1. DescriptionDescription Coral ecology and symbiosisCoral ecology and symbiosis ThreatsThreats Class 38 CORAL REEF COMMUNITIES

2. Diverse and productiveDiverse and productive Thousands of invertebrate and vertebrate speciesThousands of invertebrate and vertebrate species “Rainforests” of the marine world“Rainforests” of the marine world

9. Coral Reef

10. Related to Jellyfish and Sea AnenomesRelated to Jellyfish and Sea Anenomes Colonies; individual polyps with tentaclesColonies; individual polyps with tentacles -predators and filter feeders. Coral animal -- dominant reef-builder

12. Individuals secrete supporting "cup" of CaCO 3 (grow up to 10 cm per year!) Variety of growth forms --Variety of growth forms -- massive, columnar, branching, etc. Coral animal -- dominant reef-builder

15. T: >18˚C…..23-25˚ is best --> mostly low latitude, mostly low latitude, < 30˚ N or S Environmental requirements of growing coral reefs: growing coral reefs:

16. T: >18˚C…..23-25˚ is best --> mostly low latitude, mostly low latitude, < 30˚ N or S Salinitycannot be low (e.g., near rivers) Depth: Photic zone only, cannot grow deeper than 50-150 m Clear water (little suspended sediment, phytoplankton) Environmental requirements of growing coral reefs: growing coral reefs:

17. Symbiotic algae provide much food Tentacles capture additional food Coral Nutrition

18. Zooxanthellae are dinoflagellates (photosynthesis)... give corals color (pink, purple, green)... corals grow only in photic zone Symbiosis: Zooxanthellae get from corals: constant, protected environmentconstant, protected environment source of CO 2 and nutrients (P, N)source of CO 2 and nutrients (P, N) Zooxanthellae give to corals: Food (sugars; they are not eaten)Food (sugars; they are not eaten) O 2O 2 Symbiotic zooxanthellae in corals

21. Types of coral reefs: Fringing reef -- borders shoreline Barrier reef -- further offshore, lagoon in between Atolls -- ring-shaped

27. 1.Natural predators (e.g., crown of thorns star fish) Coral reefs in trouble

28. 2. Human activities (nutrients, fishing, recreation) Coral reefs in trouble Cyanide Fishing

29. Coral ecosystems well suited for low nutrient levels (P and N) Nutrients can come from sewage and fertilizer Coral reefs and nutrients

30. Coral ecosystems well suited for low nutrient levels (P and N) Nutrients can come from sewage and fertilizer Increased nutrient levels allow other species to dominate (e.g., phytoplankton) Ecosystem changes, slow-growing corals can’t compete, or are attacked by disease Coral reefs and nutrients

31. 3. Coral bleaching: zooxanthellae expelled Most common in unusually warm waters: >32˚C 2 degrees above normal maximum causes it Result of global warming? Coral reefs in trouble

32. Blue=low threat, yellow= med., red= high