Environmental Factors Affecting Corals and Coral Reefs

1. Environmental Factors Affecting Corals and Coral Reefs

2. Environmental Factors Correlated with Healthy Reef Coral Growth • Warm tropical water • Normal seawater salinity • Appropriate solar radiation • Low organic nutrients (oligotrophic) • Low turbidity • Low sedimentation • Vigorous water motion

3. The Electromagnetic Radiation Spectrum Only green and blue wavelengths pass through water a great distance.

4. Photosynthetically Active Radiation PAR (i.e., visible light)

5. Primary Production Limitations • light • water • nutrients Photosynthesis Photic Zone No Photosynthesis Aphotic Zone

6. Light Absorption in the Ocean Light Intensity • decreases with depth • 100 meter = depth limit of hermatypic corals primarily a result of the overall reduction in light • many studies have focused upon how changing light intensities with depth affect the photosynthesis of zooxanthellae of corals

7. Light Penetration in the Ocean

8. Primary Productivity The rate of production of organic matter by autotrophs

9. Primary Productivity Photosynthesis • Involves the use of light energy in the conversion of inorganic carbon into organic carbon.

10. Photosynthesis 6H2O + 6CO2 + light  C6H12O6 + 6O2

11. Primary Producers Common Name Blue-green algae (cyanobacteria) Red algae Brown algae Green algae Coccolithophorids Dinoflagellates Diatoms Seagrass

12. Primary Productivity Chemosynthesis • Involves the use of energy released by the catalysis of certain inorganic reaction to convert inorganic carbon into organic carbon.

13. Cellular Respiration C6H12O6 + 6O2 6H2O + 6CO2 + energy

14. R=P

15. Measuring Primary Productivity in the Ocean Standing Crop Estimates • weigh out total plant material • measure concentration of chlorophyll in the water • use satellite imagery Measure Actual Rates of Primary Productivity • measure oxygen production and consumption by plants (e.g., light-dark bottle technique)

16. Table 1. Average net primary production and biomass of aquatic habitats. Data from R.H. Whittaker and G.E. Likens, Human Ecol. 1: 357-369 (1973).

17. Primary Productivity Gross Primary Productivity (GP) • The rate of production of organic matter from inorganic materials by autotrophic organisms Respiration (R) • The rate of consumption of organic matter (conversion to inorganic matter) by organisms. Net Primary Productivity (NP) • The net rate of organic matter produced as a consequence of both GP and R.

18. Primary Productivity NP = GP + R Note that R is a negative value because it results in the reduction of organic matter.

19. Plankton Sampling

21. Plankton Size • Picoplankton (.2-2 µm) • Nanoplankton (2 - 20 µm) • Microplankton (20-200 µm) • Macroplankton (200-2,000 µm) • Megaplankton (> 2,000 µm) microplankton picoplankton nanplankton

22. Plankton Sampling Mesh 5 in Collecting bottle Avoidance ability- this is a function of reactive distance, radius of net, speed of tow, burst of speed of larvae To reduce net clogging: • pick correct mesh size • use longer net • tow at slower speeds • tow for shorter time • change configuration of net • Picoplankton .2-3um • Nanoplankton 2-20um • Microplankton 20-200um

23. Rates of primary production regulated by LIMITING FACTORS: • major limiting factors in ocean (inorganic nutrients, light) differ from those on land (moisture, temp, inorganic nutrients, light) • primary production measured via change in O2 concentrations in “light” and “dark bottles”

24. Phytoplankton Zooplankton

25. zooplankton phytoplankton decomposition Light & Dark Experiments Photosynthesis: light + 6CO2 + 6H2O C6H12O6 + 6O2 Respiration: C6H12O6 + 6O2 6CO2 + H2O + ATP

26. light bottle photosynthesis + respiration dark bottle respiration weight

27. Sources of Error • Respiration rates are not equal between light and dark bottles. • The glass wall of the light bottle filters light. • The bottle may not be representative of the water as a whole.

28. Photoadaptation in Corals Changes in pigment concentrations and algal densities in response to light intensity A coral (Acanthastrea) under high magnification. Focus stack. Fluorescent pigments emphasized with full-spectrum lights

29. Colony Morphology Responses to Irradiance Hemispherical Branching Colonies Plate-Forming Colonies

30. Absorption of Ultraviolet Radiation by the Earth’s Atmosphere

31. Types of UV and Human Sunburn Responses

32. Effects of UV on Living Things • damage to DNA resulting in mutations • damage to other biological molecules • proteins: enzyme inactivation • lipids: disruption of cell membranes and membrane transport systems

33. Corals and UV Radiation • decreased growth • decreased rates of calcification • transplantation experiments (deep corals brought to the surface) demonstrate corals may be UV-sensitive (exhibit bleaching and increased mortality) • coral sperm appears to be UV-sensitive (note spawning normally takes place at night)

34. Ultraviolet Absorbing Compounds in Corals • mycosporine-like amino acids (MAA’s) • MAA’s apparently produced by zooxanthellae but stored in the animal tissues • concentrations greater in shallow water corals than in deeper ones • transplantation experiments demonstrate adaptational changes in pigment concentrations • positively buoyant eggs exhibit higher concentrations of pigments than do negatively buoyant eggs

35. Effects of UV on the Coral-Zooxanthellae Symbiosis PAR + UV MAAs PAR PAR Coral pigment Photosynthesis

36. Ozone in the Atmosphere

37. The hole in the ozone Oct. 1979 Sep. 2013

38. Temperature • Lethal Limits • <17 and > 33oC for extended periods of time • physiological effects = bleaching (expulsion of zooxanthellae from coral tissues) • Ecological Limits • 18 - 32oC (low limit correlates with 20o N & S latitude limit of reef corals) • some exceptions exist • reasons for differences between lethal and actual limits • secondary effects of temperature on feeding or on reproduction • synergistic effects of other environmental factors (e.g., UV irradiance)

39. Global Distribution of Coral Reefs

40. Bleaching

41. Bleaching

42. Global Climate Change

43. Other Factors • Salinity • Sedimentation • Aerial Exposure at Low Tide • Water Motion • Inorganic Nutrients • Currents

44. Sediments

45. Nutrients and Algae Growth

46. 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