Impact of Environment on the Spatio-Temporal Distribution of Rotifers in the Tidal Guangzhou Segment of the Pearl River Estuary, China

Rotifers were studied at two sites (Zhongda and Huangpu) in the tidal Guangzhou segment of the Pearl River in China, from April 2004 to March 2007. Fifty-six species were recorded. Rotifers, were most abundant during late fall. Overall, densities ranged from 4 to 5975 ind. L-1, with mean densities of 1627 +/- 233 ind. L-1 at Zhongda and 1051 +/- 147 ind. L-1 at Huangpu. There was a positive correlation between rotifer density and chlorophyll a concentration at both sites. At Huangpu, rotifer abundance was significantly negatively correlated with salinity. Analysis of partial correlations suggested that the fluvial hydrodynamics and the physico-chemical characteristics of the river affected chlorophyll and the development of rotifer populations was determined by chlorophyll in the lower reaches of Pearl River. The results also show that rotifer density estimates are significantly affected by sampling method.