Date Thesis Awarded

5-2019

Document Type

Honors Thesis

Degree Name

Bachelors of Science (BS)

Department

Biology

Advisor

Emily Rivest

Committee Members

Jonathan Allen

Paul Heideman

Rowan Lockwood

Abstract

Oysters are a critical part of the Chesapeake Bay ecosystem, so it is important to understand how they might respond to increasingly variable and potentially stressful environmental conditions. This study aimed to investigate the links between environmental history and oyster physiology in order to understand how oysters might perform in future conditions. The objectives of this study were to (1) examine how environmental history might influence oyster physiology, (2) evaluate how environmental history might influence physiological stress responses, (3) assess the relative importance of distal and proximal environmental history on oyster physiology, and (4) determine the relative importance of distal and proximal environmental history on physiological stress responses. Oysters were deployed at four different sites from July to November 2018. After that period, half of the oysters at each site were collected for analysis, and the other half were redeployed in common garden conditions for one month prior to collection and analysis. After each collection, some oysters from each group were analyzed for glycogen and condition index analysis, while other oysters were subjected to an acute salinity exposure. After the exposure, total antioxidant potential was measured. Water quality was measured throughout field deployments and experimental treatments. Oysters from different sites had different physiological conditions, demonstrating that environmental history influenced physiology. However, oysters from different sites responded similarly to different acute salinity exposures, suggesting that environmental history may not influence stress physiology or that the experimental exposures did not induce stress. After common garden conditions, the physiological states of the oysters changed in different ways from their initial states. However, some physiological traits experienced similar changes from their initial states after common garden condition, indicating that portions of environmental history can affect physiological components in a variety of ways. The site of an oyster’s initial deployment affected how stress responses changed from their initial states in response to common garden conditions; the significance of site indicates that distal history may play a significant role in shaping physiological stress responses. The acute salinity exposure did not have an effect on the change in stress responses from their initial states in response to common garden conditions, suggesting that the experimental treatments may have been insufficient in inducing a stress response. By utilizing knowledge about environmental history and its influence on an oyster’s physiological state, better predictions can be made concerning how oyster health and performance might be shaped by future environmental conditions under climate change.

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