Study Shows Some Coral Trying to Adapt to Climate Change
A new study led by the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science discovered that mountainous star coral—found in Florida and the Caribbean—can adapt to high water temperatures and acidity conditions. This could say coral reefs may yet survive some of the short-term impacts of global warming on the oceans.
The researchers exposed two threatened Caribbean reef-building coral species, staghorn coral and mountainous star coral, to combinations of normal (26 degrees Celsius) and elevated temperature (32 degrees Celsius) and increased carbon dioxide levels (ph 7.8/800 ppm) for nine weeks. Genetic and physiological data such as skeletal growth was then collected on the corals to determine if stress events are recorded in a coral's skeletal history.
The researchers found that the staghorn coral was more sensitive to heat stress. It experienced 100 percent mortality after 25 days at the elevated temperature of 1.5 degrees Celsius above the historical maximum monthly mean temperature for the Florida Keys. South Florida waters could begin to experience hot spells of this intensity and duration once every five years by 2035, which according to the researchers suggests that the species could become increasingly rare within 20 years.
The mountainous star coral survived 62 days at the elevated temperature and quickly recovered when temperature was reduced at the end of the experiment. Reduced ph did not affect survival but did significantly impact growth under normal temperatures.
"Based on these results we predict that mountainous star coral will very conservatively be able to tolerate any warming the Florida Keys is likely to experience now until 2060 and very possibly to the end of the century," said Chris Langdon, lead researcher and author on this study.
Coral reefs are especially vulnerable to climate change because they are easily affected by warm water. When ocean temperatures rise, the algae that give coral its bright colors leave their host, causing it to look white, a condition known as 'coral bleaching'. The loss of algae, which provide coral with much of its energy, make corals vulnerable to starvation and disease.
The mountainous star coral had special algae, called D symbionts, which the researchers believe made it able to adapt to the experimental climate change conditions.