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Coral Bleaching

Coral Bleaching. Rebecca Cebulka. What are Corals?. Marine invertebrates that live in colonies Similar to anemones Some can catch small fish and plankton Typically live in deep ocean Most obtain nutrients from symbiotic algae which live in the coral’s tissues Grow in clear, shallow water

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Coral Bleaching

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  1. Coral Bleaching Rebecca Cebulka

  2. What are Corals? • Marine invertebrates that live in colonies • Similar to anemones • Some can catch small fish and plankton • Typically live in deep ocean • Most obtain nutrients from symbiotic algae which live in the coral’s tissues • Grow in clear, shallow water • Form coral reefs

  3. Coral Reefs

  4. What is coral bleaching? • Corals get their color from symbiotic algae • Changes in surrounding water cause stress • Warmer or colder temperatures • More or less light • Stress causes coral to expel algae, leading to bleaching and a lack of food for the coral CHANGES IN WATER COLOR-PRODUCING ALGAE EXPELLED CORAL BECOMES STRESSED

  5. Healthy Coral & Bleached Coral

  6. What Causes Bleaching? • Temperature changes of 1-2°C over several weeks • Increase in T more likely to cause bleaching

  7. What Causes Bleaching? • Solar Radiation • Increased UV radiation(280-400nm) and photosynthetically active radiation (400-700nm) • Corals in shallow waters are more prone to bleaching – coral reefs especially!

  8. Effects of Coral Bleaching • Algae provide necessary nutrients for corals – prolonged bleaching will result in coral death due to lack of food • Destroy ecosystems which are the only home to many species used for both food and medicine

  9. Effects of Coral Bleaching • Destroy reefs that protect shores from the impact of waves and storms • Cut back on economic benefits to local communities from tourism • Becoming more and more prevalent

  10. Other Dangers • Increased carbon dioxide • Raises ocean acidity, preventing coral from building its calcium carbonate skeleton • Won’t kill coral directly, but makes it more difficult to recover from things such as bleaching

  11. Other Dangers • Overfishing • Kills off a main part of the reef’s ecosystem • Some types of fishing involves scraping the ocean floor, ripping up coral

  12. In Summary • Coral bleaching occurs when corals expel symbiotic algae due to changes in the surrounding water • Causes of coral bleaching include increasing water temperature and solar radiation • Increased CO2 in the air is making it difficult for coral to recover from bleaching events. • Death of coral reefs is becoming more and more common and is expected to continue.

  13. References • http://ocean.si.edu/corals-and-coral-reefs • http://www.marinebiology.org/coralbleaching.htm • http://oceanservice.noaa.gov/facts/coral_bleach.html • http://www.onr.navy.mil/focus/ocean/habitats/coral2.htm • http://www.globalissues.org/article/173/coral-reefs

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