Zooplankton Community Stability and Environmental Filtering in a Shallow Eutrophic Lake

Zooplankton are key regulators of trophic interactions and nutrient cycling in shallow eutrophic lakes and are sensitive indicators of ecological responses to anthropogenic pressures. This study was conducted to understand ecosystem dynamics in Changhu Lake, a typical shallow eutrophic lake in China. We conducted monthly surveys from June 2023 to May 2024 in Changhu Lake. Our work involved identifying zooplankton species and analyzing their assemblages. We used redundancy analysis (RDA), a neutral community model, and structural equation modeling (SEM) to identify key environmental drivers and understand community assembly processes. We identified 102 zooplankton species. The assemblages showed marked spatiotemporal variations, with small-bodied taxa dominating most seasons and sites, while large crustaceans remained scarce and peaked only locally in spring. Diversity peaked in autumn and declined sharply in summer. Compared to data from 2012 to 2013, total zooplankton abundance increased and small taxa became more dominant. RDA identified total phosphorus, chlorophyll a, ammonium nitrogen, and water temperature as key environmental drivers. Neutral community modeling indicated a higher migration rate in spring (R ² = 0.610, Nm = 47) versus dispersal limitation in winter (R ² = 191, Nm = 15). The community structure had a direct positive effect on ecosystem stability, whereas diversity had an indirect negative effect. The findings indicate a limited recovery of large-bodied species despite ongoing restoration initiatives. This study provides mechanistic insights into community assembly and resilience, offering valuable guidance for the adaptive management of lakes facing intensifying anthropogenic pressures.