Coral reefs could start to
dissolve before 2100 as man-made climate change drives acidification of the
oceans. Acidification will threaten
sediments that are building blocks for reefs. Corals already face risks from
ocean temperatures, pollution and overfishing.
“Coral reefs will transition to net dissolving before end of century,”
the Australian-led team of scientists wrote in the US journal Science. “Net dissolving” means reefs would lose
more material than they gain from the growth of corals. Carbon dioxide, the main man-made
greenhouse gas, forms a weak acid in water and threatens to dissolve the reef
sediments, made from broken down bits of corals and other carbonate organisms
that accumulate over thousands of years, it said.
The sediments are 10 times more vulnerable to acidification than the
tiny coral animals that also extract chemicals directly from the sea water
to build stony skeletons that form reefs, the study said. Coral animals will be able to keep growing and replenish reefs long
after sandy sediments start to dissolve, lead author Bradley Eyre, of
Southern Cross University, told Reuters.
“This probably reflects the corals’ ability to modify their environment
and partially adapt to ocean acidification whereas the dissolution of sands is
a geo-chemical process that cannot adapt,” he wrote in an e-mail. The
report said it was “unknown if the whole reef will erode once the sediments
become net dissolving” and whether reefs “will experience catastrophic
destruction” or merely a slow erosion.
Some reef sediments were already
starting to dissolve, such as at Kaneohe Bay in Hawaii, where other pollutants
were contributing. Eyre said it was unclear if the dissolution of sediments
could be a long-term threat to entire islands, from the Pacific to the
Caribbean. Other studies say that deep
cuts in greenhouse gas emissions can limit acidification.
Most studies show that acidification will be overwhelmingly bad for
ocean life, also threatening creatures such as oysters, lobsters and crabs.
Another study however found that it might help the growth of some plants.
“An increase of carbon dioxide in the ocean theoretically could stimulate
higher growth of kelp and seaweeds,” Kasper Hancke, a biologist at the
Norwegian Institute for Water Research, wrote in a statement.
Credit: Indian Express Research
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