Eastern oysters (Crassostrea virginica) are a valuable commercial and recreational fishery, as well as an important ecosystem engineer in coastal systems, providing habitat for an array of marine organisms and improving water quality by removing excess nutrients such as nitrogen. Oysters filter nitrogen-rich plankton as they feed and assimilate it into their tissue and shell (bioaccumulation), thereby removing nitrogen from the system. Their ability to remove and store nitrogen can be affected by the environment, as oysters eat and grow differently depending on the conditions they are exposed to. Climate change is affecting environmental conditions in shallow water systems where oysters live, potentially influencing their ability to deliver this ecosystem service. Specifically, dissolved oxygen is declining in shallow water estuaries like the Chesapeake Bay, driven in part by rising water temperatures associated with climate change. The interactive effects of warming and low dissolved oxygen on oyster growth and nitrogen storage are therefore critical to understanding how climate change will affect coastal systems.
We conducted a manipulative laboratory experiment that quantified how low dissolved oxygen (hypoxia) and warming affects the growth and nitrogen storage of juvenile eastern oysters. Early life stages are often particularly sensitive to environmental stress and changes that occur early in life may have persistent effects later in life. We hypothesized that when exposed to warming and hypoxia alone, oysters would grow less and store less nitrogen, but that exposure to warming and hypoxia together would have no effect on growth or bioassimilation of nitrogen, in accordance with previous studies. This talk will explore these effects and discuss how changes in oyster performance driven by climate change would impact their ability to deliver ecosystem services.