mumbai

Updated: Jun 16, 2017 17:04 IST

The state government and an NGO in the city have been trying to protect coral reefs off the Indian coast.

While the state’s focus has been on reviving the Sindhudurg corals, Reefwatch Marine Conservation has been working on those near the Andaman and Nicobar islands.

Coral reefs are considered to be rainforests of the ocean because of the wide variety of marine life they sustain. Reefs are, however, threatened by the rising ocean temperature. Global warming poses a major threat to the corals off the Indian coast.

“The rising temperature of the oceans pose a major threat to the reefs as the ideal temperature for them to survive is between 20 and 26 degrees Celsius. But, the water around the Indian subcontinent, especially the Andamans, is about 28 degrees Celsius,” said Nayantara Jain, who heads Reefwatch. “Any further rise in temperature could be a problem for corals,” she said.

Jain, who has been diving for over a decade, said that she had seen how the reefs were deteriorating.

Coral reefs are formed by a symbiotic relationship between an algae and a polyp — a creature related to the jelly fish. While the algae makes food, the polyp protects it and creates a calcium base for it to grow. Over years, this base grows in size and becomes a coral reef.

“Continuous rise in temperature damages the relationship between the algae and the polyp, which results in them breaking. As a result, the reefs, which get their colour from the algae, weaken, turn white and can die,” said Jain. “The structure shelters small marine animals, which attracts larger animals that prey on them. So, a large number of marine lives depend on coral reefs,” she said.

Jain has been trying to encourage and speed up the growth of reefs off the Indian coast. She and members of Reefwatch rescue broken pieces of coral reefs and restore them to a point, from which they can grow again.

“These fragments can grow back if replanted and taken care of,” said Jain. This, however, is not the only way to protect the reefs.

Fan coral off the Indian coast. ( Sumer Verma )

he Maharashtra government’s mangrove cell and United Nations Development Programme (UNDP) have in three years successfully rehabilitated 2,620 coral fragments off the Malvan coast in Sindhudurg. This was an attempt to revive and facilitate growth of corals and formation of coral reefs.

“We have been using coral fragments from donor colonies to increase their numbers in Sindhudurg,” said Rohit Sawant, project management specialist and marine biologist.

The corals were transplanted in two phases — in December 2015 and April this year — and all of them are growing healthily, said Sawant.

“We take the fragments and attach them to concrete frames with the help of nylon threads. We leave it on ocean beds, at a depth suitable for its growth. Each frame holds about 10 corals,” he said. Around 3,200 coral fragments have been cultivated under the programme so far.

The corals on the first day of transplantation. ( UNDP )

Even though corals grow at the rate of 1.5cm per year, the officials have already seen positive developments already. “The ones rehabilitated in the first phase have developed growth rings. They are similar to the rings that we see on tree barks that indicate their age. This also means that the corals have adapted to the environment and are growing healthily” said Sawant. The project was funded by Global Environment Facility.

The corals after one year of transplantation. ( UNDP )

Suganthi Devadason Marine Research Institute (SDMRI) in Tamil Nadu has been helping the project with their expertise as they have been rehabilitating corals since 2002.

“During our attempts, we realised that rehabilitated corals survive only if they are taken from healthy colonies,” said JK Patterson Edward, director of the institute.

He also said that coral fragments taken from one place must be transplanted in another with the same environmental factors.

Speaking about the challenges that they faced, Edward said that rising ocean temperatures is a major threat to coral reefs. “The overall survival rate was over 80%, but it came down to 45% to 50% in 2010 and 2016 because of increase in ocean temperatures,” he said.

“Using concrete frames to rehabilitate corals is a low-cost but effective method. As the corals slowly try to develop into reefs, there has been an increase in the population of fish in the area,” added Edward.

However, the rehabilitated corals off the Tamil Nadu coast are thriving now and the team in Maharashtra is trying to follow their footsteps. “Though our corals in Malvan are young, we hope that they can gradually develop into reefs like the ones in Tamil Nadu,” said Sawant.

Marine scientist Vishal Bhave from BHNS which has partnered with the programme said that the next step would be to ensure that all the coral fragments survive the next 18 months. “We will monitor the corals for 18 months and in case any of them die, we will replace them,” he said.