Date of Award
Spring 2026
Document Type
Thesis
Degree Name
Master of Science (MS) in Biology
Department
Biology
Committee Chair
Dr. Lori Tolley-Jordan
Abstract
Coral reef ecosystems support highly diverse fish assemblages that are strongly influenced by habitat structure and environmental conditions. Understanding how fish communities vary across habitat types is critical for effective monitoring and management. This study evaluated habitat-associated patterns in reef fish assemblages around St. Croix, U.S. Virgin Islands, using stationary underwater video data collected through the Southeast Area Monitoring and Assessment Program (SEAMAP) Caribbean.
A total of 37 video deployments were analyzed across coral (n=20), macroalgae (n= 9), and sand habitats (n=7), with seagrass (n=1) included for descriptive purposes only. Fish abundance was quantified using the MinCount metric, and taxon richness and total abundance were compared among habitats using Kruskal–Wallis tests. Multivariate community composition was assessed using Bray–Curtis dissimilarity, permutational multivariate analysis of variance (PERMANOVA), and non-metric multidimensional scaling (NMDS).
Taxon richness and total abundance differed significantly among habitat types. Coral and macroalgal habitats support higher richness and abundance than sand habitats. Multivariate analyses revealed significant differences in community composition among habitats, indicating that habitat type plays a key role in structuring reef fish assemblages. Coral and macroalgal habitats exhibited greater variability in assemblage structure, while sand habitats supported more uniform communities.
The use of standardized underwater video methods provided a consistent, non-invasive approach for assessing fish communities across habitats and yields valuable data for long-term monitoring and fisheries management in the U.S. Caribbean. These findings highlight the importance of habitat structure in shaping reef fish assemblages and underscore the ecological value of structurally complex habitats.