Temporal dynamics of biodiversity in benthic macroinvertebrate communities from a 140-year sedimentary DNA record and their driving mechanisms

The ecological processes that influence the temporal components of β diversity and the interplay between taxonomic and functional β diversity are poorly understood. Therefore, the mechanisms that drive these processes and their ecological significance require further investigation. In this study, we utilized sedimentary DNA ( seda DNA) metabarcoding to analyze an approximately 140-year-long record of the benthic macroinvertebrate communities found in Lake Chenghai, southwestern China. Our findings revealed a decrease in taxonomic and functional dissimilarity within the β diversities of these communities from 1886 to 2017, with a pronounced homogenization trend observed between 1987 and 2017. This homogenization was primarily driven by taxonomic and functional turnover, which was caused by increased nutrient levels, especially increased total nitrogen content. In addition, autogenic organic matter inputs and increased evaporation also play a significant role in this phase. Predictive models indicate that to maintain optimal water quality and ecological health, total nitrogen and total phosphorus should be controlled to within approximate ranges of 0.565 mg/L ± 0.441 mg/L and 0.026 ± 0.001 mg/L, respectively. Our study highlights the role of temporal species turnover in shaping community structures and provides valuable insights for managing lake ecosystems and preserving biodiversity within benthic macroinvertebrate communities. • Homogenization drove community changes from 1987 to 2017. • Biotic homogenization was mainly driven by species turnover. • Beta diversity was primarily influenced by nutrient levels and evaporation. • TN water and TP water should be controlled within specific thresholds.