The community structure and biodiversity of phytoplankton were investigated, and water quality was assessed, in four reservoirs with different trophic states, in Hubei province, between 2006 and 2008. There were 215 species of phytoplankton in the four reservoirs, ranked in order of abundance: diatoms, Chlorella, and blue-green algae. Blue-green algae occurred primarily in the layer above transparency(SD), diatoms were most abundant in the layer between SD and 2SD, whereas other algae, including Scenedesmus and Trachelomonas, were mainly found in the layer above 2SD. Differences of phytoplankton density were observed among the layers such that the density in the surface layer was two to three times higher than in the bottom layer. The average density and biomass of phytoplankton were, respectively: 123.2×l04 cells·L-1 and 1.283 mg·L-1 in Jinshahe Reservoir; 258.6×l04cells·L ' and 3.335 mg·L-1 in Daoguanhe Reservoir; 210.5×l04cells·L-1 and 2.740 mg-L"1 in Xujiahe Reservoir; and 221.3×104cells·L-1 and 3.088 mg·L-1 in Taoyuanhe Reservoir. The distribution of phytoplankton biomass among layers was generally characterized as: SD>surface>2SD>3SD>bottom except for the Daoguanhe Reservoir, in which the order was surface>SD>2SD>3SD>bottom. There was a highly significant difference (P<0.01) in the Shannon-Wiener diversity index (H) and the Pielou evenness index (J) between Jinshahe Reservoir and the others, but there was no significant differences (P>0.05) among Daoguanhe, Taoyuanhe and Xujiahe reservoirs. A negative correlation was found between total nitrogen and phytoplankton biomass, while a positive correlation existed between total phosphorus and phytoplankton biomass. Variations of phytoplankton community structure were primarily attributed to the differences in the trophic levels of the four reservoirs.%2006-2008年对湖北境内4座水库的大型浮游植物群落结构和多样性进行周年研究.4座水库共鉴定出浮游植物215种,从组成来看,均属于硅藻-绿藻型,蓝藻含量居第3位.蓝藻主要分布在1倍透明度(SD)以上的水层,硅藻主要分布在1SD～2SD之间水层,其余各 门藻类基本上集中分布在2SD以上水层,绿藻门中的栅藻(Scenedesmus),裸藻门中囊裸藻(Trachelomonas)则广泛分布于深水层中.不同水层的浮游植物密度差异很大,表层与底层的差异可达2倍以上.各水库浮游植物年平均密度和生物量分别为:金沙河123.2× 104 cells.L-1,1.283 mg·L-1:道观河258.6x 104 cells·L-1,3.335 mg·L-1；徐家河210.5× 104cells.L-1,2.740 mg·L-1;桃园河221.3× 104 cells·L-1,3.088mg·L-1.浮游植物生物量的水层分布除道观河为表层＞SD＞2SD＞3SD＞底层,其余3座水库均为SD＞表层＞2SD＞3SD＞底层.从水库之间来看,金沙河的Shannon-Wiener多样性指数(H)、Pielou均匀度指数(J)与其他3座水库各指数之间的差异均达到了极显著水平(P＜0.01),而道观河、徐家河、桃园河两两之间差异不明显.TN与浮游植物呈负相关,而TP与浮游植物呈正相关,但未达到显著水平(P＞0.05).水体的营养水平不同是4座水库浮游植物群落结构差异的主要原因.本研究旨在为水库渔业资源的合理利用,以及水库环境保护与水质评价等相关研究积累基础资料.
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