环保疏浚对洱海西沙坪湾底栖动物群落结构的影响

为研究环保疏浚对富营养化湖泊底栖动物群落结构的影响，选取洱海沙坪湾开展为期一年的水生态监测与调查，对比分析了沙坪湾底泥疏浚前后、以及疏浚区与未疏浚区的水质指标、底栖动物群落结构及生物多样性指数。研究发现：底泥疏浚前，疏浚区与未疏浚区采集到的生物仅有霍甫水丝蚓(Limnodrilus hoffmeisteri (Claperede,1861))、苏氏尾鰓蚓 (Branchiura sowerbyi) 和摇蚊属一种(Chironomus sp.) 3种。在底泥疏浚过程中，疏浚区的底栖动物种类仅有4种，而未疏浚区的底栖动物已出现8种；疏浚结束后，与疏浚前和疏浚中相比，疏浚区的底栖动物种类明显增加，且种类多于未疏浚区。底栖动物密度和生物量结果表明，底泥疏浚前，疏浚区底栖动物生物量为0.731 g/m2，密度为560 ind./m2；疏浚结束后，疏浚区底栖动物生物量和密度的值分别为13.07 g/m2、1826.7 ind./m2，均高于疏浚前和疏浚中，且高于未疏浚区。此外，同未疏浚区相比，疏浚区的Simpson多样性指数和Shannon-Wiener 多样性指数的平均值分别由0.187、0.365增加到0.325、0.688，疏浚后生物多样性指数高于疏浚前。因此，实施环保疏浚工程能改善洱海湖湾底栖动物群落结构，并促进底栖动物群落多样性的增加。

Effects of Dredging on Zoobenthos Community Structure in West Shaping Bay, Erhai Lake

In order to study the effects of environmental dredging on benthos community structure in eutrophic lakes, a one-year water ecological monitoring and investigation was conducted in West Shaping Bay of Lake Erhai. Water quality indicators, zoobenthos community structure and diversity index in before and after sediment dredging of West Shaping Bay, as well as in dredged and un-dredged areas were compared and analyzed. The results showed that only Limnodrilus Hoffmeisteri (Claperede,1861), Branchiura sowerbyi and Chironomus sp. were collected in dredged and un-dredged areas before dredging. In the dredging process, only 4 species of zoobenthos were found in the dredged area, while 8 species were found in the un-dredged area. After dredging, the zoobenthos species increased significantly in the dredged area compared with those before and during dredging, and the species were more than those in the un-dredged area. The results showed that the biomass of zoobenthos was 0.731 g/m2 and the density was 560 ind./m2 before dredging. After dredging, the biomass and density of zoobenthos in the dredged area were 13.07 g/m2 and 1826.7 ind./m2, respectively, which were higher than those before and during dredging, and higher than those in the un-dredged area. In addition, compared with the un-dredged area, the mean values of Simpson diversity index and Shannon-Wiener diversity index in the dredged area increased from 0.187 and 0.365 to 0.325 and 0.688 respectively, and the biodiversity index after dredging was higher than before dredging. Therefore, environmental dredging can improve the community structure of zoobenthos and promote the increase of zoobenthos diversity in the bay of Lake Erhai.