2. Environmental Factors Affecting Corals Water Motion Depth: photic vs aphotic zone & water motion Sedimentation Salinity: 32-35 o / oo Temperature: 18-32 o C Tidal fluctuations Nutrients: Eutrophic vs oligotrophic Water Motion Depth: photic vs aphotic zone & water motion Sedimentation Salinity: 32-35 o / oo Temperature: 18-32 o C Tidal fluctuations Nutrients: Eutrophic vs oligotrophic

3.  What is a coral? What is a coral?  Healthy corals accumulate CaCO 3 at rate of 3-15 meters in 1000 years

4.  Predation  Crown-of-thorns starfish (Acanthaster planci): coral predator in Indo-Pacific Reefs  Time lag = cause/effect (max. # of predators as coral level falls)  Removal of the starfish Removal of the starfish Click video

6.  Storm Damage ◦ Hurricanes or tropical storms ◦ Physical breakage of corals ◦ Abrasive sediments  Hurricane Hattie (1961 – Cat 5) destroyed 43 km of the British Honduras barrier reef ◦ Recovery – 25 to 100 years

7.  Exposure to air ◦ Corals dry out ◦ Overheat

8.  Reef erosion = shores/coastal properties are exposed to damages from waves  Artificial reefs: human-made structures = concrete/stone blocks, sacks filled with sand or shipwrecks (sunken ships) ◦ Colonized by algae, corals and fish ◦ Used as submerged breakwater  Dissipate wave energy Click

9.  Prevents erosion of land  Anchorage/protection for harbors  New habitats  Increase fishing areas  Tourism – snorkeling/diving

10.  USS Oriskany (2006)

11.  Geomorphology – study of landforms and processes involved in shaping them

12.  Shows growth and geological history of reef  Carbon Dating – age of coral sample ◦ As corals grow, carbon (from carbon dioxide) is deposited in their skeleton as CaCO 3 ◦ 14C carbon slowly decays to 12C  Proportion of 14C to 12C estimates age of coral  Can estimate age up to 50,000 years old

13.  Deep drilling – cores of material to identify corals and estimate growth rate ◦ Have ‘bands’ just like tree rings (give age)  Evidence of growth rate due to environmental conditions like temperature or nutrient availability

14.  Growth up to 20m deep  Fossil corals found at 1200 m is evidence of subsidence (caving in and sinking of land area) ◦ New coral grow on top of old as reef gradually sinks  Fossil corals found above sea level ◦ Evidence of changes in sea level  Mexico – sea level changes between ice ages

15. Human impacts on coral includes: Aquarium/Souvenir Trade Overfishing Pollution Dredging Coastal Development Tourism Global Climate Change Ozone Depletion

16. Coral Reefs: Human Impact Worldwide disappearance Fishing with explosives Waste oil dumping Sediments Philippines: 75% of the reefs damaged

17. Dynamiting Reef

18. Destructive Resource Extraction Practices

19. Toxic Chemical Spills

20. Sediment Plume Entering the Ocean

21. Corals Smothered in Sediment

22. Dredging

23. Coastal Development

24. Anchor Damage

25. Diver Damage

26. Ecotourism Pennekamp Reef, Key Largo, FL

27. Net Damage

28. Net Entanglement

29. Overfishing and Bycatch

30. Ornamental Trade: Fan worm Threadfin Butterfly fish

31. Introduced Species Acanthophora, Eucheuma, & Gracillaria

32. Feeding Fish

33. Nutrients and Algae Growth Dictyosphaeria cavernosa

34. Bleaching

35. Global Bleaching (2002) none low moderate severe severity unknown

36. Acid Rain in Marine Environment reduces ability of marine organisms to utilize calcium carbonate Coral calcification rate reduced 15-20% Skeletal density decreased, branches thinner

37. Sea Level Rise

38.  Climate Close-up (paleoclimatology) Climate Close-up  Coral Reefs Coral Reefs