Relation between growth and the heavy metal concentration in organs of bream Abramis brama L. populating Lake Balaton

Quantifying the bioaccumulation and trophic transfer processes of heavy metals based on the food web: A case study from freshwater wetland in northeast China

The contamination of wetlands by heavy metals, exacerbated by agricultural activities, presents a threat to both organisms and humans. Heavy metals may undergo trophic transfer through the food web. However, the methods for quantifying the bioaccumulation and trophic transfer processes of heavy metals based on the food web remains unclear. In this study, we employed stable isotope technology to construct a quantitative oriental white stork's typical food web model under a more accurate scaled Δ15N framework. On this basis, the concentrations for heavy metal (Cu, Zn, Hg, Pb) were analyzed, we innovatively visualized the trophic transfer process of heavy metals across 13 nodes and 45 links and quantified the transfer flux based on the diet proportions and heavy metal concentrations of species, taking into account biomagnification effects and potential risks. Our findings revealed that as for Cu and Pb, the transfer flux level was consistent with diet proportion across most links. While Hg and Zn transfer flux level exceeded the corresponding diet proportion in the majority of links. In summary, Hg exhibited a significant biomagnification, whereas Cu, Zn, Pb experienced biodilution. The fish dietary health risk assessment for fish consumers showed that Hg, Pb posed certain risks. This research marks a significant step forward in the quantitative assessment of multi-link networks involving heavy metals within the food web.

Trophodynamics and potential health risk assessment of heavy metals in the mangrove food web in Yanpu Bay, China

Mangroves are the cradle of coastal water biodiversity and are susceptible to heavy metal pollution. However, the trophic transfer mechanism of heavy metals in the mangrove food web and the resulting human health risks are not fully understood. Heavy metal concentration (Cr, Ni, Cu, Zn, As, Cd, Pb, V, Co) and stable isotope ratios of carbon and nitrogen (δ13C and δ15N) were evaluated in sediments and particulate organic matter, litter, and aquatic organisms (plankton, arthropods, mollusks, omnivorous fish, and carnivorous fish) from the Yanpu Bay mangroves. The results revealed that heavy metals exhibited different trophic transfer patterns. As and Hg were efficiently biomagnified, with trophic magnification factors of 1.17 and 1.42, respectively; while Cr, Ni, Cu, Cd, Pb, V, and Co were efficiently biodiluted. Zn exhibited a trophic magnification factor > 1 and was not significantly correlated with δ15N (p > 0.05), suggesting no biomagnification or biodilution. The heavy metals in the important fishery species (omnivorous fish and carnivorous fish) were below the permissible limits, except for Zn in Ophichthus apicalis. The assessment of probabilistic health risks revealed that fish consumption in adults and children posed an acceptable risk (total target hazard quotient <1).

Trophic transfer of heavy metals across four trophic levels based on muscle tissue residuals: a case study of Dachen Fishing Grounds, the East China Sea

In this study, we collected 56 species of fishery organisms (including fish, crustaceans, cephalopods, gastropods, and bivalves) from four seasonal survey cruises at the Dachen fishery grounds. We measured the concentrations of seven heavy metals (Cd, Zn, Cu, Pb, Cr, As, and Hg) in these fisheries organisms. We determined their trophic levels using carbon and nitrogen stable isotope techniques. We analyzed the characteristics of heavy metal transfer in the food chain. The results showed significant differences in heavy metal concentrations among different species. Among all biological groups, bivalves and gastropods exhibited higher levels of heavy metal enrichment than other biological groups, while fish had the lowest levels of heavy metal enrichment. Heavy metals exhibited different patterns of nutritional transfer in the food chain. While Hg showed a biomagnification phenomenon in the food chain, it was not significant. Cd, Zn, Cu, Pb, Cr, and As exhibited a trend of biodilution with increasing nutritional levels, except for As, which showed no significant correlation with δ15N.

Elemental composition of Talang Queenfish (Scomberoides commersonnianus Lacépède, 1801) in relation to body size and condition factor from Pakistan

Abstract Fish is thought to be the most appropriate for indication of toxicity in water. So, purpose of present study was to determine the concentrations of few metals (Na, K, Ca, Mg, Fe, Cd, Pb and Zn) in relation to the body size and condition factor in Scomberoides commersonnianus. A total of 73 samples of marine fish, S. commersonnianus with various sizes that ranged from 93.4-1180 g of body weight and total length 20.5-56.9cm were randomly collected from the Arabian Sea of Karachi Pakistan, for examination of elemental composition. The concentration of Calcium found maximum while Cadmium found minimum in S. commersonnianus. Concentrations of Zn showed highly significant (P<0.001) negative, while Na and Ca exhibited strong positive correlation with the fish size. Correlations of Pb, K and Mg were found least significant (P<0.05) with the wet weight and total length of S. commersonnianus. Whereas, Fe and Cd were remained insignificantly correlated (P>0.05) with the fish size. Condition factor showed highly significant correlation (P<0.001) with all studied metals except cadmium and lead which were found insignificantly correlated (P>0.05) with condition factor of S. commersonnianus.

Combined effects of high temperature and pesticide mixture exposure on free-swimming behaviors and hepatic cytochrome P450 1A expression in goldfish, Carassius auratus

The synergy between multiple compounds and other stressors, including heat, creates volatility and greater unpredictability than standard single-chemical toxicity testing, especially in the case of pesticides and metabolites which might contain several noxious ingredients resulting in adverse ecological effects. To address this, the aim of this study was to examine the dose- and time-dependent effects of low- and high-dose pesticide mixture (metalachlor, linuron, isoproturon, tebucanazole, aclonifen, atrazine, pendimethalin, azinphos-methyl) and heat stress co-exposure (22°C control/32°C treatment for 4-week) on free-swimming behaviors and cumulative actionless time (CAT) of goldfish. Behavioral analysis showed a dose- and time-dependent decrease in distance swam, as well as a subsequent increase in CAT. Vertical and horizontal spatial behavioral use were affected under heat and pesticides co-exposure conditions. In 3- and 4-week(s) exposure groups, horizontal spatial behavioral use demonstrated elevated time spent in the lower third of the aquarium. Similarly, during 3- and 4-week(s) exposure (32°C control and 32°C high doses) vertical spatial behavioral use was found to increase time spent in the outermost edges of the aquarium. In all treatment groups, the final condition factor (KM) showed significant attenuation when compared to the initial KM. However, there was an unclear relationship between heat/pesticide co-exposure and growth most notably in 32°C high-dose groups. In addition, the expression of hepatic cytochrome P450 1A mRNA was significantly higher in pesticide-exposed groups. Taken together, data demonstrated that co-exposure with low- or high-dose pesticide mixture and heat stress significantly impacted natural swimming patterns, which over time might result in the broader population and ecological effects.

Health risk assessment and metal contamination in fish, water and soil sediments in the East Kolkata Wetlands, India, Ramsar site

East Kolkata Wetlands (EKW) is an important site for fish culture in sewage-fed areas, which are major receivers of pollutants and wastages from Kolkata. EKW is internationally important as the Ramsar site was declared on Aug 2002 with an area of 125 km². EKW is a natural water body where wastewater-fed natural aquaculture has been practiced for more than 70 years. It is ecologically vulnerable due to the discharge of toxic waste through sewage canals from cities. Assessing the EKW to understand the inflow and load of the toxic metal (s) in fish, water, and sediments samples is essential. The field (samples collection from 13 sites) and lab (determination of toxic level of metals) based research were carried out to assess metal toxicity and health risk assessment in EKW. The levels of eighteen metals (18), namely Chromium, Vanadium, Cobalt, Manganese, Copper, Nickel, Zinc, Silver, Molybdenum, Arsenic, Selenium, Tin, Gallium, Germanium, Strontium, Cadmium, Mercury, and Lead, were determined using Inductively coupled plasma mass spectrometry (ICP-MS) in five fish tissues viz. muscle, liver, kidney, gill and brain, along with the water samples and soil sediments in 13 sampling sites. The bioaccumulation and concentration of metals in fish tissues, soil sediments, and water samples were well within the safe level concerning the recommendation of different national and international agencies except for a few metals in a few sampling sites like Cd, As, and Pb. The geoaccumulation index (Igeo) was also determined in the soil sediments, indicating moderate arsenic, selenium, and mercury contamination in a few sites. The contamination index in water was also determined in 13 sampling sites. The estimated daily intake (EDI), reference dose (RfD), target hazard quotient (THQ), slope factor and cancer risk of Cr, Mn, Co, Ni, Cu, Zn, As, Se, Cd, Pb and Hg from fish muscle were determined. Based on the results of the present investigation, it is concluded that fish consumption in the East Kolkata Wetland (EKW) is safe. The effects of bioaccumulation of metals in muscle tissue were well within the safe level for consumption as recommended by WHO/FAO.

Trophodynamics and health risk assessment of toxic trace metals in the food web of a plateau freshwater lake

The trophodynamics of toxic trace metals is significant for assessing the threat of toxic trace metals to the aquatic ecosystem and human safety. However, due to the difficulty of accurately calculating the trophic positions of freshwater aquatic organisms in the food web, the comprehensive process of trophodynamics of toxic trace metals in freshwater ecosystems was still rarely known. By integrating the compound-specific nitrogen stable isotopic analysis of amino acids (CSIA-AAs) and the Bayesian stable isotope mixing model (SIMM) as a novel approach, the present study investigated the trophodynamics of five toxic trace metals (Zn, As, Cr, Cu, and Hg) in the food web of the YangZong Lake, a plateau freshwater lake that was once heavily polluted by arsenic in Yunnan Province, China. The results revealed that Hg tended to be efficiently biomagnified in the food web with a trophic magnification factor of 1.75; As, Cr, and Cu were biodiluted significantly, while Zn showed no biomagnification or biodilution trends. The dietary health risk assessment indicated the potential health risk of toxic trace metals for the local residents of long-term fish consumption. The present work highlights the accuracy and reliability of the novel CSIA-AAS+SIMM approach in the calculation of the trophic positions of freshwater organisms.

Health Hazards of Toxic and Essential Heavy Metals from the Poultry Waste on Human and Aquatic Organisms

This research was conducted to examine the impact of some essential heavy metals used as a supplement during animal feed formulation and the toxic from unregulated discharges of untreated poultry waste into water bodies on man and aquatic organisms. During the processing of poultry feed, certain heavy metals are used as a supplement such as selenium, copper, zinc, iron etc. to enhance poultry meat and egg yield which is also increase the daily discharge of anthropogenic wastes into our environment that contain high concentration of heavy metals discharges into aquatic environment globally, especially in underdeveloped where this waste are not treated before discharge or used in agriculture as an organic fertilizer in planting crops as a result of this it become absorb by plants and could pose a serious health risk to man and aquatic species as well as affect the ecological balance that can be transfer to humans via the food chain. Some organisms are kills as a result of the toxic heavy metals in water and can affect their growths. Bio-accumulated in the body of certain species, such as fish, which are eaten by humans that causes devastating diseases such as Minamata and Itai-Itai. Regulation of the use some heavy metals as a supplement in feed production or complete removal of it in animal feed should be adopt in order to minimize the human health risks and environmental contamination associated with these animal waste.

Influence of sex and maturity state on trace elements content in liver and muscle of the Sciaenidae Totoaba macdonaldi

BACKGROUND

The fish Totoaba macdonaldi is endemic to the Upper Gulf of California. Its migratory movements involve sites with high levels of trace elements in the environment that can accumulate in tissues. In this study, lead (Pb), copper (Cu), cadmium (Cd), zinc (Zn) and iron (Fe) concentrations in male and female totoaba liver and muscle were quantified at various sexual maturity stages along the species' geographic distribution.

METHODS

Generalized linear models were used to explore associations between trace element concentrations and season of the year, sex/maturity stage, and total fish length.

RESULTS

No detectable Pb concentrations were recorded in liver or muscle; Cu, Cd, Zn and Fe contents in totoaba liver and muscle were typical of fish inhabiting areas with no contamination issues and are within international maximum permissible levels for human consumption. Variations in the content of Cd, Cu, Zn and Fe in liver of totoaba seem to be more related to the feeding and reproductive physiology of this species than as result of environmental exposure. Results suggest that consumption of totoaba muscle does not pose a public health risk. Furthermore, depending on the sex/maturity stage of totoaba, this fish's muscle may provide approximately 70% Cu, 60% Zn and 100% Fe of the recommended dietary reference intake.

Transfer of Heavy Metals Through Three Components: Sediments, Plants and Fish in the Area with Previous Mining Activity

This study aims to evaluate the ecological risk and distribution of heavy metals in sediment, plants and fish in a seriously polluted water reservoir in Krompachy, Slovakia. Special attention was given to the different food web positions of individual fish species (predators, omnivores) and their size. The degree of heavy metal contamination in sediments decreased in the order Cu > Pb > Cr > Hg > Cd, and their mutual proportion was largely consistent with concentrations found in aquatic plants, i.e. water sedges (Carex acutiformis). Of the seven fish species investigated, piscivorous perch (Perca fluviatilis) accumulated higher quantities of metal than fish situated at lower trophic levels. Interestingly, co-equal levels of heavy metals to those found in perch (P. fluviatilis) also occurred in rudd (Scardinius erythrophthalmus). The Hg values in some fish muscles exceeded the maximum permissible limits suggesting a persistent problem of old environmental burden from former mining activities.

Toxicity and bioaccumulation of manganese and chromium in different organs of common carp (Cyprinus carpio) fish

•

Heavy metals effects fishes when its concentration arises from its normal.

•

Bioaccumulation of manganese and chromium was studied in Cyprinus carpio on hematological and biochemical parameters.

•

In organ, bioaccumulation is highest in the gills followed by intestine > muscles > skin > bones.

•

It is concluded that heavy metal can readily bio accumulate in the organs of fish.

The present research work was carried out to determine the bioaccumulation of manganese and chromium in the gills, intestine, muscles, skin and bones, as well as its acute toxicity and effects on hematological and biochemical parameters in Common carp (Cyprinus carpio). Adult carps were exposed for 96 h to manganese sulphate and chromium chloride solution, a sub lethal concentration was used in the experiment. Bioaccumulation was highest in the gills followed by intestine > muscles > skin > bones. The concentration of hematocrit (HCT) (37.3 ± 0.36), hemoglobin (HGB) (9.0 ± 0.04), Red Blood Cells (RBCs) (3.7 ± 0.025), mean corpuscular volume (MCV) (121.2 ± 0.36), mean corpuscular hemoglobin (MCH) (41.3 ± 0.3) and mean corpuscular hemoglobin concentration (MCHC) (41.06 ± 0.072) was significantly higher at 96 h (P < 0.01) after exposure to manganese and chromium, while the concentration of platelets (PLT) (16.8 ± 0.12) and white blood cells (WBCs) (62.7 ± 0.11) was lower at 96 h of exposure. Serum glutamic pyruvic transaminase (SGPT) (40.6 ± 0.4), Blood Urea (13 ± 0.1), serum triglycerides (231.21 ± 0.04), high-density lipoprotein (HDL) (39 ± 0.07), serum Alkaline PO₄ (242 ± 0.2), lactate dehydrogenase (LDH) (1239 ± 13.21), and serum Uric Acid (4.81 ± 0.33) were significantly higher (P < 0.01) at 96 h of exposure. The highest concentration of serum cholesterol (339 ± 0.09), serum reatinine (0.9 ± 0.01), low density lipid (240 ± 0.2) was observed at 24 h. Serum glutamic-oxaloacetic transaminase (SGOT) (19 ± 0.13), and serum albumin were at the highest level at 72 h (3.19 ± 0.07) (P < 0.01) post exposure.

Wastewater remediation of heavy metals and pesticides using rice straw and/or zeolite as bioadsorbents and assessment of treated wastewater reuse in the culture of Nile tilapia (Oreochromis niloticus)

The remediation of wastewater (WW) is a promising solution for limited water sources. This study aimed to evaluate rice straw (RS) and zeolite (Z) as bioadsorbents for the removal of pollutants, including heavy metals (HMs) (cadmium [Cd], nickel [Ni], and lead [Pb]) and malathion (PC), from WW and to assess the suitability of reusing remediated WW in fish rearing units. A total of 11 treatment groups with 3 replicates each were designed with different combinations of RS and/or Z for the treatment of real WW contaminated with HMs and malathion, where the WW remained in contact with the adsorbents for 24 h. Different remediated WWs were used for rearing Nile tilapia (Oreochromis niloticus), which were randomly allocated into 33 glass aquaria representing 11 treatments with 3 replicates each for 30 days. The best remediation efficiency was achieved using a mixture of whole RS (WRS), chopped RS (CRS), and Z (HM-PC-WRS-CRS-Z group), with removal percentages of 92%, 95%, 96%, and 99% for Cd, Ni, Pb, and malathion, respectively. The health status of the aquatic ecosystems was assessed through blood tests to characterize biochemical parameters and through pathological changes of cultured O. niloticus reared in treated WW. A significant (P ˂ 0.05) effect on the blood biochemistry of fish reared in treated WW was found and better biochemical and histologic architecture was observed than that of fish reared in untreated WW. A novel mixture of WRS, CRS, and Z could possibly be a promising low-cost adsorbent for wastewater treatment. Graphical abstract.

Mitigation potential of selenium nanoparticles and riboflavin against arsenic and elevated temperature stress in Pangasianodon hypophthalmus

Climate change impact has disturbed the rainfall pattern worsening the problems of water availability in the aquatic ecosystem of India and other parts of the world. Arsenic pollution, mainly through excessive use of groundwater and other anthropogenic activities, is aggravating in many parts of the world, particularly in South Asia. We evaluated the efficacy of selenium nanoparticles (Se-NPs) and riboflavin (RF) to ameliorate the adverse impacts of elevated temperature and arsenic pollution on growth, anti-oxidative status and immuno-modulation in Pangasianodon hypophthalmus. Se-NPs were synthesized using fish gill employing green synthesis method. Four diets i.e., Se-NPs (0 mg kg^-1) + RF (0 mg kg^-1); Se-NPs (0.5 mg kg^-1) + RF (5 mg kg^-1); Se-NPs (0.5 mg kg^-1) + RF (10 mg kg^-1); and Se-NPs (0.5 mg kg^-1) + RF (15 mg kg^-1) were given in triplicate in a completely randomized block design. The fish were treated in arsenic (1/10th of LC₅₀, 2.68 mg L^-1) and high temperature (34 °C). Supplementation of the Se-NPs and RF in the diets significantly (p < 0.01) enhanced growth performance (weight gain, feed efficiency ratio, protein efficiency ratio, and specific growth rate), anti-oxidative status and immunity of the fish. Nitroblue tetrazolium (NBT), total immunoglobulin, myeloperoxidase and globulin enhanced (p < 0.01) with supplementation (Se-NPs + RF) whereas, albumin and albumin globulin (A:G) ratio (p < 0.01) reduced. Stress biomarkers such as lipid peroxidation in the liver, gill and kidney, blood glucose, heat shock protein 70 in gill and liver as well as serum cortisol reduced (p < 0.01) with supplementation of Se-NPs and RF, whereas, acetylcholine esterase and vitamin C level in both brain and muscle significantly enhanced (p < 0.01) in compared to control and stressors group (As + T) fed with control diet. The fish were treated with pathogenic bacteria after 90 days of experimental trial to observe cumulative mortality and relative survival for a week. The arsenic concentration in experimental water and bioaccumulation in fish tissues was also determined, which indicated that supplementation of Se-NPs and RF significantly reduced (p < 0.01) bioaccumulation. The study concluded that a combination of Se-NPs and RF has the potential to mitigate the stresses of high temperature and As pollution in P. hypophthalmus.

Biomonitoring of Heavy Metals in River Ganga Water, Sediments, Plant, and Fishes of Different Trophic Levels

In this study, the pattern of metals concentration in water, sediment, plants, and three edible fish species (Channa striata, Labeo rohita, and Catla catla) of different trophic levels, captured from Jajmau (Kanpur), an important fishery area of river Ganga in Uttar Pradesh, India was examined. The heavy metals, Ni, Pb, Fe, Cu, Zn, Cd, Cr, and Co, were estimated in the liver, kidney, muscles, and gill tissues of abovesaid species of fish. The highest metal concentration was reported in the bottom feeder fish as compared with the column and surface feeders. The result obtained after analysis of water sample reflects the order of occurrence of heavy metals as Fe > Cr > Pb > Ni > Cd > Zn > Cu > Co. Sediments analysis indicates high concentration of Fe and Cr, making the entire environment from top to bottom, stressful. Target hazard quotient (THQ) and hazard index (HI) of the three species suggest a potential risk to the health of consumers, the humans. Thus, it is inevitable that the river Ganga should be closely monitored to safeguard human health. Graphical Abstract.

Trophic transfer, biomagnification and risk assessments of four common heavy metals in the food web of Laizhou Bay, the Bohai Sea

This study investigated the trophic transfer of four common toxic metals (Cd, Cr, Cu and Hg) in the food web and assessed their potential ecological risks in Laizhou Bay, a spawning area for fishery populations in the Bohai Sea, North China. Based on the predation relations of 43 species that were representatives of the main trophic levels (TLs), a simplified food web was constructed using stomach content analysis and stable nitrogen isotope ratio (δ¹⁵N) analysis. Using copepods as the baseline species (TL = 2.00), the TLs of the organisms ranged from 1.96 (Polychaeta) to 4.47 (Japanese flounder) and showed the following ranking order: predatory pelagic or demersal fish > medium demersal fish > crustacean, cephalopod, small pelagic or demersal fish > zooplankton and Polychaeta. The metals showed different trophic transfer behaviors in the food web. Hg and Cr tended to be efficiently biomagnified between TLs, along the main food chains and in the food web. Cu biodiluted significantly with increasing TLs, while Cd showed no biomagnification or biodilution trends in the food web. At low or moderate levels of Cd and Hg, potential ecological risks were detected in the water and sediments at only a few sites, indicating their overall low ecological risks in the environment. The metals in the important fishery species (four top predatory fish, two cephalopods and eight crustaceans) were below the permissible limits, except for Cd in octopus and paddle crab, which reached or exceeded the most restrictive criteria. Based on the provisional tolerable weekly intake (PTWI) criteria, the safe weekly human consumption levels by humans of the predatory fish, cephalopods and crustaceans were species-specific (0.20-4.44 kg) and should be cautiously assessed.

Assessment of exposure to metals, As and Se in water and sediment of a freshwater reservoir and their bioaccumulation in fish species of different feeding and habitat preferences

The concentrations of metals (Ag, Al, Ba, B, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Hg, Li, Mn, Mo, Ni, Pb, Rb, Sr, Tl, U, V, Zn), As and Se were analyzed in water and sediments from three sites of Río Tercero Reservoir (Córdoba, Argentina) during the wet and the dry season. The dynamics of metals in six fish species (Hoplias malabaricus, Oligosarcus jenynsii, Rhamdia quelen, Bryconamericus iheringii, Astyanax fasciatus and Odontesthes bonariensis) from the reservoir were investigated to discover the possible differential influence of habitat and diet on metal accumulation in the fish. In the abiotic matrix, the highest heavy metal concentrations were observed in sediment. The concentrations of Al, Cu and Pb in water exceeded the limits considered as hazardous for aquatic life. Potential ecological risk analysis of metal concentrations in sediment indicated a low ecological risk in Río Tercero Reservoir in all sampling periods. The enrichment factor indicated that Cu, Pb, Zn and Hg come from anthropogenic sources. Among five different organs, the highest metal levels were found in gills and intestine. Rhamdia quelen and Oligosarcus jenynsii were the species with the highest values of metal accumulation in the whole body. Our study showed that the accumulation pattern of these multi-elements in the different fish species did not respond to diet or habitat, but seemed to be related to the detoxification mechanisms and the metabolism of each organism.

Metabolism and removal of anthracene and lead by a B. subtilis-produced biosurfactant

Most of effluents discharged to the environment contain toxic contaminants such as aromatic compounds and heavy metals which are considered hazardous to the nature and living organisms. In this study, Bacillus subtilis resistant to anthracene and lead was isolated from Persian Gulf sediments. Biosurfactant production was demonstrated using three methods, drop collapse, blood agar and oil spreading. Evaluation of optical density by spectrophotometer showed the bacterial growth in presence of 30 mg/l of anthracene and 50 mg/l of lead. Considerable proportion of anthracene (69.95%) was reduced after 120 h and the maximum percentage of lead absorption (82%) was observed after 150 min. The results indicated that the isolated bacterium was capable of removing anthracene and lead.

Distribution of heavy metals, stable isotope ratios (δ13C and δ15N) and risk assessment of fish from the Yellow River Estuary, China

This study measured the concentrations of eight heavy metals, including copper (Cu), zinc (Zn), lead (Pb), chromium (Cr), cadmium (Cd), iron (Fe), manganese (Mn) and nickel (Ni), and the stable isotope ratios of δ¹³C and δ¹⁵N in 129 fish samples collected from the Yellow River Estuary (YRE) of China. Accumulation characteristics and possible sources of these heavy metals (HMs) were analyzed. The levels of HMs presented high variations among sampling sites, higher concentrations of ∑HMs were observed at the sites closest to the estuary. Cu and Cd in fishes of the YRE were much higher than those found in the fishes of other rivers of China. Furthermore, the mean concentrations of Cu, Zn, Pb, Cr and Cd were also significantly higher than those measured in the fishes of the same region twenty years ago. According to the results of correlation analysis and principal components analysis (PCA), Pb, Cr, Fe, Mn and Ni might be originated from similar sources. The values of δ¹³C and δ¹⁵N presented high variation in fishes, indicating a wide range of energy sources and trophic status of the investigated fish species. The mean concentrations of Pb, Cr and Cd in fishes were all lower than the recommended values enacted by the Chinese government. The human health risk assessment showed that the estimated daily intake (EDI) of these HMs did not exceed the permissible tolerable daily intake (PTDI) and oral reference dose (RfD), indicating a situation of no potential health risk for consumption of these fish species.

Patterns of toxic metals bioaccumulation in a cross-border freshwater reservoir

In freshwater ecosystems toxic metals can follow different routes of bioaccumulation in the organisms' body mass, routes that are similar to electronic circuits, but far more complex due to their hierarchy levels. Reservoirs located on river courses have positive impacts on economic and social development because they concentrate large water volumes used for electrical energy production, water supply, irrigation, industry, aquaculture, providing ecosystems for migratory birds and aquatic species. The aim of the study was to assess the contamination with copper (Cu), cadmium (Cd), lead (Pb), chromium (Cr) and nickel (Ni) of a cross-border reservoir located on River Prut (border between Romania and Republic of Moldova) in a temperate climate zone. Several aspects were considered: seasonal variation of water parameters and toxic metals, bioconcentration in eight fish species and transfer from prey to predator through the food chain, bioaccumulation by two freshwater molluscs separated in size groups and their role as bioindicators of toxic metals pollution. Metals concentrations were measured with an atomic absorption spectrometer (HR-CS GF-AAS). Cadmium, lead, nickel and chromium concentrations limits in water samples were below the detection limits (0.005 μg L^-1Cd, 0.013 μg L^-1Pb and 0.011 μg L^-1Cr) during the monitoring period, suggesting that anthropogenic contamination was insignificant in the studied ecosystem. Fish liver and kidney had specific selectivity for copper (0.9-55.56 μg g^-1) and cadmium (0.097-1.031 μg g^-1) in case of pike-perch and bighead carp. The separation of molluscs in size groups did not prove that toxic metals increase in concentration with the organism age.

Comparative Study of Metal Accumulation in Three Fish Species (Silurus asotus, Cyprinus carpio, and Carassius auratus auratus) from the Jinsha and Tuo Rivers Located Upstream of the Yangtze River, China

The concentrations of lead, chromium, cadmium, arsenic, and mercury were analyzed in the muscle and liver (hepatopancreas) of three fish species (Silurus asotus, Cyprinus carpio, and Carassius auratus auratus) from the Jinsha and Tuo Rivers. The above mentioned metal concentrations in the muscles of the three fish species were below the permissible limits, indicating that these fishes are safe for human consumption. The concentration of mercury in the carnivorous fishes was higher than that in the omnivorous fishes. There was no significant difference in growth rate and the concentration of lead, chromium, cadmium, arsenic, and mercury among the fishes from Panzhihua and Fushun. In the two age groups, the concentration of mercury did not vary significantly with growth rate of fish. The relationship between heavy metal concentration and growth rate of fish varied with metal species, fish species, and fish tissue.

Spatial and length-dependent variation of the risks and benefits of consuming Walleye (Sander vitreus)

Restricted fish consumption due to elevated contaminant levels may limit the intake of essential omega-3 fatty acids, such as eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic (DHA; 22:6n-3) acids. We analyzed lake- and length-specific mercury and EPA+DHA contents in Walleye (Sander vitreus; Mitchell 1818) from 20 waterbodies in Ontario, Canada, and used this information to calculate the theoretical intake of EPA+DHA when the consumption advisories are followed. The stringent consumption advisory resulted in decreased EPA+DHA intake regardless of the EPA+DHA content in Walleye. Walleye length had a strong impact on the EPA+DHA intake mainly because it was positively correlated with the mercury content and thereby consumption advisories. The highest EPA+DHA intake was achieved when smaller Walleye (30-40cm) were consumed. The strong relationship between the consumption advisory and EPA+DHA intake enabled us to develop a more generic regression equation to estimate EPA+DHA intake from the consumption advisories, which we then applied to an additional 1322 waterbodies across Ontario, and 28 lakes from northern USA for which Walleye contaminant data are available but fatty acid data are missing. We estimate that adequate EPA+DHA intake (>250mgday^-1) is achieved in 23% of the studied Ontario lakes, for the general population, when small (30-40cm) Walleye are eaten. Consumption of medium- (41-55cm), and large-sized (60-70cm) Walleye would provide adequate EPA+DHA intake from only 3% and 1% of the lakes, respectively. Our study highlights that mercury contamination, which triggers consumption advisories, strongly limits the suitability of Walleye as the sole dietary source of EPA+DHA to humans.

Chemometric approach to evaluate element distribution in muscle, liver and fish bone of roach (Rutilus rutilus), silver bream (Blicca bjoerkna) and crucian carp (Carassius carassius) from Swarzędzkie Lake (Poland) using ICP-MS and FIAS-CVAAS techniques

The content of elements in fish tissues and organs from Swarzędzkie Lake was investigated in order to evaluate the possible risk associated with their consumption by animals as well as humans. Samples of muscle, liver and fish bone of three fish species; roach (Rutilus rutilus), silver bream (Blicca bjoerkna) and crucian carp (Carassius carassius) were collected from seine catches undertaken as part of the biomanipulation of Swarzędzkie Lake. Element concentration (Al, As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Zn) was determined by inductively coupled plasma mass spectrometry (ICP-MS), with the exception of Hg where the flow injection analysis system cold vapour atomic absorption spectrometry (FIAS-CVAAS) was applied. The study indicated a large variation in the occurrence of the investigated elements in different parts of the fish body. The highest content of Al and Zn was stated in all fish organs for each fish species. The majority of the applied statistical and chemometric methods (e.g., PCA, CA) refer to roach since we had a large number of data for this species. The obtained results were assessed in terms of their accuracy and precision using certified reference material of Fish Muscle ERM BB422.

Age-specific metal and accumulation patterns in different tissues of nase (Chodrostoma nasus) from the Medjuvršje Reservoir

Nase (Chodrostoma nasus L. 1758) specimens of four age classes (1(+) to 4(+)) were caught in July 2013 in the Medjuvršje Reservoir. Concentrations of 14 metals and elements (Al, B, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Si, Sr, Zn) in the muscle, gills and liver were analyzed by inductively-coupled plasma optical spectrometry (ICP-OES). The highest concentrations of Al, Ba, Co, Cr, Mn, Si, Sr and Zn were detected in gills, while Cd, Cu, Fe and Mo reached the highest values in the liver. The majority of the analyzed elements were found in minimal concentrations in the muscle. Younger age classes (1(+), 2(+)) were differentiated by higher concentrations of Mn, Sr and Zn in muscle tissue, while the older ones were mainly differentiated by higher concentrations for Ni and Cu. The youngest age class (1(+)) was distinguished by higher concentrations of Zn, while the oldest age class (4(+)) was distinguished by higher concentrations of Ba, Cu, Mo and Sr in gills. Results obtained were likely caused by differences in the physiology and feeding habits between younger (1-2(+)) and older (3-4(+)) age groups of nase.

Genotoxicity assessment of the Danube River using tissues of freshwater bream (Abramis brama)

This study examines the use of freshwater bream (Abramis brama) as a sentinel organism for genotoxicity assessment of the Danube River using the comet assay. Sampling of bream was performed during February, April, August, and November in 2014 to assess seasonal variation of DNA damage level as a response to genotoxicity in annual cycle. Additionally, concentrations of fecal coliforms and enterococci were analyzed and they indicated a critical to strong level of fecal pollution on investigated locality during annual cycle. Comet assay was performed on blood, liver, and gill cells of bream. DNA damage level was expressed using tail intensity (TI %), Olive tail moment (OTM), and tail length (TL pix). According to TI and OTM, all three tissues had the highest level of DNA damage in August. The lowest level of DNA damage in liver was measured during February, in blood during November, and in gills during April. According to TL, gills had the highest level of DNA damage in February, and liver cells had the lowest level of damage during April. Multiple correspondence analysis (MCA) showed that DNA damage in blood cells is under the strong influence of variations in NO₂, NO₃^-, NH₄⁺ levels and also the variation in temperature and oxygen levels. DNA damage in liver cells is highly associated with the variations of Mn, Fe, Cu, Zn, and PO₄^3- levels. DNA damage in gill cells is strongly affected by the variations of As, Cd, Pb, Cr, and COD (Mn) levels. Freshwater bream is shown to be a potentially good indicator organism in genotoxic potential field studies.

Histopathological changes in gill and liver of Capoeta capoeta living in the Karasu River, Erzurum

The contamination of surface waters by different pollutants is an important problem worldwide. In this study, the histopathological effects of water pollution were investigated on freshwater fish species Capoeta capoeta caught from the Karasu River. Fish were caught at three different sites in the Karasu River, namely, Aşkale, Dumlu, and Serçeme. The histological changes in gill and liver of fish were detected microscopically and evaluated with quantitative analyses. In addition, heavy metals have also been determined in surface water samples from these sites. Results showed that the Aşkale site was polluted by different kinds of heavy metals. In Aşkale site, some heavy metals such as Cd, Al, As, Pb, and Mn levels were mostly detected at concentrations above than the accepted values by the Turkish Standards Institute. The presence of gill and liver histological alterations were assessed by the degree of tissue change (DTC). In gill filaments, hypertrophy and hyperplasia of the gill epithelium, lamellar epithelial lifting, lamellae shortening, vasodilatation, lamellar disorganization, blood congestion, fusion, and aneurysm were observed. In the liver, the changes included an increase in the number and size of melanomacrophage aggregates, nonhomogenous parenchyma, proliferation of the hepatopancreas, sinusoidal dilatation, vacuolization, hypertrophy of the hepatocytes, congestion and degeneration of central vein, blood congestion, pyknotic nucleus, focal necrosis, and hepatic granuloma. The histological lesions were comparatively most severe in liver. The DTC means were varied from slight to moderate of gill and moderate to severe of liver tissue in the Aşkale site, thus the site is considered to be of low quality. Some pathological alterations were observed in the Serçeme site, although their distribution was lower than sites Dumlu and especially Aşkale. The least DTC means of the Serçeme site demonstrated their good environmental quality. The results suggest that there is a close relationship between amounts of pathological alterations and environmental contamination.

Risk Assessment of Heavy Metals in Imported Frozen Fish Scomber scombrus Species Sold in Nigeria: A Case Study in Zaria Metropolis

This study assesses the likely health risks to human contamination of heavy metals from fish consumption. The analysis of the idea of fish destination and status (fishing area) for heavy metals was determined by the assessment of its risk limits (daily intake of metal and health risk index). Variations in the accumulation of heavy metals concentrations were between various tissues/organs (skin, muscle, gills, liver, intestine, kidneys, brain, and bones) across the batches of two fishing origins. Post hoc (Duncan) multicomparison shows that there are significant differences (P<0.05) across batches. The concentrations of heavy metals analyzed, in the investigated tissues of Scomber scombrus, showed higher levels of heavy metals accumulations in the order: Fe>Hg>Pb>Cd>Ni and were above the recommended safety limits outlined by FAO/WHO. However, the consumer’s health risk with the consumption of fish muscles tissues shows that there are greater tendencies for cadmium, lead, and mercury exposure. Also consumption of Scomber scombrus species above the recommended daily intake (stated in this study) might lead to ingestion of heavy metals at unacceptable concentrations.

Heavy metal accumulation and histomorphological alterations in Aphanius fasciatus (Pisces, Cyprinodontidae) from the Gulf of Gabes (Tunisia)

The present study illustrates an analysis of histological changes; cadmium (Cd), copper (Cu) and zinc (Zn) accumulation; and metallothionein (MT) levels in normal and deformed Mediterranean killifish, Aphanius fasciatus (Pisces, Cyprinodontidae), collected from unpolluted (S1) and polluted areas (S2) in the Gulf of Gabes in Tunisia. Metal determination in water and sediment showed that the concentrations were significantly higher (p < 0.0001) in S2 compared to S1. Deformed fish showed a significantly higher accumulation of Cd, Cu, and Zn and high levels of MTs in their tissues compared to normal ones. Histopathological investigations revealed greater changes in gills, kidney, liver, and bone tissues of fish from the polluted area than those recorded in fish from the reference area. In comparison to normal fish of the polluted area (S2), tissue alterations were more developed in deformed specimens of this site. A possible relationship between metallic pollution, incidence of spinal deformities, and histological changes in A. fasciatus in the polluted site was discussed.

Genotoxic effects of water pollution on two fish species living in Karasu River, Erzurum, Turkey

Karasu River, which is the only river in the Erzurum plain, is the source of the Euphrates River (Eastern Anatolia of Turkey). The river is in a serious environmental situation as a result of pollution by agricultural and industrial sewage and domestic discharges. The present study aims to evaluate genotoxic effects of toxic metals in chub, Leuciscus cephalus, and transcaucasian barb, Capoeta capoeta, collected from contaminated site of the Karasu River, in comparison with fish from an unpolluted reference site. Heavy metal concentrations in surface water of the river were determined. The condition factor (CF) was taken as a general biomarker of the health of the fish, and genotoxicity assays such as micronucleus (MN) and other nuclear abnormalities (NA) were carried out on the fish species studied. MN and NA such as kidney-shaped nucleus, notched nucleus, binucleated, lobed nucleus, and blebbed nucleus were assessed in peripheral blood erythrocytes, gill epithelial cells, and liver cells of the fish. A significant decrease in CF values associated with a significant elevation in MN and NA frequencies was observed in fish collected from the polluted sites compared with those from the reference site. Results of the current study show the significance of integrating a set of biomarkers to identify the effects of anthropogenic pollution. High concentrations of heavy metals have a potential genotoxic effects, and the toxicity is possibly related to industrial, agricultural, and domestic activities.

Metal concentration in water, sediment and four fish species from Lake Titicaca reveals a large-scale environmental concern

Although intensive mining activity and urban sewage discharge are major sources of metal inputs to Lake Titicaca, the risk posed by metal pollution to wildlife and human populations has been poorly studied. In this study we compared the concentrations of Cu, Zn, Cd, Hg, Pb, Co, and Fe in water, sediment, and two tissues (liver and muscle) of four fish species (Odontesthes bonariensis, Orestias luteus, Orestias agassii, and Trichomycterus rivulatus) across important fishery areas in Lake Titicaca. The concentration of Pb in water at the discharge sites of the main rivers and of most elements, with the exception of Co and Fe, in all fish collected in this study exceeded the safety thresholds established by international legislation. The highest metal concentrations were observed in benthopelagic species, and liver tissue was identified as the main depository for all metals with the exception of mercury. The metal bioaccumulation pattern in fish was weakly related to the metal concentrations in the environment with the exception of Hg at the most polluted location, partly explained by the different metabolic role of essential and non-essential elements and the influence of other factors such as species' ecology and individual traits in the bioaccumulation of most metals. As metal pollution extended across the study area and high metal concentrations were detected in all four fish species, we urge the authorities to enforce legislation for water and fish consumption and to evaluate the effects of metal pollution on fish health.

The trace element analysis in freshwater fish species, water and sediment in Iyidere stream (Rize-Turkey)

Many environmental problems like dam construction, agricultural debris, flooding and industrial establishments threaten Iyidere stream (Rize, Turkey) on the southeastern coast of the Black Sea (Turkey). The trace element concentrations in water, fish and sediments in lyidere stream (Rize, Turkey) were investigated in this study. The concentration of six different elements in ten freshwater fish species and sediment was determined using energy dispersive X-ray fluorescence method. A radioisotope excited X-ray fluorescence analysis using the method of multiple standard addition is applied for the elemental analysis of fish and sediments. Water samples for trace metals were analyzed using standard spectrophotometry methods. A qualitative analysis of spectral peaks showed that ten different freshwater fish samples (Chondrostoma colchicum, Chalcalburnus chalcoides, Salmo trutta labrax, Alburnoides bipunctatus, Leuciscus cephalus, Barbus taurus escherichia, Capoeta tinca, Neogobius kessleri, Rutilus frisii, Lampetra lanceolata) and sediment contained phosphorus (P), sulphur (S), chlorine (Cl), potassium (K), calcium (Ca) and titanium (Ti). Heavy metals as toxic elements for biota (Pb, Cd, Hg, Zn and Mn etc.) were not detected in fish, water and sediments. Thus, It can be declared that freshwater fish of Iyidere does not contains health risks for consumers in terms of metal pollution.

Distribution of metals (Fe, Mn, Zn, Cu) in fish tissues in two lakes of different trophy in Northwestern Poland

This study presents concentrations of iron, manganese, zinc, and copper in selected tissues of two fish species: pike (Esox lucius L.) and bream (Abramis brama L.) living in lakes Ińsko and Wisola, Northwestern Poland. The lakes differ in their trophic status. The effect of gender and environmental conditions on metals accumulation was also investigated. Metal analyses were performed using inductively coupled plasma atomic emission spectroscopy. Considering all studied fish species and tissues, the average metal concentrations (micrograms per gram wet weight) in both lakes occurred in the following ranges: Fe 0.8-240.6, Mn 0.2-8.4, Zn 3.0-185.9, and Cu 0.14-7.76. The lowest levels of the studied metals were always detected in the muscles. The spleen, kidneys, and liver were found to accumulate the highest amounts of Fe. In the case of the other metals, the highest levels were found, as follows: Mn in skin, gills, and gonads, Zn in digestive tract and gills, Cu in liver. Heavy metal content in fish gonads was observed to be sex dependent.

Distribution and relationships of As, Cd, Pb and Hg in freshwater fish from five French fishing areas

The concentrations of arsenic, cadmium, mercury and lead in 149 muscle samples of eight freshwater fish species (European eel, bream, common carp, European catfish, roach, perch, pike and pikeperch) from five different French fishing areas from contaminated and control sites were measured by inductively coupled plasma mass spectrometry after microwave digestion under pressure. No significant correlation was found between the condition factor (CF), based on the length-mass relationship, and As, Cd and Pb levels in all the samples analysed, but a positive correlation was detected between CF and Hg levels (P<0.0001, R=0.49). Positive correlations with body length were only found for Hg in roach (P<0.05, R=0.32) and Pb in bream (P<0.05, R=0.48) and correlations with both body weight and length were also found for Hg in pike (P<0.05, R=0.90 and 0.86) and Cd in European eel (P<0.01, R=-0.35 and -0.37). The average content and the standard deviation in fish muscle samples was 0.007±0.012, 0.102±0.077, 0.142±0.097 and 0.035±0.053 mg kg(-1) of wet mass for Cd, As, Hg and Pb, respectively. Significant differences were established between groups of predatory fish and non-predatory fish for Hg and Pb, and between control and contaminated sites in the whole selection and also within feeding guilds, i.e. the values of Hg in the benthophagic fish were significantly different between these sites. Finally, these results were also compared for each species with previous French and European studies.

Heavy metals distribution in muscle, liver, kidney and gill of European catfish (Silurus glanis) from Italian Rivers

The accumulation of heavy metals in freshwaters has direct consequences to man and ecosystem. Thus, in this study, the concentrations of mercury, cadmium, lead, arsenic and chromium in organs of the predator European catfish (Silurus glanis) were investigated. Samples were collected annually in five sites covering the area of the Po River (North Italy) between 2007 and 2009. Metals were differently distributed in the various organs, the highest concentrations of Hg were found in muscle and liver, Cd in kidney, Pb in gill and liver, as in muscle, and of Cr in gill and liver. Our survey found Hg exceeding the Maximum Levels (MLs) of 0.5 ppm in 18% of samples, while Pb and Cd were lower than the MLs set by European regulations in muscle tissues (1881/2006/EC and 629/2008/EC). Hg concentrations were significantly related to sampling stations studied, according to the presence of many industrial activities in the catchment area of Bormida and Tanaro Rivers. The finding that Hg did not fit food fish legislation limits indicated that S. glanis flesh might not be utilised for human consumption. A close monitoring of metals pollution is strongly recommended especially in piscivorous fish, cause their bioaccumulation capacity.

Spectroscopic analyses of pollutants in water, sediment and fish

Water ways in Egypt is suffering from continual discharge without adequate treatment especially in the Delta and greater Cairo area. Accordingly water, sediments and catfishes were collected from El Mouheet El Youmna drain in Giza. Cd, Cr, Pb and Zn were determined furthermore the molecular structure of sediment and catfish were conducted with FTIR spectroscopy. Although studied metals were lower in water, higher values are recorded in sediment and catfish samples. FTIR shows possible interaction among metals and organic structures mainly proteins. The bioaccumulation of Pb and Cd proportion was significantly increased in the liver tissues of catfish. A correlation coefficient among sediment and fish liver metals accumulation exist. This infers that the waste assimilation capacity for the drain is high, a phenomena that could be ascribed to dilution, sedimentation and continual water exchange. Furthermore, the genotoxicity affect in catfish genomic corroborates the genus diagnostic markers which attributed to long pollution. This is an indication that agriculture and industrial wastes discharged into the drain has badly a significant effect on the ecological balance.

Metals concentrations in Nile tilapia Oreochromis niloticus () from illegal fish farm in Al-Minufiya Province, Egypt, and their effects on some tissues structures

This study clarified the suitability of fishes caught from illegal fish farms to human consumption and their hazards to public health. For this purpose, the concentrations of some metals (Al, Cd, Pb, Hg and Ni) in water and Nile tilapia (Oreochromis niloticus) fish samples collected from an illegal fish farm, in addition to pathological conditions of the fish tissues, were examined. The illegal farm water was found to be heavily polluted with metals which far exceeded the permissible limits. It was found that metals accumulated in tissues of O. niloticus in concentrations higher than those of farm water. Kidney of O. niloticus contained the highest concentrations of the detected metals, while muscle and skin contained the lowest concentrations. The examination of fish tissues revealed various histopathological lesions which related directly to the pollution of the illegal farm water. Moreover, metals levels in O. niloticus muscle were higher than the maximum permissible levels for human consumption. Consequently, the flesh of fishes from the illegal farms could be considered hazardous to human health. Therefore, warning against eating fish caught from the illegal fish farms should be announced. Moreover, removal of such illegal fish farms is necessary for the public health protection.

Perch and its parasites as heavy metal biomonitors in a freshwater environment: the case study of the Ružín water reservoir, Slovakia

Heavy metal concentrations were determined in 43 perches (Perca fluviatilis) and in two of its most common parasites, the acanthocephalan Acanthocephalus lucii and the cestode Proteocephalus percae, collected in the period 2009–2010 from Ružín, a seriously polluted water reservoir in Slovakia. Samples of muscle, liver, kidney, brain, male and female reproductive organs and adipose tissue of fish and both parasites were analyzed for As, Cd, Cr, Cu, Hg, Mn, Ni, Pb and Zn, by ICP-MS. Mean concentrations of individual heavy metals in all fish samples decreased in the order zinc > copper > manganese > mercury > arsenic > chromium > cadmium > nickel > lead. Zinc was found to be the dominant element and its antagonistic interaction with copper was confirmed. The kidney was a key target organ receiving the highest mean concentrations of all analyzed metals, but some metals showed specific affinity for particular tissues. In terms of human health, concentration of Hg in fish muscle, which exceeded more than two-times its maximum level admitted in foodstuffs in European countries, is of great importance and should be taken into account. Bioaccumulation factors (C_[parasite]/C_{[fish tissue]}) calculated for all elements indicated much higher detection skills of A. lucii and P. percae parasites than fish organs and hence, present results allow proposing both parasite models as useful tools to monitor aquatic environmental quality. Acanthocephalans, however, seem to be superior for heavy metal monitoring, also demonstrated under experimental conditions. Present results also indicate the decreasing heavy metal burden of the reservoir and its gradual recovery in the course of time.

Fuzzy logic modeling of bioaccumulation pattern of metals in coastal biota of Ondo State, Nigeria

The accumulation patterns of ten metals in tissues of plant, Eichornia crassipes, and fishes, Hydrocynus forskahlii and Oreochromis mossambicus, were modeled with simple fuzzy classification (SFC) to assess toxic effects of anthropogenic activities on the coastal biota. The plant sample was separated into root, stem, and leaves and the fishes into bones, internal tissues, and muscles. They were analyzed for As, Cd, Cr, Cu, Ni, Pb, V, Fe, Mn, and Zn after wet oxidation of their dried samples. The results were converted into membership functions of five accumulation classes and aggregated with SFC. The classification results showed that there was no metal accumulation in the plant parts while the fishes were classified into low accumulation category. The internal tissues of the fishes had higher metal accumulation than the other parts. Generally, Fe and Mn had highest concentrations in the biota but are natural to the area and may not constitute significant risk. Cr had the highest transfer and accumulation from the coastal water into the aquatic lives and may be indicative of risk prone system being a toxic metal. Metal contaminations in the zone had not significantly accumulated in the biota making them less prone to risk associated with metal accumulation.

Acute toxicity bioassay of mercury and silver on Capoeta fusca (black fish)

Since toxicity is based on the effect that a toxicant produces at a target site within an organism, establishing the relationship between the concentration of substance at the target site and the subsequent toxic effect can provide a tool for predicting toxicity. The behavior of a single toxicant could not be fully understood without the knowledge of the fact the physical and biochemical properties of substances that can change. To understand this, the acute toxicity of mercury (as HgSO₄) and silver (as AgSO₄) to Capoeta fusca (6 treatments in triplicate) was determined. During September 2009, C. fusca belonging to the family Cyprinidae, weighing 2.95 (±0.55) g, were obtained from qanats in Birjand, East of Iran. The fish were maintained in an aquarium system at a holding temperature of 21 (±0.2) and were allowed to adjust to lab conditions for 1 week before experimentation. The lethal concentration 50 (LC₅₀) values for HgSO₄ at 24, 48, 72, and 96 h of exposure were 0.32, 0.28, 0.26, and 0.24 mg L⁻¹, respectively. Also, the LC₅₀ values for AgSO₄ at 24, 48, 72, and 96 h of exposure were 0.014, 0.013, 0.013, and 0.013 mg L⁻¹, respectively. Results of this study showed that C. fusca was very sensitive to AgSO₄.

Histopathological changes in gill, liver and kidney of neotropical fish Colossoma macropomum exposed to paraquat at different temperatures

This work focused on the histological alterations in gill, liver and kidney of fish Colossoma macropomum exposed to different temperatures (18°C, 29°C, 35°C) with 10mg/L of herbicide Paraquat (PQ), during 21 days. The fish exhibited histopathological changes in these tissues; the most important alteration in gills was telangiectasis. Liver showed debris accumulation inside cytoplasm hepatocytes, karyolysis, karyohesis and a decrease in the size of sinusoids. Hyperplasia of melanomacrophagic centers (MMC) and an increase in basophils were observed in kidney. The lesion inducing by PQ and the damage in tissue depended of temperature exposure fish. The severity of lesions clearly differed among organs with the liver showing the most extensive damages followed in order by the kidney and gills. In PQ/18°C group it was observed the changes in the pattern of lesions, with kidney showing higher damage followed gills and liver.

Combined use of bioindicators and passive samplers for the assessment of river water contamination with metals

In autumn 2005, the site-specific variability of cytosolic metal and protein concentrations in gills of European chub from the Sava River could be mostly associated with gill mass variability. In spring 2006, the correlations of metals and proteins with gill mass were mainly nonsignificant, and their site-specific variability could be presumably associated with river water pollution. The spring cytosolic concentrations of Zn, Cu, and Mn did not differ significantly between the sites (medians: 8.37-11.34 microg ml(-1), 68.2-86.2 ng ml(-1), and 55.9-68.6 ng ml(-1), respectively). Increased cytosolic Cd concentrations were obtained at Oborovo and Lukavec Posavski (median: 4.01 ng ml(-1))-the sites influenced by pollution sources from two major urban areas-compared with the remaining sampling sites (median: 1.93 ng ml(-1)). Cytosolic Fe concentrations were almost two times higher at Jasenovac (median: 11.98 microg ml(-1)) compared with the concentrations at Sava-Zagreb (median: 6.72 microg ml(-1)). Labile Fe concentrations measured in river water with passive samplers indicated that cytosolic Fe concentrations in the spring possibly reflected water-borne Fe uptake. The spring cytosolic protein concentrations decreased from upstream (Otok Samoborski: 27.2 +/- 5.6 mg ml(-1)) toward the downstream sites (Lukavec Posavski: 14.8 +/- 2.8 mg ml(-1)), possibly because of the influence of organic pollution and water toxicity. The spring period seems to be a more appropriate season for the assessment of the river water pollution if chub gills are used as the target organ.

Determination of heavy metal levels in water, sediment and tissues of tench (Tinca tinca L., 1758) from Beyşehir Lake (Turkey)

In the present study, some heavy metals (Cu, Fe, Zn and Mn) were seasonally determined in water, sediment and some tissues of fish Tinca tinca from Beyşehir Lake, which is an important bird nesting and visiting area, a water source for irrigation and drinking. In the water, Fe has the highest concentrations among the studied metals. Generally, the metal concentrations increased in the hottest period decreased in warm seasons. Results for levels in water were compared with national and international water quality guidelines, as well as literature data reported for the lakes. Fe was the highest in sediment samples, also Cu and Zn were the highest in spring, while Fe and Mn were in autumn. Among the heavy metals studied, Cu and Mn were below the detection limits in some tissues. Generally, higher concentrations of the tested metals were found in the summer and winter, compared with those during the autumn and spring seasons. High levels of heavy metals were found in liver of T. tinca, while low levels in muscle samples. Metal concentrations in the muscle of examined fish were within the safety permissible levels for human consumption. The present study shows that precautions need to be taken in order to prevent further heavy metal pollution.