Reef Fish Community Structure at Natural versus Artificial Reefs in the Northern Gulf of Mexico Estructura Reef Fish Comunidad en Natural contra Artificial Reefs en el Norte del Golfo de México Structure Reef Communauté Poisson au Naturel contre les Récifs Artificiels dans le Nord du Golfe du Mexique

Natural (n = 23) and artificial (n = 26) reefs were sampled in the northern Gulf of Mexico with a micro remotely operated vehicle (ROV) in 2009-10 to examine reef fish community structure. A total of 25,065 individuals was enumerated among ROV video samples; 91 fish taxa were identified, with 91% identified to species. Both habitat type and depth stratum (strata: 45 m) significantly affected reef fish community structure (PERMANOVA, p ≤ 0.002). Overall, greater diversity was observed among communities at natural reefs. Small demersal species, such as damselfishes, bigeyes, wrasses, butterflyfishes and Anthiinae basses, were among the more abundant species on natural reefs, yet were nearly absent from artificial reefs. Conversely, exploited species, such as red snapper and gray triggerfish, tended to have higher densities at artificial reef sites. These larger species may have been attracted to the higher profile of artificial (2 - 5 m) versus natural (typically < 2 m) reefs, or they simply may been more able to exploit those habitats due to less reliance on reef structure to avoid potential predators. Trophic ecology and growth rates should be compared between natural and artificial reefs to test for differences in the ecology of individual species. However, the community structure data alone are invaluable given they predate both the appearance of invasive red lionfish, Pterois volitans, and the occurrence of the Deepwater Horizon oil spill in this region.