Li Wu

Urbanization significantly impacts river ecosystems, altering fish community structure and dynamics and posing challenges to the sustainable management of these vital resources. In the heavily urbanized Haihe River in China, understanding the spatial and seasonal variations of fish communities and the environmental factors influencing them is crucial for effective conservation and sustainable management. This study investigated fish communities and environmental variables at ten sites along an urbanization gradient in the upstream reach of the Haihe River over four seasons in 2023. A total of 6710 individual fishes representing 30 species were collected. The results showed that the most urbanized section exhibited higher species diversity but was dominated by tolerant, omnivorous species with similar functional traits, indicating functional homogenization. In contrast, less urbanized sections displayed greater seasonal fluctuations and supported species with specialized traits. Key environmental factors influencing fish community dynamics included nitrogen levels, water temperature, dissolved oxygen, and the abundance of the submerged macrophyte Potamogeton crispus. These factors varied spatially and seasonally, mediating the effects of urbanization on fish communities. The findings highlight the importance of environmental factors in shaping fish community dynamics in urban rivers and underscore the need for integrated management strategies that consider both anthropogenic impacts and natural influences to conserve fish diversity, river maintain ecosystem health and ensure long-term sustainability. Sustainable management practices that balance development with environmental protection are vital for preserving ecological integrity and enhancing the resilience of urban river systems to challenges such as urbanization.

To analyze the structural characteristics of zooplankton functional groups (ZFGs) and their correlation with environmental physicochemical factors in the Chaohu Lake Basin, water samples were collected from October 2019 to July 2020, and the zooplankton species and ZFGs were investigated. A total of 250 species, including 88 protozoa, 115 rotifers, 28 cladocerans, and 19 copepod species, were detected and divided into 16 ZFGs. The ZFGs exhibited obvious spatiotemporal heterogeneity. ZFGs in the Chaohu Lake were notably different from those in rivers and were different between the rivers. In the ecosystem, network analysis showed that protozoan algae/protozoan bacteria (PA/PB), rotifer particle filter (RF), and rotifer small predator (RSG) were important in the spring, summer, and autumn that and small zooplankton filter (SCF) was important in spring, autumn, and winter, while the importance of other ZFGs changed with seasons. Redundancy analysis showed that the environmental factors with a strong correlation between the ZFG compositions differed in each season. Different ZFGs exhibited different correlations with environmental factors. This study showed that ZFGs were closely related to environmental factors and that functional traits can reflect responses to changes in the water environment.