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Climate Change and Land Use Patterns: Impact on Coral Reef Dynamics in Puerto Rico

This study examines the effects of climate change and contrasting land use patterns on the historical dynamics of reef-building corals in Puerto Rico. The research highlights increased ecosystem vulnerability and the potential for ecological collapse. The study provides preliminary findings and outlines future steps to address these issues.

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Climate Change and Land Use Patterns: Impact on Coral Reef Dynamics in Puerto Rico

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  1. Effect of climate change and contrasting land use patterns on historical dynamics of reef-building corals in Puerto Rico: A story about increased ecosystem vulnerability and ecological collapse Edwin A. Hernández-Delgado Raisa Hernández-Pacheco, Tagrid Ruiz-Maldonado University of Puerto Rico, Department of Biology, Center for Applied Tropical Ecology & Conservation Coral Reef Research Group, UPR-RP coral_giac@yahoo.com NSF External Scientific Advisory Committee Symposium Center for Applied Tropical Ecology and Conservation UPR-RP, November 12-14, 2009, San Juan, PR

  2. Objectives • Brief overview of current coral reef crisis. • Project’s research questions and goals. • Preliminary findings. • Additional current and future steps. Coral Reef RIP Mrs. Globalization Mrs. Reductionist Science http://www.cartoonstock.com/directory/d/dying.asp

  3. Facts • Sea surface temperatures and CO2 concentrations have reached unprecedented high levels during the present decade. • Current sea surface warming and ocean acidification trends (as a result of increased CO2 concentrations) have driven coral reef ecosystems into an unprecedented state of vulnerability. • Reef deterioration often occurs in response to multiple stressors acting simultaneously or synergistically.

  4. Facts • A single sea surface warming event in 2005 caused an unprecedented coral mortality event in the Caribbean at least within the last 220,000 years (Pandolfi & Jackson, 2006). • A degraded environment has a strong influence on coral reef resilience. Declining environment increase reef vulnerability to sea surface warming (=bleaching) and reduce its resilience. • Time scales necessary for coral reef recovery from any type of disturbance will increase with increasing spatial scales of impacts.

  5. Facts • Coral reefs are going into a state of ecological collapse if conditions necessary for recovery are inadequate. • Coral reefs vulnerability to environmental changes, including disrupted carbon cycle pathways (acidification), may lead to potential mass extinction events in the near future.

  6. Facts • Under the current very rapid rates of climate change (100-1,000 times that of the most rapid environmental changes over the past 420,000 years at least), coral slow rates of evolutionary change are unlikely to keep pace. • The time scale of most current impacts (months to decades) is so fast that corals evolutionary adaptation (millennia at least) is not even an option.

  7. Facts • Puerto Rico is undergoing continuously increasing pressures of development, with simultaneously rapid declining environmental and socio-economic conditions. These have resulted in net long-term coral reef declines. • Current spatial magnitude of coral mortality will require radical actions and decisions, both in land and sea. • Under current pace of decline large-reef building corals will require a recovery time scale out of our context.

  8. Research questions • Historical trends • Which have been the recent historical trends in proxy signals recorded in reef-building coral annual growth bands to climate change dynamics as well as changes in land-use patterns in the dry karstic zone in PR? • Current and future trends • What are the effects of climate change and localized anthropogenic factors on coral reef ecosystem dynamics?

  9. “Montastraea annularis” • Species complex: • M. annularis. • M. faveolata. • M. franksi. • Wide bathymetric distribution (>60 m), principal reef-builder in the Atlantic. • Simultaneous hermaphrodites. • Annual reproductive cycles. • Extremely low sexual recruitment rates. • High recruit mortality rates. M. faveolata

  10. “Montastraea annularis” • Annual skeletal growth rate <1 cm. • Highly susceptible to different diseases and/or syndromes. • Inability to recover lost tissue following disease/syndrome impacts. • Susceptible to prolonged exposure (>8-15 DHWs) to SSTs 1-2°C above MMM. • Susceptible to chronic water quality degradation (i.e., transparency, sedimentation, eutrophication). Bleached M. faveolata

  11. “Montastraea annularis” • Susceptible to a wide diversity of competitors (i.e., sponges, encrusting tunicates, algae, cyanobacteria). • Deepwater (>30 m) colonies appear to be in better shape than those from shallower reefs. • All surveyed shallow-water reefs (<20 m) show at least a moderate degree of population declines. M. annularis

  12. Declining M. annularis abundance withincreasing water turbidity Threshold in transparency?

  13. Significant coral reef decline within 1997-2009 -81% -69%

  14. Collapsing population of Montastraea annularis -72% -52%

  15. Other examples from PR

  16. Eastern PR coast: M. annularis species complex population collapse?

  17. Year-round thermal anomalies (2003-2008)

  18. Mass bleaching impacted M. annularis complex • Montastraea spp. impacts: • M.annularis 97.1% • M. faveolata 90.4% • M. franksi 92.1% • M. cavernosa 36.7% Hernández-Delgado et al., unpub. data

  19. Community structure and oceanographic patterns influenced bleaching severity Severe Limited circulation Moderate Minimum Moderate circulation Strong Circulation

  20. Mona Island’s coral reefs are also collapsing

  21. Abrupt decline in % living tissue cover

  22. Major reef-building species undergoingsignificant mortality • Most large reef builders have recently died or have suffered significant partial mortality. • High prevalence of YBD and other syndromes.

  23. Dramatic post-bleaching loss in % living tissue cover followed by physiological fragmentation (2005-2009)

  24. Significant mortality in smaller size categories Preliminary modeling of population survival and growth suggest that recovery is unlikely and that they might be prone to extinction under recurrent sea surface warming and bleaching as most climate models predict.

  25. Long-term consequences of climate change and other human insults in coral reef functional roles Colony physiology, Holosimbionts, Microbes Declining food Production!

  26. Further steps • Develop studies regarding bioerosion rates under different environmental conditions. • Document coral recruitment rates.

  27. The past is still the key to the present! • Joint efforts between CATEC, CCRI, and IRS to develop large scale sclerochronological studies to: • Address historical rates of ecological change across large spatial scales. • Determine historical patterns of change in coral reefs across anthropogenic gradients (Guanica, Mona, SW PR shelf, NE PR shelf). • Discriminate between historical trends of localized human impacts and climate change.

  28. Apply sclerochronological tools to address impacts of climate change on physiological fragments • Address impacts of colony physiological fragmentation on: • Skeletal extension rates. • Skeletal density. • Calcification rates. • Test impacts on different fragment size categories. • Test hypothesis regarding before-after coral ability (or inability) to recover from recurrent mass bleaching events (1987, 1998, 2005).

  29. A final thought • “The outlook for reefs in the face of today’s rapid global warming is exceptionally serious” (Veron, 2008). • “The imminent demise of reefs is perhaps the strongest signal yet that the planet is on the brink of an environmentally-led mass extinction” (Veron et al., 2009). • Whether or not this is so, “reefs are likely to be the first major planetary-scale ecosystem to collapse in the face of climate changes now in progress” (Sheppard et al., 2009).

  30. A final thought • There is still a paramount need to: • Reduce harvests of herbivorous fish to sustainable levels. • Protect and restore top predators to maintain effective food webs. • Restore water quality (by also protecting watersheds, managing land use, reducing non-point source pollution and improving sewage treatment efficiency).

  31. A final thought • There is still a paramount need to: • Reduce other sources of anthropogenic stressors (to reduce cumulative and/or synergistic impacts). • Establish additional networks of marine protected areas (to protect and enhance connectivity). • Coral farming and reef rehabilitation (to restore coral ecological functions, foster coral sexual reproduction and improve resilience). • Reduce greenhouse gas emissions (to prevent further screwing up Mother Earth)!!!

  32. Acknowledgements • This presentation was made possible by: • NSF through UPR-CREST-CATEC • NOAA/CSCOR (NA04NOS4260206, NA05NOS4261159, NA07NOS4000192 through CCRI/UPR). • NOAA/CRCP (NA05NMF4631050 to UPR/CRRG). coral_giac@yahoo.com http://ccri.uprm.edu/ http://crest-catec.hpcf.upr.edu/ 787-764-0000, x-2009

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