The bay scallop, Argopecten irradians, regulates its respiratory activity over a wide range of dissolved oxygen (DO) concentrations at temperatures of 17 C to 22 C (Van Dam 1954). Northern bay scallops, however, are physiologically active at temperatures below 17 C. The potentially significant influence of interactions between environmental variables, such as DO and temperature, on metabolic activity of aquatic animals has been emphasized. A limiting factor such as DO may act to restrict the potential range of activity of an aquatic animal. It was thus the goal of this study to evaluate the possible restricting effect of DO on bay scallop respiration rates at a temperature lower than those examined by Van Dam (1954).