Monitoring of environmental pollutants in aquatic organisms: toxicological risk assessment

The research activity of the PhD project in Veterinary Science aimed at determining the presence of environmental pollutants in aquatic organisms to improve the current knowledge on animal biomonitoring and provide the toxicological risk assessment connected, concerning the link between pollution and human and animal health. Many industrial pollutants, especially micropollutants, have adverse effects at very low concentrations. It is therefore important to early detect the presence of these compounds directly or through particular molecular biomarkers found in living organism. As a matter of fact, the search of these substances in the natural environment, is not always easy as they are often present below the detection threshold. In aquatic ecosystems, the use of invertebrate species seems to be an appropriate way of monitoring the environmental quality, due to their general capacity to accumulate pollutants, either from sediments and surrounding water or from food sources. The research activity wes carried out on the following aquatic organisms: • The common octopus (Octopus vulgaris) is a mollusc belonging to the class Cephalopoda. It is considered a cosmopolitan species as its range extends from the eastern Atlantic to the Mediterranean Sea and at least to Senegal in Africa. Octopus vulgaris constitutes an important marine resource suitable for human consumption; however, they can represent a source of chemical contaminants intake particularly of heavy metals. The aims of this study were to determine (i) the levels of heavy metals (Pb, Cd and Hg) in the muscle and digestive gland of octopus caught from two different locations along Campania coast, as well as (ii) to estimate their weekly human intake derived from the ingestion of octopus. The analysis of 38 samples showed a higher concentration of Pb in the muscle of octopus in one of the sampling sites. Differences were observed between the two tissue types, with a higher level of Cd and Pb observed in the digestive gland compared to the muscle. Noteworthy, the consumption of O. vulgaris captured in some areas could increase Pb intake in heavy consumers of local fish products. The red swamp crayfish Procambarus clarkii (Girard, 1852), is an invasive freshwater species that originated in the north eastern Mexico and south-central United States. This species has been imported into Italy in the seventies, mainly for aquaculture purpose. Nowadays it is one of the most diffuse crayfish species in several European countries and is able to tolerate extreme and polluted environmentrs, accumulating heavy metals and toxins in its tissue, mainly in the hepatopancreas. The objectives of the present study were to evaluate the levels of Cd, Pb, Hg, As, Cr, Cu and Zn in muscle and in hepatopancreas of red swamp crayfish (Procambarus clarkii, Girard, 1852) collected from two different sites in Campania (Italy), Villa Literno and Sessa Aurunca, to provide data for both human health and the ecological risk assessment. The general evidence was that crayfishes from accumulated higher levels of metals (As, Cu, Zn and Cr) in the hepatopancreas than in the muscle. The results obtained in the current study showed low levels of Cd, Pb and Hg and largely below the MLR established by the European Commission for muscle from crustacean appendages. These results suggested a limited Cd, Pb and Hg contamination in the sampling sites and were indicative of low risk for human consumption. Our data showed that P. clarkii can be considered a good bioindicator for metal pollution in the study areas. • The warty crab (Eriphia verrucosa) is a bentonic species found in the Mediterranean Sea, the Black Sea, and the eastern Atlantic Ocean, from Brittany to Mauritania and the Azores. It is highly fecund and is reported to feed on bivalves, gastropods, and hermit crabs, or on mollusks and polychaetes. Eriphia verrucose shows a preferential uptake of pollutants from sediments. The aim of this study was to evaluate the levels of As, Cr and Pb and the content of six PAHs in edible muscle of warty crab from various coastal areas of Campania region. Results showed that PAHs and metals concentration in warty crab were always lower than the legal limits established by the European Commission. • The red seaweed, Kappaphycus alvarezii and Kappaphycus striatum are cultivated extensively as a source of carrageenan which have been used for decades in food applications and are generally regarded as safe. There are different studies in literature on the chemical-nutritional characteristics and the benefits of their use, but further studies are needed to identify any toxicological risks related to their use. Aims of this study were to evaluate the presence of chemical constituents and to quantify toxic and essential elements in two species of red seaweed Kappaphycus alvarezii and Kappaphycus striatum collected in Palau Bidong (Malaysia), in order to assess their potential use as additive in animal nutrition and the possible health risks related to animal consumption. The total amount of trace elements in K. alvarezii was almost double than in K. striatum, in agreement to the differences in ash percentages. On the whole, due to the low amount of protein on dry matter, red seaweeds K. alvarezii should be used in animals nutrtion under intensive production as mineral additive. • The edible mussel Mytilus galloprovincialis is among the most commonly used sentinel organisms for the monitoring of biological effects of various contaminants in the marine. Polychlorinated biphenyls (PCBs) are environmental pollutants of industrial origin that can contaminate food, mainly food of animal origin. Although production of PCBs has been banned in many countries since the 1980s, they are still present in the environment and are considered dangerous pollutants for human health. New analytical approaches are useful to monitor the presence of such contaminants in seafood products and in the environment. In this work, we evaluate changes in protein expression of Mytilus galloprovincialis (Lam.) experimentally exposed to a PCB mixture and identify chemically specific protein expression signatures by using a proteomic approach. In particular, we identify 21 proteins whose levels of expression are sensibly modified after 3 weeks of exposure. The present work shows that a proteomic approach can be a useful tool to study alterations of protein expression in mussels exposed to PCBs and represents a first step toward the development of screening protocols to be used for biomonitoring surveys of fishery products