Corals or mongas are no strangers to Indians. How many of us have been told by astrologers to wear a monga to change our destiny? The deep orange-ish red stone can be seen on rings and even as pendants on a majority of Indians.

In India, major reef formations are restricted to the Gulf of Mannar, Palk bay, Gulf of Kutch, Andaman and Nicobar Islands and the Lakshadweep islands. Laksha-dweep alone consists of 10 atolls with 36 islands of which 10 are inhabited. The most northern reefs are in the Gulf of Kutch.

Corals are simply calcium secretions formed as a result of algae known as zooxanthellae that live within the coral where they convert energy from the sun into food for coral animals. It is these algae that give the corals their bright hues. These polyps secrete a stony skeleton that forms intricate and delicate looking structures. Coral reefs are important marine ecosystems and can be found even as deep as 1,000 metres below sea level – or even deeper. Coral reefs provide shelter for thousands of brightly coloured fish. Many larger open sea fish leave their young in the protection of corals while they go looking for food.

But for how long will this continue? Corals are under threat. Global warming and deep sea trawling are just two of the many dangers that they face. According to Chennai-ba­sed environmentalist Vinita Hoon’s paper entitled Review of Coral Reefs, sedimentation, dredging and coral mining are damaging near shore reefs, while the use of explosives and bottom nets in fishing are damaging offshore reefs in specific sites. The reefs at the northern and southern ends of the Gulf of Mannar are partially degraded due to human activities (mining, fishing and industrial development); the reefs around the Anda­man and Nicobar Islands faced a serious natural threat in the past two decades with infestation of the crown-of-thorns starfish.

In India, the ministry of environment and forests has been entrusted with the task of developing an action plan to manage the reef resources and issue guidelines for the sustainable utilisation of coral reefs. It is the job of the department of forests and wildlife to monitor, manage and conserve these fragile eco-systems if they fall under a protected area. Yet, most often, these officials have little or no knowledge of coral reef ecology.

Coral reefs are also sensitive to changes in temperature. When the temperature of seawater rises, cor­als start to lose colour in a pro­cess called bleaching. Scientists feel that prolonged periods of excessive sunlight levels, along with higher temperatures of the seawater, cau­se the symbiotic algae to become overactive, causing them to poison the host. The host coral, in order to defend itself, throw algae out into the seawater where they are ble­ached off their colour. With algae gone, the corals have no other means to get food and nutrition and so they become weak and susceptible to damage from storms and disease.

Scientists from the Central Marine Fisheries Research Insti­tute, Cochin, studied the coral vulnerability due to warming of Indian sea reef regions. According to them, Indian coral reefs have experienced 29 widespread blea­ching events since 1989 and 2002. E Vivekanandan, scientist-in-charge of Chennai Research Cen­tre of Central Marine Fisheries Research Institute, who led the study said, “We studied the sea surface temperature prior to, during and after 1998 coral bleaching events in the five regions and fou­nd that coral bleaching occurred when the maximum summer sea surface temperature exceeded 31 degrees Celsius and remained high for more than 30 days.”

Bleaching in 1998 saw an estimated 16 per cent of the world's reefs being destroyed.

In January 2010, the Zoological Society of London (ZSL) listed 10 of the world's most important types of coral, and expressed their fears that all of them would be extinct within 50 years because of a combination of climate change, over fishing, careless tourism and pollution.

Last year in May, seaweed was revealed as a new threat to the already beleaguered corals. A study led by Mark Hay, professor at the Georgia Institute of Technology, US, seaweeds release deadly chemicals when they come in contact with corals. About 70 per cent of the seaweed species studied had harmful effects when they were in direct contact with coral. According to scientists, over fishing is allowing the seaweed to proliferate. Seaweeds are kept in check by plant-eating fish whose populations are reducing drastically as a result of over fishing.

Corals have found an unlikely saviour in the form of parrotfishes, which are found in relatively shallow tropical and subtropical oceans throughout the world, but with the largest species richness in the Indo-Pacific. A study on 18 coral reefs from Mauritius to Tahiti, led by David Bellwood, Terry Hughes and Andrew Hoey, of the Australian Research Council Centre of Excellence for Coral Reef Studies at James Cook University, showed that parrotfishes remove sick and dead corals and clean areas for new corals to settle, remove weedy growth and cart away sand and sediment that would otherwise smother the corals. Unfortunately, parrotfish is fished along with other fishes and if we want the parrotfish to continue to save corals, it is imperative the world realise that fishing them imperils corals.

Another ray of hope is the recent reconstruction work of corals being undertaken in different parts of the world, including Indonesia and the US. The process is a simple one based on electrolysis. A metallic structure fitted underwater to which a weak electric current is passed leads to a buildup of limestone. In an experiment, a few months of this layering of limestone attracted oysters, which came and colonised the entire structure. German architect and marine scientist Wolf Hilbertz was the first to carry out this experiment. He discovered that after a while, corals colonised the limestone structure too, thus leading to hope that corals may not die out after all.

Corals thus formed are supposedly more resistant to high temperatures. This technology is currently being implemented mainly in southeast Asia, the Caribbean, Indian Ocean and the Pacific. With this work, it may be possible to ‘grow’ back coral reefs. But according to experts, although reefs can often recover from bleaching, it leaves the coral vulnerable to damage from storms, infections and other environmental stress, increasing the risk of deaths.

In India, the coastal regulation zone notification, 1991, offers the only legal protection to coral reefs. Government of Tamil Nadu, for instance, has banned the quarrying of massive corals; only dead corals on landward sides can be extracted under a lease.

According to Hoon, norms for regulation of activities within the CRZ state that corals and sand from beaches and coastal water shall not be used for construction and other purposes. Dredging and underwater blasting in and around coral formations shall not be permitted.

The Wildlife Protection Act 1972, amended up to 1991 provides protection of wild animals and certain plants. It is time to bring corals into the ambit of this act as well. zz

(The writer is an environmentalist and former head, Peta, India)