Heavy metals and organochlorine compounds in blood of a stranded Risso’s dolphins from Northern Adriatic Sea, Italy.

Pollutants play an important role in the crisis populations in dolphins. This long living mammals tend to accumulate contaminants because of the high lipidic composition of their tissues, their rank in the food chain and food preferences. Assessing pollutants concentrations can help to investigate the possible effect on the immune system and on the reproductive cycles of endangered species. Risso’s dolphin Grampus griseus is rarely present in shallow waters like Adriatic sea, where reprents about 4% of strandings (Mazzariol et al. 2007). Present work reports about the heavy metals and organochlorine compounds (organochlorine pesticides and PCBs) content in blood of a Risso’s dolphin stranded in summer 2007 in Northern Adriatic Sea. Samples were collected during rehabilitation cares and analysed with ICP-AOS and GC/MS techniques. Metals concentration found are close to those observed in a stranded Risso’s dolphin from Israel by Shohan et al. (2002) and are equal to 7.31 μg/ml for Hg, 0.05 μg/ml for Cd, 0.13 μg/ml for Pb and 0,40 for μg/ml for As. Interestingly Cu and Zn are below the limit of detection of the method. For organochlorine compounds, only some of the investigated organohalogen were detected: HCB (0.77 ng/ml), HCH (1.45 ng/ml), DDT (4.32 ng/ml). Concerning PCBs, congeners 118, 128, 157, 158, 167, 177, 180, 183, 192 and 201 were detected, always at the ng/ml level. Low levels of organochlorine compounds observed can be due to the poor conditions of the animal, who was starved and didn’t eat. This caused a loss of adipose tissue, a certain mobilisation of contaminants and their rapid excretion. The same consideration is valid for heavy metals. Actually there is a lack of comparing data and their interpretation can be speculative. Anyway, the combination of blood and tissues analysis will give more information and make these evaluation more easy.