Artificial structures are the dominant complex marine habitat type along the northwestern Gulf of Mexico (GOM) shelf. These habitats can consist of a variety of materials, but in this region are primarily comprised of active and reefed oil and gas platforms. Despite being established for several decades, the fish communities inhabiting these structures remain poorly investigated. Between 2012 and 2013 we assessed fish communities at 15 sites using remotely operated vehicles (ROVs). Fish assemblages were quantified from standing platforms and an array of artificial reef types (Liberty Ships and partially removed or toppled platforms) distributed over the Texas continental shelf. The depth gradient covered by the surveys (30–84 m) and variability in structure density and relief also permitted analyses of the effects of these characteristics on fish richness, diversity, and assemblage composition. ROVs captured a variety of species inhabiting these reefs from large transient piscivores to small herbivorous reef fishes. While structure type and relief were shown to influence species richness and community structure, major trends in species composition were largely explained by the bottom depth where these structures occurred. We observed a shift in fish communities and relatively high diversity at approximately 60 m bottom depth, confirming trends observed in previous studies of standing platforms. This depth was also correlated with some of the largest Red Snapper captured on supplementary vertical longline surveys. Our work indicates that managers of artificial reefing programs (e.g., Rigs-to-Reefs) in the GOM should carefully consider the ambient environmental conditions when designing reef sites. For the Texas continental shelf, reefing materials at a 50–60 m bottom depth can serve a dual purpose of enhancing diving experiences and providing the best potential habitat for relatively large Red Snapper.

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Vibrio spp. are ubiquitous members of aquatic microbial food webs that can be pathogenic to humans and a range of other organisms. Previously published predictive models for Vibrio spp. concentrations in estuarine and coastal waters, based only on salinity and temperature, are 70 to 75% accurate during 'normal' conditions (e.g. not during storms or drought). We have conducted a preliminary comparison of the output from this type of model to the natural concentrations of both total Vibrio spp. and the potentially pathogenic Vibrio vulnificus when measured during tropical storms. Water samples were collected in situ from a deployed platform in the Neuse River Estuary (NRE), North Carolina, USA, during 2 storm events: Hurricane Ophelia and Tropical Storm Ernesto. Total Vibrio spp. concentrations were measured using culture-based methods and V. vulnificus levels were determined using a newly developed, rapid quantitative polymerase chain reaction (QPCR) assay. Results were analyzed in relation to environmental parameters and to concentrations of the fecal indicator bacteria Escherichia coli (EC) and Enterococcus spp. (ENT). Total concentrations of Vibrio spp. in the NRE were often orders of magnitude higher than those predicted by a previously published model. These large deviations from model predictions may indicate contributions from storm forcing (e.g. resuspension, surges) that are missing from the calm weather observations used to build these models.

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Oil and gas platforms along the northwestern Gulf of Mexico (GOM) shelf have served as artificial reefs since oil and gas exploration intensified in the 1950s. As these structures are decommissioned, they must be removed; however, some are converted to permanent artificial reefs. Despite the potential effects these artificial habitats may have on marine fisheries, investigations that assess the fish communities inhabiting these structures relative to natural habitats are rare. During fall 2012, we used remotely operated vehicle surveys to compare fish communities between artificial reefs (i.e., reefed platforms; n = 5) and adjacent natural banks (n = 5) in the western GOM. Our surveys successfully documented 79 species representing 28 families. Multivariate analyses suggested that fish communities at artificial reefs were distinct from those at natural banks. Post hoc analyses indicated that the differences were driven by high abundances of transient, midwater pelagics and other gregarious species at artificial reefs. Many fisheries species, like the Red Snapper Lutjanus campechanus, were found in both habitat types, with density at artificial reefs estimated to be nearly eight times greater than at natural banks. Despite lower densities at natural banks, the disproportionately large areas of these habitats resulted in relatively high total abundance estimates-approximately 5% of the 2012 GOM Red Snapper annual catch limit (3.67 million kg [8.08 million lb])-a finding that has significant implications for Red Snapper and artificial reef management in the GOM. Our study suggests that although fish community structure may differ between these two habitats, artificial reefs serve as important habitat for species like Red Snapper by potentially diverting fishing pressure from natural habitats; however, future studies that address speciesspecific life history traits will be needed to better understand the function and performance of artificial reefs in supporting fisheries productivity.