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