Harmful Algal Blooms in Indian Lakes: Causes, Effects and Community-level Management

Abstract

Harmful Algal Blooms (HABs) represent a critical environmental, public health, and socio-economic challenge for freshwater ecosystems across India. Driven primarily by anthropogenic nutrient loading, climate change, and altered hydrological regimes, the proliferation of toxic phytoplankton, particularly cyanobacteria, severely degrades lake water quality. This comprehensive analysis explores the multifaceted causes, profound ecological impacts, and localized management strategies for HABs in the context of Indian lakes, such as Dal Lake, Vembanad Lake, Hussain Sagar, and Chilika Lake. Eutrophication, fueled by untreated municipal sewage, industrial effluents, and agricultural runoff laden with nitrogen (NO₃-) and phosphorus (PO₄³-), provides the primary catalyst for explosive algal growth. Consequently, these blooms lead to severe hypoxia, devastating fish kills, and the disruption of complex aquatic food webs. Furthermore, the secretion of potent cyanotoxins, including microcystins and saxitoxins, poses acute health risks to communities relying on these water bodies for drinking, agriculture, and recreation. Given the vast geographical and cultural diversity of India, centralized top-down management approaches often fall short. Therefore, this study emphasizes the necessity of community-level management interventions. By integrating traditional ecological knowledge, low-cost bioremediation techniques like floating wetlands, and active citizen science for early warning monitoring, local populations can effectively mitigate bloom impacts. This paper provides an in-depth synthesis of current research, emphasizing that sustainable lake conservation in India requires a localized, community-driven framework supported by stringent nutrient management policies and continuous scientific monitoring.