June 23, 2008
By Syed Akbar
Indian marine scientists and oceanographers have successfully repopulated corals in Lakshadweep showing the world that coral reefs can be created artificially.
Using the help of local people trained as scuba drivers, experts at the National Institute of Oceanography, Goa, have artificially grown coral reefs near all the 10 islands in Lakshadweep. Coral reefs in India are present only at two places, Andaman and Nicobar and Lakshadweep and they suffered heavy damage in the last two decades because of human intervention.
"Coral reefs in India have been under stress for quite some time. Lakshadweep reefs bore the brunt of coral mining, souvenir coral collection, ground water pollution and mechanical damage owing to activities like dredging. We involved local people in rebuilding coral reefs in Lakshadweep," Dr MV Moideen Wafar told this correspondent
from Goa.
Corals are distributed below water surface down to 50 m depth, assessment of their well-being and management requires competence in scuba diving and observation skills. Dr Wafar and his team created a dive centre in Lakshadweep, acquired diving kits, trained a broad spectrum of stakeholders ranging from officers, wardens, scientific staff to unemployed local youth.
The scientists then took up transplantation of corals to repopulate damaged coral reef areas. During the last two years the technique has been tested and found suitable. It is also simple enough to be used by the local population with limited or no knowledge of corals.
"I am in the process of transferring this to a community-involved exercise in all islands so that reef restoration is enhanced and additional income generated for the local population by way of fish catch from near the transplantation site," he said.
Repopulating corals is a hectic task as corals grow very slowly. The massive ones like the brain corals grow no more than a cm per year. This is because the calcium carbonate deposition is a slow process and the growth occurs in all directions. The branching corals are relatively fast-growing. Some of them can grow as much as 18 to 20 cm per year but their skeletons are less dense than those of the massive ones.
Unlike the fringing reefs which are common around the islands in the Gulf of Mannar, Gulf of Kachchh, Andaman and Nicobar Islands, the reefs in the Lakshadweep group of islands are oceanic atolls.
During the summer in 1998 a vast layer of warm surface waters spread over the whole tropical region. As a result, the temperature increased by two degrees higher than the seasonal maximum and persisted for several weeks. This was too much for corals. Most of them, in particular the branching corals which are more sensitive, got bleached and died, eventually leaving vast stretches of the reefs barren.
More than 40 countries reported impacts varying from moderate to severe. In India, Andaman and Nicobar reefs were the most severely affected (up to 80 per cent death of corals) followed by Lakshadweep (40 to 80 per cent) and Gulf of Mannar (60 per cent) reefs.
"Our Lakshadweep coral reefs are no more a splendour as was before. In the last three decades we lost lot of our corals, due in part to our own developmental activities and in part to the massive bleaching in 1998. We are left now with reefs that have hardly a quarter of live coral cover - reefs where we could not put our foot down earlier without crushing a coral are now barren for long stretches," Dr Wafar said.
The NIO scientists have been experimenting with growing the corals. The idea is simple, collect fragments of corals, transplant them to secure bases and let them grow in new sites or those sites where they were once luxuriant.
The team carried out initial experiments in the Kavaratti lagoon. The most affected coral general such as Acropora and Pocillopora were selected for this trial. The scientist used 2 x 2 m iron frames with 30 cm high supports and covered with a metal screen. The frames were deployed first at 3 m depth in the lagoon where coral life was totally absent.
Slabs of concrete and coral stones (12 x 12 cm) were used as bases for transplantation. The coral pieces were tied to the bases with thin nylon string and the slabs in turn were secured to the metal screen. Securing the corals to the slabs and the slabs to the frame was done underwater by SCUBA divers in order to minimise stress to the corals. During regular visits, the length of the transplanted coral was measured. In addition, notes were made of the increase in other life forms, like fishes and animals like sea cucumbers, crabs and snails.
In each visit, the frames were cleared of the debris and algal matter. Form the photographs accompanying this article, one can compare how the transplants looked like at the beginning of the experiment and again after 11 months. Besides the formation of several branches, the growth, in terms of increase in length, was of the order of 5-10 cm in Acropora and 2 cm in Pocillopora, with no significant
differences between those secured on concrete and coral stone slabs. There was also no mortality of corals at all during the one year which includes a 4-month monsoon period known for rough sea conditions and low light transparency. This was due to the care exercised in handling the fragments, locating good sites for transplantation and continuous monitoring. What is of further interest is the increase in other biodiversity at the site - several species of fishes besides
holothurians, cowries and snails have colonised the transplantation site.
"We now have a simple technique to increase the coral cover and biodiversity in our reefs as fast as possible. Besides increasing live coral cover, this could also serve tourists who neither swim nor dive and yet would like to see corals at shallow waters. As this technique does not demand high skills, this could be developed into a community venture, generating modest income for local slanders as well as
instilling in them a sense of commitment to coral reef conservation," he said.
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