Walther, BenjaminRandall, Jessica2023-10-242023-10-242023-08https://hdl.handle.net/1969.6/97607A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Fisheries and MaricultureThis study aimed to investigate the resilience of eastern oysters (Crassostrea virginica) exposed to environmental stressors such as droughts and floods. The primary objectives were to assess the potential of geochemical records within oyster shells to discern past environmental variability and to evaluate the growth performance of these oysters in dynamic, subtropical estuarine systems subject to these major climactic events. Eastern oysters have been established as reliable bioindicators of water quality and records of their native habitats. Previous studies utilizing stable isotopes (?13C and ?18O) to track freshwater inflow patterns faced challenges due to multiple covarying factors. This study employed Ba/Ca ratios as an alternative proxy and examined their relationship with salinity. Notably, shell ?13C values demonstrated a remarkable match with estimated salinity values, highlighting the usefulness of this chemical proxy alone or in combination with ?18O for similar investigations. Despite their resilience, oyster growth performance can be adversely affected by environmental disturbances. Oysters from low, fluctuating salinity environments exhibited the greatest shell growth, followed by those inhabiting intermediate, then high, stable salinity environments. Which suggests that freshwater inflows following flood events positively influence estuarine functioning and oyster health, likely due to increased water turbidity, food availability, and reduced susceptibility to predation and disease. With projections of drier climates and variable precipitation patterns leading to more extreme temperature and salinity levels, eastern oysters may face greater growth limitations in the future. Therefore, understanding how environmental disturbances, including freshwater inflow dynamics, differentially impact oyster growth is crucial for the management and protection of this increasingly vulnerable keystone species.151 pagesen-USThis material is made available for use in research, teaching, and private study, pursuant to U.S. Copyright law. The user assumes full responsibility for any use of the materials, including but not limited to, infringement of copyright and publication rights of reproduced materials. Any materials used should be fully credited with its source. All rights are reserved and retained regardless of current or future development or laws that may apply to fair use standards. Permission for publication of this material, in part or in full, must be secured with the author and/or publisher.bariumeastern oysterestuaryfreshwater inflowmorphometricsstable isotopesText