Organochlorine pollutant levels in Mediterranean monk seals from the western Mediterranean and the Sahara coast

Blubber samples from 31 Mediterranean monk seals from the Sahara coast (Atlantic ocean) and from 2 individuals from the northern coast of Africa (western Mediterranean) were analysed for DDTs and PCBs. Seals from both regions carried qualitatively similar pollutant profiles, although levels were significantly higher in the individuals from the western Mediterranean than in those from the Sahara coast. Western Mediterranean seals presented higher relative abundance of recalcitrant PCB congeners in relation to those labile. This was associated with higher levels of enzyme induction in Mediterranean individuals, and therefore of their metabolic capacity, than in seals from the Sahara coast. Effects of organochlorine pollution in the Sahara coast population are considered to be negligible. Conversely, organochlorine levels detected in the single western Mediterranean monk seal male analysed were higher than thresholds commonly associated with immune depression and reproductive impairment in other pinnipeds. Given the extremely low number of monk seals surviving in the Mediterranean today, this possibility is a matter of serious concern.