Integrated Evaluation of Toxicity and Seasonal Water Productivity in Urban Lakes: A Multimodal Approach to Aquatic Ecosystem Health

This study evaluates the ecological health of three lakes in North Bangalore: Ullal, Herohalli, and Lingadheeranahalli by combining primary productivity metrics with developmental toxicity assays using zebrafish. Primary productivity was measured using the light and dark bottle method and chlorophyll analysis. Herohalli Lake showed the highest gross (10.67±9.50) and net productivity (9.40±13.36) along with elevated chlorophyll levels (46.9±13.1), indicating a healthier aquatic ecosystem. In contrast, Lingadheeranahalli Lake exhibited very low productivity and chlorophyll levels, pointing to anthropogenic stress and eutrophic degradation. Complementing this, zebrafish bioassays revealed notable variations in embryonic heart rate, somite development, and acetylcholinesterase (AChE) activity across the lakes. Herohalli Lake showed minimal toxicity, while Lingadheeranahalli Lake (0.0000263 µmol/min) exhibited pronounced neurotoxic effects correlating with poor productivity. The findings highlight a clear relationship between pollution load, aquatic productivity and biological impact, underscoring the importance of multimodal assessment strategies in urban lake monitoring and management.