Striking photos of bleached, dying coral

bleached A. tenuifolia_.jpg

Corals are actually made up of many tiny organisms, including the delightfully named photosynthetic algae, zooxanthellae. (Sounds like the name of a space princess, right?)

Unfortunately, zooxanthellae are pretty sensitive to temperature. If the water gets too hot, they die, and all the color goes out of the coral. You can see that happening in this photo, taken off the Atlantic coast of Panama last month as part of documentation conducted by the Smithsonian Tropical Research Institute. Normally, the water where this coral lives is around 82 degrees F (28 C or 301.15 kelvin for the pedants). But, currently, the coasts of Panama and Costa Rica are in the midst of a warming event that's driving temperatures up to almost 90 F (32 C, 305.15 K). Bad news for zooxanthellae.

And bad news for the coral. Bleaching is the first step in a process that leads nowhere good.

Bleaching impairs vital functions of the coral such as reproduction and growth. With prolonged warming, corals begin to die releasing great quantities of mucous resulting in increasingly turbid waters. Oxygen levels may fall as bacteria and fungi proliferate. Anoxic conditions affect fish and coastal productivity.

See more photos, and read about the ongoing documentation.

Photo: Raphael Ritson-Williams, Smithsonian Marine Station