Impact/Purpose:

This research will develop assessment tools for coral reef ecosystems. Coral reefs are extremely sensitive to environmental changes and are considered sentinel ecosystems for global atmospheric and land use changes. Research will provide the sampling design, strategy, measurement endpoints, and integrative analysis to assess the condition of coral colonies and populations in different reef tracts and geographic areas. These tools can be further used, in combination with exposure measurements, to identify and characterize the interactive stresses that are adversely affecting corals. EPA collaborators and immediate users of data and tools include Region 4 (Florida Keys National Marine Sanctuary), the National Center forEnvironmental Assessment Global Change Program, and the Office of Water; all have needs to understand the changing condition of coral reefs and the potential causes. A broader user group includes managers of the Flower Gardens (Region 6) and Pacific (Region 10) coral reefs.

Description:

Complex reef structures formed by calcified coral skeletons provide a physical habitat that produces highly-valued ecosystem services, including shoreline protection and a high diversity and abundance of marine organisms that support lucrative fishing and tourism. Yet, coral reefs have experienced unprecedented levels of bleaching, diseaseand mortality during the last three decades. Several environmental conditions may be responsible for this dramatic decline. Among these are elevated water temperature, increased exposure to solar radiation, and degraded water quality. This research develops tools to assess condition of coral reefs and uses the information generated to draw associations with these and other potential stressors. Condition of corals is being characterized annually in a broad-scale survey that ranges across the reefs of southern Florida (41Km2) and includes sites in the Biscayne National Park, Florida Keys National Marine Sanctuary, and Dry Tortugas National Park. To date, surveys have monitored coral number and composition and prevalence of bleaching and disease. Results show that up to 28% of coral populations near Key West have been affected by disease or some, particularly reef-building Elkhorn corals, are not recovering. Elsewhere, disease prevalence was found to be considerably less; 79% of the Florida Keys reef tract was below 6% prevalence. Additional condition indicators are being developed and validated for inclusion in the survey. These include total coral surface area, percent living coral tissue, and living coral surface area. Combined with bleaching, disease and taxonomic endpoints, these additional endpoints will better characterize the value, health and sustainability of coral populations. Future research will explore the integration of these indicators into a condition index suitable for comparing different coral reefs and geographic areas over time. Performance of different management alternatives can also be examined using this tool. Although the condition indicators will provide useful insight to status and trend of coral publications, it is imperative for future management that declining condition is ultimately linked to a cause. Field assessments of the Florida reefs will be compared to exposure conditions, including sea water temperatures, solar light and ultraviolet-B irradiation, nutrients, contaminants, and turbidity. Any associations of poor coral condition will high exposure levels will be investigated in complementary laboratory studies to characterize stressor-response patterns for different species. Condition indicators and condition indices are necessary tools for assessing the effects of global climate and land use changes on coral populations, and for evaluating the performance of different management alternatives. Additionally, data generated by the field surveys will be used to determine which species, reefs and geographic areas are most valued, most at risk, and most responsive to potential management actions.

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