Climate Change and Ocean Acidification
Florida Keys
Elevated water temperatures can cause corals to lose their zooxanthellae (a symbiotic microalgae) and bleach. Although corals may recover from brief episodes of bleaching, if ocean temperatures warm too much or remain high for an extended period, bleached corals will often die. Credit: FKNMS, NOAA
Why is it a concern?
Over the next century, climate change is projected to profoundly impact coastal and marine ecosystems. Climate change is having significant effects on sea temperature, sea level, storm intensity and currents. Increasing sea surface temperature has the potential to increase the frequency and intensity of both coral bleaching events and summertime tropical weather disturbances. Coral bleaching and hurricane damage have been identified as two of the main sources of mortality of two important reef-building corals in the Caribbean region: elkhorn coral and staghorn coral. These coral species have undergone such a drastic decline in abundance that the NOAA Fisheries Service listed these corals as ‘threatened’ species under the U.S. Endangered Species Act in 2005.
Elevated water temperatures cause corals and other reef organisms such as sponges and gorgonians to bleach, a process characterized by the loss of zooxanthellae (a symbiotic microalgae) from coral tissues. Although corals may recover from brief episodes of bleaching, if ocean temperatures warm too much or remain high for an extended period, bleached corals will often die.
Along with extreme temperature fluctuations from a changing climate, ocean acidification may also affect coral reefs in the Florida Keys as atmospheric carbon dioxide levels continue to increase. Since humans have contributed to greater amounts of CO2 into the atmosphere over the past century, the ocean has absorbed CO2 at an increasingly rapid rate, changing the ocean’s chemistry and leading to ocean acidification. Due to the increased acidity of seawater, many of the animals and plants in the ocean that have calcium carbonate skeletons or shells, such as corals, may experience reduced growth or ability to generate hard shells. Ocean acidification could prompt a chain reaction of impacts through the marine food web, beginning with larval fish, shellfish, and corals, cutting valuable ecosystem services provided by coral reefs such as food security, tourism, shoreline protection, and biodiversity.
Overview of Research
Research conducted by Sanctuary scientists and partners provides critical information to address existing and emerging resource conservation and management issues. The Overview of Research highlights some, but not necessarily all, of the research activities completed or ongoing at the Sanctuary.
Science Needs and Questions
The best available science is used by Sanctuary scientists and managers working to address priority resource conservation and management issues. As priorities change and new issues emerge, each Sanctuary develops new science needs and questions and works with partners to address them.
- What characteristics of a specific geographic area confer resistance or resilience to bleaching, disease, and effects of climate change?
- What characteristics of each coral species confer resistance or resilience to bleaching, disease, and effects of climate change?
- How far in advance can bleaching events be predicted using currently available tools?
- What is the predictability of bleaching and disease events in terms of duration and geographic scope?
- How do bleaching and disease conditions affect other components of the ecosystem (e.g., fish, reef invertebrates, sponge pumping rates, etc.)?
- How do increased concentrations of carbon dioxide (i.e., ocean acidification) affect reef accretion, coral larvae formation, metamorphosis, growth and survival, resistance or resilience to disease, bleaching, and other stressors?
- How do increased concentrations of carbon dioxide (i.e., ocean acidification) affect physiologic development in fish? Does this in turn affect their foraging or defensive behaviors?
- How do increased concentrations of carbon dioxide (i.e., ocean acidification) affect sponge spicule development? Invertebrate exoskeletal development?
Education and Outreach Material
Florida Keys NMS Web site, coral bleaching & ocean acidification
Office of National Marine Sanctuaries Climate Change Website
Waterways episode re: climate change
Bleach Watch
References
Gittings, S.R., M. Tartt, and K. Broughton. 2013. National Marine Sanctuary System Condition Report 2013. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, Office of National Marine Sanctuaries, Silver Spring, MD. 33 pp.
IPCC (Intergovernmental Panel on Climate Change). 2001. Climate Change 2001: Synthesis Report. A Contribution of Working Groups I, II, and III to the Third Assessment Report of the Intergovernmental Panel on Climate Change [Watson, R.T. and the Core Writing Team (eds.)].
Cambridge University Press, Cambridge, United Kingdom, and New York, NY, USA, 398pp.
Lesser, M.P. and S. Lewis. 1996 Action spectrum for the effects of UV radiation on photosynthesis in the hermatypic coral Pocillopora damicornis. Mar Ecol Prog Ser 134:171-177.
Ocean Acidification Reference User Group. 2009. Ocean Acidification: The Facts. A special introductory guide for policy advisers and decision makers. D. d'A. Laffoley, and J.M. Baxter (eds). European Project on Ocean Acidification (EPOCA). 12pp.
ONMS (Office of National Marine Sanctuaries). 2011. Florida Keys National Marine Sanctuary Condition Report 2011. U.S. Department of Commerce, National Oceanic and Atmospheric Administration, Office of National Marine Sanctuaries, Silver Spring, MD. 105 pp.