The McMurdoDryValleysofAntarcticaare a unique environment characterized by extreme lows in temperature and precipitation, which supports a low diversity microbial and multicellular fauna and flora. Terrestrial biomass...The McMurdoDryValleysofAntarcticaare a unique environment characterized by extreme lows in temperature and precipitation, which supports a low diversity microbial and multicellular fauna and flora. Terrestrial biomass is largely limited to soil microbes and mosses, while perennially ice-covered lakes host aerobic and anaerobic microbial communities, algae, and a low diversity eukaryotic fauna. This study provides a scanning electron microscope survey of the distribution of siliceous-walled algae in the water columns and surface sediments of fourTaylorValleylakes. No patterns of distribution of algae, chrysophyte cysts and diatoms, are detected, suggesting that cores taken from perennially ice-covered lakes contain basin-wide records, rather than records specific to the lake depth or other lake-specific criteria. Since Taylor Valley lakes became perennially ice-covered, shifts in diatom assemblages in cores are more likely to record changes to sediment and microfossil transport, e.g. the dominance of eolian vs. stream input, rather than other ecological conditions. Basin-wide records are episodically overprinted by lake-specific events, as demonstrated by a marked increase of the stream diatom genus Hantzschia during a period of increased stream flow into East Lake Bonney.展开更多
文摘The McMurdoDryValleysofAntarcticaare a unique environment characterized by extreme lows in temperature and precipitation, which supports a low diversity microbial and multicellular fauna and flora. Terrestrial biomass is largely limited to soil microbes and mosses, while perennially ice-covered lakes host aerobic and anaerobic microbial communities, algae, and a low diversity eukaryotic fauna. This study provides a scanning electron microscope survey of the distribution of siliceous-walled algae in the water columns and surface sediments of fourTaylorValleylakes. No patterns of distribution of algae, chrysophyte cysts and diatoms, are detected, suggesting that cores taken from perennially ice-covered lakes contain basin-wide records, rather than records specific to the lake depth or other lake-specific criteria. Since Taylor Valley lakes became perennially ice-covered, shifts in diatom assemblages in cores are more likely to record changes to sediment and microfossil transport, e.g. the dominance of eolian vs. stream input, rather than other ecological conditions. Basin-wide records are episodically overprinted by lake-specific events, as demonstrated by a marked increase of the stream diatom genus Hantzschia during a period of increased stream flow into East Lake Bonney.
