Coral growth rate dropped by 40pc since 1970's

A new study has found that coral growth rates have plunged 40 percent in since the mid 1970s.

A team of researchers working on a Carnegie expedition in Australia's Great Barrier Reef have suggested that ocean acidification might be playing an important role in the perilous slowdown. They compared current measurements of the growth rate of a section of the Great Barrier Reef with similar measurements taken more than 30 years ago.

In order to establish a cause-and-effect relationship between acidification and decreased calcification, the team led by Carnegie's Ken Caldeira compared measurements of the rate of calcification in one segment of Australia's Great Barrier Reef called Bird Island, that were taken in between 1975 and 1979 to those made at the neighboring Lizard Island in 2008 and 2009.

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

However, the team was not able to demonstrate a change in the amount of live coral covering the reef structure over the three decade period.

If the reef in Australia was as sensitive to ocean acidification, then the increase in ocean acidification would be sufficient to explain the 40 percent decline.

Caldeira said that the coral reefs were getting hammered, and ccean acidification, global warming, coastal pollution, and overfishing were all responsible for damaging them.

The findings are published in Geochimica et Cosmochimica Acta.