Relation between stream habitat conditions and macroinvertebrate assemblages in three Chinese rivers

Field investigations of macroinvertebrates in three Chinese rivers were conducted twice in 2009. Altogether 88 taxa were identified. Annelids, arthropods and mollusks were the dominant taxonomic group in the Songhua River, the Yongding River and the West River, respectively. Collector-gatherers were the most abundant group in the relatively lentic river sites, where the bottom was largely organic-rich silt. Epilithic collector-filterers and scrapers were dominant in the lotic river sites, where the bottom was mainly dominated by stone substrate. Based on statistical analyses, water physico-chemical variables (total phosphorus and conductivity) played a key role in structuring macroinvertebrate assemblages in silt substrate, while hydrological variables (median grain size of substrate and water velocity) mainly affected macroinvertebrate assemblages in stone substrate. In silt substrate, density and biomass of collector-gatherers increased with increasing total phosphorus. In stone substrate, total density peaked in the cobbles, while total biomass peaked in the bedrock.