Comparative analysis of the spatio-temporal dynamics of rotifer community structure based on taxonomic indices and functional groups in two subtropical lakes.

Little research has focused on how rotifer communities respond to eutrophication based on their combined taxonomic and functional indices. In this research, the relationship of the environment and rotifer communities was comparatively investigated in two subtropical lakes over one year. The taxon-based indices, including species number (S), Margalef index (D), Simpson index (d), Shannon-wiener index (H'), and functional traits relying on the guild ratio (GR) and the modified guild ratio (GR') from the moderately eutrophic Lake Xiyanghu were significantly lower than those from the slightly eutrophic Lake Jinghu. Redundancy analysis (RDA) showed that both lakes were distinct from each other. Taken together, the findings indicate that trophic state was an important factor affecting rotifer community structure. In addition, the average annual GR' of Lake Xiyanghu was <0, suggesting the dominancy of microphagous rotifers. Over time, S, D, d, and H' were positively correlated with temperature and phosphorus levels in Lake Jinghu, but were negatively correlated with NH-N levels in Lake Xiyanghu. Only GR' was negatively associated with chlorophyll-a in Lake Xiyanghu, implying that the functional index (GR') might be an effective tool to explore the relationship between trophic state and the rotifer community in seriously eutrophic lakes.