Abstract:

The relative importance of forces driving the seasonal changes of a rotifer community in Lake Qiaodun, located in China, was assessed through monthly sampling. The lake was eutrophic, characterized by high concentrations of nutrients and Chl a, as well as, low transparency. The water temperature and the trophic status of the lake were the most important physicochemical factors influencing rotifer abundance and community dynamics. Due to the rarity of largesized cladocerans in abundance, cladocerans showed no negative impacts on rotifer abundance. Diaphanosoma brachyurum was the most important cladoceran in impacting rotifer community dynamics. However, the positive association of most dominant rotifers with D. brachyurum might be a reflection of their common favorites for high trophic level and high water temperature. Among the phytoplankton, Chlorophyta was the most important phylum in determining total rotifer density, and Cryptomonas the most important genus in shaping the rotifer community. The three explanatory data sets showed a similar contribution on seasonal rotifer community dynamics. These results suggest that in this eutrophic lake, the seasonal changes of a rotifer community are likely controlled by physicochemical factors and food resources. Crustacean zooplankton might play only a minor role in shaping the rotifer community