ECOTOXICOLOGICAL EVALUATION OF CLAM HARVESTING AREAS

Since several ecotoxicological studies were performed in the Lagoon (since the 1980s) we will synthesise the main evidences from ecotoxicological indicators in the areas of clam harvesting. Three groups of bioindicators were defined (Fränzle, 2006): a) test organisms, used in toxicity bioassays which involve the deliberate exposure of test animals to contaminants or contaminated materials (Hahn, 2002); in an aquatic environment, the species is generally exposed in controlled conditions to an environmental sample containing mixtures of pollutants at unknown concentrations in order to verify possible toxic effects (Volpi Ghirardini and Pellegrini, 2001); b) accumulation indicators, which must dispose of a fairly high amount of strain resistance enabling them to incorporate for a considerable time, depending on the uptake-excretion ratio, potentially toxic substances without injury (Fränzle, 2006); c) reaction indicators, which respond (relatively) quickly and in an observable or measurable manner to physical or chemical stress; these indicators are generally known as biomarkers, which are biochemical, physiological or behavioural variations measured in a tissue, biological fluid or the whole organism (individual or population) evidencing exposure and/or effect to one or more contaminants (Depledge and Fossi, 1994). PREFAC