Coral bleaching

Article By:

Heron, Scott F. Coral Reef Watch, National Oceanic and Atmospheric Administration, College Park, Maryland.

Eakin, C. Mark Coral Reef Watch, National Oceanic and Atmospheric Administration, College Park, Maryland.

Last reviewed:January 2022

DOI:https://doi.org/10.1036/1097-8542.161530

The response of corals to environmental stress in which they eject the single-cell algae that live within the transparent coral tissue, making the white coral skeleton visible. Corals (Fig. 1) are animals that live in a partnership (symbiosis) with single-cell plants, specifically, a type of algae called zooxanthellae (genus Symbiodinium). These algae live inside the coral tissue and use sunlight to generate energy through photosynthesis, just as terrestrial (land) plants do. Zooxanthellae provide up to 90% of their coral host's energy requirements. This partnership enables corals to construct the calcium carbonate skeletons that form reefs up to thousands of miles in extent. The complex three-dimensional structure of reefs provides habitat for a wide array of plants and animals, including as much as one-quarter of all ocean fish species. People also benefit from coral reefs; not only do coral reefs provide a supply of fish for human food consumption, but they also (1) protect coastlines from erosion by waves, (2) act as a source for compounds used in new drug discoveries and medical treatments, and (3) provide areas for tourism and related industries. See also: Algae; Coral reef structural complexity; Ecological communities; Ecosystem; Marine ecology; Mutualism; Photosynthesis; Reef; Symbiosis

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