Coral Reefs Codexery

Coral bleaching

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When corals expel the symbiotic algae living in their tissues and lose their photosynthetic pigments, they turn white.[1] Climate change-driven increases in ocean temperature are the primary trigger for coral bleaching.[1]

Biology and range

The corals that form great reef ecosystems depend on symbiotic algae-like protozoa called zooxanthellae that live within their tissues.[2] As the zooxanthellae provide up to 90 percent of the coral's energy needs, after expelling, the coral may begin to starve.[3] Coral can survive short-term disturbances, but if conditions persist, the coral's chances of survival diminish.[3] In tropical waters that are clear and low in nutrients, the zooxanthellae supply the coral with food generated through photosynthesis.[2]

The symbiotic relationship between coral and zooxanthellae can break down due to adverse environmental conditions, such as unusually warm or cool water temperatures.[4] Research by D.J. Smith and colleagues suggests that photoinhibition plays a role in causing coral bleaching.[4] Recovery from a bleaching event requires the zooxanthellae to re-enter the coral polyp's tissues.[5]

What the specialist sources record

NOAA’s Coral Reef Conservation Program focuses on resilience-based management to sustain valuable ecosystem services.[6] According to Readfearn, reefs in at least 82 countries and territories have been exposed to enough heat to turn corals white since January 2023.[7] The Guardian article notes that across Florida, an average of one in five corals were lost during this event.[7] The DAR report noted that on the Kona coast, an average of 40% of live coral was bleached in many survey locations.[8]

References

  1. Wikipedia, "Coral bleaching" (CC BY-SA 4.0), which cites: US Department of Commerce, "What is coral bleaching?", oceanservice.noaa.gov; US Department of Commerce, "What is coral bleaching?", oceanservice.noaa.gov; "CORAL BLEACHING – A REVIEW OF THE CAUSES AND CONSEQUENCES"; "Understanding Coral Bleaching: Causes, Effects, and Solutions", Great Barrier Reef Foundation; US Department of Commerce, "What is coral bleaching?", oceanservice.noaa.gov; "What is Coral Bleaching and What Causes It - Fight For Our Reef", Australian Marine Conservation Society; US Department of Commerce, "What is coral bl en.wikipedia.org
  2. Wikipedia, "Coral bleaching" (CC BY-SA 4.0), which cites: Berkelmans, "The role of zooxanthellae in the thermal tolerance of corals: a 'nugget of hope' for coral reefs in an era of climate change", Proceedings of the Royal Society B: Biological Sciences, 2006-09-22, p. 2305–231 (original not read by us) en.wikipedia.org
  3. Wikipedia, "Coral bleaching" (CC BY-SA 4.0), which cites: Hoegh-Guldberg, "Climate change, coral bleaching and the future of the world's coral reefs", Marine and Freshwater Research, 1999, p. 839–66; Bollati, "Optical Feedback Loop Involving Dinoflagellate Symbiont and Scleractinian Host Drives Colorful Coral Bleaching", Current Biology, July 2020, p. 2433–2445.e3; "CORAL BLEACHING – A REVIEW OF THE CAUSES AND CONSEQUENCES" (we also read that source) en.wikipedia.org
  4. Wikipedia, "Coral bleaching" (CC BY-SA 4.0), which cites: Lesser, "Coral Reefs: An Ecosystem in Transition", Springer, 2010, p. 405–419; Smith, "Is photoinhibition of zooxanthellae photosynthesis the primary cause of thermal bleaching in corals?", Global Change Biology, 2005, p. 1 (we also read that source) en.wikipedia.org
  5. Wikipedia, "Coral bleaching" (CC BY-SA 4.0), which cites: "Seasonal mesophotic coral bleaching of Stylophora pistillata in the Northern Red Sea", PLOS ONE, 15 January 2014 (original not read by us) en.wikipedia.org
  6. "CORAL BLEACHING – A REVIEW OF THE CAUSES AND CONSEQUENCES". facts only, no text reused. coris.noaa.gov
  7. Readfearn, "More than 80% of the world's reefs hit by bleaching after worst global event on record", The Guardian, 2025-04-23. facts only, no text reused. theguardian.com
  8. "11/5/19 – CORAL BLEACHING NOT AS SEVERE AS PREDICTED BUT STILL WIDESPREAD; Extensive Surveys Show Bleaching Event Now Abating", dlnr.hawaii.gov. facts only, no text reused. dlnr.hawaii.gov

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Coral bleaching (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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