Ecological disturbances alter biotic communities and ecosystems. In many coastal zones disturbances are increasing, including algal blooms, storms, hypoxic events, and fish kills. These disturbances are often related, for example blooms releasing toxins or depleting dissolved oxygen, ultimately killing fish. Depending on the intensity, duration, and geographic extent of a disturbance, the fish community can take days to years to recover from disturbances. To explore the relationships among environmental disturbances, sport fish, and forage fish communities, this thesis examined two Florida estuaries with differing disturbance regimes. Using an ensemble modelling approach combining generalized linear models (GLM), Bayesian modelling, and Bayesian structural equation modeling (SEM), this complementary framework helped elucidate complex relationships among environmental variables and the fish community following a disturbance. In Banana River, both sport fish and forage fish abundances decreased following an algal bloom, but the decrease in abundance of forage fish was more rapid. Forage fish community dynamics were more closely associated with water quality metrics than sport fish communities during non-disturbed periods (December- March). However, during the algal bloom, sport fish community dynamics were more closely associated with water quality metrics than forage fish community dynamics. In the three months following the kill, the forage and sport fish communities were less strongly linked than in non-disturbed years. In the chronically stressed St Lucie Estuary, fish community dynamics and water quality were weakly linked from 2015 - 2019. These shifts in community dynamics and relationships following a disturbance suggest forage and sport fish communities, food webs, and trophic dynamics may be at increased risk of surpassing an ecological threshold as algal blooms become more common. Furthermore, the decoupling documented in fish communities and abiotic environment in the chronically stressed St. Lucie Estuary suggest this region may have already passed an ecological tipping point.
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Master of Science (M.S.)
College of Sciences
Length of Campus-only Access
Masters Thesis (Open Access)
Lewis, Dakota, "Assessing the Role of Disturbance in Estuarine Fish Community Dynamics" (2021). Electronic Theses and Dissertations, 2020-. 520.