IS CORAL GARDENS, BELIZE A REFUGIUM FOR THE CORAL ACROPORA CERVICORNIS?

A number of anthropogenic and natural disturbances have proven detrimental to coral reef health worldwide in recent decades. A phase shift from coral- to macroalgae-dominant reefs is pervasive and has been well documented in the Caribbean. Acropora cervicornis (staghorn coral) has been particularly affected by this shift due to mass mortality of this species since the 1980s. In recent years few Caribbean A. cervicornis refugia have been documented. This study characterizes the health of Coral Gardens, a 10,180 m² patch reef off the coast of Belize, where this stony, branching coral is the dominant species and appears to be thriving. Relative abundance of live A. cervicornis was assessed from photographic data collected along five semi-permanent transects across the reef. During the summers of 2011, 2012, and 2013, 62, 131, and 132 meter square quadrats were photographed, respectively, with the goal of capturing virtually the same surface area during all three visits to the site. Photographs were digitized and manually segmented using Adobe Illustrator, and percent live coral cover was calculated using MATLAB. Aggregate data from the total population of 264 quadrats from both 2012 and 2013, showed a net growth in A. cervicornis from 30.7% to 31.2% live coral per m². Thirty eight pairs of quadrats showed distinctive features (i.e. rubble, soft coral, unique coral branch shape) in both 2012 and 2013, and 5 quadrats overlapped in 2011, 2012, and 2013. Of the 38 overlapping quadrats, half showed greater A. cervicornis abundance in 2013, with an average difference per pair of -0.96% live cover from 2012 to 2013. Of the 5 quadrats with 3-year overlap, 3 showed an increase in abundance from 2011 to 2012. These data suggest that live A. cervicornis cover at Coral Gardens is variable across transects and years, but does not appear to be suffering the decline documented on many other Caribbean reefs in previous years. If the A. cervicornis population at Coral Gardens remains stable, the site could be classified as a refugium for this endangered coral species. Such a conclusion may be helpful in earning protected status, allowing the reef to remain a healthy refuge and possible facilitator of A. cervicornis resurgence.