Biomarker investigations in adult female perch (Perca fluviatilis) from industrialised areas in northern Sweden in 2003.

Since the new millennium, a notion has developed in certain parts of society that environmental pollutants and their associated effects are under control. The primary objective of this investigation, performed in 2003, was to test whether this was actually the case in an industrialised region in the County of Västernorrland in northern Sweden with well-documented environmental pollution from past and present activities. This was performed by measuring a moderate battery of simple biomarkers in adult female perch at several stations. The point sources included sewage-treatment plants, pulp and paper mills, as well as other industries. The biomarkers included growth, somatic indices, gonad maturation status, gonad pigmentation, fin erosion, skin ulcers, and ethoxyresorufin-O-deethylase (EROD) activity in the liver. The results showed that the environmental pollutants and their associated effects were not under control. In fact, the health of the perch was impaired at all of the polluted stations. Many responses were unspecific with respect to underlying cause, whereas some effects on EROD activity and gonad maturation status were attributed to historical creosote pollution and current kraft pulp mill effluents, respectively. The data presented may also be used as reference values for future investigations of health effects in perch.

Wild birds of declining European species are dying from a thiamine deficiency syndrome.

Wild birds of several species are dying in large numbers from an idiopathic paralytic disease in the Baltic Sea area. Here, we demonstrate strong relationships between this disease, breeding failure, and thiamine (vitamin B(1)) deficiency in eggs, pulli, and full-grown individuals. Thiamine is essential for vertebrates, and its diphosphorylated form functions as a cofactor for several life sustaining enzymes, whereas the triphosphorylated form is necessary for the functioning of neuronal membranes. Paralyzed individuals were remedied by thiamine treatment. Moreover, thiamine deficiency and detrimental effects on thiamine-dependent enzymes were demonstrated in the yolk, liver, and brain. We propose that the mortality and breeding failure are part of a thiamine deficiency syndrome, which may have contributed significantly to declines in many bird populations during the last decades.

Genotoxicity in herring gulls (Larus argentatus) in Sweden and Iceland.

Adult and young herring gulls (Larus argentatus) in Sweden and Iceland were investigated with respect to DNA adducts, analysed with the nuclease-P1 version of the (32)P-postlabelling method, and micronucleated erythrocytes. Three important aims were: (1) to estimate the degree of exposure to genotoxic environmental pollutants in the Baltic Sea area and Iceland, (2) to evaluate the utility of the investigated biomarkers in birds, and (3) to investigate if there was any relationship between genotoxic effects and thiamine deficiency. The results demonstrate that both Swedish and Icelandic herring gulls are exposed to genotoxic pollution. Urban specimens have higher levels of DNA adducts than rural specimens, but background exposure to genotoxic environmental pollutants, such as PAHs, is also significant. In the herring gull the general level of DNA adducts in the liver seems to be higher than in fish. DNA adducts were most abundant in the liver, followed by the kidney, intestinal mucosa, and whole blood, in decreasing order. The frequency of micronucleated erythrocytes was probably slightly elevated in all the investigated sites, reflecting a significant background exposure. The level of DNA adducts was unrelated to the frequency of micronucleated erythrocytes, and both these variables were unrelated to symptoms of thiamine deficiency. The investigation confirmed the utility of DNA adducts, and probably also micronucleated erythrocytes, as biomarkers of genotoxicity in birds.

Severe thiamine deficiency in eastern Baltic cod (Gadus morhua).

The eastern Baltic cod (Gadus morhua) population has been decreasing in the Baltic Sea for at least 30 years. Condition indices of the Baltic cod have decreased, and previous studies have suggested that this might be due to overfishing, predation, lower dissolved oxygen or changes in salinity. However, numerous studies from the Baltic Sea have demonstrated an ongoing thiamine deficiency in several animal classes, both invertebrates and vertebrates. The thiamine status of the eastern Baltic cod was investigated to determine if thiamine deficiency might be a factor in ongoing population declines. Thiamine concentrations were determined by chemical analyses of thiamine, thiamine monophosphate and thiamine diphosphate (combined SumT) in the liver using high performance liquid chromatography. Biochemical analyses measured the activity of the thiamine diphosphate-dependent enzyme transketolase to determine the proportion of apoenzymes in both liver and brain tissue. These biochemical analyses showed that 77% of the cod were thiamine deficient in the liver, of which 13% had a severe thiamine deficiency (i.e. 25% transketolase enzymes lacked thiamine diphosphate). The brain tissue of 77% of the cod showed thiamine deficiency, of which 64% showed severe thiamine deficiency. The thiamine deficiency biomarkers were investigated to find correlations to different biological parameters, such as length, weight, otolith weight, age (annuli counting) and different organ weights. The results suggested that thiamine deficiency increased with age. The SumT concentration ranged between 2.4-24 nmol/g in the liver, where the specimens with heavier otoliths had lower values of SumT (P = 0.0031). Of the cod sampled, only 2% of the specimens had a Fulton's condition factor indicating a healthy specimen, and 49% had a condition factor below 0.8, indicating poor health status. These results, showing a severe thiamine deficiency in eastern Baltic cod from the only known area where spawning presently occurs for this species, are of grave concern.

Water column monitoring near oil installations in the North Sea 2001-2004.

Fisheries have been vital to coastal communities around the North Sea for centuries, but this semi-enclosed sea also receives large amounts of waste. It is therefore important to monitor and control inputs of contaminants into the North Sea. Inputs of effluents from offshore oil and gas production platforms (produced water) in the Norwegian sector have been monitored through an integrated chemical and biological effects programme since 2001. The programme has used caged Atlantic cod and blue mussels. PAH tissue residues in blue mussels and PAH bile metabolites in cod have confirmed exposure to effluents, but there was variation between years. Results for a range of biological effects methods reflected exposure gradients and indicated that exposure levels were low and caused minor environmental impact at the deployment locations. There is a need to develop methods that are sufficiently sensitive to components in produced water at levels found in marine ecosystems.

Thiamine deficiency impairs common eider (Somateria mollissima) reproduction in the field.

The Baltic Sea population of the common eider (Somateria mollissima) has declined dramatically during the last two decades. Recently, widespread episodic thiamine (vitamin B1) deficiency has been demonstrated in feral birds and suggested to contribute significantly to declining populations. Here we show that the decline of the common eider population in the Baltic Sea is paralleled by high mortality of the pulli a few days after hatch, owing to thiamine deficiency and probably also thereby associated abnormal behaviour resulting in high gull predation. An experiment with artificially incubated common eider eggs collected in the field revealed that thiamine treatment of pulli had a therapeutic effect on the thiamine status of the brain and prevented death. The mortality was 53% in untreated specimens, whereas it was only 7% in thiamine treated specimens. Inability to dive was also linked to brain damage typical for thiamine deficiency. Our results demonstrate how thiamine deficiency causes a range of symptoms in the common eider pulli, as well as massive die-offs a few days after hatch, which probably are the major explanation of the recent dramatic population declines.

May organic pollutants affect fish populations in the North Sea?

The North Sea is a highly productive area with large fish populations that have been extensively harvested over the past century. North Sea fisheries remain important to the surrounding countries despite declining fish stocks over the past decades. The main reason for declining fish stocks is nearly certainly overfishing, but other environmental pressures also affect fish populations, such as eutrophication, climate change, and exposure to metals and organic pollutants, including polyaromatic hydrocarbons (PAHs), alkylphenols, and organochlorine compounds. There are three main sources of organic pollutants in the North Sea: atmospheric, land-based sources, and inputs from offshore gas and oil installations. All three sources contribute to elevated concentrations of organic pollutants in the North Sea compared to the Norwegian Sea. There is evidence that chlorinated organic contaminants were present in sufficiently high concentrations in the southern North Sea two decades ago, to alter embryonal development in fish. The results from extensive, long-term monitoring programs show that some diseases decreased whereas other increased in the southern North Sea and that, among other factors, contaminants may play a role in the temporal changes recorded in disease prevalence. Recent studies demonstrated that components in offshore effluents may affect fish reproduction and that tissues of fish near oil rigs are structurally different to tissues of fish from reference areas. Data on effluents from offshore activities have recently become available through an international workshop (BECPELAG) and follow-up studies.

Sex steroids in the female zebrafish (Danio rerio). Effects of cyproterone acetate and leachate-contaminated sediment extract.

In Molnbyggen, a leachate-contaminated lake in Sweden, effects on the reproductive system of perch included a decreased frequency of sexually mature female perch, reduced gonadosomatic index and decreased plasma levels of androstenedione and testosterone, but the contaminants responsible for these effects have not yet been identified. A biomarker-directed fractionation approach could be used to narrow the search for the compound(s) responsible for the adverse effects in Molnbyggen female perch. Thus, it is important to develop and test a suitable biomarker, which can be used in this type of approach. We evaluated if decreased concentrations of sex steroids could work as an in vivo end-point in female zebrafish fed an organic extract of bottom sediments from Molnbyggen. The responsiveness of zebrafish to endocrine alteration was evaluated using a positive control substance, cyproterone acetate (CA), which is known to inhibit steroid biosynthesis. After the 21-day exposure period the concentrations of testosterone (T) and estradiol (E2) were successfully determined by HRGC/HRMS in whole-body homogenates of individual fish. Median T concentrations were 1.7pmol/g fish in controls and were decreased after exposure both to CA (0.55pmol/g fish) and Molnbyggen sediment extract (1.2-1.3pmol/g fish). Median E2 concentrations were 5.3pmol/g fish in controls and were decreased after CA exposure (2.3pmol/g fish) and after exposure to Molnbyggen sediment extract (4.0-4.5pmol/g fish). This suggests that sex steroid concentrations in zebrafish are responsive to endocrine alteration and indicates that compounds with endocrine altering potency are present in Molnbyggen sediments.

Long-term monitoring of the health status of female perch (Perca fluviatilis) in the Baltic Sea shows decreased gonad weight and increased hepatic EROD activity.

Annual investigations of the health status of female perch (Perca fluviatilis) were performed during 8-13 years in order to detect long-term, large-scale changes in the Baltic Sea. These background data are also meant to be used as baselines in recipient investigations at various point sources in the Baltic Sea. Fish were sampled at three coastal sites in Sweden: two in the Baltic Proper (since 1988) and one in the Bothnian Bay (since 1993). In all, 19 biochemical, physiological and histopathological variables were measured. By reflecting central functions of life, such as red blood cell functions, immune defence, liver function, biotransformation processes, intermediary metabolism, ion balance, and reproduction, the selected variables give a good picture of the health status of the fish. The most important observations were strong trends towards decreased gonadosomatic index (relative gonad size) and increased hepatic EROD activity in female perch in the Baltic Proper. Most of the other variables varied little between the years. The reduced gonad size and the EROD induction indicate that factors in the environment, e.g. the occurrence of pollutants, affect important physiological functions, such as reproduction and biotransformation processes, in fish even in a reference area in the Baltic Proper. It is urgent to make further studies in order to identify which pollutant(s) or other possible cause(s) are responsible for the observed biological effects.

Steroid biosynthetic enzyme activities in leachate-exposed female perch (Perca fluviatilis) as biomarkers for endocrine disruption.

Studies have shown that adult female perch in a freshwater lake, Molnbyggen, Sweden, have a reproductive disorder caused by unidentified endocrine disrupting compounds (EDCs) leaching from a local refuse dump. The adverse effects include shallow open sores, low ratio of sexually mature individuals, low gonadosomatic index and low circulating levels of androgens. We hypothesised that the low androgen levels could be a result of impaired production and/or stimulated excretion of androgens by EDCs. From October 2000 to November 2001, at time-points important in the perch reproductive cycle, adult female perch were collected in Molnbyggen and in the reference lake, Djursjön. The activities of three key enzymes in androgen biosynthesis: 17alpha-hydroxylase (17OHlase), 17,20-lyase (lyase) and 17beta-hydroxysteroid dehydrogenase (17betaHSD) were determined in head kidney or ovary. The relationship between enzyme activities and plasma steroid concentrations was examined. Ovarian histopathology and the determination of brain aromatase activity were also included in the study. Similar 17OHlase, 17betaHSD and aromatase activities were found in Molnbyggen females and reference fish throughout the year. Head kidney 17OHlase showed a positive correlation to cortisol levels (r=0.754; p<0.001) but not to androgen levels. Molnbyggen females exhibited lower ovarian lyase activity during vitellogenesis than reference fish. Atretic oocytes were on most occasions more frequent in sexually immature than in sexually mature females. The results suggest that neither 17OHlase, 17betaHSD nor aromatase is the target for EDCs disrupting the androgen homeostasis of exposed female perch. Further investigation is needed to establish the role of decreased ovarian lyase activity in endocrine homeostasis, but the possibility of increased excretion of androgens should also be examined.

Basic physiological biomarkers in adult female perch (Perca fluviatilis) in a chronically polluted gradient in the Stockholm recipient (Sweden).

By measuring a battery of basic physiological biomarkers and the concentration of SigmaDDT in adult female perch (Perca fluviatilis), an assumed aquatic pollution gradient was confirmed, with the city of Stockholm (Sweden) as a point source of anthropogenic substances. The investigation included an upstream gradient, westwards through Lake Mälaren (46 km), and a downstream gradient, eastwards through the Stockholm archipelago (84 km). The results indicated a severe pollution situation in central Stockholm, with poor health status of the perch: retarded growth, increased frequency of sexually immature females, low gonadosomatic index, and disturbed visceral fat metabolism. SigmaDDT, measured as a pollution indicator, was 10-28 times higher than the background in perch from the Baltic Proper. Besides the main gradient other sources of pollution also influenced the response pattern of the measured biomarkers. In particular, there were strong indications of pollution coming from the Baltic Sea.

Biomarker responses as indication of contaminant effects in blue mussel (Mytilus edulis) and female eelpout (Zoarces viviparus) from the southwestern Baltic Sea.

During a field study performed in spring and autumn 2001 and 2002, blue mussels (Mytilus edulis) and female eelpout (Zoarces viviparus) were collected at three locations in the Wismar Bay (Baltic Sea), and several biomarkers of contaminant effects were analysed. Besides seasonal and inter-annual variations, biomarker signals were most pronounced at the location closest to Wismar Harbour (Wendorf) in both species. Lysosomal membrane stability (LMS) was lowest and acetylcholinesterase activity (AChE) was significantly reduced. Frequency of micronuclei (MN) was significantly higher (in blue mussels), indicating mutagenic effects. In eelpout elevated levels of DNA adducts, EROD induction and PAH-metabolites were measured. Metallothionein (MT), biomarker for trace metal exposure, showed a gradient only in spring. Organochlorine contaminant analyses (PCBs, DDTs) corresponded to the observed biomarker levels. The results obtained clearly demonstrate pollution effects in the southwestern Baltic Sea. Moreover, they show that a multibiomarker approach is also applicable in a brackish water environment.

Biochemical biomarkers in adult female perch (Perca fluviatilis) in a chronically polluted gradient in the Stockholm recipient (Sweden).

A battery of biochemical biomarkers and the SigmaPCB concentration in adult female perch (Perca fluviatilis) verified an aquatic pollution gradient with the city of Stockholm (Sweden) as a point source of anthropogenic substances. The investigation included both an upstream gradient, 46 km westwards through Lake Mälaren, and a downstream gradient, 84 km eastwards through the Stockholm archipelago. Besides the main gradient from Stockholm, there were strong indications of pollution coming from the Baltic Sea. The results indicated a severe pollution situation in central Stockholm, with poor health status of the perch, characterised by increased specific EROD activity in the liver, increased liver EROD somatic index, decreased AChE activity in the muscle, increased amount of DNA adducts in the liver, and a high concentration of biliary 1-pyrenol. In addition, laboratory exposure to common EROD inducers elicited an abnormal response, suggestive of chronic intoxication.

Widespread episodic thiamine deficiency in Northern Hemisphere wildlife.

Many wildlife populations are declining at rates higher than can be explained by known threats to biodiversity. Recently, thiamine (vitamin B1) deficiency has emerged as a possible contributing cause. Here, thiamine status was systematically investigated in three animal classes: bivalves, ray-finned fishes, and birds. Thiamine diphosphate is required as a cofactor in at least five life-sustaining enzymes that are required for basic cellular metabolism. Analysis of different phosphorylated forms of thiamine, as well as of activities and amount of holoenzyme and apoenzyme forms of thiamine-dependent enzymes, revealed episodically occurring thiamine deficiency in all three animal classes. These biochemical effects were also linked to secondary effects on growth, condition, liver size, blood chemistry and composition, histopathology, swimming behaviour and endurance, parasite infestation, and reproduction. It is unlikely that the thiamine deficiency is caused by impaired phosphorylation within the cells. Rather, the results point towards insufficient amounts of thiamine in the food. By investigating a large geographic area, by extending the focus from lethal to sublethal thiamine deficiency, and by linking biochemical alterations to secondary effects, we demonstrate that the problem of thiamine deficiency is considerably more widespread and severe than previously reported.

Bioinformatic and enzymatic characterization of the MAPEG superfamily.

The membrane associated proteins in eicosanoid and glutathione metabolism (MAPEG) superfamily includes structurally related membrane proteins with diverse functions of widespread origin. A total of 136 proteins belonging to the MAPEG superfamily were found in database and genome screenings. The members were found in prokaryotes and eukaryotes, but not in any archaeal organism. Multiple sequence alignments and calculations of evolutionary trees revealed a clear subdivision of the eukaryotic MAPEG members, corresponding to the six families of microsomal glutathione transferases (MGST) 1, 2 and 3, leukotriene C4 synthase (LTC4), 5-lipoxygenase activating protein (FLAP), and prostaglandin E synthase. Prokaryotes contain at least two distinct potential ancestral subfamilies, of which one is unique, whereas the other most closely resembles enzymes that belong to the MGST2/FLAP/LTC4 synthase families. The insect members are most similar to MGST1/prostaglandin E synthase. With the new data available, we observe that fish enzymes are present in all six families, showing an early origin for MAPEG family differentiation. Thus, the evolutionary origins and relationships of the MAPEG superfamily can be defined, including distinct sequence patterns characteristic for each of the subfamilies. We have further investigated and functionally characterized representative gene products from Escherichia coli, Synechocystis sp., Arabidopsis thaliana and Drosophila melanogaster, and the fish liver enzyme, purified from pike (Esox lucius). Protein overexpression and enzyme activity analysis demonstrated that all proteins catalyzed the conjugation of 1-chloro-2,4-dinitrobenzene with reduced glutathione. The E. coli protein displayed glutathione transferase activity of 0.11 micromol.min(-1).mg(-1) in the membrane fraction from bacteria overexpressing the protein. Partial purification of the Synechocystis sp. protein yielded an enzyme of the expected molecular mass and an N-terminal amino acid sequence that was at least 50% pure, with a specific activity towards 1-chloro-2,4-dinitrobenzene of 11 micromol.min(-1).mg(-1). Yeast microsomes expressing the Arabidopsis enzyme showed an activity of 0.02 micromol.min(-1).mg(-1), whereas the Drosophila enzyme expressed in E. coli was highly active at 3.6 micromol.min(-1).mg(-1). The purified pike enzyme is the most active MGST described so far with a specific activity of 285 micromol.min(-1).mg(-1). Drosophila and pike enzymes also displayed glutathione peroxidase activity towards cumene hydroperoxide (0.4 and 2.2 micromol.min(-1).mg(-1), respectively). Glutathione transferase activity can thus be regarded as a common denominator for a majority of MAPEG members throughout the kingdoms of life whereas glutathione peroxidase activity occurs in representatives from the MGST1, 2 and 3 and PGES subfamilies.

A bio-effect directed fractionation study for toxicological and chemical characterization of organic compounds in bottom sediment.

The major aim of this study was to characterize toxic organic compounds in bottom sediments from a PCB polluted bay. To overcome difficulties in pinpointing toxicants in complex environmental samples we applied a bio-effect directed (BED) fractionation approach and investigated the relationships between aromaticity, teratogenicity, and aryl hydrocarbon receptor (AhR) mediated toxicity. Hepatic ethoxyresorufin O-deethylase (EROD) activities and malformations were investigated in rainbow trout (Oncorhynchus mykiss) larvae exposed by injecting sediment extract and fractions (separated by their degree of aromaticity) thereof into newly fertilized eggs. Our results imply that non-additive effects get more pronounced the more complex the exposure. The fraction mainly composed of dicyclic aromatic compounds (DACs), including PCBs, was surprisingly less teratogenic than the fraction mainly composed of polycyclic aromatic compounds (PACs). A major part of the latter potential was isolated in a subfraction mainly composed of three- and four-ring compounds (including alkylated and sulphur-heterocyclic compounds). Though no clear relationship between aromaticity and EROD induction was observed, both the DAC- and the PAC-fractions contributed equally to the EROD induction potential. A major part of the PAC-fraction's induction potential came from a subfraction containing compounds with more than five rings. No clear relationship between teratogenicity and EROD induction was observed, underlining the need for a battery of biomarkers in estimating environmental risk. Two specific malformations not previously described in literature-asymmetric yolk sac and fin edema-could be tracked through the fractionation steps, suggesting that this BED-fractionation strategy is a reliable tool for pinpointing toxic compounds in the environment.

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 Vadbäcken. 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 Vättern 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 Vadbäcken. 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 Vadbäcken, suggested insufficient sewage treatment at this site. All females in Lake Simshyttsjön 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 Vadbäcken 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.

Reproductive status in female perch (Perca fluviatilis) outside a sewage treatment plant processing leachate from a refuse dump.

Reproductive failure and endocrine disruption in female perch (Perca fluviatilis) and female brook trout (Salvelinus fontinalis), naturally exposed to toxic leachate from a municipal refuse dump, has raised concerns about the reproductive status in female fish outside the sewage treatment plant (STP), which now treats the same leachate. Female perch from the receiving water, Lake Siljan, were therefore sampled in a gradient from the STP in Fornby and Osterviken and compared with reference females from Isunda or Solleron. A high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) technique enabled the analysis of circulating steroids in blood plasma: the sex steroids progesterone (P), 17alpha-hydroxyprogesterone (17alpha-OHP), androstenedione (A), testosterone (T), estrone (E1), and 17beta-oestradiol (E2), the maturation-inducing hormone (MIH) 17alpha,20beta-dihydroxy-4-pregnen-3-one (17alpha,20beta-P), and the glucocorticoids 11-deoxycortisol (11-DC) and cortisol (C). Body and organ measurements, ratio of sexually mature (SM) females, and frequencies of body lesions, were also recorded. The percentages of SM females found in Fornby on Oct 23 (83.8%) and in Osterviken on May 14 (54.0%) were lower compared with Isunda (100%). The lack of differences in gonadosomatic index (GSI) and liver-somatic index (LSI) indicated a normal vitellogenesis in SM females from Fornby and Osterviken. No differences in circulating levels of steroids were observed between the sites, except at the time of spawning, when elevated P and 17alpha-OHP levels in females from Osterviken indicated a steroidogenic shift from the synthesis of sex steroids towards the production of the MIH 17alpha,20beta-P. The significant peak-levels of both 17alpha,20beta-P and 11-DC in female perch from Osterviken at the same time suggest that both are involved in controlling final oocyte maturation in perch. The elevated levels of androgens (A and T) in females caught on the same occasion in Fornby implied that these females were at an earlier stage of oocyte maturation, prior to the steroidogenic shift towards MIH-production. This study confirms the results of an earlier study revealing low numbers of SM female perch outside the STP in Fornby. The lack of associated effects on organ indexes and circulating levels of steroids does not indicate exposure to endocrine disrupting substances (EDSs) from the treated sewage. The consistently high numbers of SM females in the northern part of Siljan suggest, however, that natural factors are not responsible for the reproductive failures in the southern part of the lake.

Effects of dredging in Göteborg harbor, Sweden, assessed by biomarkers in eelpout (Zoarces viviparus).

We used a battery of biomarkers in fish to study the effects of the extensive dredging in Göteborg harbor situated at the river Göta alv estuary, Sweden. Eelpout (Zoarces viviparus) were sampled along a gradient into Göteborg harbor, both before and during the dredging. Biomarker responses in the eelpout before the dredging already indicated that fish in Göteborg harbor are chronically affected by pollutants under normal conditions compared to those in a reference area. However, the results during the dredging activities clearly show that fish were even more affected by remobilized pollutants. Elevated ethoxyresorufin-O-deethylase activities and cytochrome P4501A levels indicated exposure to polycyclic aromatic hydrocarbons. Elevated metallothionein gene expression indicated an increase in metal exposure. An increase in general cell toxicity, measured as a decrease in lysosomal membrane stability, as well as effects on the immune system also could be observed in eelpout sampled during the dredging. The results also suggest that dredging activities in the Göta alv estuary can affect larger parts of the Swedish western coast than originally anticipated. The present study demonstrates that the application of a set of biomarkers is a useful approach in monitoring the impact of anthropogenic activities on aquatic environments.

The distribution and relative toxic potential of organic chemicals in a PCB contaminated bay.

For reliable monitoring of environmental improvement, the PCB contaminated bay Orserumsviken on Sweden's Baltic coast was investigated prior to remediation. We examined PCB congener patterns and the relative toxic potential of PCBs in extracts of three matrices: bottom sediment, settling particulate matter and the dissolved phase (obtained from semi-permeable membrane devices). Congener patterns were similar in all matrices. Three fractions were isolated from the extracts: (1) aliphatic and monocyclic aromatic compounds (MAC-fraction), (2) dicyclic aromatic compounds (DAC-fraction), including PCBs, and (3) polycyclic aromatic compounds (PAC-fraction), including PAHs. Total extracts and fractions were injected into newly fertilised rainbow trout eggs. At larval stage, hepatic EROD activities were quantified. Though high, the PCB contamination could explain only an estimated 1-5% of the total EROD induction. The order of EROD induction potential was: total extract > PAC-fraction > DAC-fraction > MAC-fraction in all matrices, suggesting that in Orserumsviken PACs made a larger contribution to the EROD induction potential than PCBs and other DACs.