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Sunday, August 2, 2009

Lakshadweep corals threatened by Global Warming

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The abundant hard corals of Porites species, found in blue water lagoons of Lakshwadweep islands , are facing threat to their existence due to Global Warming , a study by scientists of the National Geophysical Research Institute (NGRI) revealed.

S. Masood Ahmad , head of the paleo- climate group at NGRI, who led the study said that the growth of Porites corals has come down to 1.25 cm per year between 1993 to 2003, which was earlier 2cm per year from 1920 to 1992. He said that the calcification in these corals was reduced since 1993. Increased CO2 and rise in temperature could have caused ocean acidification.

“We are working on past climate changes using hard coral records from Lakshwadweep islands. Basically, we are using carbon and oxygen isotopes to find out sea surface temperature changes and monsoon driven nutrient changes for past 100 years....The annual bands formed on the corals were first studied through X-ray radiograph and the results were corroborated by oxygen isotope data.” Our Studies are conclusive because of the oxygen isotope data,” Dr. Masood was quoted in the report.

He said the results clearly showed that the monsoon driven upwelling had decreased considerably during the 20th century.

The annual mean sea surface temperature (SST) has increased considerably by approximately 0.8 degrees Celcius since 1920 around the Lakshwadweep islands, which is greater than the mean rise in SST of around 0.6 degrees Celcius for the Indian Ocean and 0.5-0.6 degrees for the Global SST.

The decrease in the growth of hard corals in Lakshwadweep was found to be around 25 p.c., studies carried out on similar corals in the Great Barrier Reef of Australia revealed it to be around 14 p.c.

adpated from the original report by Y. Mallikarjun published in The Hindu dtd August 1, 2009

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