Distribution of mercury in the organs and tissues of five toothed-whale species of the Mediterranean

Mercury levels were determined in the tissues and organs (lung, liver, kidney, skin, muscle, bone) of five toothed-whales stranded along the Corsican coast between November 1993 and February 1996. The species taken into consideration were the bottlenose dolphin Tursiops truncatus, the common dolphin Delphinus delphis, the striped dolphin Stenella coeruleoalba, the pilot whale Globicephala melas and the Risso's dolphin Grampus griseus. The variation in mercury levels between the different tissues and organs (lung, liver, kidney, skin, muscle, bone) of the cetacean species are discussed as regards storage, biotransformation and elimination. In all cases, the liver appears to be the preferential organ for mercury accumulation (with concentrations as high as 4250 microg Hg/g dw and 3298 microg Hg/g in the livers of Tursiops truncatus and Grampus griseus, respectively). The kidney and lung are the next organs in terms of mercury uptake followed by the muscle, bone and skin. The stomach contents of Grampus griseus and D. delphis were determined and consisted of cephalopods for Grampus griseus, and of sardines Sardina pilchardus and mackerels Trachurus sp. for D. delphis. Cephalopods had higher mercury concentrations (25.4 microg Hg/g dw) than fish (ca 1 microg Hg/g). These contents represent only one meal and mercury levels found in livers may integrate mercury uptake having occurred during the whole life span of animals.