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Coral Bleaching

Coral Bleaching. Erica Weston. The Importance of Coral Reefs. Coral reefs are like the rainforests of the sea Biologically diverse Support 33% of marine fish species Provides medicines, chemicals, and other resources. The Importance of Coral Reefs.

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Coral Bleaching

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  1. Coral Bleaching Erica Weston

  2. The Importance of Coral Reefs • Coral reefs are like the rainforests of the sea • Biologically diverse • Support 33% of marine fish species • Provides medicines, chemicals, and other resources .

  3. The Importance of Coral Reefs • Coral reefs attract tourists to island, many of which are impoverished and provide revenue. • Reefs provide a barrier to prevent erosion and protect from storms and floods. • Provided millions of dollars worth of services

  4. What is Coral Bleaching? • Coral reefs get their bright colors from a mutualistic relationship with algae called zooxanthellae. • Zooxanthellae live in the coral and receive shelter and compounds needed for photosythesis. • Corals receive food from the zooxanthellae’s photosynthesis products. • this allows coral to secret calcium carbonate and grow.

  5. What is Coral Bleaching? • The tropical waters that corals grow in are very nutrient poor. • During photosynthesis the algae make oxygen. Corals use oxygen to remove wastes. • Zooxanthellea also provide the coral with glucose, glycerol, and amino acids.

  6. What is Coral bleaching? • When the coral is under stress it will expel it’s zooxanthellae. • This makes the coral appear “bleached” • The coral can no longer build its calcium carbonate skeleton. • Can regain zooxanthellae if stress is reduced. If not, corals can die.

  7. Coral Stressors • What causes coral to expel the zooxanthellea? • Rising water temperatures • Pollution • Overfishing • Natural disasters • Predation • Coral mining • Coral reefs are very fragile habitats.

  8. Pollution and Natural Disasters • The zooxanthellea need light from the sun for photosynthesis. • If pollution causes the water to be cloudy the sunlight cannot reach the zooxanthellea and they cannot produce the byproducts the coral depend on. • Natural disasters can also cause the water to become cloudy with sediment and block the sunlight. • Natural disasters can also tear coral reefs apart and extreme low tides can cause them to dry out and die.

  9. Increased Carbon Dioxide • A study was done (Hii et al. 2009) that tested the effect of increased co2 on two different species of coral. • Porites cylindrica and Galaxea fascicularis • The increased C02 caused stress and reduced zooxanthellae in both species of coral and caused bleaching. • Degree of stress was species dependent.

  10. Temperature and Predation • Corals live in a narrow temperature margin. • A rise in temperature in 1-2 degrees for 5-10 weeks can cause bleaching. • Corals are also venerable to predation from starfish, fish, crabs, worms, and snails. • 1978-1979 outbreak of crown-of-thorns starfish.

  11. Coral mining and Overfishing • The most devastating threat to corals come from humans. • Many coral reefs are harvested for aquarium fish and decoration, jewelry, or building materials. • Certain fishing techniques also kill coral. • Blast fishing • Cyanide fishing • Deep water trawling

  12. Areas of Mass Coral Bleaching

  13. Coral Evolution • The coral expelling their zooxanthellae may be an adaptation so they can acquire different zooxanthellae that can withstand the environmental stress. • Some studies have shown an increased tolerance in certain coral species (Maynard et al. 2008) when comparing the damage from a bleaching event in 1998 and a bleaching event in 2002. • Another study (McClanahan et al 2007) showed that some corals seem to have acclimated to rising temperature and bleach less, though these areas are less diverse.

  14. Coral Evolution • The future of coral reefs will highly depend on how quickly and efficiently they can adapt to global changes. • Although some coral species appear to be evolving a tolerance for higher temperatures and Co2 levels, human interference in reefs by harvesting and fishing still pose a problem.

  15. Protecting Coral Reefs • In 1998 the United States established the Coral Reef Task Force (CRTF) to protect and conserve coral reefs. • The CRTF monitors and maps US coral reefs and researches causes of coral bleaching. They also work on finding ways to prevent bleaching. • To fully protect reefs legal action may be needed such as Marine Protected Areas.

  16. Works Cited • Buchheim Jason. Coral Reef Bleaching. 1998. http://www.marinebiology.org/coralbleaching.htm. April 2010. • Maynard, J. A., Anthony, K. R. N., Marshall, P. A. Masiri, I. 2008. Major bleaching events can lead to increased thermal tolerance in corals. Marine Biology 155: 173-182. • McClanahan, T. T., Ateweberhan, M., Muhando, C. A., Maina, J., Mohammed. M. S. 2007. Effects of climate and seawater temperature variation on coral bleaching and mortality. Ecological Monographs 77: 503-525. • National Oceanic and Atmospheric Administration. March 25,2008 http://oceanservice.noaa.gov/education/kits/corals/coral11_protecting.html. April 2010. • Yii-Siang Hii, Abol Munafi Ambok Bolong, Teng-Teng Yang, and Hock-Chark Liew, “Effect of Elevated Carbon Dioxide on Two Scleractinian Corals: Porites cylindrica (Dana, 1846) and Galaxea fascicularis (Linnaeus, 1767),” Journal of Marine Biology, vol. 2009, Article ID 215196, 7 pages, 2009.

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