A comparative study of benthic and coral reef fish communities on artificial versus natural reefs of Bonaire, N.A.
Caribbean coral reef ecosystems are threatened by anthropogenic impacts such as pollution, overfishing, and habitat destruction. In an effort to alleviate these pressures and restore habitat, artificial reefs such as marina breakers, Reef Balls, and mooring blocks have been deployed and consequently colonized by marine species. Many studies have investigated the benthic and fish communities developing on these artificial structures as compared to adjacent natural structures. Results have shown that artificial reefs can successfully be colonized by benthic and pelagic communities but are not always comparable to the associated communities. The purpose of this study was to compare the composition of benthic habitat and the use of this habitat by fish between manmade mooring blocks functioning as artificial reefs and natural coral reefs of Bonaire. Quadrats were used to estimate and compare percent cover of benthic organisms on the top and west faces of mooring blocks versus the top and west faces of physically paired natural reef sites (n = 8). An 8 min visual census was conducted on each face of each site pairing to estimate fish abundance and diversity for those species interacting with the habitat. Results showed greater percent live benthic cover on the natural versus artificial reef. Benthic diversity was highest on the west face of the artificial reef when comparing the interaction of face and reef type, but did not differ significantly between reef types. Fish community diversity also did not differ between reef types. However, the composition of both benthic and reef fish community diversity differed greatly between the natural and artificial reefs. It was found that Montastrea annularis and sponges dominate the natural while the brain corals (Diploria labrinthiformis and Diploria strigosa) dominated the artificial reef. Bicolored damselfish (Stegastes partitus) and brown chromis (Chromis multilineata) were found in the highest densities on the natural reef, while sergeant major (Abudefduf saxatilis) and bluehead wrasse (Thalassoma bifasciatum) were found in the highest densities on the artificial reef. This study provides evidence that placement of artificial reefs does not cause a shift in overall benthic and reef fish community diversity on the natural reef, but may change the composition of this diversity.