2006年秋季东海陆架浮游植物群集

Phytoplankton assemblages on the continental shelf of East China Sea in autumn 2006

根据2006年11月19日—12月24日在东海陆架海域(24.0°—32.0°N,120.0°—127.0°E)进行的综合采样调查,对调查海域浮游植物的群集特征进行了研究.本次调查共发现浮游植物4门64属145种(包括未定名种),其中硅藻是该调查海区浮游植物的主要功能群,其次为甲藻.主要的优势种为菱形海线藻、圆海链藻、丹麦细柱藻、斯氏几内亚藻、尖刺伪菱形藻和铁氏束毛藻等.浮游植物细胞丰度为0.09～5.11cells.ml-1,平均值为4.92cells.ml-1,秋季东海陆架浮游植物细胞丰度的平面分布主要由浮游硅藻刻画,其高值出现在调查区的北、东部离岸海域,细胞丰度大于30cells.ml-1.浮游植物及硅藻和甲藻的细胞丰度垂直变化趋势基本上都是随着水深增加,丰度逐渐减小.各个断面细胞丰度密集区主要集中在表层,个别站位的中层和底层也出现浮游植物密集区.调查区浮游植物的多样性指数平均值为2.80,其高值位于调查区东北和东南部,物种均匀度指数平均值为0.81,其高值位于调查区中部,生物多样性的分布与细胞丰度的分布一致.从Pearson相关性指数来看,亚硝酸盐、溶解态有机氮(DON)和温度显著影响调查区浮游植物的生长.

Based on the survey from November 19 to December 24, 2006, the species composition, assemblage structure, and cell abundance of phytoplankton on the continental shelf of East China Sea （24.0°-32.0°N,120.0°-127.0°E） were studied. The phytoplankton flora in the survey area included 145 taxa, belonging to 64 genera of 4 classes （including uncertain species）. Bacillariophyta was the dominant functional group, followed by Pyrrophyta. The dominant species in turn were Thalassionema nitzschioides, Thalassiosira rotala, Leptocylindrus darricus, Guinardia striata, Pseudo-nitzschia pungens, and Trichodesmium thiebautii. The cell abundance of the phytoplankton ranged from 0.09 to 35. 11cells - ml^-1 , with an average of 4. 92 cells · ml^-1. In the autumn, Bacillariophyta abundance discriminated the surface pattern of the phytoplankton, and the higher abundance area was located at the northeast part of offshore regions, with the cell abundance reached 30 cells · ml^-1. On the whole, the cell abundance of Bacillariophyta and Pyrrophyta was concentrated in surface water, and it reduced rapidly from surface layer down to the bottom. According to the section distribution, the phytoplankton mainly concentrated in surface water, and also, in the middle and bottom layers for some stations. The average of Shannon-Wiener indices of phytoplankton assemblage was 2. 80, with the higher values occurred in the northeast and southeast of the survey area. The average of Pielou＇ s evenness of phytoplankton assemblage was 0. 81, and the higher value was located at the middle of the survey area. The surface horizontal distribution of Shannon-Wiener indices was coincided with that of phytoplankton cell abundance. According to the Pearson correlation analysis, the factors that significantly affected the growth of the phytoplankton were nitrite, dissolved organic nitrogen （DON）, and temperature.