1. Coral Reefs Oasis of the Sea Coral Reefs

2. Coral Reefs • Why are coral reefs unique? Coral Reefs

3. Coral Types • Hermatypic • Ahermatypic • Both groups belong to the phylum Cnidaria Coral Reefs

4. Coral Structure & Anatomy Coral Reefs

5. Coral Reproduction Coral Reefs

6. Coral Nutrition • Zooxanthellae provide nourishment for the coral through photosynthesis • Polyps eat and are voracious predators on zooplankton Coral Reefs

7. Other Reef Builders • Corals do not build a reef alone • Coralline algae produces a skeleton of calcium carbonate that grows in hard sheets on the surface of the reef Coral Reefs

8. Conditions Needed For Reef Growth • Temperature • All reefs are bounded by the 20 C isotherm • Optimal reef development occurs at 23-25 C and up to 36-40 C • Water temperature that is too warm will cause coral bleaching • The zooxanthellae is expelled from the coral • El Nino events cause massive bleaching in some areas (1997-98) Coral Reefs

9. Coral Reefs

10. Light • Zooxanthellae dependent corals do not develop in water deeper than 50-70 meters • This limitation occurs due to photosynthetic requirements Coral Reefs

11. Salinity and Sedimentation • Corals are intolerant of salinities ranging outside of 32-35 ppt • Human activities; dredging, mining, logging, and construction increase the amount of sediment and freshwater runoff • Sedimentation clogs feeding mechanism and reduces the penetration of sunlight Coral Reefs

12. Wave Action • Usually not a problem due to hard coral exoskeletons • Benefits: renews oxygen, removes sediment, brings in new plankton • Reefs cannot tolerate extended periods of exposure to air Coral Reefs

13. Fringing Reefs Coral Reefs

14. Barrier Reefs Coral Reefs

15. Atoll Reefs

16. Coral Reef Ecology • Coral reefs are easily the richest and most diverse of all the oceans ecosystems • How do these animals interact with each other, what role do they play in the ecosystem? • Reefs are found in areas that are usually poor in nutrients, lack phytoplankton and other means of primary production • The question is how do these habitats thrive in these nutrient poor waters? Coral Reefs

17. Nutrient Cycling Coral Reefs

18. Competition • Space is a limiting resource • Sessile animals compete for space in interesting ways • Fast growers shade out their neighbors • Some use mesentery filaments or sweeper tentacles to sting neighbors Coral Reefs

19. Predation and Grazing • Predation • Grazing • Grazers are very important to the ecosystem since they help keep the algae in check Coral Reefs