Palaeolimnological evidence for marked Holocene environmental changes on Signy Island, Antarctica

Lake-sediment cores from Heywood and Sombre Lakes on Signy Island (South Or kney Islands), Antarctica, have yielded a conformable radiacarbon chronolog y far the Holocene and a high-resolution record of environmental change. Th e lakes share a common climate and geology but have distinct catchments. Th is provides an opportunity for using lake sediments to differentiate betwee n local, within lake/catchment, events and those at a regional scale. Analy ses of various biological and physical remains from the lakes suggest that both catchments have undergone considerable changes during the last 5700 ye ars. Macrofossils (moss and crustacean remains) are more abundant in the la te Holocene, being associated with a period of high sediment accumulation, which is related to diatom evidence for more nutrient-rich conditions at th e sites. This is interpreted as a response to a Holocene 'climate optimum' at c. 3800-1300 C-14 yr BP. The record is consistent with other lake, ice a nd ocean core studies, although the climate optimum appears to have persist ed for a longer period at Signy Island.