Biochemical responses of the shore crab (Carcinus maenas) in a eutrophic and metal-contaminated coastal system (Obidos lagoon, Portugal)

Assessment of metal contamination in an urbanized estuary (Atlantic Ocean) using crabs as biomonitors: A multiple biomarker approach

Estuarine environments, which are complex and sensitive coastal system, and are the final receptacle of several human wastes. Consequently, biomonitoring contaminants, such as metals, within these environments and developing scientific-based tools to conserve them have become particularly importat in recent years. Therefore, in the present study, we determined the levels of certain metals (Cd, Cu, Pb, Zn, Mn, Ni, Cr and Fe) both in sediments and in a key ecological benthic species, the burrowing crab Neohelice granulata, in sites of the Bahía Blanca estuary (SW Atlantic Ocean) with different anthropogenic impacts. We combined these records with geochemical indices and enzymatic and non-enzymatic biochemical biomarkers as early warning signals of contamination and damage to establish an integrated metal contamination profile. Our results indicated that some metals like Cu moderately contaminate the estuary and that the primary input of metals in this area is due to malfunctioning sewage discharges. Crabs exhibited the following pattern of metal accumulation: Fe ≥ Cu > Zn > Mn > Ni > Cd. Pb and Cr were under the method detection limit, and Cu was probably bioaccumulated from sediments. Metal concentrations showed significant differences according to the sites and seasons (p > 0.05) and not strictly to the crab gender. Besides, a similar pattern was observed for biomarkers, and the integrated biomarker response allowed establishing different oxidative stress patterns, according not only to human impacts but also to the seasonal physiological needs of this species and environmental endpoints (salinity, temperature, and pH). This work demonstrates that environmental factors also affect the metal influx in crabs and the activity of biomarkers beyond the source and fate of these elements. This information is vital for future integrated monitoring programs.

First long-term assessment of metals and associated ecological risk in subtidal sediments of a human-impacted SW Atlantic estuary

The main objective of this article was to profile the metal accumulation, sources, pollution levels and trends during 6 years in a SW Atlantic coastal system (Bahía Blanca estuary). Subtidal sediment samples were taken from six stations with different human impacts, and chemical element analyses were performed using ICP-OES. As a result, metals tended to increase in time and differences were observed between a site profoundly impacted by sewage waters and the rest of the sampling stations. Values range from background levels to those considered toxic for the marine biota, as in the case of Cd and Cu. Besides, the geochemical analyses exhibited low to moderate pollution with probable adverse biological effects. Finally, the physicochemical parameters of the water column like pH and DO significantly decreased in time in all stations and temperature correlated with some metals, indicating a potential interaction.

Metal Bioaccumulation and Oxidative Stress in Ulva laetevirens in the Venice Lagoon: Early Warning Biomarker for Metal Bioaccumulation

Transitional water systems (TWSs) may be threatened by various metals originating from increased agricultural, industrial activities, or urban effluents. Macroalgae are one of the biological quality elements used to monitor and assess the health status of TWS due to their structural and functional key role in marine ecosystems. Here, metal accumulation from the macroalgae Ulva laetevirens Areschoug (1854) and oxidative stress by lipid peroxidation (LPO) biomarker were investigated during four sampling seasons from three sampling sites (SMM: Santa Maria del Mare; PM: Porto Marghera; SG: San Giuliano) of Venice Lagoon, affected by different anthropogenic stressors. The metal pollution index (MPI) scores for U. laetevirens increased in the order SMM < PM < SG (sea inlet < industrial area < Osellino River estuary), with average values per site of 2.99, 4.37, and 6.33, respectively. The level of LPO was statistically correlated with the concentration of toxic metal(loid)s (As, Pb, Hg) measured in macroalgae, and seasonality affected both levels of LPO and metal bioaccumulation, with peak values during spring and summer. These findings highlighted the efficiency and usefulness of the oxidative stress test (LPO) on the common macroalga U. laetevirens as an early warning signal for health assessment in aquatic ecosystems.

Integrative assessment of the ecological risk of heavy metals in a South American estuary under human pressures

Biomonitoring of heavy metal pollution through the use of biomarkers could be a difficult task since the organisms' physiological changes could shift regarding natural factors (i.e., the season of the year) and due to the anthropogenic pressures of the environment. In the Southwest Atlantic Ocean, where most industrial and developing countries are settled, it is essential to address these concerns to generate information for the stakeholders and monitoring programs that aim to use biochemical biomarkers as early warning signals to detect heavy metal pollution. The present study intended to determinate the heavy metal concentrations in sediments and the hepatopancreas of the crab species Neohelice granulata as well as the ecological risk through the use of biomarkers and geochemical indices in sites with different anthropogenic pressures of the Bahía Blanca estuary (SW Atlantic Ocean) during the warm and cold season. The results showed low to moderate heavy metal pollution in the sediments by Cu with possible effects on the biota in a site with sewage waters' discharges. Except for GST that was explained by Cd, the biomarkers employed were not useful to assess spatial heavy metal pollution, and they might be ruled out by physiological seasonal variations rather than anthropogenic constraints, or another type of pollutants in the area.

Enzymatic and non-enzymatic detoxification in Lycosa terrestris and Pardosa birmanica exposed to single and binary mixture of copper and lead

Organisms employ various enzymatic and non-enzymatic detoxification mechanisms to minimize the harmful effects of metal pollution in the terrestrial environment. We examined the effects of copper (Cu), lead (Pb) and their mixture (Cu + Pb) on glutathione (GSH), metallothionein (MTs), cytochrome P450 (CYP 450), carboxylesterase (CarbE), acetylcholinesterase (AchE) and glutathione S-transferase (GST) in Lycosa terrestris and Pardosa birmanica via two exposure routes, i.e., soil and food for 10, 20 and 40 days. The present results revealed that the accumulation of Cu and Pb in both spiders' species increase with exposure duration and depend on the route of exposure and type of metal. The activities of CarbE, GST, and MTs significantly increased with increasing metal body burden for all experimental treatments. The CYP 450 activity exhibited a significant time-dependent decrease with increasing Cu concentration in both species. The AchE activity was significantly inhibited on Pb exposure via soil and Cu + Pb exposure via both routes. The decrease in the level of GSH was measured on Cu + Pb exposure via both routes. Thus, all these enzymatic and non-enzymatic responses are sensitive to the metals tested and could serve as early warning indicators for assessing the effects of metal pollution in these species.

Modulation of antioxidant gene expressions by Roundup® exposure in the decapod Macrobrachium potiuna

Glyphosate-based herbicides (GBH), including Roundup®, are the most used herbicides in agricultural and non-agricultural areas, which can reach aquatic environments through drift during application or surface runoff. Some studies, mostly in fish, demonstrated that GBH caused oxidative stress in non-target animals. However, only few information is available on the GBH effects in the antioxidant and stress proteins of many other organisms, such as freshwater crustaceans. Thus, we aimed to investigate the effects of environmentally relevant GBH concentrations on the relative transcript expression (RTE) of the superoxide dismutase (sod1), catalase (cat), selenium-dependent glutathione peroxidase (gpx), glutathione-S-transferase (gst), thioredoxin (txn), heat shock protein (hsp70 and hsp90) in the hepatopancreas of the ecologically important freshwater prawn Macrobrachium potiuna. Moreover, this study aimed to assess the gender-differences responses to GBH exposure. Male and female prawns were exposed to three Roundup WG® concentrations (0.0065, 0.065 and 0.28 mg of glyphosate/L) and a control group (0.0 mg/L) for 7 and 14 days. In general, males had an under-expression of the studied genes, indicating an oxidative stress and possible accumulation of ROS in the hepatopancreas. In the opposite, females had an overexpression of the same genes, indicating a more robust antioxidant system, in order to cope with the possible ROS increase after Roundup WG® exposure. Therefore, results confirmed that gender could be a confounding factor in ecotoxicological assessment of GBH effects. Additionally, this work highlights that sod1, cat, gpx, gst, txn, hsp70 and hsp90 gene expressions seem to be useful biomarkers to investigate the oxidative stress caused by Roundup WG® in Macrobrachium sp.

Wastewater bioremediation by mangrove ecosystems impacts crab ecophysiology: In-situ caging experiment

Mangroves are tidal wetlands that are often under strong anthropogenic pressures, despite the numerous ecosystem services they provide. Pollution from urban runoffs is one such threats, yet some mangroves are used as a bioremediation tool for wastewater (WW) treatment. This practice can impact mangrove crabs, which are key engineer species of the ecosystem. Using an experimental area with controlled WW releases, this study aimed to determine from an ecological and ecotoxicological perspective, the effects of WW on the red mangrove crab Neosarmatium africanum. Burrow density and salinity levels (used as a proxy of WW dispersion) were recorded, and a 3-week caging experiment was performed. Hemolymph osmolality, gill Na⁺/K⁺-ATPase (NKA) activity and gill redox balance were assessed in anterior and posterior gills of N. africanum. Burrow density decreased according to salinity decreases around the discharged area. Crabs from the impacted area had a lower osmoregulatory capacity despite gill NKA activity remaining undisturbed. The decrease of the superoxide dismutase activity indicates changes in redox metabolism. However, both catalase activity and oxidative damage remained unchanged in both areas but were higher in posterior gills. These results indicate that WW release may induce osmoregulatory and redox imbalances, potentially explaining the decrease in crab density. Based on these results we conclude that WW release should be carefully monitored as crabs are key players involved in the bioremediation process.

Monitoring metal pollution on coastal lagoons using Cerastoderma edule-a report from a moderately impacted system in Western Portugal (Óbidos Lagoon)

The main goal of this monitoring program was to evaluate the contamination in the intertidal environment of Óbidos Lagoon by the metals Cd, Pb, and Ni on water, sediments, and on biological samples, using the bivalve Cerastoderma edule (common name: cockle) as a biomonitor. Since C. edule is an edible mollusc, the risk of their consumption by humans from this lagoon was also evaluated. The study was performed in a restricted area of the lagoon-the ML station-where human activities, such as shellfish harvesting, intersect with the natural processes occurring in this system. The results obtained revealed that the water samples were polluted with Cd and Pb with concentrations (0.00025 mg l^-1 and 0.0072 mg l^-1) above the maximum legislated on the Directive 2008/105/EC, while for Ni, this occurred only on one of the seasons sampled (summer 2010: 0.029 mg l^-1). The sediments were not contaminated with Cd and Ni, and the contamination detected for the metal Pb, allowed the classification of this station as an unpolluted site ([Pbmin] = 7.477 mg.kg^-1 and [Pbmax] = 19.875 mg.kg^-1). On biological samples, comparing the results of metal contaminations with the values of the maximum levels fixed by European Commission Regulation (EC) No 1881/2006 and USFDA, all the results were below the legal value. Therefore, during the period of study, the consumption of this bivalve by humans was safe. Also, BAF and CF calculations suggest that C. edule can be used as a biomonitor to determine the source of the contaminations. This study supported the use of C. edule as a biomonitor to assess the contamination by the metals Pb and Ni at the Óbidos Lagoon and allowed to predict the potential transfer of metals to higher trophic levels with potential impacts on the natural and human communities.

Joint toxicity on hepatic detoxication enzymes in goldfish (Carassius auratus) exposed to binary mixtures of lead and paraquat

Compared to single exposure, chemical mixtures might induce joint toxicity including additive, synergistic and antagonistic effects on both organisms and environment. Owing to the specific toxicity of oxidative stress and binding to proteins, lead (Pb) is generally recognized a non-essential and threatening heavy metal to animals and human. Paraquat (PQ) is a widely used herbicide in agriculture and can trigger oxidative stress as well as Pb. Little information was available about joint effects of the two chemicals on toxicological responses in organisms, especially in fish. In our present study, goldfish (Carassius auratus) were randomly exposed to single and combined experiments with different concentrations of Pb and PQ for 28 days. Activities of four enzyme biomarkers in liver, ethoxyresorufin-O-deethylase (EROD), 7-benzyloxy-4-trifluoromethyl-coumarin-O-debenzyloxylase (BFCOD), glutathione-S-transferase (GST) and UDP-glucuronosyltransferase (UGT) were evaluated in each experimental group on day 14 and 28. The results showed four enzyme levels were markedly reduced with the increase of concentrations in mixtures and prolonged exposure. The inhibitory EROD and BFCOD activities were not significantly changed in goldfish following PQ-treated groups with or without 0.5 mg/L Pb, which indicated PQ has more inhibitory toxicity on CYP450 enzymes than Pb in co-exposure groups. However, the reduced values of GST were observed only in the combinations containing high doses of Pb or PQ during experimental periods. Although the responses of UGT activity were similar to GST on 14th day, all combinations of Pb and PQ generated stronger inhibitions on UGT activities compared to individual Pb and PQ-treated group. These results suggested that combined exposure of Pb and PQ have more inhibitory toxicity on phase I enzymes than phase II enzymes.

A baseline study of the metallothioneins content in digestive gland of the Norway lobster Nephrops norvegicus from Northern Adriatic Sea: Body size, season, gender and metal specific variability

Metallothioneins content was investigated in digestive gland of two wild-caught Norway lobster Nephrops norvegicus populations from the Northern Adriatic Sea, in relation to body size, season and gender. Concomitant accumulation of cadmium, mercury, arsenic, lead, chromium and manganese, reactive oxygen species concentration and energy reserves in digestive gland were also assessed. While differences between genders were not recorded, metallothioneins content seasonal trends were affected by body size. Most of parameters displayed inconsistent trends across sampling sites. Significant correlation between metallothioneins content and cadmium, arsenic and mercury concentrations was recorded only for larger lobsters. A negative correlation of reactive oxygen species concentration and metallothioneins content was observed for small, but not large lobsters. Energy reserves, in particular lipids, could considerably influence biochemical and chemical parameters variations. The present results constitute the essential baseline for future studies aimed at evaluating the N. norvegicus health in relation to metal contamination of coastal sediments.

Phytochelatins and monothiols in salt marsh plants and their relation with metal tolerance

Phytochelatins (PCs) and monothiols and their relation with trace element concentrations were studied in three plant species from two Portuguese salt marshes. Belowground tissues showed always higher element concentrations, while enhanced values of monothiols were found in aboveground biomass. Glutathione was usually the most abundant monothiol. The concentration of total PCs was higher in leaves or stems than in roots of Halimione portulacoides and Sarcocornia perennis, while in Spartina maritima the highest concentrations were reported in large roots. PC₂ was synthesized by all tissues and species and was higher in large roots of S. maritima. PC₄ and PC₅ were in high levels in small roots of S. maritima. PC₂ was positively correlated with As, Zn and Pb. Although being the first evidence of PCs and monothiols in these species under natural conditions, our results do not point to a simple relationship with elements concentrations, suggesting a complex mechanism involved.

Biomarker responses to environmental contamination in estuaries: A comparative multi-taxa approach

Estuaries are highly productive ecosystems subjected to numerous anthropogenic pressures with consequent environmental quality degradation. In this study, multiple biomarker responses [superoxide dismutase (SOD), catalase (CAT), ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST) activities, as well as lipid peroxidation (LPO) and DNA damage (DNAd)] were determined in two fish (Dicentrarchus labrax and Pomatoschistus microps) and four macroinvertebrate species (Carcinus maenas, Crangon crangon, Hediste diversicolor and Scrobicularia plana) from the Ria de Aveiro and Tejo estuaries over distinct months. Two sites per estuarine system were selected based on anthropogenic pressures and magnitude of environmental contamination. Antioxidant enzyme activities in fish species suggested a ubiquitous response to oxidative stress, while biotransformation and effect biomarkers exhibited higher spatial and temporal variation. In invertebrate species, biotransformation enzyme activity was clearly less variable than in fish evidencing lower xenobiotic transformation capability. Overall, largest biomarker responses were found in the most contaminated sites (Tejo), yet species-specific patterns were evident. These should be factored in multi-taxa approaches, considering that the differential functional traits of species, such as habitat use, life-stage, feeding or physiology can influence exposure routes and biomarker responses. The Integrated Biomarker Response index highlighted patterns in biomarker responses which were not immediately evident when analyzing biomarkers individually. Overall, results provided insights into the complexity of species responses to contamination in naturally varying estuarine environments. Ultimately, multi-taxa and multi-biomarker approaches provide a comprehensive and complementary view of ecosystem health, encompassing diverse forms of biological integration and exposure routes, and allow the validation of results among markers and species.

Metals from mine waste as potential cause of oxidative stress in burrowing crab Neohelice granulata from San Antonio bay

The Natural Protected Area San Antonio bay is of particular importance for its congregation of migratory shorebirds and it has been declared one of the Western Hemisphere Shorebird Reserve Network International site (WHSRN). Present study represents the first assessment of variation on oxidative stress biomarkers in male crab Neohelice granulata from San Antonio bay (Río Negro, Argentina) under field conditions, associated mainly to metal contamination coming from passive mining wastes. Three sites were sampled once every three months from November 2012 to August 2013 within this sea inlet (Pile, Fishery and Port) and a control site at the southeast of the bay (Punta Perdices). Accumulation of Ni, Zn, Cr and Al varied only with seasons although without a constant trend, meanwhile Cd, Cu and Pb also varied among sites being highest in Pile and Port. Biochemical results indicated that variations in catalase activity was only site specific being maximum in Pile; meanwhile lipid radical, α-tocopherol and metallothioneins were only seasonal specific being higher in autumn and winter. Seasonal variation was also found for total thioles, being the content higher in summer and autumn than in winter. Correlation analysis revealed that malondialdehyde and α-tocopherol have a positive association with Al and negative with Ni, meanwhile GST has a positive association with Fe. Crabs from the closest area to the waste pile did not exhibit a differentiated oxidative pressure despite the higher accumulation of metals. It is possible that crabs from contaminated areas have developed a tolerance to metals, indicating a strong ecotoxicological selective pressure. More studies are needed to assess whether there is a transfer of metals through the food chain.

Effect of temperature on oxidative stress parameters and enzyme activity in tissues of Cape River crab (Potamanautes perlatus) following exposure to silver nanoparticles (AgNP)

Biomarkers of oxidative stress have been widely used in environmental assessments to evaluate the effects of exposure of aquatic organisms to contaminants from various anthropogenic sources. Silver nanoparticles (AgNP), the most produced NP worldwide and used in several consumer products, are known to produce oxidative stress in aquatic organisms. Similarly, temperature is also known to affect reactive oxygen species (ROS) by influencing the inputs of contaminants into the environment, as well as altering behavior, fate, and transport. Aquatic ecosystems are affected by both anthropogenic releases of contaminants and increased temperature. To test this hypothesis, the influence of AgNP and temperature in the response to multiple biomarkers of oxidative stress was studied in the gills and hepatopancreas of the Cape River crab Potamonautes perlatus. Responses were assessed through activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and the nonenzymatic antioxidant glutathione S-transferase (GST). The response of the oxidative stress biomarkers analyzed was always higher in hepatopancreas than in gills. Elevated temperatures (28°C) induced oxidative stress by increasing SOD, CAT, and GST activities, particularly at 100 µg/ml AgNP. These data indicate that AgNP-mediated toxicity to P. perlatus is modulated by elevated temperatures, but this relationship is not linear. Co-effects of AgNP and temperature are reported for the first time in P. perlatus.

Laboratory simulation system, using Carcinus maenas as the model organism, for assessing the impact of CO2 leakage from sub-seabed injection and storage

The capture and storage of CO2 in sub-seabed geological formations has been proposed as one of the potential options to decrease atmospheric CO2 concentrations in order to mitigate the abrupt and irreversible consequences of climate change. However, it is possible that CO2 leakages could occur during the injection and sequestration procedure, with significant repercussions for the marine environment. We investigate the effects of acidification derived from possible CO2 leakage events on the European green crab, Carcinus maenas. To this end, a lab-scale experiment involving direct release of CO2 was conducted at pH values between 7.7 and 6.15. Female crabs were exposed for 10 days to sediment collected from two different coastal areas, one with relatively uncontaminated sediment (RSP) and the other with known contaminated sediment (MZ and ML), under the pre-established seawater pH conditions. Survival rate, histopathological damage and metal (Fe, Mn, Cu, Zn, Cr, Cd and Pb) and As accumulation in gills and hepatopancreas tissue were employed as endpoints. In addition, the obtained results were compared with the results of the physico-chemical characterization of the sediments, which included the determination of the metals Fe, Mn, Cu, Zn, Cr, Pb and Cd, the metalloid As, certain polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), as well as nonchemical sediment properties (grain size, organic carbon and total organic matter). Significant associations were observed between pH and the histological damage. Concentrations of Fe, Mn, Cr, Pb, Cd and PAHs in sediment, presented significant negative correlations with the damage to gills and hepatopancreas, and positive correlations with metal accumulation in both tissues. The results obtained in this study reveal the importance of sediment properties in the biological effects caused by possible CO2 leakage. However, a clear pattern was not observed between metal accumulation in tissues and pH reduction. Animals' avoidance behavior and degree of tolerance to acidification are confounding factors for assessing metal bioaccumulation. Further research is required to find a suitable assay that would allow us to predict the risk to environmental health of possible negative side effects of metal mobility derived from CO2 leakage during its injection and storage in sub-seabed formations.

Priority Substances and Emerging Organic Pollutants in Portuguese Aquatic Environment: A Review

Aquatic environments are among the most noteworthy ecosystems regarding chemical pollution due to the anthropogenic pressure. In 2000, the European Commission implemented the Water Framework Directive, with the aim of progressively reducing aquatic chemical pollution of the European Union countries. Therefore, the knowledge about the chemical and ecological status is imperative to determine the overall quality of water bodies. Concerning Portugal, some studies have demonstrated the presence of pollutants in the aquatic environment but an overall report is not available yet. The aim of this paper is to provide a comprehensive review about the occurrence of priority substances included in the Water Framework Directive and some classes of emerging organic pollutants that have been found in Portuguese aquatic environment. The most frequently studied compounds comprise industrial compounds, natural and synthetic estrogens, phytoestrogens, phytosterols, pesticides, pharmaceuticals and personal care products. Concentration of these pollutants ranged from few ng L(-1) to higher values such as 30 μg L(-1) for industrial compounds in surface waters and up to 106 μg L(-1) for the pharmaceutical ibuprofen in wastewaters. Compounds already banned in Europe such as atrazine, alkylphenols and alkylphenol polyethoxylates are still found in surface waters, nevertheless their origin is still poorly understood. Beyond the contamination of the Portuguese aquatic environment by priority substances and emerging organic pollutants, this review also highlights the need of more research on other classes of pollutants and emphasizes the importance of extending this research to other locations in Portugal, which have not been investigated yet.

The presence of cadmium in the intertidal environments of a moderately impacted coastal lagoon in western Portugal (Óbidos Lagoon)--spatial and seasonal evaluations

A seasonal environmental monitoring program was carried out (winter 2009 to summer 2010) to evaluate the spatial and seasonal cadmium concentrations in the intertidal environments of the Óbidos Lagoon (Portugal). Also, some environmental parameters were monitored at each sampling station. Both the water and the sediment samples were contaminated, although to different degrees. In general, cadmium contamination appears to be mostly focused on the inner areas of the lagoon, namely, in Barrosa's arm, which receives a small tributary contaminated by agro-industrial activities. Only cadmium concentration in sediment showed to be significantly influenced by seasons. Some environmental parameters presented spatial and temporal heterogeneity which influenced, to some extent, cadmium bioavailability. The results of this study allow a better understanding of the environmental quality of this ecosystem regarding cadmium contamination and may assist in the definition of future coastal management measures specifically targeted to trace metal contamination and pollution monitoring.

Glutathione S-transferase activities in African catfish injected with β-naphthoflavone: effects of ploidy, gender, dose, and sampling time

Glutathione S-transferases (GST) are considered among the most controversial biomarkers of water pollutants in fish with little known about factors influencing their activities. The objective of this study was to investigate how gender, dose, ploidy, and sampling time alter hepatic GST activities in African catfish (Clarias gariepinus) following β-naphthoflavone (β-NF) injection. Newly matured male and female diploid and triploid fish were intraperitoneally (i.p.) injected with 0, 15, or 75 mg/kg of β-NF, and livers were excised 24, 48, and 72 h post-injection. Results showed that hepatic GST activities were significantly inhibited by both doses of β-NF. Inhibition was greater in females than males, but no significant differences were observed between diploid and triploid fish. Enzymatic activities differed over time with lowest levels 72 h post-injection. These results extend our understanding of GST activity in fish and highlight the necessity of considering confounding factors when comparing different studies.

Biochemical performance of native and introduced clam species living in sympatry: The role of elements accumulation and partitioning

The present study reports metal and arsenic contamination in sediments, as well as element accumulation and partitioning in native (Ruditapes decussatus and Venerupis corrugata) and introduced (Ruditapes philippinarum) clam species living in sympatry at the Óbidos lagoon (Portugal). The biochemical performance and the human health risks derived from the consumption of these species are also discussed. The results obtained showed that R. decussatus was the most abundant species in all the sampling sites, revealing that the introduced clam has not yet supplanted the native species. The concentration of elements was higher in areas with higher Total Organic Matter (TOM) and fines content, being Chromium (Cr), Copper (Cu) and Lead (Pb) the most abundant metals. Clams from these areas showed the highest concentration of elements but the lowest bioaccumulation levels. Furthermore, except for As, higher concentration of elements was found in clams insoluble fraction, the less toxic fraction to the organisms. Due to the low contamination levels and because elements, except As, were mainly allocated to the insoluble fraction, clams presented similar biochemical parameters among distinct areas, with no significant oxidative stress induced. Furthermore, clams from the Óbidos lagoon represent a low health risk to human consumption since, except for As, their contamination levels were below the maximum permissible limits defined by international organizations.

Integrated biomarker responses of an estuarine invertebrate to high abiotic stress and decreased metal contamination

An integrated chemical-biological effects monitoring was performed in 2010 and 2012 in two NW Iberian estuaries under different anthropogenic pressure. One is low impacted and the other is contaminated by metals. The aim was to verify the usefulness of a multibiomarker approach, using Carcinus maenas as bioindicator species, to reflect diminishing environmental contamination and improved health status under abiotic variation. Sampling sites were assessed for metal levels in sediments and C. maenas, water abiotic factors and biomarkers (neurotoxicity, energy metabolism, biotransformation, anti-oxidant defences, oxidative damage). High inter-annual and seasonal abiotic variation was observed. Metal levels in sediments and crab tissues were markedly higher in 2010 than in 2012 in the contaminated estuary. Biomarkers indicated differences between the study sites and seasons and an improvement of effects measured in C. maenas from the polluted estuary in 2012. Integrated Biomarker Response (IBR) index depicted sites with higher stress levels whereas Principal Component Analysis (PCA) showed associations between biomarker responses and environmental variables. The multibiomarker approach and integrated assessments proved to be useful to the early diagnosis of remediation measures in impacted sites.

The cytotoxic and genotoxic effects of metalaxy-M on earthworms (Eisenia fetida)

As the main optical isomer of metalaxyl, metalaxyl-M has been widely used worldwide in recent years because of its notable effect on the prevention and control of crop diseases. Together with the toxicity and degradation of metalaxyl-M, the chemical has attracted the attention of researchers. The present study examined the toxic effects of metalaxyl-M on earthworms at 0 mg kg(-1) , 0.1 mg kg(-1) , 1 mg kg(-1) , and 3 mg kg(-1) on days 7, 14, 21 and 28 after exposure. The results showed that metalaxyl-M could cause an obvious increase in the production of reactive oxygen species (ROS) when the concentration was higher than 0.1 mg kg(-1) , which led to lipid peroxidation in earthworms. Metalaxyl-M can induce DNA damage in earthworms, and the level of DNA damage markedly increased with increasing the concentration of metalaxyl-M. Metalaxyl-M also has a serious influence on the activities of antioxidant enzymes, which results in irreversible oxidative damage in cells. The changes of these indicators all indicated that metalaxyl-M may cause cytotoxic and genotoxic effects on earthworms.

The crab Carcinus maenas as a suitable experimental model in ecotoxicology

Aquatic ecotoxicology broadly focuses on how aquatic organisms interact with pollutants in their environment in order to determine environmental hazard and potential risks to humans. Research has produced increasing evidence on the pivotal role of aquatic invertebrates in the assessment of the impact of pollutants on the environment. Its potential use to replace fish bioassays, which offers ethical advantages, has already been widely studied. Nevertheless, the selection of adequate invertebrate experimental models, appropriate experimental designs and bioassays, as well as the control of potential confounding factors in toxicity testing are of major importance to obtain scientifically valid results. Therefore, the present study reviews more than four decades of published research papers in which the Green crab Carcinus maenas was used as an experimental test organism. In general, the surveyed literature indicates that C. maenas is sensitive to a wide range of aquatic pollutants and that its biological responses are linked to exposure concentrations or doses. Current scientific knowledge regarding the biology and ecology of C. maenas and the extensive studies on toxicology found for the present review recognise the Green crab as a reliable estuarine/marine model for routine testing in ecotoxicology research and environmental quality assessment, especially in what concerns the application of the biomarker approach. Data gathered provide valuable information for the selection of adequate and trustworthy bioassays to be used in C. maenas toxicity testing. Since the final expression of high quality testing is a reliable outcome, the present review recommends gender, size and morphotype separation in C. maenas experimental designs and data evaluation. Moreover, the organisms' nutritional status should be taken into account, especially in long-term studies. Studies should also consider the crabs' resilience when facing historical and concurrent contamination. Finally, experimental temperature and salinity should be harmonised so as to obtain reliable comparisons between different studies. Concerning future reaserch areas, data gathered in the present review reveals that in vitro assays derived from C. maenas are still lacking. Also, a complete C. maenas genome sequencing programme will be essencial for cutting-edge reseach.

Metabolic enzyme activities, metabolism-related genes expression and bioaccumulation in juvenile white shrimp Litopenaeus vannamei exposed to benzo[a]pyrene

The purpose of this study was to investigate the impact of benzo[a]pyrene (BaP) on metabolic detoxification system and bioaccumulation of white shrimp Litopenaeus vannamei. In this study, juvenile white shrimp L. vannamei were exposed for 21 days at four different concentrations of 0, 0.03, 0.3 and 3μg/L. Detoxification enzyme activities of phase I (aryl hydrocarbon hydroxylase (AHH), 7-ethoxyresorufin O-deethylase (EROD), epoxide hydrolase (EH)) and phase II (glutathione-S-transferase (GST), sulfotransferase (SULT), uridine diphosphate glucuronyl transferase (UGT)) were determined, and results showed that all the detoxification enzyme activities increased in a dose-dependent manner except for the low BaP exposure. Transcription of genes was detected and measured by real-time RT-PCR. It showed that at day six BaP increased cytochrome P450 (CYP) 1A1, GST, SULT visa aryl hydrocarbon receptor (AhR) mRNA expression in a dose-dependent manner, which suggests that they could be potential targets of BaP that disrupt the detoxification system. The consistency of their responses to BaP exposure implies that AhR action may be involved in invertebrate CYP regulation. Additionally, BaP bioaccumulation increased rapidly first and showed an incoming plateau. Besides, the enzyme activities and bioaccumulation in the hepatopancreas were higher than those in the gills. These results will not only provide information on BaP metabolic mechanism for this species, but also scientific data for pollution monitoring.

Overview on the European green crab Carcinus spp. (Portunidae, Decapoda), one of the most famous marine invaders and ecotoxicological models

Green crabs (Carcinus, Portunidae) include two species native to Europe--Carcinus aestuarii (Mediterranean species) and Carcinus maenas (Atlantic species). These small shore crabs (maximal length carapace, approximately 10 cm) show rapid growth, high fecundity, and long planktonic larval stages that facilitate broad dispersion. Carcinus spp. have a high tolerance to fluctuations of environmental factors including oxygen, salinity, temperature, xenobiotic compounds, and others. Shipping of Carcinus spp. over the past centuries has resulted in its invasions of America, Asia, and Australia. Classified as one of the world's 100 worst invaders by the International Union for Conservation of Nature, Carcinus spp. are the most widely distributed intertidal crabs in the world. Their voracious predatory activity makes them strong interactors in local communities, and they are recognized as a model for invasiveness in marine systems as well as a sentinel species in ecotoxicology. This review shows an exhaustive analysis of the literature on the life cycle, diversity, physiological tolerance, genomic investigations, ecotoxicological use, historical invasion, control programs, and putative economical valorization of shore crabs.

Ecotoxicity of silver nanomaterials in the aquatic environment: a review of literature and gaps in nano-toxicological research

There has been extensive growth in nanoscale technology in the last few decades to such a degree that nanomaterials (NMs) have become a constituent in a wide range of commercial and domestic products. With NMs already in use in several consumer products, concerns have emerged regarding their potential adverse environmental impacts. Although research has been undertaken in order to minimise the gaps in our understanding of NMs in the environment, little is known about their bioavailability and toxicity in the aquatic environment. Nano-toxicology is defined as the study of the toxicity of nanomaterials. Nano-toxicology studies remain poorly and unevenly distributed. To date most of the research undertaken has been restricted to a narrow range of test species such as daphnids. Crabs are bio-indicators that can be used for toxicological research on NMs since they occupy a significant position in the aquatic food chain. In addition, they are often used in conventional ecotoxicological studies due to their high sensitivity to environmental stressors and are abundantly available. Because they are benthic organisms they are prone to contaminant uptake and bioaccumulation. To our knowledge the crab has never been used in nano-toxicological studies. In this context, an extensive review on published scientific literature on the ecotoxicity of silver NPs (AgNPs) on aquatic organisms was conducted. Some of the most common biomarkers used in ecotoxicological studies are described. Emphasis is placed on the use of biomarker responses in crabs as monitoring tools, as well as on its limitations. Additionally, the gaps in nano-toxicological research and recommendations for future research initiatives are addressed.

Biochemical effects in crabs (Carcinus maenas) and contamination levels in the Bizerta Lagoon: an integrated approach in biomonitoring of marine complex pollution

The biochemical effects in Carcinus maenas and contamination levels in seawater and sediments of Bizerta Lagoon (northeast of Tunisia) were investigated. The levels of metals and hydrocarbons were higher in seawater and sediments in Menzel Bourguiba and Cimentery in February and July than in the other sampling sites. Differences among sites for glutathione S-transferase, catalase, acetylcholinesterase activities, and the content of lipid peroxidation and metallothioneins in two important organs which accumulated contaminants (the gills and the digestive gland) of the C. maenas were found and possibly related to differences in metal and hydrocarbon levels. The seasonal variation of biomarkers was possibly associated with chemical contamination and also with the high fluctuation of physico-chemical characteristics of the sites. The integrated biomarker response values found in the five sites is in good agreement with hydrocarbon and trace metal concentrations detected in the water and sediments of the stressful places where crabs are living.

Biochemical responses and physiological status in the crab Hemigrapsus crenulatus (Crustacea, Varunidae) from high anthropogenically-impacted estuary (Lenga, south-central Chile)

Estuarine environmental assessment by sub-individual responses is important in order to understand contaminant effects and to find suitable estuarine biomonitor species. Our study aimed to analyze oxidative stress responses, including glutathione-S-transferase (GST) activity, total antioxidant capacity (ACAP) and lipid peroxidation levels (TBARS) in estuarine crabs Hemigrapsus crenulatus from a high anthropogenically-impacted estuary (Lenga) compared to low and non-polluted estuaries (Tubul and Raqui), in a seasonal scale (winter-summer), tissue specific (hepatopancreas and gills) and sex related responses. Results showed that hepatopancreas in male crabs better reflected inter-estuary differences. Morpho-condition traits as Cephalothorax hepatopancreas index (CHI) could be used as an indicator of physiological status of estuarine crabs. Discriminant analysis also showed that GST and TBARS levels in summer are more suitable endpoints for establishing differences between polluted and non-polluted sites. These results suggest the importance of seasonality, target tissue, sex and physiological status of brachyuran crabs for estuarine biomonitoring assessment.

Exposure of Carcinus maenas to waterborne fluoranthene: accumulation and multibiomarker responses

Fluoranthene (FLU) is a priority polycyclic aromatic hydrocarbon (PAH) commonly detected in estuarine sediments, water and biota. Despite this, information on FLU detection, accumulation and effects on marine crustaceans is scarce. This work investigated the accumulation of FLU in Carcinus maenas and the responses of several early-warning biomarkers after a 7-day laboratory exposure to five FLU concentrations (2.56 to 100 μg L(-1)). After exposure to FLU, sub-samples of the crabs' digestive gland and muscle were collected for biomarker determinations. The remaining digestive gland and muscle, together with the rest of the whole-body soft tissues, were analysed for FLU residues by gas chromatography-mass spectrometry (GC-MS). The biomarkers assessed were: i) the quantification of FLU-type compounds by fixed wavelength fluorescence (FF); ii) the activities of glutathione S-transferases (GST) and glutathione reductase (GR), and the levels of total glutathione (GT) and lipid peroxidation (LPO) for oxidative stress; iii) the activity of acetylcholinesterase (AChE) for neurotoxicity; iv) the activities of isocitrate dehydrogenase (IDH) and lactate dehydrogenase (LDH) enzymes, and total protein, glycogen and lipids as indicators of changes in energy metabolism and storage; and v) the lysosomal membrane stability (LMS) as a measure of cell damage. The results showed strong (R(2)>0.95) concentration-dependent accumulation of FLU residues (as measured by GC-MS) in the remaining whole-body soft tissues and of FLU-type compounds (as measured by FF) in the digestive gland and muscle. A strong positive linear relationship (R(2)=0.91) between FLU residues and FLU-type compounds was also found. Comparing to controls, activities of GST and GR were significantly higher in crabs exposed to ≥16 and ≥40 μg L(-1) FLU, respectively. TG levels and IDH activity showed a significant trend to increase with FLU concentrations whereas AChE activity exhibited the opposite trend. FF measurements in the digestive gland and muscle proved to be an expeditious cost-effective method to assess the uptake and availability of FLU and its metabolites in C. maenas. The results suggest that under continuous environmental exposure, FLU may enhance detoxification and anti-oxidant defences, and cause alterations in the aerobic energy pathway, as well as neuromuscular toxic effects that may increase C. maenas risk of predation.

Environmental quality assessment combining sediment metal levels, biomarkers and macrobenthic communities: application to the Óbidos coastal lagoon (Portugal)

Macroinvertebrate benthic communities are one of the key biological components considered for the assessment of benthic integrity in the context of the Water Framework Directive (WFD). However, under moderate contamination scenarios, the assessment of macrobenthic alterations at community level alone could be insufficient to discriminate the environmental quality of coastal and transitional waters. Keeping this in view, sediment quality of moderately contaminated sites in a coastal lagoon (Óbidos lagoon, Portugal) was assessed by the combination of sediment metal levels, Carcinus maenas biomarkers (accumulated metals and oxidative stress responses) and macrobenthic communities. Two sites were selected in confined inner branches (BS and BB) and a third one in the middle lagoon (ML). The site BB presented slightly higher levels of metals in sediment but biological variables calculated for macrobenthic data were not significantly different between sites. The biotic index M-AMBI that is being applied to assess environmental quality of transitional waters in the scope of the WFD pointed either to high (site ML) or good quality status (BS and BB) in the selected sites. However, crabs from BB site presented significantly higher levels of Ni in hepatopancreas than those from ML and macrobenthic community structure was significantly different between BB and ML. Additionally, spatial differences were obtained for oxidative stress parameters suggesting that BB site presented stressors for crabs (higher GST and lower GSH(t) at BB site). Factor analysis (PCA) integrating sediment contamination, biomarkers in crabs and macrobenthic data also distinguished BB site as the most environmentally disturbed. On the other hand, at ML site, some macrobenthic variables (equitability and polychaetes' diversity) were found to be enhanced by current environmental conditions, suggesting the existence of a better sediment quality. Current results pointed to the usefulness of integrating macrobenthic community alterations with responses at organism level (bioaccumulation and biochemical endpoints) in order to increase the accuracy of environmental quality assessment in lagoon systems. Moreover, the application of different statistical methods was also found to be recommendable.

Evaluation of EROD and CYP3A4 activities in earthworm Eisenia fetida as biomarkers for soil heavy metal contamination

In this study, the effects of heavy metals (Cd, Cu, Pb, Zn) on EROD and CYP3A4 activities in the earthworm Eisenia fetida were evaluated to find out their possible induction and potential as biomarkers for soil heavy metal contamination. The earthworms were exposed to increasing concentrations of Cd (0.1-8 mg L(-1)), Cu (10-200 mg L(-1)), Pb (20-400 mg L(-1)) or Zn (50-400 mg L(-1)) in filter papers for 48 h. EROD activity was significantly changed in dose-dependent manners after exposure to each of the four metals. CYP3A4 activity was significantly induced by Cd and Pb, rather by Cu and Zn. This is the first report on heavy metal-induced changes of CYP3A4 activity in earthworms. Among the four heavy metals, Cd was the most potent inducing EROD and CYP3A4. While EROD and CYP3A4 activities showed a similar trend, EROD is more sensitive than CYP3A4 activity in E. fetida as a biomarker for heavy metals pollution.

Benthic community structure and biomarker responses of the clam Scrobicularia plana in a shallow tidal creek affected by fish farm effluents (Rio San Pedro, SW Spain)

The effects of solid organic wastes from a marine fish farm on sediments were tested using benthic community as ecological indicators and biomarkers in native clam (Scrobicularia plana) as biochemical indicators. The benthic fauna and clam samples were collected in the intertidal sediment in October 2010 from five sites of the Rio San Pedro (RSP) creek, following a gradient of contamination from the aquaculture effluent to the control site. Numbers of species, abundance, richness and Shannon diversity were the biodiversity indicators measured in benthic fauna. Morphological and reproduction status of clams were assessed using the condition factor and gonado-somatic index, respectively. Phase I and Phase II detoxification enzymatic activities (ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST)), antioxidant enzymatic activities (glutathione peroxidase (GPX), glutathione reductase (GR)) and oxidative stress parameters (Lipid Peroxidation (LPO) and DNA strand breaks) were measured in clams' digestive gland tissues. In parallel, temperature and salinity in the adjacent water, redox potential, pH and organic matter in sediment, and dissolved oxygen in the interstitial water were measured. The results suggested that RSP showed a spatial gradient characterised by hypoxia/anoxia, reduced potential, acidic conditions and high organic enrichment in sediments at the most contaminated sites. Significant (p<0.05) decrease of biodiversity indicators were observed in the areas impacted by the aquaculture discharges. Biomarkers did not show a clear pattern and of all biochemical responses tested, GPX, DNA damage and LPO were the most sensitive ones and showed significant (p<0.05) increase in the polluted sites. Benthic biodiversity indicators were significantly (p<0.05) positively correlated with pH, redox potential and dissolved oxygen and negatively correlated with organic matter. On the contrary, antioxidant enzymatic responses (GPX) and oxidative stress parameters were significantly (p<0.05) negatively correlated with those physico-chemical parameters. It has been demonstrated that effluents from fish aquaculture activities in Río San Pedro creek may produce an alteration of physico-chemical characteristics of seabed and induce oxidative stress and DNA damage in soft-sediment species which may lead to changes of the benthic population structure and health status of the exposed organisms.

Heavy-metal concentrations in soft tissues of the burrowing crab Neohelice granulata in Bahía Blanca estuary, Argentina

Copper (Cu), cadmium (Cd), and chromium (Cr) in soft tissues of male and female burrowing crab Neohelice granulate, as well as their eggs, were measured in two different locations in the Bahía Blanca estuary, a moderately polluted ecosystem, from October 2008 to August 2009. Differences between sexes, sites, and seasonality were assessed. Furthermore, metal levels in eggs were compared with metal levels in female crabs. The results showed no significant differences for Cu and Cd between sexes (Student t test p > 0.25 for both sites) and sites (two-way analysis of variance: Cu p = 0.82 and Cd p = 0.29). Nevertheless, seasonality was found, with winter having significantly lower concentrations for both metals. The range of Cu concentrations was between 96.92 and 152.18 μg g(-1) dry weight (dw), and the range of Cd concentrations was between 6.09 and 10.41 μg g(-1) dw. Cr concentrations could not be assessed because most of the values were lower than the detection limit. Although heavy metals in sediments were not measured in this study, a bioaccumulation process may be occurring for Cd because levels found during the entire sampling period were greater than levels in sediment from previous years. For Cu, a regulation process may be occurring considering that this is an essential metal and levels of Cu in N. granulata found in this study were between 1 and 2 orders of magnitude greater than levels in sediments. Finally, Cu and Cd levels in eggs were detectable, but they were lower than levels in female crabs. The importance of these findings is linked to the fact that metal accumulation seems to be occurring before hatch. The presence of heavy metals in soft tissues as well as in eggs of N. granulata is of great importance considering that this is a key species within the Bahía Blanca estuary; therefore, it plays a major role in the transference of pollutants to greater trophic levels.

Bioaccumulation and biochemical markers in feral crab (Carcinus maenas) exposed to moderate environmental contamination--the impact of non-contamination-related variables

Moderate contamination is a challenging scenario for ecotoxicologists because of the occurrence of subtle biomarker responses and the increased relevance of non-contamination related variables. This investigative biomonitoring study was performed in a moderately contaminated coastal system (Óbidos lagoon, Portugal) to examine winter-summer variations on biochemical responses and accumulated metals in Carcinus maenas, searching for associations with environmental and biological factors. Males and females were collected in three sites: Barrosa (BB) and Bom-Sucesso (BS) in upper lagoon, and the middle lagoon (ML), closer to the lagoon inlet. Water and sediment were monitored for metals (Cu, Mn, Ni, Cr, Cd). Catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), total glutathione content (GSH(t) ), lipid peroxidation (LPO), and ethoxyresorufin-O-deethylase (EROD), as well as Cu, Mn, Ni, Cr and Cd were measured in the crabs' hepatopancreas. Inter-site differences, though infrequent, pointed to the presence of crab stressors at BB. This was particularly obvious in summer when higher GST as well as lower GSH(t) and EROD were found in females, and accompanied by higher Ni accumulation. Seasonal differences of biochemical responses superimposed spatial variations in line with the contrasting winter-summer conditions regarding water quality and, to a lesser extent, with metal bioaccumulation. CAT, GSH(t) , and LPO were higher in summer, whereas enhancements of GPx and GST were recorded in winter. Winter increases were in agreement with higher availability of metals in water and enhancement of accumulated levels, particularly in females as emphasized by a bioaccumulation index. On the other hand, increases in summer were mainly driven by non-contamination related factors. Males and females exhibited different patterns of metal accumulation and biochemical responses, with females being more responsive, as confirmed by a general stress index (IBR). Results recommend gender separation in biomonitoring programs using crabs. The integration of biochemical responses into IBR substantiated data interpretation. This is particularly relevant under moderate contamination allowing for better site-distinction rather than biochemical responses considered individually.

DNA damage and effects on glutathione-S-transferase activity induced by atrazine exposure in zebrafish (Danio rerio)

This study was undertaken to investigate the protective effect of atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-S-triazine) on the activity of glutathione-S-transferase (GST) and DNA damage in males and females of adult zebrafish (Danio rerio). Zebrafish were exposed to control and three treatments (0.01, 0.1, and 1 mg/L) of atrazine for 5, 10, 15, 20, and 25 days. The results indicated that, for males, the GST activity at lower atrazine concentrations (0.01 and 0.1 mg/L) was markedly higher than that of the controls throughout the duration of the experiment while there was a significant inhibition of the GST activity at 1 mg/L atrazine at days 5 and 20. For females, a significant increase was detected at 0.1 mg/L on the days 5 and 15 and at 0.01 mg/L on day 20. The DNA damage in zebrafish was evaluated using the comet assay; the olive tail moments obtained for hepatopancreas were enhanced after treatment with different concentrations of atrazine on days 5, 10, 15, 20, and 25. The DNA damage increased with increasing atrazine concentrations, indicating that genotoxicity of atrazine and significant differences was found compared to the controls. In conclusion, these findings provide further evidence of the effects of atrazine on aquatic ecosystems.

Biomarker responsiveness in different tissues of caged Ruditapes philippinarum and its use within an integrated sediment quality assessment

Biomarkers comprising activities of biotransformation enzymes (ethoxyresorufin-O-deethylase -EROD-, dibenzylfluorescein dealkylase -DBF-, glutathione S-transferase -GST), antioxidant enzymes (glutathione reductase -GR- and glutathione peroxidase -GPX), lipid peroxidation -LPO- and DNA strand breaks were analyzed in the clam Ruditapes philippinarum caged at Cádiz Bay, Santander Bay and Las Palmas de Gran Canaria (LPGC) Port (Spain). Sediments were characterized. Digestive gland was the most sensitive tissue to sediment contamination. In Cádiz Bay, changes in LPO regarding day 0 were related with metals. In LPGC Port, DBF, EROD, and GST activity responses suggested the presence of undetermined contaminants which might have led to DNA damage. In Santander Bay, PAHs were related with EROD activity, organic and metal contamination was found to be associated with GR and GST activities and DNA damage presented significant (p < 0.05) induction. R. philippinarum was sensitive to sediment contamination at biochemical level. Biomarkers allowed chemical exposure and sediment quality assessment.

The burrowing crab Neohelice granulata as potential bioindicator of heavy metals in estuarine systems of the Atlantic coast of Argentina

This paper presents the concentrations of total copper, lead, cadmium, and zinc in hepatopancreas of the burrowing crab Neohelice granulata from the Samborombón Bay (La Plata River estuary) and the Mar Chiquita coastal lagoon, Argentina. The highest accumulation of lead was observed in Mar Chiquita samples, whereas copper, zinc, and cadmium concentrations were higher in those from Samborombón Bay. Marked temporal and geographic availability differences were observed, while sexual differences only were observed for zinc. Finally, the validity of using this species as bioindicator of heavy-metal pollution within the assessed estuarine ecosystems is discussed.

Integrated assessment of biochemical responses in Mediterranean crab (Carcinus maenas) collected from Monastir Bay, Tunisia

The biochemical response of Mediteranean Crab (Carcinus maenas) collected at five stations of Monastir Bay and from Kuriat station as control was studied using a set of complementary biomarkers. The catalase, glutathione S-transferase, lactate dehydrogenase, acetycholinesterase activities; and metallothionein and malonediladehyde levels in gills were evaluated. Results revealed differences among sites in relation to each specific biomarker. Hence, a suite of biomarkers can be used to discriminate sampling sites according to types of pollution, reflecting differing conditions of anthropogenic impact. Based on Integrated Biomarker Response, the highest values and critical biochemical alteration were observed at Khniss and Ksibat in response to urban and industrial discharges and the lowest IBR value was found at reference site. The current study has shown clearly that a biomarker-based index is usefulness tool in the monitoring Tunisian coast using C. maenas as sentinel specie. Further studies in progress to investigate the seasonal variations of IBR levels and its relationship to pollutants concentrations in the sediment, gills and digestive gland of Carcinus maenas from Monastir Bay.

Daily availability of nutrients and metals in a eutrophic meso-tidal coastal lagoon (Obidos lagoon, Portugal)

This baseline reports daily variations of physico-chemical parameters, nutrients and metals in water of two sites [eutrophic conditions (BB) versus reference (LL)] in Obidos coastal lagoon (Portugal). Dissolved oxygen in BB varied between 40% saturation levels (night) and 190% (daylight). NH(4)(+), PO(4)(3-) and ratios to Al of Mn, Fe and Pb in suspended particulate matter increased during the period of lower oxygenation, indicating exportation of nutrients and metals from the sediment to water at night. At LL, O(2) values oscillated always around 100%. PO(4)(3-) and Mn/Al ratio at LL were always lower than at BB and no increases were found during the night. The input of PO(4)(3-) and Mn provided from the sediment at BB during the night could surpass the contribution of freshwater discharges. PCA confirmed the separation of most samples from BB and LL. These results pointed to the importance of assessing chemical conditions over day-night cycles.

The relevance of temporal and organ specific factors on metals accumulation and biochemical effects in feral fish (Liza aurata) under a moderate contamination scenario

Moderate contamination scenarios are nowadays challenging ecotoxicologists. An investigative biomonitoring study was performed under those environmental conditions (Obidos lagoon, Portugal) focused on oxidative stress and accumulated metals in Liza aurata liver and kidney, also examining winter-summer variations and organ-specificities. Three sites were surveyed: Barrosa; Bom-Sucesso; Middle lagoon. The higher metal availability at Barrosa (in water and sediment) was reflected in both organ burdens, though liver was more responsive. Oxidative stress (both organs) pointed to a pro-oxidant challenge at Barrosa (both seasons), reinforced by a general stress index. In winter, oxidative stress at Barrosa was related with accumulated metals in both organs, while in summer this cause-effect relationship was only established for kidney since changes in liver were linked with non-contaminant related variables. Winter-summer variations were outstanding in liver and kidney oxidative stress endpoints, pointing to the relevance of considering distinct seasons and organs in the assessment of moderately contaminated systems.

Biomarker responses in the bivalve (Chlamys farreri) to exposure of the environmentally relevant concentrations of lead, mercury, copper

Water samples collected from Bohai Bay were determined to describe the distributions of lead, mercury, and copper in this area, indicating that mean values of the three metals were 1.63μg/L, 4.85×10(-2)μg/L, and 2.68μg/L, respectively. Only lead exceeded the first class limit of seawater quality standard in China. Then, antioxidant enzymes, lipid peroxidation, and metabolic enzymes were investigated in bivalves (Chlamys farreri), exposed to three metals at the environmental concentration levels obtained from our investigation. Significantly reduced SOD, CAT and GPx activities, in lead-exposed group were observed and resulted in obvious lipid peroxidation. In contrast, mercury and copper did not show such clear oxidative stresses. In consistent with the oxidative stress variations, exposed only to lead caused a great inhibition on EROD activity. Multi-biomarker responses in bivalve when exposed to lead at the environmentally relevant concentration in Bohai Bay suggested that lead may possess a potential risk in this area.

Influences of sex, habitat, and seasonality on heavy-metal concentrations in the burrowing crab (Neohelice granulata) from a coastal lagoon in Argentina

Cadmium, chromium, copper, and manganese concentrations were determined in hepatopancreas of both sexes as well as in eggs at different embryonic development stages of the burrowing crab Neohelice granulata (Brachyura, Varunidae) from Mar Chiquita Coastal Lagoon, a biosphere reserve from Argentina, during a period of 1 year, to assess the bioaccumulation of metals associated with sex and seasonality. Furthermore, metal levels in associated superficial sediment samples were also determined. Two different "cangrejales," one in a mudflat and another one in a salt marsh, were studied. The results showed high concentrations of copper within the hepatopancreas, which was considered a strong reflection of high exposure of N. granulata to this metal. Metal accumulation in hepatopancreas from both study sites and sexes did not present significant differences, as did seasonality. In this sense, both spring and summer metal levels in hepatopancreas were the greatest. Eggs did not present differences in metal accumulation, with the exception of manganese, between sites or between crabs at different embryonic stages. For this metal, eggs from female crabs inhabiting mudflats showed higher levels than those from inhabiting salt marshes. Moreover, eggs in the late embryonic stage also showed the highest manganese concentrations. Metal levels in sediments, however, were similar in both sites. These are the first results of metal level in biota and sediments in this particular environment. Such results could be used as a baseline for the monitoring of metal levels in future studies in Mar Chiquita Coastal Lagoon.

Combined use of environmental data and biomarkers in fish (Liza aurata) inhabiting a eutrophic and metal-contaminated coastal system - Gills reflect environmental contamination

An investigative biomonitoring study was carried out in a eutrophic coastal system with a moderate contamination by metals (Obidos lagoon, Portugal), combining the evaluation of exposure concentrations with metals accumulation and oxidative stress responses in gills of the golden grey mullet (Liza aurata). Two contrasting seasons (winter and summer) were considered at three sites: Barrosa (BB) and Bom-Sucesso (BS) branches; Middle lagoon (ML). Data on the water column pointed to a higher metals and nutrients availability at BB that was reflected in the higher metal concentrations in gills, particularly in winter. Similarly, oxidative stress responses demonstrated a pro-oxidant challenge at BB (winter and summer), which was corroborated by an integrated biomarker response index (IBR). Metal concentrations in gills were higher in summer than winter, reflecting the increased environmental concentrations in combination with elevated metabolic rates. Catalase (CAT), glutathione-S-transferase (GST), total glutathione (GSH(t)) and lipid peroxidation (LPO) increases observed in winter at BB were related with metal accumulation, while summer enhancement of glutathione peroxidase (GPx), glutathione reductase (GR), GST and GSH(t) was associated with other stressors. Inter-site differences on the basis of IBR were more accentuated in winter. Gills can be considered as an important route of entry for contaminants and were demonstrated to reflect water contamination and are therefore useful in the context of environmental assessment.

Environmental monitoring of Domingo Rubio stream (Huelva Estuary, SW Spain) by combining conventional biomarkers and proteomic analysis in Carcinus maenas

Element load, conventional biomarkers and altered protein expression profiles were studied in Carcinus maenas crabs, to assess contamination of "Domingo Rubio" stream, an aquatic ecosystem that receives pyritic metals, industrial contaminants, and pesticides. Lower antioxidative activities - glucose-6-phosphate and 6-phosphogluconate dehydrogenases, catalase - were found in parallel to higher levels of damaged biomolecules - malondialdehyde, oxidized glutathione -, due to oxidative lesions promoted by contaminants, as the increased levels of essential - Zn, Cu, Co - and nonessential - Cr, Ni, Cd - elements. Utility of Proteomics to assess environmental quality was confirmed, especially after considering the six proteins identified by de novo sequencing through capLC-muESI-ITMS/MS and homology search on databases. They include tripartite motif-containing protein 11 and ATF7 transcription factor (upregulated), plus CBR-NHR-218 nuclear hormone receptor, two components of the ABC transporters and aldehyde dehydrogenase (downregulated). These proteins could be used as novel potential biomarkers of the deleterious effects of pollutants present in the area.

Contaminant effects in shore crabs (Carcinus maenas) from Ria Formosa Lagoon

Defence and damage biomarkers signals were studied in female and male shore crabs Carcinus maenas transplanted between two sites at Ria Formosa Lagoon (South of Portugal). The cross transplantation occurred during 6 days at a hypothetical reference site (Ramalhete), and a contaminated site (Olhão). DNA unwinding technique was used for DNA integrity measurement. General enzymatic antioxidant responses in gills and hepatopancreas (catalase and gills glutathione peroxidase activities increase) showed that cross transplanted crabs (female and male) are suffering from pro-oxidant challenges at the Olhão site. Gills and hepatopancreas glutathione-S-transferase were reduced in both gender crabs transplanted from Ramalhete to Olhão. Metallothioneins induction occurred in crabs transplanted from Ramalhete to Olhão (contaminated by metals and polycyclic aromatic hydrocarbons (PAHs)). However metallothionein differences were also observed towards gender and organ specificities. High gills lipid peroxidation exist in male crabs transplanted from Ramalhete to Olhão, while in females it was the opposite. In both gender crabs from the Olhão site, gills DNA integrity decreased compared to the Ramalhete feral crabs. Moreover, hepatopancreas DNA integrity decreased in male crabs transplanted from Olhão to Ramalhete site which may be related to the environmental conditions (lower contamination levels) revealing the difficulty of selection of reference sites in field studies. Data demonstrated that female and male C. maenas antioxidant defences and damage biomarkers were sensitive to the mixture of contaminants present in these sites as well as good indicators of general stress.