ECOLOGICAL ASSESSMENT OF CORAL–ALGAL PHASE SHIFTS IN PALK BAY, SOUTHEASTERN INDIA

Abstract

Coral reef ecosystems are undergoing significant degradation worldwide due to a combination of natural and anthropogenic stressors. Key threats include climate change-induced bleaching, coral diseases, pollution, overfishing, and destructive fishing practices. One of the most critical consequences of these stressors is the phenomenon of coral–algal phase shifts, wherein macroalgae replace live corals. While extensively reported in regions like the Caribbean and the Great Barrier Reef, documentation from Indian coastal waters remains limited. This study investigates the occurrence and extent of coral–algal phase shifts along the Palk Bay coast, southeastern India. Using field surveys across three sites—Munaikadu, Thonithurai, and Olaikuda—benthic cover data and biodiversity indices were assessed, alongside nutrient analysis. Our results indicate a significant increase in macroalgal dominance, particularly post-bleaching events, with Munaikadu and Thonithurai exhibiting the highest stress indicators. The findings underscore the role of nutrient enrichment, fishing pressure, and reef zone depth in influencing coral resilience. This study highlights the urgent need for targeted conservation strategies to prevent irreversible reef phase shifts in Indian waters.

KEYWORDS:

Coral Reefs, Palk Bay, Seaweed, Algal Blooms, Macroalgal Dominance