Spatial variations in biomarkers of Mytilus edulis mussels at four polluted regions spanning the Northern Hemisphere

Characterising Sex-Specific Metabolite Differences in New Zealand Geoduck (Panopea zelandica) Using LC-MS/MS Metabolomics

Geoduck aquaculture is becoming a key component in meeting international market demand, given the natural and regulatory restrictions on wild geoduck supply. Geoduck clams are not sexually dimorphic, making it practically unfeasible to distinguish between males and females prior to a spawning event. To facilitate increased production of geoduck, a better understanding of reproductive biology and associated targeted bio-markers is required. In this study, metabolomics was utilised as a research tool to distinguish between metabolites related to male and female New Zealand geoduck (Panopea zelandica), gill and muscle samples collected from broodstock individuals housed in an experimental hatchery. A total of 17 metabolites were detected, showing significant differences between sexes. The findings indicate that metabolites associated with lipid biosynthesis were increased in female clams to support reproductive functions. An increase in carbohydrate-linked metabolic pathways was detected in male geoduck, arguably to sustain sperm production. Taurine has been reported as a biomarker to distinguish between male and female bivalves in other studies and is confirmed within this study, with significant elevation in male adductor muscle tissue. Moreover, male geoduck had increased purine and pyrimidine biosynthesis, supporting energy needs. This study provides useful sex biomarkers for future breeding strategies of P. zelandica.

Stress responses of bivalve mollusc Unio tumidus from two areas to ibuprofen, microplastic and their mixture

Even though bivalve molluscs are recognized as bioindicators of freshwater quality, their responses to multiple stressors are unpredictable. This study aims to elucidate the inter-population peculiarities of the effect in the sub-chronic environmentally relevant exposure to novel contaminants. The specimens of Unio tumidus from reference (Pr) and contaminated (Ct) areas were treated with ibuprofen (IBU, 0.8 µg L^-1), microplastic (MP, 1.0 mg L^-1, size 0.1-0.5 mm), or their combination (Mix) for 14 days. Untreated mussels (PrC- and CtC-groups) served as controls. The PrC-group had higher levels of antioxidants Mn-SOD, Cu,Zn-SOD, catalase, and cholinesterase (AChE) as well as lesser levels of oxidative lesions (TBARS and protein carbonyls) in digestive glands, indicating lower environmental impact than in the CtC-group. However, lysosomal stability was similar in both control groups. Among antioxidants, Mn-SOD activity was affected most prominently, increasing in all exposed Ct-groups. TBARS level was increased only in PrMP-group compared to responsive control. IBU and Mix enhanced protein carbonyl concentration in the Pr-groups, and decreased it in the Ct-groups. AChE was induced in the CtIBU- and PrMix-groups, and lysosomal integrity increased in the CtIBU and CtMix-groups. Discriminant analyses indicated lesser differences between Pr-groups, demonstrating lower cumulative stress compared to Ct-groups. Generally, the most remarkable response was revealed in the CtIBU-group, and distortion of individual effects was established in combined exposures. The qualification of stress-neutral and stress-positive populations was proposed for Pr- and Ct-populations correspondingly. Inter-site peculiarities must be taken into consideration when the environmental impact of MP and pharmaceuticals is evaluated.

Improving knowledge on genotoxicity dynamics in somatic and germ cells of crayfish (Procambarus clarkii)

The harmful effects of pesticides can be extended beyond the exposure time scale. Appraisals combining exposure and long-term post-exposure periods appear as an unavoidable approach in pesticide risk assessment, thus allowing a better understanding of the real impact of agrochemicals in non-target organisms. This study aimed to evaluate the progression of genetic damage in somatic and germ tissues of the crayfish Procambarus clarkii, also seeking for gender-specificities, following exposure (7 days) to penoxsulam (23 μg L^-1 ) and a post-exposure (70 days) period. The same approach was applied to the model genotoxicant ethyl methanesulfonate (EMS; 5 mg L^-1 ) as a complementary mean to improve knowledge on genotoxicity dynamics (induction vs. recovery). Penoxsulam induced DNA damage in all tested tissues, disclosing tissue- and gender-specificities, where females showed to be more vulnerable than males in the gills, while males demonstrated higher susceptibility in what concerns internal organs, that is, hepatopancreas and gonad. Crayfish were unable to recover from the DNA damage induced by EMS in gills and hepatopancreas (both genders) as well as in spermatozoa. The genotoxicity in the hepatopancreas was only perceptible in the post-exposure period. Oxidative DNA lesions were identified in hepatopancreas and spermatozoa of EMS-exposed crayfish. The spermatozoa proved to be the most vulnerable cell type. It became clear that the characterization of the genotoxic hazard of a given agent must integrate a complete set of information, addressing different types of DNA damage, tissue- and gender-specificities, as well as a long-term appraisal of temporal progression of damage.

Multi-marker study of the responses of the Unio tumidus from the areas of small and micro hydropower plants at the Dniester River Basin, Ukraine

The impact of the hydropower plants (HPPs) on the aquatic life is expected, but the biochemical markers of ecotoxicity have not been investigated in relation to HPP proximity. The aim of this study was to compare the responses of mollusk Unio tumidus from the small HPP (reservoir (Ku) and downstream of the dam (Kd)) and micro HPP (upstream (Zu) and downstream of the dam (Zd)). In total, 11 indexes (n) from digestive gland, hemocytes (lysosomal integrity), and gonads (alkali-labile phosphates, ALP) were analyzed. The mollusks from the reservoir demonstrate the typical signs of toxic impact: cholinesterase and glutathione depletion, the highest glutathione S-transferase activity, and ratio of extralysosomal cathepsin D compare to all other groups. The specimens from the micro HPP have the highest levels of glutathione (Zd) and lipid peroxidation (Zu) and lesser Cu/Zn-SOD activity (Zu) than other groups. These indications of stressful conditions may derive from the regular oscillations in the water flow regimes at the micro HPP. For both HPPs, the responses of upstream and downstream groups are distinct. The calculated IBR/n (4.17, 3.85, 3.12, and 0.26 for Ku, Kd, Zu, and Zd correspondingly) gives a quantitative basis for the evaluation of environmental impact of HPPs. Graphical abstract .

Monitoring nearshore ecosystem health using Pacific razor clams (Siliqua patula) as an indicator species

An emerging approach to ecosystem monitoring involves the use of physiological biomarker analyses in combination with gene transcription assays. For the first time, we employed these tools to evaluate the Pacific razor clam (Siliqua patula), which is important both economically and ecologically, as a bioindicator species in the northeast Pacific. Our objectives were to (1) develop biomarker and gene transcription assays with which to monitor the health of the Pacific razor clam, (2) acquire baseline biomarker and gene transcription reference ranges for razor clams, (3) assess the relationship between physiological and gene transcription assays and (4) determine if site-level differences were present. Pacific razor clams were collected in July 2015 and 2016 at three sites within each of two national parks in southcentral Alaska. In addition to determining reference ranges, we found differences in biomarker assay and gene transcription results between parks and sites which indicate variation in both large-scale and local environmental conditions. Our intent is to employ these methods to evaluate Pacific razor clams as a bioindicator of nearshore ecosystem health. Links between the results of the biomarker and gene transcription assays were observed that support the applicability of both assays in ecosystem monitoring. However, we recognize the need for controlled studies to examine the range of responses in physiology and gene transcripts to different stressors.

Seasonal and spatial variations in biomarker baseline levels within Arctic populations of mussels (Mytilus spp.)

Climate change and pollution resulting from human activities in the Arctic require reliable monitoring systems in sentinel species. Mytilus spp. are used as sentinel species all around the world. The use of Mytilus spp. in environmental monitoring requires knowledge about natural variations in pollution biomarkers. Seasonal variations in baseline levels of biomarkers were studied over a year in the mussels from both upper and lower littoral zones in Rakkfjorden, Norway, as they underwent their annual reproductive cycle. Spatial variations of these biomarker baseline levels were measured in five mussel populations within a 60-km radius from Rakkfjorden to investigate universality of the results from the specific population of Rakkfjorden at a regional scale. Seasonal variations in biomarker baseline levels were revealed and seemed to be related to the reproductive state of the mussels and the tidal zone. The mussels appeared to be more sensitive to oxidative stress during gametogenesis in autumn and winter, when having lower lysosome membrane stability and lower baseline levels of antioxidant biomarkers. An increase in baseline levels of these biomarkers was reported during spawning in spring, however, it was not possible to reveal whether these changes were due to spawning, or to a higher metabolic activity in mussels in response to elevated water temperature and food abundance. The differences between the tidal zones were reflected in reduced size of the mussels from the upper littoral zone, their late spawning in the season and increased baseline levels of antioxidant biomarkers during the coldest month, indicating a more challenging environment in the upper littoral zone. The spatial study indicated that the biomarker baseline levels measured in Rakkfjorden were no different from the levels measured in the mussels from five other sites and thus, are representative for mussels on a regional scale.

Bioenergetics-adverse outcome pathway: Linking organismal and suborganismal energetic endpoints to adverse outcomes

Adverse outcome pathways (AOPs) link toxicity across levels of biological organization, and thereby facilitate the development of suborganismal responses predictive of whole-organism toxicity and provide the mechanistic information necessary for science-based extrapolation to population-level effects. Thus far AOPs have characterized various acute and chronic toxicity pathways; however, the potential for AOPs to explicitly characterize indirect, energy-mediated effects from toxicants has yet to be fully explored. Indeed, although exposure to contaminants can alter an organism's energy budget, energetic endpoints are rarely incorporated into ecological risk assessment because there is not an integrative framework for linking energetic effects to organismal endpoints relevant to risk assessment (e.g., survival, reproduction, growth). In the present analysis, we developed a generalized bioenergetics-AOP in an effort to make better use of energetic endpoints in risk assessment, specifically exposure scenarios that generate an energetic burden to organisms. To evaluate empirical support for a bioenergetics-AOP, we analyzed published data for links between energetic endpoints across levels of biological organization. We found correlations between 1) cellular energy allocation and whole-animal growth, and 2) metabolic rate and scope for growth. Moreover, we reviewed literature linking energy availability to nontraditional toxicological endpoints (e.g., locomotor performance), and found evidence that toxicants impair aerobic performance and activity. We conclude by highlighting current knowledge gaps that should be addressed to develop specific bioenergetics-AOPs. Environ Toxicol Chem 2019;38:27-45. © 2018 SETAC.

Highly polluted life history and acute heat stress, a hazardous mix for blue mussels

Intertidal sessile organisms constitute through their life history unintended stress recorders. This study focuses on the impact of pollution on Mytilus edulis ability to cope with an additional stress. For this purpose, two acclimation stages to different temperatures were conducted before an acute stress exposure in mussels collected from a heavily polluted site. Gill proteomes were analyzed by 2DE and regulated proteins identified. Massive mortality was observed for organisms acclimated to colder temperatures. Despite this major difference, both groups shared a common response with a strong representation of proteoforms corresponding to "folding, sorting and degradation" processes. Nevertheless, surviving mussels exhibit a marked increase in protein degradation consistent with the observed decrease of cell defense proteins. Mussels acclimated to warmer temperature response is essentially characterized by an improved heat shock response. These results show the differential ability of mussels to face both pollution and acute heat stress, particularly for low-acclimated organisms.

The physiological effects of oil, dispersant and dispersed oil on the bay mussel, Mytilus trossulus, in Arctic/Subarctic conditions

Increasing oil development around Alaska and other Arctic regions elevates the risk for another oil spill. Dispersants are used to mitigate the impact of an oil spill by accelerating natural degradation processes, but the reduced hydrophobicity of dispersed oil may increase its bioavailability to marine organisms. There is limited research on the effect of dispersed oil on cold water species and ecosystems. Therefore, spiked exposure tests were conducted with bay mussels (Mytilus trossulus) in seawater with non-dispersed oil, Corexit 9500 and oil dispersed with different concentrations of Corexit 9500. After three weeks of exposure, acute and chronic physiological impacts were determined. The majority of physiological responses occurred during the first seven days of exposure, with mussels exhibiting significant cytochrome P450 activity, superoxide dismutase activity and heat shock protein levels. Mussels exposed to non-dispersed oil also experienced immune suppression, reduced transcription and higher levels of mortality. After 21 days, mussels in all treatments exhibited evidence of genetic damage, tissue loss and a continued stress response. Bay mussels are useful as indicators of ecosystem health and recovery, and this study was an important step in understanding how non-dispersed oil, dispersant and dispersed oil affect the physiology of this sentinel species in Arctic/subarctic conditions.

Multi biomarker analysis of pollution effect on resident populations of blue mussels from the Baltic Sea

Anthropogenic pollution including metals, petroleum, toxins, nutrients and many others is a growing problem in the marine environment. These are important factors altering the environment and by that the fate of many local populations of marine organisms. The aim of this study was to assess the impact of selected point pollution sources on resident populations of the blue mussel (Mytilus edulis trossulus) in the Baltic Sea using multiple biomarker approach. The study used a nested sampling scheme in which sites from reference (REF) habitats are geographically paired with selected sites from sewage treatment plants (STP) and harbors (HAR). The results showed that mussels from harbors had a higher frequency of histological abnormalities in the digestive gland compared to mussels from sewage effluent affected areas and reference sites. However these mussels together with mussels from STPs had higher lipid content, body mass index (BMI) and gonado-somatic index (GSI) compared to mussels from reference sites. A marked spatial variability was found with a stronger toxicity of ambient environment affecting resident mussel populations in the Gulf of Gdańsk area, while an opposite pattern was found in Tvärminne area. Yet the blue mussels sampled in the Gulf of Gdańsk were characterized by the highest GSI and BMI values compared to Askö and Tvärminne populations. No differences in analyzed biomarker response related to species identity, measured by a species-specific genetic marker, were found indicative of strong genetic introgression in the Baltic Proper.

High estradiol exposure disrupts the reproductive cycle of the clam Ruditapes decussatus in a sex-specific way

Bivalve species may be susceptible to environmental estrogenic compounds including estradiol (E₂). However, they are able to biotransform the hormone quite readily and inactivate its estrogenic action. To study the long-term effects of elevated free E₂ tissue levels, we transiently exceeded the biotransformation capacity of the clam Ruditapes decussatus by exposing them with high E₂ concentrations (400 ng/L) and subsequently study the consequences on gametogenesis during the following reproductive cycle. Exposure to 400 ngE₂/L led to a significant increase in tissue free E₂ levels, which reached 10-50 ng E₂Eq/gww. No deleterious effect on gonado-somatic index (GSI), condition index (CI), or ability to respond to the stress on stress test could be detected after a month of exposure, suggesting the absence of negative effects on the clam's health. However, a marked increase in gametogenesis could be observed in both sexes during the exposure. Subsequent transplantation of the clams in the field allowed the normal development of the male clams and maturation of the gonads without any detrimental effect observed after 4 months. In contrast, in early July, all female clams formerly exposed to E₂ showed lower health status, and only ovaries with atretic oocytes while all control and indigenous females were normal and mature. These results show a sex-specific effect of high E₂ exposure and suggest either a direct or indirect role for E₂ in R. decussatus' reproduction.

How can we quantify impacts of contaminants in marine ecosystems? The ICON project

An international workshop on marine integrated contaminant monitoring (ICON) was organised to test a framework on integrated environmental assessment and simultaneously assess the status of selected European marine areas. Biota and sediment were sampled in selected estuarine, inshore and offshore locations encompassing marine habitats from Iceland to the Spanish Mediterranean. The outcome of the ICON project is reported in this special issue as method-oriented papers addressing chemical analyses, PAH metabolites, oxidative stress, biotransformation, lysosomal membrane stability, genotoxicity, disease in fish, and sediment assessment, as well as papers assessing specific areas. This paper provides a background and introduction to the ICON project, by reviewing how effects of contaminants on marine organisms can be monitored and by describing strategies that have been employed to monitor and assess such effects. Through the ICON project we have demonstrated the use of an integrating framework and gleaned more knowledge than ever before in any single field campaign about the impacts contaminants may have in European marine areas.

Seasonal and annual variations in physiological and biochemical responses from transplanted marine bioindicator species Mytilus spp. during a long term field exposure experiment

In a pilot field study the long term response of transplanted bioindicator organisms Mytilus spp. was analyzed on the basis of physiological indices and biochemical measurements related to the energy budget. Three different time series with deployment times of eight to twelve months were compared according to seasonality and repeatability of the responses. Test organisms were incubated at a coastal station in the anthropogenically impacted estuary of the river Elbe and at a North Sea station located in vicinity to the Island of Helgoland in the German Bight. The stations differ in their hydrological as well as chemical characteristics. They can be discriminated by statistical factor analysis based on the measured biochemical parameter. Levels of all energy budget biomarker varied between seasons; however, the degree of variation of the specific response was differently expressed. The mussels deployed at Helgoland showed a reproducible high Condition Index in each sampling series and an oscillating Gonadosomatic Index representing the reproduction cycle. The lowest available energy was recorded in mussels at the estuarine sampling station compared to the off-shore station. This may be caused by the energetically costly maintenance of osmotic balance and consequently result in a lower amount of energy available for defense again chemical stress, growth and reproduction.

Biochemical biomarker responses to pollution in selected sentinel organisms across the Eastern Mediterranean and the Black Sea

Pollution effects were assessed by means of biochemical biomarkers (catalase, glutathione S-transferase and acetylcholinesterase activities, and metallothioneins content) in five species at selected coastal sites across the Eastern Mediterranean and the Black Sea. The mussel Mytilus galloprovincialis, a well-established sentinel species, was investigated in the Adriatic Sea, Aegean Sea, and Black Sea. The mussel Brachidontes pharaonis and the striped red mullet Mullus surmuletus were used in the Levantine Sea where M. galloprovincialis is not present. The white seabream Diplodus sargus sargus and the gastropod Rapana venosa were additionally sampled in the Adriatic and the Black Sea, respectively. Mussels showed catalase, glutathione S-transferase, and acetylcholinesterase responses to pollution in most geographical areas while the response of metallothioneins was restricted to a few sites. R. venosa showed marked responses of catalase and metallothioneins whereas both fish species did not generally exhibit variations in biomarker values among sites. The approach based on the reference deviation concept using the "Integrated Biological Responses version 2" index was useful for the interpretation of overall biomarker responses.

In situ evaluation of wastewater discharges and the bioavailability of contaminants to marine biota

Marine sediment quality of wastewater discharges areas was determined by using in situ caged clams Ruditapes philippinarum taking into account the seasonality. Clams were caged in sediment directly affected by wastewater discharges at four sites (P1, P2, P3, P4) at the Bay of Cádiz (SW, Spain), and one reference site (P6). Exposure to contaminated sediments was confirmed by measurement of metals and As, PAH, pharmaceutical products and surfactants (SAS) in bottom sediments. Biological effects were determined by following biomarkers of exposure (activities of 7-ethoxyresorufin O-deethylase - EROD, dibenzylfluorescein dealkylase - DBF, glutathione S-transferase - GST, glutathione peroxidase - GPX, glutathione reductase - GR and acetylcholinesterase - AChE), effects (lysosomal membrane stability - LMS, DNA damage and lipid peroxidation - LPO), energy status (total lipids - TLP and mitochondrial electron transport - MET), and involved in the mode of action of pharmaceutical products (monoamine oxidase activity - MAO, alkali-labile phosphates - ALP levels and cyclooxygenase activity - COX). In winter, urban effluents were detoxified by phase I biotransformation (CYP3A-like activity), phase II (GST), and the activation of antioxidant defence enzymes (GR). Urban effluents lead to the detoxification metabolism (CYP1A-like), oxidative effects (LPO and DNA damage), neurotoxicity (AChE) and neuroendocrine disruption (COX and ALP levels) involved in inflammation (P1 and P2) and changes in reproduction as spawning delay (P3 and P4) in clams exposed in summer. Adverse effects on biota exposed to sediment directly affected by wastewater discharges depend on the chemical contamination level and also on the reproductive cycle according to seasonality.

Effect of nutritive status on Mytilus galloprovincialis pollution biomarkers: Implications for large-scale monitoring programs

Biomarkers have been extensively used in monitoring programs with the aim of assessing the biological effects of pollutants on marine organisms and determining environmental status. Data obtained from these programs are sometimes difficult to interpret due to the large amount of natural variables affecting biological processes, which could act as confounding factors on biomarker responses. The main aim of this work was to identify the effect of one of these variables, the food availability, and consequently, the mussel nutritive status, on biomarker responses. For that purpose, mussels (Mytilus galloprovincialis) were conditioned to three different food rations for 2 months in order to create three mussel nutritive statuses and afterwards, each status was exposed to three nominal concentrations of fluoranthene (FLU) for 3 weeks. A battery of biomarkers was considered in this study to cover a wide range of organism responses, both physiological (scope for growth - SFG) and biochemical (superoxide dismutase - SOD, catalase - CAT, glutathione reductase - GR, glutathione peroxidase - GPx, glutathione-S-transferase - GST and phenoloxidase - PO activities, and lipid membrane peroxidation - LPO). The results obtained, evidenced that most of the studied biomarkers (SFG, SOD, CAT, GPx, and PO) were strongly affected by mussel nutritive status, showing higher values at lower status, whereas the effect of toxicant was not always evident, masked by the nutritive status effect. This paper demonstrates that toxicants are not the only source of variability modulating pollution biomarkers, and confirms nutritive status as a major factor altering biochemical and physiological biomarkers.

Investigation on the proteome response of transplanted blue mussel (Mytilus sp.) during a long term exposure experiment at differently impacted field stations in the German Bight (North Sea)

In a pilot field study the proteome response of Mytilus sp. was analyzed in relation to the concentration of different trace metal contaminants. Over a period of eight month test organisms have been exposed at a near-shore station in the anthropogenic impacted estuary of the river Elbe and at an off-shore station in the vicinity of the Island of Helgoland in the German Bight (North Sea). The stations differ in their hydrological as well as chemical characteristics. The physiological biomarkers, such as condition index which have been continuously monitored during the experiment clearly indicate the effects of the different environmental conditions. Multiple protein abundance changes were detected utilizing the techniques of two dimensional gel electrophoresis (2dGE) and consequently proteins arising as potential candidates for ecotoxicological monitoring have been identified by MALDI-ToF and ToF/ToF mass spectrometry. Different cytoskeletal proteins, enzymes of energy metabolism, stress proteins and one protein relevant for metal detoxification have been pointed out.

Toxicological evaluation of sediment samples spiked with human pharmaceutical products: Energy status and neuroendocrine effects in marine polychaetes Hediste diversicolor

There is a lack of studies about the ecotoxicology of pharmaceutical products on marine environment. To predict possible adverse effects of pharmaceutical products on benthic biota, polychaetes Hediste diversicolor were exposed for 14-days to pharmaceutical-spiked sediments under laboratory conditions. Carbamazepine (CBZ), ibuprofen (IBP) and propranolol (PRO) at concentrations of 500ngg(-1), 50ngg(-1), 5ngg(-1), 0.5ngg(-1) and 0.05ngg(-1), fluoxetine (FX) and 17α-ethynylestradiol (EE2) at concentrations of 100ngg(-1), 10ngg(-1), 1ngg(-1), 0.1ngg(-1) and 0.01ngg(-1), including environmental concentrations (underlined), were spiked in marine sediment samples. After the exposure, cellular energy status (total lipids content - TLP; and mitochondrial electron transport activity - MET), metabolism of monoamines (monoamine oxidase activity - MAO) and inflammation properties (cyclooxygenase activity - COX) were observed in polychaetes. CBZ increased TLP content and MET activity, and decreased MAO activity in polychaetes. IBP did not interfere on the TLP level, but on the MET and MAO activities (environmental concentrations). FX did not cause changes in the energy status. Therefore, environmental concentration diminished MAO activity. EE2 did not affect the energy status, however, MAO activity was significantly lower in polychaetes exposed to environmental concentration. PRO increased TLP level in polychaetes, but not MET activity. MAO activity was significantly lower for polychaetes exposed to environmental concentration. Except FX, all pharmaceuticals showed anti-inflammatory properties confirmed by the decrease of COX activity. Pharmaceutical products affected H. diversicolor physiology and health. As a benthic top predator, adverse effects on sea-worms can potentially culminate in ecosystem perturbations.

Short- and long-term responses and recovery of mussels Mytilus edulis exposed to heavy fuel oil no. 6 and styrene

Biomarkers have the potential to be used to assess the impact of anthropogenic discharges in marine waters. We have used a suite of biomarkers spanning from enzymatic to histopathological alterations and general stress responses to assess the short- and long-term impact on mussels Mytilus edulis of heavy fuel oil no. 6 and styrene. Mussels were exposed for 5 months, with a refilling of the exposure system, to a water soluble fraction of heavy fuel and, then, kept for a month in clean water for recovery. In a second experiment, mussels were exposed to styrene for 19 days and maintained in clean water for up to 4 months. Chemical body tissue levels reflected the weathering processes of these compounds. Acyl-CoA oxidase activity was induced in oil-exposed mussels after refilling, whereas styrene inhibited it after 19 days of exposure and after 2 weeks in clean water. Gamete development and alkali-labile phosphate levels suggest that neither oil nor styrene behaved as endocrine disruptors. Neutral red retention time was lower in treated groups than in controls. Lysosomal membrane stability was significantly reduced in exposed groups and recovered after withdrawal of oil but not after removal of styrene. Neither oil nor styrene exposure affected the condition index except for the reduction seen in mussels exposed to oil for 1 month. Biomarker response index discriminated exposed mussels, which showed higher values, and returned to control levels after recovery. Results obtained from these pilot experiments can help to identify relevant monitoring tools to assess the impact of oil and chemicals in marine spill scenarios.

Gene flow vs. pollution pressure: genetic diversity of Mytilus galloprovincialis in eastern Adriatic

Environmental pollution may modify all the evolutionary processes involved in shaping the genetic patterns of exposed populations. In order to evaluate the pollution impact on the genetic diversity of Mediterranean mussel Mytilus galloprovincialis ten populations inhabiting differently polluted sites along the eastern Adriatic coast, from pristine bays to heavily trafficked harbours, were studied. Pollution pressure was assessed through an integrated study of biological effects and responses across different levels of biological organization. Eight microsatellite markers were analysed to assess genetic diversity of investigated populations. Both the principal component analysis (PCA) of the biomarker data set as well as the biomarker response index (BRI) confirmed substantial pollution pressure at the highly polluted sites, and very low pollution exposure at the three reference sites. Very shallow genetic differentiation was found in respect to maritime distances or pollution status, and this was attributed to a high gene flow among the populations. However, populations inhabiting polluted sites exhibited higher levels of genetic diversity and evolutionary mechanisms underlying this phenomenon are discussed.

The assessment of environmental pollution along the coast of Beibu Gulf, northern South China Sea: an integrated biomarker approach in the clam Meretrix meretrix

The clam Meretrix meretrix was used as a biomonitor to implement an environmental monitoring program along the coast of Beibu Gulf in October 2011. This program not only analyzed biomarkers including acetylcholinesterase, glutathione peroxidase, glutathione S-transferase, catalase and superoxide dismutase activities, total glutathione content and lipid peroxidation level in M. meretrix but also adopted a multi-biomarker approach - integrated biomarker response (IBR) to assess the environmental quality in this ecosystem. In addition, the metal (Hg, As, Cu, Pb, Zn, Cd and Cr) and polychlorinated biphenyls (PCBs) content in the surface sediment at the study area were also measured. The results showed that IBR index was able to distinguish a space trend between sampling sites with different degrees of anthropogenic environmental stress. Integrated contamination degree were displayed in the form of star plots and compared to IBR plots. There was a visual consistency between the pollution level and IBR variation. Based on the results, it was proved that the IBR method coupled with chemical analysis was quite useful for the assessment of environmental pollution in the coastal system.

Comparative study of biochemical and immunological biomarkers in three marine bivalves exposed at a polluted site

A battery of biochemical and immunological biomarkers used for pollution assessment were measured for first time in the clams Venus verrucosa and Callista chione and were compared with those of the mussel Mytilus galloprovincialis, a well-established indicator organism utilized in numerous environmental monitoring programs. Clams and mussel were transplanted at a polluted and a reference site or maintained at the laboratory. Among biochemical biomarkers, acetylcholinesterase did not differ at the polluted site in all species, but there was a significant difference between the mussel and the clams, glutathione S-transferase showed a clear inhibition at the polluted site in all species and a significant difference between the two clams was also indicated, while catalase activities were increased only in V. verrucosa at the polluted site and not in mussel or the other clam. Immunological biomarkers responses were also pronounced at the polluted site. Lysozyme activity was species-dependent whereas respiratory burst activity measured as luminol-dependent chemiluminescence (CL) was site and stimulus dependent, and it was evident in M. galloprovincialis and V. verrucosa and not in C. chione. Further investigation focused on biochemical and immunological biomarkers related with the oxidative mechanisms in clams will strengthen and expand their use as bioindicators for pollution assessment.

The effect of shore location on biomarker expression in wild Mytilus spp. and its comparison with long line cultivated mussels

Biomarkers are a common tool in the assessment of potential effects of contaminants in aquatic organisms. In order to identify the effects of anthropogenic pollution it is essential to identify background levels and to know the range of natural variability in the biomarker response. In this study, we examined various biomarkers of stress (glutathione S-transferase and metallothionein), damage (lipid peroxidation (LPO) and DNA damage (DNA)) and reproduction (vitellin-like proteins) in marine mussels (Mytilus spp.) from four locations along a vertical transect from high to low shore and compared them with cultivated long line mussels. High shore and cultivated mussels showed significantly higher LPO and DNA damage expression than the low shore mussels indicating a level of oxidative stress resulting from mussel location. Significant effects in physiological endpoints were also found. This study highlights the need to consider the diversity of natural environmental stress factors when using biomarkers in environmental assessment.

Main partitioning criteria for the characterization of the health status in the freshwater mussel Anodonta cygnea from spontaneously polluted area in Western Ukraine

The aim of this study was to appreciate the consequences of spontaneous human activity for freshwater mollusks in the generally ecologically sustainable area in Western Ukraine. For this, bivalve mollusk, Anodonta cygnea, at three sites, with mixed agricultural and municipal activities (A), close to a municipal water inlet (F) and the cooling pond of a nuclear power plant (N), were studied in spring, summer, and autumn. The set of parameters included the characteristics of oxidative stress (activity of catalase (CAT), levels of protein carbonyls (PC)), levels of reduced and oxidized glutathione (GSH, GSSG, respectively), activities of lactate dehydrogenase (LD), cholinesterase (ChE), ethoxyresorufin-O-deethylase (EROD), glutathione S-transferase (GST) in the digestive gland, and concentrations of vitellogenin-like proteins (Vtg-LP) in gonads and also morphological indices. Although the discriminant functional analysis confirmed the general seasonal regularities for studied groups, it allowed to discriminate between sites (P < 0.05). At site A, oxidative stress; high levels of LD, EROD, and GST; and low levels of ChE and condition factor were reflected. This demonstrated the sensitivity of mussels to constant effect of mixed pollution. At site N, oxidative injury was shown that might be explained by the constantly high temperature. At site F, abrupt elevations of Vtg-LP and EROD levels in autumn were probably related to an emergency situation on the nearby dump. So, both chronic and temporal environmental effects were reflected by a set of markers in mollusk. The classification and regression tree (CART) algorithm selected GSH and PC in the digestive gland and Vtg-LP as partitioning criteria for the characterization of mussel health status. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012.

Active biomonitoring in Greek coastal waters: application of the integrated biomarker response index in relation to contaminant levels in caged mussels

An integrated approach using biomarkers and contaminant levels in mussels Mytilus galloprovincialis L. was employed to assess chemical contamination in Greek coastal waters within the framework of the MYTIMED program. Biomarkers (metallothioneins, glutathione S-transferase, catalase, acetylcholinesterase and RNA:DNA ratio) have been previously described in mussels caged at 14 sites in coastal areas influenced by different types of anthropogenic activities. This study applied a biomarker index, the Integrated Biomarker Response (IBR) to summarize biomarker responses and relate stress levels to concentrations of organochlorine compounds (PCBs, DDTs), polycyclic aromatic hydrocarbons (PAHs), and metals (Cu, Ni, Fe, Zn) measured in the mussel tissues. The IBR index indicated environmental stress at sites near cities and industries and was overall related to organic contaminants, but also elevated metal concentrations at certain sites. Slightly increased IBR values at few sites away from known pollution sources were not accompanied with increased contaminant levels suggesting stress possibly caused by natural factors. Results confirmed the usefulness of integration of biological effects measurements and chemical analysis for the assessment of chemical contamination in coastal waters.

Heavy metal concentrations and biomarkers of oxidative stress in native mussels (Mytilus edulis chilensis) from Beagle Channel coast (Tierra del Fuego, Argentina)

The aim of this study was to evaluate the usefulness of oxidative stress biomarkers of pollution in native mussels Mytilus edulis chilensis from the Beagle Channel. Spatial and seasonal variations of catalase, glutathione-S-transferase and lipid peroxidation in gills and digestive gland were analyzed in relation to environmental parameters, heavy metals in sediment and in tissue. Four sites with anthropogenic impact and a control site were selected and monitored during the four seasons of 2007. We found significant differences among sites in concentrations of dissolved nutrients and heavy metals in sediments, with the highest values recorded at sites with anthropogenic pressure. Different patterns were observed between concentrations of metals in tissues and in sediments suggesting differences in bioavailability. There were also significant differences in biomarker responses among sites, despite the strong seasonal variability. Our results showed relatively moderate levels of pollution in the study area as a result of urban influences.

Use of biomarkers in resident organisms as a tool for environmental monitoring in a cold coastal system, Tierra del Fuego Island

Antioxidant status of Nacella (P) magellanica and Mytilus edulis related with heavy metal in sediment and tissues were analysed in five stations close to Ushuaia city in winter and spring. The principal component analysis produced a two-dimensional pattern of the degree of similarity between sites. The Industrial-Urban Contamination Index (IUCI) showed that the Industrial Zone (IZ) and Oil Marine Station (OMS) represent areas with anthropic inputs. Heavy metals have differential association with biomarkers depending on the species. In limpets, digestive gland presented major activities of enzyme defence in winter and gonads have shown higher values of Catalase (CAT) during spring while lipid peroxidation (LPO) presented higher values in IZ. For mussels CAT and LPO increased in spring time. For superoxide dismutase (SOD) peaks have been detected in IZ and NW stations for winter. Differences in biomarker responses due to seasons did not influence the grouping of the sites into references and contaminated groups.

Assessment of the genotoxic potential of contaminated estuarine sediments in fish peripheral blood: laboratory versus in situ studies

Juvenile Senegalese soles (Solea senegalensis) were exposed to estuarine sediments through 28-day laboratory and in situ (field) bioassays. The sediments, collected from three distinct sites (a reference plus two contaminated) of the Sado Estuary (W Portugal) were characterized for total organic matter, redox potential, fine fraction and for the levels of metals, polycyclic aromatic hydrocarbons (PAHs) and organochlorines, namely polychlorinated biphenyls (PCBs) and dichloro diphenyl tricholoethane plus its main metabolites (DDTs). Genotoxicity was determined in whole peripheral blood by the single-cell gel electrophoresis (SCGE or "comet") assay and by scoring erythrocytic nuclear abnormalities (ENA). Analysis was complemented with the determination of lipid peroxidation in blood plasma by the thiobarbituric acid reactive substances (TBARS) protocol and cell type sorting. The results showed that exposure to contaminated sediments induced DNA fragmentation and clastogenesis. Still, laboratory exposure to the most contaminated sediment revealed a possible antagonistic effect between metallic and organic contaminants that might have been enhanced by increased bioavailability. The laboratory assay caused a more pronounced increase in ENA whereas a very significant increase in DNA fragmentation was observed in field-tested fish exposed to the reference sediment, which is likely linked to increased lipid peroxidation that probably occurred due to impaired access to food. Influence of natural pathogens was ruled out by unaltered leukocyte counts. The statistical integration of data correlated lipid peroxidation with biological variables such as fish length and weight, whereas the genotoxicity biomarkers were more correlated to sediment contamination. It was demonstrated that laboratory and field bioassays for the risk assessment of sediment contamination may yield different genotoxicity profiles although both provided results that are in overall accordance with sediment contamination levels. While field assays may provide more ecologically relevant data, the multiple environmental variables may produce sufficient background noise to mask the true effects of contamination.

Comparison of two reference systems for biomarker data analysis in a freshwater biomonitoring context

The usefulness of fish biomarkers for freshwater biomonitoring is now well recognized, but they still pose several questions to ecotoxicology researchers. The present study, designed to assess the effects of a small city located in an agricultural river basin watershed on sticklebacks living in an adjacent river, underlines the importance of reference selection. Two reference systems were used to analyse responses of a set of biomarkers, including biotransformation enzymes, oxidative stress parameters, neurotoxicity and endocrine disruption end-points, measured in wild sticklebacks electrofished in a contaminated stream. The results showed that the investigated urban pressure disturbed CYP3A activity but also induced hepatic lipoperoxidation and circulating vitellogenine but this result is strongly influenced by the selected reference system. This work therefore demonstrates the need for further research to identify a robust reference system for stickleback biomarker analysis.