Impacts of reclamation and aquaculture on the wintering waterbird assemblage at a floodplain lakeshore based on multidimensional diversity

The floodplain lakeshores have pronounced hydrological and topographical gradients, high habitat heterogeneity, and abundant food sources, providing suitable habitats for wintering and stopping waterbirds. However, certain areas are experiencing ecosystem changes along the lakeshore due to lake development. Huayanghe lakes are composed of several shallow lakes, located in the middle and lower Yangtze River floodplain, which are important wetlands for the waterbirds on the East Asian–Australasian Flyway. In recent decades, intensive reclamation and aquaculture have transformed the lakeshore into an ecosystem characterized by three distinct wetland types: lakes, fishponds, and paddy fields. Changes in habitats have considerable impacts on lakeshore biodiversity, with waterbirds exhibiting particularly high sensitivity to changes in wetlands. Therefore, to support waterbird community conservation, the consequences of anthropogenic activities on lakeshore waterbird diversity must be elucidated. Integrated studies of taxonomic, phylogenetic, and functional diversity and dissimilarity can provide a multifaceted indication of the assemblage patterns and dynamics of lakeshore waterbird communities under anthropogenic disturbance. Accordingly, in the current study, we examined the diversity and dissimilarity of waterbirds in the lake, fishpond, and paddy field wetlands during wintering periods. The taxonomic and functional diversity of waterbird communities was significantly lower in fishponds and paddy fields than in lakes. Phylogenetic diversity was also significantly lower in paddy fields than in lakes; however no significant differences were observed between fishponds and lakes. The community's taxonomic, phylogenetic, and functional dissimilarities were significantly lower in fishponds and paddy fields than in lakes, and lower in paddy fields than in fishponds. The temporal dynamics of the waterbird community diversity and dissimilarity varied significantly, with larger fluctuations in fishponds and lakes than in paddy fields. Specifically, lakes exhibited an initial increase and subsequent decrease, while fishponds and paddy fields showed a continuous, gradually declining trend. During the early wintering period, the dissimilarity of waterbird communities was higher in fishponds and paddy fields than in lakes. Additionally, the diversity and dissimilarity of waterbird communities increased in fishponds during the wintering period. In summary, artificial wetlands can provide temporary habitat for waterbirds; however, the reclamation of lakeshores into fishponds and paddy fields has reduced the wetland capacity to maintain waterbird diversity. These findings provide critical insights to inform the design of effective management strategies for waterbirds and wetland habitats on floodplain lakes.