Impact of chemical exposure on the fish Pomatoschistus microps Krøyer (1838) in estuaries of the Portuguese Northwest coast

Multibiomarker responses to polycyclic aromatic hydrocarbons and microplastics in thumbprint emperor Lethrinus harak from a South Pacific locally managed marine area

To determine the baseline threat of microplastics and polycyclic aromatic hydrocarbons (PAHs) in an important seafood fish from Vueti Navakavu locally managed marine area, a multibiomarker risk assessment was conducted on the thumbprint emperor fish Lethrinus harak. Condition factor, a measure of relative general health condition of fish, was significantly lower in samples from the wet season compared to the dry season but no significant differences were observed for hepatosomatic index, a measure of relative stored energy/nutrition, between seasonal groups. PAHs levels of four metabolites in emperor fish from Fiji waters are reported here for the first time; seasonal groups showed no significant differences, but all samples presented levels of biliary PAHs. Each specimen also contained at least one microplastic in its gastrointestinal system; fibres were the predominant form-type and ingestion levels showed that more than 80% of fragment sizes were below 1.0 mm. Biochemical responses were observed for ethoxyresorufin-O-deethylase and glutathione S-transferase biotransformation activity, oxidative stress (glutathione peroxidase and glutathione reductase activity; lipid peroxidation) and genotoxicity (micronuclei assay). Though there were no statistically significant differences found, there were biological significances that were important to note; relatively low levels of pollutant exposure and low levels of biochemical responses showed enzymes response in thumbprint emperor were as expected to their roles in the body. In this multibiomarker approach, the observation of pollutants presence and histopathological injuries are considered biologically relevant from a toxicological perspective and serve as a baseline for future pollution studies in seafood fishes in Fiji, with site differences and the inclusion of fish species comparison. We recommend adopting a suite of biomarkers in future regional biomonitoring studies to develop holistic baseline information for other marine settings in Fiji and other Pacific Island countries.

Biochemical aspects of susceptibility to stressors in two small cyprinids Squalius laietanus and Barbus meridionalis from the NW Mediterranean

Specimens of two endemic cyprinids, Squalius laietanus (Catalan chub) and Barbus meridionalis (Mediterranean barbel), were sampled from a reference site in a small stream of the Ripoll River (NW Mediterranean) outside of their reproductive season. Biomarkers involved in xenobiotic-mediated responses were individually contrasted in fish of both species and 17 perfluoroalkyl substances (PFASs) analysed in muscle to reveal bioaccumulation trends. The parameters were in muscle: cholinesterases, metabolic lactate dehydrogenase (LDH) and citrate synthase (CS); and in liver: cytochrome P450 dependent activities (EROD and BFCOD), carboxylesterase (CE), glutathione S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPX) and catalase (CAT). All markers are considered adaptive defence mechanism to face stress. Sensitivity to a model pesticide: dichlorvos was also contrasted in vitro in muscular acetylcholinesterase (AChE) and hepatic CE to reveal species sensitivity to neurotoxic chemicals. Enzymatic activities related to protective mechanisms such as butyrylcholinesterase (BuChE), CE and CAT were higher in chub whereas the antioxidant defences GR and GPX were higher in barbel. Aerobic CS was also higher in barbel while anaerobic LDH was so in chub. EROD activity did not differ between the two species but BFCOD activity was higher in barbel. Levels of PFAS were higher in barbel likely due to its benthic habitat. The in vitro tests revealed higher sensitivity to dichlorvos of muscular AChE in chub (lower IC50) which was probably compensated by a higher catalytic efficiency of CE. All these former biochemical particularities are discussed in terms of fish ecological performance in front of anthropogenic stressors.

Acetylcholinesterase activity in fish species exposed to crude oil hydrocarbons: A review and new perspectives

Crude oil and its derivatives are primary energy resources for humans, and processes involving these materials could affect aquatic environments. Acetyl cholinesterase (AChE) activity is a suitable biomarker for exposure to organophosphate pesticides. Under controlled conditions, fish exposed to polycyclic aromatic hydrocarbons (PAHs), such as benzo[a]pyrene, pyrene and anthracene, showed inhibition of this biomarker; however, PAHs with a low molecular weight did not induce changes or cause stimulation of AChE activity. Diverse responses of fish exposed to soluble fractions of crude oil, fuels or gasoline were documented. Most studies in which AChE activity was considered for environmental monitoring have been performed to evaluate the presence of pesticides, and the effects of petroleum hydrocarbons are unclear. The objective of this review was to provide the recent status of research on this topic and suggest proposals for future investigations. To establish the suitability of this biomarker in fish species exposed to these pollutants and to determine their neurotoxic effects, researchers must determinate the mechanism involved in the AChE inhibition by petroleum hydrocarbons, unify criteria concerning the experimental in vitro and in vivo designs and apply multivariate statistical and correlation analyses between these pollutants with AChE activity in field studies.

First baseline for bioenergetic biomarkers in Cnesterodon decemmaculatus as test organism in ecotoxicological studies

Cnesterodon decemmaculatus is a Neotropical teleost fish frequently used in ecotoxicological evaluations, whose biology has been thoroughly studied. Although there is considerable information on its response to different toxicants, no range of reference values has been so far established for the different biological parameters proposed as biomarkers of effect or exposure. Moreover, no study has yet examined the possible influence of the metabolic status of the exposed animals on their response to toxic stress. Therefore, the aim of this work was to provide a first baseline for a set of bioenergetic biomarkers in C. decemmaculatus adults exposed to a control medium under previously standardized conditions, and to assess their possible intrinsic seasonal variability. The responses of the biomarkers obtained from the controls were contrasted with those from the reference toxicant (Cadmio-Cd) and receiving waters (surface waters of the Reconquista River RR, Buenos Aires Province, Argentina). We conducted four 12-day assays (one in each season) of exposure to control media, (reconstituted moderate hard water, MHW) and two assays of exposure to Cd in MHW and surface river water (RR) in both summer and autumn. The variables recorded were: Food intake (In), fecal production (F), specific assimilation (A) and cumulative mortality, oxygen extraction efficiency (OEE), specific metabolic rate (SMR), ammonia excretion (N), ammonia quotient (AQ) and scope for growth (SFG). The seasonal variation shown by some physiological parameters, points to the need for establishing a baseline obtained from standardized media, preferably on a seasonal basis. Moreover, SFG and A appeared as the most sensitive biomarkers, emphasizing the importance to consider the metabolic status of the test organisms for the appropriate interpretation of results from ecotoxicological studies performed under controlled experimental conditions. The obtained results provide useful information on C. decemmaculatus as model species in ecotoxicological bioassays involving biomarkers of early effect.

Neurotoxicity, Behavior, and Lethal Effects of Cadmium, Microplastics, and Their Mixtures on Pomatoschistus microps Juveniles from Two Wild Populations Exposed under Laboratory Conditions-Implications to Environmental and Human Risk Assessment

Microplastics (MPs) were found to modulate the toxicity of other pollutants but the knowledge on the topic is still limited. The goals of this study were to investigate the short-term toxicity of cadmium (Cd) to wild Pomatochistus microps juveniles, the potential modulation of acute Cd toxicity by 1-5 µm polyethylene MPs in this species, and possible differences of sensitivity to Cd and MPs-Cd mixtures between juveniles from two distinct wild populations. Juveniles were collected in the estuaries of Minho (M-est) and Lima (L-est) Rivers (NW Portugal). One 96 h bioassay with M-est juveniles and another one with L-est juveniles were carried out in laboratory conditions. Each bioassay had 12 treatments: control, 5 Cd concentrations, 1 MPs concentration, and 5 MPs-Cd mixtures. No significant differences in Cd-induced mortality between juveniles from distinct estuaries or between juveniles exposed to Cd alone and those exposed to MPs-Cd mixtures were found. The total 96h LC10 and LC50 of Cd alone were 2 mg/L (95% CI: 0-4 mg/L) and 8 mg/L (95% CI: 2-17 mg/L), respectively. Cd alone significantly decreased the post-exposure predatory performance (PEPP) of M-est (≥6 mg/L) and L-est juveniles (≥3 mg/L), and acetylcholinesterase (AChE) activity of M-est juveniles (13 mg/L). MPs alone (0.14 mg/L) significantly reduced the PEPP and AChE activity of L-est juveniles but not of M-est juveniles. MPs-Cd mixtures (3-13 mg/L of Cd + 0.14 mg/L of MPs) significantly inhibited the PEPP of juveniles from both estuaries and AChE of L-est estuary juveniles but not of M-est juveniles. Evidences of toxicological interactions, namely antagonism, between MPs and Cd were found. Overall, the results indicate that MPs modulated the sub-lethal toxic effects of Cd in wild P. microps juveniles, especially neurotoxicity. Moreover, the environmental conditions of the natural habitats to which juveniles were exposed during pre-developmental phases influence the sub-lethal toxicity of Cd, MPs, and their mixtures. The implications to environmental and human risk assessment are discussed and further research is needed.

Effects of Multi-Component Mixtures from Sewage Treatment Plant Effluent on Common Carp (Cyprinus carpio) under Fully Realistic Condition

This study characterized changes in biomarker responses in common carp (Cyprinus carpio) upon exposure to effluent water discharged from a sewage treatment plant (STP) under real conditions. Fish were exposed to contamination in Cezarka pond, which receives all of its water input from the STP in the town of Vodnany, Czech Republic. Five sampling events were performed at day 0, 30, 90, 180, and 360 starting in April 2015. In total, 62 pharmaceutical and personal care products (PPCPs) were detected in the polar organic chemical integrative sampler. Compared to a control pond, the total concentration of PPCPs was 45, 16, 7, and 7 times higher in Cezarka pond at day 30, 90, 180, and 360, respectively. The result of oxidative stress and antioxidant enzyme biomarkers indicated alterations in the liver and intestine tissues of fish from Cezarka pond at day 30 and 360, respectively. High plasma vitellogenin levels were observed in both exposed females (180 and 360 days) and males (360 days) compared with their respective controls. However, only exposed female fish had higher vitellogenin mRNA expression than the control fish in these periods. Exposed female fish showed irregular structure of the ovary with scattered oocytes, which further developed to a vitellogenic stage at day 360. Low white blood cell levels were indicated in all exposed fish. Despite numerous alterations in exposed fish, favorable ecological conditions including high availability of food resulted in a better overall condition of the exposed fish after 1 year of exposure compared to the controls.

Toxicity of erythromycin to Oncorhynchus mykiss at different biochemical levels: detoxification metabolism, energetic balance, and neurological impairment

During the last decades, the presence of antibiotics in different aquatic compartments has raised increasing interest and concern, since these compounds are usually persistent and bioactive pseudo pollutants. Erythromycin (ERY) is a macrolide antibiotic, prescribed for human and veterinary medicines but also used in aquaculture and livestock production. Taking into account the recorded environmental levels of ERY, its toxicity to non-target organisms has become a still poorly studied issue, particularly in fish. In this sense, this study investigated the acute and chronic effects of realistic levels of ERY on Oncorhynchus mykiss (rainbow trout), namely, through the quantification of the activity of enzymes involved in different biochemical pathways, such as detoxification (phase I-7-ethoxyresorufin O-deethylase (EROD); phase II-glutathione S-transferases (GSTs), uridine-diphosphate-glucuronosyltransferases (UGTs)), neurotransmission (acetylcholinesterase (AChE)), and energy production (lactate dehydrogenase (LDH)). Both types of exposure caused significant increases in EROD activity in liver of O. mykiss; an increase in GST activity in gills after chronic exposure was also observed. UGT branchial activity was significantly depressed, following the long-term exposure. Thus, EROD, GST, and UGT enzymatic forms seem to be involved in the biotransformation of ERY. In terms of neurotransmission and preferential pathway of energy homeostasis, the exposed organisms appear not to have been affected, as there were no significant alterations in terms of AChE and LDH activities, respectively. The here-obtained data suggest that the observed alterations in terms of detoxification enzymes may have prevented the establishment of a set of toxic responses, namely, neurotoxic and metabolic disorders.

Oxytetracycline effects in specific biochemical pathways of detoxification, neurotransmission and energy production in Oncorhynchus mykiss

Oxytetracycline (OTC) is a tetracycline antibiotic, widely used in human and veterinary medicines, including in aquaculture. Given this use, OTC has been detected in different aquatic environments. Some recent works have demonstrated unintentional biological activity of OTC in non-target aquatic organisms. This study investigated the acute and chronic effects of OTC on the physiology of the fish species Oncorhynchus mykiss (rainbow trout), namely through the quantification of the activity of enzymes involved in different biochemical pathways, such as detoxification (phase II - glutathione S-transferases - GSTs, uridine-diphosphate-glucuronosyltransferases - UGTs), neurotransmission (acetylcholinesterase - AChE) and energy production (lactate dehydrogenase - LDH). The here-obtained data demonstrated the induction of GSTs activity in gills, and inhibition of AChE activity in eyes tissue, in chronically exposed organisms, as well as alterations in LDH activity following both exposures. Considering this set of results, we can infer that OTC exposure may have induced the glutathione pathway of detoxification in gills with the involvement of GSTs, or indirectly due to the metabolites that may have been produced. In turn, these metabolites may have interfered with the mechanism of neurotransmission, also causing physiological and biochemical disturbances in rainbow trout after OTC exposure, namely disturbances in energetic metabolism. In addition, it is important to stress that such occurrences took place at low, environmentally realistic levels of OTC, suggesting that organisms exposed in the wild may be putative targets of toxic effects by commonly used drugs such as antibiotics.

Malathion induced oxidative stress leads to histopathological and biochemical toxicity in the liver of rohu (Labeo rohita, Hamilton) at acute concentration

Organophosphorus pesticides form a diverse group of chemicals, having a wide range of physicochemical properties with crucial toxicological actions and endpoints. These are extensively used to control pests of different food (fruits, vegetables, tea, etc.) and non-food (tobacco, cotton, etc.) crops. Malathion is an important widely used organophosphorus pesticide but its hepatotoxic effects on fish are not well studied. Therefore, the current study was designed to investigate the hepatotoxic effects of Malathion on rohu (Labeo rohita) fish in a semi-static system using different parameters. The LC₅₀ of Malathion was found to be 5 µg/L for rohu for 96 h through Probit analysis and was used for further toxicity testing. To find the hepatotoxic effects of Malathion, changes in different biochemical indices including protein contents, Lipid Peroxidation (LPO), activities of four protein metabolic enzymes [Aspartate Aminotransferase (AAT), Lactate Dehydrogenase (LDH), Alanine Aminotransferase (AlAT), and Glutamate Dehydrogenase (GDH)], seven antioxidant enzymes [Catalase (CAT), Superoxide Dismutase (SOD), Peroxidase (POD), Glutathione (GSH), Glutathione Reductase (GR), Glutathione-s-transferase (GST), and Glutathione Peroxidase (GSH-Px)], DNA damage [in term of comet tail length, tail moment, DNA percentage in tail, and olive tail moment], reactive oxygen species (ROS), and Histopathological alterations were assayed. Malathion exposure led to a time-reliant significant (P < 0.05) decrease in protein contents and a significant (P < 0.05) increase in ROS, LPO, enzymatic activities, and DNA damage. The histopathological examination of the liver showed different changes including hepatic necrosis, fatty infiltration, hemorrhage vacuolation, glycogen vacuolation, congestion, and cellular swelling. The current study clearly revealed Malathion as a potent hepatotoxic pesticide; therefore the injudicious, indiscriminate and extensive use of Malathion should be prohibited or at least reduced and strictly monitored.

Liver histopathology and biochemical biomarkers in Gobius niger and Zosterisessor ophiocephalus from polluted and non-polluted Tunisian lagoons (Southern Mediterranean Sea)

The aim of this study was to appraise the response of a multi-marker approach in fish species, Gobius niger and Zosterisessor ophiocephalus, in a polluted lagoon (Bizerte lagoon: MB and ML sites) and in a reference site (Ghar-El-Melh lagoon entrance) by the analysis of physiological indexes, liver histopathology and some biochemical biomarkers. The results showed liver hypertrophy in fish collected from Bizerte lagoon as well as many non-specific lesions, unlike the reference site. All Bizerte lagoon sites had the same prevalence of histopathological lesions, but the mean intensity (MI) of parasites seemed to be more sensible as an indicator of pollution levels. Indeed, parasite MI was more important in MB site that has a higher pollution level. Also, biochemical biomarkers showed an induction in Bizerte lagoon sites with some differences within sites and species. The impact of the continuous release of pollution on the biomarker's response is discussed.

Biochemical responses of Solea senegalensis after continuous flow exposure to urban effluents

Urban effluent potential toxicity was assessed by a battery of biomarkers aimed at determining sub-lethal effects after continuous exposure on the marine organism Solea senegalensis. Specimens were exposed to five effluent concentrations (1/2, 1/4, 1/8, 1/16, 1/32) during 7-days, simulating the dispersion plume at the discharge point. Three different groups of biomarkers were selected in the present study: biomarkers of exposure (Phase I: EROD and DBF; Phase II: GST), biomarkers with antioxidant responses (GR and GPX) and biomarkers of effects (DNA damage and LPO). Additionally, a biological depuration treatment (photobiotreatment (PhtBio)) was tested in order to reduce the adverse effects on aquatic organisms. Effluent exposure caused sub-lethal responses in juvenile fish suggesting oxidative stress. After PhtBio application, concentrations of the major part of measured contaminants were reduced, as well as their bioavailability and adverse effects.

Effects of 4-MBC and triclosan in embryos of the frog Pelophylax perezi

The widespread and increasing use of personal care products (PCPs) have led to environmental contamination by substances included in these products. These substances have been detected in aquatic compartments and shown to cause adverse effects on non-target aquatic organisms. In this work toxicity of the antimicrobial triclosan (TCS) and of the UV-filter 3-(4-methylbenzylidene) camphor (4-MBC) was assessed in the embryos of Perez' frog Pelophylax perezi. Lethal and sub-lethal parameters were evaluated in embryos in Gosner stage 8-9 exposed to 0.00013-1.3 mg/l of 4-MBC and 0.25-2.50 mg/l of TCS during 144 h. Survival, malformations, length and hatching were evaluated as apical endpoints. Biomarkers of neurotransmission, oxidative stress, energy metabolism and estrogenicity were determined at the biochemical level through the activities of cholinesterase (ChE), catalase (CAT), glutathione S-transferase (GST), lactate dehydrogenase (LDH) and levels of lipid peroxidation (LPO) and vitellogenin (Vtg). Embryo exposure to 4-MBC led to few developmental malformations (up to 3%) and a GST induction at 0.013 mg/l. Triclosan exposure reduced survival, delayed hatching (at 72 h) and development and induced malformations. In addiction ChE was inhibited in the highest concentrations tested and GST and LDH were induced at 0.79 mg/l, the LOEC registered for TCS in Perez' frogs. Overall, our study showed that TCS might exert adverse effects on P. perezi early life stages, but only at four orders of magnitude above the concentrations found in environment. Furthermore, our results highlight the need to assess PCPs toxicity at different levels of biological organization.

Temperature rise and microplastics interact with the toxicity of the antibiotic cefalexin to juveniles of the common goby (Pomatoschistus microps): Post-exposure predatory behaviour, acetylcholinesterase activity and lipid peroxidation

The goal of this study was to investigate the toxicity of cefalexin to Pomatoschistus microps juveniles in relation to the presence of microplastics in the water and temperature rise. After acclimatization, groups of wild juveniles were exposed for 96h to artificial salt water (control), microplastics alone (0.184mg/l), cefalexin alone (1.3-10mg/l) and in mixture with microplastics (cefalexin: 1.3-10mg/l; microplastics: 0.184mg/l) at 20 and 25°C. Effect criteria were mortality, post-exposure predatory performance (PEPP), acetylcholinesterase activity (AChE) and lipid peroxidation levels (LPO). At 20°C, concentrations of cefalexin alone≥5mg/l significantly reduced PEPP (up to 56%; 96h-EC₅₀=8.4mg/l), indicating toxicity of the antibiotic to juveniles after short-term exposure to water concentrations in the low ppm range. At 20°C, fish exposed to microplastics alone did not have significant differences in any of the parameters tested relative to the control group but tended to have an inhibition of the PEPP (23%) and AChE (21%); at 25°C, microplastics alone caused mortality (33%) and PEPP inhibition (28%). Thus, microplastics are toxic to P. microps juveniles. At 20°C, under simultaneous exposure to cefalexin and microplastics, the PEPP was significantly reduced (at cefalexin concentrations≥1.25mg/l). Moreover, at 25°C, the toxicity curves of cefalexin (PEPP based), alone and in mixture with microplastics, were significantly different (p<0.05; 96h-EC₅₀ of 3.8 and 5.2mg/l, respectively), and the integrated data analysis indicated significant interactions between the two substances for all biomarkers. Thus, the presence of microplastics in the water influenced the toxicity of cefalexin. The rise of water temperature (from 20°C to 25°C), increased the microplastics-induced mortality (from 8 to 33%), and the inhibitory effects of cefalexin on the PEPP (up to 70%). Significant differences (p<0.05) between the toxicity curves of cefalexin alone at distinct temperatures were found, with a lower 96h-EC₅₀ at 25°C (3.8mg/l) than at 20°C (8.4mg/l). Moreover, at 25°C, increases of AChE activity (14%) and LPO (72%) in fish exposed to the mixture treatment containing the highest cefalexin concentration were found, and the integrated analysis of data indicated significant interactions between cefalexin and temperature for PEPP, and among all stressors for LPO. Thus, the temperature rise increased the toxicity of microplastics and of cefalexin, alone and in mixture with microplastics, to P. microps juveniles. These findings raise concern on the long-term exposure of wild populations to complex mixtures of pollutants, likely decreasing their fitness, and highlight the need of more research on the combined effects of widely used pharmaceuticals, microplastics and temperature increase on wild species to improve environmental and human risk assessments of chemicals and their safe use under a global warming scenario.

Effects of multi-stressors on juveniles of the marine fish Pomatoschistus microps: Gold nanoparticles, microplastics and temperature

Knowledge on multi-stressors effects required for environmental and human risk assessments is still limited. This study investigated the combined effects of gold nanoparticles (Au-NP), microplastics (MP) and temperature increase on Pomatoschistus microps, an important prey for several higher level predators, including some species edible to humans. Four null hypotheses were tested: H01: P. microps juveniles do not take up Au-NP through the water; H02: Au-NP (ppb range) are not toxic to juveniles; H03: the presence of MP do not influence the effects of Au-NP on juveniles; H04: temperature increase (20-25°C) does not change the effects of the tested chemicals on juveniles. Wild juveniles were acclimated to laboratory conditions. Then, they were exposed to Au-NP (≈5nm diameter) and MP (polyethylene spheres, 1-5μm diameter), alone and in mixture, at 20°C and 25°C, in semi-static conditions. After 96h of exposure to Au-NP, fish had gold in their body (0.129-0.546μg/g w.w.) leading to H01 refusal. Exposure to Au-NP alone caused a predatory performance decrease (≈-39%, p<0.05) leading to H02 refusal. MP did not change the Au-NP toxicity leading to H03 acceptance. Temperature rise significantly increased the concentration of gold in fish exposed to Au-NP (≈2.3 fold), and interacted with chemical effects (e.g. glutathione S-transferases activity) leading to H04 refusal. Thus, the results of this study highlight the importance of further investigating the effects of multi-stressors on marine fish, particularly the effects of temperature on the uptake, biotransformation, elimination and effects of nanoparticles and microplastics, either alone or in mixture. This knowledge is most important to improve the basis for environmental and human risk assessments of these environmental contaminants of high concern.

Yes, caffeine, ibuprofen, carbamazepine, novobiocin and tamoxifen have an effect on Corbicula fluminea (Müller, 1774)

Reports indicating the presence of pharmaceutical in fresh water environment in the ngL(-1) to µgL(-1) range are occurring with increasing frequency. It is also a fact that pharmaceuticals may produce adverse effects on aquatic organisms. Nevertheless, there is still a lack of knowledge regarding how these emergent contaminants may affect aquatic biota. The goal of this research was to evaluate the sublethal responses in Corbicula fluminea such as, general stress (lysosomal membrane stability [LMS]), biomarkers of phase I and II (etoxyresorufin O-deethylase [EROD], dibenzylfluorescein dealkylase [DBF], gluthathione-S-transferase [GST]), oxidative stress (gluthathione reductase [GR], gluthathione peroxidase [GPX], lipid peroxidation [LPO]), and biomarkers of effect (DNA damage) after 21 days of exposure to caffeine, ibuprofen, carbamazepine, novobiocin and tamoxifen at 0.1, 1, 5, 10, 15, 50µgL(-1). Environmental concentrations tested in this study caused general stress and produced changes on biomarkers tested. LMS, responses from phase I and II enzymatic activity, oxidative stress, and biomarker of effect represent important ecotoxicological information, and will provide a useful reference for the assessment of selected drugs and the effects which these compounds may have on aquatic invertebrates, using C. fluminea as a bioindicator species.

Hepatotoxicity of herbicide Sencor in goldfish may result from induction of mild oxidative stress

The effects of 96 h exposure to 7.14, 35.7, or 71.4 mg L(-1) of Sencor were studied on liver and plasma parameters in goldfish, Carassius auratus L. Goldfish exposure to 71.4 mg L(-1) of Sencor for 96 h resulted in a decrease in glucose concentrations in plasma and liver by 55%, but did not affect liver glycogen levels. An increase in the activity of aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase (by 24-27%, 32-72%, and 87-102%, respectively) occurred in plasma of Sencor exposed goldfish, whereas in liver activities of these enzymes decreased (by 15-17%, 19%, and 20%, respectively). Lactate concentration in plasma increased by 22-36% in all treated fish groups, whereas in liver it increased by 64% only after exposure to 35.7 mg L(-1) of Sencor. Herbicide exposure enhanced lipid peroxide levels by 49-75% and decreased activities of catalase by 46%, glutathione reductase by 25-48% and glutathione peroxidase by 21-26% suggesting development of oxidative stress in liver. The treatment induced various histological changes in goldfish liver, such as dilated sinusoids, hypertrophy and dystrophy of hepatic cells and detachment of endothelial cytoplasm with diffuse hemorrhage. The data collectively let us propose that mild oxidative stress might be responsible for the hepatotoxicity of Sencor.

Does the presence of microplastics influence the acute toxicity of chromium(VI) to early juveniles of the common goby (Pomatoschistus microps)? A study with juveniles from two wild estuarine populations

Toxicological interactions between microplastics (MP) and other environmental contaminants are of grave concern. Here, the potential influence of MP in the short-term toxicity of chromium to early juveniles of Pomatoschistus microps was investigated. Three null hypotheses were tested: (1) exposure to Cr(VI) concentrations in the low ppm range does not induce toxic effects on juveniles; (2) the presence of microplastics in the water does not influence the acute toxicity of Cr(VI) to juveniles; (3) the environmental conditions of the natural habitat where fish developed do not influence their sensitivity to Cr(VI)-induced acute stress. Fish were collected in the estuaries of Minho (M-est) and Lima (L-est) Rivers (NW Iberian Peninsula) that have several abiotic differences, including in the water and sediment concentrations of various environmental contaminants. After acclimatization to laboratory conditions, two 96h acute bioassays were carried out with juveniles from both estuaries to: (i) investigate the effects of Cr(VI) alone; (ii) investigate the effects of Cr(VI) in the presence of MP (polyethylene spheres 1-5μm ∅). Cr(VI) alone induced mortality (96h-LC50s: 14.4-30.5mg/l) and significantly decreased fish predatory performance (≤74%). Thus, in the range of concentrations tested (5.6-28.4mg/l) Cr(VI) was found to be toxic to P. microps early juveniles, therefore, we rejected hypothesis 1. Under simultaneous exposure to Cr(VI) and MP, a significant decrease of the predatory performance (≤67%) and a significant inhibition of AChE activity (≤31%) were found. AChE inhibition was not observed in the test with Cr(VI) alone and MP alone caused an AChE inhibition ≤21%. Mixture treatments containing Cr(VI) concentration ≥3.9mg/l significantly increased LPO levels in L-est fish, an effect that was not observed under Cr(VI) or MP single exposures. Thus, toxicological interactions between Cr(VI) and MP occurred, therefore, we rejected hypothesis 2. In the presence of MP, the negative effect caused by high concentrations of Cr(VI) on the predatory performance was significantly reduced in L-est fish but not in M-est fish, and Cr(VI) concentrations higher than 3.9mg/l caused oxidative damage in L-est fish but not in M-est fish. The acclimatization and test conditions were similar for fish from the two estuaries and these ecosystems have environmental differences. Thus, long-term exposure to distinct environmental conditions in the natural habitat during previous developmental phases influenced the sensitivity and responses of juveniles to Cr(VI), therefore, we rejected hypothesis 3. Overall, the results of this study indicate toxicological interactions between MP and Cr(VI) highlighting the importance of further investigating the combined effects of MP and other common contaminants.

Effects of microplastics on juveniles of the common goby (Pomatoschistus microps): confusion with prey, reduction of the predatory performance and efficiency, and possible influence of developmental conditions

Microplastics (MP) are ubiquitous contaminants able to cause adverse effects on organisms. Three hypotheses were tested here: early Pomatoschistus microps juveniles can ingest MP; the presence of MP may reduce fish predatory performance and efficiency; developmental conditions may influence the preyselection capability of fish. Predatory bioassays were carried out with juveniles from two estuaries with differences in environmental conditions: Minho (M-est) and Lima (L-est) Rivers (NW Iberian coast). Polyethylene MP spheres (3 types) alone and in combination with Artemia nauplii were offered as prey.All the MP types were ingested, suggesting confusion with food. Under simultaneous exposure to MP and Artemia, L-est fish showed a significant reduction of the predatory performance (65%) and efficiency (upto 50%), while M-est fish did not, suggesting that developmental conditions may influence the preyselection capability of fish. The MP-induced reduction of food intake may decrease individual and population fitness.

Variability in antioxidant/detoxification enzymes of Labeo rohita exposed to an azo dye, acid black (AB)

The aim of the present study was to evaluate effect of a highly toxic azo dye, acid black (AB) (CI: 20470, 96 h LC50=10 mg/L) on the biochemical responses of Labeo rohita. Antioxidant/detoxification enzymes such as glutathione-S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), acetylcholinesterase (AChE), lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), acid phosphatase (AcP), alkaline phosphatase (AKP), alanine transaminase (ALT) and aspartate transaminase (AST) were determined in liver, kidney, gill, muscle and brain of L. rohita after 96 h exposure to 6 mg/L (LC10), 8 mg/L (LC30) and 10 mg/L (LC50) of dye with an aim to find out the target tissue and biomarker enzyme for AB. The fish were then kept for a recovery period of 90 days, and activity of the selected enzymes was determined at the end of this period. Present dye altered the activities of all these enzymes in the selected tissues of the experimental fish in a dose-dependent manner. SOD was the maximally affected enzyme, and liver was the most affected tissue. The results indicate that AB is very toxic to L. rohita as there was a significant effect of even 6 mg/L dose of the dye and the toxicity prolonged for a long time because the fish was not able to recover from the stress even 90 days after the exposure. The study suggests that SOD can be used as a biomarker enzyme and liver is the target tissue for AB.

Sensitivity of the sea snail Gibbula umbilicalis to mercury exposure--linking endpoints from different biological organization levels

Mercury contamination is a common phenomenon in the marine environment and for this reason it is important to develop cost-effective and relevant tools to assess its toxic effects on a number of different species. To evaluate the possible effects of Hg in the sea snail Gibbula umbilicalis, animals were exposed to increasing concentrations of the contaminant in the ionic form for 96 h. After this exposure period, mortality, feeding and flipping behavior, the activity of the biomarkers glutathione S-transferase, superoxide dismutase, catalase, lactate dehydrogenase and cholinesterase, the levels of lipid peroxidation and cellular energy allocation were measured. After 96 h of exposure to the highest Hg concentration (≈LC20), there was a significant inhibition of the cholinesterase activity as well as impairment in the flipping behavior and post-exposure feeding of the snails. Cholinesterase inhibition was correlated with the impairment of behavioral responses also caused by exposure to Hg. These endpoints, including the novel flipping test, revealed sensitivity to Hg and might be used as relevant early warning indicators of prospective effects at higher biological organization levels, making these parameters potential tools for environmental risk assessment. The proposed test species showed sensitivity to Hg and proved to be a suitable and resourceful species to be used in ecotoxicological testing to assess effects of other contaminants in marine ecosystems.

Biomarkers of endocrine disruption in juveniles and females of the estuarine fish Pomatoschistus microps

The presence of endocrine disruptor chemicals (EDCs) in aquatic compartments, including estuaries, has been object of major concern. However, the effects of EDCs on autochthonous estuarine fish species are far less known than in freshwater fish. Therefore, the response of biomarkers in the estuarine fish Pomatoschistus microps was evaluated after 21-days of exposure to different EDCs: 17β-estradiol (E2); PCB-77 and p,p'DDE. In juveniles, Vtg (vitellogenin)-like proteins were significantly induced by E2. PCB-77 led to a decrease of Vtg-like proteins in juveniles, while in female liver they increased at the highest concentrations tested, suggesting a mode of action of PCB-77 that depends on the fish life stage. p,p'-DDE did not induce significant changes in Vtg-like proteins. Overall, P. microps juveniles seemed to respond to environmental relevant concentrations of EDCs. Thus, the evaluation of Vtg-like proteins in this life stage seems to be a promising tool to track EDC contamination in biomonitoring studies.

Involvement of the antioxidant system in differential sensitivity of Carcinus maenas to fenitrothion exposure

Carcinus maenas is an invertebrate with worldwide distribution and high ability to adapt to different environments, which is frequently used in environmental monitoring. Despite this, it is not clear how historical exposure to moderate contamination may influence sensitivity to further chemical stress in this important decapod species. This study investigated differential responses to organophosphate fenitrothion of C. maenas from a moderately contaminated estuary and a low impacted one, using in vitro and in vivo biomarker assays. To clarify potential differences in sensitivity, a biochemical characterisation of muscle cholinesterases was first performed. The results indicated acetylcholinesterase (AChE) as the main form present in C. maenas muscle. Exposure assays revealed that crabs from the moderately contaminated site were less sensitive to fenitrothion showing lower AChE inhibition than those from the low impacted site. Other biomarker changes detected in these animals were: increased anaerobic metabolism (muscle lactate dehydrogenase), enhanced phase II biotransformation (glutathione S-transferases in the digestive gland) and antioxidant defences (i.e., activities of glutathione reductase, glutathione peroxidase and catalase, and levels of total glutathiones in the digestive gland). Altogether, the results pointed out a role for the glutathione redox system towards tolerance to fenitrothion exposure.

Multivariate analysis applied to agglomerated macrobenthic data from an unpolluted estuary

We agglomerated species into higher taxonomic aggregations and functional groups to analyse environmental gradients in an unpolluted estuary. We then applied non-metric Multidimensional Scaling and Redundancy Analysis (RDA) for ordination of the agglomerated data matrices. The correlation between the ordinations produced by both methods was generally high. However, the performance of the RDA models depended on the data matrix used to fit the model. As a result, salinity and total nitrogen were only found significant when aggregated data matrices were used rather than species data matrix. We used the results to select a RDA model that explained a higher percentage of variance in the species data set than the parsimonious model. We conclude that the use of aggregated matrices may be considered complementary to the use of species data to obtain a broader insight into the distribution of macrobenthic assemblages in relation to environmental gradients.

Evaluation of in vitro and in vivo toxic effects of newly synthesized benzimidazole-based organophosphorus compounds

This paper reports the toxic properties of eight newly synthesized benzimidazole-based organophosphorus (OP) compounds in Xenopus laevis in both in vivo and in vitro conditions. For both experiments, a commercial solution of azinphos methyl (AzM, Gusathion M WP25) was used as a reference compound. The 24-h median lethal concentrations (LC₅₀) of all tested compounds were determined for 46th stage tadpoles in the range of 9.54-140.0 μM. For evaluation of the lethality of the compounds, the activity of the enzyme biomarkers acetylcholinesterase (AChE), carboxylesterase, glutathione S-transferase (GST), glutathione peroxidase, glutathione reductase, lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase were determined in vivo in X. laevis tadpoles exposed to three concentrations (LC₅₀, LC₅₀/2, and LC₅₀/4) of tested compounds. All exposure concentrations of AzM and seven of eight tested compounds caused CaE inhibition in in vivo conditions. Furthermore, the AChE inhibition capacity of tested compounds in commercial electric eel AChE and in X. laevis homogenates and also CaE inhibition capacity in only X. laevis homogenates were assayed for a 30-min in vitro exposure period. Eight OP compounds did not inhibit AChE activity more than 23 percent, but AzM exposure inhibited AChE activity by 26 percent for X. laevis homogenates and 97 percent for electric fish AChE in in vitro conditions. Also, CaE inhibition levels in X. laevis tadpole homogenates were 46 percent for AzM and between 8 percent and 33 percent for other compounds in in vitro conditions.

Evaluation of spatial and temporal changes in biomarker responses in the common carp (Cyprinus carpio L.) for biomonitoring the Meriç Delta, Turkey

The aim of this study is to examine the activity of several biomarkers in carp, Cyprinus carpio L., to determine their response to xenobiotics, such as organochlorine pesticides (OCPs), in the Meriç Delta. Fish were collected from contaminated sites and from areas regarded as relatively less contaminated in four sampling periods. Hepatic glutathione S-transferase (GST), carboxylesterase (CaE), lactate dehydrogenase, aspartate aminotransferase, and acid phosphatase activities were measured as biomarkers in the fish. For all fish, the condition factor and hepatosomatic index, were calculated to determine the condition of the fish. The results of this study indicated that the mean GST activity showed an increase in fish from the Meriç-Ergene junction site and a decrease in Enez site with respect to fish from Meriç site. Furthermore, the study shows that spatial and temporal changes of biomarkers such as GST and CaE might be useful for the assessment of environmental contamination in the Meriç Delta.

Biochemical response of anthracene and benzo [a] pyrene in milkfish Chanos chanos

Polycyclic aromatic hydrocarbons (PAHs) are common toxic pollutants found in the aquatic environment, and the assessment of their impact on biota is of considerable concern. The aim of the present research was to study the acute toxicity, bioaccumulation and biochemical response of milkfish Chanos chanos (Forsskal) to two selected PAHs: anthracene and benzo [a] pyrene. Acute toxicity test results were evaluated by the Probit analysis method and 96h LC(50) values for C. chanos exposed to anthracene was 0.030mgl(-1) and 0.014mgl(-1) for benzo [a] pyrene. Bioaccumulation concentration of anthracene was high when compared to benzo [a] pyrene. Biomarkers indicative of neurotoxicity (acetylcholinesterase, AchE), oxidative stress (lipid peroxidation, LPO and catalase, CAT) and phase II biotransformation of xenobiotics (glutathione S transferase, GST and reduced glutathione, GSH) were measured to assess effects of selected PAHs. Anthracene and benzo [a] pyrene increase LPO and CAT level of C. chanos suggesting that these PAHs may induce oxidative stress. Both the PAHs inhibited AchE indicating that they have at least one mechanism of neurotoxicity in common: the disruption of cholinergic transmission by inhibition of AChE. An induction of C. chanos glutathione S-transferase (GST) activity was found in fish exposed to benzo [a] pyrene, while an inhibition was observed after exposure to anthracene. These results suggest that GST is involved in the detoxification of benzo [a] pyrene, but not of anthracene.

Health status of Pomatoschistus microps populations in relation to pollution and natural stressors: implications for ecological risk assessment

Effects induced on wild populations by recurrent environmental contamination may difficult the ecological risk assessment of punctual pollution events such as oil spills. Here, the issue was addressed by comparing the health status of Pomatoschistus microps populations from four NW Iberian estuaries, using an integrated chemical-biological monitoring. Despite high seasonal variability, the parameters measured discriminated estuaries with different contamination levels and associated biological effects with chemical and abiotic stress. The decreased health status of fish from polluted sites strengthens the need of considering pollution-induced background effects and seasonal variability when assessing impacts and risks of oil and other chemical spills.

Short-term variability of multiple biomarker response in fish from estuaries: Influence of environmental dynamics

Short-term variability in biomarker responses and the effects of temperature and salinity variation were explored in three fish species (Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps) occurring in the Tejo estuary. Short-term variability in biomarkers was observed in all species although no pattern was discerned over time (days to weeks). Antioxidant enzymes activity (superoxide dismutase (SOD) and catalase (CAT)) showed low temporal variability, indicating some constancy or baseline level in antioxidant responses. Only CAT activity in S. senegalensis was correlated with temperature, suggesting that exposure to contaminants triggered antioxidant acclimation. Higher short-term variability was observed in xenobiotic biotransformation enzymes activity (phase I ethoxyresorufin O-deethylase (EROD) and phase II glutathione S-transferase (GST)). Yet a significant correlation between EROD and GST in D. labrax and S. senegalensis suggests a concomitant response to contaminants. Moreover the lack of correlation between xenobiotic biotransformation enzymes and abiotic variables on concordant time scales, suggest a high specificity of these biomarkers to chemical exposure, rather than high variability due to environmental dynamics.

Effects of pulp and paper mill effluent extracts on liver anaerobic and aerobic metabolic enzymes in rainbow trout

This study investigates whether pulse exposure to Chilean pulp and paper mill effluent solid phase extracted (SPE) extracts via intraperitoneal injection (IP), would result in changes in the activities of the respiratory metabolic enzymes citrate synthase (CS) and lactate dehydrogenase (LDH) in rainbow trout livers. It also investigated if an alteration in liver metabolic capacity influenced the liver detoxification processes and estrogenic effects previously reported. Besides, a comparison of those enzymatic activities with fish IP injected with SPE extracts of two model effluents coming from industries that process 100% different type of feedstock (softwood, SW and hardwood, HW) was also evaluated. An initial induction of the anaerobic metabolism (increase in LDH enzymatic activity) was detected in all Chilean pulp mill effluent extracts evaluated, contrary to the initial unaltered aerobic metabolism (CS enzymatic activity) observed. A compensatory relationship in energy metabolism (Pasteur effect) was observed when comparing both enzymatic activities of fish exposed to those effluent extracts. LDH and CS activities observed in fish injected with Chilean extracts seem to be related to the effects observed in fish injected with SW extracts. This study showed that intraperitoneal injection of pulp and paper mill effluent extracts affected the anaerobic and aerobic metabolic capacities in rainbow trout livers, but this metabolic alteration did not affect detoxification capability or estrogenic effect previously reported.

Multi-biomarker responses to estuarine habitat contamination in three fish species: Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps

Several biomarker responses were determined in three fish species, Dicentrarchus labrax, Solea senegalensis and Pomatoschistus microps, from two estuaries of the Portuguese coast, Ria de Aveiro and Tejo. Both estuaries have significant anthropogenic influences from multiple sources (industrial, agricultural and shipping activities), which was evident from sediment chemical characterization concerning metal (copper, zinc, nickel, lead and chromium) and polycyclic aromatic hydrocarbon (PAH) concentrations. Spatial variability in fish responses was observed across species for most biomarkers of exposure [the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST), and metallothionein concentrations (MT)] and effect biomarkers [lipid peroxidation (LPO), RNA to DNA ratio (R:D), protein and lipid content]. In general, the interspecific differences in biomarker responses were greater than the spatial differences, due to differences in the behavior and habitat use of the species. Nevertheless, similarities were also observed considering both chemical load and biomarker responses. In highly polluted sites fish showed in general a significant antioxidant enzyme induction, associated with decreased R:D values, while fish from the least impacted site had little enzyme induction and better condition indices (high R:D and low LPO values). EROD activity was also higher for all species in the Tejo than Ria de Aveiro estuary, despite the generally higher total PAH measured in Ria de Aveiro, most likely due to a higher proportion of 4 and 6-ring PAHs, considered more toxic than low molecular weight PAHs, in the Tejo. In conclusion, this multi-biomarker approach considering multiple species provided improved understanding of the diverse responses and effects of exposure to contaminants and the effective risk it poses for different fish species.

Effects of exposure to PAHs on brain AChE in gilthead seabream, Sparus aurata L., under laboratory conditions

The purpose of this research was to assess the effects of exposure to selected PAHs (phenanthrene, pyrene, and fluorene) on brain acetylcholinesterase (AChE) in juvenile gilthead seabream (Sparus aurata) in short term in vivo experiments. The measured brain AChE activity was within the same range (110-200 nmol min(-1) mg prot(-1)) in all the considered treatment conditions and in the control. The only statistically significant difference in AChE activity with respect to the control group was its induction in response to the lowest tested pyrene concentration in one of two replicated studies. These results suggest that exposure to PAHs does not appreciably affect brain AChE activity.

Comparative study about the effects of pollution on glass and yellow eels (Anguilla anguilla) from the estuaries of Minho, Lima and Douro Rivers (NW Portugal)

The health status of eels (Anguilla anguilla) developing in three estuaries of the NW Portuguese coast with different types and levels of pollution was compared in relation to morphometric parameters, Fulton condition index (F index) and several biomarkers. Relatively to the reference population, glass eels from the Lima estuary had lower weight and length, cholinesterase (ChE) and lactate dehydrogenase (LDH) inhibition, and lower levels of some anti-oxidant parameters, while yellow eels also showed a decreased F index, and increased Na(+)/K(+)-ATPase and lipid peroxidation (LPO) levels. Relatively to the reference population, glass eels from the Douro estuary had increased Na(+)/K(+)-ATPase and glutathione-S-transferase activities and LDH inhibition, while yellow eels also had ChE inhibition and increased LPO. Overall, these results indicate that eels from polluted estuaries showed a poor health status than those from a reference estuary, and that adverse effects become more pronounced after spending several years in polluted estuaries.

Monitoring pollution of coastal lagoon using Liza aurata kidney oxidative stress and genetic endpoints: an integrated biomarker approach

Despite the importance of fish kidney in several functions (immune, metabolism and excretion of xenobiotics) its use in coastal water biomonitoring focusing on protection and damage is scarce. Five critical sites in Ria de Aveiro (Portugal; Barra--BAR, Gafanha--GAF, Rio Novo do Principe--RIO; Laranjo--LAR and Vagos--VAG) were assessed in comparison to a reference site (Torreira--TOR), focusing on Liza aurata kidney antioxidant defences versus damage responses. Non protein thiols were higher at RIO (near a former bleached kraft pulp mill effluent) and total glutathione at RIO, LAR (mercury contaminated) and VAG (polycyclic aromatic hydrocarbons contaminated). Catalase and glutathione S-transferase activities were higher at RIO and LAR whereas no differences were found in glutathione peroxidase activity. However, glutathione reductase was higher at BAR (subject to naval traffic), GAF (harbour water area), RIO and LAR. No peroxidative damage was observed despite the decreased DNA integrity at RIO and VAG. The integrated biomarker response index ranked impacted sites as: LAR>RIO>BAR>GAF>VAG>TOR.

Factors influencing epibenthic assemblages in the Minho Estuary (NW Iberian Peninsula)

The epibenthic community of the Minho Estuary was studied during the summer of 2006. Diversity was generally low and a total of 14 fish and five crustacean taxa were identified. Multivariate analysis revealed two site clusters (A and B). Water conductivity and percentage of fine sand were the abiotic variables that most contributed to the spatial distinction between clusters. The species contributing the most to the average similarity within Cluster A were Crangon crangon and Pomatoschistus microps, while in Cluster B was Atyaephyra desmarestii. Possible factors responsible for the low diversity of the epibenthic community in Minho Estuary were the low macrozoobenthic abundance and diversity, and the high abiotic oscillations between tides (mainly salinity) acting on the ecosystem.

Localization and properties of cholinesterases in the common prawn (Palaemon serratus): A kinetic-histochemical study

Due to the diversity in biochemical properties and tissue distribution of cholinesterase (ChE) enzymes, a characterization should be performed before they are used as biomarkers for monitoring pesticide contamination. In this study we investigate the distribution of ChEs and their kinetic properties in diverse tissues of the common prawn Palaemon serratus. The results concerning the histochemical localization of ChEs suggest that the highest amount of ChE activity occurs in prawn eyes, followed by the brain, gills, and digestive tract. Negligible staining was observed in the muscle. We describe the kinetic properties of ChEs in eyes, gills, and hepatopancreas, investigating their substrate preferences with different thiocholine esters and their sensitivity to inhibition with selective inhibitors. The results suggest that the studied enzymes are ChEs and not nonspecific esterases, due to their apparent affinity for choline esters, with a distinct preference for the substrate acetylthiocholine, and their high sensitivity to inhibition by eserine sulfate. P. serratus eyes can be considered the best tissue for recovery of ChE enzyme: this tissue is easy to isolate, it expresses high levels of ChE, and the enzyme shows properties of a vertebrate AChE.

Yellow eel (Anguilla anguilla) development in NW Portuguese estuaries with different contamination levels

The aims of the present study were to compare the health status of yellow eels (Anguilla anguilla) developing in three estuaries of the NW Portuguese coast with different levels of pollution and their physiological responses to combined effects of environmental variation and pollution. For this, a field study was performed using a multi-parameter approach, including eels condition indexes and biomarkers, water quality variables and other environmental factors. Sixteen biological parameters were assessed, namely: hepatosomatic index (LSI), Fulton's condition index (K), lipid peroxidation (LPO), total glutathione (TG), reduced glutathione (GSH), oxidised glutathione (GSSG), GSH/GSSG, and the activity of the enzymes acetylcholinesterase (AChE), lactate dehydrogenase (LDH), sodium-potassium ATPase (Na(+)/K(+)-ATPase), ethoxyresorufin O-deethylase (EROD), glutathione S-transferases (GST), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR). Ten environmental factors were also measured in water: temperature, salinity, pH, phosphates, nitrates, nitrites, ammonium, silica, phenol and hardness. Globally, the biomarkers indicate exposure and toxic effects of pollutants on eels living in contaminated estuaries. The relationships between biological and environmental variables were assessed through redundancy analysis. K and LSI indexes, AChE and Na(+)/K(+)-ATPase, total glutathione levels and the antioxidant enzymes CAT, GR, and SOD where the factors most discriminating reference (Minho River estuary) from contaminated estuaries (Lima and Douro Rivers estuaries). Moreover, the most striking outcomes of pollutants exposure on biological responses were observed during winter, probably due to a joint effect of cold weather and pollution stress. Altogether, the results indicate that the development of eels in the polluted estuaries of Lima and Douro rivers is interfering with physiological functions determinant for their survival and performance. This may increase the mortality rates during the continental life-phase of the species and decrease the percentage of animals able to successfully complete their oceanic migration and, thus, reduce the contribution of each generation to the next one.

Contamination assessment of a coastal lagoon (Ria de Aveiro, Portugal) using defence and damage biochemical indicators in gill of Liza aurata--an integrated biomarker approach

Fish gill importance in toxicants uptake, bioconcentration and excretion allied to meagre knowledge on branchial damage/protection responses substantiate this study. Five critical sites in Ria de Aveiro (Portugal) were assessed in comparison with a reference site (Torreira), focusing on Liza aurata gill antioxidant defences versus damage (oxidative and genetic). Only in Barra fish displayed damage (lipid peroxidation) though no differences were found in antioxidants. In all other sites, except Rio, antioxidant alterations were found. Thus, fish from Gafanha, Laranjo and Vagos showed higher total glutathione, glutathione peroxidase and catalase. Higher glutathione reductase and glutathione S-transferase activity was also found in the first and the last sites, respectively. In Laranjo, metallothionein levels were higher though lower in Gafanha and Vagos. In general, damage was not accompanied by defences weakening confirming that predicting damage based on antioxidants depletion is not straightforward. The integrated biomarker response index ranked sites as: Gafanha>Barra>Laranjo>Vagos>Rio>Torreira.

Evaluation of three-year monitoring with biomarkers in fish following the Prestige oil spill (N Spain)

A previous study using a suite of hepatic enzymatic biomarker in two demersal fish species (Lepidorhombus boscii and Callionymus lyra) indicated exposure of the fish to the hydrocarbons in the oil spilled by the Prestige five months after the accident. The main objective of this follow-up study is to determine whether the same biomarkers in both fish species show any significant variations in responses over the years following the Prestige oil spill. Detoxification and antioxidant enzyme measurements--of ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), glutathione reductase (GR) and catalase (CAT)--were taken from immature specimens. The results show significant lowering of biomarker activity two and three-years after the oil spill, indicating a decreasing level of exposure of the fish to residual hydrocarbons associated with the spillage (p < 0.01) and a recovery to baseline levels existing before the accident. Overall, spatial biomarker patterns over time are in agreement with the oil slick trajectories and the spatial distribution of tar aggregates found on the bottom shelf after the accident. The results also indicate that the Prestige oil spill had an impact on sublethal responses in fish not only in inshore areas, but also in offshore areas along the middle/outer northern Iberian shelf. In both species, EROD activity was found to be the most discriminating biomarker.

Acute effects of Benzo[a]pyrene, anthracene and a fuel oil on biomarkers of the common goby Pomatoschistus microps (Teleostei, Gobiidae)

The objective of this study was to investigate the effects of two different PAHs and a complex petrochemical mixture on the common goby, Pomatoschistus microps, using selected biomarkers as effect criteria. Benzo[a]pyrene (BaP) and anthracene were used as reference substances, while the water accommodated fraction of #4 fuel-oil (#4 WAF) was used as an example of a petrochemical mixture. P. microps was used since it is both a suitable bioindicator and a good test organism. Groups of fish were exposed to different concentrations of each of the test substances for 96 h and the activities of several enzymes commonly used as biomarkers were determined at the end of the bioassays. All the substances inhibited P. microps acetylcholinesterase (AChE) indicating that they have at least one mechanism of neurotoxicity in common: the disruption of cholinergic transmission by inhibition of AChE. An induction of lactate dehydrogenase (LDH) activity was found in fish exposed to BaP or to anthracene, suggesting an increase of the anaerobic pathway of energy production. On the contrary, inhibition of LDH was found in fish exposed to #4 WAF, suggesting a distinct effect of the mixture. An induction of P. microps glutathione S-transferase (GST) activity was found in fish exposed to BaP or to #4 WAF, while an inhibition was observed after exposure to anthracene. These results suggest that GST is involved in the detoxification of BaP and #4 WAF, but not of anthracene. All the substances increased catalase activity and isolated PAHs also increased superoxide dismutase, glutathione reductase and glutathione peroxidase activities, while #4 WAF did not cause significant alterations on these enzymes. These results suggest that all the substances may induce oxidative stress on P. microps, with BaP and anthracene apparently having more oxidative stress potential than #4 WAF.

Transport and acclimation conditions for the use of an estuarine fish (Pomatoschistus microps) in ecotoxicity bioassays: effects on enzymatic biomarkers

Acclimation of organisms for ecotoxicity testing is in general processed according to Organisation for Economic Co-operation and Development (OECD) and/or Environmental Protection Agency (EPA) guidelines, under controlled conditions. However, when organisms are collected in the field, their capture, transport and adaptation to laboratory conditions are factors of stress. In their natural habitat, estuarine fish are exposed to considerable fluctuations of environmental variables, while in laboratory they are acclimated to constant conditions and this can be per se a factor of stress that may influence biomarker responses. Therefore, it is important to investigate the effects of these procedures on estuarine fish performance before using them as test organisms in ecotoxicity bioassays. The goal of the present study was to investigate the effects of transporting the common goby, Pomatoschistus microps from the field (natural populations) to the laboratory and of its acclimation to laboratory conditions on the enzymes acetylcholinesterase (AChE), lactate dehydrogenase (LDH) and glutathione S-transferases (GSTs). Fish were collected in a reference site of the Minho River estuary (NW of Portugal) and the activities of the biomarkers were monitored before and after the transport of organisms to the laboratory and during the acclimation period (at 5, 10 and 15 days). The activities of all the enzymes indicated that capture and transport conditions had no effects on enzymatic activities. Furthermore, AChE, LDH and GST presented higher activities at the end of the acclimation period than at beginning, suggesting a physiological adaptation to laboratory conditions. This adaptation should be taken into consideration in the experimental design to avoid bias in the interpretation of effects of xenobiotics on biomarkers.

Neurotoxic effect and metabolic responses induced by a mixture of six pesticides on the earthworm Aporrectodea caliginosa nocturna

The effects of a mixture of insecticides and/or fungicides at different environmental concentrations were investigated on a Aporrectodea caliginosa nocturna population. This laboratory experiment was carried out in order to reproduce Gaillac (France) vineyard conditions. Neurotoxicity (cholinesterase), metabolisation (glutathione-S-transferase) and oxidative stress (catalase) enzymes were studied as biomarkers in earthworms after short-term exposure in terraria. The aim was to observe the global effects of pesticide exposure, as in a vineyard, rather than focus on each isolated biomarker variation, or on each compound's impact. ChE activity was inhibited after a few days of insecticide and/or fungicide exposure, indicative of a neurotoxic effect in earthworms. The significant increase in GST and CAT activities revealed the metabolisation of these products resulting in the production of reactive oxygen species. After a long period of exposure or high concentrations, earthworms were physiologically damaged: they could not cope with the high toxicity (cellular dysfunction, protein catabolism...). Chemical analysis showed that pesticide bioaccumulation in earthworm tissues, even in those exposed to the highest concentrations and for the longest periods, was very low (under LOD) or absent. However, the study of pesticide residues in terraria after 34 days in a climate chamber suggested that earthworms participate in soil pesticide breakdown.

Esterases activities and lipid peroxidation levels in muscle tissue of the shanny Lipophrys pholis along several sites from the Portuguese Coast

This study is part of a project aiming to validate the use of the intertidal shanny Lipophorys pholis as a sentinel species in pollution monitoring in NW European marine ecosystems. To this end, a characterisation of acethylcholin (AChE), butyrylcholin (BChE) and propionylcholin (PrChE) esterases in L. pholis muscle was performed and the results indicated that AChE was predominant. Furthermore, the use of eserine sulphate and BW284c51 (0.64-800 microM), and iso-OMPA (0.08-16 mM), confirmed the measurement of true cholinesterases (ChEs) as well as the presence of pseudocholinesterases. The field application of these markers to L. pholis, sampled in seven locations along the Portuguese coast, revealed that fish were likely to be affected by neurotoxic compounds. This was indicated by the significant depletion of AChE (p<0.05) in animals collected at urban and industrialised sites, compared with those from reference locations. The inclusion of a marker of effect, measured as lipid peroxidation levels in muscle tissue, also revealed the existence of site differences. Overall, the study further validates the utility of L. pholis in pollution monitoring studies.