DOI: 10.5281/zenodo.10882238
title: Ten years (2013-2023) of fish assemblage data collected seasonally with underwater visual surveys on paired artificial and natural reefs

description: The study of assembly patterns and dynamics of organisms has long remained a foundational theme in ecology. Further, the relationship between assemblages and different habitats can provide important insight on ecological processes and guide management and conservation efforts (e.g., restoration, protected areas). We conducted underwater visual surveys of reef fish assemblages at 14 sites in the eastern Gulf of Mexico, including eight that were paired artificial and natural reefs. By using a paired design, we controlled biotic (e.g., larval supply), abiotic (e.g., depth), and socio variables (e.g., fishing access) to isolate the effect of reef type. Trained scientific SCUBA divers with extensive experience with reef fishes from the broader tropical western Atlantic region conducted two to four 10-minute stationary surveys on the paired reefs each season (i.e., calendar quarters) for 10 years from spring 2013 to spring 2023. We also surveyed six additional artificial reefs from winter 2020 to spring 2023 that lacked natural reef pairs. During each survey, the divers identified and estimated the total lengths of all taxa observed within an imaginary cylinder around them. The imaginary cylinders had a radius up to 7.5 meters (depending on horizontal visibility) and extended from the seafloor to the highest visible water above the diver. During the period of study, we conducted a total of 1,350 surveys and counted 544,736 fish that represented 171 taxa (most at the species level). Analyses of these data have revealed habitat-specific heterogeneity of the fish assemblages at both taxonomic and functional trait levels, the importance of herbivory in structuring the benthos, and socio-ecological interactions in the system, among other findings. These data may be useful for other researchers interested in patterns and dynamics of populations and communities, functional traits, taxa-habitat relationships, and for parameterizing statistical, joint distribution, metacommunity, and ecosystem models. In addition, because many of the observed taxa are of management concern, they may be useful for researchers interested in fisheries science. The data are free to use, are not copyright restricted, and we ask users to cite this data paper.
description: We non-destructively quantified the abundances and sizes of fishes using the underwater visual census technique developed by Bohnsack and Bannerot (1986). This standardized method has been used extensively (the publication has been cited 796 times via Google Scholar as of April 15, 2024) in reef environments globally (e.g., Harrison et al. 2021, Knoester et al. 2023, Micheli et al. 2005, Ruttenberg et al. 2019). Upon arrival at a study site, two trained scientific SCUBA divers (see Class II.B.4) descended to the seafloor. Each diver conducted one to two 10-minute surveys. During each survey, the divers separated from each other far enough to avoid overlap in the reef and water column that they observed. Each diver hovered ~1 meter off the seafloor, and slowly rotated to observe all fishes within an imaginary cylinder with a radius up to 7.5 meters (depending on horizontal visibility) from the seafloor to as high in the water column that was visible. This distance was determined by Bohnsack and Bannerot (1986) because it maximized the number of fish that could be counted during the 10-minute survey and allowed for the inclusion of fishes ranging from small cryptic species to larger, more diver-phobic ones. During each survey, we identified all fishes observed within the cylinder (usually to species) and estimated their total lengths in centimeters. For schooling and shoaling species, we estimated the mean, minimum, and maximum lengths in centimeters.