冬季长江口及其邻近水域的浮游植物

Phytoplankton in Changjiang Estuary and adjacent waters in winter

根据2006年2月19日～3月5日在长江口及其邻近水域进行的大面调查所获样品，报道了该水域浮游植物的群落特征。此次调查共发现浮游植物5门56属116种（包括未定名17种）。调查水域浮游植物群落以硅藻为主，其次为甲藻，此外还有少量的金藻、蓝藻和绿藻。主要优势种为具槽帕拉藻Paralia sulcata、离心列海链藻Thalassiosira excentricus、圆海链藻Thalassiosi rarotula和辐射圆筛藻Coscinodiscus radiatus。调查区浮游植物的细胞丰度介于（111．11～2315．56）×10^4／m^3，平均值为914．87 ×10^4／m^3。近岸和调查区的东北部表层浮游植物丰度较高，其他区域表层丰度较低。浮游植物的垂直分布特征是细胞丰度的最大值出现在表层以下，随深度的增加，浮游植物的细胞丰度先上升后下降。多样性分析表明，香农-威纳多样性指数和Pielou均匀度指数在近岸口门处较高，离岸水域较低。

The water samples of phytoplankton were selected from the grid survey around the Changjiang Estuary and adjacent waters from 19^th Feb. to 5Lh Mar. 2006. The phytoplankton commuinity and its structure were reported in this paper. A total of 116 taxa （including 17 uncertain species） belonging to 56 genera of 5 phyla were identified. The main phytoplankton group was diatom and the second was dinoflagellate. There were also a few species belonging to Chrysophyceae, Chlorophyceae and Cyanophyeeae. The dominant species were Paralia sulcata, Thalassiosira excentricus, Thalassiosira rotula and Coscinodiscus radiatus. The cell abundance of phytoplankton ranged from 111.11 to 2315.56×10^4/m^3 and the average was 914.87 ×10^4/m^3. The average cell abundance of phytoplankton in surface water was relatively high in the inshore area and northeast in the survey area. The vertical distribution of phytoplankton showed that the maximum cell abundance was found in subsurface water, and along with the increase of the depth cell abundance firstly was increased then decreased. According to the study on the diversity of phytoplankton community, the Shannon-Weaver diversity index and Pielou evenness index were high in the river mouth and low offshore.