Abstract: In order to understand the relationships between habitat gradient and macrobenthos composition, a field investigation was conducted on the macrobenthos community in three different habitats, i.e., riparian zone with emerged vegetation (zone Ⅰ), lakebay zone with submerged vegetation (zone Ⅱ), and open water zone outside the weir (zone Ⅲ), in a riparian ecological restoration pilot area of Gonghu Bay, Taihu Lake in 2010-2011. A total of 18 macrobenthos species were identified, of which, 7 species only existed in one habitat type, and 5 of the other 11 species had significant difference in abundance across the habitat gradient. As for the distribution of the functional feeding groups of macrobenthos, significant differences were observed among the habitat types. Scrapers had the highest relative abundance in zone Ⅰ, while gathercollectors and filtercollectors had the highest relative abundance in zone Ⅱ and zone Ⅲ, respectively. The redundancy analysis on the effects of water quality on the macrobenthos composition showed that annelids and aquatic insects were positively correlated with water DO, NO₃^--N, and PO₄^3--P, while mollusks were negatively correlated with water NO₃^--N and PO₄^3--P. Some mollusks were able to endure the stress from low DO, and correlated positively with water NH₄⁺-N and COD. Overall, the differences in the hydraulic conditions, water quality, and substrates among the three habitat types had great effects on the distribution of macrobenthos, leading to the formation of three macrobenthos communities with significant differences in life form and feeding attributes.

Key words: soil moisture and salinity, spatial distribution, influence factors, Manas river catchment.