Monitoring pollution in Tunisian coasts: application of a classification scale based on biochemical markers

Investigating seasonal metal impact on Stramonita haemastoma gastropod along the Algerian East Coast: Understanding through various pollution indicators

The main objective of this study was to assess the impact of environmental pollution on the gastropod Stramonita haemastoma by examining various physiological and biochemical parameters. Trace metal elements (TME) were measured in the snail's foot. Over a one-year period from 2013 to 2014, the study investigated the variations in reduced glutathione, malondialdehyde, metallothionein, glutathione S-transferase, acetylcholinesterase and catalase activities in the foot of the gastropod at three different sites. The results showed spatiotemporal fluctuations in biomarkers, physiological parameters and TME. This integrative approach, being the first of its kind in the region using S. haemastoma as a model organism, represents a means of environmental assessment accessible to all countries allowing the monitoring and conservation of coastal marine environments on a national and international scale and which could be used in marine biomonitoring programs to indicate the impact of pollution and assess the quality of the Algerian coastal marine environment.

Study on the toxic effects of sodium pentachlorophenol (PCP-Na) on razor clam (Sinonovacula constricta)

Currently, research on toxic effects of PCP Na is greatly insufficient. The aim of this study is to explore the toxic effects of PCP-Na for better conducting future work on PCP-Na toxicology. For this purpose, S. constricta adults were exposed to PCP-Na for toxicity testing. The results showed that PCP-Na could easily bioaccumulate in S. constricta and significantly affected both phrase I and II metabolism enzymes. Meanwhile, PCP-Na strongly activated antioxidant system and caused PC, LPO and DNA damage. In addition, neurotoxicity and immunotoxicity of PCP-Na was demonstrated in this study. Interestingly, we observed that PCP-Na significantly affected the expression of genes of electron transport chain and induced key enzymes of glycolysis, indicating that PCP-Na may act as an uncoupler of oxidative phosphorylation, interfering with energy supply and causing energy compensation. This study is the first to fully analyze and provide a new perspective on the toxicity of PCP-Na.

Metabolomic disorders unveil hepatotoxicity of environmental microplastics in wild fish Serranus scriba (Linnaeus 1758)

Coastal areas are worldwide subject to large inputs of anthropogenic wastes that are discharged directly into inshore waters, where they will be weathered into small microplastics (MPs) of up to a size <20 μm. This study provides information about the presence of small environmental MPs (≤3 μm) in the liver of adult benthopelagic fish Serranus scriba (Linnaeus 1758), caught from three coastal regions in Tunisia distinguished by different patterns of human activity. Polymer composition in fish liver was identified using Raman microspectroscopy. Results revealed differences in the abundance, size distribution and presence of plastic additives over the investigated sites. Polyethylene-vinyl acetate (PEVA: 34% particles/g of tissue), high density polyethylene (HDPE: 24.4%) and the two smaller size classes, i.e. 3-1.2 μm and 1.2-0.45 μm, were the most abundant MPs types and size distribution found, respectively, in Bizerte channel (BC) site (Bizerte city, Tunisia). Moreover, at hepatic level data showed a significant site-dependent cytotoxicity expressed by changes in malondialdehyde (MDA) content, presence of reactive oxygen species (ROS) expressed by altered level of catalase (CAT) and glutathione-S-transferase (GST) activities and in the content of metallothioneins (MTs), as well as genotoxicity by changes in the amount of micronucleus (MN), and neurotoxicity by altered activity of acetylcholinesterase (AChE). A innovative metabolomics analysis was also performed to further investigate the distinct patterns of key metabolite changes in the liver of Serranus scriba. A total of 36 metabolites were significantly affected, mainly involved in energy, amino acid and osmolyte metabolism. These findings emphasised for the first time a close relationship between the source, abundance and size ranges of environmental MPs ≤ 3 μm and their hepatotoxicity in wild organisms.

Source risk, ecological risk, and bioeffect assessment for polycyclic aromatic hydrocarbons (PAHs) in Laizhou Bay and Jiaozhou Bay of Shandong Peninsula, China

In order to incorporate the contribution of pollution sources to ecological risks into environmental monitoring, positive matrix factorization-risk quotient (PMF-RQ) was used to quantify the contribution of different PAH sources to ecological risks, which indicated that the unburned petroleum, vehicular emissions, and diesel combustion were the main sources of PAHs in Laizhou Bay and Jiaozhou Bay, and they were caused by petrochemical industry, maritime shipping, and urban traffic exhaust as the major sources of PAHs for ecological risk. Meanwhile, integrated biomarker response (IBR) and multi-biomarker pollution index (MPI) suggested that September was the most polluted month for PAHs in Laizhou Bay and Jiaozhou Bay and the pollution in Laizhou Bay was significantly higher than that in Jiaozhou Bay. This research was dedicated to explore the monitoring pattern for PAH pollution from the source to bioeffects, and it may have contributed a scientific support to monitoring and governance of marine PAH pollution.

Abundance and distribution of small microplastics (≤ 3 μm) in sediments and seaworms from the Southern Mediterranean coasts and characterisation of their potential harmful effects

Microplastics (MPs) are an uncontrolled contaminant affecting marine ecosystems. Studying their undesirable effects has been an attractive field for scientists in recent years. This study is the first to investigate the uptake and distribution of small microplastics (≤3 μm) from several sites in the Southern Mediterranean coasts. This work primarilyaims to provide a qualitative and quantitative analysis of microplastics in sediments as well as in the seaworms (Hediste diversicolor) from eight sites from the Tunisian coasts using Fourier transform infrared spectroscopy and Raman microspectroscopy. The second aim is to evaluate the potential toxic effects of environmental microplastics using a set of biomarkers such as Catalase, Glutathione-S-Transferase, Malondialdehyde and Acetylcholinesterase. Our findings showed that microplastics (1 mm-1.2 μm) were present in all sediments with its abundance ranging from 129 to 606 items kg^-1. Microplastic accumulation in seaworms (3 μm-0.22 μm) was 0.5-3.7 items g^-1. The predominant polymer was polyethylene. Results also revealed a significant variation among sites in the parameters associated with oxidative stress. Thus, size abundance of microplastics in seaworms was mainly correlated with oxidative stress biomarkers. Our data should be carefully considered in view of the microplastic presence with several types and sizes in Tunisian coastal sites, their potential toxic effects, and their transfer into food web.

A verification of correlation between chemical monitoring and multi-biomarker approach using clam Ruditapes philippinarum and scallop Chlamys farreri to assess the impact of pollution in Shandong coastal area of China

Biogeochemical monitoring coupled with multi-biomarker approach were performed for the assessment of marine environment, using clam Ruditapes philippinarum and scallop Chlamys farreri to indicate contamination status in sediments and seawater respectively. The bivalves were collected from three stations, Jiaozhou Bay, Rushan Bay and Laizhou Bay, of Shandong coastal area. A series of contaminants (PAHs and TBBPA) and biomarkers (AhR, EROD, GST, SOD, GPx, CAT, DNA damage) were measured. Multi-biomarker pollution index (MPI) and integrated biomarker response (IBR) were carried out to evaluate contamination status and both indexes showed that Rushan Bay was most polluted, where the pollution level of sediments reached "highly polluted" in August, followed by Jiaozhou Bay and Rushan Bay which reached "lightly polluted". The correlation of IBR values with contaminants' concentrations was verified through the Pearson correlation coefficient (p < 0.05), consolidating this scientific assessment method for marine environment.

Oxidative Stress and Damage Biomarkers in Clam Ruditapes decussatus Exposed to a Polluted Site: The Reliable Biomonitoring Tools in Hot and Cold Seasons

In the present study, a multi-biomarker approach was used to assess the biological effects of metal pollution in the southern lagoon of Tunis, on clam Ruditapes decussatus both in "hot" (in summer) and "cold" (in winter) seasons. Clams were collected in August 2015 and February 2016 from three sites of the lagoon and from Louza considered a reference site. The concentrations of five trace metals (cadmium, copper, iron, lead, and zinc) in the soft tissues of R. decussatus were evaluated at the sampling sites. A core of biomarkers indicative of (a) neurotoxicity (acetylcholinesterase, AChE); (b) biotransformation (glutathione S-transferase, GST); (c) oxidative stress (catalase, CAT; total glutathione peroxidase, T-GPx; total glutathione peroxidase, T-GPx; selenium-dependent glutathione peroxidase, Se-GPx; glutathione reductase, GR; superoxide dismutase, SOD) (d) lipid peroxidation (malondialdhyde, MDA level), and (e) apoptotic process (caspase 3-like, CSP3) was selected for measurements of environmental effects on the populations of clams collected from the different sampling sites. The results of metal bioaccumulation in soft tissues of Ruditapes decussatus revealed a high pollution in the South Lagoon of Tunis with spatial variation and relatively high levels at the navigation channel. Anthropogenic pollutants in the lagoon led to the activation of antioxidant defense and biotransformation enzymes to oxidative damage of the membrane and activation of apoptosis, and revealed neurotoxicity. Among this core of biomarkers, the antioxidants enzymes (CAT, SOD, GR, and GPx) were very sensitive, allowing the discrimination among sites and pointing to the navigation channel as the most impacted site in the southern lagoon of Tunis. Moreover, a significant effect of season was recorded on biomarkers responses (e.g., CAT, GR, SOD, AChE, and CSP3 activities and MDA levels) with higher levels in winter than in summer, probably influenced by the reproductive stage and food availability. Finally, the measurement of the selected core of biomarkers in the whole soft tissues of clams was considered as an integrated indicator of environmental stress. Moreover, R. decussatus proved to be a remarkable sentinel species capable to establish a reliable diagnosis of the health status of the marine environment in different areas of the southern lagoon of Tunis, both in "hot" and "cold" seasons.

Using multi-integrated biomarker indexes approach to assess marine quality and health status of marine organism: a case study of Ruditapes philippinarum in Laizhou Bay, China

With the progress of technology and the deepening of understanding of biological monitoring, much more attention has been paid to the multiple evaluation of marine pollution monitoring. In view of this, our study aimed at establishing a multi-integrated biomarker indexes approach to evaluate marine condition systematically and comprehensively. In the current study, sampling was conducted in Laizhou Bay, China (S1, S2, and S3) in May, August, and October of 2015. And then, multi-integrated biomarker indexes approach was applied to assess marine PAHs pollution, select appropriate biomarkers, and evaluate marine environmental quality and health status of the clams of Ruditapes philippinarum. As the results showed, S2 was the most PAHs-polluted site while S1 was the least polluted site, and the levels of tPAHs in seawater and sediments ranged from 69.78 to 315.30 ng/L and 163.19 to 565.17 ng/g d.w., respectively. And all three sampling sites had different sources of PAHs. IBR represented DNA damage (F value), the expression of SOD, EROD activity, GST activity, and LPO could be served as biomarkers to monitor the PAHs pollution in Laizhou Bay. And MPI suggested the quality of all three sites: S1 was generally favorable, S2 was moderately polluted, and S3 was lightly polluted. BRI values showed that the order of health status of R. philippinarum was S1 > S3 > S2.

Heavy metals accumulation and endocrine disruption in Prochilodus argenteus from a polluted neotropical river

Heavy metals are considered major pollutants of aquatic environments due to the difficulty of metabolization and the bioaccumulative potential in tissues of aquatic organisms, especially fish muscle that is often used as food worldwide. In addition to causing cell damage, some metals such as aluminium (Al), cadmium (Cd), copper (Cu), and lead (Pb) can act as endocrine disrupting chemicals in fish. The Paraopeba and Abaete Rivers are important tributaries of the upper São Francisco River basin, but the Paraopeba River receives, along its course, the discharge of many types of effluents that affect fish species, including widely consumed species such as Prochilodus argenteus. This study evaluated histological and molecular changes caused by chronic exposure to heavy metals in P. argenteus from the Paraopeba River and compared this to fish from the non-impacted Abaete River. Sampled fish from both rivers were used in histological analyses and immunohistochemical assays. The results showed increased incidence of histopathologies and changes in number and morphology of germline cells in both sexes. In addition, up-regulated expression of oestrogens-induced proteins in the liver of males were detected in polluted environment. All the alterations were related to the concentration of metals in water and fish. The high concentration of various metals observed in water and fish from Paraopeba River serves as an alert to the environmental and public health regulatory authorities.

Risk assessment of occupational exposure to heavy metal mixtures: a study protocol

Background

Sfax is a very industrialized city located in the southern region of Tunisia where heavy metals (HMs) pollution is now an established matter of fact. The health of its residents mainly those engaged in industrial metals-based activities is under threat. Indeed, such workers are being exposed to a variety of HMs mixtures, and this exposure has cumulative properties. Whereas current HMs exposure assessment is mainly carried out using direct air monitoring approaches, the present study aims to assess health risks associated with chronic occupational exposure to HMs in industry, using a modeling approach that will be validated later on.

Methods

To this end, two questionnaires were used. The first was an identification/descriptive questionnaire aimed at identifying, for each company: the specific activities, materials used, manufactured products and number of employees exposed. The second related to the job-task of the exposed persons, workplace characteristics (dimensions, ventilation, etc.), type of metals and emission configuration in space and time.

Indoor air HMs concentrations were predicted, based on the mathematical models generally used to estimate occupational exposure to volatile substances (such as solvents).

Later on, and in order to validate the adopted model, air monitoring will be carried out, as well as some biological monitoring aimed at assessing HMs excretion in the urine of workers volunteering to participate.

Lastly, an interaction-based hazard index HI_int and a decision support tool will be used to predict the cumulative risk assessment for HMs mixtures.

Discussion

One hundred sixty-one persons working in the 5 participating companies have been identified. Of these, 110 are directly engaged with HMs in the course of the manufacturing process. This model-based prediction of occupational exposure represents an alternative tool that is both time-saving and cost-effective in comparison with direct air monitoring approaches. Following validation of the different models according to job processes, via comparison with direct measurements and exploration of correlations with biological monitoring, these estimates will allow a cumulative risk characterization.

Molecular cloning, characterization and expression analysis of metallothionein in the liver of the teleost Acrossocheilus fasciatus exposed to cadmium chloride

Metallothionein (MT) has a characteristic molecular structure with a cysteine-rich content. This unique structure provides metal-binding and redox capabilities and promoting metal homeostasis and detoxification in living animals. In order to evaluate the effects of cadmium (Cd) on hepatic MT expression in the liver of Acrossocheilus fasciatus, we obtained the complete cDNA of the A. fasciatus liver MT for the first time. The MT cDNA contains a 605-bp sequence, which codes for 60 amino acids. Protein alignment showed that the similarity between MT protein sequences of A. fasciatus and those of other vertebrates (especially teleosts) was very high and a cysteine residue structure was also conserved. MT was detected in the liver, kidney, gill, testis, muscle, spleen, heart and brain tissues of A. fasciatus by tissue-specific expression analysis. After Cd exposure, Cd/hemoglobin saturation assay, immunohistochemistry and reverse-transcription quantitative PCR (RT-qPCR) were used to describe MT expression in liver tissue. These techniques indicate a sensitive response by liver MT to Cd exposure. The results suggest that A. fasciatus MT may play an important role in the detoxification processes in the liver, and also would be a useful biomarker for monitoring metal pollution in aquatic environments. In addition, A. fasciatus could be regarded as one candidate for a model species for bony fishes in ecotoxicology.

Assessing the impact of Benzo[a]pyrene on Marine Mussels: Application of a novel targeted low density microarray complementing classical biomarker responses

Despite the increasing use of mussels in environmental monitoring and ecotoxicological studies, their genomes and gene functions have not been thoroughly explored. Several cDNA microarrays were recently proposed for Mytilus spp., but putatively identified partial transcripts have rendered the generation of robust transcriptional responses difficult in terms of pathway identification. We developed a new low density oligonucleotide microarray with 465 probes covering the same number of genes. Target genes were selected to cover most of the well-known biological processes in the stress response documented over the last decade in bivalve species at the cellular and tissue levels. Our new ‘STressREsponse Microarray’ (STREM) platform consists of eight sub-arrays with three replicates for each target in each sub-array. To assess the potential use of the new array, we tested the effect of the ubiquitous environmental pollutant benzo[a]pyrene (B[a]P) at 5, 50, and 100 μg/L on two target tissues, the gills and digestive gland, of Mytilus galloprovincialis exposed invivo for three days. Bioaccumulation of B[a]P was also determined demonstrating exposure in both tissues. In addition to the well-known effects of B[a]P on DNA metabolism and oxidative stress, the new array data provided clues about the implication of other biological processes, such as cytoskeleton, immune response, adhesion to substrate, and mitochondrial activities. Transcriptional data were confirmed using qRT-PCR. We further investigated cellular functions and possible alterations related to biological processes highlighted by the microarray data using oxidative stress biomarkers (Lipofuscin content) and the assessment of genotoxicity. DNA damage, as measured by the alkaline comet assay, increased as a function of dose.DNA adducts measurements using ³²P-postlabeling method also showed the presence of bulky DNA adducts (i.e. dG-N²-BPDE). Lipofiscin content increased significantly in B[a]P exposed mussels. Immunohistochemical analysis of tubulin and actin showed changes in cytoskeleton organisation. Our results adopting an integrated approach confirmed that the combination of newly developed transcriptomic approcah, classical biomarkers along with chemical analysis of water and tissue samples should be considered for environmental bioimonitoring and ecotoxicological studies to obtain holistic information to assess the impact of contaminants on the biota.

A baseline study of the metallothioneins induction and its reversibility in Neohelice granulata from the Bahía Blanca Estuary (Argentina)

Contamination by heavy metals causes serious effects in marine systems. Nowadays, the combination of chemical and biological data is recommended in monitoring programs. Metallothioneins (MT) are early-warning signals of metal exposure and are widely used in biomonitoring. The present research evaluates the heavy metals levels in sediments and the MT synthesis in the crab Neohelice granulata from the Bahía Blanca Estuary (BBE). Then, the recovery capabilities of N. granulata followed by a depuration phase are assessed. Results demonstrate a slow decline in the level of metals in the study area. In relation to MT, female crabs showed elevated MT when compared to males. Furthermore, MT synthesis diminished after the depuration phase. These data constitute the first MT information in organisms from the BBE and may be considered as baseline for future studies in this matter. Although pollution level found was low, further biomonitoring considering both types of data is recommended.

Combined effects of metal contamination and abiotic parameters on biomarker responses in clam Ruditapes decussatus gills: an integrated approach in biomonitoring of Tunis lagoon

The spatial and seasonal alteration in a battery of biomarkers responses (enzymatic activity of glutathione-S-transferase, catalase and acetylcholinesterase and lipid peroxidation) were investigated to assess the metal derived effects in clam (Ruditapes decussatus) gills, collected from Tunis lagoon (Tunisia). Trace metals (Ag, As, Cd, Cu, Hg, Mn, Ni, Pb, V and Zn) concentrations were assessed seasonally in sediments and tissues of R. decussatus from three different sites (S1, S2 and S3). Bioaccumulation factor (BAF) analysis showed a spatio-temporal variation of metal uptake rates in clams through sediments. Likewise, the multibiomarker approach enabled a time-site trend differentiation between sites with distinctive degrees of anthropogenic contamination. Site S2 was identified as the most impacted region due to the presence of different contamination sources (shipping and industrial activities). The results suggest that biomarker's seasonal variation arises from a complex interaction between environmental conditions (e.g. temperature, salinity) and probably biological factors (mainly the reproduction process) along with anthropogenic pressure. The general biological response measured with the IBR index at all the sampling sites revealed the highest metabolic stress in summer. The combined effects of metal contamination and increased temperature and salinity in summer appear to induce the highest metabolic adaptation response. The selected biomarkers provided an integrated response, which is useful for the assessment of the combined effects of metal contamination and abiotic parameters in clams and the environmental status of coastal lagoon ecosystem.

Heavy metal accumulation in Diplodus annularis, Liza aurata, and Solea vulgaris relevant to their concentration in water and sediment from the southwestern Mediterranean (coast of Sfax)

The concentrations of heavy metals (Cd, Cu, Fe, Pb, Ni, and Zn) were measured in the liver, gills, and muscle of Solea vulgaris, Liza aurata, and Diplodus annularis, collected from the south coast of Sfax (Gabes Gulf, southwestern Mediterranean). The concentrations of heavy metals in water exhibited the following decreasing order (expressed in μg l(-1)): Fe > Ni > Zn > Cu > Pb > Cd whereas the trend is somewhat different in sediments (mg kg(-1) D.W.) Fe > Zn > Pb > Ni > Cu > Cd. The levels of heavy metals varied significantly among fish species and tissues. Heavy metal levels were found generally higher in the liver and gills than the muscle in all species. The liver was the target organ for Cd, Cu, Fe, Ni, and Zn accumulation. Nickel and lead, however, exhibited their highest concentrations in the gills. The three studied fishes showed a difference in metals accumulation decreasing in following order S. vulgaris > D. annularis > L. aurata. Solea vulgaris with the highest TFwater, TFsediment, and metal concentrations in tissues would be considered as a potential bio-indicator in the south coast of Sfax for the assessment of environmental pollution status. Comparative studies with Luza zone indicate considerable bioaccumulation of heavy metals (Pb and Zn) in the various tissues of fish samples of the south coast of Sfax.

Using environmental proteomics to assess pollutant response of Carcinus maenas along the Tunisian coast

Biochemical responses to pollutants were studied at four Tunisia littoral sites using Carcinus maenas as a bioindicator. Proteomic analysis was used to assess the global impact of complex pollution mixtures, and to provide new biomarkers and basic insights into pollutant toxicity. Metal contents and metallothionein levels followed a gradient based on sampling sites: Bizerte ≫ Teboulba > Gargour~Mahres. Approximately 900 and 700 spots were resolved in digestive glands and gills, respectively. Gills from Bizerte animals had the maximum number of altered spots, mostly upregulated. In other locations, the number of altered spots in gills decreased in parallel to total metals in in the following order: Teboulba > Gargour > Mahres (mostly downregulated). Out of the 39 spots excised, ten proteins were identified in digestive glands and eight in gills. Digestive glands of Bizerte crabs had higher levels of ferritin, three vitellogenin forms and mannose-binding protein, while Gargour crabs had higher levels of four cryptocyanin forms. Gills of Bizerte crabs had higher levels of ferritin, three vitellogenins forms, lectin 4C, actin, and collagenolytic serine protease. Proteins with altered expression in crabs from Tunisia littoral are related to molting, oxidative stress and inflammation, innate immune response, and proteolysis.

What factors drive the variations of phytoplankton, ciliate and mesozooplankton communities in the polluted southern coast of Sfax, Tunisia?

We studied the spatial distribution of phytoplankton, ciliate and mesozooplankton communities coupled with environmental factors in the southern coast of Sfax (central eastern coastline of Tunisia). Phytoplankton assemblages were dominated by Dinophyceae (69.99%) and Bacillariophyceae (15.88%). The ciliate community consisted of Spirotrichea with a dominance of Tintinnopsis beroidea (57.69%). The mesozooplankton community was dominated by copepods representing 66.12% of the total zooplankton. Oithona nana showed a high frequency mainly in stations 9 and 10 with 66.86 and 64.65%, respectively. Some toxic phytoplankton species were recorded in the present study site. For this reason, the pollution generated in this area presents a slight degradation of the water quality and can be responsible for the bloom generated by the high proliferation of these toxic microalgae. The pollution generated by industrial activities has an effect on the spatial distribution of phytoplankton, ciliate and copepod communities with a reduction of their diversity indexes.

Induction of brown cells in Venerupis philippinarum exposed to benzo(a)pyrene

Benzo(a)pyrene is an important polycyclic aromatic hydrocarbon (PAH) commonly present in the marine environment and responsible for carcinogenic, teratogenic and mutagenic effects in various animal species. In the present study, we investigated by both histochemical and immunohistochemical approaches the effect of an acute exposure to different concentrations of B(a)P in the Manila clam Venerupis philippinarum. The general morphology of the different clam tissues, which was investigated histologically, evidenced a significant increase in the number of intestinal brown cells after B(a)P exposure. An increasing trend response to B(a)P was detected. The histochemical analysis for lipofuscin revealed the presence of lipofuscin-like substances inside the cytoplasm of intestinal brown cells. The same cells exhibited a PAS positivity and a reactivity to Schmorl's solution for melanin pigment. Moreover, intestinal brown cells exhibited an immunopositivity to HSP70 antibody confirming the increasing trend response to B(a)P detected by the histochemical analysis. Our results suggest that histological tissue changes resulting from exposure to B(a)P can be an useful marker in biomonitoring studies.

Histopathology and stress biomarkers in the clam Venerupis philippinarum from the Venice Lagoon (Italy)

The aim of this study was to evaluate the histomorphology and the stress response in the bivalve Venerupis philippinarum sampled in four differently polluted sites of the Venice Lagoon (Palude del Monte, Marghera, Ca' Roman and Val di Brenta). This species is often used as bioindicator of environmental pollution since it can bioaccumulate a large variety of pollutants because of its filter feeding. Chemical analyses for heavy metals (Cd, Cu, Hg and Pb) and polycyclic aromatic hydrocarbons (PAHs) were performed on whole soft tissues of V. philippinarum. The histological evaluation of clams revealed the presence of Perkinsus sp. infection in animals from all sites, although a very high prevalence of parasites was evidenced in clams from Ca' Roman. Perkinsus sp. were systemically distributed in the mantle, in the intestine and digestive gland, in gonads and gills. The trophozoites of Perkinsus sp. were found isolated or in cluster surrounded by a heavy hemocitical response. Haemocytes always exhibited an immunopositivity to cytochrome P4501A (CYP1A), heat shock protein 70 (HSP70), 4-hydroxy-2-nonenal (HNE) and nitrotyrosine (NT) antibodies. The digestive gland of animals from Palude del Monte showed the highest malondialdehyde (MDA) concentration, whereas clams from Ca' Roman exhibited the highest quantity of metallothioneins.

The role of biomarkers in the assessment of aquatic ecosystem health

Ensuring the health of aquatic ecosystems and identifying species at risk from the detrimental effects of environmental contaminants can be facilitated by integrating analytical chemical analysis with carefully selected biological endpoints measured in tissues of species of concern. These biological endpoints include molecular, biochemical, and physiological markers (i.e., biomarkers) that when integrated, can clarify issues of contaminant bioavailability, bioaccumulation, and ecological effects while enabling a better understanding of the effects of nonchemical stressors. In the case of contaminant stressors, an understanding of chemical modes of toxicity can be incorporated with diagnostic markers of aquatic animal physiology to help understand the health status of aquatic organisms in the field. Furthermore, new approaches in functional genomics and bioinformatics can help discriminate individual chemicals, or groups of chemicals among complex mixtures that may contribute to adverse biological effects. Although the use of biomarkers is not a new paradigm, such approaches have been underused in the context of ecological risk assessment and natural resource damage assessment. From a regulatory standpoint, these approaches can help better assess the complex effects from coastal development activities to assessing ecosystem integrity pre- and post development or site remediation.

Expression patterns of metallothionein, cytochrome P450 1A and vitellogenin genes in western mosquitofish (Gambusia affinis) in response to heavy metals

The aim of this study was to evaluate the effects of three metals (Zn, Cd and Pb) on hepatic metallothionein (MT), cytochrome P450 1A (CYP1A) and vitellogenin (Vtg) mRNA expression in the liver of adult female mosquitofish (Gambusia affinis) after 1, 3 or 8d. Both concentration-response and time-course effects of hepatic MT, CYP1A and Vtg at the transcription level were determined by quantitative real-time PCR. The results from this study showed that Zn, Cd and Pb could significantly induced MT, CYP1A and Vtg mRNA expression levels in mosquitofish. In general, this study demonstrated that heavy metals modulate MT, CYP1A and Vtg mRNA expression levels in a metal-, concentration- or time-dependent manner.

Interspecific and geographical variations of trace metal concentrations in cephalopods from Tunisian waters

The concentrations of six metals (Ag, Cd, Cu, Hg, Pb, and Zn) were investigated and compared in three tissues (arms, digestive gland, and mantle) of three cephalopod species from the Tunisian waters: the common octopus (Octopus vulgaris), the common cuttlefish (Sepia officinalis), and the European squid (Loligo vulgaris). Whatever the species or the sites, the digestive gland displayed the highest concentrations of Ag, Cd, Cu, Pb, and Zn, highlighting its major role in their bioaccumulation and detoxification. This is also true for Hg but only for the digestive gland of O. vulgaris. Muscle from the arms and the mantle contained thus relatively low trace metal concentrations except for Hg in L. vulgaris and S. officinalis. Geographic comparison of metal concentrations in Tunisian cephalopods from three locations indicates that higher concentrations of Ag, Pb, and Hg were observed in cephalopods from northern and eastern coasts, whereas the highest Cd levels were detected in the southeastern, reflecting different conditions of exposure. Comparing the trace element concentrations between species, Ag, Cd, Cu, Hg, and Zn concentrations were the highest in the digestive gland of octopuses. This may be related to the differences in ecological features and swimming behavior among different cephalopod species. Effects of length and sex on metal levels were also considered, indicating a limited influence of sex on metal concentration.

Integrated biomarkers in wild crucian carp for early warning of water quality in Hun River, North China

Metabolizing enzymes play important roles in the detoxification of various pollutants in aquatic organisms, thereby they can also be used to provide early-warning signals of environmental risks. Real-time quantitative reverse-transcription polymerase chain reaction assays were developed to quantify cytochrome P450 1A (CYP1A), superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and glutathione-S-transferase (GST) in crucian carp (Carassius auratus). The methods were then used to detect the respective mRNA expression levels in liver tissue in wild crucian carp from the Hun River, North China. CYP1A mRNA expression was significantly up-regulated in fish from stations S5, S6, and S8 (p < 0.05). SOD mRNA expression was significantly down-regulated in downstream areas relative to fish from upstream sites (p < 0.05); GPx and CAT mRNA expression levels were also down-regulated at S9 (p < 0.05). In contrast, GST mRNA expression showed no obvious change between fish collected from up- or downstream areas of the river. Finally, an integrated biomarker response was used to evaluate the integrated impact of pollutants in the Hun River and allow better comprehension of the real toxicological risk of these investigated sites.

Effects of thermal stress and nickel exposure on biomarkers responses in Mytilus galloprovincialis (Lam)

The present work aimed to assess the Mytilus galloprovincialis digestive gland biomarkers responses to nickel (Ni) exposure along with a heat stress gradient. Mussels were exposed to a sublethal dose of nickel (13 μM) along with a temperature gradient (18 °C, 20 °C, 22 °C, 24 °C and 26 °C) for 4 days. Metallothionein (MTs) content was assessed as specific response to metals. Catalase (CAT), glutathione S-transferase (GST) activities and malondialdehyde (MDA) were measured as biomarkers of oxidative stress and lipid peroxidation. The cholinergic system was monitored using the acetylcholinesterase activity (AChE). Moreover, Ni uptakes along with the exposure temperatures were assessed. A correlation matrix (CM) between the investigated biomarkers and the exposure temperatures and a Principal Component Analysis (PCA) were achieved. Our data showed a negative effect of temperature increase on mussel's antioxidant and detoxification response to Ni exposure being more pronounced in animals exposed to the 24 °C and 26 °C.

Expression of CYP4 and GSTr genes in Venerupis philippinarum exposed to benzo(a)pyrene

Bivalve molluscs, such as Venerupis philippinarum, are often used as bioindicators of environmental pollution since they can bioaccumulate a large variety of pollutants because of their filter feeding. The Polycyclic Aromatic Hydrocarbon (PAH) benzo(a)pyrene (B(a)P) is an important contaminant, commonly present in the marine environment. Pollutants are generally metabolized by enzymes of phase I, mainly CYPs enzymes, and by conjugation enzymes of phase II like GST. In this study, we investigated by Real Time PCR the expression of CYP4 and GSTr (GST class rho) in the digestive gland of V. philippinarum exposed to different concentrations of B(a)P for 24 h and after a 24 h depuration period. Accumulation of B(a)P by clams has been confirmed by the HPLC-FLD analyses. Moreover, HPLC-FLD analyses evidenced that after depuration, B(a)P concentrations decreased in animals subjected to 0.03 mg/l and 0.5mg/l exposures but did not decrease in animals subjected to 1mg/l exposure. B(a)P exposure and depuration did not cause histopathological lesions in the different organs. The analysis of GSTr expression in the digestive gland showed a significant increase in mRNA in animals subjected to 1 mg/l exposure, whereas the analysis of CYP4 expression did not evidence differences among treatments. Moreover, the expression of both genes did not exhibit any differences after the purification treatment. The results demonstrate that B(a)P significantly affects the expression of GSTr mRNA in the digestive gland of V. philippinarum and suggest that GSTr gene could play an important role in the biotransformation of B(a)P.

Effect of pharmaceuticals exposure on acetylcholinesterase (AchE) activity and on the expression of AchE gene in the monogonont rotifer, Brachionus koreanus

Pharmaceuticals are widely used in human and veterinary medicine. However, they are emerging as a significant contaminant in aquatic environments through wastewater. Due to the persistent and accumulated properties of pharmaceuticals via the food web, their potential harmful effects on aquatic animals are a great concern. In this study, we investigated the effects of six pharmaceuticals: acetaminophen, ATP; atenolol, ATN; carbamazepine, CBZ; oxytetracycline, OTC; sulfamethoxazole, SMX; and trimethoprim, TMP on acetylcholinesterase (AChE; EC 3.1.1.7) activity and its transcript expression with chlorpyrifos (as a positive control) in the monogonont rotifer, Brachionus koreanus. ATP, CBZ, and TMP exposure also remarkably inhibited Bk-AChE activity at 100 μg/L (24 h) and 1000 μg/L (12 h and 24 h). ATP, CBZ, and TMP exposure showed a significant decrease in the Bk-AChE mRNA level in a concentration-dependent manner. However, in the case of OTC and SMX, a slight decrease in Bk-AChE mRNA expression was found but only at the highest concentration. The time-course experiments showed that ATP positively induced Bk-AChE mRNA 12 h after exposure at both 100 and 1000 μg/L, while the Bk-AChE mRNA expression was significantly downregulated over 6 to 24 h after exposure to 1000 μg/L of CBZ, OTC, SMX, and TMP. Our findings suggest that Bk-AChE would be a useful biomarker for risk assessment of pharmaceutical compounds as an early signal of their toxicity in aquatic environments. Particularly, ATP, CBZ, and TMP may have a toxic cholinergic effect on rotifer B. koreanus by inhibiting AChE activity.

Biochemical responses in seabream (Sparus aurata) caged in-field or exposed to benzo(a)pyrene and paraquat. Characterization of glutathione S-transferases

Gilthead seabream (Sparus aurata) specimens were caged in-field at the Téboulba harbour or exposed to benzo(a)pyrene [B(a)P] or to paraquat [PQ] plus B(a)P, and several biochemical biomarker responses were investigated. Antioxidant enzymes, such as glutathione peroxidase, catalase and glutathione reductase, significantly increased in the in-field and B(a)P+PQ exposures, but were only moderately affected by B(a)P alone. Glucose-6-phosphate and 6-phosphogluconate dehydrogenases significantly diminished after in-field exposure. Different responses with biotransformation enzymes were observed: the P4501A-associated EROD activity was highly induced in response to B(a)P and B(a)P+PQ exposures, while total activity of the glutathione S-transferase (GST) was similar to control. However, after purification of the GST proteins by affinity chromatograpy and analysis by two-dimensional electrophoresis, nineteen highly reproducible isoforms were resolved. In addition, some of reproducible isoforms showed different and specific expression patterns in response to contaminants. Thus, proteomic analysis of the purified GST subunits is a reliable tool for ecotoxicological research, useful in polluted marine ecosystem as an effective biomarker of contamination.

Increased temperatures affect oxidative stress markers and detoxification response to benzo[a]pyrene exposure in mussel Mytilus galloprovincialis

The present research work was designed to study mussel's (Mytilus galloprovincialis) digestive gland biotransformation and detoxification responses to benzo[a]pyrene (B[a]P) exposure along with heat stress. Mussels were exposed to a sublethal dose of B[a]P [75 nM (19 μg/L/animal)] + temperature gradient (18, 20, 22, 24 and 26 °C) for 7 days. B[a]P hydroxylase (BPH) and glutathione-S-transferase (GST) activities were assessed in digestive gland tissues as phase I and phase II biotransformation parameters. Catalase (CAT) activity and malonedialdehyde (MDA) were measured as potential biomarkers of oxidative stress and lipid peroxidation. The cholinergic system was evaluated using acetylcholinesterase (AChE) activity. DNA damage was assessed using micronuclei (MN) test. BPH and GST activities showed a decreasing trend in B[a]P-exposed animals at 24 and 26 °C. CAT activity showed a bell-shaped response in B[a]P-exposed and in heat-stressed organisms at a maximum temperature of 22 °C. AChE activity was significantly inhibited in response to B[a]P being more pronounced at a temperature of 26 °C. MN in digestive gland cells suggest that B[a]P exposure induced significant DNA alteration with a maximum response in organisms coexposed to B[a]P and a temperature of 26 °C. Biomarker data are further discussed in relation B[a]P accumulation in mussels digestive gland. These data should be carefully considered in view of the biological effects of organic pollutants, particularly in organisms under the challenging effects of extreme temperature fluctuations.

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

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

Integrated use of biomarkers in the mussel Mytilus galloprovincialis for assessing off-shore gas platforms in the Adriatic Sea: results of a two-year biomonitoring program

Despite a large number of gas platforms existing in the Adriatic Sea, which is a semi-enclosed basin characterized by a slow turnover rate and increasing industrial as well as other anthropogenic activities, the effects of these structures on the aquatic ecosystem require further investigation. Since 1998, multidisciplinary studies have been performed by CNR-ISMAR to comply with legislation and to support the development of protocols for the monitoring of offshore activities in the Adriatic Sea. The present study was developed to implement a biomonitoring plan to assess the ecotoxicological effects of the extraction activities of an off-shore gas platform. Biomarkers were evaluated in mussels collected from the platform in relation to physiological stress, DNA damage, cellular damage, oxidative stress and exposure effects. Organic contaminants and trace element bioaccumulation were also assessed in the soft body of the mussels to correlate bioaccumulation of pollutants with biomarker responses. The results indicate an absence of platform-related environmental stress.

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.

Uptake and biochemical responses of mussels Mytilus galloprovincialis exposed to sublethal nickel concentrations

In the present study, mussel (Mytilus galloprovincialis) digestive gland oxidative stress biomarkers and detoxification responses to acute exposure to nickel (Ni) were investigated. Mussels were exposed to two sublethal concentrations of Ni (135 μg/L per animal (2.5 μM) and 770 μg/L per animal (13 μM)) for 24, 48, 72, 96 h and 8 days. Following biological responses were measured: (1) glutathione S-transferase (GST) activity as a phase II conjugation enzyme, (2) catalase activity as antioxidant response, (3) malondialdehyde accumulation (MDA) as lipid peroxydation marker and metallothionein as specific response to metals exposure. The cholinergic system was evaluated using the acetylcholinesterase activity (AChE). Moreover, Ni uptakes during the exposure periods were assessed and the uptake rate constant determined. A correlation matrix (CM) between the investigated biomarkers and a principal component analysis (PCA) were achieved for the two tested concentrations. The Ni-uptake constant was higher in animals exposed to the lowest concentration. The CM and the PCA showed a time-dependent effect of the Ni exposure on the investigated biomarkers being more pronounced in animals exposed to the highest Ni concentration. While AChE showed a significant increase after 48 h and a further return to control values in the lowest concentration, it was drastically maintained inhibited in the highest concentration. Our data provided clues about the occurrence of different toxicokinetics and toxicodynamics of two Ni sublethal concentrations in an ecologically relevant organism.

Acute effects of benzo[a]pyrene on digestive gland enzymatic biomarkers and DNA damage on mussel Mytilus galloprovincialis

In the present study, mussel (Mytilus galloprovincialis) digestive gland biotransformation and detoxification responses to acute exposure to the polycyclic aromatic hydrocarbon benzo[a]pyrene (B[a]P) were investigated. Mussels were exposed to a sublethal dose of B[a]P (75 nM; 19 microg/l per animal) for 24, 48 and 72h. The following biological responses were measured in the digestive gland tissues: (1) B[a]P hydroxylase (BPH) activity, as phase I biotransformation parameter; (2) glutathione S-transferase (GST) activity as a phase II conjugation enzyme, (3) catalase (CAT) activity as potential biomarker of oxidative stress, (4) acetylcholinesterase (AChE) activity as an indication of possible neurotoxicity response. DNA damage was assessed over time using the single cell gel electrophoresis comet assay and the micronuclei test. BPH and GST activities showed an increasing trend over exposure period. CAT activity showed a symmetrical bell shape response with a maximum at 48h. AChE activity was significantly depressed after 48 and 72h exposure to B[a]P. Comet assay and micronuclei test in digestive gland cells suggest that B[a]P exposure induced significant DNA damage with a maximum response after 72h exposure.

Monitoring pollution in Tunisian coasts using a scale of classification based on biochemical markers in worms Nereis (Hediste) diversicolor

This paper aims to assess the marine environment quality along the Tunisian coasts using a statistical approach based on biomarkers response in the polychaete worms Nereis (Hediste) diversicolor. Worms were collected from six sites: Bizerta Lagoon, Gargour, Nakta, Mahres, Skhira and from Teboulba considered as a reference site. The biomarkers selected in this work were (1) the activities of cytochrome P450-dependent NADPH cytochrome c reductase (NADPH red) as phase I enzyme, (2) glutathione S-transferase as phase II enzyme and (3) the acetylcholinesterase activity as neurotoxicity marker. Oxidative stress was evaluated using catalase activity and malondialdehyde accumulation. For each biomarker, a discriminatory factor was calculated and a response index was allocated. For each site, a multi-marker pollution index was calculated as the sum of the response index of each of the five more discriminating biomarkers. The results show differences between sites compared with the reference samples. The multi-marker approach confirms that worms from Bizerta and Mahress have been submitted to highly polluted environment. Mahress shows the highest multi-marker pollution index, indicating a highly contamination status.

Metallothionein and metal levels in liver, gills and kidney of Sparus aurata exposed to sublethal doses of cadmium and copper

The levels of metallothionein (MT), a biomarker of metal exposure, and of Cd and Cu, known as MT inducers, were investigated in Sparus aurata intraperitoneally injected with 500 microg/kg of Cu and Cd for 2 days. MT and metal concentrations (Cd and Cu) were determined in liver, gills and kidney. MT levels were significantly increased in all investigated tissues, with the highest value in liver of Cu as Cd-treated fishes (3.56-fold and 3.3- fold, respectively). Metal concentrations were statistically different between all tissues. Highest metal concentrations were in the liver. The higher metal concentrations and MT induction levels support the main role of MT in metal homeostasis and detoxification.

Mixture toxicity assessment of cadmium and benzo[a]pyrene in the sea worm Hediste diversicolor

In the present study, Hediste diversicolor biotransformation and anti-oxidant responses to acute exposure to cadmium (Cd) and to the polycyclic aromatic hydrocarbons benzo[a]pyrene (B[a]P) were investigated. Worms were submitted to 0.2, 0.4 and 1 microM of each contaminant and to their mixture during a period of test of 48h. Following biological responses were measured: (1) NADPH cytochrome c reductase (NADPH cyt c) activity, as phase I biotransformation parameter; (2) gluthathione-S-transferase (GST) activity as a phase II conjugation enzyme, (3) catalase activity as anti-oxidant response and (4) malondialdehyde accumulation (MDA) as lipid peroxydation marker. The cholinergic system was evaluated using the acetylcholinesterase activity (AChE). Exposure to the mixture resulted in low dose level additive effects on the investigated biomarkers. However, worms exposed to 1 microM of the single compounds and to their mixture exhibited the highest MDA accumulation and the lowest enzymatic biomarkers activities suggesting severe toxicological effects. These data should be carefully considered in view of the biological effects of mixture pollutants and particularly in marine sediment ecosystems.

Evaluation of enzymatic biomarkers and lipoperoxidation level in Hediste diversicolor exposed to copper and benzo[a]pyrene

This study aims to evaluate the effects of exposure to copper, benzo[a]pyrene, and to their mixture on enzymatic and lipid peroxidation biomarkers in Hediste diversicolor. Worms were submitted to 1 microM of both single compounds and to their mixture during a period of test of 12, 24, 36, and 48 h. The biomarkers selected in this work were the activities of cytochrome P450-dependent NADPH cytochrome c reductase (NADPH red) as phase I enzyme, glutathione-S-transferase (GST) as phase II enzyme, and the acetylcholinesterase (AChE) activity as neurotoxicity marker. Oxidative stress was evaluated using catalase activity (CAT) and malondialdehyde accumulation (MDA). The NADPH red activity was not significantly affected by copper exposure; it shows a drastic increase in both B[a]P and mixture-exposed organisms. GST activities were significant in B[a]P-exposed worms only after 36 h, and in animals exposed to the mixture after 12 and 48 h. The ACHE activity was inhibited only in B[a]P-exposed worms.

Seasonal variation of oxidative stress biomarkers in clams Ruditapes decussatus sampled from Tunisian coastal areas

Seven (7) sites from to the Tunisian coastal area were monitored through four seasons using several oxidative stress biomarkers including lipid peroxidation. Catalase (CAT) specific activity was determined in clam Ruditapes decussatus digestive gland. Lipid peroxidation was assessed in the same tissues using malondialdehyde (MDA) concentration, neutral lipid (NL) and lipofuscin accumulation. Results show that catalase specific activity varies between sites and fluctuates in time. The highest CAT activities were recorded in sites from Bizerta Lagoon and sites neighbouring Sfax city. Malondialdehyde accumulation in digestive gland cells seems to be very pronounced in animals sampled in summer and autumn. Digestive gland sections of clams sampled from reported heavy metal polluted sites exhibited higher volume density of residual bodies. Our results showed that the neutral lipids and lipofuscin content in clam's digestive gland are more sensitive to general stress as compared to other biomarkers, and could be used successfully in clams as early warning tools in field biomonitoring programs.

Acute effects of benzo[a]pyrene on liver phase I and II enzymes, and DNA damage on sea bream Sparus aurata

In the present study biotransformation and detoxification responses to acute exposure to the polycyclic aromatic hydrocarbons benzo[a]pyrene (B[a]P) were investigated in the liver of Sparus aurata (sea bream). Sexually immature gilthead sea bream were treated by intraperitoneal injection of B[a]P (20 mg kg(-1)) for 6, 12, 24, and 48 h. B[a]P accumulation was quantified in sea bream liver by mean of gas phase chromatography (GPC-MS) after the various exposure periods. The following biological responses were measured: (1) ethoxyresorufin-O-deethylase (EROD) activity, as a phase I biotransformation parameter; (2) liver glutathione S-transferase (GST) activity as a phase II conjugation enzyme. DNA damage was assessed over time using the single-cell gel electrophoresis comet assay. B[a]P bioaccumulation in the liver resulted in a biphasic curve with an increasing uptake up to 5.55 +/- 0.67 microg g(-1) dry weight after only 6 h exposure and 4.67 +/- 0.68 microg g(-1) dry weight after 48 h exposure. EROD activity showed a nonsymmetrical bell-shaped kinetic with a maximum at 24 h and lower but significant activities at 12 and 48 h with respect to control animals. Hepatic GST activities were only significant after 48 h exposure. Comet assay showed an increase in liver cells DNA damage with a maximum after 48 h exposure reaching up to 12.17 % DNA in the tail.

Involvement of cd bioaccumulation in spinal deformities occurrence in natural populations of Mediterranean killifish

The aim of this study was to investigate the possible influence of environmental exposure to cadmium (Cd) on the spinal deformities occurrence in the Mediterranean killifish, Aphanius fasciatus (Pisces: Cyprinodontidae). For this purpose, some indicators of skeletal bone mineralization, Cd, and calcium (Ca) concentrations in spinal column as well as bioaccumulation of Cd from the water and the sediment have been compared in normal and deformed fish collected from polluted (S1) and nonpolluted (S2) areas in the Gulf of Gabès in Tunisia. When compared to the normal fish, the deformed fish showed signs of spinal column demineralization such as significant decrease in the ash weight/dry weight ratio, percentage of nonorganic components content, and Ca concentration. Cd concentrations in spinal column and liver were significantly higher in deformed fish than in normal fish. A highly significant negative correlation (r = -0.915, p < 0.01) between Cd and Ca concentrations was noted in spinal column of deformed fish. Bioaccumulation factors of Cd in the liver from the water and the sediment in deformed fish were also significantly higher (p < 0.0001) than in normal fish from S1 and S2. These findings suggest that the ability to accumulate large amount of Cd may represent a potential risk to induce spinal deformities in natural populations of Mediterranean killifish.

Cadmium bioaccumulation in three benthic fish species, Salaria basilisca, Zosterisessor ophiocephalus and Solea vulgaris collected from the Gulf of Gabes in Tunisia

To select a marine teleost fish which can be used as a bioindicator of cadmium (Cd) pollution in the Gulf of Gabes in Tunisia, Cd concentrations in liver and gill were compared in three benthic fish species including Salaria basilisca, Zosterisessor ophiocephalus and Solea vulgaris. Fish samples were collected from three selected sites in the Gulf of Gabes, with different degrees of Cd contamination: the industrialized coast of Sfax (S1), the coast of Douar Chatt (S2) and the coast of Luza (S3). The results shows that Cd concentrations in both sediment and water collected from S1 were significantly higher (p < 0.0001) than those from S2 and S3. For each species, Cd concentrations, in both liver and gill, showed the decreasing order: S1 > S2 > S3. The highest concentration of Cd was detected in the liver of S. basilisca, and only S. basilisca showed bioaccumulation factors (BAF) greater than 1 in all studied sites. In S1 and S2, BAF values respect the following order: S. basilisca > Z. ophiocephalus > S. vulgaris. These results of significant bioaccumulation of Cd, in terms of hepatic concentrations and bioaccumulation factors, indicated that S. basilisca can be used as bioindicator to evaluate the evolution of Cd pollution in the Gulf of Gabes.

Acute effects of chlorpyryphos-ethyl and secondary treated effluents on acetylcholinesterase and butyrylcholinesterase activities in Carcinus maenas

The acute effects of commercial formulation of chlorpyrifos-ethyl (Dursban) and the secondary treated industrial/urban effluent (STIUE) exposure on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities in hepatopancreas and gills of Mediterranean crab Carcinus maenas were investigated. After 2 d of exposure to chlorpyriphos-ethyl, the AChE activity was inhibited in both organs at concentrations of 3.12 and 7.82 microg/L, whereas the BuChE was inhibited only at higher concentration 7.82 microg/L of commercial preparation Dursban. The exposure of crabs to Dursban (3.12 microg/L) showed a significant decrement of AChE activity at 24 and 48 h, whereas the BuChE was inhibited only after 24 h and no inhibition for both enzymes was observed after 72 h. Moreover, a significant repression of AChE activity was observed in both organs of C. maenas exposed to 5% of STIUE. Our experiments indicated that the measurement of AChE activity in gills and hepatopancreas of C. maenas would be useful biomarker of organophosphorous (OP) and of neurotoxic effects of STIUE in Tunisia.

Integrated use of biomarkers and bioaccumulation data in Zebra mussel (Dreissena polymorpha) for site-specific quality assessment

One of the useful biological tools for environmental management is the measurement of biomarkers whose changes are related to the exposure to chemicals or environmental stress. Since these responses might vary with different contaminants or depending on the pollutant concentration reached in the organism, the support of bioaccumulation data is needed to prevent false conclusions. In this study, several persistent organic pollutants -- 23 polychlorinated biphenyl (PCB) congeners, 11 polycyclic aromatic hydrocarbons (PAHs), six dichlorodiphenyltricholroethane (DDT) relatives, hexachlorobenzene (HCB), chlorpyrifos and its oxidized metabolite -- and some herbicides (lindane and the isomers alpha, beta, delta; terbutilazine; alachlor; metolachlor) were measured in the soft tissues of the freshwater mollusc Zebra mussel (Dreissena polymorpha) from 25 sampling sites in the Italian portions of the sub-alpine great lakes along with the measure of ethoxyresorufin dealkylation (EROD) and acetylcholinesterase (AChE) activity. The linkage between bioaccumulation and biomarker data allowed us to create site-specific environmental quality indexes towards man-made chemicals. This classification highlighted three different degrees of xenobiotic contamination of the Italian sub-alpine great lakes: a high water quality in Lake Lugano with negligible pollutant levels and no effects on enzyme activities, an homogeneous poor quality for Lakes Garda, Iseo and Como, and the presence of some xenobiotic point-sources in Lake Maggiore, whose ecological status could be jeopardized, also due to the heavy DDT contamination revealed since 1996.

Development of an expert system for the integration of biomarker responses in mussels into an animal health index

Biomarkers on sentinel organisms are utilised worldwide in biomonitoring programs. However, the lack of effective interpretational capacity has hampered their uptake for use for assessment of risk in environmental management. The aim of the present study was to develop and test an objective decision-support or expert system capable of integrating biomarker results into a five-level health-status index. The expert system is based on a set of rules derived from available data on responses to natural and contaminant-induced stress of marine mussels. Integration of parameters includes: level of biological organization; biological significance; mutual interrelationship; and qualitative trends in a stress gradient. The system was tested on a set of biomarker data obtained from the field and subsequently validated with data from previous studies. The results demonstrate that the expert system can effectively quantify the biological effects of different levels of pollution. The system represents a simple tool for risk assessment of the harmful impact of contaminants by providing a clear indication of the degree of stress syndrome induced by pollutants in mussels.

Acute effects of cadmium on liver phase I and phase II enzymes and metallothionein accumulation on sea bream Sparus aurata

This research was designed to study Sparus aurata (sea bream) biotransformation and detoxification responses to acute exposure to cadmium (Cd). Sexually immature gilthead sea bream were treated by intraperitoneal injection of Cd chloride (200 microg kg(-1)) for 6, 12, 24 and 48 h. Cd accumulation was quantified in sea bream liver by graphite furnace atomic absorption spectroscopy after the various exposure periods. The following biological responses were measured: (1) ethoxyresorufin-O-deethylase (EROD) activity as phase I biotransformation parameter, (2) liver glutathione-S-transferase (GST) activity as a phase II conjugation enzyme and metallothionein (MT) content as specific response to Cd contamination. Cd bioaccumulation in the liver resulted in an increasing uptake up to 10.3 microg g(-1) wet weight after 48 h of exposure. EROD showed a significant activation only after 6 h exposure and a return to control levels after 12 h. GST revealed significant activation starting from 12 h exposure. MT accumulation in liver showed the same behavior as GST activation.

Assessment of heavy metal contamination using real-time PCR analysis of mussel metallothionein mt10 and mt20 expression: a validation along the Tunisian coast

In mussel Mytilus galloprovincialis tissues, metallothionein belongs to two different gene classes, mt10 and mt20, showing differential expression at both basal conditions and under heavy metal challenge. In this study, a new more highly sensitive technique, expression analysis of mt10 and mt20 mRNA levels by quantitative reverse transcription polymerase chain reaction, was used to assess the effects of heavy metal contamination in the digestive glands of mussels caged along the Tunisian coast. To validate the new assay, total metallothionein protein, amount of heavy metals (zinc, copper, cadmium), and a biomarker of oxidative stress such as malondialdehyde content, were assessed in the same tissues. At the investigated sites, the molecular assay showed variations of mt20 relative gene expression levels within one or two orders of magnitude, with maximum values at two sites severely polluted with cadmium, Mahres (100-fold) and Menzel Jemile (165-fold). Changes in mt10 expression were recorded at all sites where copper had significantly accumulated, although fold induction levels were less pronounced than those of mt20. In this paper, gene expression data are discussed in relation to the studied biomarkers, demonstrating that the molecular technique based on the differential expression of mt10 and mt20 genes represents (i) a useful and robust tool for studying and monitoring heavy metal pollution under field conditions, and (ii) an improvement in the application of metallothionein as a biomarker of response to exposure to heavy metals in marine mussels.

Oxidative DNA damage levels and catalase activity in the clam Ruditapes decussatus as pollution biomarkers of Tunisian marine environment

Levels of the oxidative DNA damage 7, 8-dihydro-8-oxo-2'-deoxyguanosine (8-oxodG) and catalase (CAT) activity were measured in the digestive gland and gills of clams Ruditapes decussatus, related to the presence of pollutants along Tunisian marine environment. Increased levels of CAT were observed in tissues of clams from all the sites studied, compared to control values, and elevated 8-oxodG levels were observed at specific sites. Results obtained in this work indicate that the measurement of 8-oxodG levels and CAT activity in tissues of R. decussatus is promising in pollution monitoring studies of the Tunisian marine environment.