Community responses

Glob. Chang. Biol. http://doi.org/brg5 (2016)

Credit: NATURE PICTURE LIBRARY / ALAMY STOCK PHOTO

Climate change threatens reef growth most notably by increasing temperatures and ocean acidity. Because scleractinian corals vary in their sensitivity to these factors, species composition might be expected to influence reef community response under climate change. However, projections of reef growth under climate change typically neglect this nuance.

To begin to fill this knowledge gap, Remy Okazaki from University of Miami, USA, and co-workers investigate the calcification of twelve Caribbean coral species under a variety of combined temperature and CO₂ partial pressures (p_CO2), an indicator of acidification. They then estimate community-level scleractinian calcification responses for Florida Keys' reef composition under projected climate conditions.

Under a business as usual emissions scenario they find that three of the four most abundant species have negative calcification responses to both elevated temperature and p_CO2. Reefs abundant in these species have projected end-of-century declines in scleractinian calcification of >50%. A fourth common species, Siderastrea siderea, is insensitive to both drivers tested: consequently, reefs dominated by this species have more stable growth rates. These findings support the importance of species composition in determining community responses to climate change.