TI: Ecological variability in Antarctic coastal environments: past and present

AU: Berkman,-P.A.

SO: Antarctic-Communities:-Species,-Structure-and-Survival Battaglia,-B.; Valencia,-J.; Walton,-D.W.H.-(eds.) Cambridge-University-Press-UK 1997 pp. 349-357

LA: English

AB: Holocene macrofossils in emerged beaches can be used to interpret environmental variability in the coastal zone around Antarctica which has been directly impacted by ice-sheet advance and retreat during the last 10 000 years. Radiocarbon dating was used to determine fossil ages based on reservoir corrections derived from the average pre-bomb super(14)C-ages of different Antarctic species: seals (1424 plus or minus 200 years), penguins (1130 plus or minus 134 years) and molluscs (1300 plus or minus 100 years). In the modern marine environment, the oxygen isotope composition of mollusc shells varies seasonally and across nearshore depth gradients associated with glacial meltwater input. In the fossil record, scallop shells in emerged beaches along the Victoria Land coast have oxygen isotope ratios that reflect a relatively long warm period around 6000 years before present (y BP) and a brief cold period 500 y BP which may be associated with the Little Ice Age. The persistence of scallop and Adelie penguin populations along the Victoria Land coast since the middle Holocene, as well as their localized migrations during this period, can be attributed unambiguously to natural phenomena in the absence of human activities. Viewed in a circumpolar perspective, these long-term dynamics of coastal populations can be used to interpret the transitory nature of anthropogenic impacts in the Antarctic marine ecosystem. Coordinated among nations, this interdisciplinary research in Antarctic coastal areas will enhance our understanding of the Earth's climate system.