Characterization of Pacific oyster Crassostrea gigas proteomic response to natural environmental differences

Global climate change is rapidly altering coastal marine ecosystems important for food production. A comprehensive understanding of how organisms will respond to these complex environmental changes can come only from observing and studying species within their natural environment. To this end, the effects of environmental drivers - pH, dissolved oxygen content, salinity, and temperature - on Crassostrea gigas physiology were evaluated in an outplant experiment. Sibling juvenile oysters were outplanted to eelgrass and unvegetated habitat at five different estuarine sites within the Acidification Nearshore Monitoring Network in Washington State, USA to evaluate how regional environmental drivers influenced molecular physiology. We tested the effects environmental conditions at outplant sites and habitat to determine if macrophyte presence and diurnal cycling buffered pH conditions and changed the oysters expressed proteome. A novel, two-step, gel-free proteomic approach was used to identify differences in protein abundance in C. gigas ctenidia tissue after a 29 day outplant by 1) identifying proteins in a data independent acquisition survey step and 2) comparing relative quantities of targeted environmental response proteins using selected reaction monitoring. While there was no difference in protein abundance detected between habitats or within Puget Sound, C. gigas outplanted at Willapa Bay had significantly higher abundances of antioxidant enzymes and carbohydrate metabolism proteins. Environmental factors at Willapa Bay, such as higher average temperature, could have driven this protein abundance pattern. These findings generate a suite of new hypotheses for lab and field experiments to compare the effects of regional conditions on physiological responses of marine invertebrates.