ENVIRONMENTAL INFLUENCES ON COMMON SNOOK (CENTROPOMUS UNDECIMALIS) MOVEMENT IN THE ST. LUCIE ESTUARY

Estuarine ecosystems are dynamic habitats, where the convergence of marine and freshwater results in constant fluxes in environmental abiotic parameters. Organisms must balance these variations within their optimal range to minimize physiological costs, often by movement from unsuitable to more suitable areas. Additional disruptions to ecosystem balances, such as anthropogenic hydrologic discharges, further alter environmental conditions and may cause population-wide movement responses of mobile organisms. Responses to anthropogenic and natural fluctuations can differ based on time of year, life history stage, or individual characteristics. These ecologically-balanced dynamics are difficult to model. In this study, I examined variability in estuarine environmental data and common snook (Centropomus undecimalis) movement responses to anthropogenic and natural fluctuations in the environment in a managed waterway. ARIMA time series models were tested as a method of modeling variability in environmental parameters. Monthly variance was well described throughout most of the estuary, especially when the interannual and intra-annual patterns were stable, indicating that these models are a good method for these types of data and could be appropriate for forecasting. Euryhaline sportfish movement responses to high discharge events in a managed waterway were observed with passive acoustic telemetry and did not show large-scale, population-wide consistency. Responses were variable between and within individuals, but individual characteristics appear to have influenced behavior in response to disturbances. Thus, these sportfish populations may be more resilient to this type of disturbance than previously hypothesized. Generalized additive mixed effects models showed that the distribution and movement of individual fishes varied in response to multiple natural and anthropogenic factors, and there was no primary driver. The understanding of the relationships among the distribution and movement of fishes and abiotic and anthropogenic factors can guide management of waterways and provide insight into how changes will affect abiotic factors and communities.