Abstract

Artificial reefs have been used for purposes of habitat restoration, to provide structure in damaged areas or to enhance total reef area. Yet the ecological function that these reefs may fill is still not well defined. Of specific interest is how such reefs interact with adjacent habitats to affect overall fish community composition, and eventually production. During the first 10 months following deployment of small artificial reefs at Isla Ratones, Cabo Rojo, Puerto Rico, we compared fish diversity and community composition with fish on these reefs to those in the adjacent natural reef and sea grass beds. We conducted visual censuses by swimming transects over and around 10 artificial reefs, the shallow (<1.5m) and deep (>1.5m) natural reef and sea grass bed, of 15m2, 17m2 and 20m2, respectively. Species richness, evenness, density and mean size were compared. We observed 39 fish species in the artificial reefs, the most frequent being: Acanthurus chirurgus, Chaetodon capistratus, Lutjanus apodus, Ocyurus chrysurus and Stegastes leucostictus. Artificial reefs had a significantly greater number of species. Mean number of individuals/transect were significantly greater on artificial reefs, while natural reefs had higher densities than observed in sea grass. Size composition and abundance data indicate that artificial reefs were being used preferentially as nursery areas, relative to the natural reef, for 6 out of the 7 most abundant species found on the artificial reefs. Our results indicate that artificial reefs are being used principally as fish nursery habitat within the sea grass beds, providing the fish structure, rugosity, protection and food, and increasing the area where they can establish.

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