Coral community decline at Bonaire, Southern Caribbean

We assessed the status of coral reef benthic communities at Bonaire, Netherlands Antilles, in December 2008 and January 2009 through ~5 km of photo transects taken at depths of 5, 10, and 20 m at 14 locations around the island. Univariate and multivariate analyses detected significant variation in benthic communities among depths and locations, as well as between leeward and windward sides of the island. Mean percentage cover of scleractinian corals ranged between 0.2% and 43.6% at the study sites and tended to be lowest at 5-m depth. The survey recorded 40 scleractinian coral species from 19 genera, within 10 families. Faviidae were by far the most abundant scleractinian family at all depths (predominantly Montastraea spp.), followed by Agariciidae at 20 and 10 m, and by Astrocoeniidae at 5-m depth. Macroalgal cover exceeded scleractinian coral cover at nearly all sites, averaging 34.9% (all samples pooled), compared with a pooled mean coral cover of 15.4%. Windward reefs were characterized by prolific growth of the brown algae Sargassum spp., and leeward reefs by growth of turf algae, Dictyota spp., Trichogloeopsis pedicellata (Howe) I. A. Abbott & Doty, and Lobophora variegata (Lamouroux) Womersley ex Oliveira. Damage from recent hurricanes was evident from the presence of toppled and fragmented corals, the movement of sand, and exposure of cemented Acropora cervicornis (Lamarck, 1816) rubble on the shallow reef platform. The combination of algal dominance and low to moderate coral cover are symptomatic of partly degraded reef systems, particularly as they coincide with elevated nutrients and reduced herbivory. 

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