Temporal variation in multidimensional benthic macroinvertebrate diversity in Lake Chaohu, China, from 2018 to 2024

Benthic macroinvertebrates are widely used as indicators of freshwater ecosystem changes due to their sensitivity to environmental disturbance and important ecological functions. However, long-term variations in multiple biodiversity dimensions of benthic communities under eutrophication and seasonal environmental stress remain poorly understood. In this study, quarterly surveys were conducted at eight sites in Lake Chaohu from 2018 to 2024 to investigate temporal dynamics of benthic macroinvertebrate communities and their environmental drivers. A total of 33 taxa were identified, with communities consistently dominated by oligochaetes and chironomids. Density and biomass varied significantly among years and quarters, whereas species richness showed significant quarterly variation and a Year × Quarter interaction but no significant main effect of Year. Community structure Mixed-effects models further identified associations between selected. The dbRDA model explained 11.59% of the variation in biodiversity indices (R 2 = 0.116, P = 0.0007), with NH 4 + -N, COD Cr , and TN identified as significant predictors among the measured water-column variables. Mixed-effects models revealed additional associations with composite biodiversity scores, although the statistical support for some relationships was sensitive to the omission of individual observations or sites. Temporal changes were reflected mainly in community composition, functional diversity, and taxonomic distinctness rather than interannual differences in species richness. These findings support integrating multiple biodiversity dimensions into the ecological assessment of eutrophic shallow lakes.