ECOLOGICAL AND BIOLOGICAL FACTORS CONTROLLING THE CONCENTRATIONS OF TRACE-ELEMENTS (AS, CD, CN, HG, SE, ZN) IN DELPHINIDS GLOBICEPHALA-MELAS FROM THE NORTH-ATLANTIC OCEAN

Trace elements (As, Cd, Cu, Hg, Se and Zn) were determined in liver and kidney of pilot whales Globicephala melas Traill, 1809 collected from 7 schools caught at different seasons around the Faroe Islands. These and other biological data at our disposal enabled us to confirm and to define more accurately the relations shown previously between age, sex and trace element concentrations in marine mammals. The most striking features were: (1) the elevated levels of Cd and Hg in pilot whales compared to other marine mammals and to minimum adverse-effect levels established for humans; (2) the biocumulative behaviour of Cd and Hg; (3) the high correlations between Hg and Se, predominantly influenced by age; and (4) the high correlations between Cd and Zn, the levels of which appear to be mainly dependent on the school to which the specimens belong. This last may be tentatively attributed to the fact that the schools sampled correspond to different sub-populations with different genetic characteristics. The apparent metal tolerance of pilot whales and the health consequences to consumers of flesh of marine mammals are discussed.