THOOTHUKUDI The Hindu 26 May 19;
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.
Coral reefs in the Gulf of Mannar suffer mass bleaching as temp rises
Times of India 27 May 19;
Madurai: The coral cover in the Gulf of Mannar (GoM), an important aspect of the marine ecosystem, is under threat yet again as the soaring summer temperature has led to coral bleaching. It should be noted that in 2016, GoM experienced a rampant mortality of corals due to severe bleaching, which had led to the depletion of the coral reef cover from around 39% in 2015 to 23% in 2016. Since then, the depleted reef cover was slowly recovering until the bleaching started again a month ago.
Bleaching was observed in the second week of April by the Reef Research Team (RRT) of Suganthi Devadason Marine Research Institute (SDMRI) in Tuticorin. The team has been continuously monitoring the situation since then. “The intensity of bleaching was comparatively low in April, but it increased this month,” scientist and assistant professor at SDMRI K Diraviya Raj said. He mentioned that in the islands around Tuticorin, the rate of bleaching was less than 3% during April but increased to 12% in May. In Keelakarai (in Ramanathapuram district) group of islands, it saw a rise from 3% in April to 35%. In Mandapam (in Ramanathapuram district) group, coral bleaching was around 6% during April, but it went up to as high as 28% in May. At Palk Bay, the rate of coral bleaching was 12%.
Though there is heavy bleaching, no mortality has been witnessed so far. The corals are in the risk of bleaching when the surface temperature of the sea crosses 30°C. It was the high temperature of 32.1°C in April that caused widespread bleaching in GoM, but winds brought down the temperature by 2°C in the past few weeks. “It is hoped that the temperature will dip further and corals would recover back to normalcy. But if the temperature lingers on higher levels, corals in GoM are likely to suffer from another episode of mass mortality,” Diraviya Raj said.
While global warming is the most important reason for coral bleaching, at GoM, experts said that coral mining and destructive fishing practices are the cause of coral degradation in the area. The total reef area at GoM is 110 square km.
Coral reefs form an ideal habitat for several commercially-important fishes including snappers, groupers, and shrimps. They also form an ideal place of breeding for fishes. Experts said that coral bleaching causes adverse effects to the marine ecosystem and also significantly affect the fishing community around GoM as well. ","tn":"text"},{"tn":"br"},{"value":"“Corals are the main source of productivity for fishing villages along GoM. If corals are affected, it would directly lead to the decrease in fish population,” senior scientist, Council of Scientific and Industrial Research - Central Electro Chemical Research Institute (CSRI-CECRI) J Ravindran told TOI. He said that more than bleaching it was its ‘secondary effect’ (poor quality of water and pollution) that poses bigger threat to the corals. “The secondary effect is nothing but the growth of algae over corals, which leads to the mortality of the latter. This is due to poor ecological conditions,” Ravindran added.
Experts said that ideal coral cover would mean that the impact of tsunami would be significantly less, as the corals serve as natural barriers. They also claimed that coral reefs are important sources of medicines to treat cancer and other diseases.
