Spatial and temporal variations in sediment enzyme activities and their relationship with the trophic status of Erhai Lake

The spatial and temporal variations in the activity of six microbial enzymes (invertase, urease, alkaline phosphatase, protease, peroxidase, and polyphenoloxidase) present in the sediment of Erhai Lake, China were investigated. Enzyme activities peaked in summer. This phenomenon can be attributed to high temperature and sediment organic matter accumulation, which could be traced to the breakdown of algal bloom. In addition, sediment enzyme activities exhibited apparent spatial heterogeneity across the lake, but individual enzymes showed similar spatial patterns of activity. Moreover, sediment enzyme activities were found to be closely related to the water quality of Erhai Lake. Enzyme activities were also significantly correlated with sediment total nitrogen and organic matter, implying that the sediment enzyme can be used as a biological indicator that reflects the sediment status. The investigation of sediment enzyme activities can facilitate a comprehensive understanding of the process of nutrient cycling and the mechanisms underlying lake eutrophication.