Assessing the Nursery-Role Function of Pelagic Sargassum for Juvenile Fishes in the Northern Gulf of Mexico

<p><em>Sargassum</em>, a genus of holopelagic brown algae, floats at the ocean’s surface using air-filled bladders and forms a complex comprised of two species, <em>S. natans</em> and<em> S. fluitans</em>. Oceanic processes (e.g., Langmuir circulation, etc.) aggregate <em>Sargassum </em>into mats and weedlines, and primarily distribute the algal complex throughout the North Atlantic Ocean and the Gulf of Mexico (GOM). These floating habitats provide shelter and feeding opportunities for a diverse community of invertebrates and fishes. <em>Sargassum</em> is a presumed nursery habitat for juvenile stages of commercially- and recreationally-targeted fishery species. In this study, I estimated the standardized abundances of juvenile fishes, fish assemblages, and diets of <em>Sargassum</em>-associated fishes in the northern GOM, and investigated temporal, spatial, and environmental variability in these estimates. I observed some interannual variability in fish density and diversity, but species’ distributions were often related to surface chlorophyll, spatial variables, or surface features (Loop Current or associated eddies). Diets were analyzed for juvenile Gray Triggerfish, Greater Amberjack, Lesser Amberjack, Almaco Jack, and Tripletail, and were found to be spatially variable (especially with distance from shelf break). I observed a continuum of dependency on <em>Sargassum </em>for feeding by these different species, from more obligate (e.g., Gray Triggerfish and Tripletail) to transient feeders on the habitat (e.g., Amberjack spp.). The results of this thesis fill a knowledge gap of diet information for <em>Sargassum</em>-associated juvenile fishes in the northern GOM, and provide an understanding of the factors contributing to variability in juvenile fish abundances and assemblages.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Year dc:date.available

2020

Author dc:creator

• Stachowiak, Courtney

Contributors dc:contributor

• Frank Hernandez
• Kevin Dillon
• Mark S. Peterson

• Sargassum
• nursery
• juvenile fishes
• diets
• Gray Triggerfish
• Amberjack
• Aquaculture and Fisheries

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/786

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-1839