Macrozoobenthos community structure and its indicative significance in water quality bioassessment of Fenshuijiang Reservoir, Zhejiang Province of East China

A monthly investigation was conducted on the macrozoobenthos at 7 stations of Fenshuijiang Reservoir in Zhejiang Province of East China from November 2008 to October 2009. A total of 37 taxa were collected, most of which belonged to Oligocheata and Chironomidae. Limnodrilus hoffmeisteri was dominant in spring, summer and autumn, and Chironomus gr. plumosus was prevailing in winter. The collector-gatherer was the predominant group in species number, density and biomass. The mean annual density and biomass of the community were (488.0 ± 48.8) ind ·m^-2 and (1.86 ± 0.49) g·m^-2, respectively. There were no significant differences in the macrozoobenthic density among the stations and in the macrozoobenthic biomass among the stations and among the seasons, but the macrozoobenthic density had a significant seasonal variation, with the sequence of spring > summer > winter > autumn. Water temperature and water depth were the main factors affecting the spatial distribution of the macrozoobenthos. Shannon index and Goodnight-Whitley index were not suitable for the assessment, whereas the Wright index, Carlander index, Pielou index and trophic level index showed that this reservoir was slightly polluted.