Integrated ecosystem health assessment of a macrophyte-dominated lake

A set of ecological indicators were proposed for the lake ecosystem health assessment via the application of structural, functional, and system-level responses of whole-lake ecosystems to land-use types, chemical stressors including nutrients and organic pollution, and physical stressors including water depth (WD) and grain size (GR). The structural metrics incorporated Chlorophyll c/Chlorophyll a (Chl c/a), Shannon diversity index (H), and proportion of Bacillariophyta (BAC). The functional metrics encompassed leucine amino peptide enzymes (LEU) and general primary productivity (GPP). The ecosystem level indicators consisted of eco-exergy (Ex), structural eco-exergy (Exst), and ecological buffer capacity (βTP-A). Using these indicators, we developed an integrated ecological health modeling method (IEHMM) for macrophyte-dominated lake health assessment. The IEHMM was designed to: (1) identify the relevant questions related to the health of the ecosystem; (2) analyze the lakeʹs ecosystem structure including the pelagic and benthic pathways and use these results to determine the modelʹs structure and complexity; (3) establish a whole-lake ecological conceptual model; (4) calculate the lakeʹs ecosystem health indicators; (5) assess lake ecosystem health using these different indicators; and (6) compare the assessment results with different calculation methods. The IEHMM conceptual model included 5 sub-models and 15 state variables. The results of the case study in Baiyangdian Lake (China) demonstrated that the IEHMM provided comprehensive assessment results that corresponded with the lakeʹs actual health state.