The team of scientists from the University of Hawaii - Manoa (UHM), Joint Institute for Marine and Atmospheric Research (JIMAR) and the National Oceanic and Atmospheric Administration (NOAA) evaluated both the geologic record of past extinctions and recent major events to assess the characteristics of dominant corals under various conditions.
They determined that during periods advantageous to coral growth, natural selection favors corals with traits that make them more vulnerable to climate change.
The last 10 thousand years have been especially beneficial for corals. Acropora species, like table coral, elkhorn coral and staghorn coral, were favored in competition due to their rapid growth.
This advantageous rapid growth may have been attained in part by neglecting investment in few defenses against predation, hurricanes, or warm seawater.
Acropora species have porous skeletons, extra thin tissue, and low concentrations of carbon and nitrogen in their tissues.
The abundant corals have taken an easy road to living a rich and dominating life during the present interglacial period, but the payback comes when the climate becomes less hospitable.
Researchers from the UHM School of Ocean and Earth Science and Technology (SOEST); the National Marine Fisheries Service (Southeast Fisheries Science Center, Northwest Fisheries Science Center, and Pacific Islands Fisheries Science Center); NOAA National Ocean Service; and NOAA Coral Reef Watch propose that the conditions driven by excess carbon dioxide in the ocean cause mortality at rates that are independent of coral abundance.
This density-independent mortality and physiological stress affects reproductive success and leads to the decline of corals.