Rotifer community structure and its response to environmental factors in the Backshore Wetland of Expo Garden, Shanghai

We investigated rotifer community structure in the Backshore Wetland of the Expo Garden in Shanghai from September 2009 to August 2010. We identified 116 rotifer species, determined the dominant species and their relationships with environmental factors, and community diversity indices. Polyarthra trigla was the most common species over the four seasons and proportionally most dominant in spring and autumn, whereas Cephalodella exigua and Keratella cochlearis were the most dominant species in winter and summer, respectively. There was seasonal variability in species numbers, with the highest numbers in summer, followed by autumn and winter. The mean annual density was 815 ± 1346 ind./L and the biomass was 0.3649 ± 0.4940 mg/L. There were significant differences between months: the highest density (2723 ± 2926 ind./L) and biomass (0.7938 ± 0.8197 mg/L) occurred in June, while the lowest density (238 ± 271 ind./L) and biomass (0.0476 ± 0.0429 mg/L) occurred in May. Canonical correspondence analysis (CCA) indicated that temperature, pH, nitrite nitrogen (NO 2 -N), and total phosphorus (TP) were the most important abiotic factors affecting rotifer distribution. Our research showed that the adaptability of the rotifers to temperature was the important factor.