critical tool to establish the status of the butcher shops and abattoirs. in this exercise, the sense of smell and east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 1-17 5 vision were vital in establishing the hygiene of the business units operating as butcher shops and abattoirs. the researchers observed how customers were served the meat they had purchased. the processes of cutting meat, measuring and packaging for customers, chopping boards, the equipment used, the storage facilities, and the hygiene of the surroundings were observed. some relevant documents were also reviewed to understand and comprehend the meat handling practices and their implication for consumers. reviewed documents included the sustainable development goals, the unbs standards, the national environment management authority (nema) regulations and other policy documents, as well as, regulatory guidelines. data analysis all quantitative data, mainly generated from the questionnaire, were processed and analyzed using the statistical package for social sciences (spss) version 20 (ibm corp. armonk, ny: released 2011) and sigma plot version 14. frequencies and percentages were computed for meaningful interpretation of results presented in the form of tables in the results and discussion section. qualitative data were analyzed using the thematic approach, where common themes were categorized, coded, and interpreted for meaning. these were used to complement data from in-depth interviews and document reviews. research ethical considerations before data collection, approval was obtained from the national council for science and technology in uganda to implement this research under the reload research project uganda (reload/a0401unscst2012). at the university, approval was acquired from the mbarara university of science and technology research ethics cmmittee (must-rec). during data collection, participants were briefed about the aim of the research to seek consent and voluntary participation. this was done verbally, and a request to take pictures was made. pictures taken and provided in this paper were taken from premises where respondents had consented verbally, and for those who were not willing, their concerns were respected. the pictures have been presented in blurred form to protect the participants’ identities. results and discussion socio-demographic characteristics of respondents this study was interested in the levels of education and gender of respondents. the study presumed that education should influence better meat handling practices. previous studies reported high education level was related to safe food handling (karabudak et al., 2008; jianu and goleţ, 2014). findings from the study (table 1) revealed that most beef handlers at the abattoir and butcher shops had attained basic education. for instance, most abattoir operators had primary education (48.6%), while most butcher shop operators (46.2%) had acquired secondary education. few of the respondents had no formal education. as this study reveals, there seems to be a basic literacy level among the meat industry operators. similarly, in malaysia, the majority of food handlers had primary and secondary level education (rosnani et al., 2014). contrary, in ogun state of nigeria, it was found that the majority of the handlers had low literacy levels of up to primary east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 1-17 6 education (fasae and bakare, 2016). these revelations suggest that the level of education of operators in the meat industry is low and could contribute to the unsafe handling of meat. gender was thought pertinent to this study because men and women may have different ways of conduct. this may determine varying meat handling practices. this study revealed that men dominated the meat sector, as indicated in table 1. this could be attributed to the masculine nature of the work at the abattoirs and butcher shops. the findings of this study are similar to those of other scholars (abdeirazig et al., 2017; kikulwe et al., 2018) who found males dominating several food value chain nodes compared to their female counterparts. notably, in nigeria, 100% of beef handlers were male (fasae and bakare, 2016). given the findings, men seem to dominate in sectors where activities may be strenuous. table1: number of respondents by education and gender variable abattoir operators butcher shops operators no frmal education 7 (6.7 %) 5 (1.4%) primary education 51 (48.6%) 154 (43.4%) secndary educatin 35 (33.3%) 164 (46.2%) tertiary educatin 7 (6.7%) 16 (4.5%) graduate 5 (4.8%) 16 (4.5%) male 103 (98.1%) 352 (99.2%) female 2 (1.9%) 3 (0.8%) meat handling practices at slaughterhouses and butcher shops results from observations at abattoirs (slaughterhouses) showed that tools and carcasses were being handled unhygienically during and after the slaughter process, as shown in plate 1. plate 1: unhygienic slaughter process: on floor slaughter (left) and unhygienic meat handling practices at a slaughterhouse (right) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 1-17 7 it was noted that workers wore dirty and torn protective wear, kept knives in gumboots, and carried meat over clothes. also, flaying and dressing were done on the dirty floor. most slaughterhouses did not separate stunning rooms from other processes. the slaughterhouses in all the study districts had substandard facilities and lacked design requirements per the standard for the design and construction of slaughter areas (unbs, 2017). this seems not to have improved since an earlier study in uganda also confirmed similar flaying practices and dressing on the floor (bogere and baluka, 2014). a similar study in northern nigeria reported that slaughterhouses lacked basic structures leading to unsafe meat (bello et al., 2015). in an interview with one of the officials from the meat inspection unit, it was further explained that, particularly in mbarara and mbale, the slaughterhouses were operating below the required standards, unlike in kampala, where a few were complying. the official attributed this to the fact that the rate of compliance to standards in kampala, a city, is higher than in urban areas in other regions. this study noted that in mbale and mbarara, there was one meat inspector per district, unlike in kampala. this could probably explain the revelation from one of the key informants that there is slightly fair compliance to better meat handling practices in the city. however, from the observation in this study, there was no clear distinction in terms of compliance with proper meat handling in all the study areas. this seems to concur with the ministry of agriculture animal industry and fisheries (maaif) report, which indicated that uganda lacks better slaughter facilities that respect health, food safety, and environmental standards (maaif, 2020). in line with the current findings, a study in abiia and the immo states of nigeria revealed low compliance of meat handlers to best practices (iro et al., 2017). in kenya, slaughterhouse meat handlers were not washing their hands, and equipment handling practices were inadequate (wambui et al., 2017). these revelations suggest that uganda is not the only country that does not meet the desired handling practices at slaughterhouses. regarding butchery structures (meat shops), findings revealed that most (96.6%) of beef sales in the study were made from kiosks with no cold rooms. other beef sales were made in open structures, under the tree and a few butchers (3%) owned kiosks with cold rooms, as shown in plate 2. . plate 2: the meat shops common in the study areas showing meat displayed along the dusty roads most of the butchery establishments (96.6%) lacked cooling facilities. it was observed that meat is displayed for sale, exposing it to dust and flies. when one of the respondents was probed about why meat was being displayed in the open, he had this to say, east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 1-17 8 ‘…you may not attract potential clients if you do not display your meat. that is what everyone selling meat does in this area. when customers come, they move around as they check out the best and attractive meat before deciding to buy. if you do not display, nobody will know that you are selling meat, and they might think that your stock is finished….’ this study indicates that meat retailers have been accustomed to displaying meat, and customers are used to buying meat on display. this could be attributed to the ignorance of both parties on proper meat handling and food safety standards. it is acknowledged that informal butcheries are widespread in uganda (agriterra, 2012). in this study, it was also observed that most butcheries lacked fly-proof windows or doors to prevent the entry of insects, and none had running water. a similar study in kampala, uganda, found that most butcheries lacked a standard fly screen and fly-proof window (mirembe et al., 2015). this means the flies can transmit pathogens/microbes from one point of meat sale to another, leading to unhygienic situations. the close proximity of several butcheries and their practice of sharing weighing scales, stones, and cutting tools created a high risk of cross-contamination. if one piece of shared equipment became contaminated, it could potentially spread to all the participating businesses. storage facilities and transportation of beef according to hygiene requirements for a butchery, a chilly environment for storage is a requirement for optimum meat safety. it was, therefore, significant for this study to examine storage facilities in the study area. study findings revealed that slaughterhouses in kampala had chillers but were lacking in the slaughterhouses in mbarara and mbale. meat shops lacked cold storage facilities; daily meat for sale was stocked, but if all was not sold, it was left hanging in the facility. butcheries lacked cold storage rooms because there was no power supply coupled with limited innovation on solar usage in refrigeration. in one of the discussions with the veterinary personnel, it was revealed that butcher operators in mbarara and mbale were reluctant to use cold storage rooms because the temperatures were not as high as in kampala. this was also on the assumption that in places with cool temperatures, the spoilage rate and level of contamination may be below. in contrast, the contamination rates and levels are higher in the wet and rainy seasons (bagumire and karumuna, 2017). another reason that was provided for not refrigerating meat was that customers consider refrigerated meat not to be fresh, as one respondent during the interviews noted: ‘you see most customers when they come, especially in the morning, they want to see the meat dripping with blood, and they even caution you that…please do not give me any meat that stayed overnight…some even check to confirm it is not chilled.’ for that matter, i do not store meat in the chillers. in relation to this study, agriterra (2012) reported that enormous roadside small-scaled butcheries in kampala lacked refrigeration. the butchers preferred to buy meat in relatively small quantities that could be sold in one day. agriterra further reveals that the butchery structures were not appropriate according to the ugandan standard on hygienic requirements of butcheries (unbs, 2007). in kenya, chepkemoi et al. (2015) noted that butcher shops in nairobi and isiolo counties stored meat by hanging it in east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 1-17 9 open spaces. similarly, a study in south sudan noted that many meat-selling structures were open shelters and kiosks that left meat hanging in the open air (aburi, 2012). these revelations portray poor storage conditions, which can accelerate microbial growth and hence quicken meat contamination. transportation is another aspect that compromises the hygiene of meat and hence its safety. the conditions of transporting meat should provide adequate protection from contamination (rani et al., 2017). this study aimed to understand how meat was transported, especially from slaughterhouses to butcheries. the results of the present study indicated that the majority (54%) of the carcass (beef) was transported by motorcycles, followed by bicycles (25%), and a few (1%) used wheel barrows or shoulder-to-shoulder logs. motorcycles were not only popular in uganda for transporting meat but also in ghana, where the majority (93%) of the butcher men transport beef on bicycles, motorbikes, and motorized tricycles, popularly known as motor kings under very unhygienic conditions (fearon et al., 2014). this study also observed that sometimes meat was carried in sacs or polythene bags and would drip blood, attracting dust and flies along the way. this is unlike kenya, where meat is mostly transported in metallic containers (chepkemoi et al., 2015). in this study, motorcycles were also loaded with wooden boxes where beef is placed and then covered during transportation, but some were left open. in kenya, chepkemoi et al. (2015) noted that metallic boxes in which meat is transported are mainly closed. covering meat is important because in cases where the boxes are left open, and meat is not wrapped, it may expose it to dust, flies, and other sorts of contamination. there are standards for transporting and handling meat at both the global and local levels. for instance, the code of hygienic practice for meat requires that it is handled, stored, and transported in a manner that will protect it from contamination and deterioration (cac/rcp, 2005). the modes of transport of meat should maintain proper refrigeration temperatures at critical points such as loading and off-loading (richardson et al., 2009). however, refrigeration is unavailable in some abattoirs and during transportation in developing countries (aburi, 2012; agriterra, 2012; chepkemoi et al., 2015; rani et al., 2017). poor modes of transport like shoulder-toshoulder logs provide a conducive environment for contamination with and growth of some pathogenic and spoilage micro-organisms that would put consumers at risk. occurrences of beef spoilage at butcher shops beef spoilage could be common in facilities with poor storage and handling practices. study results indicate that beef spoilage was common in butcheries. the kind of beef spoilage occurring at the slaughter included; bad odor, bruised meat, change of color, and rotting, among others, due to beef overstay at the point of sale. over 85.3% of butchery operators reported beef spoilage, as in table 2. meat handling practices at slaughterhouses and butcher shops results from observations at abattoirs (slaughterhouses) showed that tools and carcasses were being handled unhygienically during and after the slaughter process, as shown in plate 1. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 1-17 10 table 2: frequency of beef spoilage occurrence at butcher shops mbarara kampala mbale average % occurrence of beef spoilage yes 102(85.2%) 100 (75.5%) 97 (95.1%) 85.3 no 18 (14.8%) 33 (24.5%) 5(4.9%) 14.7 % occurrence of beef spoilage daily 37 (27.9%) 41(34.4%) 37 (36.3%) 32.8 weekly 52 (39.3%) 28 (22.9%) 33 (32.4%) 31.5 biweekly 4 (3.3%) 1 (0.5%) 2 (2.0%) 1.9 monthly 18 (13.2%) 18 (15.1%) 17 (16.7%) 15.0 occasionally 2 (1.6%) 3 (2.1%) 8 (7.8%) 3.9 not applicable 20 (14.8%) 30 (25%) 5 (4.9%) 14.9 type of spoilage incurred (%) bad odor 20 (14.8%) 1 (1.0%) 13(12.7%) 9.5 meat changes color 4 (3.4%) 8 (6.7%) 7 (6.9%) 5.6 rots after some days 22 (16.4%) 9 (7.8%) 12 (11.8%) 12.0 bruised meat 2 (1.6%) 3 (2.1%) 3 (2.9%) 2.2 drip loss 20 (14.8%) 19 (15.6%) 14 (13.7%) 14.7 beef wastes 48 (36.1%) 51 (42.7%) 48 (47.1%) 41.9 not applicable 17 (13.1%) 29 (24.0%) 5 (4.9%) 14.0 the fate of spoilt beef given to dog owners for free 22 (16.4%) 10 (8.3%) 39 (38.2%) 21.0 thrown away 89 (67.2%) 62 (51.6%) 9 (8.8%) 42.5 sells it to clients for dogs 20 (14.8%) 48 (40.1%) 33 (32.4%) 29.1 takes it home for consumption 2 (1.6%) 0 (0%) 21 (20.6%) 7.4 daily, the average beef spoilage was reported at 32.8% in the study areas. the respondents at the butcher shops indicated that, at times, beef that remains at the end of the day is left hanging in the retail premises because of a limited refrigeration system. similarly, butcher shops in nairobi and isiolo counties, kenya, also store meat by hanging it in open spaces (chepkemoi et al., 2015). in this study, meat sales are made near dusty roadsides, and the meat is displayed for customers by hanging it on the veranda (close to the road). this exposes meat to contamination, accelerating the rate at which meat may get spoilt. a study in uganda found that enormous roadside small-scaled butcheries in kampala lacked refrigeration (agriterra, 2012) and could accelerate beef spoilage. a previous pilot study in uganda revealed that any balance of meat was either stored in the freezer or left hanging in the butchery. in contrast, the rest of the butcheries sold off the balance cheaply to avoid carry-over to another day (kyayesimira et al., 2018). the beef left hanging in the butchery overnight is susceptible to microbial growth that quickens spoilage. this study revealed that meat not sold off is carried on to the next day, mixed with fresh stock and sold to unsuspecting customers. one of the attendants of a butcher shop (key informant) confirmed this practice by saying: ‘normally the meat that stays is very little and so to avoid making losses when a customer comes, we cut fresh meat and as we measure the east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 1-17 11 amount requested by the customer, we add on the meat of the previous day’. this practice is absurd since it lures consumers into thinking that the shops are selling fresh meat but instead, the meat is mixed with the previous stock, which may be spoilt. mixing fresh stock with the previous one (unrefrigerated) may also contribute to the rate at which all stock may get spoilt. this study observed that meat tending to spoilage attracted many fly populations. it was also revealed that when the environment of the meat-selling premises is not hygienic, it acts as fly breeding grounds that swim to butcher shops worsening the hygienic conditions of the premises and the meat. this situation could lead to a disease outbreak. as noted, in thailand, there was a linkage between fly populations associated with disease outbreaks and cases of food-associated pathogens, for instance, vibrio fluvialis, e. coli, vibrio cholera and campylobacter spp (graczyk et al., 2001). it was in the interest of this study to find out where the spoilt beef was taken. findings revealed that the fate of beef after spoilage was to throw it away, as was reported by 42.5% of respondents, 29.1% reported that the spoilt meat was sold to clients, while 7.4% mentioned that they took it home for consumption. when probed about it, the respondents claimed that despite the unpleasant odour, it may not pose a danger to consumers’ health if it is well cooked. the respondent's perspectives seem to concur with bogere and baluka (2014),who also noted that microorganisms might be destroyed if cooking is effectively conducted. however, in some households where raw meat is consumed, it could pose a health risk. other respondents explained that spoilt meat is roasted first to eliminate the unpleasant odour, a delicacy in some households. these revelations indicate that operators lack adequate knowledge regarding food safety and its health implications. meat inspection at slaughter and butcher shops meat inspection is crucial in the meat industry because it ensures meat safety and hygiene. during the study, it was observed that there were no meat inspections taking place at the slaughter slabs. instead, the inspection was observed being conducted at the slaughterhouses. this may not conform to effective monitoring principles, where every stage in the slaughtering process is critical for meat safety. abattoir operators informed the study that meat inspectors are supposed to inspect the meat that is slaughtered before it is distributed to clients. at butcher shops, respondents revealed that the team from the district does inspections. however, there seems to be concerns that meat inspection in uganda has been inadequate. for instance, bogere and baluka (2014) noted that the inspection of abattoirs and butcher shops by both the veterinary and public health inspectors had been insufficient. thus, the meat safety and hygiene standards have deteriorated (bogere and baluka, 2014). it should be noted that butcher’s shops act as links between the inspected and approved safe meat for consumption, and therefore, inspection in the whole meat value chain is crucial for ensuring meat safety (waldman et al., 2020). at the slaughterhouses, it is a requirement to conduct ante mortem inspections. this study established that kampala district had higher eajbcs__volume_4_issue_1_article 1_ juliet and muheirwe_ beef handling practices at abattoirs and butcher shops in uganda.pdf (p.7-23) introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction microsoft word tiguaded_ theoretical model predictions for production of medically used radionuclides _doi east afr. j. biophys. comput. sci. (2024), vol. 5, issue. 1, 1-12 theoretical model predictions for production of medically used radionuclides on alpha induced with cobalt-59 at energies of 25 172 mev department of applied physics, hawassa university, p.o.box 05, hawassa, ethiopia keywords: complet code; excitation function; radionuclide production; reaction cross section; talys-1.95 code abstract this study used the theoretical nuclear model codes complet and talys-1.95 to make theoretical predictions of the medically important production cross-sections for chromium-51, manganese-54, iron-59, cobalt-59 and cobalt-60 radionuclides produced in the interaction of alphaprojectile with cobalt-59 target ≈ 25 – 172 mev alphaenergies. the results were compared with the measured values in the exfor data library. pearson's correlation coefficient indicates a strong and positive correlation between the predicted and the previously measured medically important production cross-sections for chromium-51, manganese-54, iron-59, cobalt-59, and cobalt-60 radionuclides. further, the results showed that except for chromium-51, the complet code predicts more successful outcomes than the talys-1.95. introduction nuclear reaction cross-section data are very important to the field of medical radiobiology in both diagnostic imaging and targeted therapy (kebede, 2021), which is crucial for the optimized production of radionuclides. in nuclear medicine, radionuclides are used for various useful applications, such as diagnosis, therapy, prevention of many serious ailments, and research to evaluate metabolic, physiologic, and pathologic conditions of the human body (aydin et al., 2007). the successful production and usage of these radionuclides extends to oncology, cardiology, and even psychiatry through imaging procedures where information about the function of every major organ and tissue of the human body can be generated. many radionuclides used in nuclear medicine are produced in cyclotrons, accelerators, or nuclear reactors, and production is an important and constantly evolving issue. in addition to this, different radionuclides play significant roles in technological applications of importance to our daily lives and scientific research (aydin et al., 2007; kilinç et al.,2016). journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs east african journal of biophysical and computational sciences *corresponding author: email: a_fessahatsion@yahoo.com +251911567435 https://dx.doi.org/10.4314/eajbcs.v5i1.1s y. tiguaded, f. k. amanuel* research article east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 1-12 2 the positron emission tomography (pet) imaging technique is widely used for planning, early diagnosis of cancer, and evaluation of the treatment response in patients with cancer. this imaging technique is also used to study diseases of the heart, brain, thyroid, etc. (noori et al., 2017) for example, cobalt-57(t1/2 =272 d) is used as a marker to estimate organ size and for in vitro diagnostic kits. similarly, chromium-51 radionuclide (t1/2=28 d) is used to label red blood cells and quantify gastro-intestinal protein loss (aydin et al., 2007; kilinç et al., 2016). production cross sections for charged particles, especially nuclear reactions on metals that are induced by alpha, are important in medical radioisotope production (mohamed, 2006; demir et al., 2017). accordingly, reasonable comparative theoretical reaction model studies with an experiment using light-charged projectiles (proton, deuteron, and alpha) are beneficial (qaim et al., 2016; tárkányi et al., 2019; amanuel, 2023) because of the nonavailability of experimental cross-section data for the production of medical radionuclides, particularly in alpha-induced reactions, which are limited and still need further investigations. to optimize the production routes, charged particle-induced cross-sections are desired. to optimize the radioisotope produced, a full knowledge of the excitation function is necessary, which helps maximize the yield of the desired product and minimize the radioactive impurities (qaim et al., 2002). in radionuclide production, accurate reaction cross-section data are required for wellcontrolled and maximized production routes (mohamed, 2006; qaim, 2010). nuclear reaction model-based computer codes can be essential in predicting production cross-sections, particularly for radionuclides whose experimental data are either unavailable or have significant discrepancies. in addition, theoretical model predictions have played a crucial role in creating optimized reference cross-section data, particularly in producing medically useful radionuclides (koning et al., 2013) that were calculated using the monte carlo nuclear reaction simulation codes talys 1.95 and complete. despite all efforts, one of the crucial aspects of the reaction mechanisms study is finding optimized production routes for radionuclides, particularly for medically used radionuclides. moreover, it is evident that the non-availability of experimental cross-section data for producing medically useful radionuclides, particularly in alpha-induced reaction, are very limited and need further investigation. therefore, the present work focuses on finding optimized production routes for medically useful radionuclides produced in the reaction of αprojectile with 59co-target, more specifically, to evaluate the nuclear data for the production of chromium-51, manganese-54, iron-59, cobalt59, and cobalt-60 on alpha-induced cobalt-59 at alpha energy of positron-emitting radionuclides. materials and methods several theoretical nuclear reaction model-based computer codes have been used to predict radionuclide production cross-sections (koning et al., 2013; amanuel, 2023). in this work, predictions of production cross sections for 51 cr, 54mn, 59fe, and 57,60co radionuclides produced in the interaction of alpha-projectile with cobalt-59 target via (a, x) channel were carried out using the computer codes talyseast afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 1-12 3 1.95 and complete. the results were compared with the experimental data (michel et al., 1980). these codes were prefered because they have been successful and widely used for predicting production cross-sections and evaluating reaction data (amanuel, 2023). the present work also used the default values of the level density nuclear model talys-1.95 computer codes. talys-1.95 code talys-1.95 code is an advanced version of the talys code family with additional features. talys was first developed in 1998, aiming to consolidate the understanding of nuclear reactions into a single software tool. this program integrates various models—including pre-equilibrium, direct, optical, statistical, and fission nuclear reaction models—enabling predictions across all open reaction channels within one calculation framework (qaim et al., 2016). the monte carlo reaction code simulates various types of nuclear reactions, operating on a linux system and written in fortran. a significant advantage of employing a monte carlo method for nuclear data evaluation is its ability to extract a series of correlations from prior results. consequently, the code was developed with the objective of delivering a comprehensive and accurate simulation of nuclear reactions involving neutrons, photons, protons, deuterons, tritons, 3he, and alpha particles within the energy range of 1 kev to 200 mev, with a few exceptions. the data generated or used by the code developed for the monte carlo method is derived from a reference input parameter library, combining reliable nuclear models with a focus on resilience and user-friendliness (koning et al., 2013). the theory of excitation functions for the generation of medical radioisotopes are obtained with alpha-induced reactions (a,x) for some radioisotopes used in clinical medicine that are relevant for the development of better nuclear reaction theory and for several medical applications were computed by using talys 1.95 code. in general, the reaction cross section for entrance channel α and exit channel β of this code can be expressed, using hauser-feshback (hauser-feshback, 1952) formalism as follows: σαβ = π k2 ∑ (2j+1) (2iα+1)(2iα+1)j ∑ tℓs,ℓ (α) ∑ tℓ , s,,ℓ , (β) ∑ ∑ tℓs,ℓ (α)α (1) where s is the channel spin, tℓrepresents the transmission coefficients, and l is the orbital angular momentum. the hauser-feshback formula is simplest for the energy-average angle integrated cross-section of statistical reactions (reaction cross-section leading to a single final state). complete code computer code complete is a revised and improved version of the alice code family with additional physics, corrections, and competencies and has been used to predict production cross-sections (asres et al., 2018). this code has successfully predicted several nuclear data sets, particularly for the production of radionuclides used in nuclear medicine medical (yiğit and tel, 2013; asres et al., 2019). this code utilizes the weisskopf-ewing (weisskopf and ewing, 1940) formulation for compound nucleus (cn) emission, along with blann’s hybrid and geometry-dependent hybrid models for particle emission (pe) (blann and east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 1-12 4 vonach, 1983). in the complete code, level densities of residual nuclei play a crucial role in deciding the shapes and absolute values of excitation functions (akkoyun et al., 2015). this code uses the weisskopf-ewing formulation to predict reaction cross-sections as follows: σ dε = σ (α) ( ) ( ) ( ) ∑ ∫ ( ) ( ) ( ) (2) where u is the reduced mass of the ejectile α, and σ (α) is the cross-section for the production of the cn. comparison between experimental and theoretical results as shown in figures 1–5, the theoretical and experimental reaction cross-sections are represented in relation to the projectile energies. pearson's correlation coefficient quantifies the level of mutual statistical dependence between two variables (baak et al., 2020). typically, their values range from -1 to +1 or 0 to +1, where 0 means no statistical association, +1 means the strongest possible association, and −1 means the strongest negative relation. in general, the data of this study have been analyzed after the theoretical data have been generated using the computer codes talys1.95 and complete. the theoretical and experimental total cross-section results are compared using pearson's correlation coefficient. correlation is a measure of association between two variables. the mathematical description is given by tárkányi et al. (2019). r= ∑ (xti −<xt>)(xei −<xe>)n i=1 (n−1)(sxt)(sxe) (3) where ; < x >= ∑ x (4) s = ∑ (x −< x >) (5) < x >= ∑ x (6) s = ∑ (x −< x >) (7) where r is the correlation coefficient and unit less, 〈xt〉 and 〈xe〉 are the mean theoretical and experimental reaction cross-sections, respectively, x and x are the theoretical and experimental total cross-sections of the i value, respectively, whereas n is the number of the theoretical and experimental data, and sxe and sxt are the standard deviations of the experimental and theoretical total crosssections, respectively. if 0 ≤ r ≤ 0.3, the correlation is weak and positive, 0.3≤r ≤ 0.7 describes a moderate correlation, and 0.7 ≤ r ≤1, the correlation is strong (baak et al., 2020). results and discussion the current work investigated the excitation functions of medically important chromium-51, mangenes-54, iron-59, cobalt-59, and cobalt60 radionuclides produced in the interaction of alpha-projectile with cobalt-59 target at 25–172 mev alpha-energies. in addition, the experimentally measured excitation functions available in the literature (michel et al., 1980) were compared using the nuclear reactionmodel codes talys-1.95 and complet. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 1-12 5 in complete code, the level density parameter a, which predominantly influence the equilibrium state components of a cross-section, is computed from the expression: 𝑎 = (8) where a is the nucleon number of a compound system, and k is an adjustable constant, which may be varied to match the experimental data. for the present system, a representative 59co (α, x) 60co reaction, the value of k was varied (k = values of 8, 10, and 12 were used) to match the experimental data. a value of k = 10 in general reproduced satisfactorily experimentally measured efs for cobalt-60 residue. this value is consistently used for other residues populated in the interaction of the alpha-projectile with the target cobalt-59. for the same representative cobelt-60 residue, the initial exciton numbers no = 4 (2,2,0), 5 (2,2,1) were varied, and it was found that a value of no = 4 (2,2,0) better reproduced the measured excitation function (michel and brinkmann, 1980). for complete code prediction, k = 10 and no = 4 are consistently used for all residues populated in the interaction of the alpha-projectile with the target cobalt-59. production of chromium-51 radionuclide figure 1 illustrates the excitation functions for the chromium-51 radionuclide, which were predicted theoretically and measured experimentally, as produced through the (α, x) channel during the interaction of the alpha projectile with the cobalt-59 target. by using the talys-1.95 code, predicted cross-section values, except at alpha energies of 90–120 mev, are in very good agreement with the measurements of michel and brinkmann (1980). it may further be seen that complete code predicted cross-section values that were generally in satisfactory agreement with the measured values of michel and brinkmann (1980). table 1 reveals that the pearson's correlation coefficient values for the cross-section predictions from talys-1.95 and the complete code indicate a strong positive correlation between the theoretically predicted and experimentally measured production crosssections (michel and brinkmann, 1980). east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 1-12 6 figure 1. the experimentally measured and theoretically predicted excitation functions for medically used crominum-51. production of manganese-54 radionuclide the experimentally quantified production crosssections for manganese-54 radionuclide from the existing literature are compared with the theoretical predictions obtained using the complet and talys-1.95 codes. figure 2 shows the quantified excitation functions along with theoretical predictions for manganese-54 radionuclide produced through the (𝛼, x) channel in the interaction of alpha-projectile with a cobalt-59 target at 25 mev–172 mev. using complete code, predicted crosssection values except for 60 mev–90 mev are in very good agreement with the cross-section values measured by michel and brinkmann (1980). figure 2 shows that the predicted crosssection values using the talys-1.95 code generally minimize the measured values of michel and brinkmann (1980). the complete code predicted production cross sections for manigenes-54 radionuclide to have a peak value of 111 mb at ≈170 mev. 60 80 100 120 140 160 180 0.1 1 10 100 1000 59co(,x)51cr  (m b ) e lab (mev) michele & brinkmann,1980 complete talys-1.95 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 1-12 7 furthermore, it may be observed from table 1 that, for manganese-54 radionuclide, pearson's correlation coefficient values between theoretically anticipated on complete and experimentally quantified production cross sections confirmed moderately positive correlations. in contrast, pearson's correlation coefficient values between theoretically predicted using talys-1.95 and experimentally quantified production crosssections confirmed strong positive correlations. figure 2. the experimentally measured and theoretically predicted excitation functions for medically used manganese-54. production of iron-59 radionuclide figure 3 shows the experimentally quantified excitation functions along with theoretical predictions obtained using talys-1.95 and complete codes for iron-59 radionuclide produced via (α, x) channel in the interaction of alpha-projectile with the cobalt-59 target. using complete code, the predicted cross-section values in the energy range 55–172 mev usually agree with the experimental measurements of michel and brinkmann (1980). however, the prediction of complete code below 55 mev 30 60 90 120 150 180 0.1 10 1000 59co(, x)54mn  (m b ) e lab (mev) michel & brinkmann,1980 complete talys-1.95 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 1-12 8 underestimates the cross-section values measured by michel and brinkmann (1980). it may further be observed from figure 3 that the predicted cross-section values at low energy using the talys-1.95 code are in satisfactory agreement with the measured cross-section values of michel and brinkmann (1980). on the contrary, the predicted cross-section values at a high energy range using the talys-1.95 code underestimate the measured cross-section values of michel and brinkmann (1980). moreover, table 1 further reveals that the pearson's correlation coefficient values for the iron-59 radionuclide indicate strong positive correlations between the cross-section values predicted by the complete code and those measured by michel and brinkmann (1980). figure 3. the experimentally measured and theoretically predicted excitation functions for medically used iron-59. production of cobalt-57 radionuclide in figure 4, the measured excitation functions for the medically used cobalt-57 radionuclide produced via the complex (α, x) channel in the interaction of alpha-projectile with cobalt-59 target are clearly presented along with the theoretically predicted excitation functions by using the talys-1.95 and complete codes. using complete code, predicted production 30 60 90 120 150 180 1e-3 0.1 10 1000 59co(, x)59fe  (m b ) e lab (mev) michel & brinkmann, 1980 complete talys-1.95 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 1-12 9 cross-sections are in very good agreement with the measured values of michel and brinkmann (1980). using the talys-1.95 code, predicted production cross sections in the energy range 30 mev–90 mev are in very good agreement with the measured values (michel and brinkmann, 1980). however, predicted production cross sections using the talys-1.95 code at energies above 90 mev are in satisfactory agreement with the measured values of michel and brinkmann (1980). the complete predicted production cross sections for cobalt-57 radionuclide have a maximum value of ≈207 mb at ≈39 mev. furthermore, table 1 clearly shows and confirmed that pearson's correlation coefficient values for cobalt-57 radionuclide has strong and positive correlations between the cross-section values predicted and the values measured by michel and brinkmann (1980). figure 4. the experimentally measured and theoretically predicted excitation functions for medically used cobalt-57 production of cobalt-60 radionuclide figure 5 displays the experimentally quantified and theoretically predicted excitation functions for the medically used cobalt-60 radionuclide produced in alpha-projectile interaction with the cobalt-59 target via complex (α, x) channel. the cross-section values predicted using complete codes usually exaggerate the cross-section values measured by michel and 30 60 90 120 150 180 0.1 1 10 100 1000 59co(, x)57co  (m b ) e lab (mev) michel & brinkmann,1980 complete talys-1.95 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 1-12 10 brinkmann (1980). however, predicted production cross sections in the energy range 30 mev – 45 mev are in very good agreement with the measured values of michel and brinkmann (1980). the prediction of the talys-1.95 code underestimates the crosssection values of the measurement of michel and brinkmann (1980). moreover, the attainable value of the production cross section for cobalt60 radionuclide obtained using the complete code is about ≈343 mb at ≈39 mev. the result on table 1 further revealed that pearson's correlation coefficient values between theoretically predicted, and experimentally quantified production cross-sections confirmed strong and positive associations. figure 5. the experimentally measured and theoretically predicted excitation functions for medically used cobalt-60. 30 60 90 120 150 180 0.1 1 10 100 1000 59co(, x)60co ( m b ) e lab (mev) michel& brinkmann,1980 complete talys-1.95 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 1-12 11 table 1. pearson's correlation coefficient, r, between experimental measurements by michel and brinkmann (1980) and theoretical predictions radionuclide talys-1.95 [complete] 51cr 0.921 [0.86] 54mn 0.65 [0.92] 59fe [0.84] 57co 0.5 [0.76] 60co 0.4 [0.96] conclusion excitation functions for the production of radionuclides from the alpha-bombardment of cobalt-59 were studied for alpha-energies from 25 to 172.5 mev. the theoretical nuclear reaction model codes complet and talys1.95 were used to logically predict the medically important production cross-sections for chromium-51, mangenes-54, iron-59, cobalt59, and cobalt-60 radionuclides produced in the interaction of alpha-projectile with cobalt-59 target ≈ 25 172 mev alpha-energies. the results were compared with the measured values in the exfor data library. pearson's correlation coefficient shows a robust positive relationship between the predicted and previously observed production cross-sections for the medically relevant radionuclides chromium-51, iron-59, manganese-54, cobalt-59, and cobalt-60. further, the results show that except for chromium-51, the complete code predicts more successful outcomes than the talys1.95. acknowledgment the authors thank dr zelalem a. for his helpful scientific discussions on the present work. however, all opinions and any errors are the author's responsibility alone. references akkoyun s., bayram t. and kara s. o. 2015. photonuclear reaction cross sections for gallium isotopes. in journal of physics: conference series vol. 590, no. 1, iop publishing. amanuel k. f. 2023. production of 68ge, 68ga, 67ga, 65zn, and 64cu important radionuclides for medical applications: theoretical model predictions for αparticles with 66zn at≈ 10–40 mev. radiochim. acta. 111(3): 159-167. asres y. h., mathuthu m. and birhane m. d. 2018. analysis of reaction cross-section production in neutron induced fission reactions on uranium isotope using computer code complet. appl. radiat. isot. 139: 81-85. asres y. h., mathuthu m. and ferede y. a. 2019. investigation of nuclear reaction mechanisms of nickel isotopes at various energies induced by alpha particles. j. phys. commun. 3(11): 115018. aydin a., şarer b. and tel e. 2007. new calculation of excitation functions of proton-induced reactions in some medical isotopes of cu, zn and ga. appl. radiat. isot. 65(3): 365-370. baak m., koopman r., snoek h. and klous s. 2020. a new correlation coefficient between categorical, ordinal and interval variables with pearson characteristics. comput. stat. data anal. 152: 107043. east afr. j. biophys. comput. sci. 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(2023), vol. 4, issue. 1, 52-74 for the vast majority of geometries and problems, eq. 1 cannot be solved with analytical methods, and an approximation of the equations can be constructed with different types of discretizations. many numerical schemes have been implemented to approximately solve the ade (lima et al., 2021; mahmud, 2012; pochai and deepana, 2011; lian et al., 2016; szymkiewicz and gkakassahun getnet mekonen*, zerihun kinfe birhanu department of mathematics, college of natural and computational sciences, hawassa university, hawassa, ethiopia. in this paper, we have implemented the finite element method for the numerical solution of a boundary and initial value problems, mainly on solving the one and two dimensional advection-diffusion equation with constant parameters. in doing so, the basic idea is to first rewrite the problem as a variational equation, and then seek a solution approximation from the space of continuous piece-wise linear’s. this discretization procedure results in a linear system that can be solved by using a numerical algorithm for systems of these equations. the techniques are based on the finite element approximations using galerkin’s method in space resulting system of the first order ode’s and then solving this first order ode’s using backward euler descritization in time. for the two dimensional problems, we use the ode solver ode15i to descritize time. the validity of the numerical model is verified using different test examples. the computed results showed that the use of the current method is very applicable for the solution of the advection-diffusion equation. numerical solutions of advection diffusion equations using finite element method introduction research article equation by a test function and integration by parts (green-gauss theorem) to reduce second order derivatives to first order terms, i.e., weak formulation. then we represent the approximate solution by the linear combination of basis functions, by constructing a set of basis functions based on the mesh of our domain. that is, the solution u can be approximated by a function uh using the linear combinations of the basis functions ϕi according to the following expressions: u ≈ uh = ∑ uiϕi. (2) and we solve the linear system of equations to obtain the approximate solution. to derive the advection diffusion equations for the application of pollution models, consider an elementary water body. water quality within this body depends on the polluting substance mass present there. the water quality models describe the change in the mass of a polluting substance within the water body. the change is calculated as the difference between mass-flows (mass fluxes) entering and leaving this water body, considering also the effects of internal sources and sinks of the substance, if any. the mechanism of mass transfer into and out of this water body includes the following processes: � mass is transported by the flow, a, of the velocity vector. this process is termed as the advective mass transfer. the transfer of mass, that is the mass flux can be calculated as u × a, where u is the concentration of the substance in the water. � the dispersive mass transfer is usually expressed by the law of fix which states that the transport of east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 52 here, ϕi denotes the basis functions and ui denotes the coefficients of the functions that approximate u with uh. after this we get a system of linear equations siorowski, 2021). in numerical method, a discrete approximations for the solution is computed by descritizing the given domain in to different sets of sub domains. in this paper we were focus on finite element method to solve the pde given in eq. 1. we will implement the method for one and two dimensional pde’s. in this method, first we develop a weak formulation, from which we derive the discretization by multiplying both sides of the ade the development of finite element method has favored by the progress of computer technology and numerical calculus, and originally applied for mechanical structures (lima et al., 2021; mahmud, 2012; donea and huerta, 2003) . several procedures have been tried to interpret separately the advection and diffusion pollutant transport. the fem can help to face more complex problems and the privilege importance of the method is that it can be adapted to complex geometry domains, but the element wise intervals can assume any form of size, and obviously there is an expense of more burdensome calculations. we had to do the descritization process of the finite element method for the 1d and 2d poisson equations in which it is an auxiliary step in solving the advection diffusion equation with the fem. usually the numerical solutions of pde’ including the equation (eq. 1) are done with the finite difference method. mathematicalmodel formulation the substance in the direction of a space is proportional to the concentration of this substance in that direction and the proportionality factor being the coefficient of dispersion, d∇u. transport by advection = auda , transport by diffusion = dx ∂u ∂x , where da is an elemental cross-sectional area of the cubic element, and dx is the diffusion coefficient in the x-direction. ∂ ∂t u(x, t) + ∂ ∂x (a(x, t)u(x, t)) = ∂ ∂x ( d(x, t) ∂ ∂x u(x, t) ) + f(t, x). (3) space interval ω ⊂ r with time t ≥ 0. an initial condition u(x, 0) will be given and we also assume that suitable boundary conditions are provided, and for our work we consider the velocity field and the diffusion term as constants. pressions of the advection equation a∂u ∂x which has a first-order derivative, and the diffusion equation d ∂2u ∂x2 that has a second-order derivative. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 52 both advection and diffusion move a pollutant material from one place to another, but each accomplishes this differently. the essential difference of the advection and diffusion is that advection moves the pollutants in one way (downstream) but diffusion goes in both ways (regardless of a stream direction). this is seen in the respective mathematical exquestions are arise like, can we have cases of fast advection and relatively weak diffusion and other cases of negligible advection and fast diffusion? to answer this assuming that the two components (advection and diffusion) may be superposed, the total amount of material transported parallel to any given direction is obtained by summing the advective and diffusive transports. using the mass balance approach by equating the difference between the mass of material entering a volume element and that leaving the element (i.e., net influx of mass) to the rate of accumulation of mass inside the volume. by considering a volume element of porous mediums in three dimensional cartesian coordinates the equations are derived (bajellan, 2015). since we are considering advection and diffusion as the two modes of transport of a fluid within the porous medium, we can represent these two transport modes in the x-direction mathematically as: the multidimensional advectiondiffusion equation is used for analyzing mixing problems in rivers. one of the practical difficulties is that the equation requires some prior information about water depths, velocities, and diffusion coefficients, which could not conveniently be gathered in field experiments. in some particular mixing problems, however, some of the terms in the multidimensional advection-diffusion equation are negligibly small, so that the problem can be simplified by reducing the model to one dimension (lima et al., 2021; hundsdorfer, 1996) and the one dimensional advection diffusion equation is given in eq. 3. the time-derivative term expresses accumulation of mass at a point in space, the advection term a∇u transport of mass with the flow, and the diffusion term d∇2u reflects transport of mass due to molecular diffusion (langtangen, 1999). we shall consider the equation in the question, we must compare the sizes of the a∂u ∂x and d ∂2u ∂x2 terms to each other, and this is accomplishes by introducing scales. using these scales, we can derive estimates of the sizes of the different terms. since the derivative ∂u ∂x is expressing the difference in concentration over a distance of infinitesimal limit, we can estimate it to be approximately u x , and the advection term scales as: a ∂u ∂x ∼ v u x . similarly, the second derivative ∂2u ∂x2 represents the difference of a gradient over a specified distance and is estimated at ( u x ) x = u x2 , and the diffusion term scales as: d ∂2u ∂x2 ∼ d u x2 . equipped with these estimates, we can then compare the two processes by forming the ratio of their scales: advecton diffusion = v u x d u x2 = v x d this ratio is dimensionless and traditionally, it is called the peclet number and is denoted by pe: pe = v x d . if pe ≪ 1 (if pe < 0.1): the advection term will result significantly smaller than the diffusion term. physically, diffusion dominates and advection is negligible. so, spreading occurs symmetrically despite of the flow of the directional bias. if we wish to simplify the problem, we may drop the a∂u ∂x term, as if a were nil (no amount at all). the relative error occurred in the solution is expected to be on the order of the peclet number, and the smaller pe leads to the smaller error. the solutions established with diffusion only were based on such simplification and are thus valid as long as pe ≪ 1. if pe ≫ 1 (if pe > 10): the advection term is significantly bigger than the diffusion term. physically, the diffusion term is negligible and advection dominates, and spreading is existent, with the patch (small area) of pollutant being simply moved along by the flow. if we wish to simplify the problem, we may drop the d ∂2u ∂x2 term, as if d were zero. the relative error occurred in doing the solution is expected as the order of the peclet number inverse (1/p e), and the larger p e will result the smaller error. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 55 if p e ∼ 1 (in practice, if 0.1 < p e < 10): the advection and diffusion terms are not significantly different which results for the non dominance of the two in the process. the full equation must be utilized as there will no approximation to the equation will be justified. variable scale choice of value u u the concentration value such as initial, boundary, or average value a v the maximum velocity value x x approximate length of the domain or size of release location in this paper we use the finite element method (fem) to approximate the solution of the advection diffusion equation. the method is examined as an emerging tool for the approximate solution of differential equations describing different physical processes (yang et al., 2020). it is based on the basic finite e lement procedures, those are: the variation form fornumerical method mulation of the problem, the discretization of the formulation in a finite element, and the solution of the resulting finite element equations. fem cuts a given domain into several elements (pieces of the domain) and connected in a finite number of nodal points. finite element implementation of the 1d governing equation let us consider the one dimensional advection-diffusion equation given by: ∂u ∂t + a ∂u ∂x = d ∂2u ∂x2 + f, u(0) = u(1) = 0, (4) where u is the concentration of the pollutant, a is the velocity, f is the source term, and d is the diffusion coefficient, with all the three variables be constants. implementation of the 1d advection equation let we first consider only an advection equation, that is the diffusion term does not exist; ∂u ∂t + a ∂u ∂x = 0. the first step is constructing a variational or weak formulation, by multiplying both sides of the differential equation by a test function v(x) satisfying the boundary conditions (bc) v(0) = 0, v(1) = 0 and v ∈ h1 0 (0, 1), where h1 0 (0, 1) is the sobolev space, h1 0 (0, 1) = {v ∈ l2(0, 1); v′ ∈ l2(0, 1)}, and it is a function space where all the functions are bounded. let us now define a sub-space of h where we can find our solution u. we call this v and v = {v ∈ h(x) : v|∂ω = 0}, where ω is our domain, then multiplying and integrating both sides in the domain we have that: ∂u ∂t .v + a ∂u ∂x .v = 0, ∫ 1 0 ( ∂u ∂t .v + a ∂u ∂x .v ) = 0. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 56 the fem is based on the integration of the terms in the equation to be solved, in form of point discretization schemes. it utilizes the method of weighted residuals and integration by parts (green-gauss theorem) to reduce second order derivatives to first order terms. the solution domain is discretized into individual elements and these elements are operated upon individually and then solved globally using matrix solution techniques. such a task could be done automatically by a computer, but it necessitates an amount of mathematical skill that to day still requires human involvement, (brenner et al., 2008). the theories of finite element methods provided the reasons why it worked well for the class boundary/initial value problems (lima et al., 2021; ahsan, 2012; larson and bengzon, 2010). extension of the mathematical basis to nonlinear and non-structural problems was achieved through the method of weighted residuals (mwr), originally conceived by galerkin in the early 20th century. the basics of the method requires multiplying of the governing differential equation by a set of predetermined weights and integrating the resulting product over a region. most of the finite element method uses the galerkin’s method to establish the approximations of the governing equations, (aragonés et al., 2019; lima et al., 2021; ahsan, 2012; yang et al., 2020; brenner et al., 2008). it allows us to convert a continuous form of the problem, such as the weak formulation for the partial differential equation into a discrete problem that may be solved numerically. that is;∫ 1 0 ∂u ∂t .v + ∫ 1 0 a ∂u ∂x .v = 0, (5) which is the weak formulation of the one dimensional advection equation. advantages of weak form compared to strong form equation 5 is the final weak formulation. it is equivalent to the strong form, since we can reverse all the steps, and get back to the original equation. firstly, if we look at the strong form, we have two separate partial derivatives of u, so the strong form requires that u be continuously differentiable until at least second partial derivative. our new formulations has lowered this requirement to only first partial derivatives by transforming one of the partial derivatives onto the weightfunction v(x, y). this is the first big advantage of a weak formulation. the subspace v is not difficult to understand; it is a subspace of h because our weak form requires that the functions are in h; our strong form requires that u be 0 along the boundary, so v is the subspace of all function which are zero on the boundary. ih, i = 0, 1, ..., n, where h = 1 n , and ϕi(xj) = δij, i, j = 1, ..., n− 1, (6) where δij being the kronecker delta. the function ϕi is therefore piece wise linear and are fix with one node (vertex) and figure 1: the basis (hat) function ϕi associated to node xj, in this figure φi on a mesh. also shown is the half hat ϕ0. its expression is given by ϕi(x) =  x−xi−1 xi−xi−1 , if xi−1 ≤ x ≤ xi xi+1−x xi+1−xi , if xi ≤ x ≤ xi+1 0, other wise , for i = 1, 2, . . . , n− 1. (7) that is, ϕi(xj) = δij = { 1, if i = j 0, if i ̸= j . (8) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 57 the next step is to generate a mesh, let be a uniform cartesian mesh xi = associate the value one to this node and zero at the remaining nodes of the partition (see fig. 1, (larson and bengzon, 2010)). we define the intervals as [xi−1, xi], i = 1, 2, ..., n. after generating a mesh we construct a set of basis functions based on the mesh for each intervals, such as the piece wise linear functions for i = 1, 2, ..., n− 1. the characteristic basis functions are characterized by the following property, (quarteroni and quarteroni, 2009) uh(x) = n−1∑ j=1 cjϕi(x), (9) where the coefficients cj are the unknowns to be determined. since the hat (basis) functions are piece wise linear, uh(x) is also a piece wise linear function, although this is not usually the case for the true solution u(x), and here we have, uh(xj) = n−1∑ i=1 cjϕi(xj) = cj. we then derive a linear system of equations for the coefficients by substituting the approximate solution uh(x) for the exact solution u(x) in the weak form: u(t, x) = n−1∑ i=1 uiϕi(x), (10) v(t, x) = n−1∑ j=1 vjϕj(x). (11) now substituting eq.10 and eq.11 in the weak formulation of the equation eq.5, we have: ∫ 1 0 ∂ ∂t n−1∑ i=1 uiϕi. n−1∑ j=1 vjϕj + ∫ 1 0 a ∂ ∂x ( n−1∑ i=1 uiϕi ) . n−1∑ j=1 vjϕj = 0. which then implies, n−1∑ j=1 vj ( ∂ ∂t n−1∑ i=1 ui ∫ 1 0 ϕi.ϕj + a n−1∑ i=1 ui ∫ 1 0 ϕ′ i.ϕj ) = 0. that is ∂ ∂t n−1∑ i=1 ui ∫ 1 0 ϕi.ϕj + a n−1∑ i=1 ui ∫ 1 0 ϕ′ i.ϕj = 0. in a matrix form it can be written as: mu̇ + abu = 0, (12) where, east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 58 we use this hat (basis) functions through out the 1d space of this research using equal spaced step size (xi+1−xi = h, for all i). we say that the functions are basis for the following reasons. if we want to approximate our continuous function u with a piece wise continuous linear functhen let the approximate solution for u be given by a linear combination of basis functions ϕi = δij, as given in eq. 10, and also for v as in eq. 11. now we find a finite element solution of the discrete problem by using the hat functions ϕi(x) defined in eq. 7. for the given basis function the approximation of u and v can be written as : tion u′, these functions are what we need. these functions are linearly independent of each other; it is not possible to make one out of a combination of others. for example, only one of these functions, ϕi, is non-zero (equal to 1) at node i. the next step in approximating a pde with fem is represent the approximate (fe) solution by the linear combination of such basis functions, (quarteroni and quarteroni, 2009) as � m is the mass matrix with entries: mi,j = ∫ 1 0 ϕi(x)ϕj(x)dx. � b is a matrix with entries: bij = ∫ 1 0 ϕ′ i(x)ϕj(x)dx =  0, if i = j −1 2 , if i− j = 1 1 2 , if j − i = 1 0, other wise . (13) m ( un+1 − un ∆t ) + abun+1 = 0. here un denotes u at time t = tn = ∆tn, and ∆t is the time step. rearranging the terms we obtain the system:( m ∆t + ab ) un+1 = 1 ∆t mun, n = 0, 1, 2, . . . , to be solved for un+1 by using initial condition for u0 = u(x, t = 0). assembly of the mass matrix m in 1d ∫ ω ϕiϕjdx exactly. moreover, since the hats ϕi and ϕj figure 2: illustration of the hat functions ϕi−1 and ϕi, in this figure φ, and their support. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 59 the next step is to descritize the sys-tem eq.12 in time. here we were consider finite difference approximations specially the implicit euler (back ward euler) method. by using the back ward euler scheme, the system eq.12 results the following system of algebraic equations: euler back ward represents an implicit scheme which is stable for all choices of ∆t (?). since the scheme is implicit, we have to solve a system of algebraic equations at each time step. lack common support for |i− j| > 1 only mi,i, mi,i+1 , and mi+1,i need to be calculated. all other matrix entries are zero by default. this is clearly seen from figure 2, (larson and bengzon, 2010) showing two neighboring hat functions and their support. as a consequence, the mass matrix m is tridiagonal. let us now go through the details of how to assemble the mass matrix m . we begin by calculating the entries mi,j of the mass matrix, which involve products of hat functions given in eq. 7. since each hat is a linear polynomial, the product of two hats is a quadratic polynomials. thus, simpson’s formula (eq. 18) can be used to integrate mi,j = here m and a are tridiagonal matrices and eq.12 is a simple system of ode. a f(x)dx = f(a) + 4f(a+b 2 ) + f(b) 6 (b−a). (14) let we start on the diagonal entries of m , mi,i using simpson’s formula: mi,i = ∫ ω ϕ2 i dx, = ∫ xi xi−1 ϕ2 i dx+ ∫ xi+1 xi ϕ2 i dx, = 0 + 4(1 2 )2 + 1 6 hi + 1 + 4(1 2 )2 + 0 6 hi+1, = hi 3 + hi+1 3 , for i = 1, 2, . . . , n− 1, where hi+1 = xi+1−xi and hi = xi−xi−1, but in our case we use a uniform mesh length h = xi+1 − xi = xi − xi−1 and mii = 2h 3 . the first and last diagonal entry are m00 = h1 3 and mnn = hn 3 , respectively, since the hat functions ϕ0 and ϕn are only half. formula we have mi+1,i = ∫ ω ϕi+1ϕidx, = ∫ xi+1 xi ϕi+1ϕidx, = 1.0 + 4(1 2 )2 + 0.1 6 hi+1 = hi+1 6 , for i = 0, 1, 2, . . . , n− 1. by using a similar calculation the super diagonal entries mi,i+1 have the values mi,i+1 = hi+1 6 , for i = 0, 1, 2, . . . , n− 1. hence, the mass matrix m takes the form m =  h1 3 h1 6 h1 6 h1 3 + h2 3 h2 6 h2 6 h2 3 + h3 3 h3 6 . . . . . . . . . hn−1 6 hn−1 3 + hn 3 hn 6 hn 6 hn 3  . (15) the global mass matrix m can be written as a sum of n simpler elemental matrices as: m =  h1 3 h1 6 h1 6 h1 3 +  h2 3 h2 6 h2 6 h2 3 + . . .+  hn 3 hn 6 hn 6 hn 3  . i.e., m = mω1 +mω2 + . . .+mωn . e m e = h 6 [ 2 1 1 2 ] , where h is the length of e. we refer to m e as the local element mass matrix. the summation of the element mass matrices into the global mass matrix is called assembling. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 60 on the interval i = (a, b), simpson’s formula is of the form, (larson and bengzon, 2010)∫ b we know continue with the sub diagonal entries mi+1,i still using simpson’s , i = 1, 2, . . . , n, is obtained by restricting the integration to one sub interval or element ωe and is therefore called an element mass matrix. from the sum we see that on each element e this small block takes the form: each matrix mω implementation of the 1d diffusion equation let we now consider the diffusion equation ∂u ∂t = d ∂2u ∂x2 . we multiply the equation by a test function v(x), which satisfies the boundary conditions v(0) = v(1) = 0 and then integrating by parts we have that: ∂u ∂t .v = d ∂2u ∂x2 .v ∫ 1 0 ( ∂u ∂t .v ) = ∫ 1 0 ( d ∂2u ∂x2 .v ) hence by using integration by parts, we obtain∫ 1 0 ∂u ∂t .v = −d ∫ 1 0 ∂u ∂x . ∂v ∂x , (16) which is the weak formulation of the one dimensional diffusion equation. ∫ 1 0 ∂ ∂t n−1∑ i=1 uiϕi. n−1∑ j=1 vjϕj = −d ∫ 1 0 ∂ ∂x n−1∑ i=1 uiϕi. ∂ ∂x n−1∑ j=1 vjϕj. which then implies, n−1∑ j=1 vj ( ∂ ∂t n−1∑ i=1 ui ∫ 1 0 ϕi.ϕj ) = n−1∑ j=1 vj ( −d n−1∑ i=1 ui ∫ 1 0 ϕ′ i.ϕ ′ j ) . that is ∂ ∂t n−1∑ i=1 ui ∫ 1 0 ϕi.ϕj = −d n−1∑ i=1 ui ∫ 1 0 ϕ′ i.ϕ ′ j. in a matrix form it can be written as: mu̇ +dau = 0, (17) assembly of the stiffness matrix in 1d the stiffness matrix a is symmetric for this simple problem, which makes the computation of the matrix faster since we don’t have to compute all of the elements, symmetric matrices are also much faster to invert. here ϕi’s are the hat functions given in eq. 7, the entries of each element of the stiffness matrix a is given by east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 61 now the system of equation, that is eq.12 is a simple system of ordinary differential equations. to solve this system of ode’s, we have to use a back ward euler method and a matlab soft ware to solve the system at each time steps using an initial condition. where m is the mass matrix with entries given in eq. 15 and a is the stiffness matrix with entries given in eq. 19. here the matrix a is often referred to as the stiffness matrix, a name coming from corresponding matrices in the context of structural problems. now substituting eq.10 and eq.11 in the weak formulation of the equation eq.16, we have: ai,j = ∫ 1 0 ϕ′ iϕ ′ jdx, = n−1∑ e=1 ∫ ωe ϕ′ iϕ ′ jdx, = n−1∑ e=1 ae ij. similarly the load vector fi = ∫ 1 0 fϕidx = n−1∑ e=1 ∫ ωe fϕidx = n−1∑ e=1 f e i . a f(x)dx = f(a) + 4f(a+b 2 ) + f(b) 6 (b− a). (18) then we can be illustrate by the hat functions and simpsons formula as follows: ϕi(x) =  x−xi−1 hi , if xi−1 ≤ x ≤ xi xi+1−x hi+1 , if xi ≤ x ≤ xi+1 0, other wise , ϕi−1(x) =  x−xi−2 hi−1 , if xi−2 ≤ x ≤ xi−1 xi−x hi , if xi−1 ≤ x ≤ xi 0, other wise , and ϕi+1(x) =  x−xi hi+1 , if xi ≤ x ≤ xi+1 xi+2−x hi+2 , if xi+1 ≤ x ≤ xi+2 0, other wise . now ai,i = a(ϕi, ϕi) e = ∫ ωe ϕ′ iϕ ′ idx, = ∫ xi xi−1 ϕ′ iϕ ′ idx+ ∫ xi+1 xi ϕ′ iϕ ′ idx, = ∫ xi xi−1 1 hi 1 hi dx+ ∫ xi+1 xi −1 hi+1 −1 hi+1 dx, = hi 6 ( 1 h2 i + 4 h2 i + 1 h2 i ) + hi+1 6 ( 1 h2 i+1 + 4 h2 i+1 + 1 h2 i+1 ) , = 1 hi + 1 hi+1 . , ai−1,i = a(ϕi−1, ϕi) e = ∫ ωe ϕ′ i−1ϕ ′ idx, = ∫ xi xi−1 ϕ′ i−1ϕ ′ idx+ ∫ xi+1 xi ϕ′ i−1ϕ ′ idx, = ∫ xi xi−1 −1 hi 1 hi dx, = hi 6 ( −1 h2 i + −4 h2 i + −1 h2 i ) = −1 hi . east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 62 on the interval i = (a, b) simpson’s formula is of the form, (larson and bengzon, 2010)∫ b and ai,i+1 = a(ϕi+1, ϕi) e = ∫ ωe ϕ′ i+1ϕ ′ idx, = ∫ xi xi−1 ϕ′ i+1ϕ ′ idx+ ∫ xi+1 xi ϕ′ i+1ϕ ′ idx, = ∫ xi+1 xi −1 hi+1 1 hi+1 dx, = hi+1 6 ( −1 h2 i+1 + −4 h2 i+1 + −1 h2 i+1 ) = −1 hi+1 . each generic interior element contributes to the stiffness matrix of a 2× 2 sub matrix. a = ∫ 1 0 ϕ′ iϕ ′ jdx = n−1∑ e=1 ae =  1 h1 −1 h1−1 h1 1 h1 + 1 h2 −1 h2 −−1 h2 1 h2 + 1 h3 −1 h3 . . . . . . . . . −1 hn−1 1 hn−1 + 1 hn −1 hn −1 hn 1 hn  . (19) the global stiffness matrix a can be written as a sum of n simpler elemental matrices as: a = 1 h1  1 −1 −1 1 + 1 h2  1 −1 −1 1 + . . .+ 1 hn  1 −1 −1 1  . i.e., a = aω1 + aω2 + . . .+ aωn . each matrix aωe , e = 1, 2, . . . , n, is obtained by restricting the integration to one sub interval or element ωe and is therefore called an element stiffness matrix. from the sum we see that on each element e this small block takes the form: ae = 1 h [ 1 −1 −1 1 ] , where h is the length of e. we refer to ae as the local element stiffness matrix. implementation of one dimensional advection diffusion equation let us now solve the 1d governing (advection diffusion) equation ∂u ∂t + a ∂u ∂x = d ∂2u ∂x2 + f, u(0) = u(1) = 0, by using fem. let we find the weak formulation of the equation by multiplying the equation with a test function v(x), which satisfies the boundary conditions v(0) = v(1) = 0 and then integrating by parts as the same procedure above. we have that: ∂u ∂t .v + a ∂u ∂x .v = d ∂2u ∂x2 .v + f.v,∫ 1 0 ( ∂u ∂t .v + a ∂u ∂x .v ) = ∫ 1 0 ( d ∂2u ∂x2 .v + f.v ) . using integration by parts, we have then east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 63 now the system of equation, that is eq.17 also is a simple system of ordinary differential equations and we can solve this system of ode’s to get the solution of the original pde. ∫ 1 0 ∂u ∂t .v + ∫ 1 0 a ∂u ∂x .v = −d ∫ 1 0 ∂u ∂x . ∂v ∂x + ∫ 1 0 f.v, (20) ∫ 1 0 ∂ ∂t n−1∑ i=1 uiϕi. n−1∑ j=1 vjϕj + ∫ 1 0 a ∂ ∂x ( n−1∑ i=1 uiϕi ) . n−1∑ j=1 vjϕj = −d ∫ 1 0 ∂ ∂x n−1∑ i=1 uiϕi. ∂ ∂x n−1∑ j=1 vjϕj + ∫ 1 0 f. n−1∑ j=1 vjϕj. which then implies, n−1∑ j=1 vj ( ∂ ∂t n−1∑ i=1 ui ∫ 1 0 ϕi.ϕj + a n−1∑ i=1 ui ∫ 1 0 ϕ′ i.ϕj ) = n−1∑ j=1 vj ( −d n−1∑ i=1 ui ∫ 1 0 ϕ′ i.ϕ ′ j + ∫ 1 0 f.ϕj ) . (21) that is ∂ ∂t n−1∑ i=1 ui ∫ 1 0 ϕi.ϕj + a n−1∑ i=1 ui ∫ 1 0 ϕ′ i.ϕj = −d n−1∑ i=1 ui ∫ 1 0 ϕ′ i.ϕ ′ j + ∫ 1 0 f.ϕj. in a matrix form it can be written as: mu̇ + abu +dau = f, (22) assembly of the load vector in 1d the interval [a, b] with h = b−a n , xi = a+ih for each i = 0, 1, . . . , n : ∫ b a f(x)dx = h 3 f(x0) + 2 n 2 −1∑ j=1 f(x2j) + 4 n 2∑ j=1 f(x2j−1) + f(xn)  , j = 1, 2, ..., ( n 2 )− 1. (23) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 64 which is the weak formulation of the one dimensional advection-diffusion equation. substituting eq.10 and eq.11 where m is the mass matrix with entries given in eq. 15, b is a matrix with entries given in eq. 13, a is the stiffness matrix given in eq. 19 and f is a load vector given in eq. 25. the right-hand-side, load vector of eq. 20 contains an integral over a function f(x). in general, exactly computing this integral is very difficult, so another numerical approximation is required. we can use a well known integration rule composite simpson rule to approximate these integration whose formula (for more information you can see, (?)) is given in eq. 23, by selecting a set of distinct n nodes in in the weak formulation of the equation eq.20, we have: ∫ b a f(x)dx = f(a) + f(b) 2 (b− a), (24) we have fi = ∫ i fϕidx, = ∫ xi+1 xi−1 fϕidx, = ∫ xi xi−1 fϕidx+ ∫ xi+1 xi fϕidx, ≈ f(xi−1)ϕi(xi−1) + f(xi)ϕi(xi) 2 hi + f(xi+1)ϕi(xi+1) + f(xi)ϕi(xi) 2 hi+1, = 0 + f(xi) 2 hi + f(xi) + 0 2 hi+1, = f(xi) ( hi 2 + hi+1 2 ) . now using this trapezoidal method, the approximate load vector takes the form f =  f(x0) h1 2 f(x1) ( h1+h2 2 ) f(x2) ( h2+h3 2 ) ... f(xn−1) ( hn−1+hn 2 ) f(xn) hn 2  . (25) splitting f into a sum over the elements yields the n global element load vectors fωe : f =  f(x0) f(x1)  h1 2 +  f(x1) f(x2)  h2 2 +  f(x2) f(x3)  h3 2 + . . .+  f(xn−1) f(xn)  hn 2 i.e., f = fω1 + fω2 + . . . + fωn . each vector fωe , e = 1, 2, . . . , n, is formally derived by restricting the integration to element ωe. mu̇ + (ab +da)u = f, (26) which is a simple system of ordinary differential equations. for solving this system of ode’s, we have to use a matlab soft ware in which it has a number of tools for numerically solving ordinary differential equations. we would focus on the back ward euler method to descritize time. fem implementation of the two dimensional ad equation the 2d advection diffusion equation with the same and constant velocity and diffusion term is given by ut+a(ux+uy) = d(uxx+uyy)+f, (x, y) ∈ ω = [0, 1], east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 65 using the another quadrature rule for simplicity, for instance, using the trapezoidal rule, (larson and bengzon, 2010) now the system of equation, that is eq.22 can be written in the form: with homogeneous boundary conditions. that is ut + a∇u = d∇2u+ f. now to find a weak formulation for this 2d equation, we multiply both sides of the equation with a test function v = v(x, y) ∈ v which satisfies the boundary conditions. ut.v + a∇u.v = d∇2u.v + fv. here integrating this over the domain ω yields the following: ∫ ω (ut.v + a∇u.v) = ∫ ω ( d∇2u.v + fv ) . we see from the 2d fem of poisson equation (using gauss theorem and the transformation of a surface integral to a line integral) that ∫ ω v∇2u = − ∫ ω ∇v∇u, and hence we get: ∫ ω (ut.v + a∇u.v) = −d ∫ ω (∇v∇u) + ∫ ω fv.∫ ω ut.v = − ∫ ω (d∇v∇u+ a∇u.v) + ∫ ω fv. (27) (ut, v) = l(u, v) + (f, v) ∀v ∈ v, (28) where (ut, v) = ∫ ω ut.v and l(u, v) = − ∫ ω (d∇v∇u+ a∇u.v). given a fe space v , with ϕi(x, y), i = 1, 2, . . . , n denoting a set of basis functions for v , we seek the fe solution of form uh(x, y, t) = n∑ j=1 uj(t)ϕj(x, y). (29) and taking the test function v(x, y) as a linear combination of basis functions v(x, y) = n∑ j=1 vjϕj, with vj are constants. (30) ∑ j=1 u′ j(t)ϕj(x, y), n∑ j=1 vjϕj ) = l ( n∑ j=1 uj(t)ϕj(x, y), n∑ j=1 vjϕj ) + (f, n∑ j=1 vjϕj). (31) then we get the linear system of ordinary differential equations in the uj(t) as:( u′ 1(t)ϕ1(x, y) + n∑ j=2 u′ j(t)ϕj(x, y), n∑ j=1 vjϕj ) = l ( u1(t)ϕ1(x, y) + n∑ j=1 uj(t)ϕj(x, y), n∑ j=1 vjϕj(x, y) ) + (f, n∑ j=1 vjϕj(x, y)), east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 66 substituting this expression (29 and 30) into eq.28, we obtain( n here eq. 27 is the weak formulation and it can be simplified as ( u′ 1(t)ϕ1, n∑ j=1 vjϕj ) + ( n∑ j=2 u′ j(t)ϕj, n∑ j=1 vjϕj ) = l ( u1(t)ϕ1, n∑ j=1 vjϕj ) + l ( n∑ j=1 uj(t)ϕj, n∑ j=1 vjϕj ) + (f, n∑ j=1 vjϕj), n∑ j=1 ( u′ j(t)ϕj, n∑ j=1 vjϕj ) = n∑ j=1 l ( uj(t)ϕj, n∑ j=1 vjϕj ) + (f, n∑ j=1 vjϕj), n∑ j=1 n∑ j=1 ( u′ j(t)ϕj, vjϕj ) = n∑ j=1 n∑ j=1 l (uj(t)ϕj, vjϕj) + n∑ j=1 (f, vjϕj). since vj’s are constants we have also that: n∑ j=1 vj n∑ j=1 (ϕj, ϕj)u ′ j(t) = n∑ j=1 vj n∑ j=1 l (ϕj, ϕj)uj(t) + n∑ j=1 vj(f, ϕj). the corresponding problem can therefore be expressed as v tmu̇ = v tau + v tf. that is mu̇ = au + f. (32) where, m =  (ϕ1, ϕ1) (ϕ1, ϕ2) . . . (ϕ1, ϕn) (ϕ2, ϕ1) (ϕ2, ϕ2) . . . (ϕ2, ϕn) ... ... ... (ϕn , ϕ1) (ϕn , ϕ2) . . . (ϕn , ϕn) , a =  l(ϕ1, ϕ1) l(ϕ1, ϕ2) . . . l(ϕ1, ϕn) l(ϕ2, ϕ1) l(ϕ2, ϕ2) . . . l(ϕ2, ϕn) ... ... ... l(ϕn , ϕ1) l(ϕn , ϕ2) . . . l(ϕn , ϕn) , and f =  (f, ϕ1) (f, ϕ2) ... (f, ϕn)  . in this section, we are compared for the advection-diffusion equations with an exact solution for the given finite element methods and then we solve the equation with out knowing the exact solution. the comparison is carried out by means of computed solutions for a wide range east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 67 there are many methods to solve the above problem involving the system of first order ode. we can use fd methods that will descritize in time by using explicit euler method, implicit euler method or the crank-nicolson method, by considering an appropriate initial condition, (johnson, 2012). but for this paper in the two dimensional case, we can use the ode suite in matlab which is the matlab build in system of ode solver, ode15i. results and discussion of characteristic parameters. linear elements are employed at the discretization in case of one-dimensional problem and bilinear elements in case of twodimensional problems. dirichlet and general boundary conditions are considered with different initial conditions and different size of computational domain. x2) + t cos(πx)(1 − 2x) and the velocity parameter a = 3, with homogeneous boundary conditions. the fm solution using matlab with a back ward euler descritization in time is given in fig. 3(a), with n = 100 nodes. to saw our error the exact solution for this equation is u(x, t) = t cos(πx)(x−x2) and its graph is of nodes from n = 100 to n = 1000, then our numerical solution becomes more accurate and we saw that the error is an order of 10−7 by modifying h = 0.001 from the algorithm. (a) fem solution (b) exact solution figure 3: the matlab implementation of the advection dominated equation with f(x, t) = cos(πx)− atπ sin(πx)(x− x2) + t cos(πx)(1− 2x). tively large diffusion coefficient, the diffusion process is faster. hence our finite element method is reasonable and accurate. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 68 fig. 3(b). the error of this equation is an order of 10−4. if we increase the number in (bergara, 2011), there is a diffusion (ut = duxx) example solved with finite difference methods, and let we solve that equation with the finite element method. he solves the diffusion (heat) equation by using initial condition u(x, 0) = sin(πx) first, consider the advection equation ut + aux = f with sources and sinks function, f(x, t) = cos(πx) − atπ sin(πx)(x − when we saw the results of those figures (fig. 4 to fig. 6) we can observe the following. if we use a small amount of diffusion coefficient, then it has a mall diffusion process and if we consider relaand with homogeneous dirichlet boundary conditions in the interval 0 ≤ x ≤ 1. if we consider different values for final time and diffusion coefficient we get the following simulations (fig. 4 to fig. 6) with a similar descritization of space (x) in to 50 nodes. (a) fem sol. with d = 0.1 and tf = 0.5 (b) fem sol. with d = 1 and tf = 0.5 figure 4: solution of the diffusion equation using d = 0.1 and d = 1 for a constant final time of tf = 0.5. (a) fem sol. with d = 10 and tf = 0.5 (b) fem sol. with d = 0.1 and tf = 3 figure 5: solution of the diffusion equation using d = 10 with tf = 0.5 and d = 0.1 for final time of tf = 3. sin(πx) (1 +dπ2t) + aπt cos(πx), u(x, 0) = 0, u(0, t) = u(1, t) = 0. by using the forward euler descritization in pe = al d = 0.003 ≪ 1 which is diffusion dominated for this choice of a and d. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 69 time the matlab implementation with a = 0.03 and d = 10 for this problem is given in fig. 7. the peclet’s number let we know consider the ade ut + aux − duxx = f with f(x, t) = since we implements zero flux concentrations of the pollutants in the boundaries, the total mass of the pollution should remain constant. these boundaries physically correspond to a system where the species is enclosed inside a mesh that it cannot penetrate, however, the mesh allows the fluids to diffuse through the flow field. we see that all masses eventually concentrate along the domain as we have seen in fig. 7. this steady state corresponds to diffusive and advective fluxes balancing each other. the flow carries additional mass towards the domain, but the density gradient limits how much more mass can be deposited. (a) fem sol. with d = 1 and tf = 3 (b) fem sol. with d = 10 and tf = 3 figure 6: solution of the diffusion equation using d = 1 and d = 10 for a constant final time of tf = 0.5. (a) fem solution (b) bar plot of the solution figure 7: implementation of 1d ad equation with the source functionf(x, t) = sin(πx) (1 +dπ2t) + aπt cos(πx) and homogeneous dirichlet boundary conditions and a = 0.03, d = 10, in which the peclet’s number pe = al d = 0.003 ≪ 1 which is diffusion dominated. ary condition dux(0, t) = k0(u(0, t) + g0 and −dux(1, t) = k1(u(1, t) + g1 and by considering different robin boundary paeast afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 70 we see know on an arbitrary input concentration by using neumann and robin boundary conditions. here, the problem is undetermined because of an unknown input concentration and hence unknown exit concentration and depends on the parameters. authors of previous works on problems of this type have done on a known exit concentration by assuming a continuous and constant concentration at the flow boundary of dirichlet type. this yields we to consider a problem by forcing the flow boundaries using neumann and robin boundary conditions. this conditions yields the flow of the concentration to move freely. here the velocity term and the diffusion coefficient highly affects the flow of the concentration. we saw it by giving a source function f(x, t) = a(2x + 1) − 2d − 1, 0 ≤ x ≤ 1, 0 ≤ t ≤ tf with a robin boundrameters. 2 (a) fem solution with tf = 1 (b) fem solution with tf = 3 figure 8: numerical solution using fem for the advection diffusion equation with f(x, t) = a(2x + 1) − 2d − 1 and robin boundary conditions, with a diffusion coefficient d = 0.02 and velocity term a = 1 with time tf = 1 for (a) and tf = 3 for (b). u(t, x, y) = e−t sin(πx) sin(πy) be the given exact solution for the diffusion equation ut − d∆u = f , then our source function f becomes f(t, x, y) = (2dπ2 − 1)e−t sin(πx) sin(πy). now by using the east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 71 let we change the velocity term and the diffusion coefficient for the given source term using d = 0.02 and a = 1, (g0, g1) = (0.02, 0.06). the solution for sion equation with a source function given as f(x, y) = dπ2(sin(πx)+sin(πy)) to imlet we consider the 2d steady diffuin order to consider the finite element method of the time dependent two dimensional equations, we use the unsteady 2d diffusion equation. let we test it with a known exact function and use the source terms and boundary conditions from that function. let plement the 2d problem. the fem numerical simulation of the pde is given in fig. 9. ode15i, ode solver to integrate for time in the final finite element method descritization the solutions for the equation is given in fig. 10. the surface plots of those figures are the exact solutions, the finite element method solutions and the color bar of the finite element solution to view its properties. this conditions is given in fig. 8(a) using a total time of tf = 1 and 8(b) using a total time of tf = 3. this is an advection dominated example in which the movement of the concentration is faster in advection terms relative to diffusion. (a) fem solution (b) bar plot of the solution figure 9: the numerical simulation using fem for the steady 2d diffusion equation with f(x, y) = dπ2(sin(πx) + sin(πy)), with a diffusion coefficient d = 0.5. (a) fem & exact sol (b) colour bar of the fem solution figure 10: the surface of time dependent two dimensional diffusion equation with d = 100 with its color bar plot for its source term f , f(t, x, y) = (2dπ2−1)e−t sin(πx) sin(πy). method to solve any differential equations numerically in any type of geometries. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 72 if we consider another linear test example with exact solution u(x, y, t) = x+ y + t, then its source function becomes f(x, y, t) = 1. the finite element solution the numerical results in all the above mentioned discussions using the finite element method are almost closed to the analytical solution in the case of the test examples. this shows us that the finite element method is one of the best numerical for this 2d unsteady diffusion equation with its exact solution and color bar is given in fig. 11 by ode solver ode15i. (a) fem & exact sol (b) colour bar of the fem solution figure 11: the surface of time dependent two dimensional diffusion equation with d = 1 with its color bar plot for its source term f , f(t, x, y) = 1. sional and two dimensional cases with the weighted residual (galerkin) method of finite elements with constant velocity term and diffusion coefficient. these statements are supported by our test numerical investigations for the one and two dimensional poisson equation, the advection equation, diffusion equation and the advection-diffusion equation. we have also seen the simulations of the equations by using the language of technical computing called matlab and for time dependent equation using backward (implicit) euler finite difference method for one dimensional problem and the builtin function ode15i to solve the system of ode’s for two dimensional equations. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 73 the generalization of the proposed galerkin method to the three-dimensional advection diffusion is obtained within the current framework and an interested body will be done on this approach by including the reaction term. to obtain the solutions to this problems, the method can be extended to the least square finite element method, and another interested body will also be done on this approach. one can also extend this method using variable velocities and diffusion coefficients whichwe have solved the advectiondiffusion e quation f or b oth o ne dimenin this paper, we study the finite element solution of the advection-diffusion equation. in the finite e lement analysis, we approximate a function defined in a domain, ω, with a set of orthogonal basis functions with coefficients corresponding to the functional values at some node points. we deal with the numerical simulation of the advection-diffusion equation using the finite e lement method scheme in space and the backward euler method in time. the main focus of the paper has been on the variational formulation techniques for the solution of the discrete galerkin method and the other hand on computational analysis of different one and two dimensional pde’s. we have done numerical simulations for the above mentioned equations by considering the technique and using different test examples. the solution for the values at the nodes for the partial differential equations can be obtained by solving a linear system of equations involving the inversion of the sparse matrices. conclusions east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 52-74 hundsdorfer w.1996. numerical solution of advectiondiffusion-reaction equations: lecture notes for ph. d. course, 1996, thomas stieltjes institute. department of numerical mathematics [nm], (9603). johnson c. 2012. numerical solution of partial differential equations by the finite element method. courier corporation. langtangen h.p. 2003. computational partial differential equations: numerical methods and diffpack programming (vol. 2). berlin: springer. larson m.g. and bengzon f. 2010. the finite element method: theory, implementation, and practice. texts in computational science and engineering, 10, 23-44. lian y., ying y., tang s., lin s., wagner g.j. and liu w.k. 2016. a petrov–galerkin finite element method for the fractional advection– diffusion equation. comput. methods appl. mech. eng., 309: 388-410. lima s.a., kamrujjaman m. and islam m.s. 2021. numerical solution of convection–diffusion– reaction equations by a finite element method with error correlation. aip advances 11(8): 085225. pochai n. and deepana r. 2011. a numerical computation of water quality measurement in a uniform channel using a finite difference method. procedia eng. 8: 85-88. quarteroni a. and quarteroni s. 2009. numerical models for differential problems (vol. 2). milan: springer. szymkiewicz r. and gąsiorowski d. 2021. adaptive method for the solution of 1d and 2d advection– diffusion equations used in environmental engineering. j. hydroinformatics 23(6): 12901311. yang w.y., cao w., chung t.s. and morris j. 2005. applied numerical methods using matlab. a john wiley & sons. hoboken, nj. vary with the time and space of the given dimension. the finite element method descretizes only in space and the time descritization is based on the finite difference methods. hence the finite element method needs human power still now for the descritization process of time. so this is a very interesting area to do researches in the future to include the time descritization in the method. ahsan m. 2012. numerical solution of the advectiondiffusion equation using laplace transform finite analytical method. int. j. river basin manag. 10(2): 177188. aragonés l., pagán j.i., lópez i., navarrogonzález f.j. and villacampa y. 2019. galerkin's formulation of the finite elements method to obtain the depth of closure. sci. total environ. 660: 1256-1263. bajellan a.a.f. 2015. computation of the convection diffusion equation by the fourth order compact finite difference method. doctoral dissertation, izmir institute of technology, turkey. bergara a. 2011. finite difference numerical methods of partial differential equations in finance with matlab. master and banca. new york, springer. brenner s.c., scott l.r., & scott l.r. 2008. the mathematical theory of finite element methods. vol , pp 263-291. springer, new york. donea j. and huerta a. 2003. finite element methods for flow problems. john wiley & sons. 74 the core of this work was completed during the master study at hawassa university and presented to former school of mathematics and statistical science (currently department of mathematics) in partial fulfillment of the requirement for the degree of master. the authers would like to thank the department of mathematics at the university of hawassa university. this work of has been partially supported by hawassa university. references acknowledgments juliet and florence _ beef handling practices at abattoir and bucher shops_doi.pdf (p.1-17) amanuel_ study of reaction mechanisms in α + 69ga reaction at ≈10 – 50 mev_doi.pdf (p.18-27) buchale and atnafu_population dynamics and yield estimation of common carp.pdf (p.28-41) haftom et al_synthesis characterization and antibacterial activity of benzimidazole.pdf (p.42-51) kassahun and zerihun_ numerical solutions of advection diffusion equations.pdf (p.52-74) east afr. j. biophys. comput. sci. (2025), vol. 6, issue. 1, 15-25 *corresponding author: email: markonaldagm@gmail.com ,+251946526872 https://dx.doi.org/10.4314/eajbcs.v6i1.2s an ethnobotanical study of a medicinal plant justicia schimperiana (sensel) in adaba and shashemene districts west arsi zone, southern ethiopia mekdes tadesse mekonen1*, hewan demissie degu2 1ph.d. student in the department of translational agricultural science, college of biosciences and biotechnology, national cheng kong university, taiwan; department of biotechnology, college of natural science, bule hora university, ethiopia 2plant biotechnology, school of plant and horticulture sciences, college of agriculture, hawassa university, p.o. box 05, hawassa, ethiopia keywords: ethnobotany; justicia schimperiana; medicinal plant; sensel; southern ethiopia abstract justicia schimperiana is an evergreen shrub growing in the wet part of ethiopia. the plant is known by different names among the localities and is commonly termed sensel. it is usually used for medicinal purposes for various communicable and non-communicable diseases. however, the extent of the ethnobotany of this plant has not been studied well before, so the aim of this study is to assess the palaeobotanical knowledge of the sensel plant (justicia schimperiana). parallel to the sample plant collection, a total of 30 informants (21 male and 9 female) were selected to collect ethnobotanical information from two districts. among the informants, 7 key informants who are known as traditional healers were selected purposefully. ethnobotanical data were collected through semistructured interviews and group discussions were analyzed. the study indicates that the community, mainly those of low economic status and people who have failed to be healed by modern medication from their health problems, depend on an indigenous herbal remedy medication like sensel. hence, the sensel plant is used to prepare a remedy for human and animal diseases like rabies, hepatitis, skin diseases, communicable diseases, asthma, malaria, abdominal disorders, livestock diseases, and other human-related ritual problems. introduction background of the study justicia schimperiana, a member of the acanthaceae family, is also known as adhatoda schimperiana or gendarussa schimperiana. locally, it is called dhumuugaa in afan oromo, sensel or simiza in amharic, and surpa, kasha, or keteso in sidama. this fast-growing, multibranched shrub (2–3 m tall) thrives in wet montane forests, riverbanks, and village hedges at altitudes of 1300–2700 m (hedberg et al., 2006). it is widely distributed in ethiopia, kenya, and tanzania and is often used as a live fence (abebe et al., 1993). in ethiopia, the leaf decoction is traditionally consumed with local beer to treat asthma, while fresh leaves are used for contagious diseases. in eastern ethiopia, it serves as a laxative, while in northern ethiopia, alone or mixed with other east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs research article east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 15-25 16 plants, it is used for mental illness, epilepsy, eye diseases, leprosy, malaria, jaundice, rabies, gonorrhea, syphilis, measles, relapsing fever, vitiligo, gout, and febrile illnesses (abebe, 1996). in southwest ethiopia, fresh leaves are crushed and macerated in water for treating malaria and scabies (teferi, 2003). despite its medicinal importance for human and livestock diseases, indigenous knowledge about sensel is at risk due to its oral transmission, leading to knowledge loss and deterioration (mesfin, 1996). ethnobotanical studies on justicia species in the americas, asia, and africa have primarily focused on various ethnopharmacology, phytochemistry, and biological properties (sundaram and purwar, 2011). in ethiopia, most research emphasizes traditional practitioners and the historical medico-magical and/or medico-spiritual manuscripts and ancient gee'z manuscripts, overlooking the knowledge of local communities (fasil, 2005). the oral transfer of herbal knowledge, however, risks losing critical information on plant use, preparation, and medicinal applications in animal and human diseases. therefore, documentation of medicinal plants and the indigenous understanding associated with them are crucial to identify threatened medicinal plant species to present due attention to proper control and conservation (moa, 2010). therefore, this study aimed to investigate the ethnobotanical information on a medicinal plant justicia schimperiana (sensel) in adaba and shashemene districts in southern ethiopia. ethnobotanical background of justicia schimperiana ethnobotany is the scientific look at the conventional know-how and customs of a human being regarding the flora and their medical, religious, and different uses. therefore, it's far well worth explaining the conventional remedy. a traditional medicine (tm) is described as the whole of the know-how and practices whether explicable or inexplicable, used inside the diagnosis, prevention, and removal of physical, mental, and/or social imbalance (who, 1979). since time immemorial people have discovered treatments inside their habitat, and feature exceptional healing techniques relying upon the climatic, physiographic, floral, and faunal characteristics, in addition to the abnormal cultural and sociostructural typologies. in doing so, human beings have used conventional remedies to treat diverse disorders. it has integrated plant, animal, and mineral-primarily totally based medicines, and non-secular therapies, consisting of strategies and exercises, implemented alone or in combination (adewumi, 1991). traditional medicine is primarily based on accumulated practical experience and observations passed down through generations, either orally or in written form. it encompasses healing practices that have existed for centuries, often predating modern medical treatments, and continue to be utilized today without widely documented adverse effects (elujoba et al., 2005) acanthaceae is a family of dicotyledonous flowering plants comprising almost 250 genera and about 2500 species (reddy et al., 2013). most are tropical herbs, shrubs, or twining vines; a few are epiphytes. only some species are allotted in temperate areas. the 4 important facilities of distribution are indonesia and malaysia, africa, brazil, and central america. the representatives of the own circle of east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 15-25 17 relatives may be discovered in almost every habitat, inclusive of dense or open forests, in scrub lands, on moist fields and valleys, on the seacoast and in marine areas, and in swamps and as a detail of mangrove woods. justicia is the most essential genus of acanthaceae, with about six hundred species which might be discovered in pan tropical and tropical areas (correa and alcantara, 2012). in ethiopia, the shrub can most customarily be discovered in fences around homes and cultivated fields, wherein it has commonly been planted. in the wild, the plant grows at an altitude of 1250-2500 m, on mountain slopes, along roadsides, alongside rivers, in woodland and woodland edges. the plant may be discovered in plants and fruit all year-round, maximum abundantly so inside the dry duration from october until january (sebald, 1972). justicia schimperiana is shipped in excessive awareness in nearly all areas of ethiopia and different east african nations like eritrea, somalia, kenya, and tanzania. other research discovered that this inexperienced plant is one of the maximum abundant, widespread, and regenerative species in northwestern ethiopia; northern ethiopia (haile et al., 2008); southwestern ethiopia (nune, 2008); and southeastern ethiopia (moa, 2010). the plant grows in many of the ethiopian ecosystems particularly in wet montane woodland, commonly close to streams and rivers, in evergreen scrub on hill slopes, woodland clearings, espresso plantations, waste floor or planted as hedges around homesteads in dry and wet `woina dega` and wet `dega` agroclimatic zones in tigray, gondar, gojjam, ilubabor, keffa, sidamo, shoa and harerghe (tesemma, 2007). justicia schimperiana is commonly propagated through cuttings, and seedlings also can be raised from it. it is likewise self-incompatible, and a totally excessive degree of geitonogamy is discovered in this species. the pollination device is anticipated to play a chief function in figuring out plant reproductive achievement within side the face of environmental variation and shaping its sample of genetic diversity. the plant is a great fence plant, forming a herbal barrier round compounds of house, and is mainly cultivated for this purpose. in ethiopia, it does now no longer appear to be cultivated broadly for medicinal purposes (amare, 1976). chemical composition and pharmacological activities justicia schimperiana has been traditionally used for the treatment of diabetes mellitus. researchers have evaluated the hypoglycemic and antihyperglycemic activities of aqueous extract of justicia schimperiana leaves in ordinary and streptozotocin-induced diabetic mice. the result showed that aqueous extract of the plant has substantial anti-hyperglycemic activity in streptozotocin-induced diabetic mice and enhancement in glucose tolerance as well as slight hypoglycemic activity in normal mice and vindicating the old claim for its use in diabetes. in addition, justicia schimperiana contains alkaloids, phenols, and terpenoids. any of these secondary metabolites may be responsible for glucose suppression in the blood (andualem et al, 2016). it is indicated that justicia schimperiana has a hepatoprotective activity which is the ability to prevent liver damage due to the presence of hydroalcoholic in the leaf extracts. as the hydroethanolic extracts offered higher east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 15-25 18 antioxidant activity, it is possible to establish the potential application of hydroalcoholic extracts from justicia schimperiana in the development of products with antioxidant properties and demonstrate a promising pharmaceutical product. the methanol extracts of the plant also possess antioxidant activities. this justifies the traditional uses of justicia schimperiana in ethiopia for the treatment of some hepatic disorders and suggests the possible utilization of these plants as a source of new drugs (umer et al., 2010). justicia schimperiana is traditionally used for the treatment of malaria and the crude extract confirmed of the plant is endowed with antimalarial activity. jemal (2014) evaluated the anti-malarial activities of chloroform, methanol, and aqueous fractions of the leaves of this plant against plasmodium berghei in mice. consequently, the methanol fraction significantly prevented the reduction in rectal temperature in the 4-day suppressive, curative, and repository tests. thus, the high antimalarial activity observed in methanol and aqueous fraction indicates that the plant’s active constituents are semi-polar and polar. this proved that the traditional use of the plant could be a potential source of templates for the development of new anti-malarial agents (jemal et al., 2014). the leave extracts of ruta chalepensis and justicia schimperiana were the most powerful medicinal value. the plant extraction was followed by ethanol, methanol acetone, diethyl ether, and hexane by using disc diffusion and broth dilution methods (mic) against six human pathogenic bacterial strains (shigella dysentery, escherichia coli, streptococcus aeruginosa, pseudomonas aeruginosa, staphylococcus aureus, salmonella typhi, and klebsiella pneumonia). the methanol extract of j. schimperiana showed strong inhibition activity against s. dysentery and e. coli. four antibiotics were used as standard for the testing of antibacterial activity against six different human pathogens. among the antibiotics, ciprofloxin showed a maximum zone of inhibition ranging from 20-35mm followed by kanamycin, tetracycline, and chloramphenicol (habtamu et al., 2019). diarrhea is one of the leading causes of preventable death in developing countries and mainly affects children and infants. it has been reported that the leaf of justicia schimperiana is used as an antidiarrheal agent in northwest ethiopia. the 80% methanolic leaf extract of j. schimperiana was evaluated for its activity against castor oil-induced diarrhea enter polling and gastrointestinal motility in mice. the methanolic leaf extract of justicia schimperiana has an antidiarrheal activity and this supports the use of this plant in the treatment of diarrhea in traditional settings (mekonnen et al., 2018). materials and methods description of the study area this study was conducted in adaba and shashemene districts in west arsi zone oromia regional state, ethiopia. adaba is located at 335 km from the capital addis ababa; adaba district is bordered on the southwest by nensebo, on the west by dodola, on the northwest by the shabelle river which separates it from the gedeb asasa, and on the east and south by bale zone. the astronomical location is 7.00376 latitude and 39.39063 longitudes with 7o 0’ 20” n and 39o23’ 38” e cordials. its east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 15-25 19 altitude ranges from 1750 to 3400 m above sea level (west arsi zone, 2006). the 2007 national census reported the total population of the woreda was 138,717. adaba has an estimated population density of 63.8 people per square kilometre (csa, 2007). shashamane is located at a distance of 250 km south of addis ababa, the capital city of ethiopia, and 25 km north of awassa, snnprs. it is bordered to the south by snnpr, west by siraro, north by arsi negele, and east by east arsi zone. it has a latitude of 7° 12' north and a longitude of 38° 36' east. it is situated at an average altitude of 1924 m above sea level (figure 1). figure 1: map of the study area (source: researcher) the rainfall of the study area is bimodal, with the main rainy season occurring between july and september. the dry season lasts from november to february, followed by the short rainy season during march and april. from the weather records of 1994-2004, the average rainfall of adaba district was 733 1000 mm and the temperature ranges from 7-240 c. the agroecology of the shashemene district is categorized as kolla (50%), woina dega (29%), and dega (21%). shashemene district receives an annual rainfall of 700–950 mm and the minimum and maximum annual temperature of 12 °c and 27 °c, respectively. the total land coverage of the area is 76,888 ha, of which 48,975 ha is used for cropland and 7440 ha for forest land (west arsi zone, 2006). sampling research site the study area was selected based on the information obtained from the background studies and the researcher herself evident the concentration of medicinal plants in southern ethiopia. as part of the medicinal plant, justicia schimperiana is extensively distributed in high concentrations in almost all regions and particularly in the southern part of ethiopia (hedberg et al., 2006). accordingly, the researcher has made a preliminary survey in southern ethiopia specifically in the study area on the existence and distribution of the plant. the researcher has also existing knowledge about the medicinal value of the plant at the selected research sites where the plant is abundantly grown, and people use it for different treatments. therefore, due to the above justification, the researcher has identified adaba and shashemene districts as the research sites. sampling technique and sample size, data collection, data analysis a total of thirty (21 male and 9 female) informants were selected out of the two study areas, 23 (12 from adaba and 11 from shshemene) were selected purposely based on the availability of sensel around their environment as general informants. all respondents are above 40 years old. they were selected during the plant sample collection survey based on the availability of the plant on their fence, compound, and village. they were east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 15-25 20 asked to give their knowledge about the plants they were used, plant parts harvested, method of preparation for use, and other related information about the plant and its purpose. seven (7) key informants or local healers (3 from shashemene district and 4 from adaba district) were selected purposively based on the recommendation from elders of the study areas. the qualitative data were gathered through semi-structured questionnaire. thus, the surveys were carried out from january 2020 to end of april 2021(in three phases) using semistructured interviews. interview questions were determined beforehand, and some arose during the conversation to clarify the major questions in the questionnaire. both general and ethnobotanical questions were translated to the local language for conversation. before the administration of the interview, discussions were held to elaborate on the objective of the study and receive the consent of interviewees; and build on trust to share local knowledge about their experience on the justicia schimperiana plant. the information gathered from the respondents was interpreted and cross-checked and secondary related literature was also consulted. finally, a descriptive analysis was made to reconstruct the indigenous knowledge of the respondents on the plant. results according to the demographic data (table 1), the total number of respondents used to interview was 30. among these 53.3% were from the adaba district and 46.7 % were from the shashemene district. key informants were selected based on their indigenous knowledge as a traditional healer in the respective districts. accordingly, from the total number of key informants, 57.14% of the key informants were interviewed in the adaba district whereas the remaining 42.86% were interviewed in the shashemene district. table 1: demographic data of general informants, key informants, respondent’s occupation, and respondents knowledge about the plant general informants district male female total % adaba 11 5 16 53.3 shashamane 10 4 14 46.7 total 21 9 30 100 key informants adaba 3 1 4 57.14 shashamane 3 3 42.86 total 6 1 7 100 respondents’ occupation occupations local elders farmers traditional healers others in numbers 10 8 7 5 in percentage 33% 27% 23% 17% respondents knowledge about the sensel plant medicine, livestock food and fence fence cleaning and firewood consumption spiritual purpose in number 15 10 3 2 in percentage 50% 33% 10% 7% east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 15-25 21 most of the respondents were purposively selected from various occupations based on their knowledge and experience with the use of the plant in their localities. about 10(33%) of the respondents were local elders, 8(27%) were farmers and traditional healers which accounts for 7(23%) were selected as respondents followed by 5(17%) of the respondents who are religious fathers and government employee to constituted in this study areas. all of the respondents have knowledge about the plant mainly regarding the inhabitation of the sensel plant in their surroundings. as informants portrayed the plant grows both naturally and by human cultivation along their fence. the non-cultivated sensel plant usually grows in forests, shrubs and along the roadsides. according to the informants, they acquired the indigenous knowledge from their families who were traditional healers and informally adopted it from the community as habitual action against common diseases and for other activities. table 1 shows that fifteen (50%) of the respondents including key informants of the study area have knowledge of the use of the sensel plant for various purposes like medicinal, livestock food and fence. about ten (33%) of the respondents have mentioned that the plant is used for fencing purposes. about three (10%) portrayed the sensel plant also used for cleaning clay pots and for firewood consumption in the study areas. other respondents account for two (7%) of the respondents who have suggested that the plant is used for spiritual purposes. the sensel plant widely grows in the study area both in human-made and natural ways. the plant is used by society for medicinal value in the very rear situation. it is commonly used for fencing purposes along the living quarter of the locality due to the evergreen, jungle and dense characteristics, and drought resistance nature of the plant (figure 2). figure 2: justicia schimperiana (sensel) the indigenous knowledge of the study area indicates that the plant is used for medicinal value to humans and animals. from the part of the plant, the leave parts are used for the extraction and remedy of various health disorders. accordingly, the following illness is identified that the traditional healers in the study area use the plant for treatment (table 2). east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 15-25 22 table 2: traditional importance of sensel (justicia schimperiana) plant in the society purpose of the plant part of the plant used preparation, combination, and remedy ways of treatment hepatitis fresh leave squeezed and mixed with local beer taking a cup of coffee bronchial asthma dried leave powdered and mixed with local beer taking half of a coffee cup contagious disease fresh leave chopped and diluted with water taking half of a coffee cup abdominal illness fresh leave squeezed and mixed with powder of vernonia amygdalina (grawa) and s.oxyacantha (tenadam) take a coffee cup with many volumes of water daily until cured dermal disease fresh leave crushed and socked with water washing the affected area rabies fresh leave crushed with calabash (qel) taking half of a coffee cup with fresh milk livestock disease leave squeezed, mixed with garlic and soaked with water half of a litter is given to the cattle spiritual leave soaked with water sprinkled at the home of the household and local drink house cleaning leave boiled with various herbs washing home utensils and local jars. washing early mothers who gave birth. besides treatment of infectious diseases, the leaves are used by local people for protection and treatment of communicable sexually transmitted diseases. the traditional healer also elicited that the remedy is also used under normal conditions to protect against the risk of contagious diseases mainly transmitted through sexual intercourse. a dermal disease called scabies which is caused due to an insect bite and leprosy due to bacterial infection is treated and cured by herbal medicine made of sensel. the dose of the medicine is not determined rather it is based on the amount of the affected area of the dermis and applied until the skin regains its natural look. informants of the study areas portrayed that the sensel plant is highly effective to treat rabies disease among domestic animals which are caused by viral infection due to the bite of infected animals. the plant is used both for protective and curative purposes. when there is a suspicion of rabies infection among the localities, people used to provide the remedy plant to the domestic animals because it is believed that sensel plant has anti-rabies treatment. however, if there is a certain condition of rabies infection among the domestic animals, the herbal medicine made of sensel is given to the affected animals within three days. the informants suggested that fresh milk has the role of reducing the acidic nature and the unpleasant smell of the remedy. discussion according to the informants, the plant is also used to treat cattle diseases for instance wounds and swelling appear inside the mouth of livestock. sensel plant had also been used for the ritual aspects among the society for a long period of time. as respondents have evidenced that the society had been perceived and suggested that the sensel plant has the power of protection from the evil spirit like a sprit against the wealth and healthy wellbeing of peoples. east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 15-25 23 this has been practiced in two ways; the leave of sensel plant crushed and mixed with water then sprinkled in the living home and traditional alcohol drink houses like ‘tela bet’ and ‘tej bet’. the second way of protecting from the bad spirit is by planting the sensel plant along the living quarters as fencing. however, such activities are declining recently due to the propagation of religious teaching and considering backward practices among the community. the plant is used for cleaning kitchen materials (utensils) and maintaining the good health of the woman’s skin. the big clay jar (insira) which is used for fermentation and preparation of local bear (tela) is cleaned using the leave of sensel plant. according to informants, the plant keeps the flavor, a test of the drink and neatness of the jar as well. when a woman gives birth on the fifth day of her birth leave and rest, traditionally the baby mother showering event called sheneni is hosted. for such events, various medicinal herbs were collected and boiled with water. thus, the sunset plant leave is highly selected and used as medicinal leave along with other herbs. because the plant is believed that it has both spiritual roles to protect the mother against evil spirit and regains the skin and exhausted body of the baby mother. generally, according to the indigenous knowledge of the study area, the sensel plant has been used for medication and nonmedication purposes. however, the dosage of the remedy is mostly determined by the physical maturity and age of the user rather than the chronic level of the disease. thus, to manage the over dosage effect and associated contradiction and effect of the medication the traditional healer used to give milk and coffee along with the medication. according to the informants’ local knowledge in the study area, the justicia schimperiana plant was traditionally used for the treatments of different diseases such as hepatitis b (ye wef beshita), bronchial asthma, contagious diseases, abdominal illness, dermal disease, rabies, livestock disease. these findings were in line with other studies which were done before by different researchers in separate study areas in ethiopia. subsequently, justicia schimperiana is used in the treatment of various ailments such as asthma and other inflammatory situations, excessive pellagra, and constipation (yinebeb, 2008); gonorrhoea, rabies (tolera, 2017). hepatitis b treatment (haile et al., 2008), for diarrhoea treatment and also reported that the plant is used in the treatment of livestock ailment (blackleg) and internal parasites (teklehaymanot and giday, 2007). in addition, justicia schimperiana is used to treat malaria and gonorrhoea in southern ethiopia also indicating that the leaf and root of justicia schimperiana are used in the treatment of rabies and coccidiosis in western ethiopia (tadesse and dereje, 2015). justicia schimperiana is used to treat skin lesions in shinasha, agew-awi and amhara peoples in northwest ethiopia (giday et al., 2007). furthermore, its fresh root is used to treat diseases in emergencies; the fresh leaf of justicia schimperiana is used to treat rabies in fiche district, central ethiopia (abiyu, 2014). conclusion & recommendations justicia schimperiana (sensel) is an evergreen plant and grows in different parts of ethiopia mostly as an unmanaged and managed plant. in most parts of the country, people use the plant for medicinal purposes and to fence their compounds. based on the finding of this study, the community mainly those who are of low east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 15-25 24 economic status and people who have failed to be healed by modern medication from their health problems re-laid on an indigenous herbal remedy medication like sensel. accordingly, the sensel plant is used to prepare a remedy for human and animal diseases like rabies, hepatitis, skin diseases, communicable diseases, asthma, malaria, abdominal illness / disorders, livestock diseases, and other human-related spiritual problems. it would be important to save the plant populations in different regions to limit population decline caused by large-scale environmental catastrophes. the species or at least a large part of its genetic diversity may be lost soon due to its medicinal and other uses, urbanization, and its consequent exploitation if proper conservation measures are not adopted. the government and the stakeholders in the respective field should give due consideration to the ethnobotanical studies. thus, indigenous knowledge on medicinal plants in general and sensel plants in particular should be widely investigated and documented at various levels from the locality to higher research institutions in the country. to conserve the plant and to avoid the risk of endangerment of the plant in future, the sensel plant should be conserved or planted along with other medicinal plants in the home garden of households, species, and genetic conservation sites like the institute of national biodiversity. under the current launched national green environment campaign and indigenous nursery afforestation, medicinal plants like sensel should also be planted along with the nurseries of trees. consequently, it sustains the diversity of the sensel species and maintains the natural aspects of the ecosystem. funding statement this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. data availability statement the data supporting the conclusion of this article are included within the article. any queries regarding this data may be directed to the corresponding author. declaration of interest the authors declare no conflict of interest. acknowledgements the author would like to forward heartfelt gratitude to the study subjects for their willingness to participate in our study. i use this opportunity to thank hawassa university, the school of plant and horticulture sciences, department of biotechnology for their material assistance and encouragement. references abebe d. 1996. the role of herbal remedies and the approaches towards their development, in proceedings of the workshop on development and utilization of herbal remedies in ethiopia, nazareth, ethiopia, 111:29. abebe d. and ayehu a. 1993. medicinal plants and enigmatic health practices of northern ethiopia b. s. p. e.: addis ababa, ethiopia. abiyu enyew, zemede asfaw, ensermu kelbessa and raja nagappan. 2014. ethnobotanical study of traditional medicinal plants in and around fiche district, central ethiopia. curr. res. j. biol. sci. 6(4): 154-167 adewumi c. o. 1991. plant molluscicides. potentials of aridan. tetrapleaura tetraptera for schistosomiasis control in nigeria. sci. total environ. 102: 21-23. amare g. 1976. some common medicinal and poisonous plants used in ethiopia folk medicine. addis ababa university, pp.3-63. east afr. j. biophys. comput. sci. 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(2024), vol. 5, issue. 2, 13-28 effect of land use activities on water quality and vegetation cover change in nsooba lubigi wetland system, kampala city charles k.twesigye1*, kennedy igunga1 and ritah nakayinga1 1 department of biological sciences, faculty of science, kyambogo university, p.o. box 1, kyambogo, kampala, uganda keywords: agriculture; built environment; public health; pollution; wetland abstract an assessment of the effect of land use activities on water quality and vegetation cover change in nsooba lubingi wetland system in kampala city was conducted between july and october 2020. in order to achieve the set objectives, twelve locations were selected from the nsooba lubingi catchment. the physico-chemical characteristics of water along the catchment area were determined by standard analytical methods. the average values for total dissolved solids across all the land-use types of wetland, built up areas and agriculture were lower than the national standard (750 mg/l). a similar pattern of the land-use was observed for the parameters total phosphorous, biological oxygen demand, chemical oxygen demand, total suspended solids and total organic carbon, where the observed average values were all below the national standards of 10 mg/l, 50mg/l, 70mg/l, 50mg/l and 50mg/l, respectively. the total nitrogen average value for built-up areas (11.27 mg/l) was higher than the national standard of 10 mg/l while the remaining land use types of wetland (8.05mg/l) and agriculture (5.96mg/l) were below that of the recommended standard. gis and remote sensing techniques were used to analyze highresolution satellite imagery captured during 1998, 2008 and 2018. wetland coverage declined by approximately 5 hectares (47.2% to 14.58%) from 1998 to 2018. although most of the measured parameters were below the national standard specified by the uganda national environmental management authority apart from total nitrogen for built-up areas, there is need for close monitoring of the water quality in nsooba lubingi catchment to ensure public health safety. the increased built-up environment in the nsooba lubigi wetland affects ecosystems services of the wetland. the buffer zones for flood control and sewage treatment have been turned into built-up environment. the results from this study suggest a need to protect the nsooba lubingi catchment for its important ecosystems services of flood control and sewage treatment. introduction the world's growth metrics have been impacted by unchecked expansion in a variety of human undertakings, including industrial, transportation, agricultural, and urbanization (gavrilescu et al. 2015 and mishra et al., 2023). globally, water quality deprivation is one of the main persistent, and greatly observable signs of anthropogenic impacts. surface water bodies east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx *corresponding author: email: twesigyeck@yahoo.com +256-782353775 https://dx.doi.org/10.4314/eajbcs.v5i2.2s research article east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 14 such as reservoirs, river streams and lakes are enormously vulnerable to primary discharges of solid and liquid waste. extremely dilute water bodies, specifically in headwater regions are vulnerable to impacts caused by atmospheric deposition (acid rain) (sasakova et al., 2018). in developing countries, the changes in land use are directly and indirectly related to pollution challenges that include sewage, insecticides and pesticides, greatly contaminated water quality, principally near intensive agricultural areas and urban industrial centers (wang et al., 2015). this alters the ecological landscape, severe strain from anthropogenic encroachment as well as consistent land filling activities for reclamation, water drainage for agriculture and livestock farming, human settlements, clay and sand extraction, brick making, harvesting of papyrus, municipal and industrial waste discharges, unsuitable and illegal solid waste disposal (peters et al., 205, kayima et al., 2018). in the natural ecosystem, heavy metal concentrations differ, human activities alter the distributions and natural cycles of metals creating an unbalanced ratio in the metal cycle leading to accumulation (edokpayi et al., 2018). many studies of watershed microbiology focus largely on the detection of indicator microbes such as e. coli, enterococci, salmonella and coliform bacteria and how these might indicate potential risks to human health and environment. hawumba (2017) indicated that; in uganda, the leading causes of water quality impairment is high nutrient (phosphorus and nitrogen) discharge to the ground and surface water bodies. the same author further added that, whereas nitrogen is of principal significance in affecting and preventing eutrophication in marine environments, phosphorous is the restraining nutrient in freshwater (or non-saline) ecosystems. according to ding et al., (2015), studying the correlation among water quality and land use supports to ascertain primary stresses to water quality which are predetermined for efficient water resource and quality control since they can be used to target key land use regions and to incorporate pertinent methods to curtail contamination discharges. similar studies on land use have indicated its substantial impacts on water quality (twesigye et al.,2011). deforestation, urbanization and agriculture mostly alter land topography and characteristics, surface runoff volume, upsurge algal production, generate contamination and reduce concentrations of dissolved oxygen in water resources. according to wang et al. (2015), vegetation cover is an indicator that assesses terrestrial environmental surroundings. minor alterations of vegetation structures of the landscape inhibit ecological processes. the increasing rates of land-use change over natural habitats like wetlands, lakes, rivers have resulted into the conversion of the natural environment for agriculture, sand mining, fishing and urbanization. any deterioration of the natural vegetation raises the quantity levels of particulate matter in water, and consequently can directly and indirectly affect water quality (fierro et al., 2017). according to sebhatleab (2014), land use change has triggered the decline in both soil physicochemical and biological properties depending on the classification levels across the landscape and soil profile. constant exposure of top soil can attribute to long-term intensified vegetation deprivation and start a process of land pollution (marinho et al., 2016). the east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 15 surface water flow from the upstream, as well as the populous slums of kawaala, kyebando, kalerwe, bwaise, kanyanya, nansana and namungoona (karabo, 2017). due to insufficient environmental policies like development of the buffer zone to protect drainage system, nsooba lubigi drainage system has and will continuously receive the initial and direct trickle-down effect of the visually and severely contaminated wastewater from the up-stream storm water draining to the channel as well as the lubigi sewage treatment plant. additionally, nsooba lubigi drainage system has continuously been under serious pressure emanating from human actions and encroachment including unplanned land filling for reclamation, water drainage for agriculture, human settlements and livestock farming, use of agricultural pesticides in management of crops, sand and clay mining, brick making, the harvesting of papyrus for handcrafts, inappropriate solid waste disposal, municipal and industrial effluent disposal and other forms of discharges have led to pollution and contamination of the drainage system thus being a haphazard to the environment and surrounding community. the area was selected as an ideal site because of the urbanization levels (construction of northern by-road), crowded settlements and the apparent poor sanitation and management of waste water. further, nsooba slaughter house also discharges solid and waste water into lubigi wetland, creating severely contaminated wastewater from the upstream nsooba lubigi water drainage stream and the lubigi sewage treatment plant. correlation between land use activities and its impact on soils involves studying the drivers of the variations in soil structure and help in illustrating good management processes to prevent desertification and attain conservation goals. limited studies have been conducted to study the overall interactions between land use and water quality. the consequences of anthropogenic activities on water quality, soils, and vegetation cover are severe and call for sustainable management. this study examines the relationship between land use and water quality to determine the microbial and physic chemical attributes of the water, soils integrity, as well as the vegetation cover along nsooba lubigi drainage system. this study,therefore, explores the effect of land use activities on water quality, soil and vegetation cover on nsooba lubigi drainage system. materials and methods study area the study area lies within nsooba lubigi drainage system, stretching from bukoto hills, the origin of nsooba lubigi to lubigi wetland in namungona. it is located between 0° 21’n latitude and 32° 35’e longitude, in kawempe division, kampala city. the discharge from the surrounding environment to nsooba lubigi drainage system is about 220,000 m3/day and originates from the daily human activities, industrial and municipal effluent, automotive and mechanical discharge, rainwater run-off, surface and subeast afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 16 figure 1: study sites in nsooba lubigi drainage system, kampala city data collection tools and methods land use land cover change activities landsat-5 tm, landsat-8, and sentinel 2 images with a spatial resolution of 30m and 10m for 3 years (2018, 2008, and 1998) were downloaded from an open-source at no cost. these were used for the spatial analysis of land use activities and vegetation cover change in nsooba lubigi. table 1: data specifications satellite data mm/dd/yy path and row band resolution source landsat 5 (tm) 08/07th/1998 172,059 3,4,5 30m x 30m usgs landsat 7 (etm+) 09/14th/2008 172,059 3,4,5 30m x 30m usgs landsat 8 (oli/tir) 10/07th/2018 172,059 3,4,5 30m x 30m usgs a hand held gps receiver was used for ground verification in evaluating the five land use/ cover classes as indicated in table 2. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 17 table 2: land use land cover (lulc) classification by anderson method land use/cover classes description agriculture subsistence farming: mixed farming characterized by crops grown for survival small scale farming small scale farming: mixed farming, single and multi farming, dry and irrigated farming bare land land that is productive and unproductive with no developments activities going on wetlands seasonal and permanent wetlands, swamps, bog built-up areas settlements like residentials, commercials, non-residentials, roads as supervised classification was performed at the study area, each class was calculated while considering the pixel counts and total site (table 2). thus, categorizations were made based on area coverage and presented in both hectares and percentage. the five classes included forestry, grassland, wetlands, settlement, and small scale farming. percentages of classes based on these results portrayed land use/land cover events seen in the study area during 1998, 2008, and 2018 respectively. sampling strategy water and soil samples were collected from the field for further analysis. a minimum of 48 water samples and 36 soil samples were gathered from 11 sites along nsooba lubigi drainage system. the sites were selected due to the high anthropogenic activities (urbanization, slaughterhouse, industries and road construction) carried out within the wetland area. a minimum of 4 sampling at each sampling site were collected in duran. parameters for analysis included ph, ec, tss, tn, tp, total coliform and e. coli, bod and cod. these constitute the major parameters in measuring the degree of contamination of a water body (chapman, 1992; longe and omole 2008). all the samples were preserved at 4oc using a sampling cooler box and transported to the laboratory for analysis. sampling was done between 08.00 am and 05.00 pm, the time of peak activities at the nsooba lubigi drainage system in july 2020 and october 2020. during sample collection, sampling containers were rinsed twice with sampled water and, labeled and then taken to the ministry of water and environment laboratory in entebbe, stored in the refrigerator while maintaining a temperature of 4°c prior to analysis. water pollutants water samples were collected between july 2020 and october 2020 in two sets to ensure that the results obtained are more representative. each set consisted of 24 samples totaling to 48 samples. analytical procedures and measurement in order to assess the effect of land use activities on quality of water and vegetation cover of nsoobalubigi drainage system, physicochemical properties and nutrients loads from upstream and downstream of the kalerwe abattoir discharge area were evaluated. the physico-chemical characteristics were determined by the american public health east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 18 association (apha) standard analytical methods of water analysis. hach standard method was used to determine nutrients concentrations by using a dr 1900 spectrophotometer and a drb 200 digester as defined in the hach procedure manual for chemical and physical water quality. total suspended solids were analyzed using a gravimetric method. the galen kamp oven was used for drying at 105°c and a mettlor toledo weighing scale was used for weighing. chemical oxygen demand was determined by a standard hach procedure using a dr 6000 spectrophotometer and drb 200 digester as described in the hach procedure manual. a volume of 2mls of the sample were put in the cod vial and digested at 150 °c for 2hrs. the vials were allowed to cool and cod was read. bod was analyzed using a bod5 day test kit. this was used for digestion and monitoring oxygen changes. determination of ph & electrical conductivity ph was photometrically analyzed using a thermo scientific orion star 3 machine whereas electrical conductivity was analyzed using an orion star a 222 conductivity meter. determination of vegetation cover change this was determined using landsat8 and sentinel 2. landsat enabled the acquisition of old satellite images of 2008 and 1998, whereas sentinel facilitated the acquisition of satellite image of 2018. data analysis to compare the parameters across land use types, the data were subjected to a nonparametric test known as kruskal-wallis h-test, because it is more robust and requires smaller samples sizes. the test compares medians among k independent groups (k > 2) and is formulated based on ranks rather than actual observations (daniel, 1990). the test is generally robust to departure from normality and homoscedasticity and is less sensitive to outliers. kruskal-wallis h-test only indicates that more than two groups are significantly different. it cannot show which specific groups of the independent parameters are statistically different from each other. dunn test was used to determine which land use types were statistically significantly different from each other. fisher’s exact test was used were the data was categorical in nature and therefore difficult to compute the median. image acquisition re-classification process and change detection analysis of various land-use land-cover classes were performed by three landsat satellite images of 5 tm, landsat 7 etm+ and landsat 8 oli/tir all acquired from path 172 and row 059 as indicated in table1. the satellite imagery data was downloaded from the united states geological survey website (usgs) (ftp://ftp.glcf.umd.edu/glcf/landsat/wrs2 and https://earthexplorer.usgs.gov/). after downloading, the images were all georeferenced to the wgs 84 datum with the utm zone 36n of the coordinate system. all satellite data were analyzed by assigning per-pixel signatures and segregating the land uses to 5 classes based on different landscape elements. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 19 eight out of the nine physicochemical parameters were positively skewed (skewness> 2.0) signifying the presence of large outliers. these values for the parameters ec, tds, tp, tn, bod, cod, tss and toc are 2.563, 2.700, 2.731, 2.996, 4.400, 6.808, 2.412 and 2.867 respectively. this implied that the median was preferred to the mean as the measure of central tendency of the data and for comparison to the national standards. the ph value of 0.966 was negatively skewed, signifying accurate correlation. according to table 3, the ec values for wetland (537.5 µs/cm), built-up areas (472.5 µs/cm) and agriculture (272.50 µs/cm) remained below the recommended threshold of 1000 µs/cm. the average values for tds across all the land-use types of wetland, built up areas and agriculture (309.00 mg/l, 352.00 mg/l and 155.00 mg/l respectively) were lower than the national standard (750 mg/l). a similar pattern of landuse types of wetland, built up areas and agriculture was observed for the parameters tp (0.84mg/l, 0.82 mg/l and 0.53 mg/l respectively), bod (5.75 mg/l, 14.00 mg/l and 8.75 mg/l respectively), cod (41.00 mg/l,49.50mg/l and 42.00 mg/l respectively), tss (25.00 mg/l, 42.00 mg/l and 10.00 mg/l respectively) and toc (16.70 mg/l, 20.50 mg/l and 5.65 mg/l respectively), where the observed average values were all below the national standards of 10mg/l, 50mg/l, 70mg/l, 50mg/l and 50mg/l respectively. for tn, the average value for built-up areas (11.27 mg/l) was higher than the national standard of 10 mg/l while the remaining land use types of wetland (8.05mg/l) and agriculture (5.96mg/l) were below that of the recommended standard. the delineated classes were: agriculture, bare land, wetland and built up areas (table 2). for each of these, a designated land use/ cover category was assigned training samples by defining polygons within each sites, and signatures files created for the particular land use/ cover categories downloaded from the satellite imagery taken by using pixels enclosed by polygons. the unsupervised classification was performed using the iso clustering classification method which was followed by ground-trothing to guide in the performance of the maximum supervised classification for accuracy assessment. all classification processes were executed using arcgis 10.2 as explained in the subsequent paragraphs. results impact of human activity on the water quality the results for the effect of land use activities on physico-chemical composition of water quality are presented in table 3 and shows a significant correlation between land use activities and physico-chemical composition of water. according to table 3, the kruskal-wallis test showed p values of less than 0.05 for ec (0.007), tds (0.022), ph (0.022), tn (0.007), bod (0.000), tss (0.003) and toc (0.010), indicating that they are significantly affected by luas. on the contrary, no significant correlation was found between land use activities and tp and cod. the p value was greater than 0.05 with tp recording a p value of 0.317 and cod with 0.203.the results from descriptive statistics indicate that the data from east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 20 table 3: descriptive summary statistics and test for equality of medians for physicchemical parameters of water quality by land use parameter land use land cover no. of obs. (n) median (homogenous groups**) kruskal-wallis test* overall skewness national standard for waste water discharge, nema electrical conductivity (µs/cm) wetland 8 537.50a h = 9.838 p = 0.007 2.563 1000 (µs/cm) built up areas 36 472.50a agriculture 4 272.50b total dissolved solids (mg/l) wetland 8 309.00a h = 7.612 p = 0.022 2.700 750 (mg/l) built up areas 36 352.00a agriculture 4 155.00b ph wetland 8 7.30a h = 7.245 p = 0.027 0.966 5.0-8.5 built up areas 36 7.20b agriculture 4 7.45a total phosphorus (tp) (mg/l) wetland 8 0.84a h = 2.298 p = 0.317 2.731 5 (mg/l) built up areas 36 0.82a agriculture 4 0.53a total nitrogen (tn) (mg/l) wetland 8 8.05b h = 9.895 p = 0.007 2.996 10(mg/l) built up areas 36 11.27a agriculture 4 5.96b bod (mg/l) wetland 8 5.75b h = 16.666 p = 0.000 4.400 50 (mg/l) built up areas 36 14.00a agriculture 4 8.75b cod (mg/l) wetland 8 41.00a h = 3.185 p = 0.203 6.808 70 (mg/l) built up areas 36 49.50a agriculture 4 42.00a tss (mg/l) wetland 8 25.00a h = 11.896 p = 0.003 2.412 50 (mg/l) built up areas 36 42.00a agriculture 4 10.00b toc (mg/l) wetland 8 16.70a h = 9.126 p = 0.010 2.867 50 (mg/l) built up areas 36 20.50a agriculture 4 5.65b * national environment (standards for discharge of effluent into water or land) regulations, 2020. the effect of land use activities on the vegetation cover in nsooba lubigi drainage system the results for the effect of land use activities on the vegetation cover for the years 1998, 2008 and 2018 are shown in table 6.. table 4: land use land cover change from 1998 to 2018 year 1998 2008 2018 percentage change (%)land use land cover area (ha) % area (ha) % area (ha) % wetlands 6.93 47.21 4.05 27.59 2.14 14.58 -32.63 agriculture 2.06 14.03 4.55 31 4.47 30.45 16.42 bare land 2.13 14.51 1.05 7.15 1.04 7.08 -7.43 built up areas 3.56 24.25 5.03 34.26 7.03 47.89 23.64 total 14.68 100 14.68 100 14.68 100 0 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 21 the vegetation cover change from 1998 to 2018 was investigated for the four land use classes namely; wetlands, agricultural activities, bare land and built-up areas. according to results from table 6 wetlands gradually declined from 47.21% in 1998 to 27.59% in 2008 and 14.58% in 2018. similarly, results for bare land showed 24.5% in 1998, and drastically dropped to 7.15% in 2008 and with no significant change (7.08) in 2018. seemingly, there was gradual increase in agriculture and built-up areas by 14.03% in 1998 to 31% in 2018 and slowed growth of 30.45% in 2018; and 24.25% in 1998 to 34.26% in 2008 and 47.89% in 2018. the increase in built-up could have resulted into reduced agricultural activities. the land use/land cover changes and vegetation cover for the years 1998, 2008 and 2018 are shown in figure 2. lulc types such as agriculture and built-up areas have shown a notable increase for the last two decades (from 1998-2018). land use land cover, a, b, c in1998, 2008,2018 table 4 shows that, the total land area of the study area was 14.68ha with a variation in land use land cover change of the study area. the dominant land use type was wetlands with an area of 6.93ha (47.21%), followed by built up areas at 3.56ha (24.25%). both agriculture and bare land showed minimal changes having 2.14ha (15.51%) 2,23ha (14.03%) of the land use land cover respectively. the analysis indicated that the surrounding environment within nsooba lubigi drainage system in 2008 shows an increase in built up areas 5.03ha (34.26%) and agriculture 4.55ha (31%), these are the major anthropogenic activities that result to contamination of water quality and degradation of the nsooba lubigi wetland. there was a deliberately declined to 4.05ha (27.3%) as well as a significant decline in bare land to 1.05ha (7.15%) resulting from urbanization of the city centre. it was observed that in 2018 the built up areas consistently increased to 7.03ha (47.89%), followed by 4.5ha (30%) of the total land use and the natural vegetation cover especially wetlands to 2.14ha (14.6%) and bare land at 1.03ha (7.08%) respectively. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 22 figure 2. land use/land cover changes and vegetation cover current land uses and activities. the previous style of land use prevailed on both sides of the nsooba lubigi drainage system in the form of road structures, communication networks, settlements (planned and unplanned), and farmlands. evidence shows that the land and vegetation cover has deliberately changed compared to the past years. the nsooba lubigi drainage system has been seriously affected by mainly human activities evidenced by the on-going developments of the multitrillion road construction of the kampalaentebbe express way for easy accessibility to the entebbe international airport which has greatly affected the natural vegetation cover thereby endangering the species diversity within the study area. the physico-chemical parameters that were analyzed in water include, electrical conductivity, total dissolved solids, ph, total land use land cover change the high levels of built up areas at 23.64% and agriculture to 16.43% of the total percentage land use change between 2018 and 1998 meant intensive pressure is on the natural resources especially the wetlands thereby altering the water quality levels to -32.63% between 2018 and 1998, leading to expansion of urban agriculture along and on marginal lands as well as encroachment into protected nsooba lubigi wetland. discussion while determining the impact of land use activities on water quality and vegetation cover along the nsooba lubigi drainage system, it was noticed that there are various activities and variations in past land use as compared to the east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 23 nitrogen, total phosphorous, bod, cod total suspended solids and total organic carbon. these were selected because they bring about severe pollution and eutrophication if not controlled or regulated which subsequently impacts on the receiving ecosystem. electrical conductivity and total dissolved solids contribute to an ion influx which consequently increase the saltiness of the water. this makes it hard for the water born species to survive. ph, on the other hand increases the alkalinity or acidity of the water hence affecting the aquatic life since they have specific ph in which they survive. total nitrogen and total phosphorous are nutrients that bring about excessive growth of the algae and the other green plants in the water. this overtime inhibits direct light penetration into the water and also inhibits atmospheric re-oxygenation of the water which consequently leads to suffocation of the fish and other water borne species. further, land use activities in the study area range from agriculture which includes animal husbandry, horticulture, floriculture in the lubigi wetland, road construction, settlement both planned and unplanned. construction of northern bypass has attracted more development and population increase, this later led to creation of slums in the wetlands for example bwaise and kalerwe. national water and sewerage cooperation has also constructed a sewage treatment plant which encroached on the vegetation cover of lubigi wetland. all these land use activities have led to degradation of the wetland and loss of vegetation cover. the effect of land use activities on the physico-chemical properties of water figure 2 presents the median (homogenous groups**) of ec, tds, ph, tp, tn, bod, cod, tss and toc parameter values for the land use activities. figure 2 revealed that ec and tds were significantly impacted by land use activities while cod, tts and toc were moderately impacted. on the contrary, ph, tp, tn and bod were minimally impacted by land use activities. further, wetlands and built-up areas presented the highest significant impact on water quality, specifically ec and tds, while agriculture presented the lowest impact on water quality and this could have been attributed to the low farming activities carried out in the sampling areas. despite, the substantial effect of luas on the water quality, all the ec, tds, ph, tp, tn, bod, cod, tss and toc parameter values for wetland, built-up areas and agriculture activities were below the national standard for wastewater discharge set by national environmental management authority, 2020. this indicates that the results from wetlands, built-up areas and agricultural areas have minimal impact on the water quality. the agriculture activity recorded the lowest ec compared to built-up areas, which further increased significantly in the wetlands. similar trends were obtained by wachu (2018) who presented that ec is highest in urban sites compared to cultivated areas and forested areas. the studies concluded that high ec concentrations in wetlands is due to the increased input of ions from industrial effluents including car garages in masanafu and slaughterhouse in kalerwe and domestic wastewater. this conquers with the findings attributed by ochuka et al. (2019); who stated east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 24 moderate concentrations. this is also supported by moderate concentrations in toc from both the wetland and built-up area activities. this similar trend was also observed in the study conducted by özdemir et al. (2022)who indicated that wastes from agricultural and tourism activities in the field of study could affect nitrogen and its derivatives. built-up areas presented the highest tss and this could be attributed to poor waste management practices through littering and discharge of unhealthy effluent from both domestic and industrial activities. this is in agreement with the studies conducted by grimm et al. (2005) and shafie et al. (2017) who highlighted that bare soil at building sites has frequently resulted in large sediment inputs to the drainage streams through rainfall runoff events. the studies further indicated that the extent of fine particulate was generally higher in drainage streams around residential areas. other physico-chemical parameters including bod, cod tss and toc were moderately high though below the national standard, as observed within the sampling areas. this clearly shows that the high values could be attributed to the undigested materials and animal solid waste released from the nsooba slaughterhouse. it therefore implies that there is need for huge amount of oxygen to synthesize all of these organic materials into co2 and water, which in turn, cause high concentrations of cod and bod within the study area which could clarify on the linear correlation between solids, cod and bod. this is in line with hawumba (2017) who stated that, the subsequent highly concentrated discharge further adversely affects the water quality of nsooba channel as detected by the increase in cod and microbial overload, that anthropogenic activities such as application of agro-chemicals and waste disposal are associated to higher ec in built-up areas. in regard to tds, the concentrations from wetlands, built-up areas and agriculture were attributed to different minerals dissolved in water which include potassium, sodium, magnesium, bicarbonates, these can be connected to numerous other compounds which can be water contaminants as well. however, the results of this study differs from recent studies conducted earlier within the drainage system by hawumba (2017) and ochuka et al. (2019) who stated that increased concentration of tds results in noxiousness through heightened salinity and change in the ionic composition, influencing water taste, odour, colour and hardness. water with tds less than 600 mg/l is considered pleasant; nevertheless, extremely low tds reduces the flavor of drinking water. the average values of ph obtained under the three land uses fell within the acceptable range of the national standard (5.0-8.5), signifying that land-use did not impact the water ph. total phosphorus (tp) had negligible impact on the water quality, since the activities indicated very low quality characteristics in comparison to the national standard. this could have been attributed to the low bod levels that are recognized to favor phosphorus discharge to the freshwater ecosystem (shafie et al., 2017). it was observed that total nitrogen (tn) is moderately higher in all the 3 activities (though below the national standard). large increases in organic matter from wetland areas and built-up areas (domestic household wastewater, sewage, detergent waste, etc.) areas might have led to an increase in the factors affecting east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 25 revealing of significant nutrient quantities. the sedimentation of some suspended solids, and the mineralization of the organic loads as the water flows away from the discharge points, should partially describe the reduction in cod linked to what other researchers have studied. the effect of land use activities on the vegetation cover from table 4 it was observed that built-up areas and agriculture are the activities with the lowest stability as they are developing activities in the drainage system. this means that the transitions of wetlands and bare lands types are oriented towards urbanization and developing farming activities. the percentage changes for wetlands, agriculture, bare land and built-up areas between 1998 and 2018 were observed to be 32.63%, 16.42%, -7.43% and 23.64% respectively as shown in table 4. further, it was observed that nsooba lubigi drainage system has been subjected to a gradual process of reclamation and presently experiences some of the most dangerous threats and pressures, especially on the wetlands. the sites around the drainage system, including nsooba channel and lubigi wetland are observed as major sites for urbanization due to their proximity to the city center and industrial district. the land use land cover (lulc) results showed that nsooba lubigi drainage system was under several anthropogenic uses including industrialization, increased agriculture, road construction among others has increased the rate of loss of vegetation cover. this is agreement with twesigye et al. (2011) who stated that increased development such as urbanization and industrialization, and other anthropogenic practices have led to the decline in vegetation cover and its loss. kayima et al. (2018) also presented that rapid urbanization coupled with increasing population growth are one of the major driving factors of land use along nsooba lubigi drainage system. this proportionately relates to ding et al. (2015) who elaborated that, in most urbanized areas, land use largely contributes to nitrogen and phosphorus emanating from point source and non-point source pollutants. ribolzi et al. (2011 found that most urban households are the common point source to pollution in waste water contamination, these contain pathogens which harbor low dissolved oxygen conditions in ground water supply leading to high metal concentration in the wetlands and other aquatic plant life. urbanization has additionally stretched to water-resistant areas larger volumes of runoff. impervious rainfall runoff drains all types of pollutants including point and non-point source pollutants into rivers, which intensifies nutrients concentrations into surface waters. the strategic location of nsooba lubigi drainage system means that it offers an exclusive and significant set of amenities to the residents within bukoto, kyebando, bwaise and kawempe among others. it serves as a buffer through which much of kawempe division's and part of kampala industrial and domestic effluents pass before being discharged into river mayanja which eventually drains into river kafu. partially treated sewage from nwsc lubigi treatment plant is mixed with the untreated wastewater present in the nsooba channel before entering the lubigi wetland. the current rise in settlements around nsooba lubigi drainage system especially in the areas of bwaise, kalerwe, kyebando and makerere east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 26 among others is largely due to the high demand for affordable accommodation by people who work in the motor vehicle garages, kalerwe market and other markets around, petrol station fuel attendants and small companies located within kawempe division. this is in line with zhang et al. (2011), who stated that macroeconomic activities such as industrialization and other businesses, contributing to the growth of gdp often require large areas also contribute to the transition of forest/shrub land/grassland into buildup areas. these results are in agreement with omagor and barasa (2018) who reported that the wetland extent was narrowing at a high rate due to settlements. similar trends in the degradation of wetlands in kampala city have been reported by warsame et al. (2022) and karabo (2017). the study by karabo further reported that the buffer zones/spaces for flood control, sinking sediments, silt, nutrients, pollutants, toxins and sewage treatment have been turned into built-up environment which explains the growing problem of flooding and water quality in the wetland catchments (karabo, 2017). a significant number of low income earners find affordable and cheap temporal housing along nsooba lubigi drainage system and wetland. some of the residents around masanafu, sentema, namungoona and bulaga settlements depend on harvesting of papyrus materials from lubigi wetland as a way of making the ends meet. the degraded natural and cultural characteristics of the nsooba channel and lubigi wetland show lack of clear channel management policies. the location of nsooba lubigi drainage system makes it suitable for providing exceptional and important ecological services to the residents of kawempe division and kampala city at large. nsooba lubigi drainage system is consequently meant to play an important role in preserving the quality of both water supply and open waters. this signifies that areas made of urbanization, bare land, as well as farming activities are characterized by a significant population size that could be partly contributing to water quality and soil quality deterioration in the area. conclusion & recommendation the analytical concentrations of land-use types of wetland, built up areas and agriculture was observed for the parameters ec, tds, tp, bod,cod , tss, toc , where the observed average values were all below the national standards of 1000 µs/cm, 750 mg/l, 10mg/l, 50mg/l, 70mg/l, 50mg/l and 50mg/l respectively. for tn, the average value for built-up areas was higher than the national standard of 10 mg/l while the remaining land use types of wetland and agriculture were below that of the recommended standard. there was a significant decline in land coverage for wetlands and bare land from 1998-2018 attributable to rapid urban development involving infrastructural development, farming activities and rapid population growth. wetland coverage declined by approximately 5 hectares since 1998 which represents an average decline of 2 hectares per decade. bare land was also observed to have declined from 14.5% in 1998 down to 7% by 2018, signifying a rapid decline of about 50% from 1998 to 2008. the percentage changes for wetlands, agriculture, bare land and built-up areas between 1998 and 2018 were observed to be -32.63%, 16.42%, 7.43% and 23.64% respectively. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 13-28 27 the nsooba lubigi drainage system, with its natural status is potentially susceptible to land use changes attributed to anthropogenic pressures. the physical and chemical examination of water quality revealed that built up area (kalerwe) had the highest level of pollution attributed to rapid population growth and human activities including nsooba slaughter house that discharges untreated effluents to nsooba channel. the findings of this research can offer scientific orientation for land use management and water pollution regulation as well as guide in the creation of strategies for managing the water and other natural resources. however, other factors associated with water quality, such as the weather, precipitation, and density of population call for further research. from the findings of this study, a degraded land cover pattern in the nsooba lubigi catchment is evident. the study concludes that the people settling around nsooba lubigi wetland system are victims of the lubigi wetland system environmental degradation challenges and must be involved in finding solutions to these problems. this calls for the communities in the study area to assume responsibilities in guiding and controlling its development with the help of responsible government institutions like nema and research institutions. our results suggest an urgent need for formation of community based management committees and by-laws to protect the fragile wetland ecosystems in kampala city which are critical in biodiversity conservation, flood control and waste wastewater treatment. acknowledgement the authors are grateful to the uganda ministry of water and environment (mwe) for providing laboratory facilities for water analysis. denis ekakoro is acknowledged for gis technical support. references chapman d. 1992. water quality assessments a guide to use of biota, sediments and water in environmental monitoring second edition, 1996 unesco/who/unep. isbn 0 419 21590 5 (hb) 0 419 21600 6 (pb) daniel t.c. 1990. measuring the quality of the natural environment: a psychophysical approach. am. psychol. 45(5) 633 – 637. ding j., jiang y., fu l., liu q., peng q. and kang m. 2015. impacts of land use on surface water quality in a subtropical river basin: a case study of the dongjiang river basin, southeastern china. water 7(8): 4427-4445 edokpayi j.n., rogawski e.t., kahler d.m., hill c. l., reynolds c., nyathi e., smith j.a.j., odiyo j.o., samie a., bessong p. and dillingham r. 2018. challenges to sustainable safe drinking water: a case study of water quality and use across seasons in rural communities in limpopo province, south africa. water (basel). 10(2): doi: 10.3390/w10020159. fierro p., valdovinos c., vargas-chacoff l., bertrán c. and arismendi i. 2017. macro invertebrates and fishes as bio indicators of stream water pollution. in: tutu h. 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modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction preliminaries intuitionistic fuzzy set operations over intuitionistic fuzzy sets multi-objective programming problem mathematical formulation of problem intuitionistic fuzzy multi-objective linear decision-making problem intuitionistic fuzzy goal model of if-moldmp proposed solution method extended yager-membership function in the ifde develop a new intuitionistic fuzzy (if) aggregation operator the intuitionistic fuzzy goal programming method interactive penalty function method (ipfm) algorithm for penalized ifgp method numerical example results and discussion conclusion introduction mathematical model formulation the modified mathematical model model formulation qualitative analysis of the modified model well-posedness steady state basic reproduction number local stability of disease free equilibrium global stability of disease free equilibrium endemic equilibrium point local stability of endemic equilibrium bifurcation analysis sensitivity analysis numerical simulations and discussion extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion east afr. j. biophys. comput. sci. (2025), vol. 6, issue. 1, 33-45 *corresponding author: email: tibebu.alemu@ambou.edu.et, +251909117127 https://dx.doi.org/10.4314/eajbcs.v6i1.4s the effect of cuo nanoparticle variation on the green synthesized zno/cuo nanocomposites for antibacterial activities bulti abdisa kerayu1, hundessa alemu1, gemechis fikadu1, asefa keneni2, tibebu alemu1,3* 1department of chemistry, college of natural and computational sciences, ambo university, ambo, ethiopia 2department of biology, college of natural and computational sciences, ambo university, ambo, ethiopia 3school of graduate studies, ambo university, ambo, ethiopia keywords: orange peel extract; zno/cuo nanocomposites; antibacterial activity; surface characterization; green synthesis; uv-vis spectroscopy abstract plant extracts play critical role in synthesizing nanomaterials for a wide range of applications in human health and managing environmental pollutions. the present work focuses on varying cuo np’s concentration in zno/cuo nanocomposites (nc) synthesized with orange peel extracts (zno/cuo we nc) for its antibacterial activities. the concentration of cuo with respect to zno np fixed in 10:10, 10:20, 10:30, and 10:40. the as-synthesized nc is characterized using uv-vis, ftir, xrd, and sem spectroscopes. accordingly, the uv-vis result reveals that the absorption spectra range from 312-328 nm confirming the incorporation of extract to provide strong absorption peaks along with the increasing concentration of cuo in the nanocomposite while it energy band gap of zno/cuo we nc was narrowed from 3.97 to 3.78 ev. ftir analysis revealed that the stretching vibration of zn-o and cu-o are observed around 480 cm-1 and 600 cm-1, respectively in all ratios of we nc. xrd indicated that the formation of hexagonal wurtzite structure and the crystallite size recorded in 24.12 to 3.17 nm. the sem image showed the morphology of 10:20, 10:30, and 10:40 are aggregated, smooth, polished, and smaller size compared to 10:10 zno/cuo we nc. the antibacterial activities of 10:10, 10:20, 10:30, and 10:40 zno/cuo we nc were remarkable especially, 10:40 zno/cuo we nc provided strong activity against p. aeruginosa. thus, the assynthesized 10:40 zno/cuo we nc is so profound to combat bacterial infectious diseases. introduction nanotechnology is a rapidly evolving science field focused on the design, synthesis, and manipulation of materials (nanomaterials) at the nanometric scale (1–100 nm) with wide-ranging applications (singh et al., 2015). among nanomaterials, metal oxide nanoparticles (nps) have garnered significant attention because of their unique phyisicochemical properties, including high surface area, chemical stability, and antimicrobial efficacy (mihindukulasuriya and lim, 2014; benelmekki, 2015; khan et al., 2019; kumari et al., 2023). the growing east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs research article east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 33-45 34 challenge of antibiotic resistance necessitates an alternative antimicrobial strategies, and metal oxide nps have emerged as promising candidates due to its stability and broadspectrum activity (sawai, 2003; shi et al., 2014). for example, zinc oxide (zno) and copper oxide (cuo) nps exhibited antibacterial effects through multiple mechanisms, including reactive oxygen species (ros) generation, membrane disruption, and ion release leading to bacterial cell death (mantecca et al., 2015). zno, an n-type semiconductor with a wide band gap (3.37 ev), offers excellent stability and biocompatibility, making it suitable for biomedical and environmental applications (sirelkhatim et al., 2015; bekru et al., 2022). in contrast, cuo, a p-type semiconductor with a narrow band gap, demonstrates strong antibacterial and antifungal properties due to its ability to generate ros (yulizar et al., 2018; naseem and durrani, 2021). the integration of zno and cuo in to nanocomposites (ncs) enhances charge separation, reduces electronhole recombination, and improves visible-light absorption, thereby augmenting their antibacterial effectiveness (bekru et al., 2022). scholars have developed various synthesization techniques of nps, among which green methods have emerged as a promising approach that leverages plant-derived biomolecules. these synthesis methods offer several advantages over conventional or widely accepted approaches, including sustainability, reduced toxicity and controlled particle morphology (abid et al., 2022; kumar et al., 2023). example, zno nps synthesized using orange peel extract effectively inhibited e. coli and s. aureus under ambient conditions (thi et al., 2020). in similar case, zno/cuo ncs have been prepared using zingiber officinale extract demonstrated strong antibacterial effect against both gram positive and gram negative bacterial (takele et al., 2023). in addition, gao et al., (2020) reported that biogenic zno nps enhanced the shelf-life of fresh strawberries, highlighting their potential in food preservation (luque et al., 2018; gao et al., 2020). recently, alemu et al. (2023) developed zno/cuo ncs in orange peel extract and recorded outstanding inhibition of grampositive bacteria growth. although the aforementioned and other studies demonstrated exceptional antibacterial performance upon cuo nps incorporation, the optimal concentration for maximum antibacterial effect or efficacy was not clearly determined yet. therefore, a systematic investigation into the effect of cuo nps concentration in the ncs on bacterial growth inhibition remains unexamined. this research aims to address the gap observed through optimizing the cuo np content in zno/cuo ncs synthesized using orange peel extract and concomitantly assessed their antibacterial effectiveness against selected bacterial strains. the findings will contribute to the growing field of green nanotechnology by providing scientific insights into the synthesis, optimization, and antibacterial applications of zno/cuo ncs, thereby promoting sustainable and effective antimicrobial solutions. materials and methods materials zinc nitrate hexahydrate (zn (no3)2.6h2o, purity: 99%, india), zinc acetate dihydrate (zn(ch3coo)2.2h2o, purity: 98%, india), copper (ii) nitrate trihydrate (cu(no3)2.3h2o, uni-chem chemical reagents, purity: 99%, india), sodium hydroxide (naoh, ran chem east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 33-45 35 industry and trading, purity: 99.5%, germany), absolute ethanol (ch3ch2oh, purity: 99.99%, india) analytical grades were used for this study. pseudomonas aeruginosa (gram-negative) and staphylococcus aureus (gram-positive) bacteria were isolated, cultured and tested in biology laboratory, ambo university, ethiopia. preparation of orange peel extract orange peels were collected from the market of ambo town, oromia region, ethiopia. after thoroughly washing and rinsing with deionized (di) water, the fruit was peeled, air dried for 12 hours and about 4 kg taken which was ready for extraction process. the dried peel was then ground into a moderately fine powder. afterward, 1 gm of the powder was placed in different glass containers with 50 ml of di water in each container and was stirred for 3 hrs. once macerated, each mixture was placed in a water bath for 60 min at 60 ºc. finally, the mixture was filtered, and the resulting extract was stored (figure 1) in a refrigerator of 4 ºc (manokari et al., 2016). figure 1: orange fruits peel purchased from ambo market for extraction process synthesization of zno/cuo nanocomposite (nc) with orange peel extract (we) the zno/cuo nc in orange peel extract (zno/cuo we) was prepared via mixing 2 g of each zn (no3)2.6h2o and zn (ch3coo)2.2h2o dissolved separately in 42.5 ml of orange peel extracts. this mixture was then continuously stirred for 60 min once placed in a water bath at 60 ºc. subsequently, the mixture was dried at 150 ºc and then heated for 1 hr at 400 ºc. the organic substances in orange peel extract supposed to act as ligating agents as shown in alemu et al., (2023). the hydroxyl aromatic ring groups in the extract could form complex molecules with zn2+ and cu2+ ions. through, the process of nucleation and shaping followed by calcination at 400 ˚c, it was resulted in the formation of zno/cuo nc (çolak and karaköse, 2016). the concentration of zno/cuo we varied from 10:10, 10:20, 10:30 and 10:40 ppm in the ratio of zno:cuo np via changing the concentration of only cuo np to study its effect on the antibacterial activity (singh et al., 2018).(j. singh et al., 2018). reaction mechanism in the synthetization of zno/cuo we nc figure 2 display the possible reaction mechanism during the synthesis process of zno/cuo nc using orange peel extract (ligation process takes place between the functional groups of the orange peel and the respective precursors). the phytochemicals components in orange peel extracts could act as ligand agents and forms complex compounds between oh group of the organic molecules and zn2+ and cu2+ ions. the corresponding nanoparticles are formed and stabilized through a nucleation process, while the mixture of organic components decomposes upon calcination, reducing the ions and resulting in the formation of zno/cuo nanocomposites (thi et al., 2020). lastly, zn0 and cu0 gets oxidized to mixture of zno/cuo nc upon calcination (ahmed et al., 2022) while the presence of organic components are used as capping agent east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 33-45 36 to prevent the nps agglomerations (veisi et al., 2021). figure 2: proposed mechanism for the formation of functionalized zno/cuo we nc. characterization of zno/cuo we nc the surface characterizations of zno/cuo we nc were studied using x-ray diffraction (xrd) (shimadzu corporation (japan), xrd-7000 x-ray diffractometer) for crystalline structure study. fourier transform infrared (ftir) (is 50 abx, germany) was used to reveal functional group of nc. whereas, uvvis spectrophotometer (optizen top, korea) was used to investigate the chemical properties and its energy band gap while the morphology of zno/cuo we nc was characterized by scanning electron microscope (sem) (evo18, carl zeiss). antibacterial activities the antibacterial activities of the synthesized zno/cuo we were done using two human pathogenic bacteria strains i.e., staphylococcus aureus (gram-positive) and pseudomonas aeruginosa (gram-negative). the agar well diffusion method was used for the evaluation of the antibacterial activity of as-synthesized zno/cuo we nc. muller hinton (mh) agar plates were prepared, sterilized, and solidified. after solidification, 106 colony forming units (cfu) of bacterial cultures were swamped on solidified mh agar plates. five wells were cut out in the agar layer of the plate using an aluminum bore of 2 mm diameter for the east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 33-45 37 synthesized zno/cuo we nc (perez-gavilan et al., 2021) with different concentration (10:10, 10:20, 10:30, and 10:40 for zno:cuo). then, 50 l of each of the synthesized nc, positive control (cloxacillin), and negative control (dmso) was dropped into the wells using a micropipette and then incubated at 37 ◦c for 18 hrs. at the end of the incubation period, the antibacterial activities of the synthesized nc were checked by observing and measuring the zone of inhibition. results and discussion characterization of nanocomposite uv-vis spectroscopic analysis: the uv-vis spectra of the 10:10, 10:20, 10:30, and 10:40 zno/cuo we nc is shown in figure 3. the absorption peaks of the as-synthesized nc were found at the interval of 320-334 nm which fall under visible region and its sharp absorption feature indicates that each ratio of zno:cuo nc is monodispersed in nature. the uv-vis spectra signify that the strong absorption peaks (figure 3(a)) has formed in the visible region, which ascribed the presence of biomolecules from the orange peel extract (dey et al., 2021). these characteristic absorbance peaks for each zno:cuo ratio indicate the successful formation of ncs with adsorbed biomolecules. the results indicate that the synthesized zno:cuo we ncs achieved optimal reduction for tested ratio whereas 10:20 zno:cuo we nc exhibited highest absorbance at longer wavelength comparing to the remaining components. this spectral shift is attributed to the formation of smaller particle sizes comparing to 10:10, 10:30 and 10:40 zno:cuo we ncs as a result of the quantum confinement effect (matinise et al., 2017). in addition, the 10:20 zno:cuo we nc possesses the lowest energy band gap (table 1) suggesting enhanced electron mobility. figure 3: uv-vis spectra (a), tauc plot for the energy bandgap determination for zno/cuo (10:10, 10:20, 10:30 and 10:40). east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 33-45 38 the band gap energy of the synthesized nps was determined using equation (eq. 1) below. ௚ܧ = ℎܿ ൗߣ (1) where, h = planck’s constant (6.63 x 10-34 m2 kg s-1), c = speed of light (3.00 x 108 ms-1), λ = absorption wavelength in uv region (330 nm). the energy band gap values for the synthesized zno/cuo we ncs, as presented in table 1, were calculated to be 3.97 ev, 3.78 ev, 3.85 ev, and 3.83 ev for the 10:10, 10:20, 10:30, and 10:40 ratios, respectively. these results indicate that as the zno:cuo ratio changes from 10:10 to 10:20, the band gap energy decreases (eq. 1), suggesting that the 10:20 zno/cuo we nc exhibits the most effective visible light absorption. this finding aligns with the results obtained from the tauc plot. furthermore, the experimental results are consistent with theoretical values, which typically range from 3.02 to 1.47 ev. however, the observed band gap values are slightly higher than those reported by qamar et al. (2017). the uv-vis absorption spectrum of the synthesized nps shows absorption at lower wavelengths (312– 328 nm) for all ncs. therefore, uv-vis spectroscopy characterization further confirms the successful formation of zno/cuo we ncs in the expected absorption range. table 1: the energy band gap calculated from uv-vis data for zno/cuo we nc. ration of zno/cuo we nc wavelength (ૃܠ܉ܕ) in nm the energy band gap (ebg) in ev 10:10 312 3.97 10:20 328 3.78 10:30 322 3.85 10:40 324 3.83 ft-ir spectroscopic analysis: ft-ir spectra of the prepared zno/cuo we nc were recorded to determine its functional groups in the range of 4000–400 cm−1 (figure 4). according to the results, the spectra of all ratios in zno/cuo we nc demonstrated the absorption band exhibited at 3200-3500 cm-1 represents the stretching vibrations of –oh group of adsorbed h2o molecule on the surface of ncs (nuisin et al., 2022). on the other hand, the stretching vibrations observed at 1105, 1391, 1590 and 1606 cm-1 show c-o stretching, c-h bending, c=o and c=c bonds (berra et al., 2018), respectively in all combination. in addition, the intense absorption peaks observed at 609, 715, and 973 cm⁻¹ correspond to the stretching vibrations of zn–o, cu–o, and zn– o–cu bonds within the nanocomposites (li et al., 2022). the intensity of these peaks increased with the rise in cuo concentration, while the nature of the functional groups remained unchanged, confirming that the composition of the nanocomposites remained consistent across different cuo concentrations. east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 33-45 39 figure 4: ftir spectra of synthesized zno/cuo we nc. x-ray diffraction (xrd) analysis: the xrd patterns of zno/cuo we ncs are shown in figure 5, covering the 2θ range of 10–80°. the diffraction peaks for zno/cuo we ncs with different concentrations were observed at 2θ = 35.90°, 36.76°, 42.40°, and 42.51°, corresponding to the lattice planes (002), (101), (012), and (012), respectively. these peaks confirm the hexagonal crystalline phase of the zno/cuo we ncs, agreed with the jcpds card no. 36-1451. additionally, a slight shift in the 2θ positions of certain peaks was observed. this shift may be attributed to variations in cuo concentration during the preparation of the samples using orange peel extract, which could influence the crystallographic structure of the ncs. the average crystalline size of zno/cuowe ncs for each ratio is calculated using debye-scherrer's equation. figure 5: xrd patterns of the as-synthesized zno/cuo we nc. accordingly, the average crystalline size (dp) of 10:10, 10:20, 10:30 and 10:40 zno/cuo we nc were 24.12, 16.33, 6.64 and 3.17 nm (table 2). the result confirmed that the size of the ncs has decreased as the increasing concentration of cuo within the composites. in the current study, the presence of different functional groups including c–o, c=o, and o–h in the plant extract contribute to stabilizing particles while an increase amount of cuo increase the crystal growth of zno/cuo we nc. east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 33-45 40 table 2: crystalline size determination for zno/cuo-we nanocomposites. nanocomposite 2θ θ cosθ fwmh in rad size/nm aver/nm cuo/zno (10:10) 32.3 16.15 0.96053 0.3548 0.00603 23.95119 24.12 34.1 17.05 0.95604 0.3705 0.00629 23.04399 36.71 18.355 0.94909 0.3392 0.00576 25.35469 cuo/zno (10:20) 27.46 13.73 0.97142 0.54702 0.00929 15.36071 16.33 36.71 18.355 0.94909 0.52469 0.00892 16.39122 42.44 21.22 0.93219 0.50779 0.00863 17.24380 cuo/zno (10:30) 18.58 9.29 0.98688 1.4827 0.02521 6.713731 6.64 24.69 12.345 0.97685 1.2446 0.02116 6.713731 35.20 17.6 0.95319 1.3191 0.02242 6.491789 cuo/zno (10:40) 22.97 11.485 0.9799 2.6707 0.04541 3.118995 3.17 33.46 16.73 0.95767 2.6707 0.04541 3.191395 35.95 17.975 0.95119 2.6707 0.04541 3.213137 analysis of surface morphology: the morphology of 10:10, 10:20, 10:30, and 10:40 for zno/cuo we nc was studied using sem (figure 6). the sem image of 10:10 zno/cuo we nc indicates that the crystal formed has cluster and flake-like structure while the particles are agglomerated in nature. figure 6: sem images of zno/cuo we nc (a) 10:10, (b) 10:20, (c) 10:30, and (d) 10:40 in zno:cuo ratio. (a (d(c) (b east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 33-45 41 the images of the 10:20 and 10:30 zno/cuo we ncs exhibit aggregated, smooth, and polished surfaces with smaller particle sizes compared to 10:10 zno/cuo we nc. notably, the 10:40 zno/cuo we nc displays a finer distribution of smaller particles with a porouslike structure. these findings confirm that the grain size and overall morphology of the synthesized ncs are strongly influenced by the cuo np concentration under identical reaction conditions. furthermore, the crystal sizes of 10:10, 10:20, 10:30, and 10:40 zno/cuo we ncs increased, as determined using the scherrer equation. the images clearly reveal microstructural heterogeneities and distinct morphological differences among the synthesized ncs, highlighting the effect of cuo content on their structural properties. study of antibacterial activity for each synthesized nanomaterial, the zone of inhibition (zoi) values was recorded as shown in table 3. the antibacterial effect of nanomaterials against both bacteria compared with control samples, the diameter of zoi varied at the different concentration levels of ncs. the three trials of antibacterial activities of 10:10, 10:20, 10:30, 10:40 zno/cuo we nc were measured and showed a good response against s. aureus with an average maximum zoi of 17.33, 21.66, 25.33 and 28.66 mm while its activity against p. aeruginosa was shown relatively higher zoi of 21.00, 25.66, 28.33 and 30.66 mm after 18 hrs incubation times. this indicates that 10:10, 10:20, 10:30, and 10:40 zno/cuo we nc in particular 10:40 zno/cuo we nc are more effective for p. aeruginosa than s. aureus bacterial strain. table 3: antibacterial activity of nc applied to two human pathogenic bacteria. nanocomposites test organism zone of inhibition (mm) trial-1 trial-2 trial-3 average cloxacillin 10:10 zno/cuo we nc s. aureus 14 13 25 17.33 35 p. aeroginosa 22 27 14 21.00 35 10:20 zno/cuo we nc s. aurous 19 22 24 21.66 35 p. aeroginosa 27 20 30 25.66 35 10:30 zno/cuo we nc s. aurous 25 26 25 25.33 35 p. aeroginosa 30 30 25 28.33 35 10:40 zno/cuo we nc s. aurous 29 30 27 28.66 35 p. aeroginosa 30 35 27 30.66 35 this suggests that gram-negative bacteria exhibited higher susceptibility to the synthesized 10:40 zno/cuo we nc, as their loosely structured cell membranes provide less protection against external attacks. figure 7 and 8 confirm the formation of larger inhibition zones for bacterial strains, represented as 1 (10:10), 2 (10:20), 3 (10:30), and 4 (10:40) zno/cuo we nc, against gram-positive and gram-negative bacteria, respectively. the highest concentration (sample 4) demonstrated the most effective zone of inhibition (zoi) compared to the others. therefore, the antibacterial effectiveness of the nanomaterials increases with the cuo np concentration in the east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 33-45 42 zno/cuo we nc synthesized using orange peel extracts (wang et al., 2017). figure 7: the antibacterial activity of zno/cuo we nc against s. aureus bacteria. figure 8: the antibacterial activity of zno/cuo we nc against p. aeroginosa bacteria the results of this study indicated that the antibacterial activities of 10:10, 10:20, 10:30, and 10:40 zno/cuo we nc is cuo np concentration dependent. the negative control (dmso) did not show any zoi whereas the positive control (cloxacillin) showed the highest zoi. based on the results of the current study, it was evident that the zoi of samples (figure 7 and 8) showed that the synthesized compounds significantly inhibited the selected bacterial probably by generating ros species that can easily penetrate the bacterial wall particularly when the ratio of zno to cuo we changed from 10:10 to 10:40. the ros generated by nc provides better contact environment with bacteria (khan et al., 2016; kumar et al., 2017). therefore, this study provides valuable insights into overcoming bacterial resistance to standard antibiotic drugs and offers a potential solution to serious healthrelated issues. the synthesized nanocomposite (nc) could serve as a viable alternative to antibiotic-resistant drugs due to its costeffectiveness, non-toxic nature, and sustainable production from renewable and environmentally east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 33-45 43 friendly materials (chinemerem nwobodo et al., 2022). conclusion in this work, we have studied the effect of cuo np concentration variation of zno/cuo nc prepared with orange peel extract for the study of antibacterial activities. the as-synthesized materials were characterized by sem, xrd, ftir, and uv-vis for the investigation of its morphology, crystal structure, functional group, and energy band gap. the xrd study confirms the formation of hexagonal wurtzite structure and the crystallite size of 24.12 3.17 nm, the vibrational stretching band was found around 480-600 cm-1 reveal that the we nc possesses the metal-oxygen bonds, and sem image signify that each ratio of zno/cuo we nc affects the grain size and anti-bacterial activity of zno/cuo we nc. the characteristic absorption peak observed at 312-328 nm also supports the formation of 10:10, 10:20, 10:30, and 10:40 of zno/cuo we nc with a very narrow energy gap with 3.97-3.78 ev. among all we nc with various zno:cuo nc ratio, 10:40 zno/cuo we nc exhibited better antibacterial activity against both human pathogens particularly to p. aeroginosa bacteria. declaration of interest the authors declare no conflict of interest. acknowledgements the author would like to forward heartfelt gratitude to ambo university for providing the essential facilities and support that contributed to the successful completion of this research. references abid n., khan a. m., shujait s., chaudhary k., ikram m., imran m., maqbool m. 2022. synthesis of nanomaterials using various top-down and bottomup approaches, influencing factors, advantages, and disadvantages: a review. adv. colloid interface sci. 300: 102597. ahmed a. a., rizvi z. r., shahzad h. and farrukh m. a. 2022. neodymium oxide nanoparticles synthesis using phytochemicals of leaf extracts of different plants as reducing and capping agents: growth mechanism, optical, structural and catalytic properties. j. chin. chem. soc. 69(3): 462-475. alemu t., asefa g., shumbura m., kenani a. and tullu a. m. 2023. biosynthesization of zno/cuo nanocomposites in orange peel crude extract for antibacterial activities. j. sci. sustain. dev. 11(2): 94-110. bekru a. g., tufa l. t., zelekew o. a., goddati m., lee j. and sabir f. k. 2022. green synthesis of a cuo– zno nanocomposite for efficient photodegradation of methylene blue and reduction of 4-nitrophenol. acs omega 7(35): 30908-30919. benelmekki m. 2015. an introduction to nanoparticles and nanotechnology. in: benelmekki m. 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(2023), vol. 4, issue. 1, 42-51 *corresponding author: email: haftish1@gmail.com, 251 926046602 https://dx.doi.org/10.4314/eajbcs.v4i1.4s synthesis, characterization and antibacterial activity of benzimidazole derivatives and their cu (ii), ni (ii) and co (ii) complexes haftom welderufael*, dagne addisu kure, endalkachew asefa moges, lelisa file, salah hamza sherif department of chemistry, hawassa university, hawassa, ethiopia keywords: antibacterial; benzimidazole; metal complex; schiff base abstract benzimidazole is one of the privileged nitrogen-containing heterocyclic compounds, which is found in many bioactive compounds, benzimidazole and its derivatives have evolved as an important heterocyclic system due to their potency in a wide range of biologically active compounds like anthelmintic, antibacterial, antifungals, antiinflammatory, antiviral, and so on. derivatives of 1-arylsulfonylbenzimidazole and their respective cu (ii), ni (ii) and co (ii) complexes were successfully synthesized. the structures of all the synthesized ligands were confirmed by using ir, uv-visible, 1h nmr, and 13c nmr spectroscopy. the cu (ii), ni (ii) and co (ii) complexes were confirmed by using ir and vu-visible spectra. the ir spectra of ligands and its metal complexes imply that the benzimidazol derivative ligands behave as basic bidentate ligands coordination through the azomethine nitrogen and oxygen atom. in-vitro antibacterial activity of all the synthesized ligands and their metal complexes were evaluated by using disc diffusion method against k. pneumoniae, e. coli, and s. aureus bacterial species .the tested compounds and metal complexes exhibited from good to excellent activity (zone of inhibition (zi) ranged 10 mm to 23 mm). compound bil1 exhibited better activity than the standard drug against e. coli (zi of 15 mm) and k. pneumoniae (zi of 5 mm) compared with gentamycin ((zi of 15mm). complex coc exhibited better activity against s. aureus (zi of 23 mm) compared with gentamicine (zi value of 21 mm). this compound is a good starting point to develop new drug for treating pathogenic diseases. therefore, synthesis of more analogue were recommended for further discovery of a new drug candidate. introduction microbial resistance is one of the critical public health issues and the greatest challenges of the twenty-first century (marinescu, 2021) especially as increasing numbers of strains are becoming resistant to multiple antimicrobial agents, with some bacteria now being resistant to all available antibiotics, there is an pressing need to develop new drugs with novel mechanisms of action (fatmah et al., 2015). nitrogenheterocycles play a vital role in medicinal chemistry and they have been intensively used as scaffolds for drug development, among nitrogen containing heterocyclic compounds, benzimidazole is continuously drawing the interest of many researchers for the east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article https://dx.doi.org/10.4314/eajbcs.v4i1.4s east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 42-51 43 development of newer drug moiety (majumder et al., 2013). benzimidazole derivatives are known to possess varied biological activities, substituted benzimidazole derivatives have been reported to possess antimicrobial (ansari et al., 2009; özkay et al., 2010; shaharyar et al., 2017), anti-inflammatory (mariappan et al., 2015; achar et al., 2017), and antiviral (zou et al., 1996; s. hirashima et al., 2006; bhagdev, k. and sarkar, 2021), anticancer (błaszczak-s´ et al., 2014; sharma et al., 2017; ting-ting et al, 2018) activities. the structural similarity of the benzimidazole moiety to naturally occurring nucleotides makes it a valuable drug scaffold in medicinal chemistry. the strong link between the benzimidazole core and a wide range of biological activities is welldocumented and established in the literature. benzimidazole derivatives have also been used as good ligands for transition metal ions due to the large conjugated pi-system and the azomethine nitrogen which can positively affect the structures of the complexes (galal et al., 2010). due to their potent biological activity, metal complexes with aromatic schiff base ligands, particularly those based on imidazoles, have gained considerable interest in recent years (kumaravel et al., 2017). the biological activities of several metal complexes with benzimidazole ligands have been created and investigated (horacio et al., 2008; kopel et al., 2015; ashraf et al., 2016; kumaravel and raman 2017). in this paper, the synthesis and antibacterial activity investigations of benzimidazole derivatives and their metal complex against k. pneumonia, e. coli, and s. aureus bacterial strains were presented. these bacteria were selected on the basis that e. coli known to cause urinary tract infections, k. pneumoniae know to be the causative agent of pneumonia and s. aureus is multi drug resistant (abioye et al., 2013). therefore, the objective of this study was to compare the activity of the ligands with their metal complexes. materials and methods all reagents and solvents were of analytical grade and used as received. reaction mixtures were monitored via thin-layer chromatography (tlc) on silica gel plates. column chromatography employing silica gel (100– 200 mesh) was primarily used for purification of the intended products. melting points were determined using open capillary tubes and are reported uncorrected. infrared (ir) spectra were collected on an ft-ir bruker alpha spectrometer. nuclear magnetic resonance (nmr) spectra were acquired using a bruker advance nmr spectrometer operating at 400 mhz, with tetramethylsilane (tms) as the internal standard. chemistry the benzimidazole derivatives was prepared as outlined in scheme 1, the intermediate, 2substituted benzimidazole was prepared by refluxing o-phenylendiamine with appropriately substituted benzaldehyde in dimethyl formamide (dmf) in the occurrence of nahso4 as a catalyst, the benzene sulphonyl substituted compounds were prepared by stirring 2substituted benzimidazole derivatives with benzene sulphonyl chloride at room temperature in acetone in the presence of sodium carbonate. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 42-51 44 in1, r1 = och3, in2, r1= h; bil1, r2 = och3, bil2, r2 = h scheme 1: reagent and condition: a) nahso3, dmf, reflux 90-100oc; b) k2co3 acetone, rt synthesis synthesis of 2-(1h-benzo[d]imidazol-2-yl)-6methoxyphenol(in1) a mixture of o-phenylendiamine (1.09g, 10mmol) and (1.248g, 10mmol) sodium hydrogen sulphite were dissolved in 15 ml dimethyl formamide (dmf) stirred at room temperature for 30min, to this solution (1.52g, 10mmol) 2-o-vanillin were added, the mixture was refluxed for about 6hr at 90oc-100oc, the development of the reaction was regulated by tlc. at the end of the reaction, the reaction mixture was cooled and extracted with ethyl acetate. the organic layer was separated, dried over anhydrous na₂so₄, and concentrated under reduced pressure. the resulting material was purified by column chromatography using a 9:1 mixture of hexane and ethyl acetate. synthesis of 2-(1h-benzo[d]imidazol-2-yl) phenol (in2) a mixture of o-phenylendiamine (0.54g, 5mmol) and (0.624g, 5mmol) of sodium hydrogen sulphite were dissolved in 15 ml dimethyl formamide (dmf) stirred at room temperature for 30min, to this mixture (0.605g, 5mmol) salisaldehyde were added and the mixture was refluxed for about 6hrs. at 90oc-100oc,the progress of the reaction was regulated by tlc. at the end of the reaction, the reaction mixture was cooled and extracted with ethyl acetate. the organic phase was harvested and dried over anhydrous na2so4; the solvent used was removed under reduced pressure recrystallized from methanol. synthesis of n-benzenesulfonyl-2-(1hbenzo[d]imidazol-2-yl)-6-methoxyphenol (bil1) 2-(1h-benzo[d]imidazol-2-yl)-6-methoxy phenol (in1) (0.38g, 1.77mmol) were dissolved in 10 ml acetone and (0.614g, 4.429mmol) k2co3 were added and stirred at room temperature for 30min, then 0.3 ml of benzene sulfonyl chloride was added drop wise to the mixture and refluxed for 6 hours, the reaction's progress was followed by thinlayer chromatography (tlc). once complete, the reaction mixture was partitioned between water and ethyl acetate. the organic phase was collected, dried over anhydrous sodium sulfate (na₂so₄), and concentrated in vacuo. the resulting product was then subjected to column chromatography, using a 9:1 mixture of hexane and ethyl acetate as the mobile phase. synthesis of n-benzenesulfonyl-2-(1hbenzo[d]imidazol-2-yl) phenol (bil2) 2-(1h-benzo[d]imidazol-2-yl)phenol(in2) (1.15g, 5.4 mmol) was dissolved in 10 ml of acetone,k2co3(1.8g, 13.5mmol) were added east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 42-51 45 and stirred at room temperature for 30min, 0.8 ml of benzene sulfonyl chloride were added to the mixture drop wise and refluxed for 6 hours, the progress of the reaction was monitored by tlc. at the end of the reaction, the reaction mixture was cooled and extracted with ethyl acetate. the organic phase was collected and dried on anhydrous na2so4 and crystallized under abridged pressure. the product was then further purified by column chromatography. synthesis and characterization of metal complexes of bil1 a methanolic solution of ligand bil1 (0.38 g, 0.5 mmol, in 10 ml) was combined with a separate methanolic solution (5 ml) of either cu(ch₃coo)₂·h₂o, ni(ch₃coo)₂·4h₂o, or cucl₂·6h₂o (1 mmol each). the combined solutions were refluxed for 8 hours, with the reaction being monitored by thin layer chromatography (tlc). after allowing the mixture to cool in an ice bath, the precipitate was collected by filtration and washed with dichloromethane. the solid was dried under vacuum overnight, and then recrystallized from methanol. antibacterial activities culture media and disk preparation nutrient agar, muller hinton agar and nutrient broth were prepared according to the manufacturer instruction in which the prepared media was autoclaved at 121oc for 15 minutes. then the prepared culture media was checked for the sterility for 24 hours at 37 oc. for quality control, strains of staphylococcus aureus (s. aureus), escherichia coli (e. coli) and klebsiella pneumonia (k. pneumonia), which were obtained from the college of medicine and health science of hawassa university, known american type culture collection committee (atcc) were used to perform the antibacterial activities of the agents. whatman filter paper 41 is used to prepare a disk of 5mm diameter using manual paper punching. preparation of chemical slution and media for the antibacterial activity by using analytical balance, a 0.005g of each chemical powder was added to 15µl dimethyl sulphoxide (dmso) and mixed to form a homogenous solution. a 5µl of the solution was added to the sterile disk prepared before using sterile micropipette. the aforementioned bacterial strains (meant for quality control) were inoculated on sterile nutrient agar plates using sterile loop. the streaked plates were incubated for 24 hours at 37oc. a 3 to 5 colonies were picked with sterile loop and suspended in 5 ml nutrient broth to form standards. the culture suspension was then inoculated on sterile muller hinton agar plate using sterile cotton swab in three directions to get uniform inoculum. the antibiograms profiles of the test organisms to the control antibiotic were checked. then an autoclaved disks with a control gentamicin and solution impregnated disks were carefully positioned on the plate and incubated for 24 hours at 37oc. the unique id number of each disk was mentioned with permanent marker on the back of the petri dishes. after incubation the diameter of the zone of inhibition was measured using ruler. the result was given in (table 1) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 42-51 46 result and discussion characterization characterization of 2-(1h-benzo[d]imidazol2-yl)-6-methoxyphenol (in1) light red solid; yield:76.1%;mp:195-197 oc; ir(kbr, cm-1): 3394(-nh), 3240(-oh), 3047(c-h, aromatic), 2854(c-h, methyl), 1593(c=n); 1h-nmr (dmso-d6,400mhz): h 13.12(s, 1h,-oh), 7.91-789(m, 2h, ar-h), 7.73-763(m, 2h, ar-h), 7.42-7.37(m, 2h, arh), 7.26-7.25(m, 1h, ar-h), 5.00(s,1h,-nh), 3.7(s,3h,och3); 13c-nmr (dmso-d6, 100mhz): c 149.2, 147.1, 142.6, 137.0, 123.5, 122.8, 121.1, 120.1, 114.3, 111.0, 42.7 electronic spectra of compound in1 the uv-vis spectrum of the in1 compound was recorded in dmso. the electronic absorption spectrum of the ligand showed bands at 304 nm, attributed to a π-π* transition of the –c=c– bond; 382 nm, corresponding to an n-π* transition; and 497 nm, assigned to an n-π* transition of the azomethine chromophore (–c=n–). characterization of n-benzenesulfonyl-2(1h-benzo[d]imidazol-2-yl)-6methoxypheno1 (bil1) light red solid; yield:68.0%, mp:230-232oc; ir(kbr, cm-1): 3210 (-oh), 2923(c-h, aromatic), 2854(c-h), 1458(c=n), 1377(o=s=o); 1hnmr(dmso-d6,400mhz): h 13.2 (s,1h,oh), 7.9(d, j= 8.4hz,2h), 7.7(m, 2h), 7.6(d, j=7.4hz,2h), 7.5(m,1h), 7.4(d, j=6.5hz,1h), 7.3(m,2h), 7.1(d, j=7.65hz,1h), 6.9(m,1h,), 3.7(s,3h, och3); 13c-nmr (dmso-d6, 100mhz) c 153.1, 147.6, 136.0, 133.8, 129.8, 128.3, 126.9, 126.4, 123.0, 122.7, 122.5, 115.6, 115.0, 56.4 electronic spectra of compound bil1 the uv/visible spectral for bil1 compound recorded in dmso, the electronic absorption spectrum of the ligands showed band at 302nm attributed to –c=c-, * transitin, the band around 382nm and 495nm is because of n * transition of the(-c=n-) azomethine chromophore. characterization of n-benzenesulfonyl-2(1h-benzo[d]imidazol-2-yl) phenol (bil2) yellow solid; yield:71.2 %, mp:196-198 oc, ir(kbr, cm-1): 3232 (o-h), 2954(c-h, aromatic), 1458(c=n),1176 (c-o) strong band at1377 (o=s=o); 1h-nmr(400mhz, dmso-d6) h:13.15(s, 1h, -oh), 7.74-7.61(m, 5h, ar-h), 7.29-7.20(m, 4h, ar-h), 7.08-7.06 (m, 2h, ar-h), 6.97-6.91(m, 2h, ar-h); 13cnmr (100 mhz,dmso-d6) c:115.3, 118.1, 119.5, 121.3, 121.52, 121.94, 122.64, 123.0, 123.33, 128.9, 131.1, 137.9, 138.9, 141.5, 155.3 characterization of cu(ii) complexes of bil1(cuc) the product was obtained as a light brown solid with a 74.5% yield and a melting point of 214-216 °c. the ir spectrum (kbr, cm⁻¹) showed characteristic peaks at 3394 (o-h stretching of water), 2923-2858 (c-h), 1604 (c=n), and 1377 (s=o). the c-o stretch, observed at a higher frequency in the cu (ii) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 42-51 47 complexes compared to the free ligands, suggests logical coordination through the deprotonated phenolic-o. this is supported by the disappearance of the weak phenolic oh band in the complex spectra. far-infrared bands corresponding to m-o bonds, including a band at 1188 cm⁻¹ assigned to the (cu-o) bond in the complexes, further corroborate the proposed coordination mode of the schiff base ligands. the uv/visible spectra recorded in dmso, the electronic absorption spectrum of the ligands showed band at 301nmattributed to * transition of –c=c-, the band around 382nm and 502nmis due to n * transition of the (c=n-) azmethine chrmphre. s n n o o o och3 n n s o och3 o o cu oaccao h2o proposed structure of cu(ii) complex of bil1(cuc) characterization of ni(ii) complexes of bil1(nic) pale green solid, yield 76.9%, mp: 220-222oc; ir (kbr, cm−1):3240 (o-h stretching of water), 2923-2858(c-h, stretching), 1604(c=n), 1461 (c-o), 1377 (s=o). the co stretch of the free ligands was observed at a higher frequency in the spectra of the ni(ii) complexes, suggesting coordination of the schiff base ligands through the deprotonated phenolic–o, this was substantiated by the disappearance of the weak phenolic oh band in the spectra of the complexes. the mode of coordination of the schiff base ligands was further corroborated by the appearance of bands in the far-infrared spectra of the complexes due to the m-o bonds. the new bands in the low frequency region 510 and 440 are due to the formation of (m–o) and (m–n) vibrations respectively. electronic spectra of compound nic the uv/visible spectral for compound nic are recorded in dmso the data are presented in the electronic absorption spectrum revealed band at 302nm attributed to *transition of (–c=c) ,the band around 382nm and 499nm is due to *and n * transition of the (-c=n-) azomethine chromophore. s n n o o o och3 n n s o och3 o o oaccao 4h2oni proposed structure of ni(ii) complexof bil1(nic) characterization of co (ii) complexes of bil1 (coc) yellow solid, yield 88.8%, mp:210-212oc, the ir stretching (kbr, v in cm-1) spectral information for compound coc, showed distinguishing medium band at 3394cmconfirmed the presence of o-h stretching of water. strong band at 2923-2858cm-1 east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 42-51 48 guaranteed the presence of c-h stretching of aromatic. a medium band at 1604cm-1 confirmed the availability of c=n stretching of azomethine. a medium narrow band at 1461cm-1confirmed the presence of c-o stretching of aromatic. a medium narrow band at 1677cm-1 confirmed the presence of c=c stretching aromatic and the strong band at 1377cm-1 confirmed the presence of two s=o stretching of benzene sulfonyl. a higher c-o stretching frequency was observed in the infrared spectra of the co(ii) complexes compared to the free ligands, which indicates coordination of the schiff base ligands via the deprotonated phenolic oxygen. the conclusion made based on these findings was supported by the absence of the weak phenolic o-h band in the complex spectra. moreover, the farinfrared spectra of the complexes showed bands that can be assigned to m-o vibrations, including one at 1130 cm⁻¹ corresponding to the co-o bond. electronic spectra of compound coc the uv/visible spectra for compound coc were noted in dmso, the electronic absorption spectrum of the ligands showed band at 267nm associated with –c=c, * transition, the band around 302nm and 319nm is because of *and n * transition of the-c=n-azomethine chromophore. no spectral bands were found below 300nm which supports octahedral geometry. s n n o o o och3 n n s o och3 o o cl 6h2ococl proposed structure of co (ii) complex of bil1(coc) characterization of copper (ii) complexes of bil2 (cuc2) the light brown solid, cuc2, was obtained with an 86.7% yield and a melting point of 160-162 °c. the ir spectrum (kbr, cm⁻¹) exhibited a medium band at 3363 cm⁻¹ indicative of o-h stretching from water, strong bands at 2923-2858 cm⁻¹ due to aromatic c-h stretching, a medium band at 1612 cm⁻¹ consistent with c=n stretching in the azomethine, a medium narrow band at 1461 cm⁻¹ corresponding to aromatic c-o stretching, a medium narrow band at 1917 cm⁻¹ assigned to aromatic c=c stretching, and a strong band at 1377 cm⁻¹ suggesting two s=o stretching in the benzene sulfonyl group. a shift to higher frequency in the c-o stretching band was observed for the co(ii) complexes compared to the free ligands, indicating coordination of the schiff base ligands through deprotonated phenolic oxygen. this observation was substantiated by the absence of the characteristic phenolic oh band in the complex spectra. additionally, the far-infrared spectra of the complexes exhibited east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 42-51 49 bands that can be attributed to m-o vibrations, including one at 1170 cm⁻¹ corresponding to the co-o bond. electronic spectra of compoundcuc2 the uv/visible spectral for compound cuc2 are recorded in dmso. the data are offered in the electronic absorption spectrum of the ligands showed band at 274nm (36496cm-1) attributed to –c=c-, *transition the band around 300nm and 332nm due to *and n *transition of the (-c=n-) azomethine chromophore. no spectral bands were found below 10000cm-1 which supports octahedral geometry. s n n o o o n n s o o o oaccao h2o cu proposed structure of cu(ii) complex of bil2 (cuc2). table-1: in-vitro antibacterial activity values of the synthesized benzimidazol derivatives and their cu(ii), ni(ii) and co(ii) complexes the synthesized benzimidazol derivative and cu(ii), ni(ii) and co(ii) complexes were tested for in-vitro antibacterial activity against e. coli, s. aureus and k. pneumonia. gentamicin was used as standard antibacterial drug. the zone of inhibition values clearly showed that all the compounds exhibited a varied range 5-23mm (table 1) against all the tested bacterial strains. compounds in, bil2 and cuc2 had less activity against e. coli and s. aureus. compounds nic and cuc showed moderate antibacterial activity against e. coli and s. aureus. compound bil1 exhibited better activity against e. coli (15mm zone of entry compounds zone of inhibition (in mm) e. coli s. aureus k. pneumonia 1 in1 5 10 5 2 bil 1 15 18 8 3 bil2 5 7 5 4 cuc [cu(bil1)2(oac)2].h2o 11 18 8 5 nic [ni(bil1)2(oac)2].4h2o 10 20 6 6 coc [co(bil1)2(cl)2].6h2o 12 23 11 7 cuc2 [cu(bil2)2(oac)2].h2o 5 5 5 standard gentamycin 14 21 5 east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 42-51 50 inhibition) compared to standard (14mm zone of inhibition) but moderate activity against s. aureus; compound coc exhibited better activity against s. aureus (23mm zone of inhibition) compared to standard (21mm zone of inhibition) but moderate activity against e. coli. conclusion all the synthesized compounds in this study showed better activity against k. pneumonia compared to standard. comparing the two benzimidazole derivatives bil1 and bil2; bil1 showed better activity against all the tested bacterial strain, structurally the two compounds are differ by the presence of methoxy substituent at 3 position of phenyl ring, it can be concluded that the dramatic increase in the activity is due to the presence of this substituent. this compound is a good starting point to develop new drug for treating pathogenic diseases. therefore, synthesis of more analogue were recommended for further discovery of a new drug candidate. acknowledgement the authors thank addis ababa university for running the nmr, ir, and uv-vis spectra and hawassa university for providing research funding. references ashraf a., siddiqui w. a., akbar j., mustafa g., krautscheid h., ullah n., mirza b., sher f., hanif m. and hartinger c.g. 2016. metal complexes of benzimidazole derived sulfonamide: synthesis, molecular structures and antimicrobial activity. inorganica chimica acta 443: 179–185. arpi m., ragini g. and anshu j. 2013. microwaveassisted, synthesis of nitrogen-containing heterocycles. green chemistry letters and reviews 6:2, 151-182, bhagdev k. and sarkar s. 2021. benzothiazole moiety and its derivatives as antiviral agents. med. sci. forum. 7 (1): 1-9 fatmah a.s. alasmary, snelling a.m., zain m.e., alafeefy a.m., awaad a.s. and karodia n. 2015. synthesis and evaluation of selected benzimidazole derivatives as potential antimicrobial agents. molecules 20(8): 15206– 15223, kumaravel g. and raman n. 2017. a treatise on benzimidazole based schiff base metal(ii) complexes accentuating their biological efficacy: spectroscopic evaluation of dna interactions, dna cleavage and antimicrobial screening ganesan kumaravel. mater. sci. eng. 70: 184– 194 mariappan g., hazarika r., alam f., karki r., patangia u. and nath s. 2015. synthesis and biological evaluation of 2-substituted benzimidazole derivatives. arab. j. chem. 8: 715–719 błaszczak-swiatkiewicz k., olszewska p. and mikiciuk-olasik e. 2014. biological approach of anticancer activity of new benzimidazole derivatives. pharmacol rep. 66: 100–106 kavitha a., kallappa h. and harisha s. 2010. in-vivo analgesic and anti-inflammatory activities of newly synthesized benzimidazole derivatives, eur. j. med. chem. 45: 2048–2054 ansari k.f. and lal c.. 2009. synthesis, physicochemical properties and antimicrobial activity of some new benzimidazole derivatives. eur. j. med. chem. 44: 4028–4033 horacio l.s., londonõ-lemos m. e., raúl g.-v., israel p.m. , pilar g.m., isabel g.m. and norah n.b. 2008. synthesis, structure and biological activities of cobalt (ii) and zinc (ii) coordination compounds with 2-benzimidazole derivatives. j. inorg. biochem. 102: 1267–1276 ting-ting m., xu-bing t., dong-dong l., chen h., xiaoyan j., geng y., shi-fa w. and gu w. 2018. synthesis and biological evaluation of 2-arylbenzimidazole derivatives of dehydroabietic acid as novel tubulin polymerization inhibitors. rsc adv. 8: 17511–17526 marinescu, m. 2021. synthesis of antimicrobial benzimidazole–pyrazole compounds and their biological activities. antibiotics. 10: 1002, 1-29 sharma p., reddy t.s., kumar n.p., senwar k.r., bhargava s.k. and shankaraiah n. 2017. conventional and microwave-assisted synthesis of new 1hbenzimidazole-thiazolidinedione derivatives: a potential anticancer scaffold. eur. j. med. chem. 138: 234-245 kopel p., wawrzak d., langer v., cihalova k., chudobova d., vesely r., adam v. and kizek r. 2015. biological activity and molecular structures of bis(benzimidazole) and trithiocyanurate complexes. molecules. 20: 10360-10376 east afr. j. biophys. comput. sci. (2023), vol. 4, no. 1, 42-51 51 zou r., ayres k.r., drach j.c. and townsend l.b. 1996. synthesis and antiviral evaluation of certain disubstituted benzimidazole ribonucleosides. j. med. chem. 39: 3477–3482 galal s.a., hegab k.h., hashem a.m. and youssef n.s. 2010. synthesis and antitumor activity of novel benzimidazole-5-carboxylic acid derivatives and their transition metal complexes as topoisomerease ii inhibitors. eur. j. med. chem. 45: 5685-5691 hirashima s., suzuki t., ishida t., noji s., yata s., ando i., komatsu m., ikeda s. and hashimoto h. 2006. benzimidazole derivatives bearing substituted biphenyls as hepatitis c virus ns5b rna-dependent rna polymerase inhibitors:  structure−activity relationship studies and identification of a potent and highly selective inhibitor jtk-109. j. med. chem. 49: 4721–4736 shaharyar m., mazumder a. and abdullah m. 2017. synthesis, characterization and antimicrobial activity of 1,3,4-oxadiazole bearing 1hbenzimidazole derivatives. arab. j. chem. 10: 503–508 özkay y., tunal y., karaca h. and isíkdag i. 2010. antimicrobial activity and a sar study of some novel benzimidazole derivatives bearing hydrazone moiety. eur. j. med. chem. 45: 32933298. . eajbcs__volume_4_issue_1_article 4_ haftom et al_ synthesis, characterization and antibacterial activity of benzimidazole.pdf (p.48-57) introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction east afr. j. biophys. comput. sci. (2025), vol. 6, issue. 1, 26-32 *corresponding author: email: desie.s@hu.edu.et,+251-916832419 https://dx.doi.org/10.4314/eajbcs.v6i1.3s cattle trypanosomosis and associated risk factors in abala abaya district, wolaita zone, southern ethiopia abera olke1 and desie sheferaw2* 1wolaita zone moard, southern region, ethiopia 2faculty of veterinary medicine, hawassa university, p.o.box 05, hawassa, ethiopia keywords: bovine; buffy coat; glossina; pcv; trypanosomosis; ethiopia abstract cattle trypanosomosis is a unicellular protozoan disease that causes serious economic losses due to its impact on production and productivity. a cross sectional study was done in abala abaya district, wolaita zone, southern region of ethiopia. the study was conducted from november 2023 to april 2024 with the objective of estimating the prevalence of cattle trypanosomosis and assessing the associated risk factors for the occurrence of the disease. systemic random sampling technique was used to select 256 study cattle. buffy coat technique was used to examine for the presence of trypanosoma spp. and to measure pcv of each studied animal. the overall prevalence of cattle trypanosomosis was 18.8% (n=48, 95% ci=14.4-24.0). two species of trypanosoma were identified in area, namely: t. congolense (62.5%) and t. vivax (22.9%). the proportion of t. congolense was significantly higher (p< 0.05) than trypanosoma vivax. the mean pcv of cattle infected by trypanosome significantly (p <0.05) lower than the non-infected cattle. generally, this study revealed that the prevalence of trypanosomosis was higher in abala abaya. further research to explore the prevailing lower overall mean pcv of cattle in the area and timely implementation of different feasible control measures are recommended. introduction ethiopia possessed huge number of livestock population. however, the low economic returns from these resources are associated with several factors such as animal diseases, poor management, and low genetic potential of indigenous breeds (csa, 2022). trypanosomosis is one of the protozoan diseases that puts a significant impediment to cattle production, and negatively influencing the overall growth of agriculture in general; and the nation’s food selfreliance efforts in particular (abebe, 2005). trypanosomosis is a haemoparasitic disease that is caused by unicellular protozoan parasites, genus trypanosoma. trypanosoma species are transmitted either cyclically by glossina spp. or mechanically by biting flies like tabanus spp. and stomoxys spp. (constable et al., 2017; oluwafemi et al., 2007; uilenberg, 1998). in ethiopia, the most commonly reported and predominant trypanosoma spp. include: t. congolense and t. vivax (leta et al., 2016). it reproduces in the bloodstream, lymphatic vessels, and tissue like central nervous system (constable et al., 2017). trypanosomosis is characterized by intermittent fever, progressive east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs research article east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 26-32 27 development of anaemia, and loss of body condition, and if untreated can leads to death of the infected animal (constable et al., 2017; taylor et al., 2007; bourn et al., 2001). animal trypanosomosis is a serious constraint to cattle production, posing a threat to household food security and livelihoods of the community. the disease costs the cattle sector through mortality, reduction in milk production and body weight, and cost of control and treatment (kizza et al., 2021). moreover, trypanosoma spp. influences the ovulatory and oestrous activity (obasi et al., 1999), pituitary function (abebe et al., 1993) and reproduction (ogwu et al., 1984) of cattle. animal trypanosomosis is one of the livestock diseases that impaired cattle productivity in abala abaya district. there is a complaint from livestock owners in the district. therefore, the purpose of the current study was to estimate the prevalence of cattle trypanosomosis, and to assess the potential risk factor predisposing to the infection. materials and methods description of the study area the study was carried out in five selected kebeles of abala abaya, namely: mareka, ajaja, shoya, gafata and faricho. abala abaya district is found in wolaita zone, southern regional state, ethiopia. geographically, the abala abaya district lies between 37°44′10" and 37°54′20" e longitudes and 6°35′0" to 6°45′10" n latitudes. the altitude ranges the district is 700 to 2275 meters above sea level. the average annual rainfall of the area is 854 mm, and the mean annual temperature is 21.9°c. the area is known by mixed farming, crop and livestock, practice, and the community in the area kept livestock that include cattle, sheep, goats and equines. study design the study, a prospective in type, was conducted from november, 2023 to april, 2024. the prevalence of bovine trypanosomosis was estimated, and the potential risk factors were investigated by using a cross-sectional study design. also trypanosoma spp. prevailing in the area was identified. study population the study animals were cattle (i.e. both local and cross breeds) that include both male and female, different age groups and body condition scores. the study cattle were managed under extensive production system. the body condition score of the study animals were grouped in to three: poor, medium and good as described by nicholson and butterworth (1989). their ages were estimated based on teeth dentition (dee fails and magee, 2018) and information obtained from the owners. sample size determination and sampling method the required sample size for the study was computed according to the formula described by thrusfield (2018). for sample size computation expected prevalence of 5% that reported by hundessa et al. (2021) was taken in to account. the computed value was 73 animals, but to increase accuracy of the study this value multiplied by 3.5, and hence, the total sample size of the study was 256 cattle. the study east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 26-32 28 considered 5% desired absolute precision and 95% confidence interval. the study cattle were selected by systematic random sampling (i.e. every 15 cattle were selected) method from purposively selected five kebeles. the study cattle selection was done in the grazing field and in the morning. study methodology sample collection animals selected for study were properly restrained, and the marginal ear vein areas disinfected by 70% denatured alcohol. then it was punctured by using blood lancet and then blood samples were taken with heparinized haematocrit tubes. the blood samples were collected with haematocrit capillary tubes to the level of ¾ of its length and one end of the tube sealed by crystal seal. laboratory examination the laboratory work was done at the site of sample collection by using portable laboratory equipment (microscope, centrifuge, generator, capillary tube, hematocrit reader, microscopic slide, cover slide, blood lancet and field table). on the field, the tubes with blood samples were placed in haematocrit centrifuge with the sealed end kept outward, and then it was centrifuged at 12,000rpm for five minutes. after that the tube taken out of the centrifuge and the packed cell volume (uilenberg, 1998; murray, 1977) was measured by using haematocrit reader and the reading expressed in percentage of the total volume of blood. those animals with pcv less than 24% were considered to be anaemic (oie, 2008). the haematocrit capillary tube was cut by diamond tipped pencil 1mm below the buffy coat (murray, 1977). the content of the capillary tube was then expressed onto a microscopic slide and covered by cover slip. immediately it was examined under 10x and 40x objective lenses to identify the trypanosoma spp. based on the movement pattern of the parasite (oie, 2018; uilenberg, 1998; paris et al., 1982). data management and data analysis collected data summarized by descriptive statistics like mean and percentage. trypanosome infection prevalence was calculated by dividing the number of positive cattle by the total number examined and multiplying by 100. the association of cattle trypanosome infection and the potential risk factors (i.e. sex, age, and body condition score) investigated by univariable logistic regression analysis; and for this purpose stata version 14 software was used for data analysis. results the overall prevalence of cattle trypanosomosis was 18.8% (n=48, 95% ci=14.4-24.0). the analysis of the potential risk factors considered during the study was shown below (table 1). two trypanosoma spp., t. congolense and t. vivax, were in the study district. of the positive cases, nearly 23%, 15% and 62% were because of t.vivax, t.congolense and mixed infection, respectively. east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 26-32 29 table 1: prevalence of trypanosome and univariable logistic regression analysis of the potential risk factors analysis risk factors category no. examined no. positive (%) 95 % ci or χ2 p-value kebele mareka 50 8 (16.0) 8.1-29.1 ref ajaja 51 10 (19.6) 10.8-33.0 1.28 0.47 0.636 shoya 52 10 (19.2) 10.6-32.4 1.25 0.43 0.669 faricho 52 11 (21.2) 12.0-34.5 1.41 0.67 0.505 gafata 51 9 (17.7) 9.4-30.8 1.13 0.22 0.825 body condition good 49 7 (14.3) 6.9-27.3 ref medium 136 21 (15.4) 10.3-22.6 1.10 0.19 0.847 poor 71 20 (28.2) 18.9-39.8 2.35 1.76 0.078 age 1-3 year 87 18 (20.7) 13.4-30.6 1.27 0.63 0.528 4-5 year 94 16 (17.0) 10.7-26.1 ref >6 year 75 14 (18.7) 11.3-29.2 1.12 0.28 0.781 sex male 110 21 (19.1) 12.7-27.6 ref 0.12 0.903 female 146 27 (18.5) 12.6-25.7 0.96 overall 256 48 (18.8) 14.4-20.0 the mean pcv of infected cattle was lower (19.8%) than the mean pcv of non-infected cattle (24.8%) and the difference in mean pcv was statistically significant (p< 0.05) (table 2). table 2. mean pcv value of infected and non-infected cattle conditions no. examined mean pcv (%) se 95% ci t-test p-value infected 48 19.8 0.48 18.8-20.7 12.6 0.000 non-infected 208 24.8 0.32 24.1-25.4 ref. overall 256 23.8 0.31 23.2-24.4 discussion trypanosomosis is negatively influencing the growth of agriculture in general, and particularly the livestock sector. the overall prevalence of cattle trypanosomosis in abala abaya district was 18.8% (95% ci=14.4-24.0%). this observation is agreed with ginta and abegaz (2022) who reported 18.5% (95% ci= 13.123.9). on the other hand the present result is higher than the reports from various areas of southern region of the country (fesseha et al., 2022; seyoum et al., 2022; eyasu et al., 2021; hundessa et al., 2021; takele et al., 2020; girma et al., 2014; begna et al., 2011). higher prevalence of trypanosomosis also reported from southern region of ethiopia (zeryehun and abraham, 2012). these differences in the prevalence of the disease among the studies might be partly related to the variation in ecology, tsetse fly contact with cattle, tsetse fly density and tsetse fly infection rate (gebre et al., 2022; constable et al., 2017; leak et al., 1999; rowland et al., 1993). east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 26-32 30 two trypanosoma spp., namely t. congolense and t. vivax, were encountered during the study in abala abaya district. moreover, t. congolense (62.5%; 95% ci= 47.9-75.1) was the predominant species identified followed by t. vivax (22.9%, 95% ci=13.1-37.1). the predominancy of t. congolense was reported from various areas of the country (gebre et al., 2022; eyasu et al., 2021; tsegaye et al., 2021; teshome and biamesh, 2020; anjulo et al., 2019; leta et al., 2016; fayisa et al., 2015; biyazen et al., 2014; desta et al., 2013; zeryehun and abraham, 2012; daud and molalegne, 2011; abebe, 2005). this might be related the development of better immune response to t. vivax by the infected hosts (taylor et al., 2004; leak et al., 1993). moreover, the predominance of t. congolense in ethiopian cattle is largely due to higher transmission efficiency by tsetse flies, its greater pathogenicity and persistence, suitable environmental conditions, and ongoing vector control strategies. the mean pcv of cattle infected with trypanosome was significantly lower (19.8%; 95% ci=18.8-20.7; p< 0.05) than the mean pcv of non-infected animals (24.8%; 95% ci=24.125.4). this observation is in a general agreement with many authors report (fesseha et al., 2022; kedir et al., 2016; fayisa et al., 2015). this difference could reflect the impact of trypanosomosis on the pcv of infected hosts. lower pcv is one of the symptoms for trypanosomosis (constable et al., 2017). reduction of pcv is an indication of anaemia, which is caused due to erythrophagocytosis, suppressed erythropoiesis and haemaolysis (sudan et al., 2023; akinbamijo et al., 1998). conclusions & recommendations the study revealed that an overall prevalence of cattle trypanosomosis in abala abaya district was higher (18.8%). this could greatly influence the health as well as the productivity of cattle. trypanosoma spp. circulating in the study area includes t. congolense and t. vivax. the mean pcv of cattle infected by trypanosome was significantly higher than the non-infected one. the lower overall mean pcv of cattle in the area need to be further explored and different feasible control measures should be timely introduced in the study area. acknowledgements the author would like to forward heartfelt gratitude to the animal owners for the permission provided to collect peripheral blood sample from their animals. we also extend our sincere appreciation for technical and material support provided by the research team of the step southern project office. references abebe g., 2005. trypanosomosis in ethiopia. ethiopian journal of biological sciences, 4(1): 75-121. http://doi.org/10.4314/ejbs.vi1.39017 abebe g., eley r.m. and kole-moiyoi o. 1993. reduced responsiveness of the hypothalamic-pituitary-adrenal axis in boran (bos indicus) cattle infected with trypanosoma congolense. acta endocrinol. 129: 7580. http://doi.org/10.1530/acta.0.1290075 akinbamijo o.o., bennison j.j., jaitner j. and dempfle l. 1998. haematological changes in n’dama and gobra zebu bulls during trypanosoma congolense infection maintained under a controlled feeding regimen. acta tropica, 69(3): 181–192. anjulo a., alemu b. and yohannes b. 2019. prevalence of bovine trypanosomosis and apparent fly density of tsetse and biting flies in step intervention area of arbaminch zuria wereda. int. j. adv. multidiscip. res., 6(3): 1-8. east afr. j. biophys. comput. sci. 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(eds) the trypanosomoses. cabi publishing, wallingford, oxen ox10 8de, uk. pp. 331-353 taylor m.a., coop r.l. and wall r.l. 2007. veterinary parasitology, 4th edition, john wiley and sons, ltd, the atrium, southern gate, chichester, west sussex, po19 8sq, uk. pp. 1006 teshome z. and biamesh m. 2020. study on bovine trypanosomosis and tsetse identification in south ari woreda of southern nation, nationalities and people regional state (snnprs). thrusfield m. 2018. veterinary epidemiology, fourth edition, blackwell science ltd, oxford, uk pp: 233. tsegaye d., terefe` g., delema d. and tadesse a. 2021. bovine trypanosomosis and its vectors: prevalence and control operations in kellem wollega, western ethiopia. ethiop. vet. j., 25(2): 60-84. uilenberg g. 1998. a field guide for the diagnosis, treatment and prevention of african animal trypanosomosis, fao of united nation, rome, italy. pp. 158 zeryehun t. and abraham z. 2012. prevalence of bovine trypanosomosis in selected district of arba minch, snnpr, southern ethiopia. global veterinaria, 8(2): 168-173. . east afr. j. biophys. comput. sci., vol. 2, issue 1, 64-73 east *corresponding author: email: dagnegetachew@hu.edu.et +251913282529 challenging students’ performance through practical skills assessment in elective football coaching in hawassa university: an action research study dagne getachew1, samuel assefa2, mekoya mengesha3 1 department of sport science, hawassa university, p. o. box 05, hawassa, ethiopia 2 school of teachers education, hawassa university, p. o. box 05, hawassa, ethiopia 3 sport science academy, jimma university, p. o. box 378, jimma, ethiopia keywords: football coaching; practical skill assessment; student’s performance abstract complaints from the university students enrolled in sport science fields or their hiring employers have been heard to practical assessment in sports science. on top of that, long years ofexperience in teaching taught us the problem of practical skills assessment has existed in sports science. this problem emanates primarily from the activities of gross motor parts of the organism while doing sport; leading to a highly subjective assessment. furthermore, the absences of safe and secured facilities for practice, large class sizes, as well as the absence of video materials, to track students’ progress, are among the other factors. this study used the process of action research: identify-plan-act-reflect, in order to improve 3rd year, sports science students' practical assessment skills in elective football coaching at hawassa university. the study participants included 25 randomly selected students from a population of 50 students. football's basic skill first was taught theoretically and practically for the betterment of easy to conduct assessment skills. to do so, the researcher allotted three sessions in consecutive days; after conducting the pre-test assessment. the study has shown that there was a statistically significant increase of difficulty dribbling and trapping the ball from pre-test (m= 1.24, sd= .43) to post-test (m=1.64, sd=.49), t(24)= -4, p<0.005). the eta squared statistics (.4) indicated a large effect size. there was statistically significance increase of control ball with both feet from pre-test (m=2.44, sd= .5) to post-test (m=3.72, sd= .45), t(24)= -8.6, p<0.005). the eta squared statistics (.75) indicated a large effect size. there was statistically significance increase of ability to dribble either direction with token pressure from pre-test (m=2.56, sd= .5) to post-test (m=4.76, sd= .43), t(24)= -17, p<0.005). the eta squared statistics (.92) indicated a large effect size. therefore, from the five parameters of football skill practical assessments, all skill parameters are significant to apply in assessing the psychomotor domain of football in the elective coaching course at hawassa university. the findings revealed that, participation of students in educational assessments are resulted an alteration of training performance in academics. introduction professional skills in sport can be developed through a variety of ways, initiation, qualification, training, specialization, and retraining (gloriaa et al., 2015).this can be realized with suitable assessment among others; east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article east afr. j.biophys.comput. sci., vol. 2, issue 1, 64-73 65 popa et al. (2009) figure out that, formative assessment is powerful effect on stimulate learning and boost up instructional-educational processes. unlike the theoretical assessment in sport science, practical skillassessment should be presented via explaining the skills prior to the formal assessment and even correcting the errors of the performer. because football skills preferred gross motor action, involvement of major large muscle groups: quadriceps femoris and calf muscles. unlike fine motor skills, the involvement of small muscle groups, which enable us to write on the paper and typing a computer. the actions offered by our feet are not accurate. based on popa et al. (2009) observation, they claimed that formative comparatively from others is very powerful and effective in educational-instructional processes. since assessment is perceived as manipulation of instructional-processes, within the scheme professional values are structured, shaping the assessment ability is a necessity to check the work of training and for future teachers, to be stacked with the archive. based on gloriaa et al. (2015) discussed that students are expected to learn verbal and communication skills while they are learning, simultaneously they should be brought with the ability of assessment empirically, and it can empower them to use in their career profession. allowing permanent involvement of the student’s, in the ability of formative assessment skill, bring improvement in their educational objective of the pre-determined outlines. as per the educational formative objective and the instruction, content constitutes the training of assessment skills on the teacher's course description. in ethiopia, dessalegn (2012) tried to bring the experience of teachers in practical assessment skills studied in awi zone, though the designed questionnaire is very vague and difficult to accept by the readers. the same author found out from awi zone's physical education teachers, 43.75% of sport science teachers do not incorporate practical assessment into their lessons, while 56.25% of teachers bring practical assessment every day. the data is not consistent within the study; still, the paradox is going on because of the experience of higher institution sport science teachers. enormous studies have been conducted in theoretical assessment of sport science skills, but limitations of studies are shown in the area of practical assessment skills. the instructional-educational process, as gloriaa et al. (2015)notedin higher education, various competences are developed. among others, praxeological competences are offered in the sport skill pedagogy, training of assessment competence and capacity for the evaluation of practical skills. furthermore, students are permanently considering in the execution of assessment, detecting errors of fellow students and also grading performance. the ideology brought more freedom for the learner, being active in the decision process also. the current research is embedded theoretically to critical action research; problem is identified in the teachers’ work area. action research should be conducted to solve the problem identified via presenting an action plan as remedy. further this thought of action research justified that, philosophically the teachers believe that the normal research is doing on the teacherrather for them (mills, 2014). for instance, students’ are challenged with time east afr. j.biophys.comput. sci., vol. 2, issue 1, 64-73 66 consuming problem solving methods in mathematics, to overcome this problem the mathematics teacher can present a new problem solving strategy. so that, the teacher researcher can writes up the influence of the new intervention. therefore, the purpose of this action research was to improve the subjective nature of practical assessment to make objective in hawassa university 3rd year sports science student's practical assessment skills in elective football coaching. initial reflection based on gamachis et al. (2021) justified that, teachers are working in a more controlled manner, promising to the country’s educational system. the educational policy approach is rigid and inflexible to induce implementation of authentic pedagogical texts. in their study, they have objectively concluded that, practitioner inquiry or action research can present an opportunity to present an immediate solution concerning the problem of teaching learning process. teachers in the school curriculum are mechanized into traditional teaching strategy, incubating a dictatorial socio-educational system in the country. however, instructors in ethiopian public higher institution are working in a more free will environment; they can construct and implement authentic pedagogical texts. from the experience, instructors in sport science have limited their action to conduct an action research to provide a solution for the subjective nature of the courses. they are accustomed with the old saying, assessing the psychomotor domain of sport skills are subjective, traditionally customized themselves. even a blurred vision exists, to differentiate the normal research from the action research. the essence of normal research is simply conducting, administering a questionnaire on the teacher on the other side, the action research bring a solution for the teacher. it is true that, the magnitude and strength of the problemis known by the researcher; prior to conduct the action plan for implementation. in teaching sport science, teachers are overwhelmed by practical skill assessments, because of the subjective nature of the course. as well as the type of serial skills, in which the students are expected to execute different connected skills, this needs the involvement of gross motor skill, at a particular period. movements demanding the involvement of large muscle groups are not accurate; it needs more repetition to perceptualize. thus, the skill should make a vicious circle until it becomes internalize and it may demand the intelligence of the students while the skill is conducted randomly. however, it does not mean that there is no problem in the theoretical class but the practice which is done in the field is more exaggerated, rate of skill assessment. the current sport science courses are classified into indoor and outdoor course delivery. in the first case, the students who are taught indoor or in the gymnasium may not be affected by weather conditions like sun, rain, and windy environment. but outdoor sports activities like football are not conducting in the above environment. so that the level of judgments will be affected because of giving a test at one shot as well as tiredness of both teachers and students, which leads the assessment too much subjective. in this regard, practical skill assessment should be taught first as well as the practicing the assessment should be given east afr. j.biophys.comput. sci., vol. 2, issue 1, 64-73 67 before the actual assessment is started for the improvement of student’s performance. the objective of incorporating “elective sport” into undergraduate sport science curriculum by 2012 is to differentiate the existing sport based on student’s area of interest and alleviating the scarcity of coaches in the country. giving the above fact, majority of graduates in the area of football coaching are complaint on their performance and within a decade action research has not conducted to maximize the objectivity in football assessment. in the light of the above fact, the current researcher tried to induce intervention from the traditional teaching way, because action research in nature oblige the classroom teacher to practice out of the usual locus of control. thus, beyond the usual custom of student’s skill assessment, this research work presented to challenge their performance other than the traditional approach of footballskill assessment. the study was conducted with the objective of minimizing the bias of practical skill assessment after they have been thought by the instructor. more specifically, to reduce the subjectivity of assessment in hawassa university 3rd year sports science student's practical assessment skills in elective football coaching and also enhance the quality of practical skills assessment for the student concerning the mechanics of each technique in football. materials and methods the instrument is developed from with the assumption that, 80% of the goal score is scored from three consecutive passes in football matches (reilly and williams, 2003; reep and benjamin, 1968). the empirical evidence of the previous match analysis conducted by the above authors are agreed and presented for football coaching specialization graduating class of 2019 in hawassa university. in this regard, the current teacher researcher is sliced the football skills into five independent skills in a stations where the student coaches are going to be assessed. they are namely, (1) has difficulty dribbling and trapping ball (2) possesses some ball skills but they are very limited (3) can control ball with dominant foot only (4) can control ball with both feet (5) has ability to dribble either direction with token pressure (6). for instance, the first football skill is “has difficulty dribbling and trapping ball”, while the teacher researcher is administering the skill performed by student coaches. every skills has got measured onto three levels, accurate, partial and inaccurate, it can simplify the rating process at time of football skill assessment. the study preferred a cross-sectional research design, teaching and demonstrating five football skills, they are utilized for a formal assessment. the study was conducted at hawassa university. the study participants included 3rdyear sport science students; from the problem which has been detected on practical skill assessment in elective football coaching. the study participants include 25 (twenty-five) randomly selected student participants from a total of 50 (fifty) students. the study used: pretest and post-test measures, adopting from football skill assessment for individual skills. the study followed four consecutive stages to detect the problem and improving stages namely: (a) initial reflection phasebased on the subject teacher and head department, the problem was identified in practical skill east afr. j.biophys.comput. sci., vol. 2, issue 1, 64-73 68 assessment from the experience of teachinglearning, (b) intervention action plan phasebased on the reflection upon the practical skill assessment from the subject teacher with the head department, and also pre-test will be administered on the respondents, (c) implementation and data collection phaseconducted by higher diploma program (hdp) candidate and followed by post-test were administered (d) analysis of data and reflection phaseincludes discussion and comparison of the pre and post-test findings and reflections on the recommended action. the pre-test has 6 components. results the results of individual assessment for team play is summed in table 1. the skill is provided and prepared with seven variables (explaining football). the weights are allotted based on the difficulty level of the skill assessment. they are divided by five and it can better explain student’s assessment from the point of accurate, partial accuracy, and inaccuracy; 6 & 19, 16 & 9; respectively. this explains, according to the result of pre-test results, they are less accurate while they are executing on difficulty dribbling and trapping the ball. at the time of the posttest, the result is reverted and shown improvement in their football skill delivery to conduct the assessment (table 1). table 1: summary of the results of students’ measures on pre-and post-tests components of individual football skills parameters of assessment pre measurement post measurement difficulty dribbling and trapping the ball accurate. (2) 6 16 partial (1) 19 6 inaccurate possesses some ball skills but they are very limited accurate (3) partial (2) 8 18 inaccurate(1) 17 7 control ball with the dominant foot only accurate (4) partial 19 19 inaccurate (2) 6 6 control ball with both feet accurate (5) partial (3) 11 18 min. (2) 14 7 ability to dribble either direction with token pressure accurate (6) partial (3) 14 19 inaccurate (2) 11 6 nb: the numbers in brackets (2, 3, 4, 5 & 6) are allotted to accurate skill executions based on the difficulty skill levels presented in each football components. for the partial and inaccurate measurement less number was given. east afr. j.biophys.comput. sci., vol. 2, issue 1, 64-73 69 the test consists of 5 football skills, which gathers information about the basics of football. namely: difficulty dribbling and trapping the ball, possesses limited ball skills, can control the ball with the dominantfoot only, can control the ball with both feet and can dribble either direction with token pressure, the weight of each skill are, 2, 3, 4, 5 & 6; consecutively applied on the students. the assessment of football basic skill items was analyzed by dividing the items out of 5 (five). as summarized on table 1, individual football skills on difficulty dribbling and trapping the ball before (pre) and after (post)-test/measurement were 6 & 19, 16 & 9; respectively. this means that the value shown a change in numerical value. similarly, possesses some ball skills but they are very limited, were measured to be 8 & 17, and 18 & 7; at pre and post-test respectively. control ball with the dominant foot only was measured on pre and post-test, from the point of accurate, partial accuracy, and inaccuracy; 19 & 6, 19 & 6, respectively. control ball with both feet was measured on pre and post-test, from the point of accurate, partial accuracy, and inaccuracy; 11 & 14, 18 & 7, respectively. ability to dribble either direction with token pressure were measured on pre and post-test, from the point of accurate, partial accuracy and inaccuracy; 14 & 11, 19 & 6, respectively. action and implementation plan based on the initial reflection phase, hdp candidate designed an intervention to teach a soccer skill for individual assessment, before the assessment they were coached concerning the implementation of the test. for the betterment of the practical assessment, first, they have introduced the concept of peculiar football skills to be examined in the classroom. then they were thought the five soccer skills of the assessment and they will be informed for the practical assessment. in elective football coaching mainly instructors are using to evaluate the capacity of students in the following type of practical skills: (a) difficulty in dribbling and trapping ball, (b) possesses on some ball skills but they are very limited, (c) can control the ball with the dominant foot only, (d) can control the ball with both feet and (e) ability to dribble either direction with token pressure. the first practical skill which is: difficulty dribbling and trapping ball, before the execution of the given skill, will be told how to execute. because in sport there are mechanics on how to manipulate the skill; when they are displaying the skill their heads need to be down and the distance between the feet and the ball, not more than 15 inches. the second football skill is: the ball should be retained via his position and he should protect the ball from the opponents. the third football skill should be: do the students are controlling the ball with the dominant foot only. fourthly, do the students use both feet while he is applying the technique. lastly, students can dribble the ball in either direction with token pressure. findings east afr. j.biophys.comput. sci., vol. 2, issue 1, 64-73 70 in this section, the comparison of students' test scores is presented based on the participants’ pre and post results. figure 1 shows the comparison of pre and post-test for each parametermeasured. either the intervention brought a change also has been assessed, only three a consecutive day of practical training was given for the thirdyear elective football coaching students. figure 1: comparison of pre & post test scores as per the subjectivity of practical assessment, it is the big deal in the academic institutions, however the time for intervention unveil some alteration concerning the psychomotor domains of the subjects. in the process of assessment, students were given five independent but interrelated pieces of soccer skills without demonstration of model or instructors. the subjects were faced challenges to execute and emanate towards the external stimuli, but with the assistance of their classmates they have invariably responded to the test. apparently discussing, scores were taken that is the highest peak among the comparators of accurate, partial accurate and inaccurate. this is because of other factors like the length of engagement in practicing the skill of soccer, method of teaching and limitation of materials. in the time of pretest, students have known the way of execution but unable to associate with the specific type of soccer skills randomly. one of the parameter to assess students were difficulty dribbling and trapping the ball, the pre-test score is maximum, it explicit that the intervention does not show change from the result of post-test. in the soccer skill, dribbling can help us to overcome our opponents even with the maximum number of players are aggregated in the specific area. 0 2 4 6 8 10 12 14 16 18 20 difficulty dribbling and trapping the ball possesses some ball skills but they are very limited control ball with the dominant foot only control ball with both feet ability to dribble either direction with token pressure pre-test post-test parameters of assessment for soccer skill t o t a l m a r k s east afr. j.biophys.comput. sci., vol. 2, issue 1, 64-73 71 however, with the three independent assessors (like, possesses some ball skills but they are limited, control ball with both feet, and ability to dribble either direction with token pressure), the intervention has able to embark some amount of changes in the soccer assessment skills. in the final event that is happened in a steady state is the control ball with the dominant ball only, result is not ubiquitous unlike to the three changed skill of soccer. table 2: summary results of the paired sample t-tests across the 5 measures components of individual football skills mean n sd gm t test p value pair 1 difficulty dribbling and trapping the ball pre 1.24 25 0.436 -0.4 -4* 0.001 post 1.64 25 0.490 pair 2 possesses some ball skills but they are very limited pre 1.32 25 0.476 -0.4 -2.8* 0.009 post 1.72 25 0.458 pair 3 control ball with the dominant foot only pre 2.36 25 0.490 -0.4 -3* 0.005 post 2.76 25 0.436 pair 4 control ball with both feet pre 2.44 25 0.507 -1.28 post 3.72 25 0.458 -8.6* 0.000 pair 5 ability to dribble either direction with token pressure pre 2.56 25 0.507 -2.2 -17* 0.000 post 4.76 25 0.436 * significant (p<0.05), gm= grand mean, sd= standard deviation in general the intervention has resulted change in the academic assessment of students concerning soccer skill assessment. to realize and grasp change, there must be a demonstration before execution of the skill. teachers found in ethiopian public higher institutions, of sport science department can devote ample time for practice and active demonstration can be executed by the instructor for the betterment of assessment. a paired samples t-test was conducted to evaluate the impact of assessment on student’s score in football skill assessment. there was statistically significance increase of difficulty dribbling and trapping the ball from pre-test to post test (p<0.005). the eta squared statistics (0.4) indicated a large effect size. there was statistically significance increase of possesses some ball skills but they are very limited from pre-test to post test (p<0.009). there was statistically significance increase of control ball with the dominant foot only from pre-test to post test (p<0.005). there were also statistically significance difference in the other components of individual football skills. there was an increase of control ball with both feet from pre-test to post test east afr. j.biophys.comput. sci., vol. 2, issue 1, 64-73 72 (p<0.005). the eta squared statistics (0.75) indicated a large effect size. there was also statistically significance increase of ability to dribble either direction with token pressure from pre-test to post test (p<0.005). the eta squared statistics (0.92) indicated a large effect size. discussion and conclusion according to mills (2014), a written account concerning the classroom life experience is important; it can be a record for professional and personal use. in this regard, the researcher has not found resemble literatures which can be used as a stepping board to show the agreement and disagreement of the action research. the finding of the study is supported by fitts’ stage theory of motor learning, developed by different authors (schmidt and lee, 2005, abernethy, 2001; anderson, 1982). as noted by fitts’ model, there are three stages learners can go through, cognitive, associative stage and autonomous stage. in the cognitive stage, elective students should be taught about the rules and verbal instructions of the selected football skills. the session can provide an opportunity to the learners or they are free will to practice with different errors. in the second stage, candidates can easily associate with every pattern of skill and be consistent. finally, more practice is presented for the learner can maximize their performance and execute with minimal error. one of the main challenges in sports science coaching practice is how to evaluate the practical performance of students, owing to the absence of standard parameter used for assigning grades. football instructors are using different approach and rating system to measure the performance of football coaches. in this regard, this action research identified a problem in elective football coaching course, designed an intervention of teaching on the given assessment contents in practical sessions; they have provided with how the content measured and also the pattern of each skill practiced. students had open discussion opportunities to deal with the psychomotor domain of the subject; practiced prior to the main assessment sessions. a few elite footballers’ has the capability to play in both feet, but in executing an assessment there must be teaching the technique of football and students should be informed. the experience is different in assessing the theoretical domain of football amid fear of mark inflation. thus, in practical assessment, the pattern of test should be provided to the student’s. in this way, the subjectivity of objectivity can be decreased and customer’s satisfaction can be achieved. in general, the study revealed that there is a significance difference in all variables of football skill practical assessment. in football learning, dribbling is difficult to catch easily from the coaches or trainers even at the time of assessment. but if dribbling with trapping the ball may be taught prior to the actual assessment, the performance of elective students can be escalated. during the attachment phase, they have shown progress in their individual football skills practice in addition to the direct measurement of their performance. based on the findings, the researcher concludes that, students’ need to be learned the contents and assessments both theoretically and practically. east afr. j.biophys.comput. sci., vol. 2, issue 1, 64-73 73 study limitations the study has limitation pertaining the limited number of variables, area coverage and sample size (number of participant, representativeness, year of graduates). moreover, instead of approaching the most fragmented skill individual assessment, an integrated assessment developed by team of professionals may need further investigation. acknowledgement special thanks should be given for the graduate class of 2019 sport science students for their willingness to participate in the research. though the paper is not funded by any organization, for the accomplishment of this mini version; kudos for the hdp supervisors of hawassa university for their assistance without reservation. this contribution may not be realistic without creating an opportunity by teaching higher education. references abernethy b. 2001. acquisition of skill. in f.s. pyke (ed.), better coaching: advanced coach’s manual (2nded.). lower mitcham, australia: human kinetics. pp. 161-170 anderson j.r. 1982.acquisition of cognitive skill.psychological review 89: 369-406. dessalegn, a. 2012. the practice and challenges of continuous practical physical education assessment at awi zone preparatory schools (published m.a. thesis). addis ababa university. gamachis b., dereje t. b., adinew t. d., abera a. and alemayehu g. 2021. teachers‘ concerns and policy suggestions for bridging the wide gaps between policy ambitions and classroom practices in ethiopian teacher education system, ethioinquiry journal of humanities and social sciences 1(1): 62-76. gloriaa r., constantin r. b. and marinelac, r. 2015.training of students' practical assessment ability in physical education and sports science. elsevier. procedia social and behavioral sciences 180 1311 – 1315. mills g. e. 2014. action research a guide for the teacher researcher (5thed.). england and associated companies throughout the world. pearson education limited. edinburgh gate harlow essex cm20 2je popa n. l., antonesei l. and labăr a. v. 2009.ghid pentrucercetareaeducaţiei.[a guide for educational research] pentrustudenţi, masteranzi, profesori, 31,iaşi: polirom. reilly t. and williams a. m. 2003. science and soccer.(2nded). routledge 11 new fetter lane, london ec4p 4ee. usa and canada schmidt r.a. and lee t. 2005.motor control and learning: a behavioral emphasis (4thed.). champaign, il: human kinetics. united states of youth soccer association [usysa].(2000). how to assess soccer players without skill tests. tom turner, oysan director of coaching and player development . cover v2.pdf (p.1) cover.pdf (p.1-2) slide number 1 blank page.pdf (p.2) table of contents vo 2.pdf (p.3-5) all articles vol 2.pdf (p.6-81) volume 2 issue 1_ 6 articles_4_3.pdf (p.6-91) 4_captive fish_anna results and discussion references 3_reproductive disorder 6_diet bredth_prof. nat 8_ground water_jeeva base boundary map was prepared using survey of india topo-sheets of the study area, and data such as rainfall, geomorphology, geology and land use were collected from central and state government agencies. during field study, groundwater samples were ... 10_ethnoveterinary following comments dagne et al_ challenging students’ performance through practical skills assessment.pdf (p.73-82) back cover.pdf (p.91) introduction extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction introduction east afr. j. biophys. comput. sci. (2024), vol. 5, issue. 1, 13-24 thando tenza1*, lindokuhle christopher mhlongo2, cypril ndumiso ncobela3 and zikhona rani1 1 animal and poultry science, school of agricultural, earth and environmental sciences, university of kwazulu-natal, p bag x01 scottsville 3209, pietermaritzburg, south africa 2 department of animal science, university of the free state, bloemfontein, south africa. 3 department of agriculture, faculty of natural sciences, mangosuthu university of technology, p. o. box 12363, jacobs 4026, south africa keywords: contribution; income; livelihoods: sustainability; training; vending abstract the study aimed to determine the contribution of the informal market of village chickens to sustainable livelihoods. the study was conducted in two purposively selected cities namely durban and pietermaritzburg, kwazulu-natal, south africa, central business district (cbd). a questionnaire was administered to village chicken vendors in the cbd. a total of 50 village chicken vendors which were limited in the cbd, were found and interviewed. in both durban (100%) and pietermaritzburg (77%), the majority of village chicken vendors were women (p<0.05). village chicken vendors depended on selling chickens and vending other commodities in both cities (p>0.05) to generate income (100%). none (0 %) of the village chicken vendors were exposed to chicken farming training on village chickens in durban and 11% in pietermaritzburg have been exposed to training (p<0.05). over 85% were interested in attending chicken farming training in both areas. there was a significant difference (p<0.05) between the main source of income and the uses of chickens. the use of village chickens influenced the main source of income, which was not limited to income generation or leisure. it was concluded that the informal market for village chickens contributes to sustaining livelihoods through income, consumption and culturally driven. it is recommended that access to training and resources can grow the informal market. introduction in 2050, the world population is expected to increase by at least 2.5 billion (galimova et al., 2022) and the demand for animal protein will also increase drastically. this suggests creating traditional markets using untapped animal resources such as village chickens for protein alternatives. using underutilized animal resources through informal village chicken vending may prevent insufficient conventional protein sources in developing countries that may come with population increase. there has been a east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx contribution of the informal market of village chickens to sustainable livelihoods in kwazulu-natal, south africa *corresponding author: email: tenzathando7@gmail.com +27844727930 https://dx.doi.org/10.4314/eajbcs.v5i1.2s research article east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 14 growing interest in investigating informal market village chicken in response to the agenda of sustainable development goals. informal village chicken vending refers to producing and selling legal goods and services in urban public spaces in temporal structures (recchi, 2021). there is a great potential for informally vending village chicken, especially for vulnerable groups in resource-poor settings. since the informal sectors are mostly ignored or unsupported by the government, individuals are discouraged to participate in this sector (brown, 2006). the informal market of village chicken has the potential to contribute immensely to achieving specific sustainable development goals (sdgs), such as no poverty (sdg1) and zero hunger (sdg2), particularly for the vulnerable group if the correct measures are taken (wilson et al., 2021). achieving sdg2 in sub-saharan africa is challenging as the population is rapidly growing, which demands a large amount of animal proteins. village chicken (gallus domesticus) production in africa is practiced in rural communities (boudali et al., 2022). in south africa, individuals mostly own village chickens based in resource-poor settings commonly known as rural areas. their major role in these areas is to provide animal protein through eggs and meat which are crucial for income generation through sales (elsiddik, 2022). village chickens are also crucial for traditions and rituals of different ethnicities. however, the production of village chickens is hampered by various challenges, including a high mortality rate, disease prevalence, poor technical support, predation, theft, and poverty. they are reared under an extensive production system with a flock size of less than 100 that depends on scavenging for feed resources (chowdhury, 2013). this system is characterized by low input and low output as there are no or minimal inputs such as housing, feeding, and health control, resulting in a high mortality rate that reduces the flock size. village chickens are primarily bred and reared for meat, eggs, cultural practices and income to contribute to family consumption (mujyambere et al., 2022). considering the poor socio-economic status and food and nutrition insecurity in resource-poor settings of kwazulu-natal, south africa, solutions and recommendations are needed by communities. village chicken vendors are selling village chickens in the central business district for income and they are very scarce. understanding the dynamics of the village chicken informal market is important to identify gaps and challenges to provide appropriate interventions. this study aimed to assess how the informal market of village chickens contributes to sustainable livelihoods in kwazulu-natal. it was hypothesized that village chickens do not contribute to the informal market for sustainable livelihoods. materials and methods study area the study was conducted in pietermaritzburg as shown in figure 1, which is the capital city of umsunduzi municipality within the province of kwazulu-natal. it is located on the tropical eastern coast of south africa (nicolson, 2010). east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 15 figure 1:geographical map of kwazulu-natal the study sites in durban and pietermaritzburg cities pietermaritzburg (29°37′s 30°23′e) experiences summer rainfall and a warm and temperate climate. the average annual rainfall is 865.3 mm, with average maximum temperatures ranging from 22.6°c to 24.5°c and minimum temperatures ranging from 9.9°c to 16°c. the current population is estimated to be over 600,000 residents in pietermaritzburg. figure 2: village chicken vendors with cages (a and b) in pietermaritzburg central business district. interviewing village chicken vendors (c) chicken cages in durban central business district (d) durban is a major coastal city on the eastern coast under ethekwini metropolitan municipality in south africa. the city also known as a tourist venue (koopman, 2012). the central business district is located adjacent to the harbor which is the most important contributing factor to the city's economy (timm, 2011). durban (29°53′s 31°03′e) has an annual a b c d east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 16 rainfall of 1,009 millimeters and the average temperature in summer is around 24 °c, while in winter the average temperature is 17 °c. the durban suburbs and neighboring towns have a population of about 3.44 million. table 1.the description of the data source of village chicken vendors variable description reason for the information request demographic data owners of the chickens, gender of the owners and age distribution identifying participants in the traditional market of village chickens income sources village chicken keepers evidence on the level of dependency on village chickens reason for selling village chickens options such as income and food indicate the objectives of village chicken vendors which influence the willingness to participate in this system. the duration of selling village chickens years in the central business district the number of years to indicate the time in years spent participating in the market targeted population group race that should buy the chickens the type of population group targeted for this informal market the population group that frequently buy the race that buys the most the population group that responds to the informal market of village chickens type of feed for village chickens feed type to understand what they are feeding chickens in cages the duration of village chickens in the cage how many hours do village chickens spend in cages to understand and identify the animal welfare of village chickens in the informal market the type of knowledge the type of knowledge systems used the type of knowledge used is important to understand the rearing system the uses of different breeds type of breeds and functions the function of different types of breeds statistical analysis all data were analyzed using sas (2011). all demographic characteristics in durban and pietermaritzburg were analyzed. the association was measured using chi-square tests between demographic parameters. the proc freq /chisq test was used. = . ∗ cramer's v was used to measure and examine the strength of the association between two variables using the following model: v= x2 = is the chi-square value df*=min (r-1, c1) and r= the number of rows and c=the number of columns in the contingency table and n=the total sample size. results description of village chicken vendor's demographics the participants (i.e. village chicken vendors in both pietermaritzburg and durban) interviewed were women and men over 18 years of age. the gender of village chicken vendors had a significant difference (p<0.05) in both cities as east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 17 more females were participating in vending village chickens compared to men. in durban, all (100%) village chicken vendors were female, and 77% of vendors in pietermaritzburg were female. the age of village chicken vendors ranged from 40 to 50 years (62%) and 50 to 60 years (26%) were common (p>0.05). in durban, 32% of village chicken vendors have participated in the informal market for over 30 years (p<0.05) in pietermaritzburg. their source of income included vending of chickens, vegetables and pension, as shown in (table 2). table 2.the demographic of the informal market village chicken vendors in durban and pietermaritzburg central business district demographic characteristics durban% pietermaritzburg% p value gender of the trader female 100 77 * male 0 23 age of the trader (years) 20 to 30 16 0 ns 30 to 40 21 15 40 to 50 21 62 50 to 60 26 15 60 to 70 16 8 duration of trading (years) less than 5 21 13 * more than 5 5 41 more than 10 21 28 more than 20 21 15 more than 30 32 3 the major source of income vending other commodities 47 54 ns pensioner 0 0 vegetables 0 8 chickens 53 38 purpose of selling income 100 100 ns barter exchange 0 0 leisure 0 0 training of village chicken vendors training attended not attended training 0 100 11 89 * interest to attend no interest in attending 85 15 95 5 * access to extension officer 8 5 no access to extension officer 92 95 * ns = not significant (p > 0.05), *significant(p < 0.05) east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 18 in pietermaritzburg, more than half of the participants (54%) depended on vending other commodities; in durban, 53% relied on vending village chickens. a total of 100% of village chicken vendors relied on vending village chickens for income generation in both areas while none was selling for barter exchange and leisure. the importance of knowledge to village chickens figure 4below indicates different types of knowledge used in rearing village chickens for income generation. village chicken vendors depended greatly on indigenous knowledge (89%), followed by the combination of indigenous and scientific knowledge (10%) and lastly, scientific knowledge (1%). the results (table 2) indicated that only 11% of village chicken vendors received training with 95% willingness to attend in pietermaritzburg. less than 10% of extension officers were available for village chicken vendors to provide knowledge in durban and pietermaritzburg. figure 4: the knowledge used by village chicken vendors in the village chicken markets consumers of village chickens by population group figure 5 below indicates the population group that purchases village chickens largely. all population groups were targeted to buy village chickens. results suggest that africans (82%), followed by asians (2%),were the predominant consumers of village chickens. village chicken vendors showed a significant difference (p<0.05) in the preferred chickens to sell in both durban and pietermaritzburg. live chickens (98%) were preferred over cooked meat (2%). -40% -20% 0% 20% 40% 60% 80% 100% 120% 140% indigenous knowledge scientific knowledge indigenous knowledge & scientific knowledgen um be r of v ill ag e ch ic ke n ve nd or s (% ) type of knowledge use by village chicken vendors east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 19 figure 5.the consumers of village chickens in both durban and pietermaritzburg type of village chicken breeds for cultural practices. figure 6 below indicates the type of village chicken breeds sold by village chicken vendors and breeds in demand in the market. potchefstroom koekoek (impangela) is the most sold breed (97%), followed by boschveld (ezibomvu) (94%), black australorp (ezimunyama) (75%) and broilers (ezimhlophezesingisi) (72%). results in figure 6 showed that there were breeds demanded in the market such as potchefstroom koekoek (impangela) (69%) and boschveld (ezibovu) (69%). durban and pietermaritzburg village chicken breeds have various purposes in the informal market regarding cultural practices. each breed has its specific function in communicating with ancestors in these areas. figure 6. breeds sold and in demand in the village chicken market 0% potchefstroom koekoek/(impangela) boschveld /(ezibovu) black australorp /(ezimnyama) white leghorn chickens/(ezimhlophe) ovambo chickens/(umbala oxubile) venda chicken breed/(ezigreyi) broilers/ (ezimhlophe zesingisi) type of breeds sold and breeds in demand type of breeds in demand east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 19 figure 5.the consumers of village chickens in both durban and pietermaritzburg type of village chicken breeds for cultural practices. figure 6 below indicates the type of village chicken breeds sold by village chicken vendors and breeds in demand in the market. potchefstroom koekoek (impangela) is the most sold breed (97%), followed by boschveld (ezibomvu) (94%), black australorp (ezimunyama) (75%) and broilers (ezimhlophezesingisi) (72%). results in figure 6 showed that there were breeds demanded in the market such as potchefstroom koekoek (impangela) (69%) and boschveld (ezibovu) (69%). durban and pietermaritzburg village chicken breeds have various purposes in the informal market regarding cultural practices. each breed has its specific function in communicating with ancestors in these areas. figure 6. breeds sold and in demand in the village chicken market africans asians 0% 10% 20% 30% 40% 50% 60% 70% 80% potchefstroom koekoek/(impangela) boschveld /(ezibovu) black australorp /(ezimnyama) white leghorn chickens/(ezimhlophe) ovambo chickens/(umbala oxubile) venda chicken breed/(ezigreyi) broilers/ (ezimhlophe zesingisi) type of breeds sold and breeds in demand type of breeds in demand type of breeds sold east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 19 figure 5.the consumers of village chickens in both durban and pietermaritzburg type of village chicken breeds for cultural practices. figure 6 below indicates the type of village chicken breeds sold by village chicken vendors and breeds in demand in the market. potchefstroom koekoek (impangela) is the most sold breed (97%), followed by boschveld (ezibomvu) (94%), black australorp (ezimunyama) (75%) and broilers (ezimhlophezesingisi) (72%). results in figure 6 showed that there were breeds demanded in the market such as potchefstroom koekoek (impangela) (69%) and boschveld (ezibovu) (69%). durban and pietermaritzburg village chicken breeds have various purposes in the informal market regarding cultural practices. each breed has its specific function in communicating with ancestors in these areas. figure 6. breeds sold and in demand in the village chicken market 80% 90% 100% east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 20 table 3 shows the level of association in two variables of village chicken vendors in both durban and pietermaritzburg. the results indicated a strongest (0.64) insignificant association between type of breed in demand and the reason for breeds in demand.. in addition, the association between gender and age was the weakest (0.28). there was a significant difference (p<0.05) between the major source of income and the uses of chickens. the lowest association compared to the breed type in demand and reasons for breeds in demand was insignificant (p>0.05). table 3. the strength of associations on village chicken vendors in durban and pietermaritzburg associations cramer's v p value gender * age 0.28 ns duration of selling * major source income 0.30 ns the major source of income * uses of chickens 0.60 * type of chicken preference * reasons for preference 0.33 ns type of breed in demand * reasons breeds in demand 0.64 ns cramer's v is -1 ≤ v ≤1 where -1 is the weakest and 1 is the strongest association. important information, recommendations and questions from village chicken vendors village chicken vendors rent for r250 to the municipality monthly to sell village chickens in the central business district. a total of 100% of village chicken vendors feed yellow maize grain to village chickens daily in cages with 70% buying and 30% planting their maize. village chickens in cages were housed for 24 hours daily until one is sold to the customer, with the flock size ranging from 10 to 20 chickens per cage. village chicken vendors only sourced chickens from village chicken producers if funds were available. results indicated that a cock costs an average of r100 and a hen is r70 depending on the breed. village chicken vendors sell village chickens in conjunction with crop seeds, sweet potatoes and herbal plants. they were interested in receiving training in poultry management. concerns about how the government can provide a market for village chickens were observed. questions on who to consult regarding village chickens were populated predominantly in durban compared to pietermaritzburg. discussion in the current study, the majority of village chicken vendors were women compared to men. this is in line with (chawala, 2022), who reported that the value chain of village chickens is mainly dominated by women and is regarded as a women's value chain. similar results of oguttu (2015) indicated that the majority of vendors of chickens are females between the age of 25-50. on the other hand, it is proven that in south africa, village chickens play a significant role socially, traditionally and economically but this niche is underutilized and poorly managed. simbizi et al. (2022) stated that village chickens were of benefit in south africa but the sector is underdeveloped. it is evident in the study areas that village chicken vendors depend on indigenous knowledge when rearing village chickens. gunya et al. (2020) indicated that there is less or no information available on village chicken production and their contribution to south africa. the vending of village chickens in the central business east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 21 district of the two largest cities is an indication that there is a market for village chickens that the policymakers do not recognize in kwazulunatal. in contrast, in the eastern cape, south africa, gunya et al. (2020) showed that farmers are not selling village chickens because there is no market for these types of chickens. meanwhile, assefa (2019) suggested that the domestic market of village chickens through sales of both chickens and eggs creates the opportunity to generate income in ethiopia. in south africa, the country faces challenges such as high unemployment rate and low-skilled communities. as shown in the study, the major source of income of these farmers is vending various commodities in the cities. street vendors have the potential to build a livelihood and contribute to the economy (hlengwa, 2016). the findings demonstrated that individuals in resource-poor communities resort to the vending of village chickens for more than 30 years of their lives as the main source of income. as indicated by reinecke and white (2004), street vending is growing rapidly in developing countries as a response to poverty. this concurs with the current study that the purpose of vending village chickens was for income generation which were used in the homestead for needs such as school fees, groceries and transport. musa (2022) argued that religion and cultural practices are the other reasons for rearing village chickens. at the same time, village chickens are regarded as the primary source of investment for both women and children (mujyambere et al., 2022). idamokoro and hosu (2022) suggested that sales are the only way to generate income through village chickens. the present study stated that there were no extension services from the government and other institutions to assist with scientific knowledge on how to rear village chickens correctly. lee et al. (2022) revealed that gender inequalities concerning less access to extension services for women have been corrected. the finding that most village chicken vendors depend largely on indigenous knowledge to rear and grow village chickens was expected because formal information or scientific knowledge is not available and accessible. indigenous knowledge is referred to as philosophies created by societies with long histories of interaction with their natural surroundings (rogelj et al., 2018). the findings of the current study revealed a strong connection between gender and age of village chicken vendors, as women were shown to be the most populated group in this market. in sub-saharan africa, over 70% of village chicken owners are female and assisted mainly by children and other women (guèye, 2000). on the other hand, the duration of selling village chickens and the major source of income were less connected since there were different ways of creating income rather than selling chickens such as vending other commodities. in developing countries, street food vending has become one of the sources of income (mwangi et al., 2002). hence, the current study suggests selling village chickens can be more significant as a major source of income if correct measures such as management and training were provided to village chicken vendors. the study found that village chicken vendors were interested in selling uncooked and cooked meat, but most preferred selling live chickens. however, manickavasagam (2018) indicated that various products such as fruits, vegetables, shoes, newspapers and magazines were also sold by vendors. but regarding the current study, vending of village chickens had its challenges as cages, slaughtering rooms, stoves to cook, load shedding and low demand for these products. however, village chicken vendors were open to the idea that assistance could be provided. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 22 in the study, village chickens were accessible to every population group but africans and pakistanis living in south africa were the frequent consumers of this product. africans use village chickens primarily for cultural practices and pakistanis use them for consumption. unathi et al. (2017) argued that the demand and consumption of village chickens in south africa is unknown. village chicken vendors suggested that village chickens were sold according to breed and breeds in demand for cultural purposes beneficial to the business. for instance, potchefstroom koekoek (impangela) is essential for ancestral ceremonies while black australorp (ezimunyama) is used for traditional cleansing. most village chicken vendors made high profits from these breeds and there was a strong connection between breeds sold and breeds in demand. in the current study, village chicken vendors were invested in selling village chickens and interested in producing for themselves while learning more about poultry. but queries and worries such as seeking government assistance were indicated. the biggest challenge was there is no formal market and relevant stakeholders are required in addressing issues and interventions to formalise the existing market. these challenges also include storage as village chickens are stored and confined in cages. for 24 hours daily with a high stocking density. this is a welfare issue as village chickens are scavengers by nature they need to roam around and look for feed resources. this indicates a lack of relevant knowledge and a violation of the five freedoms of animal husbandry but this scientific knowledge is not available to individuals in resource-poor communities. high stocking density in a small cage for so many hours results from a lack of knowledge. increasing stocking density can encroach on chicken's freedom to express natural behaviour (tallentire et al., 2019). they must exercise their natural behaviour like to roam around and scavenge for feed. village chickens obtain most of their diet by scavenging for both food and water (gunya et al., 2020). tenza et al. (2023) suggested the development of programs focusing on village chickens for livelihood transformation and women empowerment in resource-poor communities. in the study, village chickens were provided with maize once or twice per day depending on the sales and profit because buying maize was a challenge. the vendor complained about the price and resorted to restricting feeding chickens to avoid buying more frequently. depending on one nutrient source may affect the quality of the meat as other nutrients were limited since village chickens were caged for 24 hours. gondwe and wollny (2007) showed that village chickens scavenge naturally, and most farmers used maize as a feed supplement. the market price for chickens was discussed among each other to avoid losing customers and contradictions. therefore, prices were uniform but depended greatly on the size and type of breed sold. however, no digital scale was available to measure the size of the chicken, so visual observations were used. this is in line with tilahun et al. (2022) who argued that the price of village chickens was influenced by body size and plumage. similarly, village chickens are considered a high-quality product sold at a higher price (selamat et al., 2022). other village chicken vendors sold both broilers and village chickens, and the demand was the same in the market. broilers were significantly added as substitutes if sales for village chickens were low. in the current study, the vendor's preference for village chickens was due to low inputs such as terms of feed, compared to broilers. this is similar to alam et al. (2020) who revealed that village chickens are always preferred due to their low production cost as they are reared through scavenging of feed resources. vending chickens in conjunction with other indigenous east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 13-24 23 herbal plants was significantly suggested for income generation in case there were no chicken sales. the study revealed the eagerness of vendors to attend training on village chickens to improve productivity and disease control, improve knowledge, and expand the business. conclusion & recommendations the study concludes that village chicken vendors use village chickens to sustain livelihoods in kwazulu-natal, south africa. even though the market is populated by women from youth, adults and old age. the market has existed for over three decades and plays a role for vulnerable groups in resource-poor settings. village chickens are mainly sold for cultural practices as certain breeds are in demand compared to others. the considerable challenge is the lack of support from different stakeholders to allow the informal market in the main scream value chain as it benefits individuals who lack skills, are unemployed and suffer from hunger. it is recommended that organizations are needed to offer training and provide resources to grow the informal market of village chickens that are located in big cities. this has the potential for a more significant impact and influence on policy. it is also recommended to use underutilized products such as village chickens in achieving the 2030 vision such as sdg 1 and 2, in resource-poor communities as they lack skills and opportunities. conflict of interest authors declare no conflict of interest. ethics statement the study was conducted based on the standards required by the human social science ethics committee of the university of kwazulu-natal (hssrec/00004846/2022). acknowledgment the authors would like to acknowledge the sustainable and healthy food systems (shefs) program of the welcome trust's our planet, our health program [grant number: 205200/z/16/z] and foodbev seta bursary. references alam m., ullah m. o., malik s. u. f. and islam m. s. 2020. broiler and indigenous chickens: a comparison through biochemical parameters. int. j. sustain. agric. res.7: 228-233. assefa h. 2019. the role of poultry for poor livelihoods in ethiopia. int. j. vet. sci. anim. husb. 4: 1-4. aye k. and sarma b. 2022. street vending and urban public space: a study of street vendors in beltola market, guwahati. int. j. health sci. 6(s8): 150– 172. https://doi.org/10.53730/ijhs.v6ns8.9667 boudali s. f., al-jumaili a. s., bouandas a., mahammi f. z., tabet aoul n., hanotte o. and gaouar s. b. s. 2022. maternal origin and genetic diversity of algerian domestic chicken (gallus gallus domesticus) from north-western africa based on mitochondrial dna analysis. anim. biotechnol. 33: 457-467. brown a. m. b. 2006. contested space: street trading, public space, and livelihoods in developing cities, itdg publishing. https://doi.org/10.3362/ 9781780444703 chawala m. 2022. investigating the relationship amongst business development services, entrepreneurial orientation and commercialisation intention of smallholder farmers of indigenous chickens–a theory of planned behaviour approach. copperbelt university. chowdhury s. 2013. family poultry production in bangladesh: is it meaningful or an aimless journey? worlds poult sci j. 69: 649-665. elsiddik a. f. o. 2022. assessment of management intervention on improving productivity of indigenous chicken in rural households, alhiglig village, gezira state, sudan. university of gezira. galimova t., ram m. and breyer c. 2022. mitigation of air pollution and corresponding impacts during a global energy transition towards 100% renewable energy system by 2050. energy reports 8: 1412414143. gondwe t. and wollny c. 2007. local chicken production system in malawi: household flock structure, dynamics, management and health. trop. anim. health prod. , 39: 103-113. east afr. j. biophys. comput. sci. 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(2023), vol. 4, issue. 2, 13-30 *corresponding author: email: danielfitamo@gmail.com, +251-911996720 https://dx.doi.org/10.4314/eajbcs.v4i2.2s assessment of healthcare solid waste composition, generation and its management: the case of two hospitals of shashemene town, oromia regional state, ethiopia gudeta elie, daniel fitamo and semere gebreaegawi* department of biology, hawassa university, ethiopia keywords: health care waste; general waste; hazardous waste; hcw management; solid waste generation abstract hazardous wastes from hospitals could pose threat to the health of healthcare workers, the general public and the environment unless managed properly. the study aimed to appraise the healthcare waste (hcw) composition, generation rate and the prevailing management practices in two hospitals (a private and a government owned) of shashemene town, ethiopia. a cross-sectional study involving direct observation, key informant interview, questionnaire survey and weighting scale was conducted to evaluate the current hcw management practices and to quantify the hcw generation rate. data was analyzed using spss version 20. the mean generation rates of hcw were 45.2 ± 5.8kg day–1 (0.20kg bed‒1day‒1) and 20 ± 2.4 kg day–1 (0.19kg bed‒1day‒1) from government hospital (gh) and private hospital (ph), respectively. of the total solid waste generated, over half (gh: 53.3%; ph: 57.1%) constituted general waste (gw), and the remaining (gh: 46.7%; ph: 42.9%) comprised hazardous waste (hw), which exceeded the who threshold (10‒25%) intimates the lack of poor waste segregation. there were significant variations between the hospital wards regarding gw (gh: χ2 = 31; p < 0.001; ph:χ2 = 13; p < 0.01), hw (gh: χ2 = 25; p < 0.001; ph: χ2 = 10; p < 0.01), and total hcw (gh: χ2 = 46; p < 0.01; ph: χ2 = 22; p < 0.01). besides, significant differences were observed between the mean total hcw (χ2 = 9.016;p < 0.01), gw (χ2 = 9.8; p < 0.01) and the hw (χ2 = 5.011, p < 0.05) of the hospitals. segregation of wastes and pre-treatment of infectious wastes were not properly practiced, and single chamber incinerators was the most utilized treatment method indicating poor management of the hcw. the study establishes that the little attention is given to medical waste management which primarily proceeds from a lack of due implementation of the national healthcare wastes management guideline/directive at the healthcare facility level. if the poor healthcare solid waste management is not properly addressed at the study hospitals, human (healthcare workers, waste handlers, patients, and nearby community) and environmental health risk will be within the bounds of possibility. introduction healthcare activities are means of protecting health, curing patients, and saving lives (debere et al., 2013). hospitals are among the complex institutions which generate a broad range of hazardous waste materials in the course of healthcare activities (farzadkia et al., 2009). healthcare waste is a major problem in most developing countries of the world due to its growing and endless east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 14 generation coupled with poor management (abd el-salam, 2010). healthcare waste contains a large component (75‒90%) of nonrisk or general healthcare waste, comparable to municipal solid waste (msw) and a smaller component (10‒25%) of hazardous waste may pose a variety of health risks (who, 2014). the process of collecting, storing, transporting, treating and disposing waste material is known as waste management (alkhatib and sato, 2009). improper waste management in which the infectious waste is mixed with the general waste can lead to the entire bulk of the wastes becoming potentially infectious. it is well known that inappropriate hospital waste management is pressing both health hazards and environmental pollution, facing many healthcare centers of this developing world (bdour et al., 2007). diseases like cholera, dysentery, skin infection, and infectious hepatitis can spread epidemic way due to the mismanagement of hospital solid waste (coker et al., 2009). therefore, it is urgent to determine appropriate methods for the safe management of hospital solid waste. uncontrolled combustion of medical waste accounted for 26% of the annual total dioxins / furans release in 2003 in ethiopia (eepa, 2006). recently, considerable gap exists with regard to the assessment of healthcare solid waste management practices in ethiopia. unfortunately, relevant information on this important aspect of healthcare management is inadequate and research on the public health implications of inadequate management of healthcare solid wastes are few in number and limited in scope (habtetsion et al., 2009). ethiopia is signatory to the stockholm convention on persistent organic pollutants (pops), which is a global convention with the aim of eliminating some of the most long‐lived anthropogenic pollutants (unep, 2009). while studies illustrate the solid waste menace in the ethiopian towns and cities, the data on health care solid waste remains in huge paucity both at regional and national level. the present study, therefore, attempted to determine the healthcare solid waste composition, generation rate as well as evaluate its management systems in two selected hospitals of shashemene town, oromia region materials and methods description of the study area shashemene town is the capital of shashemene woreda (district) in west arsi zone of oromia regional state, ethiopia. it lies on the trans-african highway of cairocape town, about 250 km from the capital of addis ababa. the town is located at latitude of 7° 12' north and a longitude of 38° 36' east. in shashemene woreda, there are teaching and referral (shashemene referral hospital), and private (feya general hospital) hospitals providing services for more than 122,046 people. shashemene referral hospital has a total of 240 beds with an average patient’s flow of 282 patients/day providing cafeteria, emergency, general medicine, family planning, laboratory, leprosy, tb and malnutrition, epilepsy and psychiatry, ophthalmic, pediatrics, surgical, pharmacy, and inpatient services. feya general hospital is private owned hospital and the hospital is engaged in providing east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 15 diagnostic and medical treatment in addition to providing other routine services, such as out-patient, laboratory services, pharmacy services, emergency, delivery, family planning, and voluntary counseling and testing services etc. the feya general hospital accommodates a total of 150 beds with average patients/flow of 98 patients/day. figure. 1 geographical map of ethiopia and oromia region showing map of the study area (shashemene town) the study design it entailed a hospital-based cross-sectional study to evaluate the waste generation rate and its management system in the two hospitals of shashemene town. the study was conducted in three phases (3 weeks of study). during the first week, a trial collection exercise was conducted before initiation of the regular collection program. the purpose of the first phase (i.e., first week of the study) was to identify the main waste types and characteristics, learn the skills of determining the respective quantities generated from the different departments/case teams and plan the daily collection and segregation of waste during the study period. the center of the 2nd phase of study was the management of hospital solid waste while the nub of the 3rd phase was determining the amount of waste generated. in the latter two phases (phase 2 and 3), waste collection and measurement took place for seven consecutive working days. the proposed indicator for the evaluation of hospitals waste management was a daily generated amount of healthcare waste to one bed (general waste per bed per day and hazardous waste per bed per day). determination of sample size a stratified random sampling method was used to select the required categories of health east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 16 professionals. a random sample is one in which every element in the population has an equal and independent chance of being selected from the sample (crowther and lancaster, 2009). the total population size (n) of the two hospitals was 130, which comprise 75 nursing staffs, 33 medical staffs, and 22 other health and support staffs. this was pooled from government hospital (with 18 medical staff, 50 nursing staff and 12 other health staff) and private hospital (15 medical staff, 25 nursing staffs and 10 other health staff). the sample size (n) was determined using the slovin formula where n = number of samples, n = total population and e = error tolerance (level). accordingly, the sample size required for the study was calculated to be 98respondents from both hospitals. when fractionated based on proportional allocation, the sample size is constituted of 25medical staffs (15 from government, and 10 from private), 56 nursing staffs (35 from government, and 21 from private), and 17other health staffs (10 from government, and 7 from private). data collection the method adopted for this study follows the procedure used by longe and williams (2006). accordingly, data collection tools involved questionnaire survey, site visitation (personal observation) and key informant interview. the key informants were purposively selected and includes heath care directors, experts and policy developers in the zone. both the key informant interview and the direct observations were conducted by principal investigators while the questionnaires were administered subsequent to the translation (from english) to the local language of the study area (afan oromo). the site visit was conducted by using checklist to review the segregation, handling, collection and storage practices at the various case teams of the study hospitals. plastic polyethylene bags and labeled color coded waste containers were used for collection of solid waste from ward, laboratory and departments of the hospitals. the solid waste was manually separated (following appropriate safety precautions) into two categories such as hazardous and nonhazardous as designated in who guideline (who, 1999). electronic balance, calculator and recording forms were used for solid waste measurement and recording. waste generation per day was determined by taking the fraction of the total waste produced over the study duration by the length of the study period (7 days) in kg day–1. the solid waste generation can be computed by dividing the total weight of waste (in kg) generated per day with the number of beds in the hospital (i.e., the vacant beds were not considered) expressed as kg/bed/day or dividing the total weight of waste (in kg) generated per day with number of inpatients attended daily in the hospital expressed as kg/patient/day (kagonji and manyele, 2011). likewise, alagha et al. (2018) stated that a universal indicator of medical waste (mw) generation is the weight of healthcare waste generated per bed per day (kg bed–1 day–1) for a given medical facility. accordingly, waste generation per (occupied) bed per day was calculated as given below: east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 17 wbd = [mw weight (kg)]/[(day) × (bed)] where wbd, is defined as the total weight of mw (in kg) generated per occupied bed per day. data analysis the data was entered into spread sheet of microsoft excel and exported to statistical package for social sciences (spss version 20) for analysis. for testing the bi-variate association between hazardous waste generated, patient flow, and occupied beds in study hospitals, spearman’s rank correlation (rs) was computed following gerald et al. (2004). healthcare waste (hcw) generation rate and categories of hcw among the different case teams in each hospital were compared using kruskal-wallis-test as indicated in gerald et al. (2004). data from key informant interviews and direct observation were analyzed by theme and the content analysis was made manually, by sorting the organized information according to thematic similarities and differences. p-value and rs was reported to present the extent of strength in terms of significant variation and association between two variables, in that order. in all the analysis, level of significance was set at p< 0.05. results and discussion healthcare solid waste management practice healthcare solid waste segregation in general, there is poor segregation of hazardous solid wastes even though the hospitals employ separate receptacles/bins. besides, as reported by katusiime (2018), non-hazardous wastes (nhws)/general wastes (gws) were often mixed with infectious wastes in the government hospital (gh). notwithstanding this, both hospitals employed specific/separate bins for the collection of infectious wastes, and sharp wastes were collected in puncture proof safety boxes. conversely, the hospital solid waste segregation practiced in private hospital (ph) was relatively better than the same for the gh. in similar vein, lack of proper hcw segregation in ethiopia was reported by tesfahun (2015), hayleeyesus and cherinet (2016), meleko and adane (2018), and yazie et al. (2019). in urban referral hospital in uganda, katusiime (2018) also reported that though waste was generally discarded in large waste bins and sharps in separate sharps containers, the notion of waste segregation was non-existent. on the other hand, as with tesfahun (2015), the reuse and recycling practice of the nhws were almost absent in both hospitals; in the gh, however, it was observed that there was some reuse of drug containers (e.g., cans, plastic and bottles) without any precautions. similarly, meleko and adane (2018) found that there were no any observed activities performed by health professionals or other staff to reuse or recycle materials. in the ph, healthcare solid wastes were merely segregated into infectious, sharps and pathological wastes whereas in gh the segregation was almost absent except the segregation of sharp waste using the safety box. on the other hand, placentas and blood stained cotton pads were kept in separate containers in ph. in the gh, in contrast, anatomical wastes are collected with wound east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 18 dressings, placentas and blood/fluid-stained pads in a receptacle outside the wards (figure. 2d). on the other hand, the use of waste containers with a color code and labelling at the point of generation was implemented in both hospitals. however, it was observed in gh that some receptacles with different colorcodes were observed and, hence a color codelabel mismatch was practiced (e.g., blue and green plastic bins were employed for infectious wastes and non-infectious wastes, respectively) (figure. 3). yazie et al. (2019) in their review of studies conducted on ethiopian hospitals indicated that there was no use of proper color-coded bins for waste segregation. this may result in hazardous wastes not only being disposed inappropriately, but also with members of the community gaining access to such wastes. similar non-compliance had been reported in primary healthcare centers assessments conducted in several developing countries such as laos, turkey, mongolia, among others (yong et al., 2009; sanida et al., 2010). consequently, as to katusiime (2018), this will inevitably increase health risks to health workers, waste disposal workers, and the public. generation. figure 2. waste collection and storage systems near the beds (a and b), in corridors (c), outside wards (d) in the government hospital, shashemene, ethiopia figure 3. cases where there were color code–label mismatches in the government hospital on the other hand, only 25% of the respondents from gh acknowledged that the wastes were segregated at the point of generation while 50% of the study participants from ph expressed recognition of the practice of segregation at the place of generation east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 19 (table 1). waste is segregated depending on the quantity, composition, and the disposal method of the waste stream (shareefdeen, 2012). the present finding was similar with a finding obtained in addis ababa (ethiopia) where almost all of assessed hospitals reported that there was no segregation of wastes and, had no separate bins for the collection infectious waste (debere et al., 2013). as to who (2014), segregation of solid wastes should be performed by the producer of the waste as close as possible to its place of generation. figure 4. waste collection and storage systems near the beds (a and b), outside the bed rooms (i.e., in corridors) (c), outside the wards (d) in the private hospital, shashemene, ethiopia healthcare solid waste collection, interimstorage and transport the arrangements of hospital solid waste collections and storages adjacent to the bed, in the corridor, and outside the wards are presented in figures 2 and 4. in gh, solid waste generated was usually deposited into the small open plastic bins and open drug cartons close to the bedside, which ultimately produce unhygienic condition near the bed (figures 2a and b). conversely, in ph, the solid waste generated in similar location is collected in partially closed receptacles/bins placed away from each bed (figure 4a and b). all wards of the gh use substandard dustbins storages, such as trash bags, plastic buckets and drug cartons (that can be easily damaged) to store hcw temporarily in open for about 12–24 hours (figure 2). in government hospitals, tayework (2016) reported that all hospital solid wastes were temporarily stored in open and substandard dust bins for about unlimited time. the data presented in table 1 shows that 75% of the respondents from gh indicated that the wastes were collected once per day. conversely, in ph, colored plastic bins were placed in the designated place (figure 4a) in each room while leak-proof containers made from stainless steel were placed outside the rooms (figure 4d). besides, in ph, healthcare waste was collected on daily basis by cleaning personnel and transported to the on-site handling area. as to the information displayed in the table 1, 40% and 60% of the respondents from ph laid out that the wastes were collected once and twice a day, in that order. in all studied healthcare facilities, hayleeyesus and cherinet (2016) reported that hcw is collected on a daily basis by cleaning personnel and transported to an on-site handling area. on the other hand, in both hospitals, only pathological and sharp wastes were collected, stored and transported in closed plastic buckets/containers within an hour. on the contrary to other hazardous wastes (hws) like potentially infectious and east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 20 sharp wastes were collected in puncture-proof containers (safety boxes) in both hospitals (figures 2 and 3a). as to who (2014), collection times should be fixed and appropriate to the quantity of waste produced in each area of the healthcare facility and recommends that collection should be carried out daily for most wastes, with collection timed to match the pattern of waste generation during the day. table 1. participants’ response on the waste collection, treatment and disposal practices at the surveyed hospitals question response hospital government private do you segregate waste at the point of generation? yes no i don’t know 3(25%) 7(58.3%) 2(16.7%) 5(50%) 4(40%) 1(10%) do you use gloves, boots, masks & caps when handling hcw? yes no 3(25%) 9(75%) 4(40%) 6(60%) on-site handling (patient’s bed to storage place) once per day twice per day irregular 7(58.3%) 1(8.4%) 4(33.3%) 5(50%) 3(30%) 2(20%) on-site handling (storage place to final disposal) once per day twice per day irregular 9(75%) 1(8.3%) 2(16.7%) 4(40%) 6(60%) 0(0%) bags were filled with more than ¾ (75%) yes no i don’t know 7(58.3%) 3(25%) 2(16.7%) 6(60%) 4(40%) 0(0%) the filled bags were closed tightly before transferred yes no i don’t know 6(50%) 2(16.7%) 4(33.3%) 5(50%) 2(20%) 3(30%) the filled bags were replaced with empty one at the same time of discharge yes no 5(41.7%) 7(58.3%) 7(70%) 3(30%) vessel used for the transport of a sharp waste was perforated yes no 8(66.7%) 4(33.3%) 2(20%) 8(80%) waste treatment method used incineration open burning burial 9(75%) 2(16.7%) 1(8.3%) 6(60%) 2(20%) 2(20%) do you treat hazardous hcw differently from general waste? yes no i don’t know 5(41.7%) 3(25%) 4(33.3%) 7(70%) 2(20%) 1(10%) from ph and gh involved in the present study, only 40% and 25% of the respondents, respectively, indicated that waste bags and sharp containers were filled to ¾ full (table 1). waste bags and sharps containers should east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 21 be filled to no more than three quarters full and once this level is reached, they should be sealed ready for collection (who, 2014). on the other hand, 70% and 41.7% of the participants from ph and gh, respectively, made known that the filled bags were replaced with empty one during waste collection (table 1). replacement bags or containers should be obtainable at each waste-collection location so that full ones can immediately be replaced (who, 2014). as with tesfahun (2015), tayework (2016) and meleko and adane (2018), both hospitals lack of proper and purpose-built waste storage rooms; however, there was a temporary waste storage room for pharmaceutical wastes in the ph. conversely, similar to the findings reported by meleko and adane (2018), both hospitals employ interim waste storage (plastic bucket) outside the wards; wastes were stored for 24‒36 and 12‒24 hours in the gh (figure 2d) and ph (figure 4d) hospitals, respectively. debere et al. (2013) observed that hospital solid wastes were stored in temporary storage area from 2 weeks up to one month before final disposal. on the other hand, in both hospitals, the janitors handle the hws without wearing personal protective equipment (ppe) and empty (discard) the smaller containers into the larger ones which are placed in the corridors and outside the door. accordingly, 75% and 60% of the respondents from gh and ph, in that order, revealed that the waste handlers did not employ ppe while managing of the wastes. in a similar study by meleko and adane (2018), only about 24% of the waste collectors/waste handlers had worn glove and boots during waste collection and transportation of healthcare wastes. in their study on the east and west kumbo health districts of cameroon, dzekashu et al. (2017) found that the use of ppe like gloves (100%) were the most common practice by waste handlers, followed by aprons (85.2%) and boots (55.6%). in gh, hws and nhws were mixed outside each room (figure 2d), and transported to incineration area using wheeled trolleys/handcart (figure 5a), waste bags (carrying the same by their hands, on their shoulders, or using pushcarts) (figures 5a and b). although the transport of hcws in the ph was comparatively better and principally involved wheeled trolleys/carts (figure. 5c and d), the same appeared not to be appropriately sized according to the volumes of waste generated at a health-care facility. moreover, during the transport of the solid wastes from the interim storage receptacles to the treatment area within the hospital premises could entail the possibility of infectious waste droppings on the walkways (figure 5). awodele et al. (2016) indicated that wheel barrows and trolleys comprised the major means of evacuating the waste whereas dzekashu et al. (2017) observed that transportation of medical waste was virtually (96.7%) executed by lifting, and only 3.3% of the health facilities employed trolleys for transporting wastes.0.05). east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 22 figure 5. healthcare solid waste transport in the government (a, b) and private (c, d) hospitals healthcare solid waste treatment and disposal practice in both hospitals, waste storage and transporting plastic buckets were not treated with disinfectants as suggested by who (2014). besides, as with tesfahun (2015), none of the hospitals practiced pre-treatment of highly infectious waste. however, the laboratory department of the ph treated infectious waste (including cultures and stocks, sharps, materials contaminated with blood, etc.) by autoclave machine. conversely, 41.7% and 70% of the respondents from gh and ph, respectively, maintained the belief that hws should be treated differently from gws (table 1). the existing methods employed to treat solid wastes by both hospitals, in their order of importance, were incineration (brick-made to burn sharp wastes), open burning, and burial (table 1). as a rule, the choice of treatment system involves consideration of waste characteristics, technology capabilities and requirements, environmental and safety factors, and costs – many of which depend on local conditions (who, 2014). in gh, there was construction of new incinerator for treatment at the time of study because the former one became out of use due to unavailability of gas connection, old and filled with ash (figure 6a). consequently, the partially burned healthcare solid waste was further burnt and disposed of in an open pit within the gh (figure 6b and c). in the ph, conversely, the incinerator was not only properly functioning as depicted by incomplete burning of waste (figure 7a and b), but also was located close by the residential area of the medical staff within the hospital premises. consequently, apart from failure to significantly reduce the volume of treated waste, incinerators of both hospitals generated a plume of smoke to their immediate environments. the use of low combustion single-chamber incinerators for the treatment of healthcare waste was against the stockholm convection on persistent organic pollutants (pops) (unep, 2009) since such incinerators release air pollutants to the environment (diaz et al., 2005). on the other hand, both hospitals had an open hand dug pit in their backyard that was used for the open burning and direct dumping of gws. while the gh had an open placental pit for disposal of pathological and anatomical east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 23 waste generated from the delivery and operation rooms (figure. 6d), the ph employed one closed placental pit (figure. 7c) and two closed ash pits. as with the case reported by meleko and adane (2018), hcws in both hospitals were not disposed of in appropriate sealed and labeled containers. such malpractices were also reported in jos metropolis, nigeria (ndidi et al., 2009). generally, each component of hcw management practices in both surveyed hospitals did not conform to the ethiopian national healthcare waste management guideline. such poor hcw management were also reported in similar studies conducted in nigeria (di bella et al., 2012), south africa (nemathaga et al., 2008), and iran (de titto et al., 2012). figure 6. solid waste treatment methods: (a) incineration, (b and c) open burning at waste dump site and (d) anatomical, pathological and placental burial pits in the government hospital of shashemene town. figure 7. solid waste treatment methods: incineration (a and b), and (c) anatomical, pathological and placental pit employed in the private hospital waste generation and characterization the total weight of hcw generated in gh and ph in shashemene town were 316.5 kgweek–1 and 140 kg week–1, respectively. conversely, an average total of 45.2 ± 5.8kgday–1(0.20kg bed‒1day‒1) of hcw was generated from gh whereas only below half east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 24 as much (20 ± 2.4kg day–1 or 0.19kg bed‒1day‒1) of the same was produced from ph (tables 2, 3, and 4). although the above generation rate was somehow comparable to 0.164 kg bed‒1day‒1 reported by meleko and adane (2018), the same was lower than a result obtained in ethiopia (1.5kgbed‒1day‒1: tesfahun, 2015), bangladesh (1.24kgbed‒1day‒1: hassan et al., 2008), egypt (1.03kgbed‒1day‒1: shouman et al., 2013) and france (3.3kgbed‒1day‒1: windfeld and brooks, 2015). variations in waste generation hinges on the type or level of healthcare facility (who, 1999; bdour et al., 2007; haylamicheal et al., 2011; who, 2014), hospital specializations (who, 1999), location (rural or urban) (who, 2014), established waste management methods, proportion of reusable items employed in healthcare facilities (who, 1999; bdour et al., 2007; haylamicheal et al., 2011), level of activity (number of occupied beds, number of patients per day, and/or number of staff), type of department, temporal variations (e.g. weekday versus weekend, seasonal), and level of infrastructure development of the country (bdour et al., 2007; haylamicheal et al., 2011; who, 2014). table 2. distribution and healthcare solid waste generation rates by point source and type in government hospital of shashemene government hospital nonhazardous waste (kg week–1) hazardous waste (kg week–1) total hospital waste (kg week–1) percentage of total hospital waste (%) average daily hospital waste (kg day–1) iw phw sw* paw opd 30.3 5.9 14 0.6 7.0 57.8 18 8.3 surgical 27.9 4.7 3.9 1.5 38 12 5.4 pediatrics 20.4 7.3 3.5 4.7 8.1 44 14 6.3 obs/gyn. 16.5 9 9 5.2 10.2 49.9 16 7.1 medical 27.6 10.5 2.4 1.6 3.1 45.2 14 6.5 laboratory 15.9 5.5 8.9 2.7 9.1 42.1 13 6.0 emergency 30 4.2 3.2 2.1 39.5 13 5.7 total (kg week–1) 168 47.1 41.7 19.5 39.6 316.5 100 45.2 ± 5.8 mean ± sd (kg day–1) 24.1 ± 6.3 6.7 ± 2.3 6.0 ± 4.8 2.8 ± 1.7 5.7 ± 3.9 45.2 ± 5.8 % wt. by type 53.3 14.8 13.2 6.2 12.5 100 iw = infectious waste; phw: pharmaceutical waste; sw: sharp waste; paw: pathological waste *includes needles, blades, lancet needles, syringes, and scalpel blades of the total waste generated in gh, 53.3% (24.1 ± 6.3 kg day–1 or 0.1 kg bed‒1day‒1) was gw while 46.7% (21.1 ±3.2 kg day–1 or 0.091kg bed‒1day‒1) was hw (tables 2 and 4). equally, of the total waste generated in ph, 57.1% (11.4 ± 2 kg day–1 or 0.11 kg bed‒1day‒1) was gw whereas 42.9% (8.6 ± 1.3 kg day–1 or 0.079 kg bed‒1day‒1) was hw (tables 3 and 4). a little over half of the total hcw generated from the study hospitals (gh: east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 25 53.3%; ph: 57.1%) constituted gw. meleko and adane (2018) reported that 0.091 kg /bed/ day (55.5%) was gw and the remaining 0.073 kg/bed/day (44.5%) was hw. likewise, in similar studies conducted in ethiopia, azage and kumie (2010), debere et al. (2013), and hayleeyesus and cherinete (2016) the gw accounted for the 52, 58.69, and 65.1% of the total hcw. moreover, the result of the present study is comparable with a results obtained from healthcare facilities in ethiopia where 48% (azage and kumie, 2010), 41.31% (debere et al., 2013), and 42.1% (meleko and adane, 2018) of hcw were hw. conversely, the present finding was much bigger than a result identified in sudan where only 20% of the total hcw generated was hw (ahmed et al., 2014). on the other hand, between 75% and 90%of the waste produced by health-care providers are actually nhws or gws, and the remaining 10‒25% is hws in nature (who, 2014). it is apparent that the proportions accounted by hws from the present study were higher than the same reported by the who (2014). yazie et al. (2019) pointed out that the fractions of hw generated from healthcare facilities were intolerably high with a range stretching from 21‒70% of the total solid waste. as indicated by hayleeyesus and cherinete (2016), the higher proportion of hws in the present study (as well as in most healthcare facilities in ethiopia) could be ascribed to the lack of segregation of waste at the point of generation. in a study done on private and government hospitals, debere et al. (2013) found that the hw and non-hws were mixed in the hospital’s temporary storage areas. table 3. distribution and healthcare solid waste generation rates by point source and type in private hospital of shashemene private hospital nonhazardous waste (kg week–1) hazardous waste (kg week–1) total hospital waste (kg week–1) percentage of total hospital waste (%) average daily hospital waste (kg day–1) iw phw sw * paw opd 11.5 0.5 4.1 1.5 3.0 20.6 14 2.9 surgical 12.1 2.3 2.5 2.5 2.2 21.6 15 3.1 pediatrics 13.3 3.1 2.4 0.8 3.2 22.8 17 3.3 obstetrics/gyn. 11.9 2.0 0.7 1.6 4.1 20.3 15 2.9 medical 8.2 1.9 4.2 2.2 1.5 18 13 2.6 laboratory 9.4 4.3 2.0 15.7 11 2.2 emergency 13.6 1.2 4.6 0.4 1.2 21 15 3.0 total (kg week–1) 80 15.3 18.5 11 15.2 140 100 20 ± 2.4 mean ± sd (kg day–1) 11.4 ± 2.0 2.2 ± 1.2 2.6 ± 1.8 1.6 ± 0.8 2.2 ± 1.4 20 ± 2.4 % wt. by type 57.1 10.9 13.2 7.9 10.9 100 iw = infectious waste; phw: pharmaceutical waste; sw: sharp waste; paw: pathological waste *includes needles, blades, lancet needles, syringes, and scalpel blades. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 26 the types of hazardous wastes generated from the study hospitals were infectious, pharmaceutical, pathological, and sharps. in both hospitals, the infectious [gh: 14.8%; ph: 10.9%] and pharmaceutical [gh: 13.2%; ph: 13.2%] wastes dominate the hws category while sharp wastes [gh: 6.2%; ph: 7.9%] contribute for the lowest fractions to the total as well as to the selfsame category in either hospital (tables 2 and 3). in a similar vein, hayleeyesus and cherinete (2016) found that infectious waste (21.1% of the total hcw) dominated the hw fraction while the sharp waste contributed the least (1.5%) to the total solid waste from the healthcare facilities. table 4. average daily healthcare solid waste generation by types of wastes in shashemene hospitals types of waste type of hospital government private kg day–1 kg bed–1 day–1 kg day–1 kg bed–1 day–1 general waste 24.1 0.1 11.4 0.11 infectious waste 6.7 0.03 2.2 0.02 pharmaceuticals 5.9 0.025 2.6 0.024 sharps 2.8 0.012 1.6 0.015 pathological wastes 5.7 0.024 2.2 0.02 total hcsw 45.2 0.20 20 0.19 hcsw stands for healthcare solid waste in the gh (table 2) the highest percentage of the total hcw was generated from opd (18%) followed by obstetrics/gynecology (16%) while the lowest proportion of total waste was generated from surgical ward (12%). on the other hand, the pediatric ward (17%) followed by obstetrics/gynecology, emergency, and surgical wards (15% each) contributed for the highest fractions of total waste generated from ph whereas the waste proceeding from the laboratory (11%) was the lowest proportion of the total hcw (table 3). meleko and adane (2018) reported that the largest portions of total waste were contributed by gynecological ward followed by medical ward while the lowest proportion was generated in office. as to the data presented in table 5, there were significant differences in the different wards of the government hospital with respect to general waste (χ2 = 31; p <0.001), hazardous waste (χ2 = 25; p <0.001), and total healthcare waste (χ2 = 46; p <0.01). likewise, significant variations were observed in the private hospital wards regarding the general waste (χ2= 13; p <0.01), hazardous waste (χ2 = 10; p <0.01), and total healthcare waste (χ2 = 22; p <0.01). similarly, meleko and adane (2018) reported that there were significant variations among the different wards in relation to general waste (χ2=41.815;p< 0.01), hazardous waste (χ2=44.324;p<0.01), and total healthcare waste (χ2 = 44.604;p< 0.01). east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 27 table 5. comparison of mean generation rate of healthcare solid waste and categories of hcsw by departments within the government and private hospitals using kruskal wallis h test wards type of hospital government private gw hw thcw gw hw thcw opd 30.3 27.5 57.8 11.5 9.1 20.6 surgical 27.9 10.1 38 12.1 9.5 21.6 pediatrics 20.4 23.6 44 13.3 9.5 22.8 obs/gyn. 16.5 33.4 49.9 11.9 8.4 20.3 medical 27.6 17.6 45.2 8.2 9.8 18 laboratory 15.9 26.2 42.1 9.4 6.3 15.7 emergency 30 9.5 39.5 13.6 7.4 21 chi-square 31 25 46 13 10 22 p-value 0.0001 0.0001 0.001 0.001 0.001 0.001 gw: general waste; hcw: healthcare waste; hw: hazardous waste; obs/gyn: obstetrics/gynecology; opd: outpatient department according to table 6, there were significant differences between the mean total hcw (χ2 = 9.016;p< 0.01), general waste (χ2 = 9.8;p< 0.01) and the hazardous waste (χ2 = 5.011;p< 0.05) of the study hospitals. similar to the findings of the present study, debere et al. (2013) reported that there was statistically significant difference for total amount of hcw (χ2 = 30.65;p< 0.001),hw (χ2 = 20.431;p < 0.01) and nhw (χ2 = 29.011;p< 0.001) among the surveyed hospitals. table 6. comparison of healthcare waste generation rates and categories of hcw using kruskal-wallis test among the surveyed hospitals type of hospital mean rank total hcw* gw** hw*** government 10.86 11.00 10.00 private 4.14 4.00 5.00 chi-square 9.016 9.800 5.011 pvalue 0.003 0.002 0.025 * healthcare waste, ** general waste, *** hazardous waste the spearman’s rank correlation coefficient (rs) (table 7) showed that there was a positive linear relationship between number of patients and quantities of hazardous waste generation rates in both ph (r = 0.954, p< 0.05) and gh (r = 0.847, p< 0.01). similarly, there was positive correlation coefficients among hw generation rates and occupied beds in both ph (r = 0.964, p< 0.05) and gh (r = 0.821, p< 0.001) (table 7). moreover, positive associations were observed between patient flow and occupied beds in ph (r = 0.991, p< 0.01) and gh (r = 0.955, p< 0.05). in their study on hcws, tadesse and kumie (2014) found that there was a positive linear relationship between number of patients and east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 28 the hcws generated in all government facilities studied. conversely, issam et al. (2009), haylamicheal et al. (2011), and komilis et al. (2011) reported that there was a positive correlation between the total hcw generation rates and the number of beds. table 7. spearman’s correlation matrix (rs) between hazardous wastes (hw) generated, patient flow and occupied beds in private and government hospitals government hospital hw patient flow occupied beds spearman’s rho hw 1.00 0.954⁎⁎ 0.964⁎⁎⁎ patient flow 1.00 0.955⁎⁎ occupied beds 1.00 private hospital hw patient flow occupied beds spearman’s rho hw 1.00 0.847⁎ 0.821⁎ patient flow 1.00 0.991⁎⁎ occupied beds 1.00 ⁎, ⁎⁎, and ⁎⁎⁎ represent p < 0.05, p < 0.01, and p < 0.001, in that order conclusion although the hcw generations rates were relatively low, the standard hcw segregation was lacking in both hospitals. consequently, except the sharp materials, all other hcws were mixed with the gws (mainly in gh), and hence, the proportion of hws generated in the study hospitals surpassed the corresponding threshold measure indicated by the who. besides, the waste collectors handle the hcws without employing ppe, exposing themselves to potential health risk. both hospitals principally treated hcw using low combustion single-chamber incinerators which could potentially contribute to the release of huge amounts of air pollutants to the environment. as the hcw management in both hospitals was poor, sufficient resource allocation, periodic training, and strict supervision and proper implementation of hcw management is pivotal. additionally, heath care facilities in oromia region, should acquaint hcw management guideline for standardized waste categorization and safer handling. besides, the key stakeholders of the region involving heath care directors, experts and policy developers should join hands in structuring the hcw management system in a way that appraises human and environmental health. for this, further researches need to be conducted in health care facilities of the region and the wider nation with consideration of human health risk assessment. ethical consideration ethical clearance was obtained from zonal health office whereas an approval to conduct the study was secured from the managers/directors of the respective hospitals. the experimental procedures were explained to the individual participants and thereafter their consent to participate in the study was obtained. the participants were free either to participate or not. besides, the right east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 13-30 29 of respondents to interrupt or withdraw the interview when they deem it necessary was duly respected. data collectors were trained touse protective materials when handling healthcare wastes. privacy and confidentiality were assured by way of employing anonymity. conflicts of interest the authors declare that there are no conflicts of interest regarding the publication of this paper. acknowledgements many individuals and institutions have helped us while conducting the present study. we are highly appreciative of the cooperation of the study hospitals (the administration, healthcare workers and waste handlers). we are deeply indebted to adanech bekele guta for her support and suggestions to execute the research work. we are grateful to ato melesa bekele tola for his assistance with equipment calibration, invaluable comments and information relevant to execute this work. references abd el-salam m. 2010. hospital waste management in el-beheira government, egypt. j. environ. manage. 91: 618–629. ahmed n.o., gasmelseed g.a. and musa a.e. 2014. assessment of medical solid waste management in khartoum state hospitals. jpn. j. ind. appl. indu. sci. math. 2014, 2 (4): 201–205. alagha o., alomari a., and jarrah n. 2018. medical waste management and production rate in the eastern province of the kingdom of saudi arabia. euro-mediterr. j. environ. integration 3:35. https://doi.org/10.1007/s41207-018-0078-5 al-khatib i.a. and sato c. 2009. solid health care waste management status at healthcare centers in the west bank–palestinian territory. waste manage. 29:2398–2403. awodele o., adewoye a.a. and oparah a.c. 2016. assessment of medical waste management in seven hospitals in lagos, nigeria. bmc public health 16:269. azage m. and kumie a. 2010. healthcare waste generation and its management system: the case of health centers in west gojjam zone, amhara region, ethiopia. ethiop. j. health dev. 24(2):119‒126. bdour a., altrabsheh b., hadadin n. and al-shareif m. 2007. assessment of medical wastes management practice: a case study of the northern part of jordan. waste manag. 27(6):746‒759. coker a., sangodoyin a., sridhar m., booth c., olomolaiye p. and hammond f. 2009. medical waste management in ibadan, nigeria: obstacles and prospects. waste manage. 29: 804–811. crowther d. and lancaster g. 2009.research methods: a concise introduction to research in management and business consultancy, routledge. de titto e., savino a.a. and townend w.k. 2012. healthcare waste management, the current issues in developing countries. waste manage. res. 30(6): 559–561. debere m.k., gelaye k.a., alamdo a.g. and trifa z.m. 2013. assessment of the healthcare waste generation rates and its management system in hospitals of addis ababa, ethiopia. bmc public health 13:28. di bella v., ali m. and vaccari m. 2012. constraints to healthcare waste treatment in low-income countries: a case study from somaliland. waste manage. res.30(6): 572‒575. diaz l.f., savage g.m. and eggerth l. 2005. alternatives for the treatment and disposal of healthcare wastes in developing countries. waste manag. 25 (6):626-37. dzekashu l.g., akoachere j.f. and mbacham w.f. 2017. medical waste management and disposal practices of health facilities in kumbo east and kumbo west health districts. int. j. med. med. sci. 9(1): 1‒11. eepa, 2006. federal democratic republic of ethiopia environmental protection authority national implementation plan for the stockholm convention. ethiopia environmental protection authority (eepa). berhan & selam printing, addis ababa, ethiopia. farzadkia m., moradi a., mohammadi m.s. and jorfi s. 2009. hospital waste management status in iran: a case study in the teaching hospitals of iran university of medical sciences. waste manage. res. 27(4):384‒389. gerald v.b., lioyd d., patrick j. and thomas l. 2004. biostatistics: a methodology for the health east afr. j. biophys. comput. sci. 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(2023), vol. 4, issue. 2, 1-12 *corresponding author: email: msulayeman@gmail.com https://dx.doi.org/10.4314/eajbcs.v4i2.1s sero-epidemiology of foot and mouth disease and farmers perception on vaccinating cattle against the disease in sidama region, southern ethiopia mishamo sulayeman*1, tamirat demissie1, ayelech muluneh2, gizachew hailegebreal1, sultan abda1 1faculty of veterinary medicine, hawassa university, p.o. box 05, hawassa, ethiopia. 2national animal health diagnostics and investigation center, p.o.box 04, sebeta, ethiopia. keywords: cattle; ethiopia; farmers perception; fmd; sero-prevalence; vaccination abstract ft and mouth disease (fmd) is a severe, highly cntagious viral disease of livestck that has a significant economic impact. a cross-sectional study was conducted from september 2019 to june2020 in three selected districts of sidama region, southern ethiopia with the objectives of determining the sero-prevalence of cattle against foot and mouth disease virus (fmdv), identifying potential risk factors and assessing farmers’ perception on vaccination against fmd. purposive and systematic random sampling techniques were employed to select the districts and study animals, respectively. a total of 510 cattle were tested for fmdv antibodies using 3abc-elisa. the overall cattle and herd level sero-prevalence were 15.5% and 24.7%, respectively. among the considered risk factrs, age of the animal, herd size and season were significantly associated with the sero-positivity of fmdv (p<0.05). out of 120 farmers interviewed 84.2% had never vaccinated their cattle against fmdv. inaccessibility (83.7%) and unaffordable cost (72.1%) of the vaccine were mentioned as leading causes for the low vaccination practice in the current study areas. majority of the respondents (68.3%) don’t perceive vaccinating cattle against fmdv as one of the preventive measures. in districts with lower perception of farmers on vaccinating their cattle against fmdv, higher sero-prevalence of the disease were recorded. the present serological and questionnaire survey indicated that the presence of fmd sero-positive animals in the current study areas. therefore, an integrated strategy for disease control has to be designed and implemented which could include enhancing farmers’ perception about use of vaccination in preventing fmd and government provision of vaccines at affordable cost to the farmers. . introduction ethiopia is one of the countries that possess a huge number of livestock populations in the africa continent estimated to be 56.5 million cattle, 30.7 million sheep and 30.2 million goats were found in the country (csa, 2017). the livestock sector contributes about 40% of the agricultural gross domestic product (gdp) and nearly 20% of total gdp, and 20% of national east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article mailto:msulayeman@gmail.com https://dx.doi.org/10.4314/eajbcs.v4i2.1s east afr. j.biophys.comput. sci. (2023), vol. 4, no. 2, 1-12 2 foreign exchange earnings in 2017 (world bank, 2017).within the cattle population, fmd occurs endemically resulting in several outbreaks every year (ayelet et al., 2012). the causative agent, fmd virus (fmdv), has seven recognized serotypes (o, a, c, sat 1, sat 2, sat 3 and asia 1), with discrete immunologic, antigenic and genetic properties. they also differ in distribution across the globe (fao, 2007). five of the seven serotypes of fmd (o, a, c, sat 2, sat 1) were identified in ethiopia (rufael et al., 2008; ayelet et al., 2009; negusssie et al., 2010). serotype c was not identified after 1983; however, a serotype cspecific antibody in cattle was reported (rufael et al., 2008). morbidity has been reported to reach as high as 100% in susceptible animal populations but it is rarely fatal except in young animals (kahn and scottline, 2005). infected animals show a spectrum of responses to fmd ranging from unapparent infection to severe disease and death (oie, 2008). foot and mouth disease is endemic with high prevalence in africa, the middle east, and asia and is also present in parts of south america (rweyemamu and astudillo, 2002). the disease is endemic in ethiopia and remains largely uncontrolled due to the absence of prophylactic vaccination except for a few dairy herds containing imported breeds (sahle, 2004;megersa et al., 2009). serological surveys reported a sero-prevalence that ranges from 5% to 72.1% at the animal level in different parts of the country (bayissa et al., 2011, sulayeman et al., 2018; shazali et al., 2021). in terms of livestock exports from africa, fmd is often perceived as a major hindrance to international trade (thomson et al., 2004). in part, this perception is based on the assumption that disease freedom is required before export is possible, and has resulted in costly and an elaborated fmd control measures such as disease-free zones in southern africa and elsewhere (bruckner, 2004). commodity based approaches can provide an acceptable level of risk for exported livestock or livestock products according to international standards(thomson et al., 2004), but in the case of fmd, they still require an understanding of fmd status in cattle entering the market chain. recommended control measures for fmd include animal movement restrictions, a vaccination programme, animal quarantine, environmental sanitary controls, outbreak investigation, serological surveillance and slaughtering of sick animals (chaosuancharoen, 2012). however, it is a global problem since the result of the increasing movement of human and livestock and livestock products (perry, 2007). this is mainly due to lack of vaccination, free livestock movement among different regions in the countries and across international borders, the existence of multiple fmd virus serotypes, and involvement of wildlife (sahle, 2004; rufael et al., 2008). studies undertaken in ethiopia revealed that the disease is still endemic and occurs in different parts of the country (sulayeman et al., 2018; shazali et al., 2021). there is neither a nationwide control strategy nor a legislation for making fmd notifiable to the veterinary authorities or for animal movement restrictions to be imposed. therefore, livestock is at risk from endemic strains as well as from antigenic variants prevailing in neighboring countries (sahle, 2004). there is a difference in the epidemiology and economic impacts of fmd in the livestock east afr. j.biophys.comput. sci. (2023), vol. 4, no. 2, 1-12 3 production systems (jemberu et al., 2014) in different parts of the country. unidentified farmers’ perceptions about risk of the disease, lack of pragmatic vaccination schemes and presence of unrestricted animal movement regardless of certification are the major reasons that could intensify the distribution of fmd alongside the cattle market chain. despite this fact, there is no published information regarding the status of fmd and farmers’ perceptions and practices on vaccinating their cattle against the disease in sidama region. therefore, this study was aimed to generate current information on the seroprevalence status of fmd and predisposing risk factors and assesses farmers’ perception on vaccination against fmdv in selected districts of sidama region, southern ethiopia. materials and methods description of the study area the study was carried out in three purposively selected districts of sidama region, namely hawassa zuria, boricha and wondo genet. sidama region is located northeast of lake abaya at an altitude of l500 to 2500 m.a.s.l. the region has gegraphic coordinates of latitude, north,5′ 45″to 6′ 45″ and lngitude, east, 38′ to 39′. mean annual rainfall of this area varies between 1200 mm and 1599 mm, with 15°c19.9°c average annual temperature (csa, 2015) (figure 1). . figure 1: map showing the study areas east afr. j.biophys.comput. sci. (2023), vol. 4, no. 2, 1-12 4 study design and sampling strategy a cross-sectional study design was implemented for sero-prevalence study of antibodies against fmdv in the study areas. hawassa zuria, boricha and wondo genet districts were selected purposively based on their transport accessibility, gegraphical location and presence of large cattle population. from each district 30% of kebeles (the smallest administrative units in ethiopia) were selected using simple random sampling. from each kebeles, 20% of privately owned herds were randomly selected. from each herd, the study animals (cattle) were then selected using simple random sampling method to achieve the required sample size. the alleged potential risk factors for the occurrence of the disease such as age, breed, sex, districts, herd size and composition, season, vaccination history and management were also recorded. sampled animals were categorized based on their breed (local and cross), sex (female and male), herd composition (cattle only and cattle mixed with small ruminants), vaccination history (previously vaccinated and non-vaccinated) and management types (intensive and semiintensive). ages (young, adult and old) were categorized based on their dental eruption status (berecha et al., 2011) and herd sizes where also classified as large farms size, with more than 50 animals, medium (20 to 50 animals) and small (< 20 animals) (edao et al., 2018). study animal population local and cross breeds of cattle kept under intensive and semi-intensive system were included. according to pace and wakeman (2003), the age groups of cattle were categorized as (≤3.5years) young, (3.5years‐5.5years) adult and (> 5.5years) old. sample size determination the sample size required for the study was calculated based on the following formula (thrusfield, 2005). n = z2*pexp (1pexp) d2 where, n= required sample size, z= statistic for level of confidence = 1.96, pexp = expected prevalence, 95% confidence level and d2 = absolute desired precision of 0.05. accordingly, based on the above formula and 9.5% expected prevalence (megersa et al., 2009), the sample size computed for animal level prevalence was 132. to increase the precision, calculated sample size was made four fold to 528, but due to shortage of sample collection materials only 510 cattle were considered. this number was allocated proportionally to the respective districts based on the total cattle population in each districts. serum sample collection from each cattle, about l0 ml of blood sample was collected from the jugular vein and kept overnight on a table at room temperature. then serum was aspirated with pasture pipette and transferred into cryovial and transported to hawassa university veterinary microbiology laboratory for storage at −20 °c. all the sera were transported with an ice box containing ice packs to the national animal health diagnostic and investigation center (nahdic) for serological test. https://www.ncbi.nlm.nih.gov/pmc/articles/pmc8464255/#vms3574-bib-0046 east afr. j.biophys.comput. sci. (2023), vol. 4, no. 2, 1-12 5 serological diagnostic tests sera collected from bovine species was tested by fmdv 3abc-ab elisa (id screen®) for the detection of antibody to poly protein called 3abc which is a useful indicator of fmd virus infection regardless of the serotype involved (haas, 1997; mackay et al., 1998). antibody to 3abc (nonstructural protein) is found only in virus infected cattles but not in vaccinated animals (de diego et al., 1997). briefly, the test was carried out stepwise as per the manufacturer’s manual. first, all reagents were kept at room temperature and homogenized by vortex. the test was carried out in 96 well micro plates. then 50μl of dilution buffer18 were added in to each well, 30μl of positive control were added in to wells a1 and b1, and the same volume of negative control were also added to wells c1 and d1, the rest wells were filled by 30μl of test sera. then incubated at 37oc for 2 hours, after incubation the wells were emptied with washing 5 times with 300μl of wash solution along with paying great attention to avoid drying of wells between washing. after washing l00μl of the conjugate lx were added in to each wells and incubated for 30 min at 21oc. the wells were then emptied and washed 5 times with 300μl of wash solution, then l00μl of the substrate solution was added in to each wells and incubated at 2loc for l5 minutes in the dark. after adding a 100μl of stop solution to each well, the optical density (od) reading was noted using a photometer at wavelength of 450 nm within 2 hours after the addition of the stop solution. questionnaire survey data concerning farmers’ perception towards vaccinating their cattle was collected by using a semi-structured pre-tested questionnaire. it was administered by interviewing individuals selected by systematic random sampling. before the interview, the objective of the survey was properly explained and verbal consent was obtained from the respondents. the interviews were conducted in local languages (sidaamu afoo or amharic). a total of 120 farmers, 40 farmers from each three districts were interviewed for the questionnaire survey. data management and statistical analysis data generated from the laboratory investigations and survey was recorded and coded using a microsoft excel spread sheet (microsoft corporation) and analyzed using stata version 13.0 for windows (stata corp. college station, tx, usa). the association between dependent and independent variables was analyzed at individual cattle level by using univariable and multivariable lgistic regression. multivariable logistic model was used for variables with a p-value ≤ 0.05 on univariable analysis model. further selection of variables in the final model was based on stepwise backward elimination procedure. accordingly, odds ratio (or) was used to assess the strength of association between the putative risk factors and sero-positivity of the disease. results fmd sero-prevalence and risk factors based on the total 510 sampled cattle, overall sero-prevalence of fmd was 15.5% and 24.7% at the individual animals and herd levels, respectively. comparatively higher seroprevalence (32.4%) was recorded in hawassa east afr. j.biophys.comput. sci. (2023), vol. 4, no. 2, 1-12 6 zuria district (p=0.02; or=2.67%; 95%ci=1.145.33) (table 1). table 1: individual cattle level and herd level sero-prevalence of fmd districts farmers associations individual cattle herds tested positive (%) tested positive (%) hawassazuria labu-koromo 68 9(13.2) 27 8(29.6) udo-wotate 65 16(24.6) 22 7(31.8) galo-argisa 64 12(18.7) 22 8(36.4) sub total 197 37(18.8) 71 23(32.4) boricha konser-fulasa 50 16(32) 31 11(35.5) fulasa-aldada 48 5(10.4) 24 5(20.8) hanja-chefa 52 7(13.5) 36 7(19.4) aldada-dela 58 5(8.6) 27 3(11.1) sub total 208 33(15.8) 118 26(22) wondo genet watara-qachama 56 5(8.9) 13 2(15.4) abayye 49 4(8.2) 20 4(20) sub total 105 9(8.6) 33 6(18.2) total 510 79(15.5) 222 55(24.7) risk factors breed of the cattle, sex, age, districts, herd composition and size, season, vaccination history and management types were the major exposure or predictor variables considered to predict the response of the outcome variable. table 2:lgistic regression analysis of fmd and its putative risk factors for sero-positivity of cattle. risk factors category no examined prevalence univariable multivariable no (%) positive or 95% ci pvalue or 95% ci pvalue districts wondo genet 105 9(8.6) ref. hawassa zuria 197 37(18.8) 2.67 1.14 – 5.33 0.02 0.63 0.37 – 5.23 0.63 boricha 208 33(15.8) 2.01 0.92 – 4.37 0.04 1.38 0.16 – 2.48 0.51 age young 58 3(5.2) ref. adult 67 5(7.5) 1.47 0.33 – 6.47 0.03 1.38 0.31 – 6.23 0.67 old 385 71(18.4) 4.14 1.26 – 13.6 0.02 3.60 1.04 – 12. 47 0.04 herd size small 262 31(11.8) ref. medium 229 46(20.1) 1.87 0.14 – 3.07 0.01 2.18 1.27 – 3.76 0.005 large 19 2(10.5) 0.87 0.19 – 3.97 0.46 1.03 0.21 – 5.03 0.97 managt. type intensive 78 6(7.7) ref. semiintensive 432 73(16.9) 2.44 1.02 – 5.82 0.04 2.65 0.34 – 20.97 0.35 season wet 38 14(36.8) ref. dry 472 65(13.7) 0.27 0.13 – 0.56 0.000 0.18 0.07 – 0.42 0.000 or= odds ratio; ci= confidence interval most of the documented variables revealed a high degree of association with fmdv infection or sero-positivity. the final multivariable lgistic regression model (table 2) revealed that age, herd size and season were significantly associated with the sero-prevalence of the disease (p<0.05). old cattle were 3.6 times at a higher risk of fmd than young cattle. east afr. j.biophys.comput. sci. (2023), vol. 4, no. 2, 1-12 7 farmers’ perception and practices related to fmd out of 120 respondents 64(53.3%) and 56 (46.7%) of them responded that their production is dairy cattle and mixed production type (table 3). bovine pasteurellosis, blackleg, lumpy skin disease, anthrax and fmd were listed in order of vaccination practice by the respondents (figure 2). figure 2: list of diseases and farmers practice to vaccinate their cattle against different animal disease. among the major cause for low vaccination practices against fmd in the study area, inaccessibility and unaffordable cost of the vaccine were mentioned by 83.7% (36/43) and 72.1% of the respondents, respectively. moreover, 68.3% (82/120) of the farmers interviewed don’t perceive vaccination as a preventive measure for the disease (table 4). table 4: farmer’s perception on vaccinating their cattle variables response frequency (%) dairy cattle production type yes 64(53.3) mixed production type yes 56(46.7) vaccinated their cattle against disease yes 120(100) perceive as vaccination is better than treatment yes 104(86.7) perceive vaccination as preventive measure against fmd yes 38 (31.7) vaccinated their cattle against fmd yes 19(15.8) fmd is a common disease yes 77(64.2) pervious occurrence of fmd in the farm yes 66(55%) information about fmd yes 108(90) information about fmd vaccination yes 43(35.8) 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00% bovine pasteurellosis black leg disease lumpy skin disease anthrax disease fmd 94.20% 90.00% 84% 60.80% 15.80% v ac ci n at in g a n im al s ag ai n st t h e d is ea se s east afr. j.biophys.comput. sci. (2023), vol. 4, no. 2, 1-12 8 sero-prevalence study of fmd overall sero-prevalence of fmd recorded in this study (15.5%)was in agreement with the previous findings of15.4% (mohamoud et al., 2011) and 14.05% (zerabruk et al., 2014)from jijiga zone and tigray respectively. in contrast, it is higher than previous reports made from different parts of ethiopia which range from 4.8% 12.08% (negussie et al., 2011; abunna et al., 2013; beyene et al., 2015; gelana et al., 2016; belina et al., 2016). compared to the present finding relatively higher sero-prevalence in bovine was reported as, 24.22%, 38.9% and 21.4% from central ethiopia (sulayeman et al., 2018), borena (melkamsew, 2018) and west ethiopia (desissa et al., 2014) respectively. similarly, higher sero-prevalence of the disease was also reported from the neighboring countries of africa, 52.5% in kenya (kibore et al., 2013), 61% in uganda (miaron et al., 2004) and 72.62% in nigeria (lazarus et al., 2012). these differences in the prevalence of the disease among the studies could be partly explained by the variation in agro-ecology; epidemiology of the disease and variations in the production or herding systems, vaccination coverage against fmd vaccine, immune status, interaction with cattle with other animals like small ruminants and management type of different study areas. cattle managed semi-intensively were shown higher sero-prevalence than those kept under intensive management. similarly, higher seroprevalence was previously recorded in cattle kept under semi-intensive managements (bedru, 2006). free movement of animals for watering point and grazing areas, and relatively larger herd holding capacity were the possible causes for the disease prevalence difference in different management system. this is supported by the work of previous studies report that the movement of animals in search of feeds from one area to another and interaction of small ruminants is a significant risk factor for the occurrence of fmd (gelaye et al., 2005;fevre et al., 2006; habiela et al., 2010). in the current study, sero-prevalence of fmd was significantly higher in old animals than in young groups. similar findings were also previously reported from central ethiopia (sulayeman et al., 2018) and awbere and babille districts of jijiga zone (mohamoud et al., 2011). aged caatle are more probably to have been exposed to fmdv during their lifetime and have developed immunity to the virus. additionally, old animals are driven freely in grazing and watering points where infection could increase by contact (jenbere et al., 2011). higher sero-prevalence was recorded during the dry seasons, which might be associated with herd movement to grazing area after crops were collected. this finding is supported by previous study as dry season increase the risk of fmd occurrence (sarker et al., 2011)and also described as fmd is a seasonal disease mostly seen during the dry season (jibat et al., 2013). because during the dry season, cattle may experience physiological stress due to the factors such as high temperatures, low humidity, and limited availability of fresh forage and water. this can deteriorate their immune response, making them more susceptible to fmd infection and increasing the sero-prevalence. nearly 87% of the respondents’ perceived vaccination is better than treatment, but only east afr. j.biophys.comput. sci. (2023), vol. 4, no. 2, 1-12 9 15.8% of them had vaccinated animals against the disease. similarly megersa et al (2009) reported that vaccine as prophylactic measures against fmd was accepted by most farmers, but very few of them regularly vaccinate their animals. on other hand, some farmers did not consider vaccination of fmd as significant prevention methods due to self-limiting disease and low mortality among affected animals. in a district, wondo genet, where farmers perceive and practice vaccine as a preventive measure, lower fmd sero-prevalence was recorded than the other districts. the study further revealed that 90% of respondents had information about fmd in the selected districts. similarly 92.5% awareness level was also previously reported from bale zone (misgana et al., 2013). from the respondents only15.8% vaccinate their cattle against fmd. lower vaccination practice against fmd was also reported from nigeria (olabode et al., 2014). however, comparable higher vaccination practices against the disease were reported from tanzania (miaron et al., 2004, moenga et al., 2013). inaccessibility and unaffordable cost of the vaccine were mentioned as a leading cause for the low vaccination practice in the current study areas. moenga et al. (2013) and soko et al. (2018) were also stated that aforementioned causes were the major reason for lower vaccination practices of the farmers. most of the respondents from the selected districts had experienced fmd outbreak in their farm at least once before the interview. in line with this investigation previous work reported that fmd is endemic, widely distributed and frequently noted in different farming systems and agro-ecological zones of the country (asfaw and sintaro, 2000; sahle, 2004; leforban, 2005). despite this fact 82(68.3%) of the farmers interviewed don’t perceive vaccination as preventive measure for the disease. in line with this finding most livestock owners don’t perceive vaccinating animals against fmdas one of the important preventive measures (moenga et al., 2013; soko et al., 2018). conclusions & recommendations the present serological study indicates that the presence of fmd sero-positive animals in the current study areas. semi-structured questionnaire based surveys indicated that farmers’ awareness about fmd vaccine is very low. even some farmers’ having awareness on fmd vaccine, their perception on vaccinating cattle against fmd is significantly low due to inaccessibility and unaffordability of the vaccine. the current research work explored the complex epidemiological situation of fmd and farmer’s perception on vaccine against the disease; thus needs more detailed investigation for vaccinebased control methods and improved veterinary extension services. authors’ contribution all authors included in this article are directly or indirectly participated in the planning, execution & analysis of this study. ms and td participated in data gathering, statistical analysis and writing up of the final manuscript. gh andsa participated in editing of the manuscript. am assisted the laboratory test. all authors read and accepted the final manuscript. funding this research work was funded by hawassa university. east afr. j.biophys.comput. sci. (2023), vol. 4, no. 2, 1-12 10 ethics approval and consent to participate the study was approved by college of natural and computational science research proposal review committee, hawassa university. oral informed consent was obtained for both questionnaires interview and blood sample collection to keep the privacy of specific farmers at the time of sample collection. all methods employed for this research were carried out in accordance with pertinent guidelines and regulations. competing interests authors declare no conflict of interest. acknowledgements the authors extend gratitude to hawassa university and nahdic for financial support and laboratory logistics provision. the authors are also thankful to the three district veterinary administrative farm owners and respondents who participated in this study. references abunna f., fikru s. and rufael t. 2013. sero-prevalence, of fmd at dire dawa and its surroundings, eastern ethiopia. glob. vet. 11: 575-578. asfaw w. and sintaro t. 2000.the status of fmd in ethiopia, a growing concern. addis abeba ethiopia. vet. epidemiol. newsletter 1(2): 1-5. ayelet g., gelaye e., negussie h. and asmare k. 2012. study on the epidemiology of fmd in ethiopia. rev. sci. tech. 31: 789–98. ayelet g., mahapatra m., gelaye e., gebreegziabher b., rufael t., sahle m., ferris n.p., wadsworth j., hutchings g.h. and knowles n.j. 2009. genetic characterization of fmdv, ethiopia, 1981–2007. emerging infect. dis. 15 (9):1409-1417. bayissa b., ayelet g., kyul m., jibril y. and gelaye e. 2011. study on sero-prevalence, risk factors, and economic impact of fmd in borena pastoral and agropastoral system, southern ethiopia. trop. anim. health prod. 43: 759–766. bedru h. 2006.sero-prevalence study of fmd in export bulls of borana and jimma origins unpublished dvm thesis, addis ababa university, faculty of veterinary medicine. belina d., girma b. and mengistu s. 2016.sero-prevalence of bovine fmd in selected districts of eastern showa zone, oromia regional state, ethiopia. glob. j. of sci. frontier research. 16 :79-84. berecha b., gelagay a., moses k., yasmin j. and esayas g. 2011. study on sero-prevalence, risk factors, and economic impact of foot-and-mouth disease in borena pastoral and agro-pastoral system, southern ethiopia. trop anim health prod. 43:759–66. beyene b., tolossa t., rufael t., hailu b. and tekilu t. 2015. fmd in selected districts of western ethiopia: sero-prevalence and associated risk factors. revue scientifique technique-office international des epizooties 34: 2-7. bruckner g. 2004. an evaluation of the alternatives and possibilities for countries in sub-saharan africa to meet the sanitary standards for entry into the international trade in animals and animal products. african union/interafrican bureau for animal resources, nairobi http://community.eldis. org/webx?50@248.f55ha1vgmg5.0@. ee9c4dd accessed 20th october 2020. chaosuancharoen t. 2012. experience of fmd control in thailand: the continual attempts and foresight. in key elements in the prevention and control of fmd and in implementing the strategy, in proceeding of the fao/oie global conference on fmd control. ensuring excellence and ethics of the veterinary profession, bangkok, thailand, 27–29 june 2012; fao and oie: bangkok, thailand.,121-124. chibssa t. 2006. participatory appraisal and seroprevalence study of fmd in borana pastoral system, south ethiopia. msc thesis submitted to addis ababa university, faculty of veterinary medicine, bishoftu, ethiopia. csa. 2015. federal democratic republic of ethiopia. central statistical agency, agricultural sample survey report on livestock and livestock characteristics. volume ii, 2014/15. addis ababa, ethiopia. csa. 2017. federal democratic republic of ethiopia, central statistical agency. agricultural sample survey. report on livestock and livestock characteristics. volume ii, 2016/17. addis ababa, ethiopia. desissa f., tura d., mamo b. and rufael t. 2014. epidemiological study on fmd in cattle: seraprevalence and risk factor assessment in kellem wollega zone, west ethiopia. afr. j. agric. res. 9: 1391-1395. edao b.m., hailegebreal g., berg s., zewude a., zeleke y., sori t., almaw g., adrian m., ameni g., james l. and wood n. 2018. brucellosis in the addis ababa mailto:50@248.f55ha1 east afr. j.biophys.comput. sci. 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(2024), vol. 5, issue. 2, 29-40 asrat solomon kenasew 1*, said mohammed harar1, alemitu ketema tamirat1, metadel molto1 1college of agricultural and natural resource, department of veterinary medicine, jinka university, p.o. box: 165, jinka, ethiopia keywords: attitude; bovine tuberculosis; jinka town; knowledge; practice abstract bovine tuberculosis is yet a major public health problem throughout the world, including african countries like ethiopia. limited public knowledge about the disease, coupled with negative attitudes and poor health practices, are contributing to this issue. a crosssectional study was carried out from march 2023 to july 2023 to assess the community knowledge, attitude, and practice on bovine tuberculosis in jinka town. questionnaire survey and retrospective data were used as a tool for data collection. among 382 respondents, 254 (66.5%) knew about bovine tuberculosis, whereas 128 (33.5%) respondents did not have any idea about the disease. except sex, other predictors like age, marital status, educational level and occupation were significantly associated with knowledge and preventive practices towards bovine tuberculosis. respondents had misconceptions on zoonotic importance of the disease and 95 (24.87%) respondents consume raw milk. regarding retrospective data result, among 1278 patients examined for tuberculosis, 316 (24.7%) and 5 (0.39%) were positive for pulmonary and extra pulmonary tuberculosis in 2020 g.c. during 2021 g.c, among 1066 patients examined for tuberculosis, 190 (17.8%) and 12 (1.12%) patients were positive for pulmonary and extra pulmonary tuberculosis respectively. number of patients for pulmonary and extrapulmonary were increased to 18.25% and 4% respectively in 2022 g.c. since there were misconceptions among the respondents, awareness creation and detailed investigation on the status of bovine and human tuberculosis was recommended. introduction background of the study ethiopia has 70 million cattle, 42.9 million sheep, 52.5 million goats, 2.15 million horses, 10.8 million donkeys, 0.38 million mules and 8.1 million camels (csa, 2020). despite this abundant cattle population in the country, the livestock sub-sector is generally less productive, its capacity is small, and its direct contribution bovine tuberculosis (btb) remains to be a major public health problem throughout the world, including ethiopia. the condition is worse in low income countries like ethiopia, where lower knowledge, attitude, and practice east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs assessment of community knowledge, attitude and practices toward bovine tuberculosis in jinka town, southern ethiopia *corresponding author: email: asratsolomon48@gmail.com +251-920440837 https://dx.doi.org/10.4314/eajbcs.v5i2.3s to the national economy is minimal (shitaye et al., 2007). the poor health condition of its livestock has been one of the responsible factors for the low productivity and hence profitability (giday and teklehaymanot, 2013). research article east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 29-40 30 (kap) of the publics is poor about the disease (adugna et al., 2023). bovine tuberculosis (tb) is characterized by the formation of tubercles, which are distinct granulomatous lesions in affected organs and tissues that exhibit varying degrees of calcification, necrosis, and encapsulation (thakur et al., 2020). this disease is the second main cause of death from an infection disease world-wide, after the human immunodeficiency virus (hiv). tuberculosis (tb) is one of the most serious public health issues in the world, infecting billions of people each year and ranking as the second highest cause of death from an infectious disease behind hiv/aids. in 2013, about 9 million new tb cases and 1.5 million tb deaths were estimated. about 85 percent of the disease burden is found in asia and africa (who, 2014). the tb situation has worsened over the last three decades, which can be attributed to the hiv/aids pandemic (getahun et al., 2010). mycobacterium bovis is not the major source of human tuberculosis, but humans remain susceptible to bovine tuberculosis (bulto,2012). humans can be infected primarily by ingesting the agent by drinking raw milk containing the infective bacilli, secondly, by inhaling infective droplets when there is close contact between the owner and his/her cattle, especially at night since in some cases they share shelters with their animals. in some countries, it is estimated that up to 10% of human tuberculosis are due to bovine tuberculosis (gebremedhin et al., 2014). furthermore, m. bovis can infect human when raw meat and other products from infected animals (malama et al., 2013) are consumed or by inhaling infective droplets or direct exposure to infected animals (verma et al., 2014). ethiopia has one of the world's highest rates of human tuberculosis, which is primarily caused by mycobacterium tuberculosis. it is imperative that tuberculosis positive animals must be slaughtered (culled); as soon as the initial group of reactors is removed, rigorous hygienic practices must be put in place to control the spread of infection. this involves thoroughly cleaning and disinfecting all feed troughs with a hot, 5% phenol solution. in general terms, control measures of bovine tuberculosis in the traditional extensive production systems are more difficult and complex (oie, 2009). statement of problem bovine tuberculosis is a zoonotic disease transmitted from animal to human. it induces a substantial economic impact through high cost of eradication programs and the severe consequences for movements of animals and their products, biodiversity, public health and substantial economic effect (le roex et al., 2013, rodriguez-campos, et al., 2014). zoonotic tuberculosis incidence varies across regions and countries, with higher rates observed where there is close contact between people and large cattle populations, particularly when unpasteurized milk and dairy products are frequently consumed (kock et al., 2021). ethiopia is one of the african countries where btb is considered as expanding disease in animals. diagnosis of btb in ethiopia is usually carried out on the basis of tuberculin test, meat inspection at the abattoir and rarely on bacteriological techniques (ameni et al., 2003). but researchers conducted milk borne zoonosis so far in jinka town revealed that there is still a gap in kap towards the zoonotic diseases. the kap towards btb alone was not studied in east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 29-40 31 jinka town and that is why the current research was contemplated in the study area. therefore, this study was conducted with the objective of assessing the knowledge, attitude and practices towards bovine tuberculosis in jinka town of southern, ethiopia. materials and methods description of the study area the study was conducted from march 2023 to july 2023 in jinka town which is the capital city of south omo zone. it is located in the hills north of the tama plains. currently, jinka is the center of jinka town administration. it has a latitude and longitude of 5°47′n and 36°34′e coordinates respectively and an elevation of 1490 meters above sea level. the average annual temperature and precipitation are 21.1°c and 1274 mm, respectively. it is 750 km south of the main capital city of the country, addis ababa. currently, it is one of the seats for six regional bureaus of southern ethiopia. the town has 40,311 cattle, 11,411 goats, 2868 sheep, 95,718 poultry, and 1402 equine population (jinka town agriculture office, 2023). study population the study population were individuals who are resident in jinka town with different sociodemographic characteristics. this study includes individuals of sex, different age categories, different occupation, different marital status, and those, which were found on different educational levels. besides this, the target populations were interviewed with specific questions related to knowledge, attitude, and practice of the community toward bovine tuberculosis. study design a cross-sectional study was carried out from march 2023 to july 2023 to assess the community knowledge, attitude, and practice on bovine tuberculosis in jinka town. accordingly, individuals will be selected by simple random sampling. sample size determination the study population of the current study was comprised of simple randomly selected students of different educational levels (elementary, high schools, colleges), farmers, a governmental and self-employee that are found in jinka town and its surroundings. thus, the formula given by yamane (1967) for the questionnaire survey was employed to calculate the sample size required for this study. 𝑛 = 𝑁 (1 + 𝑁 ∗ (𝑒) ) where n -sample size, n-population size = 20,267 jinka town population (jinka town finance and economic development office, 2023), e-acceptable sampling error =0.05, 95% confidence level and p= 0.05 were assumed. hence, the total sample size was calculated to be 392. method of data collection questionnaire survey a structured questionnaire was prepared to assess the knowledge, attitude, and practice of the community settled on urban and peri-urban areas of the study area. in addition, the socioeast afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 29-40 32 demographic information of each respondent was recorded. randomly selected individuals who live within the different locality of the study areas (i.e. the study population) were the target group for this study. the questionnaire was administered to the randomly selected individuals by common local language in (amharic and ari language) during the interview. there was a brief discussion on the objective of the survey and respondents were asked for their consent before administration of the questionnaire. retrospective data retrospective data (cases of tuberculosis in 3 consecutive years starting from 2020 to 2022) was collected from jinka general hospital in order to compare the prevalence of the disease and the level of the knowledge in the town. it was also important to have data of age-related cases of tuberculosis. data management and analysis all collected data were entered into the microsoft excel 2010 spreadsheet, coded and then imported to stata version-13 statistical software for descriptive statistical analysis. pearson’s chi-square (2) test was used to access knowledge, attitude and practice with their respective age, sex, education level, marital status and occupation towards bovine tuberculosis disease. in all the analysis, confidence level was held at 95% and statistical analysis was considered as significant at p<0.05 results respondents’ socio demographic characteristics the response rate was 382 (97.45%). 10 (2.55%) respondents didn’t respond for the questionnaire during the study period. among the respondents, 284 (74.3%) and 98 (25.7%) were male and female, respectively. among the age groups, adults were the dominating group with 292 (76.4%) and youths were 90 (23.6%). of the total respondents, 268 (70.2%) were married and 114 (29.8%) were unmarried, 50 (13.09%) were illiterate and 232 (86.92%) were considered as educated (table 1). table 1: socio demographic characteristics of respondents in jinka town (n=382) variables frequency percentage (%) sex male 284 74.3 female 98 25.7 age youth (15-24 yrs) 90 23.6 adult (>25 yrs) 292 76.4 marital status married 268 70.2 unmarried 114 29.8 educational level illiterate 50 13.09 primary school 116 30.37 secondary school 96 25.13 diploma, degree and above 120 31.41 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 29-40 33 knowledge of respondents on bovine tuberculosis a total of 254 (66.5%) respondents in the study area knew about bovine tuberculosis whereas 128 (33.5%) respondents haven’t heard about the disease. among the informed / knowledgeable respondents, 213 (83.86%) knew that bacteria causes bovine tuberculosis. about 80% (n=204) respondents clearly mentioned emaciation as a clinical sign of btb. among the respondents who knew about btb (n=254), 208 (81.89%) knew that bovine tuberculosis is a zoonotic disease where as 46 (18.11%) did not have any idea about its zoonotic nature. likewise, 147 (57.87%) respondents knew that ingestion of raw milk can transmit bovine tb from animal to human (table 2). table 2: knowledge of respondents regarding bovine tuberculosis (n=382) variables frequency percentage (%) know btb before yes 254 66.5 no 128 33.5 knowledge on cause of the disease (n=254) bacteria 213 83.86 parasite 11 4.33 shortage of feed 12 4.72 religion 18 7.09 clinical signs of btb (n=254) lethargy 17 6.7 coughing 31 12.2 lymph node enlargement 2 0.79 emaciation 204 80.31 zoonotic disease (n=254) yes 208 81.89 no 46 18.11 method of transmission to human (n=254) consumption of raw milk 147 57.87 consumption of raw meat 62 24.41 through cold air 26 10.24 i do not know 19 7.48 relationship between knowledge about bovine tuberculosis and the variables among 284 male and 98 female respondents, 195 (68.79%) and 59 (60.2%) were knowledgeable on btb, respectively. the remaining 31.33% males and 39.9% females did not have any idea about the disease. regarding the age groups, only 40% of the youths knew about the disease and 74.66% of the adults had good knowledge towards btb. based on educational level, 78% of illiterate respondents had poor knowledge on the disease. except sex, all independent variables (age, marital status, and educational level) considered in this study were significantly associated with the knowledge of bovine tuberculosis (p<0.05) (table 3). east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 29-40 34 table 3: relationship between knowledge on bovine tuberculosis and the variables variables number of respondents know about btb 2 pvalue yes (%) no (%) sex male 284 195 (68.67) 89 (31.33) 2.3393 0.126 female 98 59 (60.2) 39 (39.8) age youth (15-24 yrs) 90 36 (40) 54 (60) 37.0886 0.000 adult (>25 yrs) 292 218 (74.66) 74 (25.34) marital status married 268 206 (76.87) 62 (23.13) 43.5410 0.000 unmarried 114 48 (42.1) 66 (57.9) educational level illiterate 50 11 (22) 39 (78) 66.2325 0.000 primary school 116 66 (56.9) 50 (43.1) secondary school 96 56 (58.33) 40 (41.67) college level & above 120 109 (90.83) 11 (9.17) attitudes toward disease prevention among the respondents, 137 (35.86%) considered the disease prevention status in jinka town as poor and 245 (64.14%) considered it as good. among the 382 respondents, 233 (82.2%) had positive attitude towards the disease to prevent btb and the remaining 149 (27.8%) were remained with negative attitude towards btb. relation ship between educational level and preventive practices all considered preventive practices such as consumption of milk, boiling of milk, actions taken when animal and human are affected with the disease were significantly associated (p<0.05) with the educational level of the respondents (table 4). table 4: relationship between educational level and preventive practices toward btb variables educational level 2 pvalue illiterate (50) primary school (116) secondary school (96) diploma and above (120) consumption of raw milk no (287) 10 (20%) 96 (82.8%) 77 (80.2%) 104 (86.7%) 31.1480 0.000 yes (95) 40 (80%) 20 (17.2%) 19 (19.8%) 16 (13.3%) boiling of milk before consumption prevent btb yes (265) 37 (74%) 55 (47.4%) 64 (66.67%) 109 (90.8%) 52.1416 0.000 no (117) 13 (26%) 61 (52.6%) 32 (33.33%) 11 (9.2%) actions taken if human is affected with tb seek doctor (260) 40 (80%) 56 (48.28%) 58 (60.41%) 106 (88.3% 0.000 seek traditional healers (58) 7 (14%) 24 (20.69%) 18 (18.75%) 9 (7.5%) no action (64) 3 (6%) 36 (31.03%) 20 (20.84%) 5 (4.2%) actions taken if animal is affected with btb seek veterinarian (39) 39 (78%) 54 (46.55%) 58 (60.42%) 103 (85.8%) 51.7462 0.000 seek traditional healers (8) 8 (16%) 27 (23.28%) 20 (20.83%) 13 (10.8%) no action (4) 3(6%) 35 (30.17%) 18 (18.75%) 4 (3.34%) east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 29-40 35 retrospective data results retrospective data on the prevalence of pulmonary and extrapulmonary tuberculosis was collected from jinka general hospital. the data include a 3-years registered disease report of the hospital from 2020 to 2022. the data was classified in to different age and sex groups. the data revealed higher prevalence of human tuberculosis and its prevalence was higher in males. among 316 people which were positive for pulmonary tb, 163 (51.6%) were males and 153 (48.4%) were females in 2020. in 2021, there were 190 peoples from which 118 (62.1%) were males and 72 (37.9%) were females. this number was increased to 205 peoples in 2022, among which 127 (61.95%) were males and 78 (38.05%) were females. the result also indicated the presence of extrapulmonary tb in jinka town. accordingly, there were 5, 12 and 45 peoples positive for this condition during 2020, 2021 and 2022, respectively (table 5). table 5: retrospective data result based on sex groups year total examined for tb positive cases prevalence (%) type of tb male female pulmonary extra pulmonary 2020 2045 163 (51.6%) 153 (48.4%) 15.69 316 5 2021 1732 118 (62.1%) 72 (37.9%) 11.66 190 12 2022 2111 127 (61.95%) 78 (38.05) 11.8 205 45 discussion based on the detailed assessment of kap towards btb, 254 (66.5%) respondents in the study area knew about btb, while the remaining 33.5% respondents did not have any idea about the disease. this finding is higher than the finding of abebe et al. (2020) who revealed kap towards btb as 39.39% at jinka town. this difference might be due to increased provision of awareness to the community by the different stake holders and those ngos implementing their community services at the study area and the surroundings. even though, there is still a knowledge gap towards btb, the higher knowledge might be related with the recommendation of the previous study of abebe et al. (2020) who recommended awareness creation as a part of zoonotic disease prevention. the current finding is lower than the study conducted in jarso district west wollega zone, oromia region by hailu et al. (2022) who revealed that 100% participants defined tb as a disease of lung. a study conducted in gambia by boshorum et al. (2020) also revealed that most participants had heard about tuberculosis. moreover, study conducted in gambella by bati et al. (2013) revealed higher kap than the current finding. hailu et al., (2021) reported 57.2% respondents were well-informed about tb in bahir dar, amhara region ethiopia. furthermore, zeru et al. (2014) revealed that 30.8% of the respondents have good awareness about btb in mekelle town, ethiopia. this finding is lower than the findings of the current study (66.5%). the difference of kap between different regions and countries might be partly related with the difference of awareness level and it might be due to their ecological, socioeast afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 29-40 36 cultural and socio-economic differences. since the studies were implemented in different levels of urbanization where awareness creation level through media and access to internet might by different. the current study indicated that, among the knowledgeable respondents (n=254), 208 (81.89%) knew that btb is a zoonotic disease. this result was higher than the report of hailu et al. (2022) and zeru et al. (2014) who reported 24.4% and 15% respondents, respectively, agreed with the idea that tuberculosis can easily spread from animals to humans and vice versa. furthermore, wendmagegn et al. (2016) reported that 48% of the respondents in woldiya knew that btb is zoonotic. the inconsistency between different studies might be due to differences in the degree of consciousness among the participants in the study areas of concern. the predictors of the knowledge were sex, age, marital status, and educational level. males have higher knowledge (68.67%) towards btb than females (31.33%) but gender /sex was the only factor not associated with the knowledge of btb (p>0.05). there is no difference between sex groups. the current study predicted that knowledge about btb is higher in older age groups than youths. this is inconsistent with the finding of hailu et al. 2021 who revealed as knowledge about btb is higher in the age groups between 46 and 60 years. it might be suggested that elders have low level of knowledge due to limited access to training and awareness associated with btb due to different reasons. the current finding is consistent with the result of ismiala et al. (2015) who reported that age groups greater than 58 years are knowledgeable than the youngsters in nigeria. as underlined by hailu et al. (2021), knowledge increases with years of working experience. similar study by addo et al. (2011) in ghana supported this finding suggesting that herds men with long practical experiences had a greater knowledge due to past experiences on btb in their herd. ngoshe et al. (2023) also suggested that despite their lower level of education, older farmers were well-informed on animal diseases compared to younger farmers. in the current study, marital status is significantly associated (p<0.05) with the knowledge towards tb. among 268 married respondents, 206 (76.87%) were knowledgeable than the unmarried ones (42.1%). this might be due to previous experience and exposure to training. as couples are two, one of them might have awareness and they can share it together. in addition to this, in order to take care of their children, married respondents might be likely to have more access to health centers where awareness creation takes place than unmarried ones. regarding education, those who attend college (diploma level) and above have high knowledge and practice on btb as compared to those who joined primary and no formal education at all. similar findings were also reported in ethiopia by asebe and gudina (2018), kerorsa (2019) and recently by hailu et al. (2021). the study conducted in nigeria by ismaila et al. (2015) revealed similar result. as stated by asebe and gudina (2018), providing education plays a pivotal role in adding knowledge. moreover, education is an important tool in increasing awareness towards btb among livestock owners and limited access to education results in low awareness among the community. furthermore, education was among the factors east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 29-40 37 associated with better level of precautionary practice for btb. this finding is consistent with the finding of hailu et al. (2021), who revealed education as a factor which is associated with level of practice for btb. regarding the causes of btb, among the knowledgeable respondents about btb (n=254), most of the respondents 213 (83.86%) knew that bacteria cause btb. this finding is similar to buregyeya et al. (2011) in ethiopia where 79.9% of the respondents discerned the source of tb. but the current study indicated that yet 7.09%, 4.33% and 4.72% have misconception that religion, parasite and shortage of feed, respectively cause btb. onyango et al. (2020) also revealed very similar result who stated there was high misunderstanding that cold air and dust cause tb. regarding consumption of raw milk, 95 (24.87%) of respondents consume raw milk. this result is lower that the study conducted in south gondar zone by alelign et al. (2019) who reported that 69% respondents consume raw or under cooked milk and dairy products. similarly, wario et al. (2018) showed that 66.2% respondents consume raw milk in yabello. moreover, the finding of tschopp et al., (2013) from arsi zone, ethiopia revealed that 55.4% respondents consume raw milk. the study conducted in ghana by addo et al. (2011) and by ngoshe et al. (2023) in far northern kwa zulu-natal reported that 40% and 51.98% of the study participants consume raw milk respectively. this might be linked with food consumption habit and geographical difference (hailu et al., 2021). unlike the current study, most of the studies mentioned were carried out in rural and agro-pastoral areas, where raw milk consumption is likely to be practiced. according to ismaila et al. (2015), the inconsistency might be due to difference in knowledge on zoonosis and consequence of raw food consumption. educational level is among the factors significantly associated with raw milk consumption (p <0.05). the prevalence of raw milk consumption was 80%, 17.2%, 19.8% and 13.33% in illiterate, primary, secondary and diploma and above educational levels respectively. this indicates that as educational level of the respondent increases, awareness level on the consequence of raw milk consumption also increases. among 120 respondents educated to college level and above, 109 (90.8%) considered boiling milk before consumption as a preventive method of the transmission of btb from animals to humans. in another side, among 50 respondents who have no formal education, 74% respondents considered boiling milk as preventive method. this result is almost similar to the result of hailu et al., (2021) who stated that 99% of the respondents knew boiling milk prior to drinking can prevent the transmission of btb to humans. the current finding is different from that of hailu et al. 2022 and bihon et al. (2021) who indicated that more than 60% respondents disagree that pasteurization of milk before consumption prevents tb. this difference might be due the difference in the educational level of the respondents in the study areas. the retrospective data revealed that there was high prevalence of human tuberculosis in jinka town and its surroundings. this might be related with low awareness towards the transmission of btb to human and limitations to follow possible preventive measures including boiling east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 29-40 38 of milk destined for consumption. this in turn increases the frequency of raw milk consumption in the study area and the surrounding. furthermore, most tb patients fail to get treatment in the study area as there is no enough health services. almost 92% people do not come back to clinics for follow up after their first treatment because of panic of what people will say about them (onyango et al., 2020). concomitantly, this increases the transmission rate of tb to susceptible ones. the prevalence of tb was higher in males than females. among the individuals who showed-up to jinka general hospital for medical support and diagnosed positive for tuberculosis, majority of them were males. the higher prevalence of human tb in male might be related with occupational behavior, wider home range and exposure to tb patients. occupationally, females remain in the home and have low exposure to sick people and the other risk factors associated with human tb than males. conclusion & recommendation this study has identified that relatively there is good level of knowledge and moderate level of attitude and practices towards the prevention and control of the disease and yet there are misconceptions which require additional work to minimize the gap of kap among the community. this study revealed that there is high prevalence of human tuberculosis as a result of low attitude and practice towards the preventive and control measures of btb. moreover, they also have knowledge gap on the impact of consumption of raw milk and possible disease prevention strategy. analysis of the retrospective data also indicated that, there is high prevalence of human tb in the study area which is believed to be due to the above problems. it also indicates that the disease can affect all age and sex groups. based on the above conclusions, regular community awareness creation work on the possible prevention strategies of the disease, and collaborative engagement of veterinarians and physicians for the control and further investigation of the level of btb and human tb in the region are recommended. acknowledgement the authors are grateful to the jinka general hospital for provision of the 3 years retrospective data. staff members of jinka university department of veterinary medicine are also acknowledged for their direct or indirect support. references abebe f., getachew s., hailu t. and fesseha h. 2020. assessment of community knowledge attitude, and practice on milk borne zoonotic diseases in jinka, southern ethiopia. myth or fact. ann. public health res. 7: 1096. adugna g., mahendra p., ararsa b., segni a., abdi g., behera f. and mulatu n. 2023. a study on the community knowledge, attitude and practice of bovine tuberculosis in ejere town, ethiopia. int. j. clin. exp. med. res. 7(1): 1-10. addo k. k., mensah g. i. and nartey n. 2011. knowledge, attitudes and practices (kap) of herdsmen in ghana with respect to milk-borne zoonotic diseases and the safe handling of milk. j. basic appl. sci. res. 1(10):1566–1562 alelign a., zewude a., petros b. and ameni g. 2019. tuberculosis at farmer-cattle interface in the rural villages of south gondar zone of northwest ethiopia. tuberc res treat. 2019:1–8. ameni g. and wudie a. 2003. preliminary study on bovine tuberculosis in nazareth municipality abattoir of central ethiopia. bull. anim. health prod. afr. . 51: 125-132. asebe g. and gudina e. 2018. community knowledge, attitudes and practices on bovine tuberculosis and associated risk factors in gambella regional state east afr. j. biophys. comput. sci. 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(2023), vol. 4, issue. 2, 54-68 *corresponding author: email: mcmtega@yahoo.co.uk, +255-753122642 https://dx.doi.org/10.4314/eajbcs.v4i2.5s evaluation of toxicological risks and effects of microplastics on nile tilapia (oreochromis niloticus) under in vitro laboratory conditions macarius pancras mtega1*, matobola joel mihale1 and kessy fidel kilulya2 1department of physical and environmental sciences. faculty of science, technology and environmental studies. open university of tanzania 2department of chemistry, college of natural and applied sciences, university of dar es salaam keywords: microplastics; toxicological risks; oreochromis niloticus; aquatic organisms; biological effects; in vitro condition abstract microplastics have been reported by many literatures as contaminants of environmental water bodies and are ingested by aquatic organisms due to their small sizes. knowing the effects of microplastics to fresh water fish which are kept in ponds helps in managing fish keeping practice. the objective of research was to determine the toxicity of microplastics to nile tilapia (oreochromis niloticus). the experiment was done in 80 fish samples. microplastics which were prepared for the batch experiment were introduced in the aquarium followed with observation for 21 days. the digestion of fish gills and intestines involved 10 ml of 10% (w/v) koh solution and incubation at 65oc for 24 hours. engulfed microplastics were determined using stereo microscope and at-ir spectrophotometer for confirmation. engulfed microplastics were observed to be in mean range of 3.37 x 102±4.04 x 102 to 2.32 x 103 ± 3.57 x 103 particles/kg in gills and 4.68 x 104 ± 3.02 x 104 to4.40 x 104 ± 5.34 x 104 particles/kg in intestines. the observed responses were loss of equilibrium for 35% of fish, abnormal swimming for 49% of fish, abnormal ventilator behavior for 59% of fish, abnormal appearance for 39% of fish and average growth weight increase in control experiment fish was 6.10±2.62 g compared to 1.7 ± 3.62 g in test fish. there was no mortality of nile tilapia. the responses of fish to the presence of microplastics in aquarium indicated that microplastics had adverse effects to nile tilapia (oreochromis niloticus). more researches have to be done on fish physiological changes caused by microplastics. introduction plastics are produced in large amount for different applications, but have been accompanied with waste deposition in urban areas (moore, 2008; zhang, 2017). about 70 to 80% of plastic contaminants originate from anthropological activities (mvowiec, 2017). plastic wastes in environments occur in different sizes, the smallest forms are called microplastics (sadri and thompson, 2014; thakur et al., 2022). when large proportions east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 55 of plastic wastes are mismanaged, they enter the environments where they evolve into microplastics via progressive fragmentation through the process of bio-degradation, photodegradation, thermo-oxidative degradation or mechano-chemical degradation (mvowiec, 2017; guilhermino, 2021). microplastics have been found in marine biota because of their presence in ecosystems (mistri, 2022). animals exposed to microplastics under laboratory setting have shown several adverse effects like histological alterations, lesions in the gastrointestinal tract, intestinal inflammation, neurotoxicity, oxidative stress, damage, immuno-regulation, feeding behavioral change, and developmental alterations (jovanovic, 2017). oxidative stress and inflammation are caused by generated reactive oxygen species (ros) (subaramaniyam et al. 2023;yao et al., 2023). in urban areas, there are various anthropogenic activities which lead to microplastic accumulation in water bodies in which fish are found living (khan et al., 2018; mayoma et al., 2020). fish can be easily stressed due to exposure to toxic substances in water (reverter, 2018). the reported clinical signs by literatures on fish responses to abnormal water conditions have not been well documented on fresh water fish commonly known as nile tilapia (oreochromis niloticus) once exposed to microplastics. fish keeping is highly encouraged and takes place in ponds in various tropical regions in africa where tanzania is among of them. with knowledge that fresh water ponds are susceptible to microplastic pollution in urban regions, therefore there was need of finding out how far the microplastic exposure to fresh water fish, especially nile tilapia could have effect. the research was conducted to find out how fish commonly known as nile tilapia were affected by microplastics and to evaluate their effects by in vitro observation in laboratory. materials and methods materials an aquarium was made of glass (30 cm x 30 cm x 60 cm), with a capacity of 40 l. two aerators, two air and water filters, a wire mesh covering, and an aquarium fish net from the fish equipment business shop were used to support the aquarium. a laboratory thermometer and a multimeter for ph, water conductivity and total dissolved solids (tds) were obtained from the laboratory. plastic buckets, (each 20 l), and a sieve were bought from the domestic shops. fish feeds were bought from the animal feed shops. stereo microscope, hand lens, and 100 ml beakers were supplied by the laboratory. potassium hydroxide (analar compound) and standard microplastics: polyethylene (pe), polypropylene (pp), polyvinyl chloride (pvc), nylon 6, 6 and polyethylene terephthalate (pet) were supplied by precur chem and equipment ltd, tanzania. samples of fish for toxicological study samples of nile tilapia for microplastic toxicological study were collected from kibaha fish farming ponds in coast region, tanzania. the selection of this freshwater fish was based on the fact that it is commonly kept in most fish farmers in tropical regions due to the ability of withstanding extreme conditions like high temperature, change of ph or east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 56 changes of total dissolved solids. the fish have also ability to survive during transport and the period of caring and observation. small fish aged two months old (length 12 mm−14 mm and/ or weight 30 g–50 g) were captured and collected using nets. the fish were captured during the sunset and were kept in ponds within nets until early morning before sunrise where they were collected in two buckets of (20 l) each containing 10 fish. fish in one bucket was used for test experiment while in another bucket was for the control experiment. all the experiments involving fish samples were performed in batches of 20 fish and a total of 4 batch samples were collected. about 4 l of water from the pond was added in each fish bucket for maintaining fish medium. preparation and aquarium maintenance the test and control aquaria were set near the window where sun rays did not struck directly. two aerators for each aquarium were connected to the filters, and then placed in the aquarium using aquarium fish net. clean tap water was half-filled n each aquarium one day before fish introduction. the water in the aquarium was left overnight in order to dechlorinate. in the next day, aeration was performed to increase the amount of oxygen and filtration was done for half an hour to remove some suspended solids. thereafter, room temperature, ph, conductivity and total dissolved solids (tds) of the water in the aquaria and the buckets (from the fish ponds) were measured. each fish was weighed to obtain initial weight (w1) and length (l1) prior to placing in the aquarium. the fish were placed in the separate aquaria then were left to acclimatize for 20 min. then water from fish farm ponds in the buckets was mixed with dechlorinated aquarium tap water which was already in the aquarium in order to fill the left space. the purpose of retaining the pond water was to keep the association bacteria (symbiosis) used by fish in their life. lastly, each aquarium was covered with wire mesh in order to ensure fish safety. the fish in both aquaria were starved for one day, then fed with ground fish feed pellets 10% (w/w). the fish were left to acclimatize for nine days before feeding with microplastics. the fish life was maintained by continuous aeration of the aquarium water, and measuring ph, water, room temperature, conductivity and tds. the nitrate levels were controlled by dilution with 25% of clean water after every two days. the gravel was set as aquarium bed in order to trap suspended solids and feces. the feces were removed after every two days by siphoning. exposure of nile tilapia to microplastics microplastics with size of 30 µm for pvc, and 1000 µm for pet, 2000 µm for pe, 2000 µm for pp and 600 µm nylon 6,6 were mixed together in a 250 ml beaker followed with mixing with water to form a suspension. the microplastics were prepared in different concentration dose for exposure to fish; 2.7 x 107, 9.0 x 108, 1.3 x 108 and 6.7 x 107 particles/m3. the prepared micro plastic suspension was introduced in the test aquarium on the tenth day. the aquarium contained fish of average weight 40 g. then the observation was performed for 21 days according to the organization for economic co-operation and development (oecd, 2019). the behaviours (responses) of fish in the test aquarium were compared with the fish in the control aquarium. the toxic effects of east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 57 micro plastics on fish were observed by noting and recording the number of individuals affected using some established clinical signs (table 1) as stipulated in the oecd (2019). furthermore, the physical characteristics of the aquarium media (ph and conductivity), weight of fish, and concentration of microplastics were observed. table 1. clinical signs used in observation of responses of nile tilapia to microplastics exposure observation clinical sign loss of equilibrium abnormal horizontal orientation abnormal vertical orientation loss of buoyance control (floating at surface or sinking to the bottom) abnormal swimming behavior hypo activity (decrease in spontaneous activity) hyperactivity (increase in spontaneous activity) corkscrew swimming (rotation around long axis, erratic movement) abnormal surface distribution (abnormal depth selection, close to water air interface abnormal bottom distribution/behaviour abnormal depth selection, bottom of tank) over-reactive to stimulus (flight, or avoidance response to: visual, tactile touch) or vibration stimulus loss of schooling/shoaling behaviour (individual fish show, loss of aggregation and social interaction) dense schooling/shoaling behaviour (increase in clumped association of fish) abnormal ventilator (respiratory) function hyperventilation (increase in frequency of opercula ventilator movements with possible open mouth and extended opercula) hypoventilation (decreased frequency of opercula ventilator movements). coughing (fast reflex expansion of mouth and opercula not at water surface-assume to clear ventilator channels) gulping (mouth movements at water surface resulting in intake of water and air) head shaking (rapid lateral head movements) abnormal skin pigmentation darkened (malefic markings) lightened (weak pigmentation) mottled (discoloration) appearance and behaviour abnormalities oedema (abnormal swelling due to accumulation of fluids) haemorrhage (sub-mucus bleeding) faecal (anal) casts (string of faeces hanging from anus or on tank floor) source: oecd (2019). analysis of engulfed microplastics after 21 days, all fish from test and experiment aquaria were weighed for final length and weight, and then were dissected to collect intestinal parts and gills. the gills and intestines were separately digested using 10% koh solution (10% (w/v) following with incubation at 65ºc for 24 hours. later, distilled water was added to dilute the unused koh before filtration. the particles on the filter paper were washed thoroughly with water during filtration. a stereo microscope (10 x magnifications) was used to count the microplastics which was performed first by placing all microplastics in the petri-dish which had four partitions prepared by lines of east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 58 pen-ink. secondly, the petri-dish was placed on the microscope stage for visualization and counting of microplastics in all petri-dish compartments (masura et al., 2015). further confirmation of the microplastics was done using attenuated fourier transform infrared spectrophotometer instrument (at-ft-ir, bruker, massachusetts, usa). data analysis excel descriptive statistics in analysis toolpak was used to analyse row data for mean, range and standard deviation of microplastics engulfed by nile tilapia. pearson correlation was used to determine the relationship between microplastics which were engulfed and responses of nile tilapia. student t-test (n = 20)was used to determine the significant difference of effects of engulfed microplastics on nile tilapia and significant difference in growth among the microplastic fed fish (tested fish) and fish which were not fed with microplastics (non-tested fish). results water temperature, ph, total dissolved solids (tds) and electric conductivity water temperature, electric conductivity, ph and total dissolved solids were monitored as part of water quality assurance for fish growth in both test and control experiments. ammonia content in aquarium which was caused by defecation and food remains was controlled by diluting water and siphoning out after every two days of experiments. dilution and siphoning were also means of regulation of ph, tds and conductivity. the room temperature was controlled by air circulation using fans and opening windows. the room temperature therefore, ranged from 24.8 to 27ºc and water temperature ranged from 24.00 to 26.00 ºc. the temperature range was within the water quality requirement for fish farming, which is 24ºc to 30ºc (ezeanya et al., 2015). the water conductivity (mean ± standard deviation) in tested fish had changed by 62% (465 ±117.15 µs/cm) from the pond water conductivity (750±254 µs/cm), the ph had changed by 0.9% (6.8 ± 0.4) from the pond ph (6.7 ± 0.2) and tds had changed by 63.9% (236.5 ±32.4 ppm) from the pond tds (370.0 ± 127.3 ppm). the water conductivity in non-tested fish had changed by 64% (480 ± 80.1 µs/cm) the pond water measurements were 750±254 µs/cm (electric conductivity), ph had changed by 0.9% (6.8 ± 0.2) from the pond ph, 6.7 ± 0.2, and total dissolved solids had changed by 72% (269.75 ±104.85 ppm) from the pond tds, 370.0 ± 127.3 ppm. there was no significant difference between water conductivity (t-test, p = 0.7, df = 40), total dissolved solids (t-test, p = 0.09, df = 40), and ph (t-test, p = 0.05, df = 40) in test and control experiments. the recommended ph range for fish growth is 6−9, electric conductivity is 100−2000 µs/cm (ezeanya et al., 2015) while total dissolved solids is 500 ppm−1500 mg/l (scannell and jacobs, 2001). microplastic abundance and wet weight change of nile tilapia microplastics were found in both intestines and gills of the tested fish in great abundance. polyvinyl chloride microplastics were the most abundant because of the size (30 µm) which was smaller than other microplastic sizes. other microplastics with size 600 µm to 2000 µm were not determined in both gills east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 59 and intestines. the microplastic concentrations in intestines were in concentration range of 4.68 x 103 ± 3.02 x 103particles/kg to 4.40 x 104±5.34 x 104 particles/kg (mean ± standard deviation) and in gills with concentration range of 3.37 x 102 ± 4.04 x 102particles/kg to 2.32 x 103 ± 3.57 x 103 particles/kg (table 3). the wet weight concentration (mean ± standard deviation) increase for test fish was 1.7± 0.66–3.66±0.74g and for non-test fish was 5.2 ± 1.85–6.54 ± 2.11 g. the results indicated that the non-test fish had great increase in wet weight compared to test fish (table 2) although the statistical comparison (one way-anova) indicated that there was no significant difference in growth changes (df = 79, p = 0.9) between test fish and nontest fish. the change in growth length was high in non-test fish. there was significant difference (p˂0.05, p = 0.00, t-test) in the effects of microplastics among test fish, also there was medium correlation (r = 0.3, p = 0.00) between microplastic effects on fish weight changes. the change in growth weight of test fish gave scattered cycles which were underlying straight line to show linear relationship between the two variables. the relationship between growth weight change and microplastics did not depend on concentration of microplastics, which means even low concentration could affect negatively the fish growth (figure 1). figure 1. relationship between (a) growth change in weight and microplastic concentration (b) growth length change and microplastic concentration the change in growth length of test fish had a range of 0.1 ± 0.06 to 1.21 ± 1.16 cm (mean ± standard deviation) compared to the non-test which had range of 0.62±0.12 to 1.7±1.0 cm (table 2). the mean length growth change in test fish was smaller compared to non-tested fish because of some fish which had fin rot which resulted to loss of tails. the results indicated that there was small correlation (r= 0.1, p = 0.00) between microplastic effects on fish length changes. the change in growth length of tested fish gave scattered cycles which were underlying straight line to show linear relationship between the two variables. the relationship between growth length east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 60 change and microplastics did not depend on concentration of microplastics. table 2. engulfed microplastics in gills and intestines and fed microplastics and comparison of mean change in fish weight (g), change in fish length (cm) between tested and non-tested fish in relation to the engulfed mps (particles/kg) 1. engulfed microplastics (mean ± standard deviation) in gills and intestines together with fed microplastics exp exposed ps/m3 gills, particles/kg intestines 1 2.7 x 107 3.37 x 10 2±4.04x102 4.68 x 103±3.02 x 103 2 9.0 x107 9.95 x 102±9.70 x 102 5.50 x 103±9.31 x 103 3 1.3 x 108 1.79 x 103±1.88 x 103 4.40x 104±5.34 x 104 4 6.7 x 108 2.32x 103±3.57 x 103 1.08 x 104±1.00 x 104 2. comparison of (mean ±standard deviation) change in fish weight (g), change in fish length (cm) between tested and non-tested fish in relation to the (mean ±standard deviation) engulfed microplastics (particles/kg) exp change weight change in length engulfed particles tested fish non-test fish tested fish non-test fish 1 1.75 ±0.66 5.2 ±1.88 0.46±0.42 0.65±0.34 5.03x103±3.07x103 2 3.66 ±0.74 6.54 ±2.11 0.6±0.18 0.62±0.12 3.58x103±9.94x103 3 2.53 ±2.9 6.52 ±2.32 1.21±1.16 0.8±0.5 4.59x104±5.36x104 4 1.7 ±3.62 6.10 ±2.62 0.1±0.06 1.7±1.0 2.33x104±3.85x104 mean 2.41±0.92 6.09±0.54 0.57±0.49 0.95±0.53 1.94x104±1.71x104 biological effects of microplastics on nile tilapia the microplastic effect was found in the fourth day from the test initiation. the fish which were tested with microplastics and indicated loss of equilibrium were 4±1 fish (mean ± standard deviation), abnormal swimming behavior were 4±2 fish, abnormal ventilatory function were 6 ± 4 fish and abnormal external appearance were 3±2 fish (table 3). table 3. the number (mean ± standard deviation) of nile tilapia which had positive responses on microplastic exposure and the observed clinical signs. observation abnormal clinical sign number of fish loss of equilibrium horizontal orientation 4 ± 2 vertical orientation 4 ± 2 loss of buoyancy control 4 ± 2 swimming behavior hypo activity 4 ± 4 hyperactivity 5 ± 4 surface distribution 6 ± 4 bottom distribution 2 ± 4 dense schooling 8 ± 1 ventilatory/respiration function hyperventilation 9 ± 2 hypoventilation 1 ± 2 irregular ventilation 6 ± 2 gulping 9 ± 4 abnormal skin pigmentation lightened 1 ± 2 external appearance excess mucus secretion 5 ± 6 faecal casts (anal) 1 ± 1 fin rot 3 ± 4 east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 61 some tested fish with difficulty in ventilation by gulping behaviour and selection of space aggregated in one space near the aquarium wall, and some fish had fin rot compared to the non-tested fish without microplastics. however, results did not involve any mortality cases of fish because they were not observed in experiments. the no observable effect concentration (noel) was assumed to correspond to the highest concentration tested which was 4.40 x 104 particles/kg similar to the report by hasselerharm (2022). evaluation of microplastic toxicity on nile tilapia the percentage of fish which had abnormal external appearance was high, followed by abnormal swimming behaviour, abnormal ventilatory function and lastly loss of equilibrium (figure 2). key: btc is for butch number figure 2. percentage of fish with their response to microplastics the loss of equilibrium was determined by observing fish which had shown clinical signs, namely abnormal horizontal orientation, abnormal vertical orientation and loss of buoyance which was in 35% of fish. the percentage of fish which had shown loss of equilibrium gave scattered cycles which were underlying straight line to show linear relationship between the two variables. the relation to engulfed microplastics had a large negative correlation coefficient, r = -0.7, p = 0.14. therefore, there was a large relationship between percentage of fish which had loss of equilibrium and the engulfed microplastics (figure 3). east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 62 figure 3. relationship between fish with abnormal appearance and concentration of engulfed microplastics the abnormal swimming in fish was observed in 48.1% of fish. the clinical signs which were observed in fish for abnormal swimming were: hypo activity, abnormal bottom distribution and dense schooling or shoaling. the percentage of fish which had abnormal swimming indicated relationship with engulfed microplastics (figure 3), where the clustered cycles were close to the straight line. the correlation coefficient, r = 0.9, p = 0.14 indicated presence of large relationship between the percentage of fish with abnormal swimming and engulfed microplastics. abnormal ventilation in test fish was observed in 58.8% of fish. the clinical signs for abnormal ventilation observation were: hyper ventilation and hypoventilation. the percentage of fish which had abnormal ventilation indicated a relationship with number of engulfed microplastics (figure 3) east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 63 where the clustered cycles were close to the straight line. the correlation coefficient, r = 0.4, p = 0.13 indicated the presence of medium correlation between percentage of fish with abnormal ventilation and engulfed microplastics. abnormal appearance of test fish was not observed in 38.5%. the clinical signs were; oedema, fin rot, and excessive mucus on epidermal part. the clustered cycles were close to the straight line to show close relationship between percentage of fish with abnormal appearance and engulfed microplastics (figure 3). the correlation coefficient, r = -0.17, p=0.13 indicated small relationship between percentage fish with abnormal appearance and engulfed microplastics. figure 4. responses of fish to microplastic exposure in four different experiments the responses of fish on exposure to microplastics was monitored daily and results indicated that the percentage of tested fish which had positive responses started within day 3 to day 5 from the day microplastics were introduced, then increased to the maximum in 10 days (figure 4). among the fish which were exposed to microplastics, 72.5% of them had small weight and 75% had smaller length growth compared to fish which were not exposed to microplastics. the observation was made for daily increase of wet weight in both tested fish and non-tested fish. east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 64 the daily wet weight increase in tested fish was low compared to the nontested fish (figure 5). figure 5. change in wet weight of oreochromis niloticus with days for tested fish and non-tested fish in two different experiments. discussion the temperature conditions which were used in keeping fish for study were in the normal range which is required for fish farming and did not differ much from the temperature 17.7ºc to 27.7ºc used by chaudhary and sharma (2018) in the experiment for tilapia in fish tank. water electric conductivity, total dissolved solids, and ph were within the limit of water quality requirements where ph is 6.09.0 for freshwater fish, tds upper limit is 1500 ppm, although the one that causes effect is 5000−10,000 ppm (scannel and jacobs, 2001). one report by chaudhary and sharma (2018) for fresh water fish kept in the tank, indicated that water was kept alkaline with ph range of 8.3−8.50 in both control and test tanks and the water electric conductivity was 1730µs/cm–1980 µs/cm, the conditions which were different from what used in this study but both were within the limits of freshwater fish growth. in this study, it was found that microplastics concentrated in gills and intestines the scenario which indicates that the test fish in aquarium could not manage eliminating particles of microplastics during taking in water through gills, and eating food. events like these have been reported also in other studies for microplastics in marine biota because of presence in ecosystems (thompson et al., 2009). the responses of nile tilapia on exposure to microplastics in this study have been reported as fish stress caused by toxic contaminants of water in many literatures (coyle, 2004; davidson et al., 2011; reverter, 2018; sridhar, 2021). cocci et al. (2022) reported that microplastic occurrence in fish was found to be correlated with antioxidant enzymes (catalase and superoxide dismutase) and cytokinases (interleukin 1 ß, 10 and east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 65 interferon) levels, causing reactive oxygen species (ros) generation and immune cell infiltration in the gut. moreover the study by alimba and faggio (2019) indicated that microplastic presence in marine vertebrates produces oxidative stress in proteins, lipids and deoxyribonucleic acid (dna) by altering the antioxidant defuse mechanisms, i.e. enzyme catalase (cat), superoxide dismutase (sod), glutathione-s-transferase (gst), glutathione peroxidase (gpx) and reduced glutathione (gsh) genes at the catalytic and transcriptional levels. they regulate the gene expression that controls oxidative stress by acting as pro-oxidant stimuli activating antioxidant gene expression through nuclear factor erythroid 2–related factor 2(nrf2)dependent mechanism. the clinical signs like abnormal swimming which was observed in nile tilapia in this study has been reported also by wright et al. (2020) who had observed that the polyvinyl chloride which were exposed to brown trout had reduced swimming activity and there was change in their circadian rhythms. furthermore, the report by tang et al. (2018) indicated that microplastic exposure in sea bream heads altered the jnk (c-jun n-terminal kinase) and erk (extracellular signal-regulated kinase) signalling pathways which are involved in the detoxification process of fish. even other abnormal behaviours observed in nile tilapia in this study might be attributed to the similar situation as yao et al. (2023) reported for the exposed high concentration of polystyrene microplastics in golden pompano (trachinotus ovatus) which had caused oxidative damage and up-regulation of genes (grpn78, x6p-1, and elf-2α), resulting in endoplasmic reticulum stress (ers) and severe oxidative stress which raised the bax/bcl-2 ratios and induced death. more studies report similar cases of microplastic exposure effects although they do not mension directly the clinical signs which have been considered in our observation in nile tilapia but the oxidative stress must be the reason. for instance; the study by cao et al. (2023) reported the effects of polyethylene microplastics in carp and found that they elevated the expression of p53, nf-kb, p6s, 1kkα, 1kkß, caspase-3 genes in the gills. also the extended exposure to polystyrene microplastics in coach juveniles (paramisgurnus dabbyanus) was studied by wang et al. (2022) and found to inhibit the expression of keep 1-nrf2 signalling pathway genes inducing aptosis by upgrading proteins (p53, gadd 45 ba and caspase 3b) expressions, also were found to up-regulate tnf-α and ptgs2a which are gene markers in the inflammatory mechanism in zebra fish (umamaheswari et al., 2021). lastly, the study by chen et al. (2021) on tilapia had found that polyethylene microplastics caused oxidative stress in the liver by damaging cell membrane increasing lipid peroxidation (plo) levels, in the brain, dorsal muscles and gills, higher brain activity where 32% of the fish had microplastics in the dorsal muscle (barboza et al., 2020). in addition poor quality of water that was contributed by presence of microplastic contamination might have lead also to diseases that rise from bacteria and fungi. because fouling organisms like fungi and bacteria can easily attach to microplastics causing them to be agents of diseases (dekiff et al., 2014). furthermore, responses indicated by clinical signs in this study have also been observed in other studies for effects of toxin east afr. j. biophys. comput. sci. (2023), vol. 4, no. 2, 54-68 66 contamination where 30% to 35% of individual fish responded positively for example some had frequent surface movement with gulping of air (islam et al., 2021), the abnormal alterations were associated with physiological responses which were inductive of stress. conclusion and recommendation the test fish engulfed microplastics which were found in intestines and gills. the engulfed microplastics resulted to stress in nile tilapia which was observed from different responses according to clinical signs and the lag in proper growth. there were no mortality of nile tilapia but the responses to presence of microplastics in aquarium indicated that microplastics had adverse effects to nile tilapia. the evaluation of toxicity of microplastics to nile tilapia indicated that fish in contaminated ponds have high susceptibility to the effect of microplastics which might lead to death if the conditions have not been controlled. although there have been reports on the effects of microplastics as a cause of oxidative stress to fish, more studies need to be done to give clear description for some observations like fin rot and abnormal mucus secretion responses which might be associated to microplastic harbouring microorganism in large amount. acknowledgement: authors would like to thank the laboratory technicians of open university of tanzania and university of dar es salaam for their great support in laboratory activities and instrumental analysis. references alimba c.g. and faggio c. 2019. microplastics in the marine environment: current trends in environmental pollution and mechanisms of toxicological profile. environ. toxicol. pharmacol. 68: 61–74. doi:10.1016/j.etap.2019.03.001 barboza l.g.a., lopes c., oliveira p., bessa f., otero v. and henriques b. 2020. microplastics in wild fish from north east atlantic ocean and its potential for causing neurotoxic effects, lipid oxidative damage, and human health risks associated with ingestion exposure. sci. total environ. 717, 134625. doi:10.1016/j.scitotenv.2019.134625 cao j., xu r., wang f., geng y., xu t. and zhu m. 2023. polyethylene microplastics trigger cell apoptosis and inflammation via inducing oxidative stress and activation of the nlrp3 inflammasome in carp gills. fish shellfish immunol. 132, 108470. doi:10.1016/j.fsi.2022.108470 chen q., li m., li l., li j., li y. and luo y. 2021. polyethylene microplastics cause oxidative stress and dna damage in the liver of tilapia (oreochromis niloticus). environ. pollut. 272, 115964. doi:10.1016/j.fsi.2022.09.022 cocci p., gabrielli s., pastore g., minicucci m., mosconi g. and palermo f.a. 2022. microplastics accumulation in gastrointestinal tracts of mullus barbatus and merluccius is associated with increased cytokine production and signaling. chemosphere 307, 135813. doi:10.1016/j.chemosphere.2022.135813 coyle s.d, durborow r.m. and tidwell j.h. 2004. anaesthetics in aquaculture. southern regional agricultural centre. srac publication no. 3900. davidson j., good c., welsh c. and summerfelt s.t. 2011. abnormal swimming behaviour and increased deformities in rainbow trout oncorhynchus mykiss cultured in low exchange water recirculating aquaculture systems. aquac. eng. 45: 109–117 dekiff j.h., remy d., klasmeier j. and fries e. 2014. occurrence and spatial distribution of microplastics in sediments from norderney. environ. pollut. 186, 248e256. ezeanya n.c., chukwuma g.o, naigwe k.n. and egwuonu c.c. 2015. standard water quality management strategies for fish farming (a case study of otamiri river). int res j eng technol.. eissn: 2319-1163 pissn: 2321-7308 guilhermino a.b, martins a., lopes c., raimundo j., vieira l., gabriel a., barboza, costa j., antunes c., caetano m. and vale c. 2021. microplastics in east afr. j. biophys. comput. sci. 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(2023), vol. 4, no. 2, 54-68 68 transport. environ. int. 136, 105411. doi:10.1016/j.envint.2019.105411 yao f.c., gu y., jiang t., wang p.f., song f.b. and zhou z. 2023. the involvement of oxidative stress mediated endoplasmic reticulum pathway in apoptosis of golden pompano (trachinotus blochii) liver under ps-mps stress. ecotoxicol. environ. saf. 249, 114440. doi:10.1016/j.ecoenv.2022.114440 zhang h. 2017. transport of micropalstics in coastal seas. estuarine, coastal and shelf science 199:77-86. eajbcs__volume_4_issue 2_ article 5__macarius et al_ evaluation of toxicological risks and effects of microplastics on nile tilapia.pdf (p.61-76) admasu tadesse *1 , sirkumar acharya 2, berhanu belay3 1 department of mathematics, hawassa university, ethiopia 2 department of mathematics, kiit university, bhubaneswar, india 3department of mathematics, debretabor university, ethiopia keywords: multi-objective programming; triangular fuzzy number; fuzzy transportation problem; fuzzy decision variables; ranking function; fuzzy programming method. abstract the aim this study is presenting the solution methodology of multiobjective fuzzy transportation problem with fuzzy decision variables, where all the input parameters and decisions variables of the programming problems are assumed to be triangular fuzzy number and triangular fuzzy decision variables respectively. moreover the objectives under considerations are minimization of cost of transportation and minimization of shipping time under fuzzy environment. the fuzziness of the objective functions and the fuzzy constraints of the programming problem are defuzzified using the ranking function and the equality property between two fuzzy numbers, respectively. the consequent crisp multi-objective fuzzy transportation problem is tackled by employing fuzzy mathematical programming approach. finally fuzzy decision is made after solving the resultant mathematical programming problem using lingo(schrage and lindo systems (1997)) software. illustrative numerical example is presented in support of the proposed methodology. the transportation of a product manufactured at different plants ( supply origins) to a number of different warehouses (demand destinations). transportation problems were well known as a basic network problem in its classical category. the formulation and discussion of transportation model was introduced by hitchcock (1941). classical tp models and techniques have been effectively applied to problems with a well-defined or accurately known parameters for many years. the coefficient parameters of the majority of tp models are considered *corresponding author: east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs college of natural & com h pu aw tat as ion sa u al n sc ive ie r nc sit e y s year 2021 volume xx no xx email: admasut@hu.edu.et transportation problem(tp) is a particular class of linear programming, which is associated with day-to-day activities in our real life and mainly deals with logistics. it helps in solving problems on distribution and transportation of resources from one place to another. the goods are transported from a set of sources (e.g., factory) to a set of destinations (e.g., warehouse) to meet the specific r equirements, das et al. (2016). inother words, transportation problems deal with _______________________________ https://dx.doi.org/10.4314/eajbcs.v4i2.4s east afr. j. biophys. comput. sci. (2023), vol. 4, issue. 2, 43-53 43 introduction fuzzy programming approach to solve multi-objective fully fuzzy transportation problem research article to be single real number which is accurately known. however, such assumptions are not suitable for dealing with a number of issues that occur in real life because many of the parameters are imprecise and vague as a result of both natural and anthropogenic effects. this motivates to formulate the tp models in uncertain environment. one of the uncertain environments is fuzzy environ-ment. moreover in most of the literatures, authors assumed the decision parameters as fuzzy numbers while the decision variables as crisp ones. since the variables are crisp, the solution obtained as the crisp, which is a real number. the solution is exact value in the fuzzy programming problems with fuzzy parameters. the fuzzy aspect of the decision is partly lost in this case so, it is reasonable and important to consider fuzzy mathematical programming problem with fuzzy decision variables. fuzzy transportation problems involving fuzzy decision variables are considered in this study. kaur and kumar (2012) studied a special type of fuzzy tp by assuming that a decision maker is uncertain about the precise values of transportation cost only, where the transportation cost is represented by generalized trapezoidal fuzzy numbers. in their proposed work all the supply and demand of products are crisp parameters that means there is no uncertainty about the supply and demand of the product. according to the explanation of kumar and kaur (2011), there may be factors which imposes the occurrences of fuzziness in tp. some of these are, the decision maker has not enough information about the unit transportation cost of transportation operation and thus the transportation cost uncertain, there may be some sort of vagueness with respect to the demand of a newly introduced product to the market and there exists uncertainty about the product availability at a source or supplier because of time factor. many authors introduced tools to solve tp. since transportation problem (tp) is special case of linear programming (lp) problem, one straightforward approach is to apply the existing lp techniques to the fuzzy tp. these techniques are discussed by many researchers namely; buckley (1988), buckley (1990), mitlif (2016), ebrahimnejad (2013), ebrahimnejad (2015), etc. however, some these techniques only give crisp solutions, which represent a compromise in terms of fuzzy data. the traditional view on tp is mainly concerned with distributing any homogeneous product from a group of supply centers, called sources, to any group of receiving centers, called destinations, in such a way as to minimize the single objective total transportation cost, where the transportation cost per unit product is constant regardless of the amount transported, but most of the time in real-life situation, the tps are not designed as single objective function. the tp that deals with multiple-objective functions is called a multi-objective transportation problem (motp). the motp is a special type of multi-objective linear programming problem in which objective functions conflict with each other. furthermore, objective functions are frequently in conflict, thus there is no one best (global optimum) solution, but rather a group of equally good (non-dominated) alternatives known as pareto optimal (po) solutions. in the framework of multi-objective programming problems, numerous scholars from a wide variety of academic disciplines discussed their work. recently, multi-objective problems have been proposed by researchers such as sayyah et al. (2019); sahih et al. (2021); sosa and dhodiya (2021); geshniani et al. (2020), and others. researchers namely; acharya et al. (2014) and dutta et al. (2016) introduced mot problem in stochastic environment. chakraborty and chakraborty (2010) discussed cost-time minimization tp, where the demand, supply and transportation cost per unit of the quantities are fuzzy. nomani et al. (2017) introduced a weighted goal programming to solve multiobjective transportation problems with crisp parameters. they used weighted approach based on goal programming to obtain compromise solutions. roy et al. (2018) proeast afr. j. biophys. comput. sci. (2023), vol. 4, issue. 2, 43-53 44 posed multi-objective transportation problem (motp) under intuitionistic fuzzy environment. they have assumed transportation cost, the supply and the demand parameters as a intuitionistic fuzzy numbers. jalil et al. (2017) proposed a solution approach for obtaining compromise optimal solution of fully fuzzy(all the parameters and decision variables are fuzzy) multi-objective solid transportation problems. in their proposed problem they used ranking function for the defuzzification of fuzzy objective function and the property of equality between fuzzy numbers for the defuzzification of fuzzy constraints. el sayed and abo-sinna (2021); moges et al. (2023); malik and gupta (2022); niksirat (2022), etc. are the works done under fuzzy environment. as is mentioned above (paragraph 2), in most of the literature, authors regarded the decision variables as being crisp while the decision parameters are assumed to be fuzzy. this assumptions leads to crisp decisions which is illogical. a fuzzy decision multiobjective fully fuzzy transportation problem proposed in this study. ranking function and equality between two triangular fuzzy numbers are employed for defuzzification purpose and finally the equivalent crisp multi-objective model is solved fuzzy programming method. the paper is organized as follows: following the introduction, basic preliminaries are presented in sect. 2. the mathematical model of multi-objective fuzzy tp is presented in sect. 3. solution procedures are provided in 4. numerical examples are provided in support of the proposed method in sect. 5. finally, conclusion is provided in sect. 6 followed by supportive references. definition: [roy et al. (2018)]: a tri-angular fuzzy number ã is denoted by (ap, a, ao), where ap, a, ao are real numbers. the membership function (µã(x)) of ã is given below: µã(x) =  0, x ≤ ap x−ap a−ap , ap ≤ x ≤ a ao−x ao−a , a ≤ x ≤ ao 0, otherwise note: the point ’a’ is the core value of triangular fuzzy number ã, where µã(a) =1 ap and ao are the lower and upper bounds of support of triangular fuzzy number ã respectively. definition : [roy et al. (2018)]: let ã = (ap, a, ao) and b̃ = (bp, b, bo) be two triangular fuzzy numbers ,then (i) (ap, a, ao)⊕(bp, b, bo) = (ap+ap, a+b, ao+ bo) (ii) k(ap, a, ao) = (kap, ka, kao), k ≥ 0 (iii) (ap, a, ao)⊗ (bp, b, bo) = (apbp, ab, aobo, if ap ≥ 0 and bp ≥ 0 definition : [ebrahimnejad (2017)]: let ã = (ap, a, ao) and b̃ = (bp, b, bo) be two triangular fuzzy numbers ,then (i) ã = b̃ iff ap = bp, a=b and ao = bo (ii) ã = (ap, a, ao) ≥ 0 iff ap ≥ 0 definition :ebrahimnejad (2017)]: fuzzy tp is said to be balanced transportation problem when total supply from all the sources is equal to the total demand in all destinations. definition : [kumar et al. (2011)]: a ranking function is a function r:f (r) → r, where f(r) is a set of fuzzy numbers defined on set of real numbers, which maps each fuzzy number into the real line, where a natural order exists. let ã = (ap, a, ao) be a triangular fuzzy number, then r(ã) = ap+2a+ao 4 definition : [hasan et al. (2015)]: multi-objective optimization problem (moop) involves more than one objective function that are to be minimized or maximized. answer of moop is the set of solutions that define t he b est t radeoff between competing objectives. the following is general mathematical form of moop: east afr. j. biophys. comput. sci. (2023), vol. 4, issue. 2, 43-53 45 basic preliminaries max /min zm(x),m = 1, 2, 3, ...,m (2.1) s.t. gj(x) ≥ 0, j = 1, 2, ..., j (2.2) hk(x) ≥ 0, k = 1, 2, ..., k (2.3) xl ≤xi ≤ xu (2.4) the mathematical model for moftp with fuzzy decision variables is represented as: min : z̃k ≈ m∑ i=1 n∑ j=1 ((ckij) pxp ij, c k ijxij, (c k ij) oxo ij), k ∈ {1, 2...k} (3.1) subject to n∑ j=1 (xp ij, xij, x o ij) ≈ (api , ai, a o i ), i ∈ {1, 2, 3, ...,m} (3.2) m∑ i=1 (xp ij, xij, x o ij) ≈ (bpj , bj, b o j), j ∈ {1, 2, 3, ..., n} (3.3) x̃ij ⪰ 0, i ∈ {1, 2, 3, ...,m}; j ∈ {1, 2, 3, ..., n} (3.4) where, i. the fuzzy total availability and fuzzy total demand are assumed to be equal(balanced fuzzy transportation problem), ′m′ is total number of supply points and ’n’ is total number of destination points, ii. ãi=(api , ai, a o i ) is the fuzzy availability of the commodity at ith origin and assumed to be triangular fuzzy number, iii. b̃j=(bpj , bj, b o j) is the fuzzy requirement of the commodity at jth destination and assumed to be triangular fuzzy number, iv. c̃ij=(cpi j, cij, c o i j) is the fuzzy cost coefficient involved with fuzzy variables in the objective function from ith origin to jth destination, which is also assumed to be triangular fuzzy number, v. x̃ij=(xp ij, xij, x o ij) is the fuzzy quantity that should be transported from ith origin to jth destination and assumed to be triangular fuzzy decision variables. crisp equivalent of multiobjective fuzzy transportation problem since fmp model from (3.1) to (3.4) cannot be solved directly, so ranking function and the property of equality between the fuzzy numbers are respectively applied on the fuzzy objective functions and fuzzy constraints models of moftp. the resultant crisp equivalent is obtained as: min : zk = 1 4 m∑ i=1 n∑ j=1 ((cpij) kxp ij+2ckijxij+(coij) kxo ij), k = 1, 2.....k (3.5) subject to n∑ j=1 xp ij = api , i ∈ {1, 2, 3, ...,m}; (3.6) n∑ j=1 xij = ai, i ∈ {1, 2, 3, ...,m} (3.7) east afr. j. biophys. comput. sci. (2023), vol. 4, issue. 2, 43-53 46 mathematical model n∑ j=1 xo ij = aoi , i ∈ {1, 2, 3, ...,m} (3.8) m∑ i=1 xp ij = bpj , j ∈ {1, 2, 3, ..., n} (3.9) m∑ i=1 xij = bj, j ∈ {1, 2, 3, ..., n} (3.10) m∑ i=1 xo ij = boj , j ∈ {1, 2, 3, ..., n} (3.11) xo ij−xij ≥ 0, i ∈ {1, 2, 3, ...,m}, j ∈ {1, 2, 3, ..., n} (3.12) xij−xp ij ≥ 0, i ∈ {1, 2, 3, ...,m}, j ∈ {1, 2, 3, ..., n} (3.13) xp ij ≥ 0, i ∈ {1, 2, 3, ...,m}, j ∈ {1, 2, 3, ..., n} (3.14) solution procedure now we use the fuzzy programming programming technique to solve the crisp multiobjective programming problem of 3.5 to 3.14. the solution procedures based on the fuzzy programming method is detailed below. step 1: find the ideal solutions x1, x2, ..., xk by picking one objective function at a time and leaving the other objective functions. step 2: construct a pay-matrix with the help of individual best solutions found by the above step. using table 1 estimate the bounds of zk (k=1,2,3...,k) from the payoff matrix. step 3: for every objective function zk (k=1,2,3...,k), we formulate membership function using any one of the following techniques of maximization or minimization: table 1: payoff matrix z1(x) z2(x) . . . zk(x) x(1) z1(x (1)) z2(x (1)) . . . zk(x (1)) x(2) z1(x (2)) z2(x (2)) . . . zk(x (2)) . . . . . . . . . . . . . . . . . . . . . x(k) z1(x (k)) z2(x (k)) . . . .zk(x (k)) step 4 case 1: membership function is formulated in the case of maximization problem as: µzk(x) =  0, if zk ≤ lb−k zk−lb−k ub∗−lb−k , if lb−k ≤ zk ≤ ub∗k 1, if zk ≥ ub∗k where lb−k denotes the worst lower bound of zk and ub∗k denotes the best upper bound of zk case 2: for minimization problem the membership function is formulated as: µzk(x) =  0, if zk ≥ ub−k ub−−zk ub−−lb∗k , if lb∗k ≤ zk ≤ ub−k 1, if zk ≤ lb∗k where ub−k denotes the worst upper bound of zk and lb∗k denotes best lower bound of zk. case 1 : apply the augmented variable, λ with max-min operator to formulate a crisp single objective mixed integer programming problem as: max : λ (3.15) subject to µzk(x) ≥ λ, k = 1, 2, ...k (3.16) n∑ j=1 xp ij = api , i ∈ {1, 2, 3, ...,m} (3.17) east afr. j. biophys. comput. sci. (2023), vol. 4, issue. 2, 43-53 47 n∑ j=1 xij = ai, i ∈ {1, 2, 3, ...,m} (3.18) n∑ j=1 xo ij = aoi , i ∈ {1, 2, 3, ...,m} (3.19) m∑ i=1 xp ij = bpj , j ∈ {1, 2, 3, ..., n} (3.20) m∑ i=1 xij = bj, j ∈ {1, 2, 3, ..., n} (3.21) m∑ i=1 xo ij = boj , j ∈ {1, 2, 3, ..., n} (3.22) xo ij−xij ≥ 0, i ∈ {1, 2, 3, ...,m}, j ∈ {1, 2, 3, ..., n} (3.23) xij−xp ij ≥ 0, i ∈ {1, 2, 3, ...,m}, j ∈ {1, 2, 3, ..., n} (3.24) xp ij ≥ 0, i ∈ {1, 2, 3, ...,m}, j ∈ {1, 2, 3, ..., n} (3.25) 0 ≤ λ ≤ 1 (3.26) case 2 : apply the augmented variable, λ with min-max operator to formulate a crisp single objective mixed integer programming problem as: min : λ (3.27) subject to µzk(x) ≤ λ, k ∈ {1, 2, 3, ....k} (3.28) n∑ j=1 xp ij = api , i ∈ {1, 2, 3...m} (3.29) n∑ j=1 xij = ai, i ∈ {1, 2, 3...m} (3.30) n∑ j=1 xo ij = aoi , i ∈ {1, 2, 3...m} (3.31) m∑ i=1 xp ij = bpj , j ∈ {1, 2, 3...n} (3.32) m∑ i=1 xij = bj, j ∈ {1, 2, 3...n} (3.33) m∑ i=1 xo ij = boj , j ∈ {1, 2, 3...n} (3.34) xo ij−xij ≥ 0, i ∈ {1, 2, 3...m}; j ∈ {1, 2, 3...n} (3.35) xij−xp ij ≥ 0, i ∈ {1, 2, 3...m}; j ∈ {1, 2, 3...n} (3.36) xp ij ≥ 0, i ∈ {1, 2, 3...m}; j ∈ {1, 2, 3...n} (3.37) 0 ≤ λ ≤ 1 (3.38) step 5 at the end, the equivalent single objective mp model is solved by using appropriate techniques or existing software. the obtained po solutions substituted back to original fuzzy objective function, as the result we can find fuzzy optimal values of each fuzzy objective functions. numerical example in this part, application numerical example is solved using the provided approach, and the conclusions drawn from the results are discussed in further detail. a firm has two sources o 1 and o 2 and three destinations d1 ,d2 and d3. the fuzzy supply of the commodity from o1 and o2 are (75, 95, 125) and (45, 65, 95), respectively. request of fuzzy demanded product at d1 ,d2 and d3 are (35, 45, 55), (25, 35, 45) and (60, 80, 110), respectively. the company wants to determine the fuzzy quantity of the commodity that should be transported from each origin to each destination so that the total fuzzy transportation cost is minimum with minimum transfer time. for i=1,2, j=1,2,3., let the fuzzy transportation cost for unit quantity of the commodity from ith source to jth destinations be c̃ij , the fuzzy transportation time is also considered as t̃ij and x̃ij represents the allocations(or amounts), which is non negative triangular fuzzy real variable. the theoretical data on fuzzy cost of transportation and fuzzy delivery time, is given in the table 2 below. east afr. j. biophys. comput. sci. (2023), vol. 4, issue. 2, 43-53 48 table 2: fuzzy transportation cost per unit(in rupees) and fuzzy transportation time per unit(in minute) d1 d2 d3 c̃1j(o1) (15,25,35) (55, 65,85) (85,95,105) c̃2j(o2) (65,75,85) (80,90,110) (30,40,50) t̃1j(o1) (4, 6, 8) (6, 8,10) (7,9,11) t̃2j(o2) (3,5,7) (5,7,9) (11,13,15) from the table 2 mathematical model for moftp with fuzzy decision variables becomes: min : z̃1 ≈ (15, 25, 35)⊗ x̃11 ⊕ (55, 65, 85)⊗ x̃12 ⊕ (85, 95, 105)⊗ x̃13 ⊕ (65, 75, 85)⊗ x̃21 ⊕(65, 75, 85)⊗ x̃21 ⊕ (80, 90, 110)⊗ x̃22 ⊕ (30, 40, 50)⊗ x̃23 (3.39) min : z̃2 ≈ (4, 6, 8)⊗ x̃11 ⊕ (6, 8, 10)⊗ x̃12 ⊕ (7, 9, 11)⊗ x̃13 ⊕ (3, 5, 7)⊗ x̃21 ⊕ (5, 7, 9)⊗ x̃22 ⊕(11, 13, 15)⊗ x̃23 (3.40) subject to x̃11 ⊕ x̃12 ⊕ x̃13 ≈ (75, 95, 125) (3.41) x̃21 ⊕ x̃22 ⊕ x̃23 ≈ (45, 65, 95) (3.42) x̃11 ⊕ x̃21 ≈ (35, 45, 65) (3.43) x̃12 ⊕ x̃22 ≈ (25, 35, 45) (3.44) x̃13 ⊕ x̃23 ≈ (60, 80, 110) (3.45) x11, x̃12, x̃13 ⪰ 0 (3.46) x̃21, x̃22, x̃23 ⪰ 0 (3.47) defuzzification is done using the concept discussed in the subsection 3.1. then the case(3.27-3.37) of evaluation of membership functions for the minimization (max-min operator) is applied on the crisp motp along with all the procedures discussed above. the fuzzy programming method is applied on the aforementioned crisp equivalent motp to find the ideal solutions as detailed below x(1) = (xp 11, x11, x o 11, x p 12, x12, x o 12, x p 13, x13, x o 13, x p 21, x21, x o 21, x p 22, x22, x o 22x p 23, x23, x o 23)= (35,35,55,10,10,10,30,50,60,0,10,10,15,25,35,30,30,50) x(2) = (xp 11, x11, x o 11, x p 12, x12, x o 12, x p 13, x13, x o 13, x p 21, x21, x o 21, x p 22, x22, x o 22, x p 23, x23, x o 23)= (0,10,30,25,35,35,50,50,60,35,35,35,0,0,10,10,30,50) at the corresponding ideal points the values of crisp objective functions are obtained and given as: z1=10737.5, z2=1440. after constructing a pay-of matrix 2, the bounds of the two objective functions are given by: 10737.5 ≤ z1(x) ≤ 11825 1440 ≤ z2(x) ≤ 1465. the the single objective crisp problem is obtained by formulating membership function. thus the programming problem becomes: max : λ (3.48) east afr. j. biophys. comput. sci. (2023), vol. 4, issue. 2, 43-53 49 subject to z1 + 1387.5λ ≤ 11825 (3.49) z2 + 25λ ≤ 1465 (3.50) xp 11 + xp 12 + xp 13 = 75 (3.51) x11 + x12 + x13 = 95 (3.52) xo 11 + xo 12 + xo 13 = 125 (3.53) xp 21 + xp 22 + xp 23 = 45 (3.54) x21 + x22 + x23 = 65 (3.55) xo 21 + xo 22 + xo 23 = 95 (3.56) xp 11 + xp 21 = 35 (3.57) x11 + x21 = 45 (3.58) xo 11 + xo 21 = 65 (3.59) xp 12 + xp 22 = 25 (3.60) x12 + x22 = 35 (3.61) xo 12 + xo 22 = 45 (3.62) xp 13 + xp 23 = 60 (3.63) x13 + x23 = 80 (3.64) xo 13 + xo 23 = 110 (3.65) xo ij − xij ≥ 0 (3.66) xij − xp ij ≥ 0 (3.67) xp ij ≥ 0 (3.68) 0 ≤ λ ≤ 1 (3.69) by employing the lingo software, the resultant equivalent crisp programming problem (3.48)-(3.69) is solved. the po solutions and the agumated variable λ obtained are given consecutively as: x∗=(31.66375,41.66375,61.66375,0,3.336248,3.33666248,43.33675,50,60, 3.336248 ,3.336248 ,3.336248 ,25,31.66375,41.66375,16.66375,30,50), λ=0.6668124. the compromising fuzzy objective functions values are z̃1=(6875.31, 10341.77, 16075.04) and z̃2=(748.32, 1355.13, 2335). figurative description of fuzzy optimal triangular cost and triangular transfer time are detailed in the figure below. figure 1: minimum fuzzy transportation cost east afr. j. biophys. comput. sci. (2023), vol. 4, issue. 2, 43-53 50 figure 2: minimum fuzzy transfer time the defuzzified crisp motp is solved by fuzzy programming method. using max-min operator, the resultant single objective crisp integer mp problem is coded into lingo optimization package version 19.0 software and fuzzy po solutions are obtained. the minimum total fuzzy cost of transportation and the minimum fuzzy transfer time are obtained and interpreted as follows: fuzzy transportation cost and fuzzy transfer time z̃1=(6875.31, 10341.77, 16075.04) and z̃2=(748.32, 1355.13, 2335) respectively are calculated by back substitutions of po solutions into fuzzy objective functions (3.1) of the the programming problem. it is found that the least amounts of minimum total transportation cost and transfer time are 6875.31 and 748.32 units respectively. the the most possible amounts of minimum total transportation cost and transfer time are 10341.77 and 1355.13 units respectively. furthermore, the greatest amounts of minimum total transportation cost and total transfer time are 16075.04 and 2335 units respectively. the classical transportation problem (tp) is primarily concerned with distributing any homogeneous product from a group of supply centers, known as sources, to any group of receiving centers, known as destinations, in such a way that the single objective total transportation cost is minimized, where all parameters are crisp (precisely defined). however, in many circumstances, the decision maker lacks precise knowledge of the tp parameters. and the nature of the tps are not designed as single objective function. if the nature of the information is vague and the decision maker objectives preference are conflicting, t he c orresponding programming problem is fuzzy multi-objective programming problem, and thus fuzzy motp arises. in this paper, we have discussed a solution approach for solving tp, with more than one objective function by considering the presence of vagueness in the real life data of transportation problems, where all the parameters and decision variables are considered as triangular fuzzy numbers. initially, the fuzzy objective functions are defuzzified by applying the ranking function for trianeast afr. j. biophys. comput. sci. 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(2023), vol. 4, issue. 2, 43-53 53 east afr. j. biophys. comput. sci. hawassa university introduction mathematical model crisp equivalent of multi-objective fuzzy transportation problem solution procedure numerical example discussion of the results conclusion basic preliminaries untitled tinaw tilahun asmamaw1, kiros gebrearegawi kebedow2,∗ 1department of mathematics, mezan tepi university, ethiopia 2department of mathematics, hawassa university, ethiopia keywords covid-19; protection; stability analysis; forward bifurcation; sensitivity analysis; optimal control abstract ∗ east afr. j. biophys. comput. sci. (2024), issue 5, no. 2, 58-86 58 in this paper, we propose a mathematical model to investigate coronavirus diseases (covid-19) transmission in the presence of protected and hospitalized classes. we establish that the solution of the dynamical system remains positive and bounded. we compute the disease free equilibrium point and analyze the stability behavior of the steady state solutions.we determine the basic reproduction number (r0)and demonstrate that the disease fades away when r0 < 1but persists in the population when r0 > 1. the center manifold theory is used to assess the local stability of the endemic equilibrium. the model demonstrates a forward bifurcation, and a sensitivity analysis is conducted. the sensitivity analysis reveals that r0 is highly influenced by the protection rate, highlighting the necessity of maintaining a high level of protection along with hospitalization to effectively control the disease. we develop optimal strategies for protection and hospitalization. the characterization of the optimal control is derived using pontryagin’s maximum principle. numerical results for the dynamics of the covid-19 outbreak and its optimal control show that a combination of protection and hospitalization is the most effective strategy for reducing the spread of covid-19 within the population.. portation lemecha obsu and feyissa balcha (2020). the novel coronavirusnow referred to as covid-19 is caused by severe acute respiratory syndrome (sars-cov-2) and consists of single-stranded ribonucleic acid (rna) structure sohrabi et al. (2020). the novel coronavirus is mainly spread 1. introduction coronavirus disease 2019 (covid-19) is an infectious disease caused by a newly discovered coronavirus gurmu et al. (2020). the new virus was first appeared late december 2019 in the chinese city of wuhan and eventually invaded the world due to fast modern air transa mathematical model for the transmission dynamics of covid-19 pandemic considering protected and hospitalized with optimal control corresponding author email address: kirosg@hu.edu.et +251926528484 https://dx.doi.org/10.4314/eajbcs.v5i2.5s research article east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 59 from person to person, through respiratory droplets, the spread is more likely when people are within 6 feet of each other toquero (2020). there is no known curing medicine to combat the covid-19 pandemic. standard recommendations by the who to prevent the spread of covid-19 include frequent cleaning of hands using soap or alcohol-based sanitizer, covering the nose and mouth with a flexed elbow or disposable tissue when coughing and sneezing and avoiding close contact with anyone that has a fever and cough toquero (2020). mathematical modeling in epidemiology helps to understand the fundamental mechanisms that drive the spread of disease, while also offering insights into potential control strategies.the model formulation process clarifies the assumptions, variables, and parameters involved. furthermore, models offer conceptual insights such as thresholds, basic reproduction numbers, contact numbers, and replacement numbers.mathematical models and computer simulations are useful experimental tools for building and testing theories, assessing quan-titative conjectures, answering specific ques-tions, determining sensitivities to changes in parameter values, and estimating parameters from data brauer et al. (2019). the first m athematical m odel w as developed by daniel bernoulli allen et al. (2008) on pandemic of smallpox by introducing two systems of ordinary differential e quations. he assumed that recovery from infection confers immunity (no re-infection). he also assumed that the probability that infected individuals for the first time die does not depend on those who survive from the infection. he showed that inoculation was advantageous if the associated risk of dying was less than 11%. a number of compartmental models have been proposed and analyzed for the covid19 outbreak in different c ountries. i n particular, yang and wang yang and wang (2020) proposed a mathematical model for covid-19 incorporating multiple transmission pathways, including both human-tohuman and environment-to-human transmission routes. global stability was analysed using lyapunov function. the authors employed a bilinear incidence rate based on the law of mass action and fitted the model with the data of wuhan city of china and estimated the reproduction number. in 2020, haileyesus and getachew alemneh and telahun (2020) proposed a conceptual seir model to study the pandemic covid-19 transmission in ethiopia. global stability was analysed using lyapunov function. additionally, they incorporated timedependent controls into the basic model and extended it to an optimal control framework for the disease. an optimal control problem was formulated and analyzed using pontryagin’s maximum principle. however, none of the authors cited here are considering protected and hospital-ized classes with optimal controls. thus we are improved the existed model, by including the protected and hospitalized classes with optimal controls. the remainder of the paper is organized as follows. in section 2 we provided the description of the problems and its mathematical model formulation. section 3 gives details the qualitative analysis of the model. the numerical analysis of our model is presented in section 4, furthermore we present the extensions of the model to optimal controls and its numerical simulations 5 and 6. finally, section 7 concludes the paper. 2. mathematical model formulation 2.1. the modified mathematical model in this subsection, we modify the existing seir model to study the transmission dynamics of covid-19 infection in a population. the model is a modification of what is presented in alemneh and telahun (2020). in the present model we extended seir model by including protected and hospitalized classes. 2.2. model formulation we formulate a mathematical model to investigate coronavirus diseases (covid-19) transmission in the presence of protected and hospitalized classes. the model divides the total population into six sub-classes according to their disease status. susceptible (s), protected (p), exposed (e), infected (i), hospitalized (h) and recovered (r). the following assumptions have been used in the formulation of the model: 1. the population under study is heterogeneous and varying with time. 2. all recruited human population is susceptible. 3. susceptible individuals who keeping social distancing, using an alcohol-based hand sanitizer and wearing face masks progress into protected class. 4. protected individuals cannot acquire infection of covid-19 disease due to proper use of an alcohol-based hand sanitizer, wearing face masks and keeping social distancing. 5. the latently infected individuals (exposed) could infect other people with a higher probability than people in the infected class. since exposed individuals show no symptoms and can easily spread the infection to other people with close contact, often in an unconscious manner. 6. transmission through human-to-human route is alone considered. other means of transmission are ignored. 7. we assume that individuals have no permanent immunity after recovery from the disease, that is the recovered individuals have a chance to be susceptible again. 8 the natural mortality rates are assumed to be the same for all the compartments. 9. all parameters in the model being nonnegative. we consider the force of infection λ which is given by λ = β(σ1i + σ2e + σ3h), (1) where β is the effective contact rate, while σ1, σ2 and σ3 are the relative infectiousness parameters associated with the infected, exposed and hospitalized classes respectively. variables description of the state variables s susceptible individuals p protected individuals, who keeping social distancing, using an alcohol-based hand sanitizer and wearing face masks properly to protect themselves from the virus e latently infected individuals, who have no symptoms of covid-19 virus disease but are capable of infecting others i infected individuals, who have active covid-19 virus disease and can infect other people h hospitalized individuals, who are admitted to health care facility or isolated in their home due to virus infection active cases r recovered individuals the flow chart of the modified model is illustrated in figure (1). east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 60 table 1: the state variables and their descriptions. table 2: parameters of the modified model and their descriptions. parameter description of the parameter π recruitment rate of susceptible θ protection rate of susceptible individuals ν waning rate of protected individuals to susceptible class β effective contact rate σ1 modification parameter for relative infectiousness of infected individuals σ2 modification parameter for relative infectiousness of exposed individuals σ3 modification parameter for relative infectiousness of hospitalized individuals δ the exposed progression rate τ proportion of exposed individuals who join infected class 1− τ the progression from exposed individuals to recovered class α hospitalization rate of infected individuals µ natural death rate ρ disease-induced death rate of infected individuals ξ disease-induced death rate of hospitalized individuals ε rate of recovery of the individuals from infected class γ recovery rate of hospitalized patients ω waning immunity rate η the proportion of recovered individuals that become susceptible 1− η the progression from recovered individuals to protected class figure 1: the flow chart for the modified model of covid-19 pandemic. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 61 based on our assumptions and the flow chart (1), the modified model for the transmission dynamics of covid-19 is given by the following deterministic system of non-linear differential equations: ds dt = π+ ηωr + νp − β(σ1i + σ2e + σ3h)s − (θ + µ)s, (2a) dp dt = θs + (1− η)ωr− (ν + µ)p, (2b) de dt = β(σ1i + σ2e + σ3h)s − (δ + µ)e, (2c) di dt = τδe − (α+ ε+ µ+ ρ)i, (2d) dh dt = αi − (γ + µ+ ξ)h, (2e) dr dt = (1− τ)δe + εi + γh − (ω + µ)r, (2f) with non-negative initial conditions s(0) = s0 > 0, p (0) = p0 ≥ 0, e(0) = e0 ≥ 0, i(0) = i0 ≥ 0, h(0) = h0 ≥ 0 and r(0) = r0 ≥ 0. 3. qualitative analysis of the modified model in this section, we present some basic qualitative properties of the modified model. these analysis include finding t he s et i nside which the model can be sufficiently studied (i .e., the invariant region); local and global stability of equilibrium points of the model (2). 3.1. well-posedness since all the functions on the right hand side of the system (2) are continuously differentiable. thus, the existence and uniqueness of the solutions is established by the picard’s theorem valcher (2002). now, we show the positivity and boundedness of solutions. theorem 3.1. (positivity) if s(0) > 0, p (0) ≥ 0, e(0) ≥ 0, i(0) ≥ 0, h(0) ≥ 0 and r(0) ≥ 0, then the solution (s(t), p (t), e(t), i(t), h(t), r(t)) of the dynamical system (2) is non-negative for all time t ≥ 0. proof. to show the positivity of the solution of the dynamical system (2), we will perform the proof by using contradiction. we assume that s(t) ≤ 0 for some t ≥ 0, that is there exists small t0 > 0 such that s(t0) = 0, s ′(t0) ≤ 0 and s(t) > 0 for t ∈ [0, t0). then p (t) ≥ 0, e(t) ≥ 0 and i(t) ≥ 0 for t ∈ [0, t0]. if this be not the case, there exists option-i: t1 ∈ [0, t0] such that p (t1) = 0, p ′(t1) < 0 and p (t) > 0 for t ∈ [0, t1). then e(t) ≥ 0 and i(t) ≥ 0 for t ∈ [0, t1]. option-ii: t2 ∈ [0, t1] such that e(t2) = 0, e ′(t2) < 0 and e(t) > 0 for t ∈ [0, t2). then p (t) ≥ 0 and i(t) ≥ 0 for t ∈ [0, t2]. option-iii: t3 ∈ [0, t2] such that i(t3) = 0, i ′(t3) < 0 and i(t) > 0 for t ∈ [0, t3). then p (t) ≥ 0 and e(t) ≥ 0 for t ∈ [0, t3]. it follows from equation (2d) that we have i ′(t3) = τδe(t3)− (α+ ε+ µ+ ρ)i(t3). this implies that i ′(t3) = τδe(t3) ≥ 0. this is a contradiction. integration of equation (2e) leads to h(t) = e−(γ+µ+ξ)t ( h(0) + α ∫ t 0 i(s)e(γ+µ+ξ)sds ) ≥ 0, for t ∈ [0, t2]. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 62 then e ′(t2) = β(σ1i(t2)+σ3h(t2))s(t2) ≥ 0. this is a contradiction. hence h(t) ≥ 0 for every t ∈ [0, t1]. integration of equation (2f) leads to r(t) = e−(ω+µ)t ( r(0) + ∫ t 0 ((1− τ)δe(s) + εi(s) + γh(s)) e(ω+µ)sds ) ≥ 0, for t ∈ [0, t1]. then p ′(t1) = θs(t1) + (1 − η)ωr(t1) ≥ 0. this is a contradiction. hence r(t) ≥ 0 for every t ∈ [0, t0]. thus s ′(t0) = π + ηωr(t0) + νp (t0) > 0, but this leads to a contradiction to the assumption that s ′(t0) ≤ 0. therefore, the solutions s(t), p (t), e(t), i(t), h(t), r(t) in the system (2) remain positive for all t > 0. this completes the proof. theorem 3.2. (boundedness) there exists a positively invariant region ω in which the solution (s(t), p (t), e(t), i(t), h(t), r(t)) of the dynamical system (2) is bounded. proof. the positivity has already been established by theorem (3.1). for this model the total population is n(t) = s(t)+p (t)+e(t)+ i(t) +h(t) +r(t). then, we obtain: dn dt = π− µn − (ρi + ξh). this implies that dn dt ≤ π− µn, since the solution i(t) and h(t) are positive. solving the differential inequality we get the relation, n(t) ≤ π µ + ( n(0)− π µ ) e−µt, if n(0) ≤ π µ , then we obtain 0 ≤ n(t) ≤ π µ , for all t ≥ 0. if n(0) ≥ π µ , then we have 0 ≤ n(t) ≤ n(0), for all t ≥ 0. thus, the feasible solution set of the system (2) remain in the region ω = { (s, p,e, i,h,r) ∈ r6 + : 0 ≤ n(t) ≤ max ( n(0), π µ )} . if we start with initial data n(0) ∈ ω, then the solution n(t) ∈ ω, for every t > 0. this shows the positively invariance of ω. thus, the solution of the dynamical system (2) is bounded. 3.2. steady state the steady states of the system (2) are solutions of the following equations: 0 =π + ηωr + νp − β(σ1i + σ2e + σ3h)s − (θ + µ)s 0 =θs + (1− η)ωr− (ν + µ)p 0 =β(σ1i + σ2e + σ3h)s − (δ + µ)e 0 =τδe − (α + ε+ µ+ ρ)i 0 =αi − (γ + µ+ ξ)h 0 =(1− τ)δe + εi + γh − (ω + µ)r. there are at most two steady states for the system (2): the disease free equilibrium e0 and endemic equilibrium e1. the disease-free equilibrium point of our model is obtained by setting the disease state variables e = 0, i = 0 and h = 0. thus, the disease free equilibrium point is given by e0 = ( s0, p 0, e0, i0, h0, r0 ) = ( π(ν + µ) µ(θ + ν + µ) , πθ µ(θ + ν + µ) , 0, 0, 0, 0 ) . the existence of the endemic equilibrium point depends on the basic reproduction number r0 and will be presented later. 3.3. basic reproduction number the basic reproduction number, which is denoted by r0, and defined as the average number of secondary infections produced by a single infected individual in a completely suseast afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 63 ceptible population. using the next generation matrix method diekmann et al. (2010), the basic reproduction number r0 can be calculated from the relation r0 = ρ(fv −1). let f be the vector for the newly infected and v be the vector for the transfer of individuals into and out of the infected compartments. let x = (e, i,h), then we obtain: f(x) =  β(σ1i + σ2e + σ3h)s 0 0  and v(x) =  (δ + µ)e (α + ε+ µ+ ρ)i − τδe (γ + µ+ ξ)h − αi  . the jacobian matrix to f and v are f = [ ∂fi(e0) ∂xj ] =  βσ2s 0 βσ1s 0 βσ3s 0 0 0 0 0 0 0  , v = [ ∂vi(e0) ∂xj ] =  δ + µ 0 0 −τδ k1 0 0 −α k2  , where k1 = α + ε+ µ+ ρ and k2 = γ + µ+ ξ. the next-generation matrix fv −1 is given by fv −1 =  r1 +r2 +r3 βs0(σ1k2+σ3α) k1k2 βσ3s0 k2 0 0 0 0 0 0  , where r1 = βσ2s0 δ + µ , r2 = βσ1s0τδ k1(δ + µ) and r3 = βσ3s0τδα k1k2(δ + µ) . (3) we find the eigenvalues of fv −1 by solving the characteristic equation |fv −1 − λi| = 0 as λ1 = r1 +r2 +r3, λ2 = 0 and λ3 = 0. the basic reproduction number r0 is the spectral radius (the largest eigenvalues in modulus) of fv −1 which is given by r0 = ρ(fv −1) = r1 +r2 +r3. the parts r1, r2 and r3 represent the contributions from the human-to-human transmission routes (exposed-to-susceptible, infectedto-susceptible and hospitalized-to-susceptible individuals, respectively). we can rewrite the basic reproduction number as follows: r0 = πβ(ν + µ) µ(θ + ν + µ)(δ + µ) ( σ2 + σ1τδ α + ε+ µ+ ρ + σ3τδα (α + ε+ µ+ ρ)(γ + µ+ ξ) ) . (4) 3.4. local stability of disease free equilibrium theorem 3.3. the disease free equilibrium point e0 of the system (2) is locally asymptotically stable if r0 < 1 and unstable if r0 > 1. proof. the jacobian matrix of the system (2) at the disease-free equilibrium e0 is given by j(e0) =  −(θ + µ) ν −βσ2s 0 −βσ1s 0 −βσ3s 0 ηω θ −(ν + µ) 0 0 0 (1− η)ω 0 0 βσ2s 0 − (δ + µ) βσ1s 0 βσ3s 0 0 0 0 τδ −k1 0 0 0 0 0 α −k2 0 0 0 (1− τ)δ ε γ −(ω + µ)  . east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 64 the matrix j(e0) is an upper triangular block matrix. its eigenvalues are λ1, λ2, λ3, λ4, λ5 and λ6. where λ1, λ2 are eigenvalues of the first block matrix of j(e0) and λ3, λ4, λ5, λ6 are eigenvalues of the fourth block matrix of j(e0). the first block matrix of j(e0) given by j1(e0) = [ −(θ + µ) ν θ −(ν + µ) ] . we find the eigenvalues of j1(e0) by solving the characteristic equation |j1(e0)−λi| = 0 as λ1 = −µ and λ2 = −(θ + ν + µ). the fourth block matrix of j(e0) is given by j4(e0) =  βσ2s 0 − (δ + µ) βσ1s 0 βσ3s 0 0 τδ −k1 0 0 0 α −k2 0 (1− τ)δ ε γ −(ω + µ)  . thus the eigenvalues λ3, λ4, λ5, λ6 are obtained from the characteristic equation of j4(e0): (−(ω + µ)− λ)[λ3 + ((δ + µ)(1−r1) + k1 + k2)λ 2 + [k1(δ + µ)(1− (r1 +r2)) +k2(δ + µ)(1−r1) + k1k2]λ+ k1k2(δ + µ)(1−r0)] = 0. from this equation, we obtain the values for λ to be λ3 = −(ω + µ) and the eigenvalues λ4, λ5, λ6 are the roots of the cubic polynomial: p(λ) = a0λ 3 + a1λ 2 + a2λ+ a3 = 0, where a0 = 1, a1 = (δ + µ)(1−r1) + k1 + k2, a2 = k1(δ + µ)(1− (r1 +r2)) + k2(δ + µ)(1−r1) + k1k2, a3 = k1k2(δ + µ)(1−r0). furthermore, a1a2 − a3 = k1(δ + µ)2(1−r1)(1− (r1 +r2)) + k2(δ + µ)2(1−r1) 2 + k1k2(δ + µ)(1−r1) +k21(δ + µ)(1−r0) + k1(k1 + k2)[k1(δ + µ)r3 + k2(δ + µ)(1−r1) + k1k2]. if r0 < 1, then r1, r2, r3 and r1 +r2 are strictly less than one. since r0 = r1+r2+r3. the coefficients a1, a2 and a3 are positive and a1a2 > a3 if r0 < 1. thus, all the eigenvalues of j(e0) are negative. it follows by routh-hurwitz criteria that the disease free equilibrium e0 is locally asymptotically stable for r0 < 1. if r0 > 1, then a3 is negative and the routh-hurwitz criterion tells that the disease free equilibrium e0 is unstable. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 65 3.5. global stability of disease free equilibrium theorem 3.4. for r0 < 1, the disease free equilibrium e0 of the system (2) is globally asymptotically stable if s0 ≥ s. proof. let us rewrite our model system (2) as dz1 dt = f (z1, z2), dz2 dt = g(z1, z2), g(z1, 0) = 0. where z1 = (s, p,r) ∈ r3 + represents the class of uninfected individuals and z2 = (e, i,h) ∈ r3 + represents the class of infected individuals. the disease free equilibrium point of the model is denoted by u0 = (z∗ 1 , 0), where z∗ 1 = ( π(ν+µ) µ(θ+ν+µ) , πθ µ(θ+ν+µ) , 0 ) . since the disease free equilibrium point is locally asymptotically stable (see theorem (3.3) ), to prove global stability, we will apply the castillo-chavez theorem castillo-chavez et al. (2002). from system (2), we have dz1 dt = f (z1, z2) =  π+ ηωr + νp − β(σ1i + σ2e + σ3h)s − (θ + µ)s θs + (1− η)ωr− (ν + µ)p (1− τ)δe + εi + γh − (ω + µ)r  , dz2 dt = g(z1, z2) =  β(σ1i + σ2e + σ3h)s − (δ + µ)e τδe − (α + ε+ µ+ ρ)i αi − (γ + µ+ ξ)h  . i. to show z∗ 1 is globally asymptotically stable for the system dz1 dt = f (z1, 0), let us consider the reduced system dz1 dt = f (z1, 0) =  π+ ηωr + νp − (θ + µ)s θs + (1− η)ωr− (ν + µ)p −(ω + µ)r  . (5) we can rewrite the system (5) as: ds dt = −(θ + µ)s + νp + ηωr +π, (61) dp dt = θs − (ν + µ)p + (1− η)ωr, (62) dr dt = −(ω + µ)r, (63) east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 66 and admits as solutions s(t) = π(ν + µ) µ(θ + ν + µ) + 1 θ + ν [( ν(s(0) + p (0) +r(0))− πν µ ) e−µt + ( θs(0)− νp (0) + ω(ν − η(θ + ν)) θ + ν − ω r(0)− πθ θ + ν + µ ) e−(θ+ν+µ)t ] − (ν − ηω) θ + ν − ω r(0)e−(ω+µ)t, p (t) = πθ µ(θ + ν + µ) + 1 θ + ν [( θ(s(0) + p (0) +r(0))− πθ µ ) e−µt − ( θs(0)− νp (0) + ω(ν − η(θ + ν)) θ + ν − ω r(0)− πθ θ + ν + µ ) e−(θ+ν+µ)t ] − (θ − (1− η)ω) θ + ν − ω r(0)e−(ω+µ)t, r(t) = r(0)e−(ω+µ)t. taking the limit as t goes to ∞, we obtain (s(t), p (t), r(t)) → ( π(ν + µ) µ(θ + ν + µ) , πθ µ(θ + ν + µ) , 0 ) = z∗ 1 . therefore, z∗ 1 is globally asymptotically stable for the system dz1 dt = f (z1, 0). ii. we will show that g(z1, z2) = az2 − ĝ(z1, z2), ĝ(z1, z2) ≥ 0 for (z1, z2) ∈ ω where a = ∂g ∂z2 (z∗ 1 , 0) is a metzler matrix (the off diagonal elements of a are non-negative) and ω is the region where the model makes biological sense. consider a matrix a = ∂g ∂z2 (z∗ 1 , 0) =  βσ2s 0 − (δ + µ) βσ1s 0 βσ3s 0 τδ −(α + ε+ µ+ ρ) 0 0 α −(γ + µ+ ξ)  . hence, a is a metzer matrix (off diagonal elements are non-negative). here, ĝ(z1, z2) = az2 −g(z1, z2). after some simplification, we obtain ĝ(z1, z2) =  βσ2e(s 0 − s) + βσ1i(s 0 − s) + βσ3h(s0 − s) 0 0  , ĝ(z1, z2) = (s0 − s)  β(σ2e + σ1i + σ3h) 0 0  ≥ 0. therefore by castillo-chavez theorem castillo-chavez et al. (2002), the disease free equilibrium point e0 of the system (2) is globally asymptotically stable for r0 < 1. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 67 3.6. endemic equilibrium point endemic equilibrium point is a steady state solution where the disease persists in the population. in the presence of disease in the population, there exist an equilibrium point called endemic equilibrium point denoted by e1 = (s∗, p ∗, e∗, i∗, h∗, r∗). it can be obtained by setting each equation of the system (2) equal to zero. then we obtained s∗ = s0 r0 , p ∗ = θs0k + (1− η)ωµδ(θ + ν + µ)[(1− τ)k1k2 + ετk2 + γατ ]s0(r0 − 1) (ν + µ)kr0 , e∗ = k1k2µ(ω + µ)(θ + ν + µ)s0(r0 − 1) kr0 , i∗ = k2δµτ(ω + µ)(θ + ν + µ)s0(r0 − 1) kr0 , h∗ = αδµτ(ω + µ)(θ + ν + µ)s0(r0 − 1) kr0 , r∗ = δµ(θ + ν + µ)[(1− τ)k1k2 + ετk2 + γατ ]s0(r0 − 1) kr0 , where k = k1k2[µ(ν + µ)(ω + δ + µ) + δµ(1− η)ω] + ωδτ(ηµ+ ν)[α(µ+ ξ) + k2(µ+ ρ)], provided that r0 > 1. from this we see that for the endemic equilibrium to exist r0 > 1. moreover, the force of infection can be updated as λ∗ = β(σ1i ∗ + σ2e ∗ + σ3h ∗). (7) when we substitute the expression for e∗, i∗ and h∗ into the force of infection λ∗, we obtain λ∗ = µk1k2(δ + µ)(ω + µ)(θ + ν + µ)(r0 − 1) k , (8) provided that r0 > 1. from this, we see that, there is no endemic equilibrium of the system (2) if r0 < 1. therefore, this condition shows that it is not possible for backward bifurcation in this model. hence we have established the following result. 3.7. local stability of endemic equilibrium theorem 3.6. the endemic equilibrium e1 of the system (2) is locally asymptotically stable theorem 3.5. a unique endemic equilibrium point e1 = (s∗, p ∗, e∗, i∗, h∗, r∗) exists and is positive if r0 > 1. when we plot the force of infection λ∗ over r0 by using the expression for λ∗ we got a forward bifurcation in figure (2). if r0 > 1. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 68 proof. to determine the local stability of endemic equilibrium, we used the center manifold theory castillo-chavez and song (2004), by taking β as a bifurcation parameter. we make the following change of variables on the system (2). let s = x1, p = x2, e = x3, i = x4, h = x5 and r = x6. moreover, by using vector notation x = (x1, x2, x3, x4, x5, x6) t , the system (2) can be written in the form dx dt = f (x), with f = (f1, f2, f3, f4, f5, f6) t . we choose β = β∗ as a bifurcation parameter. solving for β∗ from r0 = 1, we obtain β∗ = µ(θ + ν + µ)(δ + µ)(α + ε+ µ+ ρ)(γ + µ+ ξ) π(ν + µ)[σ2(α + ε+ µ+ ρ)(γ + µ+ ξ) + σ1τδ(γ + µ+ ξ) + σ3τδα] . the jacobian matrix of the system (2) evaluated at the disease free equilibrium e0 with β = β∗ is given by j∗ =  −(θ + µ) ν −β∗σ2s 0 −β∗σ1s 0 −β∗σ3s 0 ηω θ −(ν + µ) 0 0 0 (1− η)ω 0 0 β∗σ2s 0 − (δ + µ) β∗σ1s 0 β∗σ3s 0 0 0 0 τδ −k1 0 0 0 0 0 α −k2 0 0 0 (1− τ)δ ε γ −(ω + µ)  , where k1 = α + ε+ µ+ ρ, k2 = γ + µ+ ξ. the jacobian matrix j∗ of the linearized system has a simple zero eigenvalue with all other eigenvalues having negative real part, hence the center manifold theory will be used to analyse the dynamics of the system near β = β∗. thus, e0 is a nonhyperbolic equilibrium, when β = β∗. now, the components of the right eigenvector w = (w1, w2, w3, w4, w5, w6) t of j∗ associated with the zero eigenvalue are given by w1 = −k1k2[µ(ν + µ)(ω + δ + µ) + δµ(1− η)ω] + ωδτ(ηµ+ ν)[α(µ+ ξ) + k2(µ+ ρ)] τδµk2(θ + ν + µ)(ω + µ) w4, w2 = −ωδµ[τ (k2(µ+ ρ) + α(µ+ ξ)) (2− η)− (1− η)] + θµ(δ + ω + µ) τδµk2(θ + ν + µ)(ω + µ) w4, w3 = α + ε+ µ+ ρ τδ w4, w4 = w4 > 0, w5 = α γ + µ+ ξ w4, w6 = (1− τ)(α + ε+ µ+ ρ)(γ + µ+ ξ) + ετ(γ + µ+ ξ) + γατ τ(ω + µ)(γ + µ+ ξ) w4. similarly, the components of the left eigenvector v = (v1, v2, v3, v4, v5, v6) t of j∗ associated with the zero eigenvalue are given by v1 = v2 = v6 = 0, v3 = v3 > 0, v4 = β∗s0(σ1(γ + µ+ ξ) + ασ3) (α + ε+ µ+ ρ)(γ + µ+ ξ) v3, v5 = β∗s0σ3 γ + µ+ ξ v3. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 69 since the first, second and six component of v are zero, we don’t need the partial derivatives of f1, f2 and f6. from the partial derivatives of f3, f4 and f5 at the disease free equilibrium point, the only ones that are nonzero are the following: ∂2f3 ∂x3∂x1 = ∂2f3 ∂x1∂x3 = β∗σ2, ∂2f3 ∂x4∂x1 = ∂2f3 ∂x1∂x4 = β∗σ1, ∂2f3 ∂x5∂x1 = ∂2f3 ∂x1∂x5 = β∗σ3, ∂2f3 ∂x3∂β = σ2s 0, ∂2f3 ∂x4∂β = σ1s 0, ∂2f3 ∂x5∂β = σ3s 0. the direction of the bifurcation at r0 = 1 is determined by the signs of the bifurcation coefficients a and b. hence, a = v3 6∑ i,j=1 wiwj ∂2f3 ∂xi∂xj (s0, p 0, 0, 0, 0, 0) = 2v3w1 (w3β ∗σ2 + w4β ∗σ1 + w5β ∗σ3) = 2β∗w1 ( σ2k1 τδ + σ1 + ασ3 k2 ) v3w4 =− 2(δ + µ) (τδ)2k2π(ν + µ)(ω + µ) [ k21k2 (µ(ν + µ)(ω + δ + µ) + δµ(1− η)ω) + ωδτk1(ηµ+ ν) (α(µ+ ξ) + k2(µ+ ρ))] v3w 2 4 < 0. and b = v3 6∑ i=1 wi ∂2f3 ∂xi∂β (s0, p 0, 0, 0, 0, 0) = v3 ( k1w4σ2s 0 τδ + w4σ1s 0 + αw4σ3s 0 k2 ) = (δ + µ)(α + ε+ µ+ ρ) β∗τδ v3w4 > 0. since a < 0 and b > 0 at β = β∗. based on the theorem 4.1 stated in castillo-chavez and song (2004), the system (2) undergoes a forward bifurcation at r0 = 1 and the unique endemic equilibrium e1 is locally asymptotically stable for r0 > 1. 3.8. bifurcation analysis we investigate the nature of the bifurcation by using the center manifold theory castillochavez and song (2004). in short, the theory is summarized by theorem 4.1 in castillochavez and song (2004). in such a theorem, there are two important quantities: the coefficients, say a and b, of the normal form representing the dynamics of the system on the central manifold. these coefficients decide the bifurcation. in particular, if a < 0 and b > 0, then the bifurcation is forward. in the proof of theorem (3.6), we have already justified the system (2) undergoes a forward bifurcation at r0 = 1. thus the basic reproduction number r0 plays an important role in the disease spread. if r0 < 1, then its easy to control the disease but if r0 > 1, then the society will experience endemic disease spreading. the forward bifurcation diagram can be seen in figure (2). east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 70 figure 2: forward bifurcation diagram for the covid-19 model (2). from figure (2), it is clear that when r0 < 1, the system (2) has no endemic equilibrium and the disease-free equilibrium is stable. when r0 > 1, a stable endemic equilibrium appears and the disease free equilibrium becomes unstable, i.e. exchange of stability of the equilibrium’s (forward bifurcation) occurs at the bifurcation point r∗ 0 = 1. 3.9. sensitivity analysis sensitivity analysis is a useful tool in model building as well as in model evaluation by showing how the model behavior responds to changes in parameter values martcheva (2015). the threshold parameter r0 which determines stability is a function of the parameters π, β, σ1, σ2, σ3, ν, µ, θ, δ, γ, ξ, α, ε, ρ, τ. we recall that the basic reproduction number r0 is given by r0 = πβ(ν + µ) [(γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα] µ(θ + ν + µ)(δ + µ)(α + ε+ µ+ ρ)(γ + µ+ ξ) . thus, in order to identify the most sensitive parameters for model (2), we compute the relative sensitivity of r0 with respect to the above parameters. then using the parameter values from table (3), we display the sensitivity indices of r0 with respect to the parameters in figure (3). east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 71 △r0 β = ∂r0 ∂β × β r0 = 1, △r0 π = ∂r0 ∂π × π r0 = 1, △r0 σ1 = ∂r0 ∂σ1 × σ1 r0 = σ1τδ(γ + µ+ ξ) (γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα , △r0 σ2 = ∂r0 ∂σ2 × σ2 r0 = σ2(α + ε+ µ+ ρ)(γ + µ+ ξ) (γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα , △r0 σ3 = ∂r0 ∂σ3 × σ3 r0 = σ3τδα (γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα , △r0 τ = ∂r0 ∂τ × τ r0 = τδ [σ1(γ + µ+ ξ) + σ3α] (γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα , △r0 ν = ∂r0 ∂ν × ν r0 = θν (θ + ν + µ)(ν + µ) , △r0 α = ∂r0 ∂α × α r0 = ατδ [σ3(ε+ µ+ ρ)− σ1(γ + µ+ ξ)] (α + ε+ µ+ ρ) [(γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα] , △r0 δ = ∂r0 ∂δ × δ r0 = δ [(γ + µ+ ξ) [σ1τµ− σ2(α + ε+ µ+ ρ)] + σ3ταµ] (δ + µ) [(γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα] , △r0 θ = ∂r0 ∂θ × θ r0 = − θ θ + ν + µ , △r0 ε = ∂r0 ∂ε × ε r0 = − ετδ [σ1(γ + µ+ ξ) + σ3α] (α + ε+ µ+ ρ) [(γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα] , △r0 ρ = ∂r0 ∂ρ × ρ r0 = − ρτδ [σ1(γ + µ+ ξ) + σ3α] (α + ε+ µ+ ρ) [(γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα] , △r0 γ = ∂r0 ∂γ × γ r0 = − σ3τδαγ (γ + µ+ ξ) [(γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα] , △r0 ξ = ∂r0 ∂ξ × ξ r0 = − σ3τδαξ (γ + µ+ ξ) [(γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα] , △r0 µ = ∂r0 ∂µ × µ r0 = 1 (ν + µ)d [ µd − [ σ2a(α + ε+ µ+ ρ)2(γ + µ+ ξ)2(ν + µ) + σ1τδ[(α + ε+ ρ)a+b](γ + µ+ ξ)2(ν + µ) + σ3τδα [(γ + ξ)(a+b) + (α + ε+ ρ)b + c] (ν + µ)]] , where a = δ(θ + ν) + 2µ(δ + θ + ν) + 3µ2, b = 2µδ(θ + ν) + 3µ2(δ + θ + ν) + 4µ3, c = 3µ2δ(θ + ν) + 4µ(δ + θ + ν) + 5µ4, d = (α + ε+ µ+ ρ)(γ + µ+ ξ)(δ + µ)(θ + ν + µ) [(γ + µ+ ξ) [σ2(α + ε+ µ+ ρ) + σ1τδ] + σ3τδα] . east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 72 note that the sensitivity index may depend on several parameters of the system, but also can be constant, independent of any parameter. for example, △r0 β = +1 means that increasing (decreasing) β by a given percentage increases (decreases) always r0 by that same percentage. figure 3: the sensitivity indices of r0 with respect to the parameters. figure (3) shows that the recruitment rate π, the contact rate β, the modification parameter σ2, the exposed progression rate δ, the natural death rate µ , the protection rate θ and the waning rate of protected individuals to susceptible class ν are the most sensitive parameters for r0. the parameters τ, σ1, σ2, σ3, ν, β and π have positive correlation with r0. this indicates that the spread of covid-19 decreases with decrease of these parameters. the parameters ξ, θ, ρ, µ, γ, ε, δ and α have negative correlation with r0. this implies that the spread of the virus decreases with an increase of these parameters. 4. numerical simulations and discussion in this section, we perform numerical simulation to support our analytical results. the numerical simulations are carried out with help of the ode45 matlab tool. using the parameter values given in table (3) and the initial conditions below in the model equations (2) simulation study is conducted. the parameter values have been taken based on the literature and the real characteristics of the virus. furthermore, initial conditions are determined as follow. the total population of ethiopia for the year 2021 is estimated about n(0) = 114, 963, 588 people kifle and obsu (2022). on december 31, 2020 the total active cases (infected individuals are 10,245 i.e i(0) = 10, 245), and the hospitalized are h(0) = 5062 and the total recovered by the date are r(0) = 81, 144 and we are assumed p (0) = 108076, e(0) = 15000 and hence is s(0) = n(0)− (p (0) + e(0) + i(0) +h(0) + r(0)) = 114, 744, 061. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 73 table 3: the parameter values of the modified model (per day). parameter value source π 1300 assumed θ 0.7 assumed ν 0.15 assumed β 0.00000058 assumed σ1 0.0001 alemneh and telahun (2020) σ2 0.02 alemneh and telahun (2020) σ3 0.00003 assumed δ 1/14 kifle and obsu (2022) α 0.04 assumed µ 1/(64*12*30)kifle and obsu (2022) ρ 0.0004 alemneh and telahun (2020) ξ 0.015 assumed τ 0.7 alemneh and telahun (2020) ε 0.0476 assumed γ 0.033 assumed η 0.4 assumed ω 0.011 assumed east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 74 figure (4) shows the predicted total confirmed cases and the real data total confirmed cases for ethiopia from 31 december 2020 to 30 march 2022 (it the data has been taken covid-19 pandemic (2022) ). there is some differences between the prediction and the real data that should come due to the fact that there were no enough covid test kits during the early time not only in ethiopia but also all over the world. after wards we continue to validate the local stability of dfe and eep of model. figure 4: the prediction using model (2) and the real data of confirmed cases for ethiopia from 31 december 2020 to 30 march 2022 in figure (5) with r0 = 0.22950, we observe that for the basic reproduction number r0 < 1, all solutions curve goes to the disease free equilibrium point. as a result, the disease goes to extinct or the disease dies out. in figure (6) with r0 = 1.10791, we observe that for the basic reproduction number r0 > 1, all solutions curve goes away from the disease free equilibrium point. these indicate that the disease-free equilibrium point is unstable for the values of r0 > 1, and the solutions will go to the endemic equilibrium point. consequently, the disease invade in a population. in figure (7), we observe as the protection rate θ increases, all infected classes will significantly decrease over time. this confirmed the result from the fact that strict use of safety (protection) measures within the population plays a critical role in confine the spread of the disease as in bachar et al. (2021). it is predicted that the population will be disease-free. this is due to the case that when protection rate increases the basic reproduction number decreases. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 75 figure 5: the time series plot of model (2) when r0 = 0.22950 in figure (8), we observe that as the contact rate β decrease, r0 and also all infected classes are decreasing. further this habitual the result obtained from the fact that a decrease in contact among the population plays a indispensable role in curtailing the spread of the disease as in ahmed et al. (2021). 5. extension of the modified model into an optimal control in this section, we will use optimal control theory to find protection (for susceptible) and hospitalization (for infected) strategies that would mitigate the spread of covid19 in the population. 5.1. optimal protection and hospitalization using modified model in this subsection, we study the optimal protection of susceptible population and hospitalization of infected individuals in order to minimize the outbreak of covid-19 in the population. let us define our control set u to be u = {(θ(t), α(t)) : 0 ≤ θ(t), α(t) ≤ ϵi, 0 ≤ t ≤ t, 0 < ϵi ≤ 1, i = 1, 2}, (9) where θ(t) and α(t) are lebesgue measurable quantities bounded above by ϵ1 and ϵ2 respectively. we will minimize the objective functional j [θ(t), α(t)] = ∫ t 0 ( b1e(t) +b2i(t) + 1 2 ( a1θ 2(t) +a2α 2(t) )) dt, (10) where constants b1, b2, a1 and a2 are positive. here, we want to find the optimal values θ(t) and α(t) that minimizes the objective functional (10) subject to the state system (2). the goal is to find the optimal control (θ∗(t), α∗(t)) such that j [θ∗(t), α∗(t)] = min (θ,α)∈u j [θ(t), α(t)]. (11) east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 76 figure 6: the time series plot of model (2) when β = 0.0000028 with r0 = 1.11073 figure 7: impact of protection rate θ on r0 and infected classes. 5.2. existence of an optimal control the existence of the optimal control can be showed by using an approach of fleming and east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 77 figure 8: impact of contact rate β on r0 and infected classes. rishel (2012). theorem 5.1. given the objective functional j(θ(t), α(t)) (10) with admissible control set u , subject to the state system (2), then there exist an optimal control double u∗ = (θ∗, α∗) in u such that j [θ∗, α∗] = min (θ,α)∈u j [θ(t), α(t)]. (12) proof. to prove the existence of optimal control, we need to verify the following conditions. (a) the set of solutions to the state system (2) and control parameters in (9) are non-empty. (b) the set u is convex and closed. (c) the right hand side of system (2) is bounded above by sum of bounded control and state and can be written as a linear function of the control variables with coefficients dependent on time and state variables. (d) the integrand function l(e, i, θ, α, t) is convex on u and l(e, i, θ, α, t) ≥ h(u), where h(u) is continuous and ||u||−1h(u) → ∞ when ||u|| → ∞. here u = (θ(t), α(t)). in theorem (3.2), we have already justified the boundedness of the solution of the state system (2). since our solution for the model is bounded by n(t) ≤ max ( n(0), π µ ) for all t ≥ 0. this implies that the solutions of the state system are continuous and bounded for each admissible control functions in u . moreover, the right hand side of the model equations (2) satisfes the lipschitz condition with respect to state variables. hence, the state system (2) has a unique solution corresponding to each admissible control function (θ(t), α(t)) ∈ u . thus, condition (a) is achieved. to verify condition (b), given that the control set u = {u ∈ r2 : ||u||∞ ≤ 1}. let ψ ∈ [0, 1] and v1, v2 ∈ u such that ||v1||∞ ≤ 1 and ||v2||∞ ≤ 1, then ||ψv1+(1−ψ)v2||∞ ≤ ψ||v1||∞+(1−ψ)||v2||∞ ≤ 1. thus, the set u is convex and closed. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 78 to verify condition (c), let u = (θ(t), α(t)) ∈ u, x = (s, p,e, i,h,r) and the right hand side of the state system (2) is given by f(t,x, u) =  π+ ηωr + νp − β(σ1i + σ2e + σ3h)s − (θ(t) + µ)s θ(t)s + (1− η)ωr− (ν + µ)p β(σ1i + σ2e + σ3h)s − (δ + µ)e τδe − (α(t) + ε+ µ+ ρ)i α(t)i − (γ + µ+ ξ)h (1− τ)δe + εi + γh − (ω + µ)r  . (13) then from (13) we get, f(t,x, u) = g(t,x) + h(t,x)ut , where g(t,x) =  π+ ηωr + νp − β(σ1i + σ2e + σ3h)s − µs (1− η)ωr− (ν + µ)p β(σ1i + σ2e + σ3h)s − (δ + µ)e τδe − (ε+ µ+ ρ)i −(γ + µ+ ξ)h (1− τ)δe + εi + γh − (ω + µ)r  and h(t,x) =  −s 0 s 0 0 0 0 −i 0 i 0 0  . since, by using the properties of a norm of a matrix we have, ||f(t,x, u)|| = ||g(t,x) + h(t,x)ut || ≤ ||g(t,x)||+ ||h(t,x)|| ||u||. thus, condition (c) is proved. to verify condition (d), the integrand of the objective functional (10) l(e, i, θ, α, t) = b1e(t) +b2i(t) + 1 2 ( a1θ 2(t) + a2α 2(t) ) (14) is the sum of convex function and hence convex with respect to control parameters θ(t) and α(t). moreover, l(e, i, θ, α, t) = b1e(t) +b2i(t) + 1 2 ( a1θ 2(t) + a2α 2(t) ) ≥ 1 2 ( a1θ 2(t) + a2α 2(t) ) . we define a continuous function h(u) = ϕ||u||2, where ϕ = min ( a1 2 , a2 2 ) > 0 and u = (θ(t), α(t)). then we have l(e, i, θ, α, t) ≥ 1 2 ( a1θ 2(t) +a2α 2(t) ) ≥ ϕ||u||2, (15) since ϕ = min ( a1 2 , a2 2 ) > 0. this implies that l(e, i, θ, α, t) ≥ h(u). consider, ||u||−1h(u) = ||u||−1ϕ||u||2 = ϕ||u||. this gives that ||u||−1h(u) = ϕ||u|| → ∞ when ||u|| → ∞. thus, condition (d) is proved. hence, all conditions (a)-(d) shows that there exists an optimal control u∗ = (θ∗, α∗) that minimizes the cost functional j(θ(t), α(t)) over u . therefore, the existence of optimal control is established. 5.3. the hamiltonian and optimality system we used pontryangin’s maximum principle lenhart and workman (2007) to drive the necessary conditions that an optimal control must satisfy. this principle converts the objective functional (10) subject to the state system (2) into a problem of minimizing point-wise a hamiltonian (h), with respect to θ(t) and α(t) as: east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 79 h = b1e +b2i + 1 2 a1θ 2 + 1 2 a2α 2 + λ1[π + ηωr + νp − β(σ2e + σ1i + σ3h)s − (θ + µ)s] + λ2[θs + (1− η)ωr− (ν + µ)p ] + λ3[β(σ2e + σ1i + σ3h)s − (δ + µ)e] + λ4[τδe − (α + ε+ µ+ ρ)i] + λ5[αi − (γ + µ+ ξ)h] + λ6[(1− τ)δe + εi + γh − (ω + µ)r], (16) where λi, i = 1, 2, 3, 4, 5, 6, represent the adjoint variables associated with the state variables s, p,e, i,h and r to be determined suitably by applying pontryagin’s maximal principle lenhart and workman (2007). theorem 5.2. for an optimal control set θ, α that minimizes j over u , there are adjoint variables, λ1, ..., λ6 such that: dλ1 dt = [β(σ2e + σ1i + σ3h) + θ + µ]λ1 − θλ2 − β(σ2e + σ1i + σ3h)λ3, dλ2 dt = −νλ1 + (ν + µ)λ2, dλ3 dt = −b1 + βσ2sλ1 − [βσ2s − (δ + µ)]λ3 − τδλ4 − (1− τ)δλ6, dλ4 dt = −b2 + βσ1sλ1 − βσ1sλ3 + (α + ε+ µ+ ρ)λ4 − αλ5 − ελ6, dλ5 dt = βσ3sλ1 − βσ3sλ3 + (γ + µ+ ξ)λ5 − γλ6, dλ6 dt = −ηωλ1 − (1− η)ωλ2 + (ω + µ)λ6. (17) with transiversality conditions λi(t ) = 0, i = 1, ..., 6. (18) moreover, we obtain the control set (θ∗, α∗) characterized by θ∗(t) = max { 0,min ( ϵ1, s(λ1 − λ2) a1 )} , α∗(t) = max { 0,min ( ϵ2, i(λ4 − λ5) a2 )} . (19) proof. the form of the adjoint equations and transversality conditions are standard results from pontryagin’s maximum principle lenhart and workman (2007). we differentiate hamiltonian (h) (16) with respect to the state variables s, p,e, i,h and r, respectively, and then the adjoint east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 80 system can be written as dλ1 dt = −∂h ∂s = [β(σ2e + σ1i + σ3h) + θ + µ]λ1 − θλ2 − β(σ2e + σ1i + σ3h)λ3, dλ2 dt = −∂h ∂p = −νλ1 + (ν + µ)λ2, dλ3 dt = −∂h ∂e = −b1 + βσ2sλ1 − [βσ2s − (δ + µ)]λ3 − τδλ4 − (1− τ)δλ6, dλ4 dt = −∂h ∂i = −b2 + βσ1sλ1 − βσ1sλ3 + (α + ε+ µ+ ρ)λ4 − αλ5 − ελ6, dλ5 dt = −∂h ∂h = βσ3sλ1 − βσ3sλ3 + (γ + µ+ ξ)λ5 − γλ6, dλ6 dt = −∂h ∂r = −ηωλ1 − (1− η)ωλ2 + (ω + µ)λ6. with transversality conditions λi(t ) = 0, i = 1, ..., 6. similarly by following the approach of pontryagin et al pontryagin (2018), the characterization of optimal controls θ∗(t), α∗(t), that is, the optimality equations are obtained based on the conditions: ∂h ∂θ = 0 and ∂h ∂α = 0, which gives, θ = s(λ1 − λ2) a1 , α = i(λ4 − λ5) a2 . since θ and α are bounded in u by ϵ1 and ϵ2 respectively. therefore, the optimal controls θ∗(t) and α∗(t) are given by θ∗(t) = max { 0,min ( ϵ1, s(λ1 − λ2) a1 )} , α∗(t) = max { 0,min ( ϵ2, i(λ4 − λ5) a2 )} . this completes the proof. the optimality system is formed from the state system (2) and the adjoint variable system (17) by incorporating the characterized control set and initial and transversal condition. then we have the following optimality system: east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 81 ds dt = π+ ηωr + νp − β(σ1i + σ2e + σ3h)s − (θ∗ + µ)s, dp dt = θ∗s + (1− η)ωr− (ν + µ)p, de dt = β(σ1i + σ2e + σ3h)s − (δ + µ)e, di dt = τδe − (α∗ + ε+ µ+ ρ)i, dh dt = α∗i − (γ + µ+ ξ)h, dr dt = (1− τ)δe + εi + γh − (ω + µ)r, dλ1 dt = [β(σ2e + σ1i + σ3h) + θ∗ + µ]λ1 − θ∗λ2 − β(σ2e + σ1i + σ3h)λ3, dλ2 dt = −νλ1 + (ν + µ)λ2, dλ3 dt = −b1 + βσ2sλ1 − [βσ2s − (δ + µ)]λ3 − τδλ4 − (1− τ)δλ6, dλ4 dt = −b2 + βσ1sλ1 − βσ1sλ3 + (α∗ + ε+ µ+ ρ)λ4 − α∗λ5 − ελ6, dλ5 dt = βσ3sλ1 − βσ3sλ3 + (γ + µ+ ξ)λ5 − γλ6, dλ6 dt = −ηωλ1 − (1− η)ωλ2 + (ω + µ)λ6, λi(t ) = 0, i = 1, ..., 6, (s(0), p (0), e(0), i(0), h(0), r(0)) = (s0, p0, e0, i0, h0, r0) . 6. numerical simulations of optimal control problem in this section, we perform some numerical solutions on the modified model (2) and the resulting optimality system consisting of the state equations (2) and the adjoint system (17) with the characterizations (19). we make use of the parameter values given in table (3) for the simulation. an iterative scheme is used to find the optimal solution of the optimality system. since the state system (2) has initial conditions and the adjoint systems (17) have final conditions, we solve the state system using a forward fourth-order runge–kutta method and solve the adjoint system using a backward fourthorder runge–kutta method ?. the solution iterative scheme involves making a guess of the controls and using that guess to solve the state system. the initial guess of the control together with the solution of the state systems is used to solve the adjoint systems. the controls are then updated using a convex combination of the previous controls and the values obtained using the characterizations. the updated controls are then used to repeat the solution of the state and adjoint systems. this process is repeated until the values in the current iteration are close enough to the previous iteration values lenhart and workman (2007). we used b1 = b2 = 1, a1 = 40, a2 = 80 and final intervention time t = 350 days for simulation of covid-19 model with optimal control. additionally, we used s(0) = 110079, p (0) = 108076, e(0) = 15000, i(0) = 13813, h(0) = 10050, r(0) = 12156 as initial values. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 82 6.1. optimal control comparisons and strategies in this subsection, we compare the results of constant and optimal control as did in ?. we first compare the cost of infection for each strategies and then compare the exposed and infected population. the optimal control cost for each parameter is less than the constant control at all times as depicted in figures (91) and (101). it can be observed that for protection rate θ the cost reduction is significant compared to the other parameters which is due to the high sensitivity of parameter over the system. 0 50 100 150 200 250 300 350 time in days 2 4 6 8 10 12 14 16 co st of di se as e c on tro l #104 optimal control 3=0.01 3=0.24 3=0.47 3=0.7 (1) 0 50 100 150 200 250 300 350 time in days 0 2 4 6 8 10 12 14 ex po se d p op ula tio n #104 optimal control 3=0.01 3=0.24 3=0.47 3=0.7 (2) 0 50 100 150 200 250 300 350 time in days 1 2 3 4 5 6 7 inf ec ted p op ula tio n #104 optimal control 3=0.01 3=0.24 3=0.47 3=0.7 (3) 0 50 100 150 200 250 300 350 time in days 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 pr op or tio n o f p op ula tio n p ro tec ted -= 0.0001 -=0.00015 -= 0.0002 -=0.00025 (d) figure 9: optimal control for θ. (a) cost comparison for optimal and constant controls for θ. (b) exposed population comparison for optimal and constant controls for θ. (c) infected population comparison for optimal and constant controls for θ. (d) optimal strategies for θ with different β. now we compare the exposed population using constant and optimal controls. in figure (92), we observe that the optimal time dependent protection strategy, θ, yields a significant drop in exposed population when compared to its constant counterparts, similarly using the optimal time dependent hospitalization strategy α we see a significant drop in the exposed population as compared to constant rates of hospitalization over time as depicted in figure (102). we compare the infected population using constant and optimal controls. in figure (93), we observe that the optimal time dependent protection strategy, θ, yields a significant drop in infected population when compared to its constant counterparts, similarly using the optimal time dependent hospitalization strategy α we see a significant drop in the infected population as compared to constant rates of hospitalization over time as depicted in figure (103). as contact rate β increases, so does the time for which the maximum control should be applied. in figures (9d) and (10d), we obeast afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 83 0 50 100 150 200 250 300 350 time in days 2 3 4 5 6 7 8 9 10 co st of di se as e c on tro l #104 optimal control ,=0.1 ,=0.16667 ,=0.23333 ,=0.3 (1) 0 50 100 150 200 250 300 350 time in days 1 2 3 4 5 6 7 ex po se d p op ula tio n #104 optimal control ,=0.1 ,=0.16667 ,=0.23333 ,=0.3 (2) 0 50 100 150 200 250 300 350 time in days 0 0.5 1 1.5 2 2.5 3 inf ec ted p op ula tio n #104 optimal control ,=0.1 ,=0.16667 ,=0.23333 ,=0.3 (3) 0 50 100 150 200 250 300 350 time in days 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 pr op or tio n o f p op ula tio n h os pit ali ze d -= 0.0001 -=0.00015 -= 0.0002 -=0.00025 (d) figure 10: optimal control for α. (a) cost comparison for optimal and constant controls for α. (b) exposed population comparison for optimal and constant controls for α. (c) infected population comparison for optimal and constant controls for α. (d) optimal strategies for α with different β. serve that for both protection and hospitalization the maximum possible protection and hospitalization rates should be maintained to the first few days of the disease which can then be reduced over time. finally, from figures (112) and (113), one can easily conclude that the combination of the two controls is significantly more effective in reducing the spread of the virus than when each control is singly applied. hence, the best choice is to apply two controls all together to mitigate the spread of covid-19 in the population. from figure (111), one can observe that the combined implementation of the two control measures is the most cost-effective when compared with the single implementation of each control measure. 7. conclusion in this paper, we proposed a deterministic compartmental model to study the transmission dynamics of covid-19. the model was an extension of the existing seir model by including protected and hospitalized individuals. we established the well-posedness of the modified model by proving the existence, positivity, and boundedness of the solutions. we computed the steady states and the basic reproduction number r0. based on the reproduction number r0, it is revealed that whenever r0 < 1, the system has only disease free equilibrium e0 which is locally as well as globally asymptotically stable. when r0 > 1, the system has a unique endemic equilibrium e1 which is locally stable and the disease free equilibrium e0 becomes unstable. we have observed that the outbreak of the disease dies out if r0 < 1 and the disease is endemic if r0 > 1. using center manifold theory, bifurcation analysis of the modified model was proven and the model exhibits forward bifurcation at r0 = 1. in addition from sensitivity analysis of r0, we observed that the recruitment rate π and east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 84 0 50 100 150 200 250 300 350 time in days 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 co st of di se as e c on tro l #104 both optimal only , optimal only 3 optimal (1) 0 50 100 150 200 250 300 350 time in days 1 2 3 4 5 6 7 ex po se d p op ula tio n #104 both optimal only , optimal only 3 optimal (2) 0 50 100 150 200 250 300 350 time in days 0 0.5 1 1.5 2 2.5 3 3.5 inf ec ted p op ula tio n #104 both optimal only , optimal only 3 optimal (3) figure 11: optimal control for θ, α and both. (a) cost comparison for optimal θ, α (b) exposedand both. population comparison. (c) infected population comparison. references ahmed i., modu g. u., yusuf a., kumam p. and yusuf i. (2021), ‘a mathematical model of coronavirus disease (covid-19) containing asymptomatic and symptomatic classes’, results in physics 21, 103776. alemneh h. t. and telahun g. t. (2020), ‘mathematical modeling and optimal control analysis of covid-19 in ethiopia’, medrxiv . allen l., brauer f., van den driessche p. and wu, j. (2008), ‘mathematical epidemiology, volume 1945 of lecture notes in mathematics’, springer, berlin 13, 14. bachar m., khamsi m. a. and bounkhel m. (2021), ‘a mathematical model for the spread of covid-19 and control mechanisms in saudi arabia’, advances in difference equations 2021(1), 1–18. brauer f., castillo-chavez c. and feng z. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 85 contact rate β are most sensitive parameters to our model. numerical results support the fact that decrease in the contact rate β causes the decrease in the value of r0 and after a certain level of β, r0 become less than one. if the protection rate increases, then all infected classes are decrease. it is predicted that the population will be disease-free. furthermore, using optimal control theory we suggest protection and hospitalization strategies. pontryagin’s maximum principle is used to establish the existence and characterization of optimal controls. the study demonstrates that the combined application of both controls is much more effective in reducing the spread of the virus than when each control is applied individually. finally, our analysis indicates that an optimal control is more preferable than maintaining a high constant control. (2019), mathematical models in epidemiology, vol. 32, springer. castillo-chavez c. blower, s. van den driessche p., kirschner d. and yakubu a.-a. (2002), mathematical approaches for emerging and reemerging infectious diseases: models, methods, and theory, vol. 126, springer science & business media. castillo-chavez c. and song b. (2004), ‘dynamical models of tuberculosis and their applications’, mathematical biosciences & engineering 1(2), 361. covid-19 pandemic (2022), ‘covid-19 pandemic in ethiopia — wikipedia, the free encyclopedia’. diekmann o., heesterbeek j. and roberts m. g. (2010), ‘the construction of nextgeneration matrices for compartmental epidemic models’, journal of the royal society interface 7(47), 873–885. fleming w. h. and rishel r. w. (2012), deterministic and stochastic optimal control, vol. 1, springer science & business media. gurmu e. d., batu, g. b. and wameko, m. s. (2020), ‘mathematical model of novel covid-19 and its transmission dynamics’, international journal of mathematical modelling & computations 10(2 (spring)), 141–159. kifle z. s. and obsu, l. l. (2022), ‘mathematical modeling for covid-19 transmission dynamics: a case study in ethiopia’, results in physics p. 105191. lemecha obsu l. and feyissa balcha s. (2020), ‘optimal control strategies for the transmission risk of covid-19’, journal of biological dynamics 14(1), 590–607. lenhart s. and workman j. t. (2007), optimal control applied to biological models, crc press. martcheva m. (2015), an introduction to mathematical epidemiology, vol. 61, springer. pontryagin l. s. (2018), mathematical theory of optimal processes, routledge. sohrabi c., alsafi z., o’neill n., khan,m., kerwan a., al-jabir a., iosifidis c. and agha r. (2020), ‘world health organization declares global emergency: a review of the 2019 novel coronavirus (covid-19)’, international journal of surgery 76, 71– 76. toquero c. m. (2020), ‘challenges and opportunities for higher education amid the covid-19 pandemic: the philippine context.’, pedagogical research 5(4). valcher m. e. (2002), ‘positive systems in the behavioral approach: main issues and recent results’, electronic proceedings of mtns 2002. yang c. and wang j. (2020), ‘a mathematical model for the novel coronavirus epidemic in wuhan, china’, mathematical biosciences and engineering: mbe 17(3), 2708. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 58-86 86 eajbcs__volume_5_issue 2_ article 5_ tinaw and kiros_ a mathematical model for the transmission dynamics of covid 19 pandemic.pdf (p.64-92) introduction mathematical model formulation the modified mathematical model model formulation qualitative analysis of the modified model well-posedness steady state basic reproduction number local stability of disease free equilibrium global stability of disease free equilibrium endemic equilibrium point local stability of endemic equilibrium bifurcation analysis sensitivity analysis numerical simulations and discussion extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion east east afr. j. biophys. comput. sci. (2025), vol. 6, issue. 1, 1-14 *corresponding author: email: joseph.saria@gmail.com , +255-719936151 https://dx.doi.org/10.4314/eajbcs.v6i1.1s influence of vat leach reprocessed tailings on heavy metals levels around sekenke gold mine, iramba district, tanzania romanus priscus *1 and josephat saria2 1geological survey of tanzania, p. o. box 903, dodoma, tanzania 2dept. of physical and environmental sciences the open university of tanzania, p. o. box 23409, dar es salaam, tanzania, keywords: heavy metals; geoaccumulation index (igeo); contamination factor (cf); pollution load index (pli); iramba abstract soil pollution is a worldwide phenomenon which results from both natural and anthropogenic activities. this has resulted in several health and physiological problems in both plants and human. this study investigated the concentration of heavy metal contaminants at senkenke gold mining areas in nine tailings samples before processing and in nine tailing samples after processing using xrf rigaku nex cg and arsenic was determined using aas equipped with a continuous flow of vga. arsenic mean concentration in unprocessed samples was 32.873 ± 26.284 mg/kg, while in processed tailings was 24.390 ± 19.394 mg/kg. the mean concentration of pb in unprocessed tailing was 44.012 ± 37.091mg/kg, while in processed tailing was 38.402 ± 28.270 mg/kg. the mean concentration of cd in unprocessed tailing was 4.513 ± 1.022 mg/kg, while in processed tailing was 3.089 ± 1.329 mg/kg. chromium mean concentration in unprocessed tailing was 194.526± 22.670 mg/kg while in processed tailing was 141.352 ± 30.726 mg/kg. the igeo values found in the following increasing order in unprocessed tailing zn < fe < pb < cr < as < cd while in processed tailing was in the following increasing order zn < fe < cr < as < pb < cd. the pli values calculated for tailing samples are found to 4.423 for unprocessed tailing and 2.807 for processed tailing which shows that the soils are polluted and the environment is deteriorated in their quality. the findings revealed that the soils and mine tailings in the study area were polluted with heavy metals, particularly as, pb and cr and mostly cd. the heavy metal concentrations decrease from unprocessed tailing to processed tailings. this pollution poses significant environmental and health risks. . introduction mining is a crucial driver of global economic growth, with the extraction of precious metals serving as a significant source of foreign exchange for many developing nations. tanzania, rich in minerals and natural resources such as gold, diamonds, coal and natural gas, generated around 3.6 billion u.s. dollars from mineral exports. this was a rise from 2.3 billion u.s. dollars in 2023 (cowling, 2024). gold was the largest contributor to the country's mineral export earnings. the extraction and processing of precious metals often come with considerable environmental and public health risks. for example, mine tailings east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx research article mailto:joseph.saria@gmail.com https://dx.doi.org/10.4314/eajbcs.v6i1.1s east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 1-14 2 from gold ore processing can pollute the environment (roussel et al., 2000). these tailings commonly contain heavy metals and leftover reagents such as cyanide. several researchers (raji et al., 2021, shapi et al., 2021) have documented high concentrations of heavy metals in water streams near gold mines, while miller (2022) indicated heavy metals from mining activities can remain in surface soil layers for many years. tailings are a mix of finely ground rock residues left after valuable minerals have been extracted, combined with the water used in processing. in countries with limited environmental regulation enforcement, large volumes of open-dumped tailings are common (baker and banfield, 2003). the chemical and physical makeup of tailings resembles that of typical river sand and silt, shaped by factors such as ore type, geochemistry, extraction methods, particle size, and specific chemical treatments used in processing (davies and rice, 2001; franks et al., 2011). gold mine tailings, in particular, have poor physical qualities, including low aggregation, high hydraulic conductivity, fine texture, and weak cohesion (khan et al., 2023). these characteristics set tailings apart from natural soil (vega et al., 2004; blight and fourie, 2005), with low cohesion contributing to fluctuations in moisture content and temperature within this hazardous waste. gold extraction generates a substantial amount of tailings, which are waste materials discarded after ore processing. these tailings often contain various contaminants, including mercury, arsenic, antimony, cyanide, and residuals (uddin et al., 2021). the process of mining gold can release numerous toxic pollutants, which pose health risks even at low concentrations. according to olise et al. (2019), artisanal gold mining is a well-known source of toxic metals in soil, sediment, and water, releasing harmful substances such as cadmium, arsenic, copper, lead, iron, chromium, nickel, and zinc into the environment. zinc and iron are among the most abundant element on earth (quintero-gutiérrez et al., 2008) and is a biologically essential component of every living organism (aisen et al., 2001). arsenic (as), a naturally occurring and abundant element in the earth's crust both organic and inorganic forms can be found in soil, with the latter being a very toxic form (shrivastava et al., 2015). arsenic can be due to smelting of gold, mining processes like smelting pharmaceutical waste, wastewater in mining site or combustion of fossil fuels (bhardwaj et al., 2020; biamontrojas et al., 2023). cadmium is frequently used in production of polyvinylchloride (pvc) products, alloys, pigments and batteries (wilson, 1988; yuan et al., 2019). chromium can be found in metal plating and paints, and pigments, rubber, photography, tanning and mining and metallurgy/metal purification (sharma et al., 2021). lead combustion of fossil fuels, paints and pigments; application of lead in gasoline, and solid waste, explosives, ceramics and dishware, solid waste combustion, paints and pigments, industrial dust and fumes, manufacturing of leadacid batteries, pesticides, mining and metallurgy, some types of pvc, urban runoff (obeng-gyasi, 2019). even though long-term exposure to heavy metals is linked to serious health problems like cancer, the public remains largely unaware of the associated risks. this contamination can harm human health through both direct and indirect exposure to these toxic metals (muradoglu et al., 2015; jin et al., 2019; liu et al., 2020). according to clancy et al. 2012, several acute https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/fossil-fuel https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/photosynthetic-pigment https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/solid-waste https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/urban-runoff east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 1-14 3 and chronic toxic effects of heavy metals affect different body organs. gastrointestinal and kidney dysfunction, nervous system disorders, skin lesions, vascular damage, immune system dysfunction, birth defects, and cancer are examples of the complications of heavy metals toxic effects. vat leaching is a process that involves using chemicals, such as cyanide or sulfuric acid, to extract gold from ore. when the leftover material, known as tailings, is reprocessed, these chemicals as well as heavy metals like arsenic, mercury, lead, and cadmium, which are often present in the ore can seep into nearby soil and water systems. consequently, evaluating the impact of these tailings on heavy metal levels is essential for assessing potential contamination of local ecosystems. to address this knowledge gap, this study aims to determine levels of heavy metals in tailings before processing and compare them with levels that remain after processing. specifically, this study will utilize xrd to analyze samples from senkenke mining areas, to determine the concentrations of heavy metals and assess pollution load through statistical analysis. materials and methods study area the study was conducted at the sekenke smallscale gold mine in iramba district, tanzania. located on a low rise in the wembere depression at 03°57′s and 34°15′e, gold was discovered here before 1914, leading to significant development, making it the largest reef-gold producer in the country. the mine spans approximately 252 hectares and includes 9 unprocessed tailings heaps, each containing around 5,000 tons of soil material. additionally, there are 9 reprocessed tailings heaps, totaling about 12,000 tons, situated around various processing plants. soil sample collection one sample from each tail was taken by opening small trenches/holes with a spade and using chisels for sampling. the collected 18 tailing samples were stored in teflon bags, tightened separately and taken to the geological survey of tanzania (gst) laboratory for analysis. in the laboratory samples were air-dried under a controlled environment to achieve constant weight. sample preparation the samples were dried at 50-105ºc for 24 hours to remove the moisture. the samples were grounded and then sieved to remove coarse debris and rubble with a size greater than 2.0mm. a non-metallic sieve was used to avoid contamination of metals. each sample was divided into three different potions (triplicate). from sample 1g of fine soil sample undergoes aqua regia digestion (hcl/hno3: 3/1) to attack a wide range of soil and geological materials, heated slowly near dryness. after the process of digestion, 20ml of distilled water was added to each sample, filtered and kept in a 100 ml volumetric flask, which was then diluted to the mark. the sample solutions were stored well in teflon bottles and analyzed by xrd instrument. the xrd operates by measuring the characteristic secondary radiation emitted from a sample that has been excited with an x-ray source. it is rapid, reliable, non-destructive and often quicker than other analysis techniques (karathanasis and hajek, 1996). to maintain the accuracy of the machine, three blank samples of silica sand collected from the coastal region east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 1-14 4 were prepared following all protocols of collected soil samples from the mine site and then analysed simultaneously with the soil samples. evaluation of heavy metal pollution the degree of contamination was analyzed by three indices for environmental assessment of soil in small scale mining of sekenke singida municipality. the indices are geo-accumulation index (igeo) and contamination factor (cf). geoaccumulation index (igeo) the igeo is a pollution degree evaluation index proposed by müller (1979) and is widely used to evaluate the pollution degree of single metal in water, ocean, and soil environments (banu et al., 2013). the calculation formula can be expressed as follows: igeo = log2         i i b c 5.1 (1) where ci represents the concentration of heavy metals measured in the soil (mg/kg), and bi refers to the geochemical background values based on the average composition of shales as proposed by turekian and wedepohl (1961). these shale values were chosen for calculating pollution indices as they allow for meaningful comparisons across different regions, aiding in the understanding of global trends in element enrichment and contamination (turekian and wedepohl, 1961; ali et al., 2016). shale values offer a consistent, standardized reference point and are relatively stable, minimizing significant variations in elemental composition over time.the background values adopted from edori and kpee (2017) where: as= 13; fe = 47,200; cr = 90; pb = 20; cd = 0.3 and zn = 95 both in mg/kg. förstner et al. (1993) listed geo-accumulation classes and the corresponding contamination intensity for different indices table 1. table 1: geo-accumulation index classification soil igeo contamination igeo accumulation class intensity index igeo >5 6 very strong >4 5 5 strong to very strong >3 4 4 strong >2 -3 3 moderate to strong >1 2 2 moderate >0 1 1 uncontaminated to moderate <0 0 practically uncontaminated contamination factor contamination factor ( fc ) was determined using single pollution index model. this is a basic and useful tool for detecting toxic metal contamination. this cf used to evaluate the individual toxic metal contamination in the soil. the standard employed for the interpretation of the contamination factor values was adopted from edori and kpee (2017) as given in eq. (2): = b m c c (2) where: cf = contamination factor; = cm = the concentration of the metal and cb = the background value. east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 1-14 5 hakanson, (1980) suggested four categories of cf to assess the metal contamination levels as when cf < 1: indicates low contamination (or no contamination). the concentration of the contaminant is less than the background level. when 1 ≤ cf < 3 indicates moderate contamination while 3 ≤ cf < 6 indicates considerable contamination and cf ≥ 6: indicates very high contamination. hakanson, (1980) proposed the contamination degree (cdeg) of the soil and was computed based on the sum of all contamination factors using the formula (equation 3) degc   n i cf 1 (3) where n is the number of analyzed metals. thecontamination degree of soil is divided into four groups: low (cdeg < 8), moderate (8 ≤ cdeg < 16), considerable (16 ≤ cdeg<32) and very high contamination degree (cdeg ≥ 32). a modified form of the contamination degree equation for the calculation of the overall degree of contamination was presented by abrahim and parker (2008). the modified degree of contamination cdeg, m) was calculated by the sum of all contamination factor (cf) for a given set of soil pollutants divided by the number of analyzed pollutants. this was calculated by the following formula (equation 4).    n i f m n c c 1 deg, (4) the classifications of the modified degree of contamination (cdeg,m) in soil are as follows: cdeg,m < 15, very low degree of contamination; 15 < cdeg,m < 2, low degree of contamination; 2 < cdeg, m < 4, moderate degree of contamination; 4 < cdeg,m < 8, high degree of contamination; 8 < cdeg,m < 16, very high degree of contamination; 16 <cdeg,m < 32, extremely high degree of contamination; cdeg,m > 32, ultra high degree of contamination spatial. table 2: classification of different pollution indices geoi valuea description cf valueb description pli valuec description igeo < 0 practically uncontaminated cf < 1 low contamination pli = 0 excellent 0< igeo <1 uncontaminated to moderate contaminated 1≤ cf < 2 low to moderate contamination pli = 1 baseline level of pollutants 1< igeo <2 moderate contaminated 2≤ cf < 3 moderate contamination pli > 1 polluted 2< igeo <3 moderate to heavily contaminated 3≤ cf < 4 moderate to high contamination 3< igeo <4 heavily contaminated 4≤ cf < 5 high contamination 4< igeo <5 heavily to extremely contaminated 5≤ cf < 6 high to very high contamination 5< igeo extremely contaminated cf ≥ 6 extreme contamination amuller (1969), b ma et al. (2022), cmkude et al. (2021) east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 1-14 6 the pollution load index (pli) the pollution load index (pli) is obtained as concentration factors (cf). this cf is the quotient obtained by dividing the concentration of each metal. the pli of the place are calculated by obtaining the n-root from the n-cf that was obtained for all the metals. with the pli obtained from sampling site. generally pollution load index (pli) as developed by lacatusu (2000) which is as follows (equation5): pli = ( 1fc × 2fc × 3fc × … fnc ) n/1 (5) where: pli is pollution load index, cf contamination factor of respective metal, n = number of metals. table 2 shows different classifications into which the contamination factor (cf), geo accumulation index (igeo) and pollution load index (pli) are categorized. statistical analysis a comprehensive statistical analysis was conducted on heavy metal data collected samples of two tiling categories. this analysis included the calculation of mean values, standard deviation (sd), and range. all statistical evaluations were performed using ibm spss statistics (v. 20). to evaluate the contamination of tailing, the concentration, contamination factor (cf), geo-accumulation index (igeo), and pollution load index (pli) were applied. results and discussion the concentration of heavy metals in tailings samples the concentration (amount) of heavy metals in unprocessed and processed tailings is presented in table 3. arsenic was detected in both unprocessed and processed samples, as well as in all heaps. in unprocessed samples, arsenic concentrations ranged from 12.993 to 80.531 mg/kg, with a mean of 32.873 ± 26.284 mg/kg. approximately 67% of the unprocessed tailings samples had arsenic levels exceeding the who/fao (2011) maximum acceptable limit of 20.0 mg/kg. in processed tailings, arsenic levels ranged from 7.243 to 61.116 mg/kg, with a mean of 24.390 ± 19.394 mg/kg. about 44% of the processed tailings samples exceeded the who/fao acceptable limit. overall, arsenic concentrations were lower in processed tailings compared to unprocessed tailings. previous studies (harmanescu et al., 2011; tóth et al., 2016) have indicated a strong correlation between arsenic (as), cadmium (cd), mercury (hg), lead (pb), and gold mining activities. the arsenic levels in this study were lower than those found in earlier research in ghana, where a maximum concentration of 8305 mg/kg was reported (ahmad and carboo, 2000), and in another study with a maximum concentration of 1752 mg/kg in gold mine tailings (bempah et al., 2013). high levels of arsenic contamination are concerning due to its potential health impacts, with previous epidemiological studies (tchounwou et al., 2003) highlighting a strong link between arsenic exposure and an increased risk of both carcinogenic and systemic health effects. lead has many different industrial, agricultural and domestic applications. it is currently used in the production of lead-acid based batteries, ammunitions, metal products (solder and pipes), and devices to shield x-rays (gabby, 2006). lead is the most systemic toxicant that affects several organs in the body including the kidneys, liver, east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 1-14 7 central nervous system, hematopoetic system, endocrine system, and reproductive system (tsai et al., 2017; pirkle et al., 1998). lead concentration in unprocessed tailing varied largely from 20.181 to 119.427 mg/kg with mean of 44.012 ± 37.091mg/kg. the concentration in processed tailing ranges from 18.219 to 97.233 mg/kg with mean of 38.402 ± 28.270 mg/kg. the detected levels in both unprocessed and processed are higher than the maximum acceptable limit (who/fao, 2011). the concentration in processed tailing is lower than in unprocessed tailing by the factor of 1.15. the values obtained in this study are lower than the one detected in similar study (ogola et al., 2002) where the level of pb in gold mining soils have been reported to be 510 mg/kg of pb concentrations in kenya. zn plays a key role during physiological growth and fulfills an immune function. it is vital for the functionality of more than 300 enzymes, for the stabilization of dna, and for gene expression (costa et al., 2023). although some iron enzymes are sensitive to iron deficiency (dallman, 1990), their activity has not been used as a successful routine measure of iron status. the most significant and common cause of anemia is iron deficiency (who/cdc, 2008). if iron intake is limited or inadequate due to poor dietary intake, anemia may occur. table 3: concentrations of heavy metals (mg/kg) sample no. concentration in unprocessed tailings concentration in processed tailings as pb cd fe zn cr as pb cd fe zn cr 1 13.782 31.681 4.413 22960.03 43.617 182.332 9.267 27.287 5.978 22011.47 40.200 179.174 2 23.161 119.427 6.261 24463.80 169.589 220.024 21.341 77.013 4.112 23414.64 171.118 118.321 3 26.567 20.181 3.833 25307.94 76.251 179.467 15.413 18.219 1.468 24000.12 66.726 137.226 4 75.978 23.138 3.528 30089.13 80.408 148.881 61.116 26.871 2.973 26242.00 78.842 142.474 5 13.922 28.864 3.913 22864.25 50.064 204.119 11.519 24.172 2.242 20177.43 44.221 144.387 6 23.199 97.233 6.230 24476.98 147.219 196.354 22.011 97.233 3.104 25221.25 74.544 124.933 7 25.726 21.386 3.877 25323.16 78.341 188.739 18.252 21.386 2.711 22824.77 81.663 110.439 8 80.531 24.188 4.148 30102.12 69.961 214.638 53.347 24.188 1.988 23446.43 52.194 178.642 9 12.993 30.014 4.418 23003.28 44.784 216.183 7.243 29.248 3.229 23684.40 44.007 199.573 mean 1 32.873 44.012 4.513 25398.96 84.470 194.526 24.390 38.402 3.089 23446.95 72.613 141.352 std ( ±) 26.284 37.091 1.022 2827.729 44.641 22.670 19.394 28.270 1.329 1748.619 40.240 30.726 who/fao (2011) 20.0 50.0 3.0 300 50 20.0 50.0 3.0 300 50 zinc concentration in unprocessed tailing ranges from 43.617 to 169.589 mg/kg with mean of 88.470 ± 44.641 mg/kg. the concentration of analyzed samples is lower than maximum acceptable limit by who/fao (2011). the concentration in processed tailing ranges from 40.200 to 171.118 mg/kg with mean of 72.613± 40.240 mg/kg. surprisingly, the concentration in unprocessed tailing is lower than of the tailings processed tailing. this is due to the existing in geochemical environment where mostly in mining sites acid is and they mobilize zinc from sulfide minerals, concentrating it in the processed tailings (miler et al., 2022). this redistribution lead to increase zinc concentrations in the processed material (gleisner and herbert, 2002). the values obtained in this study are higher than the value detected earlier in ghana (koranteng et east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 1-14 8 al., 2011), where the mean zn concentrations in the sand soil samples ranged between 4.17±1.23 mg/kg and 43.17±4.75 mg/kg. iron concentration in unprocessed tailing ranges from 22844.250 to 30102.120 mg/kg with mean of 25398.96 ± 2827.729 mg/kg. the concentration in processed tailing ranges from 22011.470 to 26242.00 mg/kg with mean of 23446.95 ± 1748.619 mg/kg. the concentration observed in this study in in line with similar study in nigeria (fagbenro et al., 2021) where the mean concentration was 20,560.4 ± 84.30. cadmium compounds are classified as human carcinogens by several regulatory agencies (iarc, 1993). cadmium is a severe pulmonary and gastrointestinal irritant, which can be fatal if inhaled or ingested. after acute ingestion, symptoms such as abdominal pain, burning sensation, nausea, vomiting, salivation, muscle cramps, vertigo, shock, loss of consciousness and convulsions usually appear within 15 to 30 min (baselt. and cravey, 1995). acute cadmium ingestion can also cause gastrointestinal tract erosion, pulmonary, hepatic or renal injury and coma, depending on the route of poisoning (baselt, 2000). cadmium concentration in unprocessed tailing ranges from 3.528 to 6.261 mg/kg with mean of 4.513 ± 1.022 mg/kg. about 100% of the analyzed samples have higher level than maximum acceptable limit by who/fao (2011). the concentration in processed tailing ranges from 1.988 to5.978 mg/kg with mean of 3.089 ± 1.329 mg/kg. about 44% of the samples analyzed have higher level than maximum acceptable limit by who/fao (2011). the values obtained in this study are lower than one detected in similar study (bitala et al., 2009) where the level of cd in gold mining soils have been reported to range between 6.4 to 11.7 mg/kg of cd concentrations in tanzania. chromium (cr) is a naturally occurring element present in the earth’s crust, with oxidation states (or valence states) ranging from chromium (ii) to chromium (vi) (jacobs and testa 2005). industries with the largest contribution to chromium release include metal processing, tannery facilities, chromate production, stainless steel welding, and ferrochrome and chrome pigment production. the main health problems seen in animals following ingestion of chromium (vi) compounds are irritation and ulcers in the stomach and small intestine, anemia, sperm damage and male reproductive system damage. also it connected with cardiovascular, gastrointestinal, hematological, hepatic, renal, and neurological effects as part of the sequelae leading to death or in patients who survived because of medical treatment (atsdr, 2008). chromium concentration in unprocessed tailing ranges from 148.881 to 220.024 mg/kg with mean of 194.526± 22.670 mg/kg. the concentration in processed tailing ranges from 110.439 to 199.573 mg/kg with mean of 141.352 ± 30.726 mg/kg. all samples analyzed detected higher level than maximum acceptable limit by who/fao (2011). the concentration in processed tailing is lower than in unprocessed tailing by the factor of 1.38. the values obtained in this study are lower than the one detected in similar study in oman (abdul-wahab and marikar, 2012) where the level of cr in gold mining soils reported to be 486 mg/kg in gold mine tailings. east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 1-14 9 heavy metals pollution levels geo-accumulation indices the calculated index of geo-accumulation (igeo) for the investigated trace metals in the tailings are illustrated in figures 1. the igeo values obtained range from -2.237 to 3.326 in unprocessed tailing and -0.970 to 3.3116 in processed tailings. the index of geo accumulation (igeo) was assessed based on the values proposed by müller (1969) and their igeo values estimated is found in the following increasing order in unprocessed tailing zn < fe < pb < cr < as < cd while in processed tailing was in the following increasing order zn < fe < cr < as < pb < cd. according to the müller scale, the calculated results of igeo values indicate that cd can be classified in class 4 (strong pollutes) for both unprocessed and processed tailings (figure 1). these findings differ from a previous study on the enrichment factor (igeo) of arsenic in surface sediments in malaysia (abdullah et al., 2020), which reported that 13% of the sampling stations were classified as moderately polluted, 52.2% as unpolluted to moderately polluted, and the rest as unpolluted. figure 1: geo-accumulation indices values for unprocessed and processed tailings contamination factor (cf) figure 2 shows the contamination factors (cf) for unprocessed tailings and processed tailing. the cf for unprocessed tailings and processed tailing for as, pb, cd, fe, zn and cr were observed in the ranges of 2.529 to 1.876, 2.201 to 1.920, 15.043 to 10.297, 0.538to 0.497, 0.889 to 0.764, and 2.161 to 1.571 respectively. east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 1-14 10 figure 2 contamination factors for unprocessed and processed tailings accordingly, tailing samples can be classified as exhibiting low or no contamination with respect to zn and fe for all sampling tailings. the results are lower than those detected earlier (fagbenro et al., 2021), where the average contamination factor for fe was 1.15 and zn was 1.06. for as, pb, and cr the cf is in the range1 ≤ cf < 3indicating moderate contamination cd, the cf is in the range cf ≥ 6 indicating very high contamination. the degree of contamination for unprocessed and processed tailing sample is 23.361 and 16.925 respectively. this indicates the tailings are considerable contaminate. for the modified degree of contamination the unprocessed tailing have the value of 4.671 which shows high degree of contamination and processed tailing has the value of 3.385 which shows moderate degree of contamination. these results concur with previous study (hamad et al., 2019), indicating the highest enrichment factor for cr, zn, pb and as were 25.05 (very high), 7.21 (moderate), 5.07 (deficiency to minimum) and 5.67 (deficiency to minimum) respectively. the pollution load index (pli) the pollution load index (pli) was estimated to better realize the pollution level. in addition, it also provides useful data to the decision makers on the pollution level of the area. the pli values calculated for tailing samples are found to 4.423 for unprocessed tailing and 2.807 for processed tailing which shows that the soils are polluted and the environment is deteriorated in their quality. this shows the site is strongly affected by mining activities and soils in this region is seriously contaminated by heavy metals. the values in this study are higher than those detected earlier (hamad et al., 2019), where the pli determined ranged from 2.58 to 3.63. conclusion & recommendations heavy metals do not degrade easily and can accumulate over time in soil, water, and biota, east afr. j. biophys. comput. sci. (2025), vol. 6, no. 1, 1-14 11 posing prolonged risks to plant and animal health and contaminating food and water supplies. the heavy metals like arsenic, cadmium and lead can accumulate in organisms and magnify through food chains, impacting human health and biodiversity. they can cause chronic health issues (e.g., cancer, neurological damage) from direct and indirect exposure is crucial, especially in populations near mining sites. soil is a major pool for contaminants as it encompasses ability to bond with various chemical materials and media for transportation of forms of various pollutants in the atmosphere, hydrosphere, and biomass. the results obtained in the present research of as, pb, cd, fe, zn and cr in soil sample collected around unprocessed tailing and processed tailing showed that soil quality in the mine and areas around the gold mining is degrading. the studied area is extremely contaminated due to many years of mining activities. our data disclose that cd, as, zn, pb and cr concentrations in soil samples are higher than who/fao maximum acceptable limits the pollution assessment methods showed that soils in the studied area are significantly contaminated by cd, as, zn, pb and cr, where the concentration in processed tailing is lower than in unprocessed tailing by the factor of about 1.38. thus, in future, based on the environmental quality criteria for soils, the site would need remediation. it is hereby recommended using plants and microorganisms to extract or stabilize heavy metals in contaminated soils, which can be cost-effective and sustainable over the long term. also there is a need to engage local communities in monitoring efforts and educating them about safe practices, reducing exposure risks and fostering awareness of potential health impacts. acknowledgment many thanks to staff at geological survey of tanzania (gst) staff members who allowed us to use their laboratory in analyzing the samples. references abdullah m. i. c., sah a. s. r. m., and haris h. 2020. geoaccumulation index and enrichment factor of arsenic in surface sediment of bukit merah reservoir, malaysia. trop. life sci. res. 31(3): 109–125. abdul-wahab s. and marikar f. 2012. the environmental impact of gold mines: pollution by heavy metals. open eng. 2:304–313. abrahim g. m. s. and parker r. j. 2008. assessment of heavy metal enrichment factors and the degree of contamination in marine sediments from tamaki estuary, auckland, new zealand, j. environ. monit. assess. 136: 227−238. agency for toxic substances and disease registry (atsdr), 2008. toxicological profile for chromium, u.s. department of health and human services, public health service atlanta, ga ahmad k. and carboo d. 2000. speciation of as(iii) and as(v) in some ghanaian gold tailings by a simple distillation method. water air soil pollut. 122(3–4): 317–26. aisen p., enns c. and wessling-resnick m. 2001. chemistry and biology of eukaryotic iron metabolism. int j biochem cell biol. 33: 940–959. ali m. m., ali, m. l., islam m. s., and rahman m. z. 2016. preliminary assessment of heavy metals in water and sediment of karnaphuli river, bangladesh. environ. nanotechnol. monit. manag. 5: 27–35. baker b.j. and banfield j.f. 2003. microbial communities in acid mine drainage. fems microbiol. ecol. 44: 139–152. banu z., chowdhury m., hossain m. and nakagami k. 2013. contamination and ecological risk assessment of heavy metal in the sediment of turag river, bangladesh: an index analysis approach. j. water resource prot. 5: 239-248. baselt r. c. 2000. disposition of toxic drugs and chemicals, chemical toxicology institute in man, 5th ed. foster city, ca. east afr. j. biophys. comput. sci. 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(2024), vol. 5, issue. 1, 51-67 *corresponding author: email: buchale.shishitu@yahoo.com, +251912798739 https://dx.doi.org/10.4314/eajbcs.v5i1.5s ethiopia; p. o. box 2228 keywords: exploitation rate; growth parameters; lake abaya; length at maturity; mortality rates; recruitment abstract the nile tilapia, oreochromis niloticus, is one of the most commercially important fish species in ethiopia. effective management is essential to sustaining their fisheries and providing benefits for the local communities. the study was aimed at determining the basic population characteristics (growth, mortality rates, and recruitment), size at first maturity, length at first capture, and stock status of o. niloticus in lake abaya. these basic quantitative population characteristics enable a fisheries manager to identify population changes resulting from fishing. the parameters were determined using length frequency data collected from 4089 samples of o. niloticus ranging from 23 to 47 cm in total length. the total length (tl) and total weight (tw) of o. niloticus samples were gathered between september 2021 and august 2022. the length-weight relationship parameters were (tw = 0.0157tl3.0192, r2 = 0.9603) and the condition factor k=1.69. the population parameters were determined using the elefan i routine in fisat software. estimated von bertalanffy growth parameters were (l∞) = 49.35 cm, growth curvature (k) = 0.36 yr-1, age at length zero (to) = -0.40, and growth performance index (փ') = 3.0.the estimated values of total natural and fishing mortalities were z= 1.34 yr-1, m =0.34 yr1,and f= 1.0 yr-1, respectively. the current exploitation rate (e) was0.74, which is higher than the optimal (e = 0.5) and indicates that o. niloticus in lake abaya was overexploited. in order to maintain the sustainability of the fish population, it is advised that the local authorities establish regulations for the management of o. noloticus in lake abaya. these regulations should include protecting the use of small fishing gear and safeguarding fish that are caught smaller than their length at first maturity. introduction the growth parameters of fish populations can be determined through direct evaluations of hard structures (otoliths, spines, or vertebrae) and indirect assessments based on length distribution data over time (gayanilo et al., 2002; panfili et al., 2002). length-based stock assessment tools are relatively more convenient in tropical and sub-tropical waters since the seasonal differences in the hard structures of these relatively warm waters are delicate and often present unclear band marks (sparre and venema, 1992; panhwar and liu, 2013). east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx length-based estimates of growth parameters and mortality rates of nile tilapia (oreochromis niloticus, l. 1758) in lake abaya, southern ethiopia buchale shishitu shija south ethiopia agricultural research institute, arba minch agricultural research center, arba minch, research article mailto:buchale.shishitu@yahoo.com https://dx.doi.org/10.4314/eajbcs.v5i1.5s east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 52 the analysis of fish stock population dynamics in tropical environments was made easier by the introduction of relative growth models and length-based stock assessment approaches (huxley, 1993; froese and binohlan, 2000). these techniques were used to evaluate lifehistory theories and produce empirical estimates of pertinent biological and fisheries parameters, including longevity and length at first maturity (stergiou, 2000; froese and binohlan, 2000). additionally, it aids in forecasting fish stock exploitation, which could be useful in choosing between different management decisions (da costa and araújo, 2003; froese, 2006; garcia and duarte, 2006; da costa et al., 2014; sáoliveira et al., 2015). fish population biology and ecology are reflected in growth and mortality factors, which are crucial for modeling fish stock population dynamics. these metrics, which offer important evidence on the fluctuation of fish size over time and the reduction in population biomass owing to fishing and/or natural causes, are essential inputs for stock assessments (pauly, 1983; sparre and venema, 1998). lake abaya is one of the rift valley lakes in ethiopia. currently, this lake is the 4th most important in the country in terms of fisheries, contributing about 8% of capture fisheries to national and local markets (gashaw and wolff, 2014). about four commercially important fish species are in lake abaya: nile tilapia (oreochromis niloticus), nile perch (lates niloticus), african catfish (clarias gariepinus), and bagrus docmac. these fish species are used as a source of income and livelihood for fishing communities in lake abaya. oreochromis niloticus is the most significant fish species and has a great contribution to the annual catch and yield of total landings. due to high demand for fish food and market prices, the fishing process takes place throughout the year with heavy fishing pressure and a continual trend of yield reduction. recent and updated information regarding the life history and population dynamics of o. niloticus stock in lake abaya is lacking, despite the lake's considerable ecological and socioeconomic significance. a good understanding of fish population dynamic show mortality, growth, and recruitment interact to affect abundance is required for informed fisheries management. even though significant stock assessment and population dynamics studies of o. niloticus stocks have been carried out in lakes tana (workiye et al., 2019), chamo (buchale et al., 2019; million tesfaye et al., 2021), hawassa (yosef et al., 2017), and langeno (genanaw et al., 2022), there is no comparable data regarding economically significant fish species in lake abaya. therefore, this study was intended at determining the basic population parameters (growth, mortality rates, and recruitment), size at first maturity, length at first capture, and stock status of o. niloticus in lake abaya. the results can provide baseline information for fishery managers and scientists to design fishery exploitation and management strategies for further exploration of o. niloticus stock in the lake. materials and methods study area lake abaya is the second-largest lake in ethiopia after lake tana, a highland lake, and east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 53 one of the two southernmost rift valley lakes. it is situated in south ethiopia regional state, between 5o55’9’’ and6o35’30’’ n latitude and 37o36’90’’ and 38o03’45’’ e longitude (fig. 1). the lake is 60 km long and 20 km wide, with a surface area of 1160 square kilometers. it has a maximum depth of 13 m and is found at an elevation of 1268 m, which makes it the largest rift valley lake. this lake contains several islands, the greatest of which is aruro; the others are gidicho, welege, galmaka, and alkali. its southwest shore is home to the village of arba minch, while the southern banks are part of nech sar national park. the principal perennial rivers that enter lake abaya are the harre, hamassa, bilate, gidabo, and galana rivers. figure 1. outline map of ethiopia with a detailed view on lake abaya and chamo (shape file downloaded from www.maplibrary.org) methods of sampling and data collection samples of o. niloticus were gathered from three cooperatives engaged in commercial fishing in lake abaya. from september 2021 to august 2022, samples of o. niloticus were randomly collected for 12 days each month at four commercial fishing landing sites (ella, hillo, langama, and gubena). employing a measuring board and a sensitive electronic balance, the total length and total weight of fresh fish samples were determined to the nearest 0.1 cm and 0.1 g, respectively. apart from the visual identification of sex by the examination of the gonads and abdominal dissection, sex was also identified by external features. http://www.maplibrary.org/ east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 54 data analysis length-weight relationship and condition factor the length-weight relationship was calculated using the power function described by le cren(1951). tw = 𝑎𝑇𝐿𝑏--------------------[1] where, tw = total weight (g), a = the intercept, tl =total length (cm), and b = the slope of lengthweight regression the fulton’s condition factor (k) is often used to reflect the nutritional status or well-being of an individual fish. it was calculated using the formula described by fulton (1904), which is indicated below. k = 𝑇𝑊 𝑇𝐿3 ∗ 100 ----------------------[2] where, k = fulton’s condition factor tw = total weight of fish in grams (g) tl = total length of fish in (cm) estimation of growth parameters the fisat ii, elefan i software’s k-scan technique was employed to evaluate the asymptotic length (l∞) and growth rate (k) based on the length frequency data. using pauly’s empirical formula (pauly, 1979), the theoretical age at zero (to) was computed. log (-t0) = −0.3922 − 0.2752 ∗ 𝐿𝑜𝑔(l∞) − 1.038 ∗ log(k)---------------[3] where, to= is the theoretical age at which fish would have at zero length. l∞ = asymptotic length, k= von bertalanffy growth constant growth performance indexes were calculated by munro and pauly(1984): φ′ = 𝐿𝑜𝑔(𝑘) + 2 ∗ 𝐿𝑜𝑔(l∞)--------[4] where, φ′ = growth performance index, k and l∞ are defined above the length at first maturity (l50) was computed as froese and binohlan’s (2000) equation: log(l50) = 0.8979 ∗ 𝐿𝑜𝑔(l∞) − 0.0782---[5] the longevity (a0.95)of the cohort was computed as (spare and venema, 1997). a0.95= to + 2.996 𝐾 -------------------------------[6] where, a0.95 is the age at which 95% of the cohort would be dead as a result of natural means; to = is the theoretical age at which fish would have at zero length; k = von bertalanffy growth constant estimated mortality parameters sparre and venema (1992) state that the total mortality (z) was estimated using a linearized length-converted catch curve. the natural mortality coefficient (m) was computed as follows using taylor’s method: m = −ln⁡(1−0.95) 𝐴0.95 ------------------------------[7] a0.95 indicates the age at which 95% of the population would die from natural causes. the east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 55 calculation of the fishing mortality (f) was done by qamar et al. (2016). 𝐹 = 𝑍 −𝑀 ---------------------------------[8] where, f = fishing mortality, z = total mortality, and m = natural mortality. the exploitation rate (e) was calculated as (georgiev and kolarov, 1962). 𝐸 = ⁡ 𝐹 𝑍 -------------------------------------------[9] the length at first capture (lc) was estimated from the equation of beverton and holt (1957), which applies the growth constants of vbgf, the mean length of the fish catch ( ), and the total mortality parameter (z): lc = − k( l∞− 𝑍 ) ------------------------------[10] the length at optimum cohort biomass or yield pre-recruitment (lopt) was estimated from l∞, k, and m using the beverton (1992) formula: lopt= l∞ ∗ ( 3 3+ 𝑀 𝐾 )------------------[11] where, l∞, k, and m are as defined above. results and discussions length-weight relationship and fulton’s condition factor the present study is conducted on a total sample of 4089 specimens (2344 females and 1745 males) of o. niloticus. the monthly pooled length-frequency data of o. niloticus specimens were grouped into two-centimeter intervals. the obtained fish samples had lengths ranging 23 to 47 cm (mean = 35 cm) and weights ranging from 190 to 1676 g (mean = 933 g). however, 97.6% of the catches were placed in the 25-41 cm range. the remaining 1% and 1.4% were less than 25cm and greater than 41cm, respectively. the most commonly observed value was the mid-length of 28 cm, which was followed by the length groups of 30 and 32 cm (fig.2). figure 2: size structure of o. niloticus in lake abaya. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 56 when comparing, the maximum total length (47cm) observed in the present study is relatively smaller than those reported for the same fish in lake chamo: 57 cmtl (yirgaw et al., 2000) and 53.4 cm tl (buchale et al., 2019), 48.5 cm tl in gilgel gibe i reservoir (mulugeta, 2013), and 48 cm tl in alwero reservoir (genanaw et al., 2017). however, the observed maximum length for o. niloticus in lake abaya is larger than those in lake langeno, 35.5 cm tl (genanaw et al., 2022), lake beseka (25.0 cm tl), and lake hawassa (29.0 cm tl) (yosef et al., 2017). fishing typically reduces fish size structures due to fishing gear selectivity and leads to fisheriesinduced evolution toward smaller sizes and earlier maturity (borrell, 2013). fish undergo a reduction in size and early maturation to replenish themselves before being eliminated by fishing when fishing pressure increases dramatically. the relationship between total length and body of o. niloticus was established with the use of a scatter plot diagram and power function (fig. 3). the relationship was described by the equation tl = 0.0157tl3.0192(r2 = 0.9603, r = 0.9799). a strong positive correlation was found between the length and weight of the o. niloticus population in lake abaya, as indicated by the correlation coefficient (r = 0.9799). the regression coefficient "b" was found to be 3.0192 when utilizing the best-fit power function regression to analyze the length-weight relationship. the power of the formula did not show a statistically significant deviation from the 3.0 hypothetical value(p > 0.05). this study showed an isometric growth of fish and a strong association between length and weight, as evidenced by the exponential value (b = 3.0192) and correlation coefficient (r = 0.9799), respectively. fish can grow in three different ways during their lives: isometric (b = 3), negative allometric (b< 3), or positive allometric (b> 3), depending on the deviation of b (nehemia and maganira, 2012). when “b” is greater than 3, the fish increase in weight more than an increase in length, whereas if it is less than 3, the fish becomes lighter for its weight. however, in an isometric growth scenario, the fish maintains its body form as it grows longer (riedel et al., 2007). the growth pattern of o. niloticus in lake abaya was isometric, based on the "b" value found in this investigation. the length-weight association of o. niloticus was found to be similar in some of the earlier studies: 3.03 in lake ziway (zenebe, 1988); 3.04 in lake langeno (gashaw and zenebe, 2008); 3.017 in the river nile (shalloof and elfar, 2017); 3.034 in the aulia dam (ahmed and abdel, 2016); and 3.09 in the lake victoria cage system (ngodhe and owuor, 2019). on the other hand, some of the previously reported studies showed positive allometric length-weight relationships of o. niloticus were 3.18 in lake chamo (buchale, 2020), 3.16 lake victoria (ngodhe and owuor, 2019), 3.19 in lake ziway (gashaw and zenebe, 2008), and 3.366 in lake naivasha (keyombe et al., 2017) while, 2.33 in lake naivasha (cishahayo et al., 2022), 2.89 in lake langeno (genanaw et al., 2022), 2.76 in alwero reservoir (genanaw et al., 2017), and 2.934 in lake ardibo (endalk et al., 2018) were some of the negative allometric length-weight relationships of o. niloticus. the value of b can vary annually due to a variety of factors, such as season, habitat, gonad maturity, sex, nutrition, stomach fullness, east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 57 health, preservation techniques, and environmental circumstances (bagenal and tesch, 1978; arslan et al., 2004; froese, 2006; yilmaz et al., 2012; ali et al., 2016). furthermore, disparities in fish growth patterns could also be associated with the species’ condition, phenotype, environment, and specific geographic region (tsoumani et al., 2006). figure 3: length-weight relationship of pooled o. niloticus in lake abaya. fulton’s condition factor as depicted in table 1, the monthly mean values of fulton's condition factor (k) for females, males, and combined sexes ranged from 1.58 to 1.77. for females, males, and combined sexes, the average k value was 1.70, 1.68, and 1.69, respectively. in o. niloticus of lake abaya, there was statistically no significant variation in k between the sexes or with the month's interaction (p > 0.05). the condition factor is a metric that represents the fish's physiological state with respect to feeding, spawning, and other elements of their overall health. according to blackwell et al. (2000), high condition factor values imply advantageous environmental conditions (including habitat and prey availability), while low values suggest less conducive environmental conditions. the ecological habitat of fish species can be evaluated using the condition factor, which is also highly affected by biotic and abiotic environmental factors (ayoade, 2011; onimisi and ogbe, 2015; abu and agarin, 2016).five categories were created by morton and routledge (2006) based on the k values: very bad (0.8–1.0), bad (1.0–1.2), balance (1.2–1.4), good (1.4–1.6), and very good (> 1.6). however, according to ayoade (2011), a fish in good health has a condition factor greater than one. in this study, the average value of the condition factors were 1.70, 1.68, and 1.69 for females, east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 58 males, and combined sexes, respectively. as previously mentioned, the condition factor in this study was more than 1.6, indicating that o. niloticusin lake abaya is doing quite well. table 1. mean monthly condition factor of females, males and combined o. niloticus months females males combined sexes sep-21 1.58 1.60 1.58 oct-21 1.68 1.66 1.67 nov-21 1.63 1.63 1.63 dec-21 1.61 1.59 1.60 jan-22 1.67 1.62 1.65 feb-22 1.71 1.69 1.70 mar-22 1.73 1.67 1.70 apr-22 1.71 1.71 1.71 may-22 1.77 1.75 1.76 jun-22 1.76 1.72 1.74 jul-22 1.77 1.77 1.77 aug-22 1.75 1.75 1.75 average 1.70 1.68 1.69 estimated growth parameters the o. niloticus in lake abaya was predicted to have von bertalanffy growth parameters of asymptotic length (l∞) and annual growth constant (k) of 49.35 cm and 0.36 yr-1, respectively. the estimated theoretical age at birth (to) was -0.40. the longevity (a0.95), the age at which 95% of the population would be dead as a result of natural means, was 8.72 years. the growth performance index phi (փ’) was estimated at 3.0 (fig. 4). the estimated value of l∞ in this study was lower than the estimates from the studies in lakes chamo, 55.0 cm (buchale et al., 2019), and victoria, 58.8 cm (njiru et al., 2004). however, compared to lakes langeno (35.7 cm; genanaw et al., 2022), tana (44.1 cm; workiye et al., 2019), victoria (46.24 cm; yongo et al., 2018), koka (44.5 cm; gashaw, 2016), and naivasha (42.0 cm; waithaka et al., 2020), the l∞ in this study was higher. it is possible that the various water bodies' varying environmental conditions account for the differences in estimations of the von bertalanffy growth parameters (l∞ and k) when compared to similar research. the size of the population and the ways in which fish adjust throughout their lives are other elements that influence growth. as noted by sparre and venema (1998), this could potentially vary throughout stocks and species and be impacted by various methods of analysis. similar species can have different growth rates in different habitats (lowe-mcconnell, 1982). the length characteristics (tlmax and l∞) may be influenced by genetics, resource availability, and population density. the fishing pressure is also a factor for change in the asymptote length (l∞) of fish in a given water body. if fishing gear is discriminatory and oriented toward harvesting larger fish, they may become rare in east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 59 overexploited fisheries, and the scarcity of these fish in a given sample will certainly underestimate the growth parameters. in comparison to lakes langeno, 2.61 (genanaw et al., 2022), ziway, 2.76 (gashaw, 2006), and naivasha, 2.57 (waithaka et al., 2020), the estimated growth performance index (փ’ = 3.0) in the current study was greater. on the other hand, the index in the present study was lower than in lakes chamo, 3.16 (million et al., 2021), and victoria, 3.14 (yongo et al., 2018). the most effective method for determining the average growth parameters of a specific species is to use the growth performance index, which should show comparable values when comparing several groups within the same species (gulland, 1983; sparre and venema, 1998). the availability of food, environmental factors, and fishing pressures can all have an impact on a fish species' growth performance index, in addition to the genetic composition that dictates the species' potential for growth (getabu, 1992). o. niloticus in lake abaya had an approximate lifespan of 8.72 years, which is comparable to the lifespan of o. niliticus in lake langeno, 8.9 years, as indicated in genanaw et al. (2022). both biological elements and environmental factors can have an impact on lifespan. fish life spans are significantly influenced by a variety of biological criteria, including sex, genetic makeup, diet, reproduction, age, and maturation, in addition to environmental influences including salinity, temperature, and predation (das, 1994). figure 4: elefan i k-scan routine fisat ii output for o. niloticus in lake abaya. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 60 estimated mortality parameters in order to estimate total mortality, a length composition data set was created and prepared for a linear regression analysis between the x and y variables (table 2). the mortality parameters were determined using a linearized length-based catch curve analysis. as indicated in figure 5, the slope of the regression line (b) is -1.34, and hence, the estimated total mortality rate (z) was 1.34 yr-1. the natural mortality rate (m) and fishing mortality rate (f) were 0.34 yr1and 1.0 yr-1, respectively. using these mortality estimates, the exploitation rate (e) was computed as 0.74, which indicates that o. niloticus in lake abaya is overexploited. table 2: parameters for length-based catch curve analysis length group (cm) x y catch k l∞ (cm) ∆t (l1,l2) (l1+l2)/2 t(l1+l2)/2 ln(c(l1,l2)/∆t) 23-25 40 0.36 49.35 0.22 24 1.85 5.21 25-27 450 0.36 49.35 0.24 26 2.08 7.54 27-29 884 0.36 49.35 0.26 28 2.33 8.13 29-31 752 0.36 49.35 0.29 30 2.60 7.87 31-33 529 0.36 49.35 0.32 32 2.90 7.41 33-35 394 0.36 49.35 0.36 34 3.24 6.99 35-37 279 0.36 49.35 0.42 36 3.63 6.51 37-39 237 0.36 49.35 0.49 38 4.08 6.18 39-41 243 0.36 49.35 0.60 40 4.62 6.01 41-43 222 0.36 49.35 0.76 42 5.29 5.68 43-45 57 0.36 49.35 1.05 44 6.17 3.99 45-47 2 0.36 49.35 1.71 46 7.47 0.16 total 4089 fish mortality can be attributed to both natural and anthropogenic factors. most of the natural mortality could be attributed to old age, diseases, and predation factors in the aquatic ecosystem. the natural mortality (m) in the present study is lower than the fishing mortality (f), and indicating that the primary cause of mortality for o. niloticus in lake abaya is attributed by fishing factors. when comparing the estimated values for mortality (f ˃m), it is possible to conclude that fishing mortality was a more important source of mortality for o. niloticus in lake abaya. a population dominated by mortality was also indicated by the z/k ratio of 3.72 estimated in this study. the population is growth-dominated if the ratio z/k is less than 1, mortalitydominated if it is greater than 1, and in equilibrium when growth and mortality are equal if it is equal to 1. if z/k = 2 in a mortality-dominated population, the population is considered lightly exploited (beverton and holt, 1957). according to beverton and holt’s (1957) general criteria, the z/k value in the current study indicated that the o. niloticus population in lake abaya was highly exploited. this is also revealed by the estimated high east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 61 exploitation rate (e= 0.74), which indicates a state of overexploitation. as per gulland’s (1971) assumptions, a sustainable yield is considered optimal if f is equal to m or if the rate of exploitation (e) is 0.5. if e>0.5, it is typically assumed that the stock has been overexploited. figure 5: linearized length-based catch curve of o. niloticus in lake abaya. length at first maturity (l50) and length at first capture (lc) were 27.68 cm and 27.97 cm, respectively. the optimum length (lopt) of o. niloticus in lake abaya was also estimated at 37.53 cm. the l50 and lc of o. niloticus in lake abaya were almost similar and vulnerable for fishing. based on the evidence shown in this study, o. niloticus in lake abaya is ready to be removed through fishing at its first spawning stage. catching fish with total length less than or equal to l50 is the main cause of overfishing, and it is recommended that the mesh size of fishing nets used in lake abaya should be increased to catch fish above 28 cm for conservation of the stock. when the results of virtual population analysis (vpa) were considered (fig. 6), fish with total a length of 27-32cm had more exposure to fishing gear, whereas fishing mortality was higher for fish with a total length above 39 cm. y = -1.3411x + 11.571 r² = 0.9072 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 l n (c (l 1 ,l 2 )/ ∆ t) average age t(l1+l2)/2 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 62 figure 6: estimated virtual population of o. niloticus in lake abaya. the length at first maturity (l50) of o. niloticus in the present study was higher than that of lakes chamo 23.6 cm (buchale et al., 2021), hayq 12.8 cm for females and 12.9 cm for males (tessema et al., 2019), langeno 16.62 cm (genanaw et al., 2022), and hawassa 20.8 cm for females and 20.3 cm for males (muluye et al., 2016). according to fryer and iles (1972) and lowe-mcconnell (1987), the size of maturation varies depending on demographic conditions and is influenced by both genes and environment. depending on the fishery's selectivity, fishing pressure can affect population structure, growth, and early maturation (jorgensen et al., 2007). in water bodies with high fishing pressure, the fish devote more resources to reproduction than to somatic body building (bandara and amarasinghe, 2018). according to jonsson et al. (2014), fish that live in harsh situations also exhibit early sexual maturity since this is a coping mechanism for maintaining maximal reproduction under stressful conditions. figure 7: the seasonal recruitment pattern of o. niloticus in lake abaya. estimated seasonal recruitment pattern and relative yield per recruitment the estimated recruitment pattern of o. niloticus in lake abaya was year-round, with one peak period (may)in the year (fig. 7). recruitment adds younger fish to the fishery east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 63 and can vary from year to year by orders of magnitude. the peak recruitment season of o. niloticus in the present study was similar to o. niloticus in lake langeno, as indicated in genanaw et al. (2022). the biology of tropical freshwater fish reproduction appears to be significantly influenced by patterns of rainfall and variations in water levels (wootton, 1990). the monthly average rainfall in the study area is higher in april, may, and october, which could be one of the probable reasons for the occurrence of a peak recruitment pattern for o. niloticus in may. figure 8: beverton and holt's relative yield per recruitment curve for o. niloticus in lake abaya. the degree to which the current rate of exploitation is optimal, below optimal, or excessive with respect to the population’s capacity for self-renewal was ascertained using the correlation curve between the exploitation rate and yield per recruitment. according to the estimated yield per recruitment curve, the current exploitation rate was 0.74 with a yield per recruitment of 0.029, the optimal exploitation rate (eopt) was 0.5 with a yield per recruitment of 0.05, and the exploitation rate for maximum yield (emax) was 0.421 with a yield per recruitment of 0.053 (fig. 8). it is evident that the o. niloticus population in lake abaya was overexploited because the present exploitation rate was higher than the ideal exploitation rate. in order to monitor and set regulations for o. niloticus fishing in lake abaya, the local authorities need to be aware of this circumstance. the fish that are collected should be the same size at which they have spawned, in order to preserve the sustainability of the fish population. conclusions & recommendations the growth pattern of o. niloticus in lake abaya was isometric, which implied that an increase in body length is proportional to body weight. the groups with mean lengths ranging from 25 cm to 41 cm accounted for east afr. j. biophys. comput. sci. (2024), vol. 5, no. 1, 51-67 64 approximately 97.6% of the total capture and significantly influenced the yield of fish. the average value of fulton’s condition factor was 1.70, 1.68, and 1.69 for females, males, and combined sexes, respectively, which implied that the wellbeing of o. niloticus in lake abaya was in a very good health condition. this study generated important information on population dynamics parameters (growth, mortality rates, and recruitment) and other crucial life-history characteristics that can serve as basic stock assessment tools for o. niloticus management in lake abaya. the asymptotic length (l∞) and growth rate (k) were 49.35 cm and 0.36 per year, respectively. the length at first capture (lc) was estimated at 27.97 cm, while the length at first maturity (l50) was estimated at 27.68 cm. based on the result, premature harvesting of fish (i.e. before reaching the intended size or first maturity) may alter the recruitment potential of the stock, which in turn may result in the exhaustion or collapse of the stock. the long lifespan in which 95% of the population would be dead as a result of natural means was 8.72 years. moreover, the current exploitation rate (e= 0.74) is higher than the optimal (e = 0.5) and indicates that o. niloticus in lake abaya was overexploited. based on results of this study, it is suggested that the fisheries management of the lake should include controlling or restricting the usage of small fishing gear in addition to reducing fishing efforts to ensure the sustainability of this commercially important acknowledgements the author is grateful to the southern agricultural research institute for providing financial support, the arba minch agricultural research center for allowing access to the necessary facilities, and livestock research staff members for their valuable assistance during the execution of the experiment. references abu o. m. g. and agarin o. j. 2016. length-weight relationship and condition factor of silver catfish (chrysichthys nigrodigitatus) from the lower reaches of the new calabar river niger delta. int. j. innov. stud. aquat. biol. fish. 2(4): 1-7. ahmed a. b. a and abdel m. k. 2016. length weight relationship and condition factor of nile tilapia oreochromis niloticus (trewavas, 1983) in the southern part of jebel aulia dam, white nile, sudan. int. j. agric. food sci. 4 (10): 286-289. ali r.a.s., elawad a.n., khalifa m.m. and el-mor m. 2016. length–weight relationship and condition factor of liza ramada from eastern coast of libya. int. j. fish. aquac. res. 2: 1–9. arslan m., yıldırım a. and bekta s. 2004. lengthweight relationship of brown trout, salmotruttal., inhabiting kan stream, çoruh basin, north-eastern turkey. turk. j. fish. aquat. sci. 4: 45-48. ayoade a. a. 2011. length-weight relationship and diet of african carp labeoogunensis (boulenger, 1910) in asejire lake southwestern nigeria. j. fish. aquat. sci. 6(4): 472-478. bagenal t.b. and tesch f.w. 1978. age and growth. in: methods for assessment of fish production in freshwaters, pp. 101-136 ibp. hand book no.3, blackwell, oxford, england. bandara k.v. and amarasinghe us. 2018. influence of fishing pressure and water level fluctuations on the reproductive biology traits of oreochromis niloticus (linnaeus, 1758) in irrigation reservoirs of sri lanka. asian fish. sci. 31:127-145. beverton r.j.h. 1992. patterns of reproductive strategy parameters in some marine teleost fishes. j. fish biol. 41: 137–160. doi: 10.1111/j.10958649.1992.tb03875.x beverton r.j.h. and holt s.j. 1957.on the dynamics of exploited fish populations, fisheries investigation series, vol. 19, ministry of agriculture, fisheries, and food, uk. blackwell b.g., brown m.l. and willis d.w. 2000. relative weight (w) status and current use in fisheries assessment and management. rev. fish. sci. 8:1-44. borrell b. 2013. ocean conservation: a big fight over little fish. nature 493: 597-598. east afr. j. biophys. comput. sci. 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(pisces: chilidae) in lake zeway, ethiopia. msc thesis, addis ababa university, 78 pp. keywords multiobjective decision-making; intuitionistic fuzzy decision set; goal programming; interactive penalty function. abstract many applicable problems have multi-goals that optimize simultaneously, and decision-makers set imprecise aspiration levels for each goal. although such types of problems solved by fuzzy optimization are common in the literature, intuitionistic fuzzy optimization techniques are more efficient to handle than fuzzy and classical optimization. this research study focused on establishing a novel method by combining the penalty function method with an interactive goal programming methodology for addressing multi-objective decision-making problems in an intuitionistic fuzzy environment. one of the challenge that exists in the literature of the optimization method under an imprecise decision environment is that it is not guaranteed to generate a pareto-optimal solution for the introduced problem. therefore, in order to ensure the pareto-optimality of the obtained solution, the suggested method has developed a new aggregation operator, an appropriate relaxation of the constraint set, and a well-structured extended yager membership function. in addition, unlike other methods in the literature, the suggested method gives decision-makers the option to penalize the most unsatisfied objective function at a specific attained solution instead of starting from scratch and working their way through the problem. to illustrate the proposed method, we used a numerical example. many real-world decision-making problems such as agricultural cropland allocation problems by moges et al. (2023a); basumatary and mitra (2022), transportation problems by tadesse et.al. (2023), water ∗ east afr. j. biophys. comput. sci. (2024), vol. 5, issue. 2, 41-57 | 41 demmelash mollalign moges1,∗, berhanu guta wordofa2, allen rangia mushi3 1department of mathematics, hawassa university, hawassa, ethiopia 2department of mathematics, addis ababa university, addis ababa, ethiopia 3department of mathematics, university of dares salaam, dares salaam, tanzania penalized intuitionistic fuzzy goal programming method for solving multi-objective decision-making problems 1. introduction research article corresponding author email address: danieldemelashalem@gmail.com +251913845944 https://dx.doi.org/10.4314/eajbcs.v5i2.4s resource allocation problems by sharma et.al. (2007), production planning decisionmaking problems by khan et.al. (2021), etc are defined as multi-objective programming problems (mopps). often, the input data used in these problems does not have exact numerical values because of various uncontrollable circumstances. to solve such types of mopps, the most appropriate and straightforward techniques are fuzzy optimization methods, which were introduced by bellman and zadeh (1970). many authors (tadesse et.al., 2023; jameel and radhi, 2014; kahraman et.al., 2016) have been more committed to apply fuzzy set tools for various application issues after bellman and zadeh (1970) provided a model to tackle fuzzy-multi-objective programming problems (fmopps). the core idea behind the widely used approach for solving fmopps in the literature is to transform the original fmopps into a crisp single-objective optimization model using aggregation operators and ranking accuracy approaches, and then solve it using classical methods (zimmermann, 2001; kahra-man et.al., 2016; bellman and zadeh, 1970). few papers have focused on developing new mathematical models for identifying fuzzy non-dominant solutions to fmopp in the fuzzy optimization environment. these new models were developed by applying different aggregation operators like max-min operator by bellman and zadeh (1970), γ-operator by zimmermann (2001), bounded min-sum operator by cheng et.al. (2013), and fuzzy-and operator by singh and yadav (2015) to convert the multi-objective functions into singleobjection functions. using the newly introduced concepts, numerous approaches and models have been developed for various theoretical and scientific fields (bogdana and milan, 2009; kassa and tsegay, 2018; tadesse et.al., 2023). however, when uncertainty results from vagueness, inaccurate data, or intentional judgments, the modeling capabilities of fuzzy set theory are limited. decisionmakers may also experience some hesitancy as a result of imprecise information, unawareness of customers, seasonal change, etc. these kinds of factors are critical to consider while building realistic, suitable models and solving decision-making problems (singh and yadav, 2015; razmi et.al, 2016; moges and wordofa, 2024; kumar, 2020; fathy et.al., 2023). to overcome these limitations, numerous researchers suggested various fuzzy extensions that expanded the conventional fuzzy set theory concepts. atanassov (1986) developed a novel concept called an intuitionistic fuzzy (if) theory which successfully addresses the limitation of fuzzy theory. since the if set can offer degrees of acceptance, hesitancy, and rejection, it has been found to be more helpful for handling imprecision in optimization procedures than fuzzy and crispbased models, (mollalign et.al., 2022; sharma et.al., 2023). angelov (1995) proposed a new model to determine the mn1 pareto-optimal solution based on intuitionistic fuzzy optimization (ifo) which is a direct extension of the fuzzy optimization technique put out by bellman and zadeh (1970). subsequently, numerous scholars such as (ghosh and kumar, 2014; moges et al., 2023a; rukmani and porchelvi, 2018a; bharati and singh, 2014; dey and roy, 2015; mollalign et.al., 2022; moges et.al., 2023b; bharati et.al., 2014) have been proposed different ifo methods to solve the domain of mopps utilizing the benefit of ifs tools. yager (2009) highlighted certain drawbacks of angelov (1995)’s method for determining the optimal choice for decisionmakers. he suggested a new approach by con1mn represent membership-nonmembership east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 42 verting the intuitionistic fuzzy decision environment (ifde) into a fuzzy decision environment using a convex combination of nonmembership and membership functions. by addressing the shortcomings of the angelov (1995) technique, dubey et.al. (2012) applied the yager (2009) strategy to solve the mopp. garai et.al. (2015) exposes the shortcomings of the dubey et.al. (2012) method by demonstrating how certain constraints in their model can impede the pursuit of the optimal solution or render the model impractical. they also suggest a new function by broadening the scope of non-membership and membership functions. as with fuzzy optimization, a problem in the ifo environment can be formulated as a two-step process to be solved. the first is to convert a multi-objective function into a crisp single-objective optimization model using an appropriate aggregation operator, and then solve this model using suitable optimization technique. the majority of the existing ifo methods in the literature for resolving mopp are based on the max-min operator, (moges et al., 2023a; dubey et.al., 2012; garai et.al., 2015). however, the max-min operator is not guaranteed to generate the pareto dominance solution, and there is always no compensation for the resulting solution. the compensatory of the developed aggregation operator has a critical role in the procedure of solving mopps and it affects the optimality of the resulting non-dominant solution. as a result, the mn pareto-solution might not be the result of a model that was developed using the max-min operator approach. the second limitation is that even if the ifo method generates a mn pareto-optimal solution under an ifde, there is not always a guarantee of a pareto-optimal solution to the given mopp due to the boundary problem. to overcome this difficulty, many researchers have proposed different approaches to fuzzy decision-making problems. but the two-phase method which used by lu et.al. (2015); dubois and fortemps (1999); wu and guu (2001); dubey et.al. (2012); tsegaye et.al. (2021); jiménez and bilbao (2009) is the most commonly applied approach for finding a pareto-optimal solution to mopps in fuzzy decision environment. a two-phase method means that in phase one, use the max-min operator technique and then use the meanoperator technique in phase two to improve the previous solution obtained by the maxmin operator approach. however, dubois and fortemps (1999) indicated that this kind of strategy is not entirely consistent because we need to switch from the max-min operator to the mean-operator at different stages, and they suggested a multiphasons for objective functions provides upper and lower tolerances to avoid decision deadlock. additionally, razmi et.al (2016) point out that in situations where a certain level of satisfaction is fully achieved, there might not be a guarantee that a fuzzy efficient solution is pareto-optimal. in order to generate the pareto-optimal solution, jiménez and bilbao (2009); razmi et.al (2016) extended the technique by wu and guu (2001) and developed a generic strategy based on the goal programming method. on the other-hand, mollalign et.al. (2022) demonstrate that there is no assurance that the imprecise environment approach put forward by razmi et.al (2016) will be the only method used to obtain the paretooptimal solution of mopp when using intuitionistic fuzzy hierarchical optimization. furthermore, the ifo approach offers upper and lower tolerances to prevent decision stalemate when defining membership/ satisfaction and nonmembership/ dissatisfaction for objective functions. the third limitation in the literature of ifo is that to determine upper and lower tolerance, researchers use the “payoff matrix” approach without consideration of underestimation or overestimation values of the nadir point. therefore, decision-makers may perceive the solution derived from this approach incorrectly. but the east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 43 interactive approach is helpful to a decisionmaker since it offers mechanisms for learning about a problem in the ifo. there are a few researchers that concern an interactive method for solving a different domain of mopps in an intuitionistic fuzzy decision environment, (hanine et.al., 2021; garai et.al., 2016). however, in the existing interactive method, decision-makers do not have the freedom to punish/ penalize the more unsatisfied objective function at each iteration when the current solution does not satisfy the dm, rather than solving the problem from scratch. by taking into account the aforementioned limitations, the key goal of this research study is to develop a general and powerful novel method for solving the multi-objective linear decision-making problem (moldmp) in an ifde using the combination of penalty function method, the interactive method, and the goal programming. additionally, the following points are specific and basic contributions of current researchstudy works: i. we formulated an if membership and nonmembership function by finding the correct ideal and nadir point to set boundary for intuitionistic fuzzy goals (ifgs). ii. we proposed an extended yagermembership function that eliminates the boundary value problem. ii. a new if aggregation operator is developed to convert moldmp into a single-objective decision-making problem. iii. using a new if aggregation operator, we proposed an ifg programming model to find a pareto-optimal solution for moldmp. iv. decision-makers provide an interactive penalty function method to punish unsatisfactory objective functions at the current solution. the rest of the paper is presented as follows: the basic concepts and terms related to the paper are presented in section 2. section 3 illustrates the mathematical formulation of if-moldmps and its ifg model. in section 4, we demonstrated the newly proposed method developed based on goal programming techniques and interactive penalty function method. the general framework or algorithm of the proposed method presented in section 5 and the numerical examples used to summarize and demonstrate the applicability of the introduced method are discussed in section 6. the results and discussion of the study are given in section 7. finally, the conclusion of the present work and its future scope are given in section 8. 2. preliminaries 2.1. intuitionistic fuzzy set definition 2.1. (atanassov, 1986; fathy et.al., 2023) an intuitionistic fuzzy set (ifs) ãi in a non-empty universal x is a set of ordered-triplets ãi = {< x, µãi (x), νãi (x) >: x ∈ x} where, µãi : x → [0, 1] represent the membership function or degree of belongingness and νãi : x → [0, 1] represent non-membership function or degree of non-belongingness of the element x ∈ x being in ãi , so that ∀x ∈ x, 0 ≤ µãi (x) + νãi (x) ≤ 1,. for any ifs ãi on x, πãi (x) = 1−µãi (x)−νãi (x) is the degree of indeterminacy of x ∈ ãi or x /∈ ãi . 2.1.1. operations over intuitionistic fuzzy sets assume that ãi = {< x, µãi (x), νãi (x) > |x ∈ x} and b̃i = {< x, µb̃i (x), νb̃i (x) > |x ∈ x} are any ifss on the universal set x, (husain et.al., 2012). 1. subset ãi ⊆ b̃i ⇐⇒ µãi (x) ≤ µb̃i (x) and νãi (x) ≥ νb̃i (x), ∀x ∈ x. east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 44 2. equal set: ãi = b̃i ⇐⇒ µãi (x) = µb̃i (x) and νãi (x) = νb̃i (x), ∀x ∈ x. 3. complementation: (ãi)c = {< x, νãi (x), µãi (x) > |x ∈ x}. to represent the minimum and maximum operator (that means: min and max operator), we use the symbols “∧” and “∨” respectively. 4. intersection: ãi ∩ b̃i = {< x, µãi (x) ∧ µb̃i (x), νãi (x) ∨ νb̃i (x) > |x ∈ x}. 5. union: ãi ∪ b̃i = {< x, µãi (x) ∨ µb̃i (x), νãi (x) ∧ νb̃i (x) > |x ∈ x}. 2.2. multi-objective programming problem assume that a vector-valued objective function f : ℜn → ℜk (f(x) = (f1(x), f2(x), f3(x) . . . , fk(x)), and constraint functions g : ℜn → ℜm (g(x) = (g1(x), g2(x), g3(x), . . . , gm(x)) are continuously differentiable for all decision vector x = (x1, x2, x3 . . . , xn) ∈ s is formulated in the following way: (tsegaye et.al., 2021; razmi et.al, 2016) min f(x) = (f1(x), f2(x), f3(x) . . . , fk(x)) t subject to: x ∈ s = { x ∈ ℜn gj(x) (≤,≥,=) 0, j = 1, 2, . . . ,m xi ≥ 0, i = 1, 2, . . . , n. } (1) definition 2.2. (li and hu, 2009) let a vector x∗ ∈ s be a feasible solution to mopp (1). then � x∗ is weakly pareto-optimal solution to mopp (1) if there doesn’t exist a new vector x ∈ s such that ft(x) < ft(x ∗) for all t = 1, 2, . . . , k. � x∗ is pareto-optimal (efficient) solution to mopp (1) if there doesn’t exist a new vector x ∈ s such that ft(x) ≤ ft(x ∗) for all t = 1, 2, . . . , k, and ft(x) < ft(x ∗) for some t. any pareto-optimal solution is weakly pareto-optimal but the converse is hold for convex optimization problem. assume that the feasible set s ̸= ø (or z = f(s) ̸= ø) is compact and ft(x),∀t, is continuous to unsure the pareto-optimal is exist for mopp (1). 3. mathematical formulation of problem 3.1. intuitionistic fuzzy multiobjective linear decision-making problem consider mathematical formulation of intuitionistic fuzzy multi-objective linear decision-making problem (if-moldmp) can be represented as: (rukmani and porchelvi, 2018a; basumatary and mitra, 2022; garai et.al., 2015) m̃ax (m̃in) f̃ i t (x) = cx+ d, t = 1, 2, . . . , k subject to: x ∈ s̃i = {x ∈ ℜn : g̃ii (x) (≤̃, ≥̃,≈) bi,x ≥ 0}, (2) where c ∈ ℜk×n, dt ∈ ℜk are deterministic parameters and the right-hand quantity is bi ∈ ℜ, i = 1, 2, . . . ,m. the if-version of classical inequality≤,≥ and equality = in the model (1) are given as ≤̃, ≥̃ and ≈, respectively. the function f̃ i t (x) and g̃ii (x) are if linear objective and constraints, respectively due to they have if aspiration levels set by decision-makers (dms). s̃i is if feasible convex region. 3.2. intuitionistic fuzzy goal model of if-moldmp in many real-life applications, the decision-maker is allowed to specify an imprecise aspiration-level for each of the constraint and objectives function in ifmoldmp (2). a goal with an imprecise east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 45 aspiration-level for an if objective and constraints can be treated as an intuitionistic fuzzy goal (ifg) in the ifde. let d̃i = {f̃ i 1 (x), f̃ i 2 (x), . . . , f̃ i k s} be a set of ifgs, having maximization (m1) with aspiration-level f̄t for t ∈ m1, ḡi for i ∈ n1 and minimization (m2) with aspiration-level f t for t ∈ m2, gi for i ∈ n2 for type of ifgs. hence, to determine the crisp/ deterministic optimal solution, we need (x), g̃1 i (x), g̃2 i (x), . . . , g̃im(x)|x ∈ to formulate the ifg model of if-moldmp (2) as: (moges et al., 2023a; razmi et.al, 2016) determine: x ∈ s̃i subject to: { ft(x) ≥̃ f̄t, gi(x) ≥̃ ḡi for t ∈ m1, i ∈ n1 ft(x) ≤̃ f t , gi(x) ≤̃ g i for t ∈ m2, i ∈ n2 (3) in order to find a p areto-optimal solution for if-moldmp (2) in the ifde, we need to determine a solution that simultaneously maximizes the level of satisfaction/ membership µt(ft(x)), µi(gi(x)) and minimizes the level of dissatisfaction/ nonmembership νt(ft(x)), νi(gi(x)) of the ifgs under the given feasible region, x ∈ s, according to angelov (1995) stated. based on this idea, the pareto-optimal and mn paretooptimal solution of if-moldmp (2) are defined as follows: definition 3.1. (razmi et.al, 2016; tsegaye et.al., 2021) a solution vector x∗ ∈ s̃i is said to be a pareto-optimal to if-moldmp (2) if there is no new-vector x ∈ s̃i such that f̃ i t (x)≤̃f̃ i t (x ∗) ∧ µi(gi(x)) ≥ µi(gi(x ∗)) ∧ νi(gi(x)) ≤ νi(gi(x) ∗),∀t = 1, 2, . . . , k,∀i = 1, 2, . . . ,m, f̃ i t (x)<̃f̃ i t (x ∗) ∨ µi(gi(x)) > µi(gi(x ∗)) ∨ νi(gi(x)) < νi(gi(x) ∗), for some t ∈ {1, 2, . . . , k}, i ∈ {1, 2, . . . ,m}. definition 3.2. (jafarian et.al., 2018; razmi et.al, 2016) a solution vector x∗ ∈ s̃i is said to be a mn pareto-optimal solution to if-moldmp (2) if there doesn’t exists another vector x ∈ s̃i such that µt(ft(x)) ≥ µt(ft(x ∗)) ∧ νt(ft(x)) ≤ νt(ft(x) ∗) ∧ µi(gi(x)) ≥ µi(gi(x ∗)) ∧ νi(gi(x)) ≤ νi(gi(x) ∗),∀t = 1, 2, . . . , k,∀i = 1, 2, . . . ,m, and strictly inequality holds for some t or i. 4. proposed solution method 4.1. extended yager-membership function in the ifde in the ifde, the nadir and ideal points are useful for estimating the range of degrees of satisfying (membership) and rejection (non-membership) for the objective function in the if-moldmp (2). to determine nadir and ideal points, we need to find the optimal solution for each objective function ft(x) subject to the given set of constraints. that means solving the following problem independently: min ft(x) subject to x ∈ s for t = 1, 2, 3, . . . , k (4) the solution obtained from model (4) we call as xb t is best solution, zb t = ft(x b t ) is objective value or aspiration-level for each t. zid = (zb 1 , z b 2 , . . . , z b k ) is an ideal point and znad = (z̄1, z̄2, . . . , z̄k) is nadir point of ifmoldmp (2) where, z̄t = max x∈p ∗ ft(x), p ∗ is pareto-optimal set. since p ∗ ⊂ s, we have max x∈s ft(x) ≥ z̄t,∀t = 1, 2, 3, . . . k. due to the difficulties in finding the nadir point, some scholars suggested a heuristicapproach called “payoff matrix”, but the reeast afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 46 sult obtained by this approach may be an underestimation or overestimation of the nadir point, isermann and steuer (1997). the best solution x̄b t is used to construct the payoff matrix as follows: f1(x) f2(x) . . . fk(x) xb 1 f1(x b 1 ) f2(x b 1 ) . . . fk(x b 1 ) xb 2 f1(x b 2 ) f2(x b 2 ) . . . fk(x b 2 ) ... ... ... . . . ... xb k f1(x b k ) f2(x b k ) . . . fk(x b k )  (5) if the best solutions xb t are unique for all t = 1, 2, 3, . . . , k, then the payoff matrix approach will never overestimate the nadir point znad, (isermann and steuer, 1997). however, if xb t not unique for at least one t, max{ft(xb 1 ), ft(x b 2 ), . . . , ft(x b k )} may overestimate the nadir point. when a component of the nadir point for an optimization problem is underestimated or overestimated in an ifde, it may result in unnecessary information about the pareto-optimal solution, and decision-makers use a wide-range. if the model (4) produces more than one best solution for any s ∈ {1, 2, . . . , k}, then underestimated or overestimated solutions of nadir point exist. to estimate the correct nadir point, we use two-steps in the proposed method. in step one, we solve the following optimization problem for each s, using σ = 1 k > 0. min fs(x) zb s + σ k∑ t̸=s ft(xt) zb t subject to: x ∈ s (6) let xbb s be a solution obtained from the model (6), and construct the payoff-matrix (5) using this solution instead of xb s . using this two-step approach, we find upper and lower-bounds for the membership and nonmembership functions of the objective function, which are used as degrees of rejection and acceptance of each ifgs. in the case of minimization problem, uµ t = max{ft(xb 1 ), ft(x b 2 ), . . . , ft(x b k )} and lµ t = min{ft(xb 1 ), ft(x b 2 ), . . . , ft(x b k )} considered as upper and lower-bound of membership functions, respectively. similarly, u ν t = uµ t and lν t = lµ t + ϵt(u µ t − lµ t ) where, 0 < ϵt < 1 for each t are upper and lowerbound of non-membership functions, respectively (bharati and singh, 2014; moges et.al., 2023b). lemma 4.1. the solution obtained from the model (6) never generates an overestimation of znad, (ehrgott, 2000; isermann and steuer, 1997). for minimization problem, membership (µt(ft(x))) and non-membership (νt(ft(x))) functions can be defined according to eqs. 7 and eqs. 8 respectively. µt(ft(x)) =  1 if ft(x) ≤ lµ t uµ t −ft(x) uµ t −lµ t if lµ t < ft(x) ≤ uµ t 0 if ft(x) > uµ t (7) νt(ft(x)) =  0 if ft(x) < lν t ft(x)−lν t uν t −lν t if lν t ≤ ft(x) ≤ u ν t 1 if ft(x) > uν t (8) now, to overcome the limitation of the angelov (1995) model, we first resolve the indeterminacy factors independently for each ifg using the yager (2009) approach. therefore, using the membership function µt(ft(x)) defined in eqs.7 and the non-membership function νt(ft(x)) defined in eqs.8, the new extended yager-membership function is defined as follows: for any λ ∈ [0, 1]. iλt (ft(x)) = (1− λ)µt(ft(x)) + λ(1− νt(ft(x))) for each t = 1, 2, . . . k. (9) without knowing any other details regarding the dm’s attitude during this study, we arrived at λ = 1 2 in our discussion that follows. the piece-wise linear yagermembership function for the minimization east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 47 problem shown in figure 1(a): and defined as: iλt (ft(x)) =  1 if ft(x) ≤ lµ t 1− 1 2 ϵt( ft(x)−l µ t lν t −l µ t ) if lµ t ≤ ft(x) < lν t 1 2 (2− ϵt) u µ t −ft(x) u µ t −lν t if lν t ≤ ft(x) < uµ t 0 if ft(x) ≥ uµ t (10) now, we need to expand the range of function iλt (ft(x)) = 1, for ft(x) ≤ lµ t to iλt (ft(x)) > 1, for ft(x) < lµ t to overcome the limitation of dubey et.al. (2012) model. suppose lmin t = min{lµ 1 , l µ 2 , . . . , l µ k} ± lµ t and umax t = max{uµ 1 , u µ 2 , . . . , u µ k } ± uµ t such that lmin t < lµ t ≤ ft(x) ≤ uµ t for each t = 1, 2, . . . , k. to extend the yagermembership function, choose two positive numbers, b1, b2 > 0, and relax the range from [0, 1] to [−b2, 1+ b1]. therefore, the extended yager-membership function for the minimization problem developed as shown in figure 1(b): and defined in the following way: ηt(ft(x)) =  b1(l µ t −ft(x)) lµ t −lmin t + 1 if lmin t < ft(x) < lµ t 1− 1 2 ϵt( ft(x)−lµ t lν t −lµ t ) if lµ t ≤ ft(x) < lν t 1 2 (2− ϵt) uµ t −ft(x) uµ t −lν t if lν t ≤ ft(x) < uµ t b2(ft(x)−uµ t ) uµ t −umax t if uµ t ≤ ft(x) ≤ umax t (11) figure 1: yager-membership function iλt (ft(x)), (aggarwal et.al., 2019) and extended yager-membership function ηt(ft(x)), (garai et.al., 2016) for the minimization problem the piecewise linear extended yagermembership function eqs. (11) has the following properties: � over the interval containing all possible values of the objective function, it is a strictly monotonic function. � it permits alternate point orderings with yager-membership function values outside of [0, 1]. � it is equivalent to the yagermembership function iλt (ft(x)) eqs. (10) on [lµ t , u µ t ] for each t. � if ft(x) < lµ t , then ηt(ft(x)) ≥ 1, and if ft(x) > uµ t , then ηt(ft(x)) ≤ 0. � it shows the level of satisfaction of the decision-maker for every objective function. additionally, we modified these piecewise 48 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 linear extended yager-membership functions ηt(ft(x)) as follows: based on the method suggested by wu and guu (2001) to solve mopp (1) under an ifde without introducing extra binary variables. ηt(ft(x)) = ηt(a 1 t ) + s1t (ft(x)− a1t ) + m−1∑ l=2 (slt − sl−1 t ) 2 (|ft(x)− alt|+ ft(x)− alt) (12) where, alt, l = 1, 2, 3, . . . ,m are the breaking/ jumping points of ηt(ft(x)), t = 1, . . . , k, the slope of line segment between alt and a l+1 t is given by slt = ηt(a l+1 t )−ηt(alt) al+1 t −alt for l = 1, . . . ,m− 1; t = 1, 2, . . . , k. 4.2. develop a new intuitionistic fuzzy (if) aggregation operator a number of logical operators are available in the ifde, enabling the combination of numerous objectives into a single objective. we employed the convex combination of the arithmetic mean-operator and the max-min operator on the extended yager-membership functions ηt(ft(x)) eqs. (11) in order to create a novel operator in the ifde. therefore, the new if aggregation operator is formulated as: ηd̃i (x) = δ mink t=1ηt(ft(x))+(1−δ) 1 k k∑ t=1 ηt(ft(x)), (13) where 0 < δ < 1 represent the degree of preference of dms. using this novel if aggregation operator and decision-makers’ preference value δ ∈ [0, 1], the if-moldmp (2) is transformed into a crisp single-objective optimization problem to determine the pareto-optimal solution based on eqs.(14). max x∈s ηd̃i (x) (14) therefore, using a non-negative variable qlt, the extended yager-membership function defined in eqs.(12), and the if aggregation operator defined in (13), the equivalent deterministic single-objective optimization problem of model (14) is formulated as follows: model i: max δα0 + (1− δ) k∑ t=1 αt subject to:  α0 + αt ≤ ηt(ft(x)) for t = 1, 2, . . . , k. ηt(ft(x)) = ηt(a 1 t ) + s1t (ft(x)− a1t ) + · · ·+ (sm−1 t − sm−2 t )(ft(x)− am−1 t + qm−2 t ) ft(x) + ql−2 t ≥ al−1 t for l = 3, 4, . . . ,m α0, αt, q l−2 t ≥ 0 for t = 1, 2, . . . , k; l = 3, 4, . . . ,m. x ∈ s  (15) 4.3. the intuitionistic fuzzy goal programming method the higher-value of ηt(ft(x)) is regarded as the best acceptable value for dms in the ifde. as a result, dms must minimize the under-achievement (negative-deviational) variable d−t by assigning weight w− t to each objective function t in the goal programming approach ηt(ft(x)) + d−t ≥ 1. therefore, the intuitionistic fuzzy goal programming (ifgp) east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 49 model of if-moldmp (2) is formulated as follows: model ii: min k∑ t=1 w− t d − t subject to:  ηt(ft(x)) + d−t ≥ 1 for t = 1, 2, 3, . . . , k x ∈ s d−t ≥ 0, ∑k t=1w − t = 1, w− t > 0  (16) 4.4. interactive penalty function method (ipfm) in an intuitionistic fuzzy decision environment (ifde), the interactive approach is very effective at solving if-moldmp (2). in this process, the algorithm generates an initial solution before consulting the dm and obtaining a new solution(s) if the dm is dissatisfied with the current one. let x∗ be the optimal solution of model i (15) or model ii (16). assume that the existing solution x∗ does not satisfy the dms. to discuss how the penalty function method is applied in the interactive method once dms update the problem for some objective functions, we considered the following figure 2 that shows the level of satisfaction and dissatisfaction by dms. furthermore, the figure 2 demonstrates how to determine a solution from a large space by relaxing the constraint set. the green region in the figure 2 represents dms who are completely satisfied with the current solution, while the red region represents dms who are dissatisfied, and the row depicts how the algorithm generates the best solution from a large space. figure 2: how penalty function method applied on minimization type problem definition 4.1. a vector x ∈ s is dm-feasible solution if ∀t ∈ 1, 2, . . . , k, ηλ d̃i (ft(x)) − ηλ d̃i (ft(x ∗)) ≥ γt, for nonnegative variable γt. where, x∗ is optimal solution to either model i (15) or model ii (16). let the set of dm-feasible solution be denoted by sdm and defined as sdm = {x ∈ s|ηλ d̃i (ft(x))− ηλ d̃i (ft(x ∗)) ≥ γt,∀t}. to find a preferable pareto-optimal solution based on x∗ to if-moldmp (2), we east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 50 solve the following optimization problem: max x∈sdm ,γt≥0 j∑ t=1 γt (17) now choose x ∈ s such that ηλt (ft(x)) − ηλt (ft(x ∗)) < γ2 t (i.e.,x /∈ sdm). the nonlinear penalty function is defined as p (x) =∑j t=1[max{0, ηλ d̃i (ft(x ∗))−ηλ d̃i (ft(x))+γ2 t }]2 meng et.al. (2011); jameel and radhi (2014) and satisfies: p (x) = { 0 if x ∈ sdm > 0 if x /∈ sdm (18) now, using the penalty function, we can transform it into unconstrained optimization, where the objective function is defined as: f (x, ci) = ∑j t=1 γt+ci( ∑j t=1[max{0, ηλt (ft(x∗))− ηλt (ft(x)) + γ2 t }]2) based on the penalty parameter ci > 0, we formulate the penalty optimization problem as follows: (pλ,ci) maxf (x, ci) subject to x ∈ rn, (19) the main benefit of this model is that, instead of starting from scratch, it will use a wide domain to improve the existing solution and attempt to discover a solution that satisfies dms by ignoring the non-update membership and non-membership functions. ipfm algorithm: initial step: � using current solution x∗ and γti = ηλ d̃i ( uµ t −lµ t 2 ), choose initial solution x1 ∈ s such that ηλt (ft(x1)) − ηλt (ft(x ∗)) < γ2 ti . that means: x1 /∈ sdm . � choose λ = 1 2 , c1 > 0, β > 1 and set i=1 main step: step i. using xi and γti solve the problem maxf (x, ci) subject tox ∈ rn and let call xi+1 be an optimal solution. step ii. if xi+1 be dm feasible solution, then stop x̂ = xi+1 and the corresponding decision vector γ̂ are optimal solutions to model (17). otherwise, put ci+1 = βci, i = i+ 1 and go to step i. theorem 4.1 (optimality test). let x̂ and γ̂ are optimal solutions to model (17). then i. if γt = 0,∀ t = 1, . . . k, then the pareto optimal solution to if-moldmp (2) in an ifde is x∗. ii. in an ifde, x∗ is not pareto’s optimal solution to if-moldmp (2) if at least one γt > 0. instead of x∗, pareto’s optimal solution to if-moldmp (2) is x̂. (analogous theorem proofs can be found in literature for instance see garai et.al. (2015, 2016)) 5. algorithm for penalized ifgp method based on the idea discussed above, we proposed a general framework or algorithm for finding pareto-optimal solutions for ifmoldmp (2) in an ifde. the proposed algorithm’s steps are as follows: step 1: solve each objective function independently under the constraint set. that means: solve model (4). step 2: if the solution xb t of model (4) is unique for each t, then go to step 3. otherwise, solve model (6) and use its solution xbb t instead of xb t , then go to step 3. step 3: construct the payoff matrix (see eqs. 5) and find the upper and lowertolerances of membership and nonmembership functions. step 4: formulate the extended yagermembership function in an intuitionistic fuzzy decision environment. see eqs. (11). east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 51 step 5: solve either model i (15) or model ii (16). if the decision-maker is satisfied with the current solution x∗, then stop, and the current solution x∗ is the pareto optimal solution to if-moldmp (2). otherwise, go to step 6. step 6: ask the decision-maker to change the membership and nonmembership functions for j ≤ k objective functions, then go to step 7. step 7: solve model 17 with the abovementioned algorithm for interactive penalty function method to get solutions x̂ and γt. then there are the following scenarios: case-i if γt = 0,∀ t = 1, . . . k, decisionmakers must adjust either δ for model i and weight of objective function for model ii or λ, then go to step 5. case-ii in an ifde, if at least one γt > 0, then pareto’s optimal solution to if-moldmp (2) is x̂. 6. numerical example consider the following intuitionistic fuzzy multi-objective linear decision-making problem (if-moldmp) that is given in an intuitionistic fuzzy decision environment: m̃ax f1(x) = −x1 + 2x2 m̃ax f2(x) = 2x1 + x2 subject to: x ∈ s =  −x1 + 3x2 ≤ 21, 4x1 + 3x2 ≤ 45, x ∈ r2 x1 + 3x2 ≤ 27, 3x1 + x2 ≤ 30, x1, x2 ≥ 0.  (20) following the proposed solution method discussed so far, we solve the given ifmoldmp (20) step by steps: � individual solution: xb 1 = (0, 7),xb 2 = (9, 3), and ideal point: (zb 1 , z b 2 ) = (14, 21) � using payoff matrix the upper and lower bounds are: uµ 1 = 14, lµ 1 = −3, lmin 1 = −6, umax 1 = 27 and uµ 2 = 21, lµ 2 = 7, lmin 2 = −10, umax 2 = 32 using a tolerances ϵ1 = 0.4, ϵ2 = 0.3. � the brake points are: a11 = −6, a21 = −3, a31 = 7, a41 = 14, a51 = 27 and its corresponding values are η1(a 1 1) = −b2, η1(a 2 1) = 0, η1(a 3 1) = 0.8, η1(a 4 1) = 1, η1(a 5 1) = 1 + b1 for objective function f1(x). a12 = −10, a22 = 7, a32 = 17, a42 = 21, a51 = 32 and its corresponding values are η2(a 1 2) = −b2, η2(a 2 2) = 0, η2(a 3 2) = 0.85, η2(a 4 2) = 1, η2(a 5 2) = 1 + b1 for objective function f2(x). � the extended yager-membership functions are: η1(f1(x)) = −0.0286x1 + 0.057x2 − 0.59q11 − 0.0514q21 + 0.61 and η2(f2(x)) = 0.074x1 + 0.037x2 − 0.033q12 − 0.048q22 + 0.227 � based on the proposed model (15), we formulated if-moldmp (20) as singleobjective optimization model: east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 52 model i: assign the value of δ ∈ [0, 1] max δα0 + (1− δ)α1 + (1− δ)α2 subject to  α0 + α1 + 0.0286x1 − 0.057x2 + 0.59q11 + 0.0514q21 ≤ 0.61 α0 + α2 − 0.074x1 − 0.037x2 + 0.033q12 + 0.048q22 ≤ 0.227 x1 − 2x2 − q11 ≤ 3, x1 − 2x2 − q21 ≤ −7 −2x1 − x2 − q12 ≤ −7, −2x1 − x2 − q22 ≤ −17 −x1 + 3x2 ≤ 21, 4x1 + 3x2 ≤ 45, x1 + 3x2 ≤ 27, 3x1 + x2 ≤ 30 x1, x2, α0, α1, α2, q 1 1, q 2 1, q 1 2, q 2 2 ≥ 0.  (21) � in a similar way, using the proposed model (16), we converted the given if-moldmp (20) into the following single-objective optimization model: model ii: assign the relative important of each objective function w− t minw− 1 d − 1 + w− 2 d − 2 subject to:  0.0286x1 − 0.057x2 + 0.59q11 + 0.0514q21 − d−1 ≤ −0.39 −0.074x1 − 0.037x2 + 0.033q12 + 0.048q22 − d−2 ≤ −0.773 x1 − 2x2 − q11 ≤ 3, x1 − 2x2 − q21 ≤ −7 −2x1 − x2 − q12 ≤ −7, −2x1 − x2 − q22 ≤ −17 −x1 + 3x2 ≤ 21, 4x1 + 3x2 ≤ 45, x1 + 3x2 ≤ 27, 3x1 + x2 ≤ 30 x1, x2, d − 1 , d − 2 , q 1 1, q 2 1, q 1 2, q 2 2 ≥ 0.  (22) now, using matlab-r2023 software to solve model i (21) and model ii (22), we obtained the pareto-optimal solution x1 = 6,x2 = 7, fval = 1.1311, f1(x ∗) = 8, and f2(x ∗) = 19 for the given if-moldmp (20) and shown in table 1. table 1: results for model i (21) and model ii (22) in different cases δ, w− t optimal solution optimal value model i δ = 0.36 α0 = 0,α1 = 0.83739,α2 = 0.929, x1 = 6,x2 = 7, fval = 1.1311 f1(x ∗) = 8, f2(x ∗) = 19 δ = 0.5 α0 = 0,α1 = 0.8374,α2 = 0.93, x1 = 5.991, x2 = 7, fval = 0.8837 f1(x ∗) = 8.009, f2(x ∗) = 18.982 δ = 0.8 α0 = 0.8777,α1 = 0,α2 = 0, x1 = 5.152, x2 = 7.282, fval = 0.7022 f1(x ∗) = 9.412, f2(x ∗) = 17.586 model ii w− 1 = 0.6, w− 2 = 0.4 d−1 = 0.10548,d−2 = 0.144, x1 = 4.800,x2 = 7.399,fval = 0.12089 f1(x ∗) = 9.998, f2(x ∗) = 16.882 w− 1 = 0.5, w− 2 = 0.5 d−1 = 0.1626,d−2 = 0.0700, x1 = 6.00,x2 = 6.999,fval = 0.1163 f1(x ∗) = 7.998, f2(x ∗) = 18.999 w− 1 = 0.3, w− 2 = 0.7 d−1 = 0.1626,d−2 = 0.0700, x1 = 6,x2 = 7.00, fval = 0.0978 f1(x ∗) = 8, f2(x ∗) = 19 east afr. j. biophys. comput. sci. (2024), vol. 5, no. 2, 41-57 53 7. results and discussion for different values of δ ∈ (0.35, 0.85) and w− 1 , w − 2 ≥ 0 with w− 1 + w− 2 = 1, the comparative work of the resulted efficient solution is given in table 1. let the optimal or objective value of model i (21) and model ii (22) be presented by fval. as shown in table 1, when the value of w− 2 (relative-weight of f2(x)) increases and the value of δ (degree of compensation), w− 1 (relative-weight of f1(x)) decreases, the preferable optimal value fval is obtained. thus, the optimal solution of both model i (21) and model ii (22) is identical, i.e., x1 = 6,x2 = 7, fval = 1.1311, which is the candidate pareto-optimal solution of if-moldmp (20). now to test the pareto-optimality, we need to formulate the following single-objective problem (23) based on eqs. (17) and solve it: max γ1 + γ2 subject to:  −0.0286x1 + 0.057x2 − 0.59q11 − 0.0514q21 − γ1 ≥ 0.2274 0.074x1 + 0.037x2 − 0.033q12 − 0.048q22 − γ2 ≥ 0.703 x1 − 2x2 − q11 ≤ 3, x1 − 2x2 − q21 ≤ −7 −2x1 − x2 − q12 ≤ −7, −2x1 − x2 − q22 ≤ −17 −x1 + 3x2 ≤ 21, 4x1 + 3x2 ≤ 45, x1 + 3x2 ≤ 27, 3x1 + x2 ≤ 30 x1, x2, γ1, γ2 ≥ 0  (23) when the model above (23) is solved using the matlab-r2023 program, γ1 = γ2 = 0 is the outcome. this suggests that the pareto-optimal solution to if-moldmp (20) is provided by the found solutions x1 = 6,x2 = 7. the suggested method, however, allows decision-makers to select the goal that must be accomplished first in order of importance. for instance, as δ ↗(increases), the value of f1(x) ↗ and the value of f2(x) ↘ (decreases), etc. 8. conclusion in this paper, the penalized intuitionistic fuzzy goal programming strategy has been proposed for finding pareto-optimal solutions to the if-moldmp in an intuitionistic fuzzy decision environment. when applied to optimization problems in an imprecise environment, the ifo methodology is among the most effective methods available, yielding more satisfactory outcomes than fuzzy and classical optimizations. the significant contribution of the proposed method is the development of an extended intuitionistic fuzzy interactive technique to determine the most preferred pareto-optimal for if-moldmp in an intuitionistic fuzzy environment. this technique combines the penalty function method with an appropriate intuitionistic fuzzy aggregation operator. when compared to the existing ifo method, the proposed method can choose from a set of compromise solutions that are both efficient and meet the dm’s preference for ifmoldmp. furthermore, the advantages of the proposed method are that there is no need to add an extra zero-one variable, it eliminates the limitation of overestimation or underestimation of the nadir point when establishing a reference point for decision-makers, and it guarantees that the existing solution x∗ satisfies the pareto-optimally condition. a future study could focus on applying the proposed solution method to different real-world application problems, such as water resource allocation and inventory control problems, and comparing the outcomes to existing optimization methods. east afr. j. biophys. comput. sci. 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(2024), vol. 5, no. 2, 41-57 57 introduction mathematical model formulation the modified mathematical model model formulation qualitative analysis of the modified model well-posedness steady state basic reproduction number local stability of disease free equilibrium global stability of disease free equilibrium endemic equilibrium point local stability of endemic equilibrium bifurcation analysis sensitivity analysis numerical simulations and discussion extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion introduction preliminaries intuitionistic fuzzy set operations over intuitionistic fuzzy sets multi-objective programming problem mathematical formulation of problem intuitionistic fuzzy multi-objective linear decision-making problem intuitionistic fuzzy goal model of if-moldmp proposed solution method extended yager-membership function in the ifde develop a new intuitionistic fuzzy (if) aggregation operator the intuitionistic fuzzy goal programming method interactive penalty function method (ipfm) algorithm for penalized ifgp method numerical example results and discussion conclusion introduction mathematical model formulation the modified mathematical model model formulation qualitative analysis of the modified model well-posedness steady state basic reproduction number local stability of disease free equilibrium global stability of disease free equilibrium endemic equilibrium point local stability of endemic equilibrium bifurcation analysis sensitivity analysis numerical simulations and discussion extension of the modified model into an optimal control optimal protection and hospitalization using modified model existence of an optimal control the hamiltonian and optimality system numerical simulations of optimal control problem optimal control comparisons and strategies conclusion *corresponding author: email: drpnatarajan123@gmail.com; phone: +251-969-454307 bibliography of aquatic sciences, fisheries and aquaculture in ethiopia girma tilahun1, natarajan, p1*, abebe getahun2 and tsegay teame3 1department of aquatic sciences, fisheries and aquaculture, hawassa university 2department of zoological sciences, addis ababa university 3department of biology, ambo university, ethiopia keywords: aquaculture; aquatic science; bibliography ; fisheries preface this bibliography of aquatic sciences, fisheries and aquaculture is prepared with the intention of providing opportunity for different users to easily search for references that concentrate on aquatic sciences, fisheries and aquaculture (asfa). it is a collection of both grey literatures and scientific articles published in scientific journals. the grey literatures include papers presented in conferences, symposia and workshops, phd dissertations and msc theses of various national and international universities submitted as academic requirement for graduation. it should be noted that there are many more monographs of these types that could be found mainly in different universities in ethiopia and not included in this bibliography. moreover, the scientific papers published in journals and included in this bibliography should be checked for reputability. as the bibliography contains grey literatures and published papers it can serve as source of relevant information and data useful for meta analysis on key topics/issues of asfa. it will also help the scientific community to enhance their teaching, research and extension activities. moreover, the long list of references included in the bibliography shows the immense contribution of prominent researchers that promoted, not only their carrier, but also their profession in the aforementioned three specialized fields. since the bibliography is a collection of research reports taken from different sources, there may be lack of consistency while writing the references. for instance ethiopian authors include full father name while writing most of the references, however, abbreviated father name is included whenever the original paper does not have full father name. finally it should be noted that this bibliography on asfa is brought out for the first time in ethiopia, and we are confident that it will be updated in due course through contributions and feedback from users and researchers in the field. introduction as human population is steadily expanding and is expected to increase from the current 7+ billion to 14 billion by 2080, the demand for food will be concurrently increasing. agriculture is the main food production sector and more than 85% of the people from developing nations, like ethiopia, depend on agriculture for livelihood. however, agriculture production alone cannot be reliable due to east african journal of biophysical and computational sciences journal homepage : https://journals.hu.edu.et/hu-journals/index.php/eajbcs hawassa university college of natural & computational sciences year 2021 volume xx no xx east afr. j. biophys. comput. sci., special issue, december 2021, 1-61 2 several factors and this warrants the search for additional food production sectors. it is in this context, fisheries and aquaculture have been identified as important additional food production sectors for enhancing the livelihood status of rural people and improve the local and national economy. countries all over the world are designing and developing new strategies to increase food production through fisheries and aquaculture. the search for little known fishing grounds through modern fish finders, increased number of crafts, gears and manpower have played major role for the increased capture fisheries production, and unsustainable production has also been the factor responsible for stagnating fish production in wild waters. this in turn resulted in the emergence of aquaculture. it is a known fact that aquaculture provides food, income and employment and livelihood for millions of rural people all over the world. in many countries, fish farming is a very important activity. in recent years aquaculture has made significant strides owing to the advancement of science and technology and as a result aquaculture production has increased many folds. aquaculture production which was just one million tons in 1950 has increased to 60 million tons in 2010 and reached 81.1 million tons of aquatic animals 32.4 million tons of aquatic algae and 26000 tons of ornamental seashells and pearls in 2020 to expand aquaculture, efforts are now being made to apply diversified aquaculture technologies and system and species diversification. several freshwater, brackish water and marine fish species have been successfully hatchery bread and grown under diversified aquaculture systems. to successfully organize research and development in aquatic sciences, fisheries and aquaculture, it is necessary to have knowledge on the work so far carried out on the subject in questions which would pave way for developing and designing new areas of research that would ultimately improve the production potential to ensure food security both quality and quantity. realizing this fact, several countries have published scientific bibliographies in the subject as a measure to provide information and to search gap areas for advanced research. from a review of literature it is seen that, most such bibliographies are confined to the works carried out in countries where fisheries and aquaculture has made significant progress. in ethiopia, aquatic sciences, fisheries and aquaculture is developing rapidly taking advantage of the rich water resources in the form of large lakes, rivers, reservoirs and small water bodies. it is also an imperative need that research and development must progress further, so that the rich water resources available in the country can be better utilized to enhance local and national economy and to improve the livelihood status of the rural farmers. furthermore, the ecological health and integrity of the ethiopian water bodies should also be studied to ensure sustainability of the ecosystem services. we sincerely hope that the present bibliography on aquatic sciences, fisheries and aquaculture will help students and researchers to identify and concentrate more on gap areas of research in these areas. the current effort seems to be the first bibliography on aquatic sciences, fisheries and aquaculture in the country. it includes more than 1250 papers published in scientific journals, book of abstracts, seminar/conference proceedings, technical bulletins and reports, m.sc and phd theses. the abbreviations of east afr. j. biophys. comput. sci., special issue, december 2021, 1-61 3 journals have been listed according to the world list of scientific periodicals. the bibliography is not claimed to be complete and the scope of the bibliography has been limited to the works carried out in ethiopia. acknowledgements the cooperation of college of natural and computational sciences of the hawassa university is fully acknowledged for the immense contribution made to the successes of this work. references abayneh ataro, taddese wondimu and chandravanshi b.s. 2003. trace metals in selected fish species from lakes hawassa and ziway, ethiopia. sinet ethiop. j. sci. 26(2):103–114. abdurhman kelil 2002. users’ attitudes toward fisheries management in lake ziway, ethiopia. m.sc. thesis, norwegian college of fishery science, university of tromso, norway, 54p. abebaw wondie 2006.temporal dynamics of biomass and primary production of phytoplankton in relation to some physico-chemical factors in lake horaarsedi, ethiopia. m.sc. thesis, addis ababa university, ethiopia, 85pp. abebe ameha and alemu assefa 2002. the fate of the barbs of gumara river, ethiopia. sinet ethiop. j.sci. 25(1):1-18 abebe ameha 2004. the effect of birbira, milletiaferruginea (hochst.) on some barbus spp. (cyprinidae, teleostei) in gumara river (lake tana), ethiopia. m.sc. thesis, addis ababa university, ethiopia. 62pp. abebe ameha, belay abdissa and teferi mekonnen 2006. abundance, length-weight relationship and breeding season of clariasgariepinus (teleostei: clariidae) in lake tana, ethiopia. sinet, ethiop. j. sci. 29(2):171-176. abebe chaffo, lema zewedu and endrias geta 2014. market chain analysis of koka reservoir fish in ethiopia. in: brook lemma and seyoummengistou (eds). water reservoir in ethiopia: ecology and their benefits. 6th annual conference of the ethiopian fisheries and aquatic sciences association (efasa), mekelle, pp. 22-55. abebe cheffo, eyob bezabeh, mesay yami, yared mesfin and alemayehu wubie 2019. value chain analysis of fish production and marketing in lake tana, ethiopia. abstract, 15. international conference on aquatic resources and aquaculture for sustainable development (icar-aqua 2019), hawassa university, hawassa. abebe getahun 1987. food and size composition of epinepheluschlorostigma (pisces: serranidae) from some coastal areas of the ethiopian red sea. m.sc. thesis, addis ababa university, addis ababa, ethiopia, 63pp. abebe getahun 1990. laboratory manual for vertebrate zoology, marine biology and fisheries department, asmera university, asmera. abebe getahun 1991. frozen fish fillets: alternative for fresh fish utilization in the marine fisheries of ethiopia. fao fisheries report no. 467(suppl). expert consultation on fish technology in africa, accra, ghana. abebe getahun 1991. the red sea: an annotated bibliography. marine biology and fisheries department, asmara university, asmara. abebe getahun and stiassny, m.l.j. 1998. the freshwater biodiversity crisis: the case of the ethiopian fish fauna. sinet, ethiop. j. sci. 21(2):207-230. abebe getahun 1998. diversity and distribution of the genus garra(piscs: cyprinidae) in africa. 78th annual conference of the american society of ichthylogists and herpetologists, guelph, ontario, canada abebe getahun 1998. the rea sea as an extension of the indian ocean. pp. 277-283. in: sherman et al. (eds.). large marine ecosystems of the indian ocean: assessment, sustainability and management. blackwell science. abebe getahun 2000. systematic studies of the african species of the genus garra (pisces: cyprinidae). ph.d. thesis, city university of new york, 478 p. abebe getahun 2001. lake afdera: a threatened saline lake in ethiopia. sinet, ethiop.j.sci. 24(1): 127131. abebe getahun 2002. diveristy and conservation status of the ethiopian freshwater fishes. 3rd pan africa conference on fish and fishereis association (paffa) cotonou, benin, nov. 2003 abebe getahun 2003. the nile basin: reverine fish and fisheries. department of biology, addis ababa university, ethiopia. 25 p abebe getahun 2005. description of freshwater ecoregions of ethiopia (northeastern rift, ethiopian highlands, red sea coastal, shebele-juba catchments). in: thieme et al. (eds.) freshwater ecoregions of africa and madagscar: a conservation assessment. pp.181-183; 253-255; 351-352; 352353). inland press, 1718 connecticut avenue, nw, suite 300, washington, dc. 20009 east afr. j. biophys. comput. sci., special issue, december 2021, 1-61 4 abebe getahun 2007. an overview of the diversity and conservation status of the ethiopian freshwater fish fauna. j. afrotrop. zool.(special issue): 87-96. abebe getahun 2007. genus garra hamilton, 1822. pp.532-535. in: stiassny, m.l.j., teugels, g.g. and hopkins, c.d. (eds): fresh and brackishwater fishes of lower guinea, west central africa, vol.1. institute de recherché pour le development; museum national d’histoire naturelle, muse royal de1’afrique central abebe getahun 2011. a unique species flock in lake tana-the labeobarbus complex, species in spot light, in: biodiversity of life in african freshwatersunder threat; darwall et al. (eds). iucn, gland, switzerland and cambridge, uk; pp. 82-85. abebe getahun 2015. ethiopian fishes: from diversity to utilization. abstract, 4.in: sustainable fish production, societal welfare and development goals of ethiopia, 7thannual conference of ethiopian fisheries and aquatic science association (efasa), february 7-8, 2015, arba minch university, arbaminch, ethiopia, abebe getahun 2017. freshwater fishes of ethiopia: diversity and utilization. view graphics and printing plc. addis ababa, ethiopia; 349 pp. abebe getahun and alemayehu negassa 2004. impact of exotic fish species tilapia zillii (gervais, 1948) on the native oreochromis niloticus in lake ziway, ethiopia. international conference on assessment and control of biological invasion risks. augest 26-29, 2004, yokohama national university, yokohama, japan. abebe getahun and abebe ameha (eds). 2006. field and laboratory techniques for zoological museum collections. manual on methods of collection, preservation and management. zoological natural history museum, addis ababa university, addis ababa, 91p. abebe getahun, belay abdissa, eshete dejen, minwyelet mingist, shewit gebremedhin, and wassie anteneh 2021. sustainability of labeobarbus spp. in lake tana, ethiopia. imperiled: the encyclopedia of conservation https://doi.org/10.1016/b978-0-12821139-7.00035-0. abebe getahun, brook lemma and seyoum mengistou 2018. first directory of wetlands of ethiopia. in collaboration with the ethiopian wildlife and natural history society and wetlands international. eclipse publishers, addis ababa, ethiopia, 562p.. abebe getahun, eshete dejen and wassie anteneh. 2008. fishery studies of ribb river, lake tana basin, ethiopia, final report to world bank, e1573, vol. 2, addis ababa, ethiopia. abebe getahun and eshete dejen 2012. fishes of lake tana: a guide book. addis ababa university press, 140p abebe getahun and eshete dejen 2020. freshwater fish diversity and its role in improving the livelihood of communities in ethiopia. in: fao. 2020. biodiversity: the central role in the sustainable development of africa, nature &faune. 33(1): 4956. abebe getahun, mulugeta wakjira and dorothy wanja nyingi 2020. social, economic and management status of small-scale fisheries in omo river delta and ethiopian side of lake turkana, southern ethiopia. ecohydrology & hydrobiology 20: 323332 abebe getahun and lazara, k.j. 2001. lebias stiassnyae: a new species of killifish from lake afdera, ethiopia (teleostei: cyprinoidea). copeia. 1:150-153 abebe getahun and stiassny, m.l.j. 1998. the freshwater biodiversity crisis: the case of the ethiopian fish fauna. sinet, ethiop. j. sci. 21(2):207-230. abebe getahun and stiassny, m. 2004. the diversity and distribution of the african species of the genus garra (piscs: cyprinidae) with the monophyly of the genus. 11th congress of the european ichthyological society, september 6-10, 2004, tallinn, estonia. abebe getahun, stiassny, m.i.j. and teugels, g.g. 2004. a new species of varicorhinus (ostariophysi: cyprinidae) from west-central africa. cybium 28(2): 159-162.. abebe guadie and kassa tadele 2016. assessing the impact of existing and future water demand on economic and environmental aspects (case study from rift valley lake basin: meki-ziway sub basin), ethiopia. international journal of waste resources. 6:2 doi: 10.4172/2252-5211.1000223 abebe tadesse. 2007. the effect of stocking density and supplementary feeding on growth performance of nile tilapia [oreochromis niloticus l., 1758)] in cage culture system in lake elen, ethiopia. msc thesis, addis ababa university, ethiopia. abebe tadesse, abebe getahun and seyoum mengistou 2010. the effect of stocking density and supplementary feeding on growth performance of nile tilapia (oreochromis niloticus linneaus, 1758) in cage culture system in lake elen, ethiopia. in: seyoum mengistou and brook lemma (eds.). management of shallow waterbodies for improved productivity and peoples' livelihoods in ethiopia. efasa, addis ababa university printing press, addis ababa, pp 48-60 abebe tadesse, beatrix alsanius and abebe getahun 2015. growth and metabolic response of nile tilapia (o.niloticus l.) for new aquaponics diet formulated from guizotiaabyssinia l. and major east afr. j. biophys. comput. sci., special issue, december 2021, 1-61 5 nitrogen source. abstract, 33. in: sustainable fish production, societal welfare and development goals of ethiopia, 7thannual conference of ethiopian fisheries and aquatic science association (efasa), february 7-8, 2015, arba minch university, arba minch, ethiopia. abebe, y., bitew, m., ayenew, t., alo, c., cherinet, a. and dadi, m. 2018. morphometric change, detection of lake hawassa in the ethiopian rift valley. water 10 (5): 625 abel weldetinsaea, mekibib dawit, abebe getahun, patil, h.s., esayas alemayehu, melaku gizaw, moa abate and daniel abera 2017. a neugenicity and clastogenicity in freshwater fish oreochromis niloticus exposed to incipient safe concentration of tannery effluent. ecotoxicology and environmental safety 138: 98-104. abera cheffo, gashaw tesfaye and hussien abegaz 2011. fish marketing, challenging and opportunities of fishery development in tendaho reservoir, afar, ethiopia. in: natarajan et al. (eds). proceedings of the international conference on ecosystem conservation and sustainable development (ecocasd, 2011), ambo university, ambo, ethiopia, 473p. abera degebassa 2004. solar drying of fish fillet using tent in ziway. in:proceedings of the 12th annual conference of the ethiopian society of animal production (esap) addis ababa, ethiopia. abera degebassa 2010. technical and socio-economic characteristics of fishing activities, fish handling and processing in ethiopia. in:seyoum mengistou and brook lemma (eds). management of shallow waterbodies for improved productivity and peoples' livelihoods in ethiopia. efasa, addis ababa university, addis ababa, pp 104-107. abera degebassa and tesfaye alemu aredo 2010. a comparative study on the effect of three drying methods for better preservation of fish. in: seyoum mengistou and brook lemma (eds.). management of shallow waterbodies for improved productivity and peoples' livelihoods in ethiopia. efasa, addis ababa university, addis ababa, pp 117-122 abera degebassa and yared tigabu (2009). on-station evalution of cold cooked and fried marinatedfish. in: proceedings of the first annual conference of efasa, held at ziway fisheries resources research center, ziway, ethiopia, pp 19-24. abera degebassa, seyoum badee and yared tigabu 2008. effect of fish meal processing on feed quality for livestock in ziway, oromia (ethiopia), in:proceedings of the 16th annual conference of the ethiopian society of animal production (esap), addis ababa, ethiopia, pp 129-136. abera degebassa, yared tigabu ahmed mohammed 2008. evaluation of chorkor, smoker and altoona oven for smoking nile tilapia (oreochromis niloticus) fish at ziway, ethiopia, in: proceedings of the 16th annual conference of the ethiopian society of animal production (esap), addis ababa, ethiopia, pp. 137-142. abera hailu degaga 2019. water hyacinth (eichhornia crassipes) biology and its impacts on ecosystem, biodiversity, economy and human well-being. abstract, 7. international conference on aquatic resources, aquaculture and sustainable development (icar-aqua 2019), hawassa university, hawassa. abile teshita and ayalew wondie 2014. the impact of impoundment on downstream macroinvertebrate communities at koga irrigation dam, west gojam, ethiopia. int. h.sci. res., 3 (6): 544-552. abnet woldesenbet and seyoum mengistou 2018. benthic macroinvertebrates diversity and distribution in relation to abiotic factors in the littoral zone of lake ziway, ethiopia. int. j. adv. res. biol. sci. 5 (11): 62-75 abnet woldesenbet, elias dadebo and yosef teklegiorgis 2015. feeding habits and concentration of trace metals in different organ of nile tilapia (o.niloticus l., 1758), (pisces, cichilidae) in lake abaya, ethiopia, abstract, 32. in: sustainable fish production, societal welfare and development goals of ethiopia. 7th annual conference of ethiopian fisheries and aquatic science association (efasa), february 7-8, 2015, arbaminch university, arba minch, ethiopia abraha gebrekidanasgedom, mulu berhe desta and yirgaalem weldegebriel gebremedn 2012. bioaccumulation of heavy metals in fishes of hashenge lake, tigray, northern highlands of ethiopia. am. j. chem. 2(6):326-334 abraha gebrekidan, mekonen teferi, amanual hadera, tsehaye asmelash, tadese dejene, solomon tesfay, kindeya gehiwet, kassa amare, deckers j.s., declerck s.a.j., de meester l., and van der bruggen b. 2015. temporal variation in water quality of irrigation reservoirs in the semi arid highlands of tigray, northern ethiopia. abstract, 19. in: sustainable fish production, societal welfare and development goals of ethiopia, 7th annual conference of ethiopian fisheries and aquatic science association (efasa). february 7-8, 2015, arba minch university, arba minch, ethiopia abraham, t., woldemicheal, a., muluneh, a. and abate, b. 2018. hydrological responses of climate change on lake ziway catchment, central rift valley of ethiopia. j earth sci. clim. change. 9: 474. doi: 10.4172/2157-7617.1000474 east afr. j. biophys. comput. sci., special issue, december 2021, 1-61 6 abrehet kahsay, shewit gebremedhin and belayneh ayele 2015. effect of the main municipal canal effluent on the head of blue nile river water quality using aquatic macroinvertebrates as bio indicators. abstract, 22. in: sustainable fish production, societal welfare and development goals of ethiopia. 7th annual conference of ethiopian fisheries and aquatic science association (efasa), february 7-8, 2015, arba minch university, arba minch, ethiopia adamneh dagne 2004. zooplankton abundance and species composition in the ethiopian rift valley lake -lake ziway, m.sc. thesis unescoihe, delft, the netherlands. adamneh dagne 2010. zooplankton community structure, population dynamics and production and its relation to abiotic and biotic factors in lake ziway, ethiopia. ph.d.thesis, wien university, austria. adamneh dagne 2012. overview of sebeta national fishery and other aquatic life research center. in: brook lemma, abebe getahun and seyoum mengistou (eds). the role of aquatic resources for food securitin ethiopia. proceedings of the fourth annual conference of ethiopian fisheries and aquatic sciences association (efasa) addis ababa university, addis ababa, pp. 215-230 adamneh dagne and abeba woldegebriel 2014. integration of fish production in multipurpose water bodies in tigray region. in: brook lemma and seyoum mengistou (eds). water reservoir in ethiopia: ecology and their benefits. 6th annual conference of the ethiopian fisheries and aquatic sciences association (efasa), mekelle, pp 56-80 adamneh dagne, aschalew lakew, fasil degefu and abeba woldegebriel 2007. growth performance and economic returns of male monosex and unsexed tilapia (oreochromis niloticus l.) culture in ponds fed on wheat bran. in: tamrat degefa and fekede feyissa (eds). pastoral livestock systems: opportunities and challenges as a livelihood strategy, pp. 173-181. proceedings of the 15th annual conference of the ethiopian society of animal production (esap), october 4-6, 2007, addis ababa, ethiopia. adamneh dagne., herzig, a., jersabek, d. and zenebe, t. 2008. abundance, species composition and spatial distribution of planktonic rotifers and crustaceans in lake ziway (rift valley). int. rev. hydrobiol. 93(2): 210-226. adane sirage 2006. water quality and phytoplankton dynamics in legedadi reservoir, ethiopia. m.sc. thesis, addis ababa university, 109p. admasu tassew 2007. assessment of biological integrity using physico-chemical parameters and macro invertebrate community index along sebeta river, ethiopia. m.sc. thesis, addis ababa university adugna babu and bogale teferi 2015. assessment of human induced threats to warameda wetland, dale woreda, southern ethiopia. int. j. fauna biol. stud. 2 (6): 25-33. adugna kaba 2015. assessment of physico-chemical and biological characteristics of selected fish ponds in west shoa zone, ethiopia. m.sc. thesis ambo university, ethiopia 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