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Hamilton, B. R. (2022). Species-Habitat Relationships and Multi-Source Feeding in Apalachicola Bay Fishes: Implications for Management. Retrieved from https://purl.lib.fsu.edu/diginole/2022_Hamilton_fsu_0071N_17048
Coastal areas serve as vital habitat for many marine fishes. Estuaries are a type of coastal system in which freshwater input often drives broad gradients of environmental variables while transporting fluvial nutrient subsidies to marine systems. Increased nutrient levels contribute significantly to estuarine productivity, while wide ranges of abiotic conditions provide a diverse collection of environmental niches on both spatial and temporal scales. We aimed to understand the influence of environmental variables on the distribution and abundance of fishes as well as the contribution of various nutrient sources to fish biomass, both of which are necessary information for devising appropriate management strategies for commercially and recreationally exploited species in coastal systems. We documented large fish community structure in the Apalachicola Bay system (ABS) from 2018 to 2021 using fishery-independent longline and gillnet surveys. Spatiotemporal variation in fish assemblages was evaluated with permutational multivariate ANOVA, while community- and species-level habitat relationships were described across gradients of environmental variables with non-metric multidimensional scaling and generalized additive models. With samples collected from these surveys, we used carbon (δ 13C) and sulfur (δ 34S) stable isotope mixing models to identify the contribution of prey sources in a fluvial-dominated estuarine habitat relative to nearby seagrass and offshore reef habitats to five species of migratory shark. Fish communities varied spatially throughout the system, and changes in these communities were most strongly correlated with gradients in salinity, clarity, and depth. Sharks exhibited a strong reliance on prey from fluvial-dominated habitat with the youngest individuals displaying the highest reliance relative to larger individuals. We documented higher species richness and density of young elasmobranchs in our surveys compared to adjacent systems, supporting past suggestions that this area serves as important juvenile shark habitat. These findings illustrate the importance of a fluvial-dominated estuarine system to migratory marine predators in providing both habitat and important nutrient sources, especially in early life-stages. Changes to river-flow regimes could disrupt both the availability of diverse niches along a gradient of river-influence and the transport of fluvial nutrients to coastal marine systems, ultimately impacting migratory predator populations and their role in transporting these nutrients across the seascape.
A Thesis submitted to the Department of Biological Science in partial fulfillment of the requirements for the degree of Master of Science.
Bibliography Note
Includes bibliographical references.
Advisory Committee
Ralph D. Grubbs, Professor Directing Thesis; Thomas Miller, Committee Member; Joe Travis, Committee Member.
Publisher
Florida State University
Identifier
2022_Hamilton_fsu_0071N_17048
Hamilton, B. R. (2022). Species-Habitat Relationships and Multi-Source Feeding in Apalachicola Bay Fishes: Implications for Management. Retrieved from https://purl.lib.fsu.edu/diginole/2022_Hamilton_fsu_0071N_17048