Effects of Increased Atomospheric Carbon Dioxide on Coral Reefs


Coral reefs are called the rainforests of the oceans because they provide habitat for a wide variety of marine plants and animals. The rocklike substrate of a coral reef is an accumulation of calcium carbonate, a building material used by humans in limestone and concrete. Calcium carbonate is secreted by tiny reef building animals and plants layer by layer to form coral reefs. These reef building organisms obtain their building materials from sea water in the form of calcium and carbonate ions.

Increased carbon dioxide in the atmosphere, the same phenomenon that brings us global warming, is also changing sea water chemistry with respect to carbonate, thereby decreasing the ability of reef building organisms to secrete calcium carbonate. Many reefs around the world are in decline from overuse and destruction, from warmer sea water temperatures, diseases, eutrophication and bleaching. [Eutrophication is the term used for excess plant production in water leading to, in worst cases, deoxygenated water. Ed.]

Decreasing corals’ ability to build reefs means they are less likely to survive environmental insults and slower to recover if they do survive. We spoke with Joan A. Kleypas about her work on reef communities and the effects of environmental changes on them.

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