Monitoring and Managing Freshwater Ecosystems in the Face of Urbanization

Abstract

Freshwater ecosystems are one of the most critically endangered ecological systems in the world due to increasing urbanization. Impervious surfaces, stormwater runoff, pollutants from industries, microplastics, and salinization are some factors introduced through urbanization and responsible for deteriorating the physicochemical stability and biodiversity of rivers, lakes, and wetlands. While addressing such an environmental issue becomes increasingly urgent, comprehensive frameworks linking real-time ecological monitoring and management are relatively nascent. This research aims to contribute to filling the gap regarding the management and monitoring of freshwater ecosystems by studying the Singanallur Lake system in Coimbatore, India a mid-sized Indian city undergoing rapid urbanization. Water quality parameters like dissolved oxygen (DO), biochemical oxygen demand (BOD), total dissolved solids (TDS), pH, turbidity, nitrate, and phosphate were evaluated across three sampling sites between June 2022 to May 2023. Bioindicators used for monitoring the lake's health include benthic macroinvertebrates and fish community indices. The results show spatial and temporal degradation gradients in physicochemical parameters where DO show a 38% reduction during monsoon flush events, while BOD exceeded permissible levels (>10 mg/L) at urban downstream sites. The Biotic Index demonstrated poor to fair water quality at 67% of sampled stations. Urbanization was found to account for 74% of the variation in the water quality index. These results show that there is an urgent need to develop integrated systems of monitoring that would include physical and biological aspects of water quality assessments. Several approaches to sustainable urban freshwater management are suggested.