Use of performance indicators in evaluating chronic metal exposure in wild yellow perch (Perca flavescens)

The objective of this study was to evaluate the effects of copper exposure on swimming performance and gill-binding characteristics of wild yellow perch (Perca flavescens), a species endemic to metal-contaminated lakes of the Sudbury region in northern Ontario. Yellow perch were collected from lakes varying in the degree of metal contamination (Cu = 1-21 microg/l), on two separate occasions for the investigation of swim performance and the analysis of gill-binding characteristics. Swim performance tests indicated that yellow perch from the contaminated lake had slightly greater endurance in a fixed velocity sprint test than fish from reference lakes, although the analysis of critical swimming speeds (U(crit)) did not reveal this same distinction between the groups. Differential sprint performance was in part due to differences in fish size within contaminated and reference lakes. Yellow perch from the contaminated lake also had higher resting levels of muscle glycogen and greater lactate production during high intensity exercise compared to yellow perch from the reference site. Acclimation occurred in the metal-contaminated yellow perch, as seen by the significantly elevated time to death (LT50) during an acutely lethal challenge to 600 microg Cu/l. However, gills from perch from the contaminated lake accumulated about three times more copper at death. In contrast, at a lower exposure range of water-copper (10-400 microg/l), the gills of fish from the contaminated lake tended to saturate with copper at lower concentrations than gills of fish from the reference lake (approximately 8 microg versus 23 microg Cu/g of gill tissue). In addition, perch from the contaminated lake exhibited a lower rate of sodium loss during the acute exposure to copper at approximately 10 to 600 microg Cu/l. This study suggests that the amount of copper bound to (or accumulated within) the gills may not be diagnostic of acute toxicity for wild yellow perch from metal-contaminated lakes.     

Hormonal,morphological, and physiological responses of yellow perch (Perca flavescens) to chronic environmental metal exposures

The effects of a chronic environmental exposure to metals on the hormonal, physiological, and reproductive status were assessed in yellow perch (Perca flavescens) sampled in six lakes situated along a contamination gradient of Cd, Zn, Cu, Pb, and Ni in the mining region of Rouyn-Noranda, Québec. Fish were captured in the summer and fall, and sampled before or after a confinement of one hour. Metal concentrations in the kidneys and the interrenal tissues (homologous to mammalian adrenals) were measured to compare tissue-specific metal accumulation. An exposure-related decrease of condition factor, gonadosomatic index (GSI), branchial Na+/K(+)-ATPase activity, plasma thyroxine (T4), triiodothyronine (T3), and 17 beta-estradiol and an impaired capacity to enhance cortisol levels after confinement were observed. Fish from the metal-contaminated lakes possessed gonads at less mature stages and exhibited structural alterations of their gills, interrenal cells, and thyroid follicle epithelium. A comparison of the morphological, biochemical, and physiological endpoints measured in the present study revealed that plasma concentrations of hormones and parameters of gill function were the most affected by metal contamination. The results of this study indicate that lifelong exposures to sublethal concentrations of metals alter the physiological functions of fish and delay reproduction.     

The Importance of Metallothionein for the Accumulation of Copper,Zinc and Cadmium in Environmentally Exposed Perch,Perca fluviatilis*

Abstract: A field study of the role of metallothionein (MT) in the binding of heavy metals in perch (Perca fluviatilis), exposed to moderate levels of copper, zinc and cadmium, was performed. Perch were sampled at four sites in Sweden in September during two consecutive years. Two sites were located in the vicinity of a brassworks and two outside the emission range. The first year, fish from the two brassworks sites and from one of the uncontaminated sites were collected. The second year, fish from the most contaminated site and from the two uncontaminated sites were caught. The levels of hepatic copper, zinc and cadmium reflected the concentrations of these metals in water and were increased in fish from the two contaminated sites. The level of cadmium in liver was relatively low. MT was induced in liver of perch caught at the most contaminated site. The hepatic MT content in individual livers correlated well to the accumulation of copper (r=0.85, P<0.001) and zinc (r=0.75, P<0.001). There was a low but significant correlation between the levels of MT and cadmium in the liver (r=0.48, P<0.001). The relationship between MT and metals was very similar both years. Subcellular fractionation of the metals in the liver revealed that an induction of MT was followed by an increased amount of copper, zinc and cadmium bound to the protein. The relative fraction of the total hepatic copper and cadmium bound to MT was increased at the most contaminated site, whereas there was no difference in subcellular distribution of zinc between the sites. In perch from the most contaminated site, the portions of hepatic copper, zinc and cadmium found in the cytosolic fraction were 70, 57 and 81%, respectively. Seventy-one % of the copper, 29% of the zinc and 84% of the cadmium found in hepatic cytosol of fish from the same site, eluted together with MT after gel filtration chromatography. The analysis of the subcellular distribution of copper, zinc and cadmium demonstrates that MT is responsible for the binding of a large amount of the total hepatic cellular content of copper and cadmium in perch.     

Impairment of metabolic capacities in copper and calcium contaminated wild yellow perch (Perca flavescens)

This study examined variations in resting oxygen consumption rate (ROCR), post-exercise oxygen consumption rate, relative scope for activity (RSA), liver and muscle aerobic and anaerobic capacities (using citrate synthase (CS) and lactate dehydrogenase, respectively, as indicators), and tissue biosynthetic capacities (using nucleoside diphosphate kinase (NDPK) as an indicator), in wild yellow perch from four lakes varying in copper (Cu) and cadmium (Cd) contamination. Liver Cu and Cd concentrations largely reflected environmental contamination and were positively correlated with liver protein concentrations and NDPK activities. Our results suggest that metal contamination leads to an upregulation of liver protein metabolism, presumably at least in part for the purpose of metal detoxification. In contrast, muscle NDPK activities decreased with increasing liver Cd concentrations and NDPK activities. There was a 25% decrease in ROCR for a doubling of liver Cu concentrations and a 42% decrease in RSA for a doubling of liver Cd concentrations in the range studied. Cu contamination was also associated with lower muscle CS activities. Our results support previous findings of impaired aerobic capacities in the muscle of metal-contaminated fish, and demonstrate that this impairment is also reflected in aerobic capacities of whole fish. The evidence presented suggests that mitochondria may be primary targets for inhibition by Cu, and that Cd may reduce gill respiratory capacity. Muscle aerobic and anaerobic capacities were inversely related. This work indicates that metal exposure of wild yellow perch leads to a wide range of disturbances in metabolic capacities.     

The importance of metallothionein for the accumulation of copper, zinc and cadmium in environmentally exposed perch, Perca fluviatilis

A field study of the role of metallothionein (MT) in the binding of heavy metals in perch (Perca fluviatilis), exposed to moderate levels of copper, zinc and cadmium, was performed. Perch were sampled at four sites in Sweden in September during two consecutive years. Two sites were located in the vicinity of a brassworks and two outside the emission range. The first year, fish from the two brassworks sites and from one of the uncontaminated sites were collected. The second year, fish from the most contaminated site and from the two uncontaminated sites were caught. The levels of hepatic copper, zinc and cadmium reflected the concentrations of these metals in water and were increased in fish from the two contaminated sites. The level of cadmium in liver was relatively low. MT was induced in liver of perch caught at the most contaminated site. The hepatic MT content in individual livers correlated well to the accumulation of copper (r = 0.85, P less than 0.001) and zinc (r = 0.75, P less than 0.001). There was a low but significant correlation between the levels of MT and cadmium in the liver (r = 0.48, P less than 0.001). The relationship between MT and metals was very similar both years. Subcellular fractionation of the metals in the liver revealed that an induction of MT was followed by an increased amount of copper, zinc and cadmium bound to the protein. The relative fraction of the total hepatic copper and cadmium bound to MT was increased at the most contaminated site, whereas there was no difference in subcellular distribution of zinc between the sites. In perch from the most contaminated site, the portions of hepatic copper, zinc and cadmium found in the cytosolic fraction were 70, 57 and 81%, respectively. Seventy-one % of the copper, 29% of the zinc and 84% of the cadmium found in hepatic cytosol of fish from the same site, eluted together with MT after gel filtration chromatography. The analysis of the subcellular distribution of copper, zinc and cadmium demonstrates that MT is responsible for the binding of a large amount of the total hepatic cellular content of copper and cadmium in perch.     

Evolutionary ecotoxicology of wild yellow perch (Perca flavescens) populations chronically exposed to a polymetallic gradient

Depending on such factors as the intensity and duration of the exposure, and the genetic diversity and connectedness of the starting population, exposure to elevated metal concentrations can result in population level alterations such as demographic bottlenecks or metal-induced selection. These processes can be revealed using a population genetic approach, and have important implications with respect to population persistence. The main objective of this study was to examine the role of metal contamination in driving evolutionary changes by documenting patterns of genetic diversity within and among populations of wild yellow perch (Perca flavescens) in two major mining regions that have been subjected to metal emissions from smelters for at least 80 years; Rouyn-Noranda, Québec and Sudbury, Ontario. Yellow perch populations from ten lakes representing a gradient of metal contamination in each of the two lake systems were evaluated concurrently to reveal relationships between metal contamination and genetic diversity. These replicated sympatric observations allowed us to evaluate correlations and infer causal relationships between metal exposure and evolutionary responses in this species. Within-population gene diversity over all loci was negatively correlated with liver cadmium contamination (P<0.001; r(2)=0.47). Similarly, a negative correlation between gene diversity and liver copper contamination was observed at a single locus (Pfla L1, P=0.005; r(2)=0.33), suggesting a local effect of copper contamination. Internal relatedness, an index of individual diversity, presented the opposite tendency as the more contaminated individuals were more diverse than were the less contaminated ones in contaminated and reference populations. Our results thus suggest that the selective response to contamination has been large enough to substantially reduce the within-population genetic diversity, despite the fact that the less inbred individuals may be favoured by selection within any given population. Overall, our results reveal that >50 years of metal contamination have significantly impacted patterns of genetic diversity observed among populations of wild yellow perch in mining areas and as such, may have affected the capacity of populations to respond to future environmental changes.     

Cadmium-handling strategies in two chronically exposed indigenous freshwater organisms--the yellow perch (Perca flavescens) and the floater mollusc (Pyganodon grandis)

Laboratory experiments on a variety of aquatic organisms suggest that metallothionein-like proteins (MT) play an important role in the regulation of essential metals, and in the sequestration and detoxification of non-essential metals (e.g., Cd). However, the importance of metallothionein production relative to alternative strategies of metal detoxification, and its effectiveness in metal detoxification, remain largely unexplored in field situations. In the present study we explored metal-handling strategies in an adult benthic bivalve (Pyganodon grandis) and in juvenile yellow perch (Perca flavescens), exposed to Cd in their natural habitat. The two biomonitor species were collected from lakes located along a Cd concentration gradient. Ambient dissolved Cd concentrations were determined by in situ dialysis as a measure of metal exposure. Sub-cellular Cd partitioning was determined in target tissues (bivalve gills and digestive gland; perch liver) by differential centrifugation, and metallothionein was measured independently by a mercury-saturation assay in the bivalve tissues. Malondialdehyde concentrations were measured as a potential indicator of oxidative stress. Ambient dissolved Cd concentrations ranged from 0.06 to 0.57 nM in the nine lakes from which bivalves were collected, and from < 0.3 to 6.7 nM in the eight lakes from which yellow perch were sampled. Bioaccumulated Cd also varied from lake to lake, more so for the bivalve than for the yellow perch; the [Cd]max/[Cd]min ratios for the various tissues decreased in the order: bivalve gill Cd 28 > bivalve digestive gland Cd 18 > perch hepatic Cd 14. In the two lakes that were common to both the bivalve and perch studies, i.e. lakes Opasatica and Vaudray, accumulated Cd concentrations were consistently higher in the bivalve than in the perch. Cadmium-handling strategies were similar in the bivalve digestive gland and perch liver, in that Cd was mainly associated with the heat-stable protein (HSP) fraction. Furthermore, in these organs the contributions from the "mitochondria" and "lysosomes + microsomes" fractions were consistently higher than in the gill tissue. In the bivalve gill, the HSP fraction could only account for a small proportion (10+/-3%) of the total Cd burden, and the metal was instead largely sequestered in calcium concretions (58+/-13%). Along the Cd-exposure gradient, Cd detoxification appeared to be reasonably effective in the bivalve gill and digestive gland, as judged from the protection of the heat-denaturable protein (HDP) fraction. However, in both organs Cd concentrations did increase in potentially metal-sensitive organelles (mitochondria), and malondialdehyde concentrations increased along the exposure gradient in the gills (but not in the digestive gland). Cadmium detoxification seemed less effective in juvenile yellow perch. As total hepatic Cd increased, Cd concentrations increased in all sub-cellular fractions, including the HDP fraction that was well protected in the bivalve. The relative proportions of Cd in the various fractions did not vary appreciably along the exposure gradient and there was no evidence of a threshold exposure concentration below which sensitive metal pools were protected.     

Can mercury in fish be reduced by water level management? Evaluating the effects of water level fluctuation on mercury accumulation in yellow perch (Perca flavescens)

Mercury (Hg) contamination of fisheries is a major concern for resource managers of many temperate lakes. Anthropogenic Hg contamination is largely derived from atmospheric deposition within a lake’s watershed, but its incorporation into the food web is facilitated by bacterial activity in sediments. Temporal variation in Hg content of fish (young-of-year yellow perch) in the regulated lakes of the Rainy–Namakan complex (on the border of the United States and Canada) has been linked to water level (WL) fluctuations, presumably through variation in sediment inundation. As a result, Hg contamination of fish has been linked to international regulations of WL fluctuation. Here we assess the relationship between WL fluctuations and fish Hg content using a 10-year dataset covering six lakes. Within-year WL rise did not appear in strongly supported models of fish Hg, but year-to-year variation in maximum water levels (?maxWL) was positively associated with fish Hg content. This WL effect varied in magnitude among lakes: In Crane Lake, a 1 m increase in ?maxWL from the previous year was associated with a 108 ng increase in fish Hg content (per gram wet weight), while the same WL change in Kabetogama was associated with only a 5 ng increase in fish Hg content. In half the lakes sampled here, effect sizes could not be distinguished from zero. Given the persistent and wide-ranging extent of Hg contamination and the large number of regulated waterways, future research is needed to identify the conditions in which WL fluctuations influence fish Hg content.     

Fasting augments PCB impact on liver metabolism in anadromous arctic char.

Anadromous arctic char (Salvelinus alpinus) undertake short feeding migrations to seawater every summer and accumulate lipids, while the rest of the year is spent in fresh water where the accumulated lipid reserves are mobilized. We tested the hypothesis that winter fasting and the associated polychlorinated biphenyls' (PCBs) redistribution from lipid depots to critical tissues impair the liver metabolic capacity in these animals. Char were administered Aroclor 1254 (0, 1, 10, and 100 mg/kg body mass) orally and maintained for 4 months without feeding to mimic seasonal winter fasting, while fed groups (0 and 100 mg Aroclor 1254/kg) were maintained for comparison. A clear dose-related increase in PCB accumulation and cytochrome P4501A (CYP1A) protein content was observed in the livers of fasted fish. This PCB concentration and CYP1A response with the high dose of Aroclor were 1.5-fold and 3-fold greater in the fasted than in the fed fish, respectively. In fed fish, PCB exposure lowered liver glycogen content, whereas none of the other metabolic indicators were significantly affected. In fasted fish, PCB exposure depressed liver glycogen content and activities of glucose-6-phosphate dehydrogenase, alanine aminotransferase, lactate dehydrogenase, and phosphoenolpyruvate carboxykinase and elevated 3-hydroxyacylcoA dehydrogenase activity and glucocorticoid receptor protein expression. There were no significant impacts of PCB on heat shock protein 70 (hsp70) and hsp90 contents in either fed or fasted fish. Collectively, our study demonstrates that winter emaciation associated with the anadromous lifestyle predisposes arctic char to PCB impact on hepatic metabolism including disruption of the adaptive metabolic responses to extended fasting.     

Sub-cellular partitioning of cadmium, copper, nickel and zinc in indigenous yellow perch (Perca flavescens) sampled along a polymetallic gradient

Sub-cellular metal distributions were studied in indigenous yellow perch (Perca flavescens) collected from eight lakes located along a cadmium (Cd), copper (Cu), nickel (Ni) and zinc (Zn) concentration gradient. Ambient dissolved metal concentrations were measured to evaluate exposure and total hepatic metal concentrations were determined as a measure of metal bioaccumulation. Metal partitioning among potentially metal-sensitive fractions (cytosolic enzymes, organelles) and detoxified metal fractions (metallothionein) was determined after differential centrifugation of fish liver homogenates. Major proportions of hepatic Cd and Cu were found in the heat-stable cytosolic peptides and proteins fraction (HSP), a fraction including metallothioneins, whereas the potentially metal-sensitive heat-denaturable proteins fraction (HDP) was the largest contributor to the total Ni and Zn burdens. The concentrations of Cd, Cu and Ni (but not Zn) in each sub-cellular fraction increased along the metal contamination gradient, but the relative contributions of each fraction to the total burden of each of these metals remained generally constant. For these chronically exposed fish there was no threshold exposure concentration below which binding of Cd or Ni to the heat-denaturable protein fraction did not occur. The presence of Cd and Ni in the HDP fraction, even for low chronic exposure concentrations, suggests that metal detoxification was imperfect, i.e. that P. flavescens was subject to some metal-related stress even under these conditions.     

Branchial cadmium and copper binding and intestinal cadmium uptake in wild yellow perch (Perca flavescens) from clean and metal-contaminated lakes

Branchial binding kinetics and gastro-intestinal uptake of copper and cadmium where examined in yellow perch (Perca flavescens) from a metal-contaminated lake (Hannah Lake, Sudbury, Ontario, Canada) and an uncontaminated lake (James Lake, North Bay, Ontario, Canada). An in vivo approach was taken for gill binding comparisons while an in vitro gut binding assay was employed for gastro-intestinal tract (GIT) uptake analysis. By investigating metal uptake at the gill and the gut we cover the two main routes of metal entry into fish. Comparisons of water and sediment chemistries, metal burdens in benthic invertebrate, and metal burdens in the livers of perch from the two study lakes clearly show that yellow perch from Hannah L. are chronically exposed to a highly metal-contaminated environment compared to a reference lake. We found that metal-contaminated yellow perch showed no significant difference in gill Cd binding compared to reference fish, but they did show significant decreases in new Cd binding and absorption in their GITs. The results show that gill Cd binding may involve low-capacity, high-affinity binding sites, while gastro-intestinal Cd uptake involves binding sites that are high-capacity, low-affinity. From this we infer that Cd may be more critically controlled at the gut rather than gills. Significant differences in branchial Cu binding (increased binding) were observed in metal-contaminated yellow perch. We suggest that chronic waterborne exposure to Cu (and/or other metals) may be the dominant influence in gill Cu binding rather than chronic exposure to high Cu diets. We give supporting evidence that Cd is taken up in the GIT, at least in part, by a similar pathway as Ca(2+), principally that elevated dietary Ca(2+) reduces Cd binding and uptake. Overall our study reveals that metal pre-exposure via water and diet can alter uptake kinetics of Cu and Cd at the gill and/or the gut.     

Assessment of PCBs,heavy metals (Cd,Co, Ni,Pb), mercury and methyl mercury content in four fish commonly consumed in Iran

Coastal waters act as nurseries for various fish species and have been recognized as essential fish habitat. In this study, concentrations of PCB 16, PCB 44, heavy metals Cd, Co, Ni, Pb, mercury (Hg) and methyl Mercury (MMHg) were determined in commercially valuable fish from Khuzestan Shore, northwest of the Persian Gulf. It was also our intention to evaluate potential risks to human health associated with seafood consumption. The results indicated that the concentration of heavy metals in the fish were different among the tissue and species. Generally, liver and skin showed higher metal concentrations than muscle. The results confirmed that the concentration of heavy metal in fish strongly affected by habitat and feeding habitats. The results of this study showed heavy metals concentrations in different food habitats increase in the following order benthic omnivorous fish<zooplanktivores fish<phytoplanktivores fish<piscivores fish. Also, the comparison indicated that benthic species (E. orientalis, O. ruber) were more contaminated than pelagic species (L. abu and P. erumei). The fish species studied had mean concentration lower than all standards, expect Ni and Cd in E. orientalis and Pb in O. ruber. Therefore, the concentration of pollutants in edible part of fish species did not exceed the permissible limits proposed by FAO (1983), WHO (1996), FAD (2001) and are suitable human health.     

Spatial patterns of mercury in biota of Adirondack, New York lakes

We studied the spatial distribution patterns of mercury (Hg) in lake water, littoral sediments, zooplankton, crayfish, fish, and common loons in 44 lakes of the Adirondacks of New York State, USA, a region that has been characterized as a “biological Hg hotspot”. Our study confirmed this pattern, finding that a substantial fraction of the lakes studied had fish and loon samples exceeding established criteria for human and wildlife health. Factors accounting for the spatial variability of Hg in lake water and biota were lake chemistry (pH, acid neutralizing capacity (ANC), percent carbon in sediments), biology (taxa presence, trophic status) and landscape characteristics (land cover class, lake elevation). Hg concentrations in zooplankton, fish and common loons were negatively associated with the lake water acid-base status (pH, ANC). Bioaccumulation factors (BAF) for methyl Hg (MeHg) increased from crayfish (mean log₁₀ BAF = 5.7), to zooplankton (5.9), to prey fish (6.2), to larger fish (6.3), to common loons (7.2). MeHg BAF values in zooplankton, crayfish, and fish (yellow perch equivalent) all increased with increasing lake elevation. Our findings support the hypothesis that bioaccumulation of MeHg at the base of the food chain is an important controller of Hg concentrations in taxa at higher trophic levels. The characteristics of Adirondack lake-watersheds (sensitivity to acidic deposition; significant forest and wetland land cover; and low nutrient inputs) contribute to elevated Hg concentrations in aquatic biota.     

Mercury in Freshwater Fish of Northeast North America – A Geographic Perspective Based on Fish Tissue Monitoring Databases

As part of an initiative to assemble and synthesize mercury (Hg) data from environmental matrices across northeastern North America, we analyzed a large dataset comprised of 15,305 records of fish tissue Hg data from 24 studies from New York State to Newfoundland. These data were summarized to provide mean Hg concentrations for 40 fish species and associated families. Detailed analyses were carried out using data for 13 species. Hg in fishes varied by geographic area, waterbody type, and waterbody. The four species with the highest mean Hg concentrations were muskellunge (Esox masquinongy), walleye (Sander vitreus), white perch (Morone americana), and northern pike (Esox luscius). Several species displayed elevated Hg concentrations in reservoirs, relative to lakes and rivers. Normalized deviations from mean tissue levels for yellow perch (Perca flavescens) and brook trout (Salvelinus fontinalis) were mapped, illustrating how Hg concentrations in these species varied across northeastern North America. Certain geographic regions showed generally below or above-average Hg concentrations in fish, while significant heterogeneity was evident across the landscape. The proportion of waterbodies exhibiting exceedances of USEPAs criterion for fish methylmercury ranged from 14% for standard-length brook trout fillets to 42% for standard-length yellow perch fillets. A preliminary correlation analysis showed that fish Hg concentrations were related to waterbody acidity and watershed size.     

Heavy metals levels in fish from aquaculture farms and risk assessment in Lhasa,Tibetan Autonomous Region of China

Fish is consumed as a common food by humans due to its nutritional and therapeutic benefits. However, they can accumulate toxic chemicals (such as heavy metals, persistent organic pollutants) from water and food chain. Very few studies have been investigated on heavy metal contents in fish from Tibetan Autonomous Region of China. In order to study heavy metals levels in fish from aquaculture farms and evaluate the risk that human consume fish in this area, we collected four types of aquaculture fish species (6 big-head carps, 5 grass carps, 5 carps and 5 tilapias) from fisheries around Lhasa city in this study. 9 heavy metals (Cr, As, Cd, Pb, Cu, Ba, Co, Mn and V) in different tissues of fish were determined by an inductively coupled plasma mass spectrometer. Cr, Ba, Co, Mn and V could easily accumulate in the gill, and Cu was detected in the hearts of all the fishes. Toxic metal (As, Cd and Pb) contents were higher in the liver than those in other tissues, heavy metal levels were the lowest in the muscle among all tissues. Most of heavy metal concentrations in the tilapia tissues were higher than those in other fish tissues, especially arsenic. Arsenic content in the tilapia samples was ~2–4 times higher than the maximum levels (MLs) of contaminants in the national standard, and other metals were all lower than the MLs. Compared the estimated daily intake of heavy metals through fish consumption with tolerable daily intakes recommended by FAO, the metals daily intake of As, Cd and Pb from fish consumption might not pose serious health risk to the local inhabitants. It is therefore necessary to determine the dose level for human, which is considered to be taken daily over a lifetime without adverse effects.     

Toxicological effects and reproductive impairments in female perch (Perca fluviatilis) exposed to leachate from Swedish refuse dumps

We have previously found that leachate from a Swedish refuse dump caused toxicological effects, including endocrine disruption and reproductive failures, in feral female perch (Perca fluviatilis) from Molnbyggen and in brook trout (Salvelinus fontinalis) from Vadb?cken. This raised concerns that leachate-induced toxicity might affect fish in other leachate-contaminated lakes. This study looks at female perch from three different regions in Sweden, focusing on toxicological biomarkers (skin lesions, liver-somatic index (LSI), ethoxyresorufin O-deethylase (EROD) activity and DNA adducts) and reproductive biomarkers (number of mature females, gonadosomatic index (GSI), aromatase (P450arom), progesterone, 17alpha-hydroxyprogesterone (17alpha-OHP), testosterone (T) and 17beta-estradiol (E2)). Five out of seven contaminated locations had lower numbers of mature females and most of them exhibited higher frequencies of fin erosion relative to their comparable reference sites. Females from Lake Nedre V?ttern exhibited these effects, as well as body sores, high EROD activity, high levels of DNA adducts in the liver and the intestinal mucosa, low GSI and low plasma levels of T and E2, similar to the anti-estrogenic effects earlier found in SM perch from Molnbyggen in 1997 and in brook trout from Vadb?cken. No effects on LSI, GSI, aromatase, or circulating steroids were found in mature females from Molnbyggen in this study. This indicated less leachate-contamination, but low numbers of mature females in Lake Siljan, at the sewage treatment plant which now processes the leachate that earlier contaminated Molnbyggen and Vadb?cken, suggested insufficient sewage treatment at this site. All females in Lake Simshyttsj?n were mature, and their high GSI and LSI, low EROD activity, high level of 17alpha-OHP and low level of T, suggest an estrogenic rather than an anti-estrogenic effect. The results show that our earlier findings in Molnbyggen and Vadb?cken are not common, but neither are they unique. This study also shows that refuse dumps should be considered as potential point-sources for environmental pollutants, and that uncontrolled leachate-contamination of lakes and freshwater reservoirs could be a serious environmental hazard for both wildlife and humans.     

Bioaccumulation and the effects of organochlorine pesticides, PAH and heavy metals in the Eel (Anguilla anguilla) at the Camargue Nature Reserve, France

Pesticides (organochlorines-OC), polycyclic aromatic hydrocarbons (PAH) and heavy metals are toxic to fish and may be taken in through gills, skin and contaminated foods. Here we measure concentrations of OC, PAH and heavy metals, and their effects in the eel Anguilla anguilla from three locations in the Camargue Reserve in southern France. The Camargue Biosphere Reserve is the largest coastal wetland in Western Europe, and A. anguilla is a common predator at the top of the food chain. Livers and spleens were analyzed for histopathological, chemical and organo-somatic (HSI and SSI) effects. Gill, liver and spleen samples were collected for histopathological studies. Livers and muscles were sampled for metabolic parameters and persistent organic pollutant analysis. Total lipids were estimated by spectrophotometry and lipid-free residues were used in protein and glycogen analysis. OC pesticides were extracted from lipids of muscles and livers, analyzed by gas chromatography, and PAH from bile were analyzed by fixed wavelength fluorescence spectrofluorimetry. Heavy metals were measured by inductively coupled plasma with optical or with mass spectrometers. High concentrations of contaminants were found in eel tissues. La Capelière had the greatest OC and PAH concentrations; unexpected lesions in gills, livers and spleens were more common at the other sites. Liver and spleen tumors and lipidosis in livers were associated with chronic, and gill lesions with acute exposure. High pesticide and PAH concentrations and lesions in eels from the Camargue reserve demonstrate the contamination of the area. A more complete study in the Camargue reserve is necessary to better understand the impact on wildlife and humans. Also, this study suggests that eel biology must be better understood before continued use of this species as a biomonitor of polluted areas.     

The Bioaccumulation of Mercury in Aquatic Organisms from Two Similar Lakes with Differing pH

Two small drainage lakes of similar surface area (0.4–0.6 km ² ) and depth, and situated in close proximity to one another (about 9 km apart) in the Muskoka-Haliburton district of rural Ontario, Canada were chosen to investigate the effects of differing pH on Hg accumulation in fish and other biota. Blue Chalk Lake is circumneutral (pH = 6.3–6.9) with an average dissolved organic carbon (DOC) concentration of 2.69 mg/L; Plastic Lake is acidic (pH = 5.2–5.6) with a similar DOC level (2.72 mg/L). Neither lake is an impoundment, and neither receives inputs from point-source urban or industrial waste emissions. Surficial (top 4 cm) sediments and various aquatic biota, including crayfish (Orconectes virilis)], and 5 species of fish [brown bullhead (Ictalurus nebulosus), creek chub (Semotilus atromaculatus), pumpkinseed sunfish (Lepomis gibbosus), yellow perch (Perca flavenscens) and rock bass (Ambloplites rupestris)] were sampled for Hg analysis. Only creek chub and pumpkinseed occurred in both lakes. Significant size (length) vs. Hg-concentration relationships were observed for brown bullhead, pumpkinseed, yellow perch and rock bass, but not for crayfish nor for creek chub in either lake. Rock bass had the highest mean Hg concentration (1.02 ± 0.98 g/g dry wt.). Pumpkinseed from Plastic Lake had the highest overall rate of accumulation with increasing size. Several individual pumpkinseed and rock bass sampled from the acidic Plastic Lake had Hg concentrations equal to or greater than levels reported to be hazardous to breeding piscivorous birds, such as common loons (Gavia immer), whereas no fish from Blue Chalk approached this threshold (0.3 g/g wet wt). This study illustrates the importance of within-lake parameters, particularly pH, and species trophic level, in determining Hg accumulation in fish in lakes of similar size that receive similar atmospheric Hg inputs.