Articles · Open Access Policy
Abstract
Assessment of ecological recovery in polluted lakes is a large yet difficult task because traditional approaches of water quality evaluation cannot discern interactions between chemical, physical, biological and functional components of ecosystems, which are highly dynamic and complex. In this study, Multi-Indicator Assessment Framework (MIAF) was developed for evaluating the ecological recovery of polluted lakes by systematically quantifying variation in water quality, sediment quality, biological diversity and ecosystem functioning in lake ecosystems into a single unified system. Ecological indicators in the MIAF were first normalized, weighed equally in a group and then combined in to one index - the Composite Ecological Recovery Index (CERI). Based on its values, lakes can be classified into five recovery levels, i.e., seriously degraded lake, weak recovery lake, moderate recovery lake, strong recovery lake and highly recovered lake. Four lakes with various degrees of pollution and restoration status were tested, and the obtained CERI values ranged from 18.75 to 93.50, respectively. Additionally, quarterly monitoring indicated that actively restored lake showed a 21.35-point increase in CERI value over 4 sequential quarters, suggesting that the lake is undergoing ecological recovery. The results indicate that single-parameter assessment based only on conventional water quality conditions cannot sufficiently measure the progress of ecological restoration, but multi-parameter ecological assessment based on all four ecological indicators is more comprehensive in measuring the status of lake ecosystems. This framework can be effectively used for inter-lake comparison, deciphering the role of lake restoration processes, and systematic monitoring of restoration effectiveness. Overall, it can offer a transparent and flexible decision support method for evidence-based lake restoration and sustainable freshwater management.