Sea-urchin (Paracentrotus lividus) glutathione S-transferases and cholinesterase activities as biomarkers of environmental contamination

Toxicity of tire particle leachates on early life stages of keystone sea urchin species

Particles from tires are a major fraction of microplastic pollution. They contain a wide range of chemical additives that can leach into the water and be harmful to aquatic organisms. In this study, we investigated the acute toxicity of tire particle leachates in early life stages of three keystone echinoderm species (Paracentrotus lividus, Arbacia lixula, Diadema africanum). Embryos were exposed for 72 h to a range of leachate dilutions, prepared using a concentration of 1 g L-1. Larval growth, abnormal development, and mortality were the measured endpoints. Furthermore, we estimated the activity of glutathione S transferase (GST) and the electron transport system (ETS) in P. lividus. Strong concentration-dependent responses were observed in all species, though with differing sensitivity. The median effect concentrations for abnormal development in P. lividus and A. lixula were 0.16 and 0.35 g L-1, respectively. In D. africanum, mortality overshadowed abnormal development and the median lethal concentration was 0.46 g L-1. Larvae of P. lividus were significantly smaller than the control from 0.125 g L-1, while the other two species were affected from 0.5 g L-1. ETS activity did not change but there was a non-significant trend of increasing GST activity with leachate concentration in P. lividus. Seven organic chemicals and eight metals were detected at elevated concentrations in the leachates. While we regard zinc as a strong candidate to explain some of the observed toxicity, it can be expected that tire particle leachates exhibit a cocktail effect and other leached additives may also contribute to their toxicity. Our results emphasize the importance of multi-species studies as they differ in their susceptibility to tire particle pollution. We found negative effects at concentrations close to projections in the environment, which calls for more research and mitigation actions on these pollutants.

Use of the gonadal tissue of the sea urchin Paracentrotus lividus as a target for environmental contamination by trace metals

Many environmental monitoring works have been carried out using biomarkers as a tool to identify the effects of oil contamination on marine organisms; however, only a few studies have used sea urchin gonadal tissue for this purpose. Within this context, the present work aimed to understand the impact of an oil spill, proposing the use of sea urchin gonadal tissue as a biomarker for environmental contamination by trace metals in the species Paracentrotus lividus. Biometric analysis, quantification analyses of the elements Cd, Pb, Ni, Fe, Mn, Zn, and Cu, as well as histopathological evaluations were performed in gonads of P. lividus collected from an area affected by hydrocarbons, named as impacted shore (IS) and an area not affected, named reference shore (RS). The results showed that carapace diameter (DC), total wet weight (WW), and Cd concentrations in the gonads were significantly influenced by the interaction between the rocky shores of origin, the months of sampling, and by the sex of the individuals. Moreover, from July until September, the levels of Zn and Cd were significantly lower in male than in female gonads. In July (the month of the oil spill), the indexes of histopathological alterations (IHPA) of membrane dilation were significantly higher in individuals from the IS, compared to the individuals from the RS. In addition, there were significant correlations between biometric variables (wet weight, diameter of carapace, gonadal weight, and gonadosomatic index) and the elements Cd, Cu, Ni, and Mn concentrations. Lastly, a delay in the gametogenic cycle of the sea urchins from IS was also observed. Taken together, these findings suggest that direct exposure to trace metals induces histopathological lesions in P. lividus' gonads and affects its reproductive cycle.

Gene expression and functional analysis of different heat shock protein (HSPs) in Ruditapes philippinarum under BaP stress

Heat shock proteins (HSPs) are a class of highly conserved proteins which can protect cells against various types of stress. However, little information on the mechanism involved in the organic contaminants stress response of HSPs is available, especially in marine invertebrates. The present study was conducted to evaluate the responses of HSPs in clams (Ruditapes philippinarum) under Benzo[a] pyrene (BaP) exposure. The clams were exposed to BaP (concentrations: 0, 0.1, 1, 10 μg/L) for 15 days. 6 HSPs mRNA were classified, and the results of tissue distribution indicated that 4 HSPs gene expressed most in the digestive glands. The transcription level of 6 HSPs (HSP22-1, HSP22-2, HSP40A, HSP60, HSP70, HSP90) genes and the aryl hydrocarbon receptor signaling pathway-related genes, and detoxification system-related enzymes activities were analyzed at 0, 1, 3, 6, 10 and 15 days. The activities of phase II detoxification metabolic enzymes and signaling pathway related genes in clams were severely affected by BaP stress and presented significant difference. Our result suggested that HSPs were produced in the presence of BaP and participated in the process of detoxification metabolism to a certain extent. Additionally, the transcription of HSP40A gene may be used as a potential biomarker of BaP exposure due to its evident concentration- and time-dependent expression pattern. Overall, the study investigated the classification of HSPs in R. philippinarum, provided information about the expression profiles of various HSPs after BaP exposure and broadened the understanding mechanism of HSPs in detoxification defense system under PAHs stress in mollusks.

PAHs and PCBs Affect Functionally Intercorrelated Genes in the Sea Urchin Paracentrotus lividus Embryos

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) represent the most common pollutants in the marine sediments. Previous investigations demonstrated short-term sublethal effects of sediments polluted with both contaminants on the sea urchin Paracentrotus lividus after 2 months of exposure in mesocosms. In particular, morphological malformations observed in P. lividus embryos deriving from adults exposed to PAHs and PCBs were explained at molecular levels by de novo transcriptome assembly and real-time qPCR, leading to the identification of several differentially expressed genes involved in key physiological processes. Here, we extensively explored the genes involved in the response of the sea urchin P. lividus to PAHs and PCBs. Firstly, 25 new genes were identified and interactomic analysis revealed that they were functionally connected among them and to several genes previously defined as molecular targets of response to the two pollutants under analysis. The expression levels of these 25 genes were followed by Real Time qPCR, showing that almost all genes analyzed were affected by PAHs and PCBs. These findings represent an important further step in defining the impacts of slight concentrations of such contaminants on sea urchins and, more in general, on marine biota, increasing our knowledge of molecular targets involved in responses to environmental stressors.

De novo Assembly and Analysis of Tissue-Specific Transcriptomes of the Edible Red Sea Urchin Loxechinus albus Using RNA-Seq

Simple Summary

Edible red sea urchin (Loxechinus albus) is an endemic species of echinoderm distributed along the Chilean coasts. This resource has been overexploited in recent years, depleting their natural populations. At present, there are few reported gene sequences available in public databases, restricting the molecular studies associated with aquaculture for this species. The aim of this study was to present the first annotated reference transcriptome of L. albus using NGS technologies and the differential expression transcripts analysis of the evaluated tissues. The transcriptome data obtained in this study will serve as a reference for future molecular research in the edible red sea urchin and other sea urchin species.

Abstract

Edible red sea urchin (Loxechinus albus) is an endemic echinoderm species of the Chilean coasts. The worldwide demand for high-quality gonads of this species has addressed the depletion of its natural populations. Studies on this sea urchin are limited, and genomic information is almost nonexistent. Hence, generate a transcriptome is crucial information that will considerably enrich molecular data and promote future findings for the L. albus aquaculture. Here, we obtained transcriptomic data of the edible red sea urchin by Illumina platform. Total RNA was extracted from gonads, intestines, and coelomocytes of juvenile urchins, and samples were sequenced using MiSeq Illumina technology. A total of 91,119,300 paired-end reads were de novo assembled, 185,239 transcripts produced, and a reference transcriptome created with 38.8% GC content and an N50 of 1769 bp. Gene ontology analysis revealed notable differences in the expression profiles between gonads, intestines, and coelomocytes, allowing the detection of transcripts associated with specific biological processes and KEGG pathways. These data were validated using 12 candidate transcripts by real-time qPCR. This dataset will provide a valuable molecular resource for L. albus and other species of sea urchins.

Microplastic intake and enzymatic responses in Mytilus galloprovincialis reared at the vicinities of an aquaculture station

Aquaculture is a potential source of microplastics (MPs) that could be strong stressors for marine organisms. In this study, we evaluated the effects of MPs derived from aquaculture in antioxidant defences and oxidative stress markers in gills of Mytilus galloprovincialis. Mussels were distributed in three areas with different impacts: inside aquaculture cages, Control 1 (located inside Andratx harbour) and Control 2 (located in a no-anthropized area). Samples were obtained along three different time periods in May (T₀), July (T₆₀) and in September (T₁₂₀). At each sampling period, mussels' biometric measurements were taken, and tissue samples were kept frozen for biochemical determinations and to determine the intake of MPs. An increase in MPs intake was detected throughout the study, and this increase was significantly higher in samples from the aquaculture cages. Similarly, antioxidant enzyme activities (catalase, superoxide dismutase, glutathione reductase and glutathione peroxidase) were significantly higher in samples from cages at T₁₂₀. Additionally, a similar tendency was observed in glutathione-s-transferase, with a higher activity in the aquaculture cages at T₆₀ and T₁₂₀. Malondialdehyde and carbonyl protein derivates as a marker of oxidative damage were also measured and samples from aquaculture cages presented higher oxidative stress markers, mainly in T₁₂₀. In conclusion, living in environments exposed to aquaculture activities at sea may imply a higher intake of MPs which in turn might cause an antioxidant response in M. galloprovincialis which is not enough to avoid oxidative damage.

Long-term exposure to virgin and seawater exposed microplastic enriched-diet causes liver oxidative stress and inflammation in gilthead seabream Sparus aurata, Linnaeus 1758

Plastics accumulation in marine ecosystems has notable ecological implications due to their long persistence, potential ecotoxicity, and ability to adsorb other pollutants or act as vectors of pathogens. The present work aimed to evaluate the physiological response of the gilthead seabream (Sparus aurata) fed for 90 days with a diet enriched with virgin and seawater exposed low-density polyethylene microplastics (LDPE-MPs) (size between 100 and 500 μM), followed by 30 days of depuration, applying oxidative stress and inflammatory markers in liver homogenates. No effects of LDPE-MPs treatments on fish growth were observed throughout this study. A progressive increase in antioxidant enzyme activities was observed throughout the study in both treatments, although this increase was higher in the group treated with seawater exposed MPs. This increase was significantly higher in catalase (CAT), glutathione reductase (GRd), and glutathione-s-transferase (GST) in the seawater exposed MPs group, with respect to the virgin group. In contrast, no significant differences were recorded in superoxide dismutase (SOD) and glutathione peroxidase (GPx) between both groups. Exposure to MPs also caused an increase in the oxidative damage markers (malondialdehyde and carbonyls groups). Myeloperoxidase activity significantly increased because of MPs treatments. After 30 days of depuration, antioxidant, inflammatory enzyme activities and oxidative damage markers returned to values similar to those observed in the control group. In conclusion, MPs exposure induced an increase of antioxidant defences in the liver of S. aurata. However, these elevated antioxidant capabilities were not enough to prevent oxidative damage in the liver since, an increased oxidative damage marker was associated with MPs ingestion. The treatment with seawater exposed MPs caused a more significant antioxidant response (CAT, GRs, and GST). Although after a depuration period of 30 days a tendency to recover the initial values of the biomarkers was observed this does not seem to be time enough for a complete normalization.

Meeting the Salinity Requirements of the Bivalve Mollusc Crassostrea gigas in the Depuration Process and Posterior Shelf-Life Period to Improve Food Safety and Product Quality

Microbiological contamination of bivalve molluscs is one of the major concerns inherent to food safety, thus depuration is frequently needed to assure food safety levels associated with their consumption. Salinity plays an important role in the metabolic activity of bivalves and as such can influence their depuration capacity. This study aimed to evaluate the effect of salinity (25, 30, 35 and 40) on the efficiency of the depuration process, along with the quality and shelf-life of Crassostrea gigas. For this, a 24-h depuration was carried out, followed by a storage period at 5 ± 1 °C for six days. Microbiological analyses and biochemical parameters related to oxidative stress response were analysed. Escherichia coli load was reduced in only 24 h, disregarding the salinity of the system. After the shelf-life period, the activity of the antioxidant defences at salinities 35 and 40 is higher but is still not sufficient to avoid lipid peroxidation. Over time, there is a decrease in oyster metabolism probably due to being chilled and to the action of exposure to air. In sum, this study suggests salinities between 25 and 30 as preferential for the depuration process of C. gigas and subsequent quality during shelf-life.

Cholinesterase characterization and effects of the environmental contaminants chlorpyrifos and carbofuran on two species of marine crabs, Carcinus maenas and Pachygrapsus marmoratus

Among the most frequent targets for toxic effects of modern pesticides, namely organophosphates and carbamates, one may find cholinesterases (ChEs). ChEs exist in a wide variety of animals and have been used actively to discriminate among the environmental effects of different pollutant groups, including the aforementioned pesticides. This study had three purposes, namely (i) identifying the ChE forms present in tissues (eyes and walking legs muscle) of two crab species, Carcinus maenas and Pachygrapsus marmoratus; to (ii) determine the in vitro toxicological effects, and (iii) compare the sensitivity of such enzymatic forms towards commonly used anti-ChE pesticides, namely the organophosphate chlorpyrifos and the carbamate carbofuran. Our results showed that there was not a clear preference for any of the tested substrates in any of the tissues from both species. Furthermore, the ChE activity was almost completely suppressed following incubation with eserine and with the specific inhibitor BW284C51 in all tissues from both species. In vitro exposure to chlorpyrifos promoted a significant decrease in ChE activity in both species. Furthermore, the ChE activity was completely suppressed following incubation with carbofuran and chlorpyrifos. These results suggest that the major ChE forms present in tissues of both crab species show intermediate structural properties and activity patterns, halfway between classic acetylcholinesterase and pseudocholinesterases. However, the sensitivity of the found forms towards ChE inhibitors was established, and the responsiveness of such forms towards common anti-ChE chemicals was established. Both tested species seem to be promising test organisms to be used in marine and coastal scenarios of putative contaminations by anti-ChE chemicals, considering the here reported patterns of response.

Preliminary evidence for an influence of exposure to polycyclic aromatic hydrocarbons on the composition of the gut microbiota and neurodevelopment in three-year-old healthy children

Background

During the second and third year after birth the gut microbiota (GM) is subjected to important development. The polycyclic aromatic hydrocarbon (PAH) exposure could influence the GM in animal and early postnatal exposure is associated with neurodevelopment disorder in children. This study was designed to explore the possible influence of the polycyclic aromatic hydrocarbons (PAHs) on the composition of the gut microbiota (GM) and neurodevelopment in a sample of 38 healthy children at the age of 3 years.

Methods

A brief development (Gesell Development Inventory, GDI) and behavior test (Child Behavior Checklist, CBCL) were completed on 3-yr-olds and stool samples were collected for 16S rRNA V4-V5 sequencing. The PAH-DNA adduct in the umbilical cord blood and the urinary hydroxyl PAHs (OH-PAHs) at the age of 12 months were measured as pre- and postnatal PAH exposure, respectively.

Results

The most abundant two phyla were Bacteroidetes (68.6%) and Firmicutes (24.2%). The phyla Firmicutes, Actinobacteria, Proteobacteria, Tenericutes, and Lentisphaerae were positively correlated with most domain behaviors of the GDI, whereas the Bacteroidetes, Cyanobacteria, and Fusobacteria were negatively correlated. Correspondingly, the phyla Bacteroidetes, Actinobacteria, and Fusobacteria showed positive correlations with most CBCL core and broadband syndromes, whereas the Firmicutes, Verrucomicrobia, Synergistetes, Proteobacteria and Tenericules were negatively correlated. The OH-PAH levels were not significantly associated with the Firmicutes phylum whereas the Bacteroidetes, Bacteroidia, and Bacteroidales all showed significant negative association with the OH-PAH levels.

Conclusion

The current findings suggest that composition of the GM is associated with neurodevelopment of the child. PAHs seem to change the relative abundance of some taxa (some deleted and some recruited) to counteract the negative effects of the PAHs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02539-w.

Experimental evidence of physiological and behavioral effects of microplastic ingestion in Sparus aurata

Increasing global research has identified microplastics (MPs) to be impacting marine organisms. The present work aimed at investigating the physiological and behavioral effects of thirty-six juvenile Sparus aurata exposed to control, virgin and weathered MPs enriched diets during a 21-day period under controlled conditions. Physiological effects were assessed in liver and brain using the following biomarkers: activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRd), the detoxifying enzyme glutathione S-transferase (GST) and malondialdehyde (MDA) as indicative of lipid peroxidation. Individuals were recorded for behavior analysis (i.e. social interactions and feeding behavior). Results revealed an increase in cellular stress from control to weathered fish groups, with the virgin group showing intermediate levels in all quantified biomarkers. Significant differences were found in the liver for all biomarkers except for MDA, suggesting that exposure time to MPs in this experiment is long enough to trigger the activation of antioxidant enzymes but not to produce cell damage by lipid peroxidation. In brain tissue samples, fish from the weathered group presented significantly higher values for CAT and SOD, highlighting its function as primary antioxidants. Regarding behavioral effects, results showed that the two MPs enriched groups were significantly bolder during social interactions and, although no significantly, tended to be more active during feeding. In conclusion, MPs which have been weathered in marine environmental conditions produces a higher physiological response than virgin MPs but also, a physiological response is variable depending on the tissue analyzed. In addition, a short period to MP exposure seems to affect overall social and feeding behavior but, further research is needed to assess long-term effects of MP ingestion and its potential consequences on fish populations.

Sex-Specific Differences in the Toxic Effects of Heavy Fuel Oil on Sea Urchin (Strongylocentrotus intermedius)

The purpose of this study was to explore and compare the sex-specific differences in the toxic effects of water-accommodated fractions of 380# heavy fuel oil (HFO WAF) on the sea urchin Strongylocentrotus intermedius. Sea urchins were acutely exposed to HFO WAF at different nominal concentrations (0%, 10% and 20%) for seven days. The results showed that females had a higher polycyclic aromatic hydrocarbons (PAHs) bioaccumulation in gonad tissues and that both the total antioxidant capacity (TAC) and lipid peroxidation (LPO) levels in the gonad tissues of females were much higher than those of males. The PAHs bioaccumulation in gametes indicated that parents’ exposure could lead to a transfer of PAHs to their offspring, and eggs had higher TAC and LPO than sperms. After maternal and paternal exposure to HFO WAF, the frequency of morphological abnormalities of the offspring was increased when compared to the control. Overall, these results indicated that maternal exposure to HFO WAF could cause more significantly toxic effects on sea urchins than paternal exposure could, which could lead to more significantly negative effects on their offspring.

Flavonoid Glycosides with a Triazole Moiety for Marine Antifouling Applications: Synthesis and Biological Activity Evaluation

Over the last decades, antifouling coatings containing biocidal compounds as active ingredients were used to prevent biofouling, and eco-friendly alternatives are needed. Previous research from our group showed that polymethoxylated chalcones and glycosylated flavones obtained by synthesis displayed antifouling activity with low toxicity. In this work, ten new polymethoxylated flavones and chalcones were synthesized for the first time, including eight with a triazole moiety. Eight known flavones and chalcones were also synthesized and tested in order to construct a quantitative structure-activity relationship (QSAR) model for these compounds. Three different antifouling profiles were found: three compounds (1b, 11a and 11b) exhibited anti-settlement activity against a macrofouling species (Mytilus galloprovincialis), two compounds (6a and 6b) exhibited inhibitory activity against the biofilm-forming marine bacteria Roseobacter litoralis and one compound (7b) exhibited activity against both mussel larvae and microalgae Navicula sp. Hydrogen bonding acceptor ability of the molecule was the most significant descriptor contributing positively to the mussel larvae anti-settlement activity and, in fact, the triazolyl glycosylated chalcone 7b was the most potent compound against this species. The most promising compounds were not toxic to Artemia salina, highlighting the importance of pursuing the development of new synthetic antifouling agents as an ecofriendly and sustainable alternative for the marine industry.

Antioxidant response of the sea urchin Paracentrotus lividus to pollution and the invasive algae Lophocladia lallemandii

Pollution derived from human activities and the arrival of invasive species are common worldwide and affect coastal marine ecosystems negatively, and more especially in a semi-closed sea such as the Mediterranean Sea. The aim of the study was to evaluate oxidative stress biomarkers in the gonadal tissue of the sea urchin Paracentrotus lividus (Lamarck, 1816) sampled in different areas of Sant Antoni de Portmany (Ibiza Island, Spain) with different anthropic activities, and in an area deeply covered by the invasive red algae Lophocladia lallemandii. The densities of P. lividus were higher in the area with the greatest anthropogenic influence, while the area invaded by L. lallemandii showed the lowest density. A significant increase in the activities of the antioxidant enzymes catalase, superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GRd) and the phase II detoxifying enzyme glutathione S-transferase (GST) was found in the most impacted area by the human activity. Moreover, malondialdehyde (MDA) and nitrite levels were also increased in the most impacted area. Similarly, the presence of L. lallemandii induced oxidative stress in P. lividus evidenced by a significant increase in all analysed biomarkers. In conclusion, changes in oxidative stress biomarkers are a good proxy to evaluate the impacts induced by anthropogenic activities and by the presence of invasive algae to P. lividus.

Glutathione S-transferase (GST) genes from marine copepods Acartia tonsa: cDNA cloning and mRNA expression in response to 1,2-dimethylnaphthalene

The calanoid copepod, Acartia tonsa, is relatively sensitive to marine pollution. Glutathione S-transferase (GST) multifunctional enzyme, as a biomarker, play an important role in detoxification metabolism of exogenous substances. In the present study, GST-theta and GST-mu class homology genes (designated as AtGSTT1 and AtGSTM2) were identified and characterized from A. tonsa. The coding sequence of AtGSTT1 comprised 726 bp and encoded a putative protein of 241 amino acid residues. AtGSTM2 contained an open reading frame of 678 bp that encoded a putative 227 amino acid polypeptide. Both proteins contained a conserved GST-N domain and a GST-C domain. Structural analysis revealed the characteristic N-terminal G-site. Three-dimensional structure analysis showed that AtGSTT1 and AtGSTM2 have two typical domains of GST family: The βαβαββα topology structure at the N- terminus and the superhelical structure at the C- terminus. Subsequently, the expression levels of the two GST genes were detected in A. tonsa using real-time quantitative PCR after exposure to 1,2-dimethylnaphthalene (C2-NAPH) at different concentrations (0.574, 5.736 and 57.358 μg/L) for 24, 48, 72, and 96 h. AtGSTT1 mRNA expression was significantly up-regulated in a time-dependent manner and the highest mRNA expression occurred at 5.736 μg/L C2-NAPH exposure for 96 h. AtGSTM2 mRNA expression peaked at 72 h in 0.574 μg/L and 5.736 μg/L dose groups. The expression level of AtGSTM2 showed an increasing trend in a time-dependent manner at 57.358 μg/L of C2-NAPH. These results suggested that GST genes may play an important role in protecting A. tonsa from C2-NAPH pollution, and provide a theoretical basis for further study on the molecular mechanism of polycyclic aromatic hydrocarbon (PAHs) pollution on zooplankton.

PET microplastics toxicity on marine key species is influenced by pH, particle size and food variations

This study aims to evaluate effects induced by the exposure of key marine species to leachates and suspensions of different particle-size of PET microparticles, a plastic polymer that is actually considered safe for the environment. Leachates and suspensions of small (5-60 μm); medium (61-499 μm) and large (500-3000 μm) PET were tested on bacteria (V. fischeri; UNI EN ISO 11348-3:2009), algae (P. tricornutum; UNI EN ISO 10253:2016E), and echinoderms (P. lividus; EPA 600/R-95-136/Section 15) species both under standard (8.0) and acidified (7.5) pH conditions. Results obtained show that: i) conversely to larval stage of P. lividus, bacterial and algal tested species are not sensitive to PET pollution under all tested conditions; ii) different tested particle-sizes of PET produce effects that are not always related to their particle-size; iii) differences comparing acidified and standard pH conditions were recorded; iv) concerning echinoderms, food availability produce significant differences compared to fasting conditions; v) special attention on the possible interactions between MPs and other stressors (e.g., food and pH) is needed in order to give a better picture of natural occurring dynamics on marine ecosystems especially in the future frame of global changes.

Current issues confounding the rapid toxicological assessment of oil spills

Oil spills of varying magnitude occur every year, each presenting a unique challenge to the local ecosystem. The complex, changeable nature of oil makes standardised risk assessment difficult. Our review of the state of science regarding oil's unique complexity; biological impact of oil spills and use of rapid assessment tools, including commercial toxicity kits and bioassays, allows us to explore the current issues preventing effective, rapid risk assessment of oils. We found that despite the advantages to monitoring programmes of using well validated standardised tests, which investigate impacts across trophic levels at environmentally relevant concentrations, only a small percentage of the available tests are specialised for use within the marine environment, or validated for the assessment of crude oil toxicity. We discuss the use of rapid tests at low trophic levels in addition to relevant sublethal toxicity assays to allow the characterisation of oil, dispersant and oil and dispersant mixture toxicity. We identify novel, passive dosing techniques as a practical and reproducible means of improving the accuracy and maintenance of nominal concentrations. Future work should explore the possibility of linking this tiered testing system with ecosystem models to allow the prediction and risk assessment of the entire ecosystem.

The Impact of Chronic Heat Stress on the Growth, Survival, Feeding, and Differential Gene Expression in the Sea Urchin Strongylocentrotus intermedius

To explore the impact of chronic heat stress on commercial echinoderms, the present study assessed the effects of chronic high temperature on the growth, survival, feeding, and differential gene expression in the sea urchin Strongylocentrotus intermedius cultured in northern Yellow Sea in China. One suitable seawater condition (20°C) and one laboratory-controlled high temperature condition (25°C) were set up. After 28 days incubation, our results showed that: (1) The specific growth, survival, and ingestion rates of S. intermedius reared under high temperature (25°C) decreased compared to those reared under optimal temperature (20°C) conditions; (2) comparative transcriptome analysis identified 2,125 differentially expressed genes (DEGs) in S. intermedius reared under high temperature (25°C) compared to those subjected to optimal temperature condition (20°C), which included 1,015 upregulated and 1,100 downregulated genes. The accuracy of the transcriptome profiles was verified by quantitative real-time PCR (qRT-PCR). Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analyses revealed that these DEGs mainly enriched the functional categories of ribosome, protein processing in endoplasmic reticulum, and prion diseases. A total of 732 temperature-induced expressed genes, such as ATP5, heat shock protein 70, and heat shock protein 90, were identified as candidates that were closely correlated with heat resistance in S. intermedius. Differentially expressed transcription factors (TFs), such as AP-1, Fos, CREB, and ZNF, were also identified as potential regulators that regulate the molecular network that was associated with responses to heat stress in sea urchins. Observations in the present study provide additional information that improves our understanding of the molecular mechanism of temperate echinoid species in response to heat stress, as well as theoretical basis for the molecular-assisted breeding of heat-resistant sea urchins.

Inihibition of mullet (M. liza) brain acetylcholinesterase activity by in vitro polycyclic aromatic hydrocarbon exposure

Polycyclic aromatic hydrocarbons (PAH) have been reported as acetylcholinesterase (AChE) inibitors, although in vitro studies on PAH effects on AChE activity are scarce and have only been performed using electric eel brain extracts. Thus, this study investigated PAH effects on brain AChE activity in a tropical fish species in Southeastern Brazil, mullet (Mugil liza). Mullet specimens were obtained from Guanabara Bay (N = 20), Rio de Janeiro, Brazil. Brain AChE was extracted and exposed to an environmentally relevant concentration of Pyrene, Chrysene, Phenanthrene, and Naphthalene, and PAH metabolites, 2-Naphthol and 1-OH-Pyrene. AChE activity inhibition was observed, although no difference was observed between high- and low- molecular weight PAH. 2-Naphthol was a less potent AChE inhibitor than Naphthalene, albeit non-significantly. Further studies are required, since only one PAH concentration was used herein. Mullet brain extracts seem to be adequate to assess possible neurotoxic PAH effects on fish AChE.

Evidences of metabolic alterations and cellular damage in mussels after short pulses of Ti contamination

Mytilus galloprovincialis mussels were exposed to seawater contaminated with Ti. Initial concentrations were 4.1, 32, and 66 μg L^-1 that declined during the first 24 h of the experiments, and after 48 h values were <2 μg L^-1. Experiments were run in triplicate, under constant salinity and temperature. Mussels were fed every two days, and water renewed every seven days and Ti concentrations re-stabilized. During the first 28 days of experimental period, mussels were exposed to four short pulses of contamination, followed by few days of low Ti concentration between weekly contamination renewals. Then mussels were exposed to additional 14-day exposure to Ti uncontaminated seawater. Only residual Ti concentrations were measured in mussels' whole soft tissue after the four pulses of Ti contamination, indicating low Ti accumulation by the organisms. Nevertheless, the biomarkers related to mussels' metabolic capacity (electron transport system activity, ETS), oxidative damage (lipid peroxidation, LPO and reduced glutathione content, GSH), and defense mechanisms (antioxidant and biotransformation enzymes) evidenced the impact of Ti during the 28 days of experimental period. The biomarkers that better indicated the recovery of mussels' biochemical performance were the ETS, LPO, GSH, and the antioxidant enzyme glutathione peroxidase (GPx). LPO was the prime indicator among the analyzed biochemical responses. Organisms appear to hold coping mechanisms to lower the damage induced by Ti, and to recover, albeit the 14 days period of exposure to uncontaminated seawater following the four Ti pulses were not enough for full recovery, as evidenced by results on LPO levels and GSH concentrations. Despite the low solubility of Ti in seawater, the toxicity of this element to a model marine organism was demonstrated.

Parental exposure to heavy fuel oil induces developmental toxicity in offspring of the sea urchin Strongylocentrotus intermedius

The present study investigated the toxic effects of parental (maternal/paternal) exposure to heavy fuel oil (HFO) on the adult reproductive state, gamete quality and development of the offspring of the sea urchin Strongylocentrotus intermedius. Adult sea urchins were exposed to effluents from HFO-oiled gravel columns for 7 days to simulate an oil-contaminated gravel shore, and then gametes of adult sea urchins were used to produce embryos to determine developmental toxicity. For adult sea urchins, no significant difference in the somatic size and weight was found between the various oil loadings tested, while the gonad weight and gonad index were significantly decreased at higher oil loadings. The spawning ability of adults and fecundity of females significantly decreased. For gametes, no effect was observed on the egg size and fertilization success in any of the groups. However, a significant increase in the percentage of anomalies in the offspring was observed and then quantified by an integrative toxicity index (ITI) at 24 and 48 h post fertilization. The offspring from exposed parents showed higher ITI values with more malformed embryos. The results confirmed that parental exposure to HFO can cause adverse effects on the offspring and consequently affect the recruitment and population maintenance of sea urchins.

Multi-biomarkers approach to the assessment of the southeastern Mediterranean Sea health status: Preliminary study on Stramonita haemastoma used as a bioindicator for metal contamination

The present study aimed to evaluate the responses of different biochemicals parameters associated with environmental pollution in the digestive gland of the gastropod mollusc Stramonita haemastoma. Physiochemical parameters and trace metal elements (Copper (Cu), Zinc (Zn), Chromium (Cr), Cadmium (Cd) and Lead (Pb)) were measured in seawater. Spatiotemporal variations in reduced glutathione (GSH), malondialdehyde (MDA) and metallothionein (Mt) as well as the specific activities of glutathione S-transferase (GST) and catalase (CAT) were evaluated in digestive gland of this species during a one-year period in 2013-2014. Samples collection was conducted at three sites. The results obtained showed seasonal fluctuations in GST and CAT activities and in the rate of Mt content. In addition, intersite variations in GSH, MDA, Mt and CAT were recorded in individuals. Also, trace metal elements concentrations determined by season in the digestive gland revealed spatial and temporal variations for Cu and Zn but they are below the limit of detection for Cd and Pb. The highest values were generally recorded in spring for Cu and in winter for Zn. In this first regional study using in S. haemastoma as a model, the biomarkers measured were seen to be inducible parameters to evaluate the health state of the organism and the overall quality of the study sites.

Seasonal antioxidant responses in the sea urchin Paracentrotus lividus (Lamarck 1816) used as a bioindicator of the environmental contamination in the South-East Mediterranean

In this study, sea urchin Paracentrotus lividus were sampled seasonally at three stations during 2012 in the coastal areas of the Gulf of Annaba (southeast Mediterranean). For all sea urchins, the gonad index was calculated to determine sea urchin reproductive status. Moreover, a set of biochemical parameters, including biomarkers and oxidative stress parameters, was measured in gonads. The pesticides and physiochemical parameters were measured and dosed in sea water. The results obtained highlighted that the levels of pesticide were generally low and below those commonly applied by environmental quality standards (EQS), indicating that no alarm state is currently present in the Gulf of Annaba. In addition to pollution, seasonal change is an important factor influencing biomarker activity, and the significant increases in biomarker levels in spring are a major observed trend. This activity may also be related to reproductive status. Seasonal variability was confirmed by the significant results of the Kruskal-Wallis test and by the high degree of divergence between seasons in PCA, with a total of 83.83% of variance explained. These results indicate that environmental factors that vary seasonally may affect the antioxidant status of the sea urchin Paracentrotus lividus.

Antifouling potential of Nature-inspired sulfated compounds

Natural products with a sulfated scaffold have emerged as antifouling agents with low or nontoxic effects to the environment. In this study 13 sulfated polyphenols were synthesized and tested for antifouling potential using the anti-settlement activity of mussel (Mytilus galloprovincialis) plantigrade post-larvae and bacterial growth inhibition towards four biofilm-forming bacterial strains. Results show that some of these Nature-inspired compounds were bioactive, particularly rutin persulfate (2), 3,6-bis(β-D-glucopyranosyl) xanthone persulfate (6), and gallic acid persulfate (12) against the settlement of plantigrades. The chemical precursors of sulfated compounds 2 and 12 were also tested for anti-settlement activity and it was possible to conclude that bioactivity is associated with sulfation. While compound 12 showed the most promising anti-settlement activity (EC₅₀ = 8.95 μg.mL⁻¹), compound 2 also caused the higher level of growth inhibition in bacteria Vibrio harveyi (EC₂₀ = 12.5 μg.mL⁻¹). All the three bioactive compounds 2, 6, and 12 were also found to be nontoxic to the non target species Artemia salina (<10% mortality at 250 μM) and Vibrio fischeri (LC₅₀ > 1000 μg.mL⁻¹). This study put forward the relevance of synthesizing non-natural sulfated small molecules to generate new nontoxic antifouling agents.

Oxidative status assessment of the endemic bivalve Pinna nobilis affected by the oil spill from the sinking of the Don Pedro

Several biomarkers were determined to evaluate the effects of the Don Pedro spillage on the digestive gland of the fan mussel Pinna nobilis (Linnaeus, 1758). Two areas in the southeast of Ibiza Island (Western Mediterranean) were selected; one affected by the oil spill (Talamanca) and one did not affected (Espardell). Mussels were sampled one, six and twelve months after the accident. PAH levels were elevated in P. nobilis from the affected area one month after the accident and, although they were decreasing gradually, they were always higher than in the control area. An increase in enzyme activities, reduced glutathione and lipid peroxidation were evidenced one month after the spillage, with no changes in acetylcholinesterase. All biomarkers progressively returned to basal levels one year after the oil spill. In conclusion, the Don Pedro oil spill induced an acute situation of oxidative stress on P. nobilis that were recovered twelve months later.

Proteomic profiling of gill GSTs in Mytilus galloprovincialis from the North of Portugal and Galicia evidences variations at protein isoform level with a possible relation with water quality

Glutathione transferases (GSTs) are key for xenobiotic detoxification at the molecular level across phyla. These enzymes are therefore likely to be part of the defence mechanisms used by marine organisms, such as mussels, that thrive in highly polluted environments. Taking this hypothesis into account, we used proteomics to characterize the profile of GSTs from the gills of marine mussel Mytilus galloprovincialis in order to discriminate natural mussel populations exposed to different levels of pollution. Samples were collected between Cabo Home (Spain) and Matosinhos (Portugal) covering a north-south transect of approximately 122 Km of the Atlantic Ocean along the Western Coast of the Iberian Peninsula. GSTs from mussel gills were extracted and purified by affinity chromatography with glutathione as the binding substrate to the solid medium. We studied the abundance of GST isoforms by two-dimensional gel electrophoresis and matrix assisted laser desorption/ionization-time of flight mass spectrometry and assessed total activity. Eleven putative individual GSTs from classes Mu, Pi and Sigma were identified by proteomics. Few variations were observed in total GST activity of post-mitochondrial samples between sampling sites, with animals from Matosinhos (polluted site) showing highest GST activity and Cabo Home (clean site) showing lowest. This contrasts with the increased number of differences in the individual GST isoforms. Each mussel population showed unique GST proteomic profiles. Based on the results we conclude that proteomics surpasses the conventional GST enzymatic activity method to discriminate natural mussel populations and has potential application in environmental monitoring. It is reasonable to suggest that the GST proteomic profiles observed may reflect differences in contamination levels.

Acetylcholinesterase in Biofouling Species: Characterization and Mode of Action of Cyanobacteria-Derived Antifouling Agents

Effective and ecofriendly antifouling (AF) compounds have been arising from naturally produced chemicals. The objective of this study is to use cyanobacteria-derived agents to investigate the role of acetylcholinesterase (AChE) activity as an effect and/or mode of action of promising AF compounds, since AChE inhibitors were found to inhibit invertebrate larval settlement. To pursue this objective, in vitro quantification of AChE activity under the effect of several cyanobacterial strain extracts as potential AF agents was performed along with in vivo AF (anti-settlement) screening tests. Pre-characterization of different cholinesterases (ChEs) forms present in selected tissues of important biofouling species was performed to confirm the predominance of AChE, and an in vitro AF test using pure AChE activity was developed. Eighteen cyanobacteria strains were tested as source of potential AF and AChE inhibitor agents. Results showed effectiveness in selecting promising eco-friendly AF agents, allowing the understanding of the AF biochemical mode of action induced by different compounds. This study also highlights the potential of cyanobacteria as source of AF agents towards invertebrate macrofouling species.

Toxicity of polyunsaturated aldehydes of diatoms to Indo-Pacific bioindicator organism Echinometra mathaei

Although it is well known suitability of early developmental stages of sea urchin as recommended model for pollutant toxicity testing, little is known about the sensitivity of Indo-Pacific species Echinometra mathaei to polyunsaturated aldehydes. In this study, the effect of three short chain aldehydes, 2,4-decadienal (DD), 2,4-octadienal (OD) and 2,4-heptadienal (HD), normally found in many diatoms, such as Skeletonema costatum, Skeletonema marinoi and Thalassiosira rotula, was evaluated on larval development of E. mathaei embryos. Aldehydes affected larval development in a dose-dependent manner, in particular HD>OD>DD; the results of this study highlighted the higher sensitivity of this species toward aldehydes compared with data registered for other sea urchin species. In comparison with studies reported in the literature, contrasting results were observed during our tests; therefore, an increasing toxic effect was registered with decreasing the chain length of aldehydes. This work could provide new insights in the development of new toxicological assays toward most sensitive species.

Sertraline accumulation and effects in the estuarine decapod Carcinus maenas: importance of the history of exposure to chemical stress

Sertraline is widely prescribed worldwide and frequently detected in aquatic systems. There is, however, a remarkable gap of information on its potential impact on estuarine and coastal invertebrates. This study investigated sertraline accumulation and effects in Carcinus maenas. Crabs from a moderately contaminated (Lima) and a low-impacted (Minho) estuary were exposed to environmental and high levels of sertraline (0.05, 5, 500 μg L(-1)). A battery of biomarkers related to sertraline mode of action was employed to assess neurotransmission, energy metabolism, biotransformation and oxidative stress pathways. After a seven-day exposure, sertraline accumulation in crabs' soft tissues was found in Lima (5 μg L(-1): 15.3 ng L(-1) ww; 500 μg L(-1): 1010 ng L(-1) ww) and Minho (500 μg L(-1): 605 ng L(-1) ww) animals. Lima crabs were also more sensitive to sertraline than those from Minho, exhibiting decreased acetylcholinesterase activity, indicative of ventilatory and locomotory dysfunction, inhibition of anti-oxidant enzymes and increased oxidative damage at ≥ 0.05 μg L(-1). The Integrated Biomarker Response (IBR) index indicated their low health status. In addition, Minho crabs showed non-monotonic responses of acetylcholinesterase suggestive of hormesis. The results pointed an influence of the exposure history on differential sensitivity to sertraline and the need to perform evaluations with site-specific ecological receptors to increase relevance of risk estimations when extrapolating from laboratory to field conditions.

Cholinesterase activity in the caddisfly Sericostoma vittatum: Biochemical enzyme characterization and in vitro effects of insecticides and psychiatric drugs

Sericostoma vittatum is a caddisfly species, endemic to the Iberian Peninsula, proposed as a biomonitor species for lotic ecosystems. Since inhibition of cholinesterases׳ (ChE) activity has been used to evaluate the exposure of macroinvertebrates to organophosphates and carbamate pesticides, this work intended to characterize the ChE present in this species so their activity can be used as a potential biomarker of exposure. Biochemical and pharmacological properties of ChE were characterized in this caddisfly species using different substrates (acetylthiocholine iodide, propionylthiocholine iodide, and butyrylthiocholine iodide) and selective inhibitors (eserine sulfate, BW284c51, and iso-OMPA). Also, the in vitro effects of two insecticides (carbaryl and chlorantraniliprole) and two psychiatric drugs (fluoxetine and carbamazepine) on ChE activity were investigated. The results suggest that S. vittatum possess mainly AChE able to hydrolyze both substrates acetylthiocholine and propionylthiocholine since: (1) it hydrolyzes the substrate acetylthiocholine and propionylcholine at similar rates and butyrylthiocholine at a much lower rate; (2) it is highly sensitive to eserine sulfate and BW284c51, but not to iso-OMPA; and (3) its activity is inhibited by excess of substrate, a characteristic of typical AChE. in vitro inhibitions were observed only for carbaryl exposure while exposure to chlorantraniliprole and to relevant environmental concentrations of psychiatric drugs did not cause any significant effect on AChE activity. This study suggests that AChE activity in caddisflies can indeed be used to discriminate the effects of specific insecticides in monitoring programs. The use of non-target species such as caddisflies in ecotoxicological research in lotic ecosystems is also discussed.

Using a multibiomarker approach and behavioural responses to assess the effects of anthracene in Palaemon serratus

Polycyclic aromatic hydrocarbons (PAHs) are recognised as one of the main groups of contaminants that assume more importance in the marine environment, enhancing the need of studies concerning their adverse effects and more efficient and ecologically relevant tools for environmental monitoring purposes. This study aims to apply an integrated approach including several multi-level biological responses (accumulation levels, biochemical responses important for different physiological functions and behavioural alterations) to assess the ecological relevance of the effects induced by sub-lethal concentrations of anthracene (ANT) in Palaemon serratus (common prawn). ANT accumulation was assessed by measuring the levels of ANT-type compounds in prawn digestive gland, muscle and eye; biochemical responses were determined using biomarkers involved in biotransformation, oxidative damage, energy production and neurotransmission processes; and behavioural alterations through swimming performance after 96 h exposure bioassay (ANT:16-1,024 μg/L). The rationale behind this approach is to assess the ecologically relevant effects induced by ANT in prawn, given by the association between behavioural alterations with biochemical responses, in search for more efficient tools for environmental risk assessment. Results show a significant decrease of swimming velocity (LOEC=128 μg/L) along with increased levels of ANT-type compounds in digestive gland (LOEC=128 μg/L), muscle (LOEC=256 μg/L) and eye (LOEC=32 μg/L) in prawn exposed to ANT. Increased activities of glutathione peroxidase (GPx) and catalase (CAT), involved in anti-oxidant defence system, were also observed (LOEC=256 μg/L; 1024μg/L, respectively) in the digestive gland of prawn, induction of oxidative damage in lipids (LPO) also occurred (LOEC=32 μg/L). The inhibition of swimming velocity showed a correlation with some biochemical parameters measured, including the levels of ANT-type compounds in tissues and LPO, and thus these may be considered sensitive and ecologically relevant criteria as well as early warning endpoints for assessing polycyclic aromatic compounds exposure effects on marine organisms.

Cholinesterase activity on Echinogammarus meridionalis (Pinkster) and Atyaephyra desmarestii (Millet): characterisation and in vivo effects of copper and zinc

Metals are released into freshwater ecosystems from natural and anthropogenic sources, compromising their structural and functional equilibrium. As early warning tools, cholinesterases (ChEs) are usually used to assess the effects of organophosphate and carbamate pesticides, but are also known to be inhibited by metals. The objectives of this work were to characterise the activity of ChE present in the amphipod Echinogammarus meridionalis and the shrimp Atyaephyra desmarestii and to evaluate the in vivo effects of the metals copper and zinc in their ChE activity. To achieve this, firstly the activity of ChE forms were characterised using different in vitro assays with substrates and selective inhibitors. Then, the in vivo effects of 48 h exposures to increasing concentrations of copper and zinc on ChE activity were determined. The ChE form present in both species was acetylcholinesterase (AChE) since both revealed preference for the acetylthiocholine iodide substrate, total inhibition with eserine, the inhibitor of ChEs, and with 1,5-bis(4-allyldimethylammoniumphenyl)-pentan-3-one dibromide, the specific inhibitor of AChE, and presented insensitivity to iso-OMPA, a specific inhibitor of butyrylcholinesterase. The activity of ChEs was inhibited by zinc exposures in the amphipod species, but was not affected by copper. Exposure to copper and zinc did not affect ChEs activity in the shrimp at the concentrations tested. This work is a relevant contribution as foundation for the use of AChE in freshwater crustaceans in further studies including biomonitoring campaigns in different contamination scenarios.

Arsenic exposure affects embryo development of sea urchin, Paracentrotus lividus (Lamarck, 1816)

Toxicity tests were performed with embryos of Paracentrotus lividus to investigate the toxicological effect of two arsenic species: arsenate (As(V)), expected to be more toxic, and dimethyl-arsinate (DMA) expected to be less toxic. Exposures to toxicants were performed at different developmental stages in order to identify the most sensitive phase of embryological development. Statistical analysis revealed a high significance of each factor (Molecule, Concentration and Time of exposure) and their interaction for the dependent variable "Percentage of normal-shaped plutei". In particular, the 8 cell stage was the most sensitive to arsenic; at a concentration of 50 μg L(-1) DMA proved to be more toxic than As(V), resulting in nearly 50 % of normal-shaped plutei against the 74 % recorded for As(V). Starting the administration of arsenic at the morula stage, arsenate proved to be significantly more toxic when compared to DMA.

Behaviour and biomarkers as tools to assess the acute toxicity of benzo(a)pyrene in the common prawn Palaemon serratus

Benzo(a)pyrene (BaP) is considered an important marine environmental contaminant, given its recognised environmental persistence and toxicity. However, its effects in marine crustaceans are poorly studied, namely the accumulation and sub-cellular effects that might be linked to behavioural alterations and may lead to ecologically relevant consequences. This study aims to investigate behavioural and physiological responses of the common prawn (Palaemon serratus) after acute exposure to BaP and infer the potential effects for the population in the wild. The applied approach included the evaluation of swimming performance after exposure, and several biochemical biomarkers involved in biotransformation, oxidative damage, energy production and levels of BaP-type compounds in tissues (eye, digestive gland and muscle) in a 96 h acute bioassay with exposure to BaP (16-4096 μg/L). The objective was to establish a link between behaviour (swimming velocity) and biochemical responses in order to assess the ecological relevance of the effects induced by BaP in P. serratus and to select useful tools for environmental risk assessment. Results showed swimming velocity impairment (LOEC = 128 μg/L), lipid peroxidation (LPO) induction (LOEC = 4096 μg/L) and BaP-type compounds increase in eye (LOEC = 32 μg/L), digestive gland and muscle (LOEC = 512 μg/L) of prawn after exposure to BaP. This oxidative damage in lipids seems to be caused by the incapacity to activate detoxification and anti-oxidant enzymes, once glutathione-S-transferase (GST), catalase (CAT) and glutathione peroxidase (GPx) were not affected by the exposure. This could be also an explanation to the increased levels of BaP-type compounds observed in tissues. An inability to increase the activities of enzymes involved in the production of energy was also observed, which may help to explain the detoxification failure and consequent increased levels of lipid peroxidation. The inhibition of swimming velocity was negatively correlated with biochemical parameters, including the presence of BaP-type compounds in different tissues and LPO, and thus, these parameters might be used as ecologically relevant and early-warning tools to assess the effects of PAHs. This study also highlights the usefulness of the fixed wavelength fluorescence (FF) technique to quantify PAHs-type compounds in tissues as indicative of exposure of P. serratus to PAHs, namely the sensitivity of eyes, which might be used for monitoring purposes and in marine ecological risk assessment studies.

Physiological response of the sea urchin Paracentrotus lividus fed with the seagrass Posidonia oceanica and the alien algae Caulerpa racemosa and Lophocladia lallemandii

The aim was to determine the effects of alien algae feeding on biomarkers of oxidative stress in the sea urchin Paracentrotus lividus. Sea urchins were fed during three months with the native seagrass Posidonia oceanica, and the alien macroalgae Caulerpa racemosa and Lophocladia lallemandii and biochemical analysis were performed in the gonads. A control group was immediately processed after sampling from the sea. Antioxidant enzyme and glutathione S-transferase activities and GSH concentration were significantly higher in sea urchins fed with alien algae when compared with the control group and the one fed with P. oceanica group. This response was more intense in the group fed with L. lallemandii respect to the C. racemosa group. The concentration of MDA, protein carbonyl derivates and 8-OHdG reported no significant differences between treatments. In conclusion, the invasive algae C. racemosa and L. lallemandii induced an antioxidant response in P. lividus without evident oxidative damage.

Acetyl cholinesterase activity and muscle contraction in the sea urchin Lytechinus variegatus (Lamarck) following chronic phosphate exposure

The common shallow-water sea urchin Lytechinus variegatus is capable of surviving inorganic phosphate exposures as high as 3.2 mg L(-1) and organic phosphate exposures of 1000 mg L(-1) . Nonetheless, chronic exposure to low, medium, and high-sublethal concentrations of organic phosphate inhibits the muscle enzyme acetyl cholinesterase (AChE), responsible for the break down of the neurotransmitter acetylcholine, as well as inhibiting contractions in the muscles associated with the Aristotle's lantern. AChE activity, measured in both a static enzyme assay and by vesicular staining, displayed concentration-dependent declines of activity in individuals maintained in organic phosphate for 4 weeks. The activity of AChE was not adversely affected by exposure to inorganic phosphate or seawater controls over the same time period. Maximum force of muscle contraction and rates of muscle contraction and relaxation also decreased with chronic exposure to increasing concentrations of organic phosphate. Chronic exposure to inorganic phosphates elicited no response except at the highest concentration, where the maximum force of muscular contraction increased compared to controls. These findings indicate that shallow-water populations of Lytechinus variegatus subjected to organic phosphate pollutants may display impaired muscular activity that is potentially related to the inhibition of the muscle relaxant enzyme AChE, and subsequently muscular overstimulation, and fatigue.

Challenges in assessing the toxic effects of polycyclic aromatic hydrocarbons to marine organisms: a case study on the acute toxicity of pyrene to the European seabass (Dicentrarchus labrax L.)

The acute toxicity (96 h) of pyrene (PY) to European seabass (Dicentrachus labrax) juveniles assessed in a semi-static bioassay (SSB) with medium renewal at each 12h, and in a static bioassay (SB) without medium renewal was compared in laboratorial conditions (water PY concentrations: 0.07-10 mg L(-1)). Main findings in the SSB that assessed mainly the toxicity of PY and its metabolites were: increased levels of bile PY metabolites in good agreement with the profile of lipid peroxidation levels (LPO) in exposed fish relating PY exposure and oxidative damage; increased levels of PY-type compounds in the brain indicating their ability to cross the blood-brain barrier; increased levels of these substances in liver and muscle which are edible tissues for humans thus raising concern on potential adverse effects on consumers of fish from PY contaminated areas; a significant inhibition of glutathione S-transferase activity suggesting its involvement in PY detoxication as toxicant scavenger; finally, an almost complete impairment of the swimming velocity at all the PY concentrations linking sub-individual to higher population level effects. In the SB, where the overall toxicity of PY, its metabolites and environmental degradation products was evaluated, 19% and 79% of PY decay in test media was found at 12 and 96 h, respectively. In general, the effects were similar to those of SSB but with significant effects being induced at higher PY concentrations indicating that the parental compound is more toxic than its environmental degradation products. The other main differences relatively to the SSB were: increased levels of PY-type substances in the liver suggesting more accumulation in this organ. Therefore, these findings highlight the need of carefully considering experimental design options when assessing the toxicity of readily degradable substances to marine fish, and stress the importance of taking into consideration the toxicity of environmental degradation products in addition to toxic effects of the parental substance and its metabolites for marine ecological risk assessment.

Effects of carbofuran on the sea bass (Dicentrarchus labrax L.): study of biomarkers and behaviour alterations

The objective of this study was to investigate the acute effects of the pesticide carbofuran on the sea bass (Dicentrarchus labrax) using parameters at different levels of biological organisation (swimming behaviour and several biomarkers) and possible relationships between alterations found in different effect criteria. In a bioassay, sea bass juveniles were individually exposed to different doses of carbofuran (31, 63, 125 and 250 μg/L) for 96 h. At the end of the bioassay, the swimming performance and 11 biomarkers were determined. Biomarkers were: hepatosomatic index (HSI), lipid peroxidation (LPO), reduced glutathione and the activities of the enzymes ethoxyresorufin O-deethylase (EROD), glutathione S-transferases, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, brain acetylcholinesterase (AChE) and muscle cholinesterases (ChE). After 96 h of exposure, carbofuran induced a decrease of the swimming velocity and inhibition of EROD activity at all concentrations tested, and inhibition of muscle ChE and brain AChE activities at 250 μg/L. No relevant alterations in any of the other tested parameters were found. These results show that carbofuran induced adverse effects on fish by interfering with neurofunction, capability of detoxication and swimming velocity. In addition, positive and significant correlations between the swimming velocity and (i) brain AChE activity, (ii) muscle ChE activity and (iii) EROD activity suggest that the inhibition of these enzymes may somehow be related to the behavioural changes observed. Since these functions are determinant for the survival and performance of the fish in the wild, the findings of the present study suggest that adverse effects may occur in populations exposed to carbofuran if a sufficient number of animals is affected.

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.

AChE and EROD activities in two echinoderms, Holothuria leucospilota and Holoturia atra (Holothuroidea), in a coral reef (Reunion Island, South-western Indian Ocean)

AChE and EROD activities were investigated in two holothurian species, Holothuria leucospilota and Holoturia atra, from a tropical coral reef. These organisms were collected from 3 back-reef stations, where temperature and salinity were homogeneous. The activity levels of both AChE and EROD varied significantly between the two species, but were in the range of values determined in other echinoderm species. AChE activity levels were higher in the longitudinal muscle than in the tentacle tegument. Among the several tissues tested, the digestive tract wall exhibited higher EROD activity levels. Sex did not influence AChE and EROD activity levels in both species. Animal biomass and EROD activity levels were only correlated in the tegument tissue of H. atra, and we hypothesize a possible influence of age. EROD activity did not show intraspecific variability. A significant relationship was found between AChE activity and Cuvierian tubules time of expulsion in Holothuria leucospilota. Individuals collected at the southern site presented both lower AChE activity levels and Cuvierian tubules time of expulsion, indicating possible neural disturbance. More information on holothurians biology and physiology is needed to further assess biomarkers in these key species. This study is the first of its kind performed in the coastal waters of Reunion Island and data obtained represent reference values.

Cholinesterase and glutathione S-transferase activities of three mollusc species from the NW Portuguese coast in relation to the 'Prestige' oil spill

In November 2002, the tanker 'Prestige' released about 19,000 tonnes of a heavy fuel oil (no. 6) before sinking with about 58,000 tonnes of its cargo, 135 miles from Cabo Finisterra (Spain). A considerable part of the released fuel oil reached the Galician coast, causing a heavy black tide and an ecological disaster. Although the black tide did not reach the NW coast of Portugal, it is possible that some of the fuel oil or its components also arrived to this area directly through the sea water and/or indirectly through the food chain. Therefore, the aim of this study was to investigate possible changes in two widely used biomarkers, the activity of the enzymes cholinesterases (ChE) and glutathione S-transferases (GST), of three molluscs (Mytilus galloprovincialis, Nucella lapillus and Monodonta lineata) from wild populations of the NW Portuguese coast in relation to the 'Prestige' oil spill. Molluscs were collected seasonally before (autumn 2002) and after (winter 2002/2003), spring and summer 2003) the oil spill at several sites along the Portuguese NW coast. Enzymatic activities determined before the accident were compared with those determined at different times after the oil spill taking into consideration abiotic factors. Information from different parameters was integrated by Redundancy Analysis and Principal Response Curves (PRC). Results show that GST and ChE activities were influenced by abiotic factors. Despite this influence, the results of PRC analysis also suggest that some of the fuel oil reached the NW Portuguese coast changing the patterns of ChE and GST activities of local populations of rocky shore species. Furthermore, the present study highlights the need of long-term monitoring with wild populations to assess both historical and punctual effects of pollution in the marine environment.

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.

Vitellogenin gene expression in the intertidal blenny Lipophrys pholis: a new sentinel species for estrogenic chemical pollution monitoring in the European Atlantic coast?

The presence of estrogenic chemicals (ECs) in the aquatic environment is a growing problem. While most attention was initially given to fresh water and estuarine ecosystems, it is now evident that coastal marine areas are also vulnerable to these pollutants. The use of vitellogenin induction in male fish, a specific biomarker of EC exposure, has been the most widely applied methodology. However, in some occasions, the high mobility and migratory behaviour of common sentinel fish species makes data interpretation difficult. Hence, there is the need to validate new sentinel marine fish species which should display, among other features, a strong homing behaviour. The shanny, Lipophrys pholis, is an intertidal fish that combines many of the required characteristics for a sentinel species: abundance and easy of catch, wide geographical distribution and restricted home range. Thus, in order to evaluate, in the field, the species sensitivity to ECs, L. pholis males were collected at two sites reflecting different degrees of anthropogenic contamination. The vitellogenin II gene (VTGII) was isolated and its liver expression evaluated by RT-PCR in the field samples. A significant induction of gene expression was observed in the specimens collected in the urban area, if compared to the reference site, which suggests exposure to ECs. Moreover, a 21-days laboratory exposure to environmental relevant concentrations of ethinylestradiol (EE2) was also performed. A significant induction of L. pholis VTGII gene in EE2 exposed males was observed suggesting similar sensitivity to that of other marine/estuarine fishes. Even though further validation is currently in progress, the available data indicates that L. pholis is responsive to ECs, thus favouring its future integration in monitoring programmes designed to evaluate the presence of ECs in European marine ecosystems.

Effect of long-term exposure to simazine on brain and muscle acetylcholinesterase activity of common carp (Cyprinus carpio)

Several water-contamination incidents with simazine have occurred in the province of Badajoz (Spain), due to its excessive use for controlling weeds in olive trees and vineyards. Simazine residues were also detected in drinking water, increasing public health concern. However, little is known on the effects that low levels of simazine pose to environment organisms. We investigated if residues of simazine in the natural waters would affect brain and muscle acetylcholinesterase activity in common carps captured in areas in which simazine residues were detected at average levels of 4.5 microg/L. Results confirmed depression on brain and muscle acetylcholinesterase activity of 20% and 29%, respectively, in carps inhabiting one of the simazine-contaminated ponds, termed "Molinos de Matachel." To assess the biological significance of this finding, we developed a controlled laboratory study in which carps were exposed to simazine at 45 microg/L (10-fold that of the natural water levels) for 90 days. The results obtained in the field study were not confirmed in our laboratory experiment, since carps did not show evidence or brain or muscle acetylcholinesterase activity depression for the duration of the experiment, and therefore, we can conclude that acetylcholinesterase depression found in carps collected in "Molinos de Matachel" should be ascribed to other compounds or mixtures of xenobiotics.

Hepatic monooxygenase (CYP1A and CYP3A) and UDPGT enzymatic activities as biomarkers for long-term carbofuran exposure in tench (Tinca tinca L)

The effect of a long-term exposure of tenchs to different concentrations (10 and 100 micro g/L) of the pesticide carbofuran has been evaluated. Microsomal hepatic cytochrome P450 subfamily 1A (CYP1A) and 3A (CYP3A) activities, as well as the phase II enzyme uridine diphospho-glucuronosyltransferase (UDPGT) activity were evaluated as adequate biomarkers of fish exposure to environmentally relevant concentrations of the pesticide carbofuran in freshwater ecosystems. A clear time-dependent inhibition of both CYP1A and UDPGT activities was observed in fish exposed to the highest dose of carbofuran with respect to controls, whereas in the case of CYP3A activity, values of exposed animals did not show a clear pattern of alteration during the experiment. The results of the present study demonstrated that hepatic CYP1A and UDPGT activities from tench could be considered as sensitive biomarkers for carbamate pesticides in polluted water, thus allowing future and ecologically relevant biomonitoring studies with this species.

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.

Cholinesterase activities in the scallop Pecten jacobaeus: characterization and effects of exposure to aquatic contaminants

Nearshore marine environments of industrialized countries are increasingly threatened by anthropogenic pollution. It is therefore a priority task to investigate the sensitivity of new ecotoxicological warning signals of the occurrence and effects of aquatic pollutants. The main aims of the present study were: 1) to characterize the biochemical properties of ChEs in tissues of the bivalve Pecten jacobaeus, using different specific substrates and selective inhibitors; 2) to measure sensitivity of ChE activities to in vitro exposure to the OPs azamethiphos and DFP and to the heavy metals cadmium and zinc. Our final aim was to carry out a preliminary evaluation of the suitability of ChEs measurement in tissues of the scallop for monitoring marine environmental quality and neurotoxic compounds contamination in the Mediterranean Sea. Responses to specific inhibitors have suggested that ChEs in adductor muscle share many characteristics with vertebrate acetylcholinesterase. Dose-dependent inhibition of ChE was observed in response to in vitro exposure to environmental contaminants such as cadmium and azamethiphos. Sensitivity to zinc and DFP was lower. ChEs in P. jacobaeus might therefore have potential as a sensitive biomarker for monitoring marine pollution. Results of the present study will be useful to focus further experiment of exposure to pollutants under in vivo conditions.

CAPSULE

Cholinesterase activities in scallop Pecten jacobaeus were observed to be sensitive to contaminants in vitro and may therefore have potential as biomarkers for monitoring water pollution.