关键词: 长江流域, 河流生态, 底栖动物, 河床演变, 生态评价

Abstract:

The aquatic ecology of the Yangtze River Basin was investigated and evaluated by using benthic invertebrate as indicator species.Investigation and sampling of water and benthic invertebrates were conducted from 2005～2007 at 36 selected sites on the upstream tributaries，middle and downstream reaches and riparian lakes of the Yangtze River.The water quality of the sites was evaluated with Hilsenhoff biotic index and compared with the results of chemistry analysis.The results show that the water in the most upstream tributaries are of high quality，water in the middle reaches of the Yangtze River and riparian lakes are slightly and moderately polluted；and the water quality in the lower reaches is even lower.The individual density，taxa richness and biodiversity of benthic invertebrate are high at the upstream sites，moderate in the riparian lakes of middle reaches，and low at the sampling sites in the middle and downstream reaches.Fluvial process condition has a significant effect on the benthic assemblage structure.This paper concludes the pedigrees of the benthic fauna in four types of fluvial process conditions for the Yangtze River Basin.Stable streambed provides the best habitat for biocommunity and has the highest biodiversity.The biocommunity is stressed in incised channels and the biodiversity is lower.In the stream experiencing siltation the habitat is seriously impaired and the biodiversity is even lower.In the stream with strong bed load movement there is no benthic macroinvertebrate.

Key words: the Yangtze River Basin, river ecology, macroinvertebrate, fluvial process, ecological assessment