基于底栖动物完整性指数的洞庭湖典型断面的水质评价

2010年在枯水期、平水期、丰水期对洞庭湖的7个典型断面进行了大型底栖无脊椎动物采样,共获得底栖动物40种,其中节肢动物16种、软体动物18种,环节动物6种。根据Shannon-Wiener物种多样性指数确定了4个相对清洁的断面和3个污染断面,然后进行23种生物指数的综合评估,结果表明,(甲壳动物+软体动物)分类单元数、Shannon-Wiener物种多样性指数与Goodnight-Whitley指数3个底栖动物生物指数可以用作辨别洞庭湖典型断面水质的敏感生物指数。通过5、3、1记分法对3种生物指数统一量纲后,获得变化范围为3～15的综合生物指数,运用四分法划分出洞庭湖典型断面水质辨别的生物基准:3～6,差;7～9,一般;10～12,好;13～15,很好。据此对7个断面进行重新记分,获得了洞庭湖典型断面水质的基本分区现状:虞公庙、万子湖、目平湖3个断面的水质良好,而鹿角、坡头、南嘴及东洞庭湖4个断面的水质较差。该水质生物学基准基本适合评价洞庭湖典型断面的水质状况。

Bioassessment on Water Quality Based on Biotic Integrity Index of Macroinvertebrate in Representative Sections of Dongting Lake, China

To develop benthic macroinvertebrate based multmietrics for the bioassessment of the water quality of Dongting Lake, benthic macroinvertebrate assemblages were sampled at 7 sections of Dongting Lake in different seasons in 2010. A total of 40 species of the benthos were collected:16 species of Arthropoda, 18 species of Mollusca and 6 species of Annelida. The dominant benthos had an abundance ranging from 32 to 208 individuals·m-2 and obviously different across the sampling sections. Based on Shannon-Wiener biotic index discriminatory criteria, 4 sections were considered relatively clean while the remaining 3 sections were polluted. A comprehensive evaluation of 23 metrics was carried out. The results showed that 3 metrics(.i e., No. of Mollusca & Crustacea Taxa, Shannon-Wiener Species Diversity Index and Goodnight-Whitley Index)were sensitive. A score of 5, 3 or 1 was assigned to every metric for standardization of the metrics, and a multmiet- ric on a scale ranging from 3 to 15 for bioassessment was developed for each section by addition of its 3 metrics. Four levels of discriminatory biocriteria for water quality were eventually proposed by quartation:3~6, poor; 7~9, fair; 10~12, good; and 13~15, very good. The rescored re- sults from the 7 sections showed that the water quality of Yugongmiao, Wanzi Lake and Muping Lake was good, whereas that of Potou, Lujiao, Nanzui and East-Dongting Lake was relatively poor. Basically, the discriminatory biocriteria are suitable for the assessment of the water qual- ity in representative sections of Dongting Lake.