Coral reefs can help earthquake prediction: Study

Tuesday, 20 January 2009 10:08

Analysis of coral reefs in the Indian Ocean show that they have annual growth rings, and if previous cycles are a guide, a large Sumatran earthquake could be a possibility in the next two decades, writes Radhakrishna Rao

Coral reefs that constitute an important component of the marine ecosystem could be a reliable indicator to predict earthquakes, says a recent study. A detailed analysis of the coral reefs in the Indian Ocean has revealed that they feature annual growth rings, similar to tree rings, which record cyclical events including seismic activities and tectonic shifts.

According to Kerry Sieh, Professor at Tectonics Observatory of the California Institute of Technology (Caltech) who studies coral reefs around the waters of Sumatra region in Indonesia, “if previous cycles are a reliable guide, we can expect one or more very large Sumatran earthquakes within the next two decades.” Sieh and his team of researchers believe impending earthquakes could be similar to the tsunami that left 2,30,000 people either dead or missing across Asia. “When earthquakes push the sea floor upwards, lowering local sea level, the corals can’t grow upwards and grow outward instead,” say researchers.

Earlier, research studies had gone to show that coral reefs not only protect the coastline from sea erosion and tidal storms, but also help build beaches in low lying islands. Coral reefs also serve as a prolific fish breeding ground accounting for 12 per cent of the global fish yield. Further, they form an ideal habitat for turtles, shrimps, lobsters, sea urchins, algae and a host of other marine life forms.

Slowdown in coral reefs

In a disturbing development, marine scientists have reported that the growth of coral reefs in Australia’s Great Barrier reef has suffered “severe slowdown” since 1990. Marine researches who studied the growth of 328 coral reefs that make up the 1250-mile long Great Barrier Reef, off north-east Australia point out that this development could threaten a variety of marine eco systems.

Researchers say the carbon dioxide in the depths of the ocean get transferred into an acidic state, that in turn makes it more difficult for corals to grab minerals they need to build their skeletons from the sea water. A large spread of coral reefs was destroyed in 1998 when a vast sheath of warm water covered the tropical seas, pushing the average temperature by two degrees centigrade.

“While the impact of the tsunami on corals in India was modest, corals here get bleached due to sedimentation, increase in water temperature and coastal development,” says Rodrigues Sudarshan of the Coastal and Marine Development Programme at the Bangalore-based Ashoka Trust for Environment and Ecology. According to M Wafar, a senior scientist at the Goa-based National Institute of Oceanography (NIO), the Lakshadweep reefs bore the burnt of coral mining, souvenir collection and ground water pollution.

Because of their high degree of productivity, coral reefs are often referred to as “rainforests of the sea.” Studies have shown that coral reefs produce more organic matter per unit than any other eco system. In Asia, coral-based fisheries provide 25 per cent of fish varieties.

The unregulated growth of tourism in SE Asian countries, indiscriminate fishing activities, ornamental fish thriving in the tropical seas and steady build-up of global temperature are taking a heavy toll on these reefs.

In countries like Maldives, coral reefs serve as a major tourist attraction because of their stunning colours and varieties. The massive influx of tourists to Maldives is known to have played a key role in damaging its coral reef wealth. In Philippines, coral reefs are mainly disturbed by the unsustainable collection of ornamental fish varieties which has a big export market.

Meanwhile, in a development of significance, NIO scientists have succeeded in recovering coral reefs in Kavarati island in Lakshadweep through the process of coral transplantation. This will soon be extended to Agati and Kadmat islands.


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