Physiological Responses to Water Temperature and Flow in Three Marine Mussel Species

Abstract

Many marine organisms must contend with the physiological challenges associated with warming water temperatures. This is especially true in nearshore ecosystems where organisms often live near their thermal limits. However, physiological responses to thermal stress may vary depending on local flow conditions that can influence rates of gas exchange with surrounding waters. As such, I examined the influence of both water temperature and flow on respiration rate in Mytilus californianus and compared the responses to those found in two congeneric M. trossulus, and M. galloprovinicalis. Aquatic respiration rates were quantified at five different temperatures (5, 11, 17, 23, and 29 °C) and water velocities (2, 4, 6, 10, 20 cm s-1) in a fully factorial design. Respiration was highest in M. californianus, followed by M. trossulus, and the lowest rates were measured in M. galloprovincialis. Respiration rates in M. californianus were relatively consistent under different temperatures and flows, whereas M. trossulus and M. galloprovincialis displayed optimal peak patterns. We discuss these physiological patterns in the context of their different ecologies.