Effects of Artificial Reef Deployment on Nearby Resident Fishes

The effects of artificial reef deployment on fish communities residing in areas surrounding deployment sites were quantitatively measured. Two arrays of twelve small (2 × 1 × 0.5 m) artificial reefs made up of 2-in PVC pipe and concrete blocks were deployed in highly similar habitat in the Looe Key National Marine Sanctuary, Florida Keys, U.S.A. One array was designated as “control” while the other was designated “experimental.” Both arrays were allowed to recruit for over a full year. Fishes inhabiting sand plain habitats in two 6 hectare study sites in the vicinity of the two artificial reef arrays were censused prior to reef deployment, and then quarterly for over 1 year. Statistical comparison of these data resulted in no significant changes in species richness, total numbers of adult and juvenile fishes, or population densities of the five most abundant species. Fishes residing on all reefs were censused regularly. The number of fishes inhabiting the arrays stabilized in about 4–6 months. One year after deployment of these arrays, a comparatively large artificial reef made of 2-in PVC pipe and concrete blocks was deployed in the center of the “experimental” array. Fish aggregating devices (FADs) were positioned about 1–2 m above this reef to increase the effective surface area and structural complexity. Nine months after installation of this large central reef, the numbers of adult fishes [excluding Apogon spp.] residing on the experimental array had more than doubled, but remained essentially unchanged in the control array. These fishes were mainly snapper [Lutjanidae] and grunt [Haemulidae]. Our results demonstrate that, at least in some contexts, artificial reefs can result in a marked increase in the numbers of local resident reef fishes, without notable effects on fishes dwelling in nearby non-reef habitats.