Abstract: A survey of zoobenthos in the lower reaches of Hanjiang River was carried out during May, 1990 to November, 1992. Forty_seven zoobenthic species, including 6 aquatic oligochaetes, 23 molluscs, 15 aquatic insects and 3 species of other taxa, were identified. The average density of zoobenthos in the lower reaches was 332.7ind穖^-2 and the biomass was 73.379g穖^-2 . The water quality of the river was assessed with Beck, Shannon, Simpson and other biotic indices. The results showed that most parts of the river were with clean water except specific transects.

Key words: extracellular polymeric substance, microbial assemblage, extracellular protein, protein analytical technique.