长湖浮游动物群落结构及其与环境因子的关系

为研究长湖浮游动物群落结构及其与环境因子间的关系,于2012年4月至2013年1月进行了4次调查采样。共鉴定出浮游动物67种(不包括原生动物),以轮虫种类为主(42种),其丰度与生物量均占据较大优势。浮游动物丰度的季节性差异显著,夏季最高(4412ind./L),冬季最低(831ind./L)。季节间的物种更替率大于59%,但优势种种类的季节变化不明显。优势种共8种,均为轮虫,萼花臂尾轮虫(Brachiouns calyciflorus)、针簇多枝轮虫(Polyarthra trigla Ehrenberg)是四个季节均出现的优势种,P.trigla Ehrenberg的优势度与出现频率均是各个季节的最大值,各季节这两种优势种的丰度和在总丰度的占比均超过59.13%。依据Shannon指数、Pielou指数、Margalef指数评价长湖水体处于中度污染,肥度指数评价长湖处于富营养状态。相关性分析、多元逐步回归方程、冗余分析的结果显示:水温是影响长湖浮游动物群落结构季节变化的关键因子;浮游植物表征含量chl a也是影响长湖浮游动物群落结构的关键因子,总氮、总磷通过影响浮游植物的群落结构间接地影响浮游动物的组成;能耐受较高p H的B.calyciflorus在长湖碱性水体中有较好的适应性;夏季马洪台区较低的溶解氧一定程度上限制了该区域轮虫的生长,总悬浮物通过降低溶解氧对浮游动物产生间接作用;化学需氧量对P.trigla Ehrenberg、螺形龟甲轮虫(Keratella cochlearis)等耐污种的影响较大,并对浮游动物的丰度产生正向作用。

COMMUNITY STRUCTURE OF ZOOPLANKTON AND THE DRIVING PHYSICOCHEMICAL FACTORS IN CHANGHU LAKE

To understand the community structure of zooplankton in Changhu Lake and explore the relevant physicochemical factors on their distribution, we conducted seasonal investigations in 19 sites in the lake from April, 2012 to January, 2013. Sixty-seven zooplankton species were identified (excluding protozoa), most of them were rotifers (42 species) having the highest abundance and biomass. The seasonal difference in zooplankton abundance was significant, highest in summer (4412ind./L) and lowest in winter (831ind./L). In addition, the species composition of zooplankton changed greatly in season; and the average of species seasonal subrogation was greater than 58.14%, while for dominant species, it was insignificant. Eight dominant species were determined and all were rotifers. Brachiouns calyciflorus and Polyarthra trigla were the dominants during the survey; the dominance and occurrence frequency of P. trigla were the largest in every season, taking 59.13% of the total. Meanwhile, the water quality of the lake was assessed, showing moderate pollution as indicated by the Shannon Index, Pielou Index and Margalef Index, and was in eutrophic state according to E Index. Results of correlation analysis, stepwise multiple regression and redundancy analysis show that water temperature and chlorophyll a concentration were two main factors on seasonal succession of zooplankton community in the lake, while total phosphorus affected the zooplankton community indirectly by changing composition of phytoplankton species. Featured with alkali tolerance, B. calyciflorus was better adapted in alkaline water of Changhu Lake. The relatively lower dissolved oxygen in the Mahongtai Area of the lake limited the growth of rotifer in summer, and total suspended solid affected zooplankton indirectly due to water clarity decrease. Chemical oxygen demand influenced tolerant species such as P. trigla, Keratella cochlearis, and had positive effect on zooplankton abundance.