Cape Town - Scientists have found a way which may save corals from dying out as a result of global warming – and humans can pitch in and help.
Some corals that live in warmer waters have genetic variations to tolerate warmer seas. Researchers from the University of Texas, Oregon State University and the Australian Institute of Marine Science ran a project where they crossed corals from the warmer waters of the Great Barrier Reef with those that live in cooler seas 500km to the south.
In their findings published in the journal Science the researchers said coral larvae that had parents from the warmer waters, which were about 2ºC warmer, were up to 10 times more likely to survive heat stress compared with those with parents from the cooler southern seas.
“The discovery has implications for many reefs now threatened by global warming, and shows for the first time that mixing and matching corals from different latitudes may boost reef survival,” the researchers said in a statement.
The researchers identified the biological processes responsible for heat tolerance in corals and showed that heat tolerance could evolve rapidly based on existing genetic variation.
University of Texas professor Mikhail Matz said the research showed that corals did not have to wait for new mutations to appear.
“Averting coral extinction may start with something as simple as an exchange of coral immigrants to spread already existing genetic variants. Coral larvae can move across oceans naturally, but humans could also contribute, relocating adult corals to jump-start the process,” Matz said.
Warming of the oceans as a result of global climate change has had a damaging effect on many corals. The effect is known as coral “bleaching”, as the corals lose their colour.
The National Oceanic and Atmospheric Administration (NOAA) in the US says the global ocean temperature has risen by 0.7ºC since the late 19th century and is continuing to climb.
The increasing temperatures stress the tiny algae that live in a symbiotic relationship with corals, inside the polyps’ tissues. These algae supply corals with food and give coral its colour. When the water temperatures are too warm, the algae leave, turning the coral white.
NOAA says while corals can survive bleaching events, they are put under great stress by this and are less resistant to disease, and are subject to mortality.
A World Resources Institute research project estimates that the costs of destroying a kilometre of coral reef ranges between $137 000 (R1.6m) and $1.2m over 25 years – counting the economic value reefs contribute only to fisheries, tourism and shoreline protection.
Cape Times