SPATIAL AND TEMPORAL VARIATION IN BONAIRE SCLERACTINIAN CORAL COMMUNITIES

Coral reefs in Bonaire National Marine Park (BNMP) have had a long history of marine protection and were designated the most pristine in the Caribbean Region by NOAA in 2008. BNMP protects 2,700 hectares of marine ecosystems from the shoreline to a depth of 60 meters. We analyzed photo transects taken in 2006 from 10 and 20 meter depths at 36 dive sites around BNMP, with the majority from the leeward side of the island. Our analysis represents approximately 1/3 of all dive sites available for study. A total of 717 photos were examined using Coral Point Count with Excel extensions to estimate the percent seafloor cover from each 90 by 90 cm photo. Identifications were based on AGRRA protocol. Sample size, in terms of total number of points overlain on photos, was much larger in this study than previous work in Bonaire with a total of 142,037 points. Results of the combined 10 and 20 meter analyses indicated average cover of live coral was 20.4%, recently dead coral 5.3%, diseased coral 0.1%, macroalgae 1.9%, other algae 11.8%, sponges 3.0%, gorgonians 5.4%, Millepora sp 0.7%, old dead coral 22.2%, and substrate 28.6%. Dominant families were Faviidae (12.8%), Agariciidae (3.3%), Astrocoeniidae (1.6%), and Poritidae (1.3%). A total of 44 species were identified but most had less than 1% percent cover. Foremost was the Montastraea annularis species complex (10.1%), with M. faveolata (6.9%) dominating the complex, but Agaricia agaricites (2.4%), Montastraea cavernosa (1.3 %), Porites astreoides (1.1%) and Stephanocoenia intercepta (1.1%) were also represented. Significant small-scale variation in the coral communities was detected between depths and among sites. Site macroalgae ranged from 0 to 19%, coral cover from 1.9 to 38.8% and coral species richness from 4 to 24 species. When analyzing biota separately by depth, coral cover was significantly lower at 10 meters (17.8%) than at 20 meters (23.1%) with a p = 0.000. Montastraea faveolata and Montastraea annularis were the most common species at 10 meters whereas Montastraea faveolata and Agaricia agaricites were most common at 20 meters. Comparisons to past studies indicated a decrease in live coral cover through time for several decades before this study. However, a short-term increase in average coral cover occurred from 2006 (19.9%) to 2008 (23.1%) at sites available for comparison.