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CORAL REEF RESPONSES TO GLOBAL CLIMATE CHANGE
Citation:
Fisher, W S. CORAL REEF RESPONSES TO GLOBAL CLIMATE CHANGE. Presented at U.S. EPA Science Forum 2002: Meeting the Challenges, Wash., D. C, May 1-2, 2002.
Description:
Increased emissions of greenhouse gases and synthetic compounds are related to rising sea temperatures and increased penetration of ultraviolet radiation (UVR), two factors that are consistently linked to bleaching and disease of corals. Coral reefs play a major role in the environment and economies of Florida, Hawaii and most U.S. territories in the Caribbean and Pacific Ocean. Coral reefs are valuable economic resources for fisheries, recreation, tourism, and coastal protection from storms. They are also one of the largest global storehouses of biodiversity, with hundreds of thousands of dependent species that are the substance of a
flourishing and extensive marine ecosystem and a potential wealth of natural products.
Geological records show that coral community structure has been stable over the last 220,000 years, despite coral sensitivity to small changes in physical and chemical parameters. Yet, during the last three decades of warming sea temperatures, coral bleaching and disease have escalated worldwide, placing coral reefs and their valuable resources at risk. Laboratory studies have validated that high temperature or elevated UVR can cause bleaching in several species. Many corals do not recover and are overgrown with macroalgae while others can become more susceptible to disease. The current deterioration of coral reefs is unprecedented and will likely have profound implications for U.S. economies and marine ecosystems.
The EPA/National Health and Environmental Effects Research Laboratory (NHEERL) Global Change Research Program is focused on assessing the effects of global change on coastal aquatic ecosystems, including coral reefs. In collaboration with EPA's Office of Water, methods to assess coral disease and bleaching have been developed and validated, and disease frequency and distribution have been surveyed in the Lower Florida Keys. Parallel surveys in the Upper and Middle Keys were coordinated with EPA Region IV. Laboratory culture
systems are employed for controlled dose-response investigations. A variety of coral species and several clones of the symbiotic algae Symbiodinium sp. are maintained for testing. Exposures to temperature and light variables are accomplished with a solar simulator system, which controls both UVR and photosynthetically-active light. These laboratory methods and tools have been particularly useful in collaborative research with EPA's National Exposure Research Laboratory and the University of California to characterize the effects of UVR on thymine dimer formation, an indicator of stress, in multiple species of coral. Both field and laboratory studies such as this are required to conclusively link deterioration of our natural
resources to their cause(s) so that precise actions can be prescribed to mitigate future losses.