Concentrations In Fish Species Research Articles

Toxicity risks associated with heavy metals to fish species in the Transboundary River – Linked Ramsar Conservation Site of Tanguar Haor, Bangladesh

The presence of trace metals in aquatic ecosystems can have detrimental effects on fish survival. The Tanguar haor, a Ramsar conservation wetland, receives sediment and water from multiple transboundary rivers. However, there have been limited studies on the metal concentrations in fish species in this sediment-rich wetland. This study aimed to analyze the concentrations of iron (Fe), manganese (Mn), chromium (Cr), copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) in water, sediment, and fish tissues. Higher concentrations of Cd and Pb were found in the water and sediment. All these metals were detected in eight fish species, including benthic and pelagic species. Among them, Systomus sarana, a pelagic fish that also consumes benthic organisms, exhibited a higher metal pollution index than other fish, particularly benthic species. The release of higher metal concentrations from sediment into the water has the potential to impact the accumulation of metals in fish. SynopsisThis study on metal concentrations in fish species will aid policymaking on ecotoxicology research for transboundary river-connected wetlands.

Comprehensive GIS based risk surveillance of organochlorine pesticides (OCPs) in edible fish species of River Chenab, Pakistan

The present study was conducted to evaluate Carcinogenic (TR) and non-carcinogenic (THQ) human health risk of organochlorine pesticides (OCPs) in three edible fish species (Labeo boga, Channa marulius and Wallago attu) of River Chenab, Pakistan using USEPA human health risk assessment model. Holistic GIS (Geographic information system) based Geo-Statistical approach has been employed for the first time in River Chenab, Pakistan to categorize contaminated risk zones of OCPs based on single pollution index. The ∑OCPs concentrations in fish species were ranged from 5.09 to 414 ng/g with the prevalence of dieldrin. Results of single pollution index of DDE, aldrin, dieldrin and ∑endosulfan revealed River Chenab as polluted and risk zone area. Distribution pattern assessed significantly higher (p < 0.05) concentrations of OCPs in downstream area suggesting substantial pollution of surrounded industrial region. The human health risk assessment depicted no harmful non-carcinogenic (THQ) risk except for ΣOCPs concentration of C. marulius. Significant carcinogenic (TR) health risk exhibited by all examined OCPs from maximum of the studied sites. Therefore, the high carcinogenic human health risk had highlighted an immediate removal of continuous disposal of OCPs in the River Chenab.

Health risk assessment of exposure to heavy metals in fish species consumed in Aba, Abia State, Nigeria

Abstract The concentrations of heavy metals (Pb, As, Cr, Cu, Cd and Fe) were determined in the gills, liver and muscles of thirty-five fishes, water and sediment samples from Aba River using atomic absorption spectrophotometer. Heavy metal concentrations varied markedly among fish species and organs. Results revealed that Pb, Cr, Fe had maximum concentration levels of 0.63±0.01, 0.81±0.01 and 16.91 ± 0.20 mg/kg in Chrysichthys nigrodigitatus respectively. As and Cd recorded the highest concentration of 0.18±0.03 and 0.87±0.02 mg/kg in Malapterurus electricus respectively, while Trachurus trachurus had 1.05±0.03 mg/kg of Cu. Orenchromis niloticus, Tilapia ziili and Malapterurus electricus had higher concentrations of As and Cr in the liver compared to gills and muscles. The gills had higher concentrations of these heavy metals than liver and muscles in the rest of fish species studied. The concentrations of Cd, Pb and As in freshwater samples were higher than the standard maximum permissible limit. The sediments had higher concentrations of these metals than in fish and water samples. Heavy metal concentrations in fish species exceeded the standard guideline limit in food substances for human consumption. Malapterurus electricus, Parachanna obscura and Chrysichthys nigrodigitatus had bioaccumulation factors for Cd which ranged from 1.069-1.663, indicating potential Cd poisoning or contamination of the three fish species. The estimated daily intake in both adult and children ranged from 8.611 x 10−7 to 9.72 x 10−3 mg/kgbw/day and were within the standard limit of daily intake for the human population. The hazard quotient for adult and children populations ranged from 0.0041-1.3972 and 0.000287 - 0.2080 respectively. The hazard quotient was less than one in most of the metals except for iron, but hazard index was greater than one, indicating potential chronic health hazards. Incremental life cancer risk for the adult population was within safe limits.

Potential toxic elements in sediment and fishes of an important fish breeding river in Bangladesh: a preliminary study for ecological and health risks assessment

Indexical appraisal of potentially toxic elements (PTEs) in sediment and fish of riverine ecosystem give valuable information for environmental management. In this research, PTEs were measured in sediment and soft tissues of six fish species from an important fish breeding river (Halda) of Bangladesh to assess sediment quality and human health risks. The abundance of PTEs in sediments varied in the decreasing order of Fe > K > Ca > Ti > Zr > Sr > Rb > Mn > Zn > Cu > Ni > Pb > Co. The ranges of mean PTEs concentrations in fish species were as follows: Ca, 138.54–366.68; Cr, 8.86–11.34; Mn, 6.20–7.44; Fe, 52.98–871; Co, 2.0–3.06; Cu, 17.82–26.45; Zn, 48.27–115.75; Se, 5.16–6.79; Sr, 35.56–69.57; Hg, 0.42–2.15, and Pb, 0.26–0.64 mg/kg. The outcomes of the enrichment factor, geo-accumulation index, and contamination factor of PTEs in sediments varied spatially and most of the sediment samples were moderately polluted by PTEs. Biota-sediment accumulation factor indicated that Zn, Cu, and Co were more concentrated in fish species than other elements. Target hazard quotient (THQ) for the individual element was below 1, suggesting that people would not experience significant health hazards if they ingest a single metal from fish species.

Bioaccumulation of heavy metals in fish species of Iran: a review.

Accumulation of heavy metals (HMs) in fish tissues is an important factor in monitoring the health and safety of aquatic ecosystems. Furthermore, fish are important parts of aquatic food chains and play a significant role in human health. Considering the significant role of fish in the diet of humans and their ability to transfer and biomagnify HMs, it is necessary to determine and study these contaminants in fish tissues, especially in the edible parts of the fish. In addition to the other ecological and economic services of aquatic ecosystems, water bodies, especially the Persian Gulf in the south and the Caspian Sea in the north of Iran, are the main sources of seafood for people in nearby areas, as well as people living farther away who have gained access to seafood due to the extensive trade of aquatic organisms. This study provides an overview of the health conditions of the aquatic ecosystems in Iran by monitoring HM bioaccumulation in fish species. For this purpose, we reviewed, summarized, and evaluated papers published on HM concentrations in fish species from different aquatic ecosystems, including the Persian Gulf, the Caspian Sea, wetlands, rivers, qanats, water reservoirs, lakes, and dams, with emphasis on species habitats, feeding habits, and target organs in accumulation of HMs. Generally, the highest concentrations of HMs were observed in fishes collected from the Persian Gulf, followed by species from the Caspian Sea. Species inhabiting the lower zone of the water column and carnivorous and/or omnivorous species showed the highest levels of HMs. Moreover, liver was the main accumulator organ for HMs.

Comparative seasonal assessment of pollution and health risks associated with heavy metals in water, sediment and Fish of Buriganga and Turag River in Dhaka City, Bangladesh

Heavy-metal pollution of surface water, sediment and fish have been seen as a major global problem, with a significant proportion of developing countries like Bangladesh. This study assessed the intensity of alarming six toxic substances (Cr, Zn, Fe, Cu, Pb and Ni) throughout the River water, sediments as well as soft tissues of three widely consumed fishes (Heteropneustes fossilis, Channa punctatus and Channa striata) obtained from two urban streams of the Buriganga and Turag in the Dhaka metropolitan. For evaluating the comparative seasonal variation of heavy-metal concentration, water and sediment samples were collected from five selected sites for two different seasons (viz. 10 from winter seasons and 10 from summer seasons). Finally, a total of 20 water samples, 20 sediment and 12 fish samples were investigated by flame atomic absorption spectroscopy (FAAS) and graphite furnace atomic absorption spectrometer (GFAAS) corrected with the Zeeman effect background correction system. The hierarchy of mean concentration of selected heavy metals in Buriganga water is found to be Fe > Cr > Ni > Zn > Cu > Pb in the winter season whereas during the summer season the order is Fe > Cr > Zn > Ni > Cu > Pb. For the River Turag, the order is Fe > Zn > Cu > Ni > Cr > Pb and Fe > Zn > Ni > Cu > Cr > Pb during winter and summer season, respectively. The level of metals studied surpassed the acceptable level of drinkable water, implying the ineptitude of drinking and cooking water from these Rivers. However, this hierarchy of heavy metals for sediments of Buriganga River changed to Fe > Cr > Ni > Zn > Cu > Pb for the winter season and Fe > Cr > Ni > Cu > Zn > Pb for the summer season. Whereas, for the Turag River, the decreasing trend of metal concentration found in sediment was Fe > Zn > Cr > Ni > Cu > Pb for both seasons. For probable human health hazard implications, contamination factor (CF) and pollution load index (PLI) were studied. The CF values revealed the low-to-moderate pollution of sediment. The PLI value above one shows the degradation of the consistency of the sediments. Fe, Ni, Pb, Cr, Zn and Cu concentrations in fish species were found to be 19.66–45.1, 0.07–12.18, 1.2–10.18, 20.18–187.07, 11.08–68.25, 2.07–10.4 mg/kg, respectively. The metals studied differed considerably among organisms and seasons. Bioconcentration factor (BCF), the daily average consumption of metal (EDI), as well as target threat quotients (THQs) for specific metal indicated that Cr and Pb are harmful in fish muscles and possible risks remain for fish consumers. The obtained concentrations of some metals are higher than the WHO/FAO’s permissible limit, suggesting that the water and fish found in these Rivers are like to be harmful to the human being. This study shows that attention should be given to the risk assessment for heavy metals in these Rivers.

Research Article: Organophosphorus pesticides (diazinon, malathion and azinfos methyl) accumulation in three fish species, in south coasts of the Caspian Sea, Iran

In this study the distribution and accumulation of diazinon, malathion and azinfos methyl in mullet Liza aurata,Caspian white fish Rutilus kutum and common carp Cyprinus carpio from five estuaries along the Caspian Sea have been investigated. Also, the effects of pesticides concentrations on the acetylcholinesterase enzyme (AChE) in fish species were studies. Pesticides concentration varied with fish species, sampling station and toxins types. The results indicate that the pesticides concentrations varied from 0.01 to 0.16 mg kg-1 for diazinon, 0.01 to 0.15 mg kg-1 for malathion and 0.05 to 0.36 mg kg-1 for azinfos methyl in three fish species. There was significant difference between different toxins concentrations in fish species, (p diazinon>malathion. There was significant difference in toxins concentrations between three fish species, and the highest toxins concentrations were absorbed in detritivores fish (L. aurata), followed by herbivorous fish (C. carpio) and carnivore fish (R. kutum). The results confirmed that toxins bioaccumulation in fish species is strongly controlled by habitat and feeding habits.

Toxic and essential trace element concentrations in fish species in the Lower Amazon, Brazil

The Lower Amazon region (Western Pará, northern Brazil) is greatly affected by mining exploitations (particularly artisanal gold mines) and other industrial and intensive agricultural activities with potentially strong impacts on aquatic ecosystems. Although such impacts include contamination with various toxic elements, to date only the effects of Hg have been considered. In this study, toxic and trace element concentrations were determined in the flesh of 351 fish specimens, including detritivores (Acarí, Pterygoplichthys pardalis), omnivores (Piranha, Pygocentrus nattereri; Pirarucu, Arapaima sp.) and carnivores (Caparari, Pseudoplatystoma fasciatum; Tucunaré, Cichla ocellaris), during the dry and wet seasons in 2015 and 2016. The range of concentrations of toxic element residues were 2–238 μg/kg fresh weight for As, 1–77 μg/kg for Cd, 4–1922 μg/kg for Hg and 1–30 μg/kg for Pb. Only the maximum concentrations of Hg established in the Brazilian legislation for fish destined for human consumption (0.5 mg/kg) were exceeded (in 16% of carnivorous species). The large between-species and seasonal differences observed for all these toxic elements are probably related to the seasonal behaviour and dietary habits of the different fish species. By contrast, essential trace element concentrations were low and not related to seasonal or dietary factors, and the observed differences may be at least partly related to the metabolism of each species. The associations between Hg and the essential trace elements Se, Fe, Co and Mn deserve special attention, as these trace elements may play a role in Hg cycling and methylation and merit further evaluation with the aim of reducing Hg toxicity in aquatic environments.

Ecological drivers of mercury concentrations in fish species in subsistence harvests from Kotzebue Sound, Alaska

The State of Alaska assesses human exposure to mercury (Hg) via fish consumption producing consumption guidelines for fish tailored for children and women of childbearing age. Under these guidelines, unrestricted consumption is suggested for many fish species, while limited consumption is recommended for others. Subsequent questions have arisen regarding ecological drivers influencing [Hg] in fishes consumed by Alaskans. This community-assisted public health study evaluates [Hg] in fishes from Kotzebue Sound to examine factors that may drive observed [Hg]. We examined eight species of subsistence harvested fish (least cisco, chum salmon, Pacific herring, humpback whitefish, sheefish, starry flounder, Pacific tomcod, and fourhorn sculpin) from Kotzebue Sound. We report total Hg concentrations ([THg]) and monomethyl Hg+ concentrations ([MeHg+]) in the context of various factors (such as species, fork length, carbon and nitrogen stable isotope (δ15N or δ13C)) values that may influence [Hg] and [MeHg+]. Across all 297 fish, [THg] ranged from 3.4 ˗ 235.2 ng/g ww. [THg] was positively correlated with fork length in six of eight fish species, as well as with trophic level (indicated by δ15N values) in five species. [MeHg+] was positively correlated with fork length in four species, and with δ15N values over all specimens examined, and specifically for three individual species. In six of the seven species analyzed, %MeHg was >80% of [THg]. This value decreased with fork length in three species, with no relationship for δ15N values in any species. Among top ranked models based on Akaike Information Criterion correction (AICc), fork length was more frequently included as an explanatory factor for [Hg] than δ15N or δ13C values. The food web magnification factor for [THg] was 11.3, and 12.6 for [MeHg+]. Biomagnification is likely driving [THg] and [MeHg+] over the entire food web, while within species, bioaccumulation is likely a stronger driver of [THg] and [MeHg+] than feeding ecology or trophic position. The [THg] for all species fell within the established unrestricted consumption guideline of 200 ng/g weight wet as established by the State of Alaska's fish consumption guidelines for Hg.

Occurrence of organochlorine pesticides and polychlorinated biphenyls in sediment and fish in Cau Hai lagoon of Central Vietnam: Human health risk assessment

This is the first study on polychlorinated biphenyls (PCBs) in fish from the Cau Hai lagoon, a part of the largest coastal lagoon in Southeast Asia. Seven selected PCB congeners and organochlorine pesticides in sediments and edible fish tissues were quantified by GC–MS. The sum of ICES-7 PCB and DDTs concentrations in fish species consumed regularly and of economic value were in ranges 26–43 ng g−1 lw and 182–277 ng g−1 lw, respectively. The ratio between the parent DDT compound and the sum of metabolites, DDE and DDD, was most of the time smaller than 1, suggesting primarily an historical contamination of the lagoon. An agglomerative hierarchical clustering indicates sites located in the north-western part of the Cau Hai lagoon were characterized by above-average concentrations of DDE and DDT. Comparing to previous data, a large decrease in ∑DDT residues can be seen over the past 20 years.

Mercury and selenium in fishes from the Tapajós River in the Brazilian Amazon: An evaluation of human exposure

This work aimed to evaluate associated risks of fish consumption to human health, concerning mercury (Hg) and selenium (Se) concentrations in fish species largely consumed in the Tapajós River basin in the Brazilian Amazon. Total mercury (THg), methylmercury (MeHg) and Se concentrations were measured in 129 fish specimens from four sites of the Tapajós River basin. Estimated daily intake (EDI) of Hg and Se were reported regarding fish consumption. EDI were compared with the reference value of provisional tolerable daily intake proposed by the World Health Organization (WHO). Se:Hg ratios and selenium health benefit values (Se HBVs) seem to offer a more comprehensive fish safety model. THg concentrations in fishes ranged from 0.03 to 1.51 μg g−1 of wet weight (w.w.) and MeHg concentrations ranged from 0.02 to 1.44 μg g−1 (w.w.). 80% of the samples were below the value of Hg recommended by the WHO for human consumption (0.5 μg g−1 w.w.). However, Hg EDI exceeded the dose suggested by the United States Environmental Protection Agency (0.1 μg kg−1 day−1), due to the large level of fish consumption in that area. Se concentrations in fishes ranged from 0.02 to 0.44 μg g−1 w.w. An inverse pattern was observed between Hg and Se concentrations in the trophic chain (highest levels of Se in the lowest trophic levels). The molar ratio Se:Hg and Se HBVs were higher in iliophagous and herbivorous fishes, which is noteworthy to reduce toxic effects of Hg contamination. For planktivores, the content of Se and Hg was almost equimolar. Carnivorous fishes – with the exception of Hemisorubim platyrhynchos and Pseudoplatystoma fasciatum –, showed Se:Hg ratios <1. Thus, they do not act as a favorable source of Se in the diet. Therefore, reduced intake of carnivorous fishes with preferential consumption of iliophages, herbivores and, to some extent, even planktivores should be promoted as part of a healthier diet.

Heavy metals in sediment and their accumulation in commonly consumed fish species in Bangladesh

ABSTRACTSix heavy metals (chromium [Cr], nickel [Ni], copper [Cu], arsenic [As], cadmium [Cd], and lead [Pb]) were measured in sediments and soft tissues of eleven commonly consumed fish species collected from an urban river in the northern part of Bangladesh. The abundance of heavy metals in sediments varied in the decreasing order of Cr > Ni > Cu > Pb > As > Cd. The ranges of mean metal concentrations in fish species, in mg/kg wet weight (ww), were as follows: Cr, 0.11–0.46; Ni, 0.77–2.6; Cu, 0.57–2.1; As, 0.43–1.7; Cd, 0.020–0.23; and Pb, 0.15–1.1. Target hazard quotients (THQs) and target carcinogenic risk (TR) showed the intake of As and Pb through fish consumption were higher than the recommended values, indicating the consumption of these fish species is associated with noncarcinogenic and carcinogenic health risks.

Heavy Metal Concentrations in Fish Species from Three Gorges Reservoir, China, After Impoundment.

The concentrations of Pb, Cr, Cd, As, and Hg were analyzed in the muscles of eleven fish species collected from the Wanzhou section of the Three Gorges Reservoir, Yangtze River, China. The results showed that the concentrations of Pb, Cr, Cd, As, and Hg in the muscles of all of the fish species were lower than the proposed limits. The metal concentrations (Pb, Cr, Cd, and As) of pelagic fish species were found to be substantially lower than those in benthic fish species. The concentrations of Hg in carnivorous fish were higher than those in omnivorous fish. Compared with data obtained prior to the impoundment of the Three Gorges Reservoir, the concentration of Hg in the fish did not significantly increase after impoundment, while the concentrations of Pb, Cr, Cd, and As in the fish decreased.

Mercury pollution in fish from South China Sea: Levels, species-specific accumulation, and possible sources

Both total mercury (THg) and methylmercury (MeHg) levels in fish collected from South China Sea (SCS) were studied to understand Hg pollution in Chinese tropical marine ecosystems. The average THg concentrations in fish species ranged from 39.6μg/kg for rabbitfish (Siganus fuscessens) to 417μg/kg for thornfish (Terapon jarbua), while those of MeHg varied from 13μg/kg (rabbitfish) to 176μg/kg (thornfish). The median values of MeHg/THg ratios in different fish species ranged from 36 to 85%. Significant inter-species differences of THg and MeHg in fish were observed due to feeding habits and fish sizes. Overall, carnivorous fish had higher levels of THg, MeHg and MeHg/THg ratios than omnivorous and herbivorous fish. High Hg levels in fish of the SCS were probably related to Hg input from atmospheric deposition and anthropogenic activities.

Mercury Levels in Barbadian Fisher Folk and Commonly Caught Fish Species

ABSTRACT Ocean fish are an important staple food for many Caribbean persons. Some species, however, have high Hg concentration levels and represent a significant source of Hg exposure. This study assessed Hg concentrations in fish species commonly caught and consumed in Barbados as well as Hg exposure of those who work in the fishing industry. Total Hg concentrations were measured in 100 fish samples. Human Hg concentrations were determined from hair snippets taken from 46 fisher folk and fish consumption habits evaluated using interview-administered questionnaires. Mercury levels varied by fish species with predatory fish species having the highest concentrations. Low Hg concentrations were found in dolphinfish (Coryphaena hippurus) and flyingfish (Hirundichthys affinis). Reported fish consumption rates were high and varied significantly between men and women, 2675 ± 1600 and 1275 ± 600 (g/week), respectively (p = 0.01). The median hair Hg concentration was 3.1 ± 2.3 μg/g (range: 0.01–15.6 μg/g) and significantly associated with consumption of “high-risk” fish species (p = .02). These results show that it is possible to make informed choices concerning fish consumption habits in order to maximize benefits while minimizing the effect of Hg exposures, especially for sensitive groups such as pregnant women and infants.

Comparison of Metal Accumulation in Fish Species from the Southeastern Black Sea

In this study, it was aimed to determine accumulation of the metal concentrations in fish species in different regions which are Sürmene and Yomra bay at southeastern Black sea in Trabzon-Turkey. For this purpose, concentrations of metals (Cr, Co, Ni, Cu, Zn, As, Se, Cd, Sb, Hg, Pb) were measured by inductively coupled plasma mass spectrometry (ICP-MS) in muscle of red mullet (Mullus barbatus ponticus) and whiting (Merlangius merlangus euxinus). Metal concentrations were found for whiting ranged as follows; 0.35-1.64 (Cr), 0.01-0.09 (Co), 0.01-0.71 (Ni), 0.71-1.45 (Cu), 18.64-68.06 (Zn), 2.05-9.66 (As), 0.15-14.16 (Se), 0.01-0.22 (Cd), 0.01-0.01 (Sb), 0.01-0.15 (Hg), 0.01-0.25 (Pb) and for red mullet as 0.43-1.04 (Cr), 0.05-0.23 (Co), 0.02-0.67 (Ni), 0.74-2.32 (Cu), 19.89-43.50 (Zn), 6.04-24.82 (As), 0.02-9.83 (Se), 0.01-0.11 (Cd), 0.01-0.01 (Sb), 0.07-0.18 (Hg), 0.01-0.20 (Pb) μg g(-1) dry weight. Metal concentrations in samples were found to be lower than legal limits proposed by Turkish Food Codex (2008), Food and Agricultural Organization (1983), and European Commission (Off J Eur Union L364-5-L364-24, 2006) for human consumption.

Biodynamic understanding of mercury accumulation in marine and freshwater fish

Mercury (Hg) is a global environmental pollutant that has been the cause of many public concerns. One particular concern about Hg in aquatic systems is its trophic transfer and biomagnification in food chains. For example, the Hg concentration increases with the increase of food chain level. Fish at the top of food chain can accumulate high concentrations of Hg (especially the toxic form, methylmercury, MeHg), which is then transferred to humans through seafood consumption. Various biological and physiochemical conditions can significantly affect the bioaccumulation of Hgincluding both its inorganic (Hg(II)) and organic (MeHg) formsin fish. There have been numerous measurements of Hg concentrations in marine and freshwater fish worldwide. Many of these studies have attempted to identify the processes leading to variations of Hg concentrations in fish species from different habitats. The development of a biokinetic model over the past decade has helped improve our understanding of the mechanisms underlying the bioaccumulation processes of Hg in aquatic animals. In this review, I will discuss how the biokinetic modeling approach can be used to reveal the interesting biodynamics of Hg in fish, such as the trophic transfer and exposure route of Hg(II) and MeHg, as well as growth enrichment (the increases in Hg concentration with fish size) and biomass dilution (the decreases in Hg concentration with increasing phytoplankton biomass). I will also discuss the relevance of studying the subcellular fates of Hg to predict the Hg bioaccessibility and detoxification in fish. Future challenges will be to understand the inter- and intra-species differences in Hg accumulation and the management/mitigation of Hg pollution in both marine and freshwater fish based on our knowledge of Hg biodynamics.

Biodynamic understanding of mercury accumulation in marine and freshwater fish

Mercury (Hg) is a global environmental pollutant that has been the cause of many public concerns. One particular concern about Hg in aquatic systems is its trophic transfer and biomagnification in food chains. For example, the Hg concentration increases with the increase of food chain level. Fish at the top of food chain can accumulate high concentrations of Hg (especially the toxic form, methylmercury, MeHg), which is then transferred to humans through seafood consumption. Various biological and physiochemical conditions can significantly affect the bioaccumulation of Hgincluding both its inorganic (Hg(II)) and organic (MeHg) formsin fish. There have been numerous measurements of Hg concentrations in marine and freshwater fish worldwide. Many of these studies have attempted to identify the processes leading to variations of Hg concentrations in fish species from different habitats. The development of a biokinetic model over the past decade has helped improve our understanding of the mechanisms underlying the bioaccumulation processes of Hg in aquatic animals. In this review, I will discuss how the biokinetic modeling approach can be used to reveal the interesting biodynamics of Hg in fish, such as the trophic transfer and exposure route of Hg(II) and MeHg, as well as growth enrichment (the increases in Hg concentration with fish size) and biomass dilution (the decreases in Hg concentration with increasing phytoplankton biomass). I will also discuss the relevance of studying the subcellular fates of Hg to predict the Hg bioaccessibility and detoxification in fish. Future challenges will be to understand the inter- and intra-species differences in Hg accumulation and the management/mitigation of Hg pollution in both marine and freshwater fish based on our knowledge of Hg biodynamics.

Heavy metals and arsenic concentrations in ten fish species from the Šalek lakes (Slovenia): assessment of potential human health risk due to fish consumption

The study, which measured the concentrations of Hg, Pb, Cd, Zn and As in various fish tissues (muscle, gill and liver) of 10 fish species (Abramis brama danubii, Alburnus alburnus alburnus, Barbus meridionalis petenyi, Carassius auratius gibelio, Cyprinus carpio, Lepomis gibossus, Leuciscius cephalus cephalus, Perca fluviatilis fluviatilis, Rutilus rutilus, Scardinus erythrophtlalmus erythrophtlalmus) collected in the Šalek lakes, is the first survey regarding metal concentrations in fish species with samples originating from Slovene lakes, while only a limited number of such studies have been carried out in southeastern Europe. Since these lakes are situated in the close vicinity of the largest Slovene thermal power plant, the study provides an insight into the potential impact of increased levels of metals in the environment as well as an estimate of the contamination of fish tissues with metals. Furthermore, it was possible to compare the results obtained with those from other studies regarding metal levels in freshwater fish species. The mean metal concentrations of different tissues irrespective of species varied in the following ranges: Zn 4.31-199mg/kg ww, Pb 0.01-0.48mg/kg ww, As 0.02-0.44mg/kg ww, Hg <0.01-0.31mg/kg ww, Cd < 0.01-0.19mg/kg ww. In general, higher contents of Hg were found in muscles and livers than in gills and higher contents of As in gills and livers than in muscles, respectively. The accumulation of Pb and Zn was most pronounced in gills. The result obtained regarding metal concentrations in fish revealed that the ecosystems of the Šalek lakes are not polluted with Hg and Pb, slightly loaded with As and Cd and moderately polluted with Zn. In addition, the potential human health risk due to fish consumption was assessed. This showed that the estimated weekly intakes for all metals were far below provisional permissible tolerable weekly intakes determined by WHO/FAO. The consumption of fish from the Šalek lakes, therefore, does not pose a risk to human health.

Mercury concentrations in fish species caught at Mid-Atlantic Ridge hydrothermal vent fields

Concentrations of total mercury and methyl mercury were determined in muscle and liver samples of 8 fish species caught at the Menez Gwen, Lucky Strike and Rainbow hydrothermal vents (Mid-Atlantic Ridge). The species studied were Hydrolagus pallidus, H. affinis, Synapho- branchus kaupi, Epigonus telescopus, Mora moro, Antimora rostrata, Deania calceus and Etmopterus princeps. Median total mercury concentrations found in muscle tissue of the 8 species ranged between 0.6 and 1.9 µg g -1 wet weight and between 0.1 and 1.7 µg g -1 wet weight for liver tissue in 5 of the species. Differences in total mercury concentration in species caught at the different hydrothermal vents, comparisons between tissues and correlation with total length are described. In general, liver tissues present lower total mercury concentrations than muscle. Methyl mercury accu- mulated in fish from this study comprises, on average, >80% of the total mercury. The total mercury concentrations found were higher than those previously published for deep-sea fish. These fish spe- cies were exposed to high levels of mercury, due not only to bioavailability of toxic and stable forms of mercury in the water, but also to predation on organisms exposed to this metal.