Abstract: From May 2009 to February 2010, an investigation was conducted on the zoobenthos community in Gehu Lake, and the water quality of the Lake was assessed based on the structure of the zoobenthos community. A total of 35 zoobenthos species belonging to 3 phyla and 25 genera were identified, among which, Tanypus chinensis, Limnodrilus hoffmeisteri, Branchiura sowerbyi, L. claparedeianus, and Rhyacodrilus sinicus were dominated. The annual density of the zoobenthos averaged 374.1 ind·m^-2, and oligochaeta contributed most, occupying 77.4% of the total. The annual biomass averaged 17.78 g·m^-2, and molluscs had the most contribution (97.4%). The density and biomass of the zoobenthos were the highest in summer, but the lowest in spring and in winter, respectively. Among the observation stations, St14 had relatively higher zoobenthos density and biomass. The zoobenthos density and biomass varied greatly with season. The highest density occurred in summer, followed by in autumn, spring, and winter; the highest biomass occurred in summer, followed by in spring, winter, and autumn. The values of ShannonWiener diversity index, Margalef species richness index, Pielou index, and BI index suggested that the Gehu Lake was of moderate to serious pollution.

Key words: Sr²⁺, chum salmon, electro-probe microanalyzer, strontium sedimentation, strontium marking.