ANALYSIS OF CORAL REEF DECLINE IN BONAIRE

Photo transects of reefs were taken from May to June 2006 at 36/89 dive sites in Bonaire National Marine Park to evaluate reef health from 10 and 20 meter depths and to assess temporal variation of corals. Seafloor cover identifications were based on AGRRA protocol and percent cover was estimated using Coral Point Count with Excel extensions. Results indicate mean coral cover was 20.4 ± 0.6% inclusive of 44 scleractinian coral species from 20 genera and 10 families. Other important indicators were diseased coral 0.06 ± 0.01% , recent dead coral 5.4 ± 0.3%, old dead coral 29.1 ± 0.6%, and macroalgae 1.9% ± 0.2%. Coral community composition was indicative of reef degradation with dominance of only one genus (Montastraea), the presence of mostly stress tolerant massive and submassive corals, and reef flattening. At one study site temperature data gathered from an independent source from May 2004 to June 2005 reveals average nighttime temperatures of 27.71 °C at 12m and 27.66 °C at 20 m depth. Long term changes in Bonaire reefs were evaluated by comparisons of 2006 data to published works. Comparisons indicate a decrease in live coral and macroalgae cover through time at sites available for comparison. Data show that coral cover decreased more rapidly in Bonaire (0.65%) than for the Caribbean (0.29%) from 1982-2006. Declines were especially high after 2006 with more than 2% coral loss per year. Macroalgae data were gathered from 1999 to 2009, however, the number of sites with data available for study varied through time. During most of the time surveyed, macroalgae cover was low and average macroalgae cover was 15% in 1999, 2.8% in 2003, 2.9% in 2005, 3% in 2006, 14.4% in 2007, 27.6% in Jan. 2008, 23.4% in Dec 2008, and 3.6% in 2009. Spikes in macroalgae cover appear to be associated with hurricanes including Lenny in November 1999 and Felix in September, 2007. Although historically Bonaire reefs had higher coral and lower macroalgae cover than other reefs in the Caribbean, the high abundance of recent dead coral cover in 2006 suggested that Bonaire reefs may be degrading more rapidly than others in the Caribbean region.