With the onset of winter, polar marine microalgae would have faced total darkness for aperiod of up to 6 months. A natural autumn community of Arctic sea ice microalgae was collected for dark survival experiments from...With the onset of winter, polar marine microalgae would have faced total darkness for aperiod of up to 6 months. A natural autumn community of Arctic sea ice microalgae was collected for dark survival experiments from the Greenland Sea during the ARKTIS-XI/2 Expedition of RV Po-larstem in October 1995. After a dark period of 161 days, species dominance in the algal assemblage have changed from initially pennate diatoms to small phytoflagellates (<20 μm). Over the entire dark period, the mean algal growth rate was - 0.01 d-1. Nearly all diatom species had negative growth rates, while phytoflagellate abundance increased. Resting spore formation during the dark period was observed in less than 4.5% of all cells and only for dinoflagellates and the diatom Chaetoceros spp. We assume that facultative heterotrophy and energy storage are the main processes enabling survival during the dark Arctic winter. After an increase in light intensity, microalgal cells reacted with fast growth within days. Phytoflagellates had the highest growth rate, followed by Nitzschia frigida. Further investigations and experiments should focus on the mechanisms of dark survival (mixotrophy and energy storage) of polar marine microalgae.展开更多
基金This project was supported by the National Natural Science Foundation of China under contract No. 49906006.
文摘With the onset of winter, polar marine microalgae would have faced total darkness for aperiod of up to 6 months. A natural autumn community of Arctic sea ice microalgae was collected for dark survival experiments from the Greenland Sea during the ARKTIS-XI/2 Expedition of RV Po-larstem in October 1995. After a dark period of 161 days, species dominance in the algal assemblage have changed from initially pennate diatoms to small phytoflagellates (<20 μm). Over the entire dark period, the mean algal growth rate was - 0.01 d-1. Nearly all diatom species had negative growth rates, while phytoflagellate abundance increased. Resting spore formation during the dark period was observed in less than 4.5% of all cells and only for dinoflagellates and the diatom Chaetoceros spp. We assume that facultative heterotrophy and energy storage are the main processes enabling survival during the dark Arctic winter. After an increase in light intensity, microalgal cells reacted with fast growth within days. Phytoflagellates had the highest growth rate, followed by Nitzschia frigida. Further investigations and experiments should focus on the mechanisms of dark survival (mixotrophy and energy storage) of polar marine microalgae.
