Impact of Noctiluca scintillans Bloom on Coastal Fauna of Mandapam Region in Gulf of Mannar Marine Biosphere Reserve, Southeast Coast of Tamil Nadu, India

T. Shunmugaraj, Koushik Sadhukhan, Rameash Chatragadda, M. V. Ramana Murthy


On 11th September, 2019, coastal waters near to offshore islands of Mandapam region appeared in dark green colour, which is caused by bioluminescent dinoflagellate Noctiluca scintillans, commonly called as Sea Sparkle. Extensive monitoring was carried out during 11th to 25th September, 2019 to assess the impact of this bloom on offshore islands of Mandapam region of Gulf of Mannar coastal fauna. Mass mortality of variety of fish, sea shells and sea snakes washed ashore on Kundukal area in Mandapam region was observed due to the sudden raise of Noctiluca scintillans bloom. No negative impact on coral reefs was recorded from Mandapam group of Islands. Reef building corals remain healthy during and after the bloom formation. There is no significant (p value 0.2111, p<0.05) difference was found in the environmental parameters investigated before and after the bloom formation. Nutrient rich environment and favourable environmental parameters might have helped coral symbionts to respond positively which in turn accelerate the density of zooxanthellae without doing any negative effect on coral holobiont and consequently that leads to maintain a healthy reef condition during this bloom formation.


Algal Bloom; Coral Reefs; Fish Mortality; Water Quality


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