Impact on the biological diversity in polar lakes affected by global environmental changes.

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To know the influences to the biological features in the polar lakes by the global environmental changes during 2002-2005, water sample, lake bottom vegetation, sediment core samples and environmental data given on the lake research project were investigated.Based on the water temperature, salinity, dissolved oxygen and so on, lakes located at the adjacent area of Syowa Station, East Antarctica were categorized to four types (Type 1-4). Type 1 : melt water from glacier flows directly into lakes, Type 2 : melt water flows into lakes through stream, Type 3 : melt water from snow beds flows into lakes and Type 4 : lake water originates from sea water. These lake types also correspond with the biological features. Organic component such as total organic carbon (TOC), total nitrogen (TN), hydrocarbon, fatty acids and sterols in aquatic moss vegetation and sediment core from lake bottoms from the Syowa Station area were studied to clarify their features in relation to paleo-environmental change.Aquatic mosses (Bryum, Leptobryum) have been recently known to form a unique structure called "moss pillar", in association with algae including cyanobacteria. We have studied a moss pillar from the lake in Skarvsnes by fatty acid analysis. Neutral lipid fatty acid (NLFA) profiles were largely groped exterior and interior parts and locally associated with different bacterial groups in the lower-interior and lower-exterior parts. Dry weight, carbon, nitrogen and chlorophyll distributions in the moss pillar took heterogeneous pattern, but they were largely centered at apical parts. It is suggested that growth of moss pillar occurred extensively at the apical part. The age was estimated ca.250 years at ca.20 cm below the apical top by the AMS method.