The pack ice region surrounding Antarctica contains at least fifty percent of the world's population of seals, comprising about eighty percent of the world's total pinniped biomass. As a group, these seals are among the dominant top predators in Southern Ocean ecosystems, and the fluctuation in their abundance, growth patterns, life histories, and behavior provide a potential source of information about environmental variability integrated over a wide range of spatial and temporal scales. This proposal was developed as part of the international Antarctic Pack Ice Seals (APIS) program, which is aimed to better understand the ecological relationships between the distribution of pack ice seals and their environment. During January-February, 2000, a research cruise through the pack ice zone of the eastern Ross Sea and western Amundsen Sea will be conducted to survey and sample along six transects perpendicular to the continental shelf. Each of these transects will pass through five environmental sampling strata: continental shelf zone, Antarctic slope front, pelagic zone, the ice edge front, and the open water outside the pack ice zone. All zones but open water will be ice-covered to some degree. This component of the APIS program will focus on the variation of two sets of genetic loci to determine species-wide genetic variability of pack-ice seals. One set is the major histocompatibility complex, which is involved in immune system responses while the other is the microsatellite locus which does not code for a gene product. The dual approach will enable the team to assess quantify the amount of immunologically-relevant genetic variation in a species with the background of overall genetic variation. This study will complement others on the health status of Antarctic ice seals. Better insight into the interplay among pack ice seals and biological and physical features of Antarctic marine ecosystems will allow for a better prediction of fluctuation in seal population in the context of environmental change.
