Phytoplankton blooms under dim and cold conditions in freshwater lakes of East Antarctica

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• 作者：Yukiko Tanabe ; Sakae Kudoh ; Satoshi Imura and Mitsuo Fukuchi
• 刊名：Polar Biology
• 出版年：2008
• 出版时间：January, 2008
• 年：2008
• 卷：31
• 期：2
• 页码：199-208
• 全文大小：590.8 KB

文摘

The seasonal variations of limnological (water temperature, light availability, turbidity, and chlorophyll a concentration) parameters were recorded continuously from January 2004 to February 2005 at two freshwater lakes: Oyako-ike and Hotoke-ike, S?ya Coast, East Antarctica. Water was in a liquid phase throughout the year, with temperatures ranging from 0 to 10¡ãC. The maximum photosynthetically active radiation in Lake Oyako-ike was 23.16 mol mW22;2 dayW22;1 (at 3.8 m) and Hotoke-ike was 53.01 mol mW22;2 dayW22;1 (at 2.2 m) in summer, and chlorophyll a concentration ranged from ca. 0.5 to 2.5 μg LW22;1 (Oyako-ike) and from ca. 0.1 to 0.8 μg LW22;1 (Hotoke-ike) during the study period. Increase in chlorophyll a fluorescence occurred under dim-light conditions when the lakes were covered with ice in spring and autumn, but the signals were minimum in ice-free summer in both the lakes. During spring and summer, as a result of decreasing snow cover, the chlorophyll a concentration similarly decreased when PAR was relatively high, following periods of heavy winds. The autumnal and spring increase occurred under different PAR levels (ca. 20-fold and 90-fold stronger, respectively, in autumn in both the lakes). Differences in the autumn and spring increases suggest that the spring algal community is more shade-adapted than the autumn algal community. Antarctic phytoplankton appears especially adapted to low-light levels and inhibited by strong light regimes.