Persistent contaminants in dolphins: An indication of chemical pollution in the Mediterranean Sea

Concentrations of metals (mercury and methylmercury, selenium. cadmium, lead), chlorinated pesticides and polychlorinated byphenyls (PCB) have been determined in tissues and organs of Stenella coeruleoalba dolphins beached along the Adriatic and Ionian coasts of Apulia (Southern Italy). The results obtained confirm that in Mediterranean dolphins the accumulation of contaminants is higher than in similar species living in the Atlantic. Therefore cetaceans can be considered ''organisms indicating pollution''. Accumulation is influenced by factors such as diet, age and sex, Reproduction plays a fundamental role in the elimination of toxic compounds in females. Correlation between contamination and death has not been found; however it is clear that pollutants at sub-lethal doses have neuro-toxic effects, increase stress and alter immune defences, leaving the organism at a greater risk from disease.