






























*Corresponding author:
Email: drpnatarajan123@gmail.com, phone +251- 969-454307

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 g-

1.  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.  

 

 

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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 Monghit-
Camarin 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 

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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. 

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East Afr. J. Biophys. Comput. Sci., Vol. 1, Issue 1 
 

 

 

Table- 1: 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).  

Table- 2. 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 
 

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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 g-

1; 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 

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East Afr. J. Biophys. Comput. Sci., Vol. 1, Issue 1 
 

 

contaminated water and sediment in the aquatic 
media. 

 

Table- 3: 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. 

 
 
 
 

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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 

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East Afr. J. Biophys. Comput. Sci., Vol. 1, Issue 1 
 

 

Table- 6.  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.  

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	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...
	Table- 5: 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. Box- 05, 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

