大纵湖大型底栖生物群落结构及水质生物学评价

Macrozoobenthos community structure and water quality bioassessment for Dazong Lake in Lixiahe area

大纵湖位于长江、淮河两大水系交融的里下河地区洼地中心地带,是江苏省级规划保护的重点湖泊之一。近20 a来,在人类活动影响下,大纵湖生态环境受到了严重挑战。底栖动物是水生态系统中的重要组成部分,在能量流动和物质循环中起着承上启下的作用。于2015～2016年对大纵湖底栖动物群落分布特征进行了监测分析。结果表明:在调查期间,大纵湖共采集出底栖动物10种(属),其中寡毛类、摇蚊幼虫、软体动物及其它底栖动物平均密度分别为132.27,100.52,82.02,5.29 ind./m^2,平均生物量分别为1.52,0.61,168.74,0.02 g/m^2。底栖动物密度与生物量均呈现出时空分布不均匀的特征。大纵湖底栖动物优势种主要为苏氏尾鳃蚓、霍甫水丝蚓、中国长足摇蚊和环棱螺。基于调查结果,选用4种不同的生物指数(BPI生物学指数、Shannon-wiener指数、Goodnight生物学、Wright指数)对大纵湖进行水质生物评价,结果表明大纵湖目前处于轻度-中度污染阶段。

Dazong Lake located in the middle of low-lying Lixiahe Region,a convergence area of the Yangtze River and the Huaihe River,and is one of the most important province-level protection lakes in Jiangsu Province.However,Dazong Lake is suffering serious environmental problems due to human activities in last two decades.Macrozoobenthos,an important part of aquatic ecosystems,contribute significantly to the circulations of energy and materials.In this study,macrozoobenthos community structure was investigated in Dazong Lake from 2015 to 2016 and 10 taxa macrozoobenthos were found.The average density of Oligochaeta,Chironomidae,Mollusca and other groups were 132.27,100.52,82.02,5.29 ind./m^2,while the average biomass were 1.52,0.61,168.74,0.02 g/m^2 respectively.The density and biomass of macrozoobenthos varied spatiotemporally.Branchiura sowerbyi,Limnodrilus hoffmeisteri,Tanypus chinensis,and Bellamya sp.were the dominant species in Dazong Lake.The results of water quality bioassessment using four different indexes(i.e.BPI,Shannon-wiener,Goodnight and Wright indexes)indicated that Dazong Lake was at the status of mild-intermediate polluted.