Abstract: To explore the characteristics of macrobenthic invertebrate community and ecosystem health status in river-lake intersection areas, we investigated water quality, sediment quality, and zoobenthos community in the intersection areas of 14 rivers entering Nansi Lake in September 2020 and April 2021. A total of 55 species were collected, belonging to 6 classes, 15 orders, and 39 families. Results of non-metric multi-dimensional scaling analysis showed that the similarity of zoobenthos community across all sampling sites in spring was higher than that in autumn. The community structure had high similarity among Xinxue River (S7), Panlong River (S9), and Beisha River (S11) in both seasons. Results of redundancy analysis showed that total phosphorus and COD_Cr in water and total carbon in sediment were the key factors affecting zoobenthos community. The scoring of biological monitoring working party (BMWP) index concluded the similar consequence with water quality characteristics, indicating that BMWP is a valid biological index for assessing the health status of the river-lake intersection areas in the Nansi Lake. The health status of major river-lake intersection areas in the Nansi Lake Basin was generally at the level of mild to moderate pollution. This study provides a basis for ecological restoration in river-lake intersection areas.

Key words: river and lake ecotone, zoobenthos, environmental factor, redundancy analysis, biological monitoring working party index, ecological health.