2008年夏季白令海陆架区微微型浮游植物分布及环境相关性分析

Distribution of picophytoplankton and environmental correlation analysis in Bering Sea shelf during the summer of 2008

利用2008年夏季我国第3次北极科学考察资料,基于流式细胞技术,对白令海北部陆架区的微微型浮游植物丰度、细胞大小（碳含量）、色素浓度的分布特征进行了分析,并对该类群的环境适应性进行了研究。结果表明,微微型浮游植物中仅含聚球藻和真核藻,其丰度范围分别为0.14×106~2.69×106和0.23×106-12.49×106个/dm3。聚球藻的叶绿素a和藻红蛋白含量、微微型真核藻的叶绿素a含量与类群丰度以及微微型真核藻的类胡萝卜素含量与细胞大小间均存在同向变化趋势。两类藻偏向于喜温嗜淡型,更适合在寡营养环境中保持较高的丰度,但能在高营养盐浓度下形成相对较高的碳含量。越接近陆地,细胞越小,丰度越大,碳含量及FL2/FL3越低;所处层位越深、纬度越高,则细胞越大,碳含量及FL2/FL3越高。北极气温升高和径流量的增加有利于陆架区微微型浮游植物类群丰度的增加。

The abundance,cell size（cellular carbon content）,and cellular pigments of picophytoplankton on the shelf area of the north Bearing Sea（61°29′~64°21′N,168°00′~174°32′W） were analyzed by flow cytometry（FCM）.A statistical analysis was used to study the response of the picophytoplankton to environmental changes.Synechococcus and picoeukaryotes were the only type of the picophytoplankton community;and their respective cell abundance was 0.01×106~2.69×106 and 0.47×106~13.20×106 cells/dm3.The chlorophyll a,phycoerythrin,and the cell size（cellular carbon content） had the same changing trend with the change of environmental factors.Comparatively,the chlorophylls a and the cell abundance,and the carotenoids and the cell size（cellular carbon content） of the picoeukaryotes had the same changing trends,respectively.Both salinity and nutrients had significant influence on the cellular carbon content and the ratio of carotinoids to chlorophylls a of picoeukaryotes.High nutrient concentration was prone to induce high ratio of cellular carbon content to chlorophylls a.Both synechococcus and picoeukaryotes preferred relatively high temperature and low salinity;and were easily to form high cell abundance in oligotrophic water,whereas in seawaters with relatively high nutrient concentration were prone to form cells with high cellular carbon content.The cell abundance of picoeukaryotes decreased intensely when the nitrogen-phosphorus ratio greater than 7.The cell abundance was relatively high,whereas the cell size（cellular carbon content） and the phycoerythrin-chlorophyll a ratio were relatively small.Comparatively,the cell size（cellular carbon content） and the phycoerythrin-chlorophyll a ratio were relatively large and the cell abundance was relatively low when the picophytoplankton was at relatively deep water layers and high latitudes.The ascending of the water temperature and the increase of the inflows of freshwater from the continent can increase both the abundance and the variety of picophytoplankton on the continental shelf of the north Bering Sea.