南湾水库底栖动物群落结构初步研究

Preliminary Study of Macroinvertebrate Communities in Nanwan Reservoir

为了解南湾水库底栖动物现状,于2015～2016年对该水库按季节进行了周年调查。调查中共检出20种(水生昆虫12种,寡毛类7种,其他类群1种),全年优势种为霍甫水丝蚓、德永摇蚊和前突摇蚊。经MRPP检验,底栖动物群落结构存在季节差异,春季显著不同于夏秋冬季,且夏秋冬季群落结构差异不显著。底栖动物平均密度和生物量分别为171.43 ind./m2和0.503 4 g/m2,寡毛类对密度的贡献比为75.20%,水生昆虫对生物量的贡献比为80.65%。底栖动物密度和生物量季节差异显著,Shannon-wiener指数春季>冬季>夏季>秋季。群落状态指数(Integral Index of Communities State,IICS)季节差异显著,南湾水库水生态状况春冬季要好于夏秋季。底栖动物现存量处于较低水平可能与该水库季节性水温分层现象突出以及水体处于富营养状态有关。结合水质理化指标,该水库采用IICS指数对水生态状态进行定量评估较为适宜。根据IICS指数与环境因子相关性分析结果,发现随着水温的升高,藻类的过度旺盛生长对底栖动物种群具有一定的抑制作用,特别是水体交换率较低且存在较长时间温跃层的水库。

During 2015 and 2016,four season investigations were carried out in Nanwan Reservoir to understand the current status of macroinvertebrates.A total of 20 taxa(12 taxa of aquatic insects,7 taxa of oligochaetes,and 1 taxa of others) were collected and the annual dominant taxa were Limnodrilus hoffmeisteri,Tokunagayusurika sp.,and Procladius sp..Significant seasonal differences in the communities were verified by MRPP tests,and the communities in spring was significantly different from that in the other seasons,but there were no significant differences in the communities between summer,autumn and winter.The average density and biomass of the macroinvertebrates were 171.43 ind./m2 and 0.503 4 g/m2 respectively.The contribution ratio of oligochaetes to density was 75.20%,and that of aquatic insects to biomass was 80.65%.The differences in density and biomass between seasons were significant,and the Shannon-Wiener index was used to rank the order as spring >winter > summer > autumn.The integral index of communities state(IICS) of macroinvertebrates had significant seasonal variations.In Nanwan Reservoir,the ecological conditions were better in spring and winter than in summer and autumn according to the IICS values.The low standing crop was possibly related to the seasonal water temperature delamination phenomenon and the eutrophic state of waterbody.In combination with the water physicochemical parameters,it was suitable to use the IICS index for evaluation of the water ecological conditions of Nanwan Reservoir.Furthermore,according to the results of correlations between IICS and environmental factors,it could be concluded that with the increasing water temperature,the excessive growth of algae had a certain inhibitory effect on the reproduction and growth of macroinvertebrates,especially in a thermal stratified reservoir with lower water exchange rate.