Assessment of the Status of Microbiota Characteristics, Physico-Chemical Characteristics, Water Quality Index, and Trophic Level Index at Beira Lake, Colombo, Sri Lanka

Abstract

Beira Lake, a significant water body in Colombo, Sri Lanka, faces severe ecological degradation due to rapid urbanization and anthropogenic activities. This research aims to evaluate the lake's health by integrating physico chemical parameters, microbial diversity, and indices like the Water Quality Index (WQI) and Trophic Level Index (TLI). Water samples were collected from 20 strategically chosen locations, and key parameters such as temperature, pH, electrical conductivity, salinity, dissolved oxygen, biochemical oxygen demand at 20°C, chemical oxygen demand, ammonia, nitrate, and phosphate were measured. Microbial assessments included cyanobacteria, zooplankton, diatoms, aerobic bacteria, fecal coliforms, and chlorophyll-a content. The results showed significant spatial variability in water quality and microbial communities, with some locations exhibiting harmful blooms, fecal contamination, and eutrophication. The WQI values indicated poor water quality, while TLI values confirmed hypertrophic conditions across the lake. A positive correlation between WQI and TLI underscores the interconnectedness of water quality and nutrient enrichment. This comprehensive assessment highlights the need for integrated management strategies to restore Beira Lake's ecological balance.