SGER: Local Extinction of Acropora Cervicornis, the Primary Framework Builder of Lagoonal Reefs in Belize

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Aronson9901969 Over the past two decades, coral reefs around the world have changed dramatically. Coral cover has declined, and in many cases fleshy macroalgae have increased. This change has been particularly pronounced in the Caribbean region. Hurricanes, coral bleaching, diseases, overfishing, eutrophication, pollution, sedimentation, and other factors may all be involved, but their relative importance is poorly understood in most situations. Global climate change may interact with and exacerbate the effects of these disturbances and stresses. Some have suggested that the coral-dominated and macroalgal-dominated situations represent alternative community states, each of which is resistant to conversion to the other. The recent switch to macroalgal dominance, caused by what appears to be a unique conjunction of natural and anthropogenic disturbances, may be unprecedented in the Pleistocene-Holocene history of the Caribbean. With the widespread occurrence of bleaching in coral reefs, including Belize, there have been dramatic changes in the dominant members of coral reefs systems. In the Belizean inner lagoon, the large framework building Acroporids have been losing out to other forms. Now with the disturbances of Hurricane Mitch, there is a possibility that virtual extinction of these once dominant (recent and past) forms may achieve local extinction. This Small Grant for Exploratory Research will help to start addressing the following questions. Did Hurricane Mitch, rapidly following the coral bleaching episodes, cause the extinction of Acropora cervicornis in the central lagoon? Did Agaricia tenuifolia also suffer heavy mortality? Will Echinometra viridis be able to control algal populations in the face of massive provision of substratum (dead coral skeletons)? Will space opened by Hurricane Mitch actually promote the recovery of A. cervicornis populations (contrary to expectation), bringing them back from the edge of extinction? This rapid response funding will enable Dr. Aronson to address several issues of current concern, including modem-day extinctions and the contribution of different forms of disturbance to unique changes on coral reefs. The first order of business is clearly to assess Hurricane Mitch's effects as soon as possible. Then the data collected over the next several months will be published rapidly, and will be used as a basis for future research