Oysters holding their breath: Comparing methodology for measuring the physiological response of Crassostrea virginica

In Texas, the Eastern Oyster, Crassostrea virginica, is an ecologically and economically valuable benthic organism and has been shown to adapt to a variety of environmental changes. However, measuring oyster physiology has proven difficult due to the oyster’s response of closing their shell for long periods of time as a defense mechanism. Therefore, this project aims to test various methods of measuring oxygen consumption rates to determine oyster tolerance thresholds under changing environmental conditions to inform place- based management of oyster farming and restoration. This project will test two methods, the procedure of notching the oyster with a Dremel and a blocking procedure that uses a plastic wedge to prevent the oyster valves from closing shut completely. However, with both these procedures, there is the potential of the oysters becoming stressed which could alter their physiological response during experimentation. Therefore, these techniques will be compared to help researchers understand the impact of additional stress when conducting physiological measurements, with the goal of successfully opening the valves of the oysters to measure oxygen consumption rates over set periods of time. The results of this work will assist in retrieving data on dissolved oxygen consumption rates and oyster shell calcification when exposed to multiple, interacting stressors (i.e., salinity and temperature). Understanding the oyster’s organismal response and tolerance threshold to changing environmental conditions will provide data that supports policy and management of Texas oyster ecosystems.