Perfluorinated and other persistent halogenated organic compounds in European shag (Phalacrocorax aristotelis) and common eider (Somateria mollissima) from Norway: a suburban to remote pollutant gradient.

Samples of two marine bird species, European shag (Phalacrocorax aristotelis) and common eider (Somateria mollissima) sampled at a remote coastal site in Norway were analysed for POPs and PFCs. Additionally samples of common eider were analysed from two other locations in Norway, representing a gradient from "densely populated" to "remote". The variety, concentration and distribution of lipophilic POPs in comparison to PFCs were investigated. PCBs were the dominating group of contaminants in the analysed egg samples. Shag eggs had median sum PCBs levels of 4,580 ng/g l.w. in 2004. Six different PBDE congeners could be detected in the shag eggs. BDE 47 and 100 were the main contributors with 24 and 27 ng/g l.w. respectively, sum PBDEs was 90 ng/g l.w. Relatively high concentrations of chlordanes were found with a total sum of 903 ng/g l.w. Of other OCs, toxaphene 26 and 52 together (sum 657 ng/g l.w.) and HCB (165 ng/g l.w.) were contributing majorly to the egg burden. Sum HCHs were low; only 54 ng/g l.w. PFOS was the main PFC in egg, plasma and liver samples. Similar median levels of 29, 32 and 27 ng/g w.w. were observed. PFOSA, PFH x S, and PFDcA were observed additionally in all shag samples at minor concentrations with the exception of elevated levels observed in liver for PFOSA and PFDcA with median levels of 7.6 and 7.9 ng/g w.w., respectively. In common eider eggs, the POP concentrations decreased up to 1/8th along the sampled spatial gradient from suburban to remote. Of the 9 detected PFCs, PFOS dominated all samples by one order of magnitude, followed by PFOA. Sum PFC concentrations were twice as high at the two fjord sites compared to the remote site. Shorter chained PFCAs like PFOA and PFNA could be detected in the eider eggs whilst being absent in shag eggs.

Metal dynamics in an Antarctic food chain.

The concentrations of copper, zinc, cadmium, selenium and mercury were determined in eggs, muscle, liver, kidney and stomach content of nestilings and adults of the Antarctic petrel, Thalassoica antarctica, and its predator, the south polar skua, Chataracta maccormicki, from Svarthamaren, Dronning Maud Land, Antarctica. The dominant food of the petrels is krill, Euphausia superba. The results show relatively high levels of cadmium in krill, which is assumed to be the main reason for the high levels of cadmium in petrels and skuas. Cadmium is almost absent in eggs, but accumulates very rapidly with age in nestlings. The copper concentrations in livers of nestling petrels reach very high levels during growth. This may be seen in connection with physiological development processes. Mercury seems to be accumulated with age and between trophic levels. Among the nestlings, the mercury levels decrease with increasing age, which may be accomplished by the excretion of mercury through the growth of feathers and as a dilution effect during growth. Selenium and mercury are inversely correlated in nestlings. The levels of zinc were similar for different nestling stages and between nestlings and adults in skuas and petrels.

Exploitation of inland-breeding Antarctic petrels by south polar skuas.

During the austral summer of 1996/1997 we studied south polar skuas at Svarthamaren, Dronning Maud Land, Antarctica, where the world's largest known colony of Antarctic petrels is found. Our censuses suggested approximately 250 full-grown skuas and 140,000 breeding pairs of petrels were present. During their breeding season, skuas did not visit the open sea at least 200 km from the site; they relied entirely on prey caught and scavenged from the petrel colony. Because the site is so isolated, we asked whether the prey (petrels) had swamped the predators (skuas), or whether there was evidence that predator numbers were limited by the size of the prey population. Particularly at the end of the petrel incubation period, we found a close correspondence between the energy required by adult skuas and their chicks, ascertained from time budget studies, and the rate at which petrel eggs disappeared from the colony. This suggests that, in this closed system, the predator population was limited by the prey population, and that predator swamping was not an advantage that petrels gained by nesting in this remote location.