The incidence of polychlorinated biphenyl and organochlorine pesticide residues in the eggs of the cormorant Phalacrocorax carbo sinensis/ : an evaluation of the situation in four Greek wetlands of international importance

This study contributed to identifying the current levels of organochlorine pollutants in four Greek wetlands of international importance the Evros and Axios Deltas, and Kerkini and Prespa Lakes., using the cormorant Phalacrocorax carbo sinensis as a suitable bioindicator in a region where such information is scarce. Residue levels of eight polychlorinated biphenyl PCB. congeners and 13 organochlorine pesticide OC. compounds were measured in cormorant eggs. Most PCBs and OCs except dieldrin and endrin. were found in at least some of the study areas. Median concentrations of five PCBs IUPAC 8, 20, 52, 138, 180. and of six OCs a-BHC, b-BHC, lindane, heptachlor, 4,49-DDE and 4,49-DDT. differed significantly among the areas. The median totals of the PCBs were highly significant among the areas, being unexpectedly highest in Prespa Lake 68.43 ppb., despite its remoteness, and lowest in Evros Delta samples 12.17 ppb.. Aldrin that was found in samples from Evros, Axios and Prespa probably accumulated in wintering grounds. In all of the areas, the relative proportions of a-BHC and 2,49-DDD were the highest of all OCs. Fingerprint and cluster analyses illustrated overall differences in the PCB patterns, being greatest between the deltas than between the lakes, but, inversely, for OCs the differences were smaller in the deltas. Differences were attributed to large variations in the cormorants’ diet between areas and different regimes of pollutant management in the two types of wetland. Correlations of pollutants varied considerably among areas and