Quantifying the ecological stability of artificial aquatic ecosystems: a case study of an artificial lake in Chengdu, China

An urban artificial lake is generally constructed as a macrophytic lake ecosystem; it has a simple ecosystem structure that results in a fragile ecosystem and weak stability. The ecosystem stability obviously changes with the water quality and the season, especially in summer and autumn. The purpose of this study was to establish a stability evaluation system for an artificial lake ecosystem and verify the system applicability using Lake Luxe as a case study. The system was established by the following three steps: (1) select reference period; (2) establish seasonal and annual evaluation methods by determining the ecological units by an ecological checklist (the populations and communities of phytoplankton, zooplankton, and benthos) and then calculating the seasonal stability indices (SIs) and annual stability indices (SIy) of each ecological unit; calculating each seasonal or annual ecosystem stability index using these calculated SI and ecological units attributes; and calculating the ecosystem stability index for many years; (3) obtain the evaluation results. The results obtained by the seasonal evaluation method showed that the ecosystem community structure was unstable in spring and the total ecosystem biomass was unstable in summer. The redundancy analysis results between phytoplankton stability values and environmental variables showed that dissolved oxygen (DO), total nitrogen (TN), and chlorophyll a (Chla) were the main driving variables that could be used as indicators for the sustainable management of artificial lakes.