Sea Level Rise and Coral Reefs: Predicting Responses. Pamela Hallock College of Marine Science University of South Florida St. Petersburg, FL 33701

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1 Sea Level Rise and Coral Reefs: Predicting Responses Pamela Hallock College of Marine Science University of South Florida St. Petersburg, FL 33701

2 Acknowledgments Funded by EPA's Science To Achieve Results (STAR) Program Grant # R Views expressed are those of the speaker and do not imply endorsement of these views by USF or agencies that funded aspects of this research

3 CORAL REEFS ARE THREATENED WORLDWIDE

4 STATUS OF CORAL REEFS OF THE WORLD: % already lost 15% severely threatened 20% under longerterm threats 46% relatively healthy

5 Declining coral cover Nuisance algal blooms Implications of Reef Decline Increased bioerosion Loss of reef structure

6 Implications of Reef Decline Loss of habitat

7 Societal & Economic Implications of Reef Decline Loss of fisheries Loss of biodiversity Loss of natural product resources Changes in sediment production & quality Coastal erosion Loss of tourism

8 SCALE OF THREATS Local impacts Grounding, recreation, construction, spills Local impacts on a global scale Coastal pollution, sediments, overfishing Regional impacts New diseases, invasive spp., rivers, dust Global change Increasing CO 2, ozone depletion

9 LOCAL IMPACTS

10 LOCAL IMPACTS GLOBAL EXTENT

11 MULTIPLE STRESSES Natural stresses Example: hurricanes Natural stresses amplified by human activities Example: storm runoff from agricultural areas New anthropogenic stresses Example: pesticides in storm runoff

12 IMPACTS REGIONAL

13 WHITE-BAND DISEASE DIADEMA DIEOFF

14 GLOBAL THREATS TO CORAL REEFS Alteration of global nutrient cycles Ozone depletion/increasing photic stress Increasing CO 2 Increasing frequency and intensity of storms Global warming Ocean acidification Sea level rise

15 BASIC PROBLEM NASA Evidence: global environmental degradation Human populations have exceeded the long-term carrying capacity of the planet (Erlich et al. 1995)

16 Humans have doubled nitrogen fixation in terrestrial environments Consequences: Community phase shifts Increase in HABs Expanding hypoxic zones

17 Stratospheric Ozone Depletion Destruction of Earth s protective stratospheric ozone layer Naturally by chemicals produced by volcanic eruptions Since the 1950s by man-made ozone-depleting chemicals Major volcanic eruptions greatly increase the destructive effects of man-made chemicals Consequences - more biologically damaging ultraviolet radiation (UVB) reaching Earth s surface Higher rates of skin cancer and cataracts in mammals Enhanced toxicity of pesticides and herbicides Higher rates of breakdown of tannins (sunscreens) in natural waters Higher probability of photo-oxidative stresses E.g., bleaching in coral reefs

18 Bleaching Loss of color in animals that host algal symbionts Chlorophyll in the algae may be damaged or Host may expel their algae Major cause: photo-oxidative stress Too much solar radiation (light and UV) or Rise in temperature that results in the inability to tolerate high light Consequences If they recover, reduced growth and reproduction If extreme, death

19 CORAL BLEACHING

20 Ozone anomaly Bleaching and Ozone Anomalies 4 3 Mass coral bleachings El Chichon Nevada del Ruiz Mt. Pinatubo Year Modified from Roscoe 2001

21 GLOBAL THREATS TO CORAL REEFS Alteration of global nutrient cycles Ozone depletion/increasing photic stress Increasing concentrations of atmospheric CO 2 Increase in weather extremes Ocean acidification Global warming Temperature stress Sea level rise

22 MORE FREQUENT SEVERE STORMS

23 INCREASING CO 2 : As ocean waters become more acidic, more energy is needed to build shells and skeletons

24 Intergovernmental Panel on Climate Change 2001 WHAT IS HAPPENING AS ATMOSPHERIC CO 2 INCREASES? Eocene levels Double Pre-industrial

25 KLEYPAS et al. (1999) (research team at National Center for Atmospheric Research) Atmospheric CO 2 will be double preindustrial levels by 2065 Ocean saturation for aragonite will decrease by 30% Production of aragonite shells will likely decrease by 14-30% Models predict below critical saturation nearly globally by 2100

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27 Aragonite saturation at pco 2 = 280 ppm (pre-industrial) Zone of coral tolerance >3.5 <3.5 Livebottom Reefs

28 Aragonite saturation at pco 2 = 560 ppm (double pre-industrial) PREDICTIONS FOR THE 21 ST CENTURY: OCEAN CHEMISTRY Zone of coral tolerance >3.5 Reefs Livebottom <3.5

29 Global Warming Climate models predict annual bleaching already in some regions and within a few decades in other regions

30 SEA SURFACE TEMPERATURE o C TAHITI BLEACHING TEMPERATURE PHUKET JAMAICA YEAR (Hoegh-Guldberg 1999)

31 IMPLICATIONS OF BLEACHING

32 Sea level rise: what is the threat to coral reefs? How do coral reefs respond to sea level rise? What are the predictions for SL rise this century? Consequences for human populations on low-lying islands?

33 How do coral reefs respond to sea level rise? (Hubbard 1997

34 Light & Reefs General rule Branching corals >~60% of seasurface light (SSL) Head corals >~20% of SSL Plate corals >~4% of SSL Hallock (2005)

35 Sea level rise as indicated by Acropora palmata (Hubbard in press)

36 Sea level rise since last glacial maximum ~100 m in 10K yrs ~1 mm/yr

37 Blanchon and Shaw (1995) Catastrophic Rise Events: up to 4.5 cm/yr for several hundred years Backstepping

38 Keep-up reefs last 7000 years (Hubbard 1997 Buck Island Reef, USVI, accreted and prograded as sea-level rise averaged ~0.2 cm/yr

39 Centimeters Rates of bioerosion, accretion and SL rise Rise: +1 cm/yr CRE: +4.5 cm/yr Accretion/rise: +0.5 cm/yr Accretion/rise: +0.2 cm/yr Accretion or rise: +0.1 cm/yr Bioerosion: -1 cm/yr Years

40 Key Largo Key West Coral reefs or low-lying human communities: which will be impacted first? Belize City Majuro Atoll

41 With sea level rise, entire atollbased countries face extinction Maldives: attempting to build upward Tuvalu: treaty with New Zealand to take their population Marshall Islands????? Former American Trust Territory Will the US absorb the Marshallese? Whole cultures will be lost!

42 CORAL REEFS ARE THREATENED WORLDWIDE BY HUMAN ACTIVITES But on human time scales, sea level rise is primarily a geopolitical and humanitarian concern

43 WE MAY BE THE LAST HUMAN GENERATIONS TO SEE SHALLOW- WATER CORAL REEFS! BUT NOT BECAUSE OF SEA LEVEL RISE!

44 LIVEBOTTOM COMMUNITIES SHOULD PERSIST WHERE WATER QUALITY IS SUITABLE Thank you