FLUCTUATING CONCENTRATIONS OF ORGANOCHLORINE POLLUTANTS DURING A BREEDING-SEASON IN 2 ANTARCTIC SEABIRDS - ADELIE PENGUIN AND SOUTHERN FULMAR

During the reproductive cycle significant fluctuations of concentratio ns of organochlorine pollutants were detected in blood and uropygial o il from Adelie penguins (Pygoscelis adeliae) and southern fulmars (Ful marus glacialoides) from Hop Island, Antarctica. In the Adelie penguin , concentrations of polychlorinated biphenyls (PCBs) and dieldrin were significantly higher at the moment of egg laying, while hexachloroben zene (HCB) and 2,2-bis(p-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE) concentrations peaked at the creche stage. Subcutaneous fat is the ma in pool for HCB and p,p'-DDE, while PCBs and dieldrin are also stored in the pectoral muscle. It is hypothesized that the observed differenc es in seasonal fluctuations in organochlorine levels are related to ut ilization of different storage pools by the Adelie penguins at differe nt moments in the breeding season. In the southern fulmar the fluctuat ions in concentrations of HCB and p,p'-DDE can be related to changes i n body mass. However, concentrations of PCBs and dieldrin did not vary significantly during the season. It seems that the two groups of comp ounds are governed more or less independently in the southern fulmar a s well. Age-dependent accumulation of most organochlorines studied rea ched a steady state before the age at which both species start to bree d. This allows monitoring of individual birds to analyze changes in co ncentrations of organochlorine pollutants in the ecosystem, without ha ving to correct for age differences. Differences in levels of organoch lorine pollutants between the Adelie penguin and southern fulmar were probably the result of differences in feeding ecology.