Organochlorine insecticide and polychlorinated biphenyl residues in eggs of coastal birds from the eastern Cape, South Africa

Abstract

The concentrations of organochlorine insecticide and PCB residues were determined in eggs of jackass penguins Spheniscus demersus, Cape gannets Sula capensis, Cape cormorants Phalacrocorax capensis, white-breasted cormorants P. carbo, African black oystercatchers Haematopus moquini, roseate terns Sterna dougallii, kelp gulls Larus dominicanus, and grey-headed gulls Larus cirrocephalus. These species were selected as representatives of exclusively marine, mixed marine-estuarine-freshwater, intertidal-marine, scavenging-marine-estuarine-intertidal and scavenging-estuarine-freshwater habitats. All the eggs were positive for DDE with residue levels highest in the mixed scavenging species and lowest in the marine species. Similar trends were noted for dieldrin, but the levels were low or absent in most marine species. The eggs of most species exhibited residue levels of PCBs and the trends in terms of feeding habitats were similar to those noted with DDE. Based on a comparison with studies elsewhere, none of the organochlorine pesticide or PCB residue levels appear high enough to cause reproductive impairment or egg shell thinning.