98 Annales Universitatis Paedagogicae Cracoviensis Studia Naturae, 3 (supplement): 98–105, 2018, ISSN 2543-8832 DOI: 10.24917/25438832.3supp.13 Thiep Vo Van1,2*, Łukasz J. Binkowski1, Robert Stawarz1 1Institute of Biology, Pedagogical University of Cracow, Podchorazych 2, 30-084 Kraków, Poland 2Faculty of Agriculture, Forestry and Fisheries, Quang Binh University, 312 Ly �uong Kiet Str, Dong Hoi, Quang Binh, Vietnam, *thiep.vo-van@up.krakow.pl The concentration of mercury in organs of Whipfin silver biddy (Gerres filamentosus Cuv.) and Flathead grey mullet (Mugil cephalus L.) in coastal central Vietnam Introduction Vietnam is a part of South East Asia bordered by the ocean on the west east and the south, with China to the north and Cambodia and Laos to the west. �e coastline stretches over 3.260 km, with an exclusive economic zone (EEZ) of over 1 million km2 where is a habitat of a vast array of aquatic species (US Department of State, 1983; Pham, Masahide, 2007; Teh et al., 2014). Currently, with the increase in population, urbanization, industrialization, and agricultural practices, pollution with heavy met- als in an aquatic ecosystem may occur (Gupta et al., 2009). Mercury (Hg) is one of the most toxic metals in the aquatic ecosystems, which originates both from natural sources and human activities (Luciana et al., 2005; Seyed et al., 2013). Hg cannot be degraded; it is deposited in the aquatic sediments and can be bioaccumulated and biomagni�ed via the food chain, and �nally assimilated by human consumers, which results in health risks (Grimanis et al., 1978; Adams et al., 1992; Ermosele et al., 1995; Smith et al., 1996; Zweig et al., 1999; Agah et al., 2009; Malik et al., 2010). It is well known that �sh play an important role in the human diet. Fish is not only a source of proteins and healthy fats, but it is also a unique source of essential nutrients, including long-chain omega-3 fatty acids, iodine, vitamin D, and calcium (FDA, 2006; Kruzikova et al., 2013; Vicarova et al., 2015). However, it can represent a dangerous source of some heavy metals, especially Hg (Kruzikova et al., 2013). According to Stankovic et al. (2014), microbes, fungi, plants, animals, and humans are used as bioindicators of heavy metals (including Hg) originating from the air, wa- ter, sediment, soil, and the food web. �erefore, �sh could be a good and e�ective indicator of these elements in the aquatic environment. Fish represent a speci�c level 99 The concentration of m ercury in organs of W hipfin silver biddy (G erres filam entosus C uv.) and Flathead grey m ullet (M ugil cephalus L.) in coastal central V ietnam of the trophic pyramid and links Hg to the ecosystem by bioaccumulation and bio- magni�cation (Stankovic et al., 2014; Łuczyńska et al., 2016) In this study, two �sh species were collected: Whip�n silver biddy and Flathead grey mullet. �ese species are abundant and an easily accessible resources for arti- sanal �shing communities and are popular on Vietnam �sh markets. �ere is some published literature on Hg content of these two species in the world (Legorburu et al., 1988; Meng-Hsien Chen, 2002; Yilmaz, 2003; 2005; Chouba et al., 2007; Sih-Wei Huang et al., 2008; Frías-Espericueta et al., 2016; Türkmen et al., 2016; Ruelas-Inzunza et al., 2017; Delgado-Alvarez et al., 2017; Dung et al., 2018), but the data for Vietnam is scarce. �erefore, the aim of this study was to determine the e�ect of �sh species on Hg concentrations in the selected organs (muscle, liver, and gills) of Whip�n silver biddy and Flathead grey mullet. �e data obtained were used to access the level of risk asso- ciated with consumption two these �sh species in Vietnam. Moreover, the study also evaluates di�erences between the content of Hg in organs of the same �sh. Material and methods During July, August, and September 2017, �sh samples were obtained from local �sh- ermen and the �sh market of coastal Vietnam of Nghe An, Ha Tinh, Quang Binh, Quang Tri and Hue. Two �sh species were collected as Whip�n silver biddy – Gerres �lamentosus Cuv. (n = 28) and Flathead grey mullet – Mugil cephalus L. (n = 48). �e muscle tissue from the dorsal area, the liver, and gill tissue were collected, placed in labelled polypropylene bags and stored at -20°C until analysis. Total mercury concentrations in samples were determined by cold vapour atomic absorption spectrometry (NIC, MA-2; limit of quanti�cation was 0.2 ng per sample). Data was presented in µg g-1 wet weight. �e one-way analysis of variance ANOVA and Duncan’s test was used to test sig- ni�cant interspeci�c di�erences in the content of mercury both between species and the organs of the same species. Statistical signi�cance was declared when the p value was equal to or less than 0.05. Results and discussion �e highest Hg concentrations in Flathead grey mullet were found in the liver, fol- lowed by muscle and gills (0.195, 0.097 and 0.046 µg g-1 w.w., respectively – Tab.1). Th ie p V o V an , Ł uk as z J. B in ko w sk i, R ob er t S ta w ar z 100 Tab. 1. Mercury concentrations (µg g-1 wet weight) in gills, liver, and muscle of Flathead grey mullet (n = 48) Tissue Mean ±SD Min Max Gills 0.046 0.016 0.015 0.075 Liver 0.195 0.101 0.063 0.494 Muscle 0.097 0.037 0.027 0.184 Note: SD – standard deviation, Min – minimum, Max – maximum �ere are several studies of Hg concentrations of Flathead grey mullet available in the literature. Mostly, the concentrations reported are lower than the mean val- ue found in this study (Sankar et al., 2006; Dural et al., 2007; Ruelas-Inzunza et al., 2008; Sih-Wei Huang et al., 2008; Squadrone et al., 2013; Ruelas-Inzunza et al., 2017). However, there were also some reported Hg concentration higher than the mean we obtained (Chouba et al., 2007; Frías-Espericueta et al., 2016) (Tab. 2). Tab. 2. Mean total Hg concentrations (µg g-1 wet weight) in Flathead grey mullet Mean Hg concentration Location References Gills Liver Muscle 0.046 0.195 0.097 Central Vietnam �is study - 0.050 0.032 California US State Ruelas-Inzunza et al. (2017) - 0.503 0.036 Northwestern Mexico Frías-Espericueta et al. (2016) - - < 0.025 Mediterranean sea Squadrone et al. (2013) - - 0.016 Northwestern Mexico Ruelas-Inzunza et al. (2008) - 0.044 0.110 Tainan, Taiwan Sih-Wei Huang et al. (2008) - - 0.025 Mediterranean sea Dural et al. (2007) - 0.242 0.098 Tunisian lagoon (Winter) Chouba et al. (2007) - 0.235 0.084 Tunisian lagoon (Spring) Chouba et al. (2007) - 0.231 0.056 Tunisian lagoon (Summer) Chouba et al. (2007) - 0.247 0.102 Tunisian lagoon (Autumn) Chouba et al. (2007) - - 0.040 Calicut, India Sankar et al. (2006) Tab. 3. Mercury concentrations (µg g-1 wet weight) in gills, liver, and muscle of Whip�n silver biddy (n = 28) Tissue Mean ±SD Min Max Gills 0.077 0.040 0.036 0.220 Liver 0.245 0.187 0.078 0.643 Muscle 0.460 0.200 0.233 1.095 Note: SD – standard deviation, Min – minimum, Max – maximum Concentrations of Hg in gills, liver, and the muscle of Whip�n silver biddy di�ered between themselves (Tab. 3). �e highest mean was noted in muscles (0.460 µg g-1 w.w), followed by the liver and gills (0.245 and 0.077 µg g-1 w.w, respectively). In this study, Hg accumulation in muscles and the liver was higher than previously reported 101 by Meng-Hsien Chen (2002), Sih-Wei Huang et al. (2008), and Dung Le Quang et al. (2018). According to Meng-Hsien Chen (2002), Hg concentrations in muscles and livers of Whip�n silver biddy were both 0.025 µg g-1 w.w..In muscles, Sih-Wei Huang (2008) recorded 0.45 µg g-1 w.w., and Dung Le Quang (2018) recorded 0.358 µg g-1 w.w. �ere were signi�cant di�erences in mercury contents in muscles and gills be- tween both species in this study (p<0.05). However, there was no di�erence in the concentration of Hg in livers between Flathead grey mullet and Whip�n silver biddy (Tab. 4). Tab. 4. Di�erences in Hg concentration (µg g-1 wet weight) between the organs of both species Tissue Species Mean Statistical results (p) ±SD Min Max Gills Whip�n silver biddy 0.077 0.000 0.040 0.036 0.220 Flathead grey mullet 0.046 0.016 0.015 0.075 Liver Whip�n silver biddy 0.245 0.132 0.200 0.233 1.095 Flathead grey mullet 0.195 0.037 0.027 0.184 Muscle Whip�n silver biddy 0.460 0.000 0.187 0.078 0.643 Flathead grey mullet 0.097 0.101 0.063 0.494 Note: SD – standard deviation, Min – minimum, Max – maximum �e mean Hg concentrations determined in this study for Flathead grey mullet are one order of magnitude lower than the maximum permissible threshold (0.5 μg/g w.w. = 2 μg/g d.w.; FAO-WHO, 2003; Ministry of Health of Vietnam, 2007), which suggests wide limits of safety for the consumption of these �sh species. It is not the same in the case of Whip�n silver biddy, because the Hg concentration (0.460 µg g-1 w.w) in the muscle of this species almost reached the maximum permissible level. �e result of this study agree with the views of Türkmen et al. (2011; 2016) and Azevedo et al. (2012), which describe that, in most �sh species, the liver is the main storage place for metals. However, this is not a general rule in the case of Hg. We detected higher content of Hg in muscle than in liver in Whip�n silver biddy, as did Coelho et al. (2010) and Polack-Juszczak (2015). Additionally, Waltham et al. (2013) and Diop and Amara (2016) found no di�erences between Hg concentrations in livers and muscles of some �sh species. �e di�erence in Hg concentration in organs of �sh between the two species may be explained by several factors, such as resident time, trophic transfer, growth rate, prey type, and dietary quality. All of them can a�ect the Hg bioaccumulation in �sh communities (Hall et al., 1997; Marugo-Negrete et al., 2008). Among others factors, feeding habits have been recognised as a prime reason for Hg contamination (Hall et al., 1997). The concentration of m ercury in organs of W hipfin silver biddy (G erres filam entosus C uv.) and Flathead grey m ullet (M ugil cephalus L.) in coastal central V ietnam Th ie p V o V an , Ł uk as z J. B in ko w sk i, R ob er t S ta w ar z 102 Conclusions Statistically signi�cant di�erences in mean Hg levels were observed between two �sh species investigated (Whip�n silver biddy – Gerres �lamentosus Cuv. and Flathead grey mullet – Mugil cephalus L.) and their tissues, (except for their livers, there is no statistical di�erence between the two observed species). �ese results supply informa- tion on Hg contents in tissues of the species examined in coast central Vietnam and indirectly indicate Hg levels in the marine environment. �ese results can be used to understand the chemical quality of �sh and to evaluate the possible risk associated with their consumption. References Adams, W.J., Kimerle, R.A., Barnett, J.W. (1992). Sediment quality and aquatic life assessment. Environ- mental Science and Technology, 26, 1865–1875. Agah, H., Leermakers, M., Elskens, M., Fatemi, S.M.R., Baeyens, W. (2009). 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Di�er- ences in the total Hg were found both between two species and organs. �e concentration of Hg in all organs investigated of Whip�n silver biddy was higher than of Flathead grey mullet (p < 0.05). �e content of Hg in the muscles of Whip�n silver biddy was higher than in the livers and gills (p < 0.05), 0.460, 0.245, 0.077 µg g-1 w.w., respectively. Livers of Flathead grey mullet had more Hg accumulated than did the muscles and gills (0.195, 0.097, 0.046 µg g-1 w.w., respectively). �e results revealed that Hg concentrations in Flathead grey mullet did not exceed food �sh safety limits established for human consumption, while the concentration of this toxic element in the muscles of Whipin silver biddy almost reached the maximum permissible level. Keywords: Coastal Vietnam, Gerres �lamentosus, Mugil cephalus, mercury Received: [2018.05.28] Accepted: [2018.11.20] Stężenia rtęci w organach pobranych od Gerres filamentosus (Cuv.) i Mugil cephalus (L.) z Wietnamu Streszczenie Akumulacja rtęci (Hg) w rybach ma (duże, choć pośrednie) bezpośrednie znaczenie dla zdrowia ludzi i eko- systemu. Dlatego w tym projekcie zbadano stężenia Hg w skrzelach, wątrobie i mięśniach dwóch gatunków ryb (Gerres �lamentosus i Mugil cephalus). Badania przeprowadzono z wykorzystaniem techniki atomowej spektrometrii absorpcyjnej z przystawką zimnych par. Osobniki ryb zostały (kupione) pozyskane na lo- kalnych targach lub bezpośrednio od rybaków w okresie między lipcem a wrześniem 2017 r. w Wietnamie. Różnice w stężeniach rtęci były obserwowane zarówno między badanymi gatunkami, jak i tkankami (mate- riałami). Stężenia Hg wykryte we wszystkich materiałach pobranych od Gerres �lamentosus były wyższe niż w materiałach pobranych od Mugil cephalus (p < 0,05). Stężenia Hg w mięśniach Gerres �lamentosus były wyższe niż w wątrobie i skrzelach (p < 0,05), odpowiednio 0,460, 0,245 i 0,077 µg g-1 m.m. (mokrej masy). Wątroba Mugil cephalus zakumulowała wyższe stężenia Hg niż mięśnie i skrzela (odpowiednio 0,195; 0,097 i 0,046 µg g-1 m.m. Wyniki wskazują, że stężenia rtęci u Mugil cephalus (badanych gatunków) nie prze- kraczają norm ustalonych dla żywności do spożycia przez ludzi. Jednak poziom Hg w mięśniach Gerras �lamentosus jest zbliżony do tej wartości, co stanowi pewne zagrożenie dla potencjalnych konsunentów. Słowa kluczowe: Wietnam, Gerres �lamentosus, Mugil cephalus, rtęć Information on the authors �iep Vo Van He is mostly interested in �sh biology and �sh toxicology. Łukasz J. Binkowski https://orcid.org/0000-0001-7271-2371 He is specialised in the ecotoxicology and biomonitoring of metals in the environment and animals. Robert Stawarz https://orcid.org/0000-0002-0495-1730 His main scienti�c interests are dedicated to toxicology and physiology. The concentration of m ercury in organs of W hipfin silver biddy (G erres filam entosus C uv.) and Flathead grey m ullet (M ugil cephalus L.) in coastal central V ietnam