Washington, Sep 18 (IANS): In a disturbing trend, a team of researchers has documented that coral growth rates have plummeted 40 percent since the mid-1970s.

The scientists working on Carnegie Mellon University's expedition to Australia's Great Barrier Reef suggest that ocean acidification may be playing an important role in this perilous slowdown.

"Coral reefs are getting hammered. Ocean acidification, global warming, coastal pollution and overfishing are all damaging coral reefs. Coral reefs have been around for millions of years, but are likely to become a thing of the past unless we start running our economy as if the sea and sky matters to us very soon," cautioned Ken Caldeira from the Carnegie Mellon University.

Coral reefs are havens for bio-diversity and crucial for the economies of many coastal communities.

But they are very sensitive to changes in ocean chemistry resulting from human activity.

Coral reefs use a mineral called aragonite, which is a naturally occurring form of calcium carbonate, CaCO3, to make their skeletons with the help of a process called calcification.

During the study, the team compared current measurements of the growth rate of a section of Australia's Great Barrier Reef with similar measurements taken more than 30 years ago.

In order to establish a causal relationship between acidification and decreased calcification, the team compared measurements of the rate of calcification in one segment of Australia's Great Barrier Reef taken between 1975 and 1979 to those made at the neighbouring Lizard Island in 2008 and 2009.

The rates of reef calcification were 40 percent lower in 2008 and 2009 than they were during the same season in 1975 and 1976, found the study.

The study appeared in the journal Geochimica et Cosmochimica Acta.