剑湖摇蚊幼虫的空间分布与水质评价

Spatial Distribution of Chironomid Larvae and Water Quality Assessment in Jianhu Lake

通过研究云南剑湖摇蚊幼虫的种类组成和空间分布,结合水质生物学评价指数,分析其群落结构特征并评价水质现状,旨在为该湖泊水生态系统健康评价和发展渔业生产提供基础数据。于2011年1月、4月、6月和10月分冬、春、夏、秋4个季节在剑湖设定11个采样点,进行摇蚊幼虫群落调查。结果表明,摇蚊幼虫共检出13种,隶属3亚科、6属,优势种为中华摇蚊(Chironomus sinicus)、溪流摇蚊(Chironomus riparius)、花纹前突摇蚊(Procladius choreus)和多足摇蚊(Polypedilum spp.);其中中华摇蚊为全湖性分布,其分布平均水深为162 cm,前突摇蚊属种类分布的平均水深最大,其它种类为局部性分布。摇蚊幼虫的平均密度冬季最高,为858.091个/m^2,夏季最低,为154.182个/m^2;冬季生物量最高,为15.741 g/m^2,其它3季均处在较低水平,其中秋季最低,仅1.245 g/m^2。根据水质生物学评价指数,目前剑湖的水质等级为中-重污染,已达富营养化水平;同时给出了剑湖水环境治理和控制建议。

Jianhu Lake, located in Jianchuan County of Dali Bai Autonomous Prefecture, Yunnan Province, is a typical plateau fresh water lake. To date, no research had been reported on the community structure of chironomid larvae in Jianhu Lake and basic ecological information on chironomid larvae is lacking. In this study, we investiga- ted the community structure of chironomid larvae in Jianhu Lake, focusing on species composition, density, bio- mass and spatial distribution. The results were used to determine the biological index of the chironomid community, which was then used to assess the water quality of Jianhu Lake. The research provides base data for evaluating the ecosystem health and fishery management of Jianhu Lake. A seasonal investigation of the chironomid larvae commu- nity was carried out at 11 sampling sites in January, April, June and October of 2011. A total of 13 chironomid species from 6 genera and 3 subfamilies were identified, dominated by Polypedilum sp. , Chironomu~ sinicus, Chi- ronomus riparius, and Procladius choreus. Chironomus sinicus was distributed throughout the lake at an average depth of 162 cm. Procladius spp. was found at an average maximum depth of 323.3 cm and the other species were found higher in the water column. The average density of chironomid larvae was 335.25 ind/m2, with a maximum density of 858.091 ind/m2 （winter） and a minimum density of 154. 182 ind/m2 （summer）. The highest average chironomid larvae biomass occurred in winter （15. 741 g/m2） and the lowest occurred in autumn（ 1. 245 g/m2）. The ranges of the Shannon-weaver index, Margalef richness index, Pielou evenness index and biological index of the chironomid larvae community were, respectively, 0 - 1.73, 0 - i. 33, 0 - 0.79, and 1 - 3. The biological e- valuation indices, based on ehironomid diversity and community structure, indicate that the water in Jianhu Lake is moderately-seriously polluted and eutrophic. The primary pollutant sources are wastewater from aquaculture and municipal sewage. To improve water quality in Jianhu Lake, we suggest that the management department strengthen environmental controls, construct more garbage disposal and scientifically set the stocking density for cage culture. and sewage treatment plants, introduce herbivorous fish and scientifically set the stocking density for cage culture.