Natural Selection Favors Corals Vulnerable to Climate Change

Live corals are the most important contributors to the structure of the saltwater reef in nature as well as in reef aquariums. Corals, sponges and seaweeds cover most of the surface of coral reefs and make up the most diverse range of all marine ecosystems, as well as account for perhaps one quarter of all ocean species found in reefs.

A recent study from researchers at the University of Hawaii-Manoa, the Joint Institute for Marine and Atmospheric Research (JIMAR) and the National Oceanic and Atmospheric Administration (NOAA) looks at how global changes in climate and ocean chemistry affect corals scarcity or abundance, with wide distributions that affect many.

The researchers examined both the geologic record of past extinctions and recent major events in order to assess the characteristics of dominant corals under various conditions. It was determined that during various growth periods, natural selection favors corals with traits that make them more vulnerable to climate change.

The study notes the following regarding the last 10 thousand years of corals and how it has been particularly beneficial for the species: "Acropora species, such as table coral, elkhorn coral and staghorn coral, were favored in competition due to their rapid growth. Their advantageous rapid growth may have been attained in part by neglecting investment in few defenses against predation, hurricane, 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 believe that the condition which may cause excess carbon dioxide in the ocean could potentially cause mortality at rates that are independent of coral abundance. This density-independent morality and psychological stress may cause the species to decline at a more rapid rate across a broad range of geographic regions.

Yet researchers hope that by more directly addressing this global issue, they can get a better handle on local problems regarding coral conservation.

More information regarding the study can be found here.