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St. Petersburg Coastal and Marine Science Center

Coral Reef Ecosystem Studies (CREST)

Research: Gallery - Coral Bleaching

When corals are stressed, the symbiosis between the coral animal and its photosynthetic algal symbionts (zooxanthellae) breaks down and the zooxanthellae are expelled from the coral tissue. The zooxanthellae’s photosynthetic pigments contribute much of the color we see in corals, so when the symbionts are lost, the coral’s white calcium carbonate skeleton shows through the thin skin of coral tissue. This lighter or white appearance is referred to as bleaching. Common triggers of bleaching are exposure to very warm or very cold water and changes in salinity. However, many other stressors (for example, excess sediment, nutrients, or chemicals) can also cause bleaching. Bleaching makes corals more susceptible to diseases. If the stress continues, the coral may die. However, if the stress is removed, it is possible for the coral to regain its zooxanthellae and return to normal. Place your mouse over a photo to see a detailed caption including the coral species. Click on a photo to see a larger version. Credit for all photos: USGS/Christina Kellogg.

Bleaching colony of elliptical star coral, Dichocoenia stokesii, Florida Keys.Bleaching colony of elliptical star coral, Dichocoenia stokesii, Florida Keys.
Bleaching colony of elliptical star coral, Dichocoenia stokesii, Florida Keys.
Bleaching colony of elliptical star coral, Dichocoenia stokesii, Florida Keys.Bleaching colony of elliptical star coral, Dichocoenia stokesii, Florida Keys.
Bleaching colony of elliptical star coral, Dichocoenia stokesii, Florida Keys.
Bleaching colony of symmetrical brain coral, Diploria strigosa, Florida Keys. Bleaching colony of symmetrical brain coral, Diploria strigosa, Florida Keys.
Bleaching colony of symmetrical brain coral, Diploria strigosa, Florida Keys.
Bleaching colony of symmetrical brain coral, Diploria strigosa, Florida Keys. Bleaching colony of symmetrical brain coral, Diploria strigosa, Florida Keys.
Bleaching colony of symmetrical brain coral, Diploria strigosa, Florida Keys.
Bleaching colony of lobed star coral, Montastraea annularis, Florida Keys.Bleaching colony of lobed star coral, Montastraea annularis, Florida Keys.
Bleaching colony of lobed star coral, Montastraea annularis, Florida Keys.
Bleaching colony of great star coral, Montastraea cavernosa, Florida Keys.Bleaching colony of great star coral, Montastraea cavernosa, Florida Keys.
Bleaching colony of great star coral, Montastraea cavernosa, Florida Keys.
Bleaching colony of great star coral, Montastraea cavernosa, with polyps extended, Florida Keys. Bleaching colony of great star coral, Montastraea cavernosa, with polyps extended, Florida Keys.
Bleaching colony of great star coral, Montastraea cavernosa, with polyps extended, Florida Keys.
Bleaching colonies of mountainous star coral, Montastraea faveolata, Florida Keys. Bleaching colonies of mountainous star coral, Montastraea faveolata, Florida Keys.
Bleaching colonies of mountainous star coral, Montastraea faveolata, Florida Keys.
Bleaching colonies of mustard hill coral, Porites astreoides, both green and brown color morphs, Florida Keys. Bleaching colonies of mustard hill coral, Porites astreoides, both green and brown color morphs, Florida Keys.
Bleaching colonies of mustard hill coral, Porites astreoides, both green and brown color morphs, Florida Keys.
Bleaching colony of mustard hill coral, Porites astreoides, Florida Keys. Bleaching colony of mustard hill coral, Porites astreoides, Florida Keys.
Bleaching colony of mustard hill coral, Porites astreoides, Florida Keys.
Bleaching colony of massive starlet coral, Siderastrea siderea, Florida Keys. Bleaching colony of massive starlet coral, Siderastrea siderea, Florida Keys.
Bleaching colony of massive starlet coral, Siderastrea siderea, Florida Keys.
Bleaching colony of massive starlet coral, Siderastrea siderea, Florida Keys. Bleaching colony of massive starlet coral, Siderastrea siderea, Florida Keys.
Bleaching colony of massive starlet coral, Siderastrea siderea, Florida Keys.
Bleaching colony of blushing star coral, Stephanocoenia intersepta/michelinii. Bleaching colony of blushing star coral, Stephanocoenia intersepta/michelinii.
Bleaching colony of blushing star coral, Stephanocoenia intersepta/michelinii.
Bleaching colony of blushing star coral, Stephanocoenia intersepta/michelinii. Bleaching colony of blushing star coral, Stephanocoenia intersepta/michelinii.
Bleaching colony of blushing star coral, Stephanocoenia intersepta/michelinii.

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Page Last Modified: December 05, 2016 @ 11:25 AM (JSG)