Concentrations and patterns of organochlorine pesticides and PCBs in Mediterranean monk seals (Monachus monachus) from Western Sahara and Greece

Blubber from Mediterranean monk seals (Monachus monachus) from the Western Sahara coast (Atlantic), sampled during 1996– 1999, and from theGreek coast (Mediterranean), sampled during 1995–1999,was analyzed for organochlorine pollutants (OCs). In both populations, no significant differencewas found between sexes. In theAtlantic population, mature females presented greater percentages of higher chlorinated PCB (polychlorinated biphenyl) congeners in relation to total PCBs (sum of 25 congeners) than pups, indicating a differential transfer of PCB congeners through lactation. In the Mediterranean, the reduced sample size of adult individuals precluded proper statistical investigation of age-related variation. Significant differences in concentrations and pollutant patterns were found between populations. Thus, Mediterranean individuals presented significantly higher levels of HCB (hexachlorobenzene), tPCB, and DDTs (dichlorodiphenyltrichloroethane) concentrations andDDE/tDDTand tDDT/tPCB ratios than their counterparts fromthe Atlantic. Moreover, the relative proportion of different congeners in relation to the total PCB load (congener/tPCB) was also different between the two areas. The 100⁎tDDT/tPCB ratio in Atlantic seals was 38.46, which indicates a predominance of industrial inputs over those associated with agriculture. Conversely, in the Mediterranean seal population, the 100⁎tDDT/tPCB ratio was 177.1, denoting a proportionally higher contribution of pollutants of agricultural origin.