Variation in habitat preferences among coral reef fishes is explained by benthic composition

Dixson, Danielle L.Coral reefs are declining dramatically, causing a shift in benthic community composition and a loss of structural complexity. Changes to the benthic community can result in a loss of diversity, ecosystem function, and resilience. A shift in the benthic composition can have a strong influence on fish abundance and diversity. Fishes recruiting as larvae from the pelagic environment to the reef, rely on information provided by the benthos during habitat selection to detect and interpret a suitable location that will enhance survival and growth. Some fishes utilize a nursery habitat during this vulnerable newly settled stage. The availability of adequate juvenile habitat influences population dynamics and connectivity of reefs. Here, I assess community composition of several coral reefs in Belize, identify important benthic components influencing fish communities, and for two common herbivorous fishes assess habitat preferences and habitat use patterns in possible nursery habitats. Surveyed reefs showed differences in communities between sites with several common benthic components driving dissimilarities. In particular, the soft corals Antillogorgia spp. significantly influenced several fish functional groups. ☐ Surveys of a shallow rubble habitat showed most fish were in the juvenile phase suggesting this area may be a temporary habitat for some species. Specifically, two common herbivores, Scarus iseri, and Acanthurus tractus, utilize this backreef and rubble habitats as juveniles. When tested in a cafeteria style choice experiment, these fish exhibit habitat preferences for benthic species found in rubble habitat but also associated with benthic species found on the reef. This information can be used to help inform lawmakers and conservationists to create more effective strategies when protecting coral reefs. In order to effectively manage the contemporary reefs, it is vital that management strategies consider how the benthic community impacts the fish community and if ecologically important fish display ontogenetic shifts and habitat preferences.University of Delaware, School of Marine Science and PolicyM.S