The intensity of coral bleaching has increased in the Gulf of Mannar and Palk Bay in May. However, no mortality has been witnessed so far.
While the prevalence of bleaching was less than 3% during April in the Gulf of Mannar, it has increased significantly in May.
During a rapid survey conducted from May 15-23 by the Suganthi Devadason Marine Research Institute, a total of nine reef areas including two reef areas in Thoothukudi group (Vaan, Koswari and Kariyachalli Islands), three in Mandapam Group (Shingle, Krusadai and Hare Islands), three others in Keelakarai group (Mulli, Valai and Thalaiyari Islands) and reefs in Palk Bay were surveyed.
In the Keelakarai group, which was the most affected, the prevalence of bleaching has increased significantly up to 35% (Mulli Island) from 3% in April. In the Mandapam group (Krusadai Island), the bleaching went up from 6% to 28% during the period. Twelve percent of corals have suffered bleaching in Palk Bay.
The high temperature level of 32.1º C in April that caused bleaching, has now simmered down to 30.2º C. “If the temperature level drops further, corals would recover back to normal, and if not, bleaching would undoubtedly lead to mortality,” said J.K. Patterson Edward, Director, Suganthi Devadason Marine Research Institute.
While massive corals were the first to be affected due to elevated temperature, it was followed by branching coral species.
Earlier, the third and longest global coral bleaching from 2014 to 2017 had caused severe coral mortality, following which no mass coral bleaching events were witnessed in 2017 and 2018.
So far in 2019, coral bleaching has been reported in reef regions including Lord Howe Island in Australia, French Polynesian islands of Tahiti and Moorea and Thailand. Closer home, bleaching has been witnessed in the Andaman Sea and the Gulf of Thailand.