Meeting Abstract
Predicting the effects of climate change on organisms’ physiology, fitness, and potential geographical distribution relies on a clear understanding of the effects of temperature on fitness measures. While organisms live in environments that regularly fluctuate in temperature, most studies on temperature sensitivity have focused on the effects of constant temperature conditions, which may have very different physiological effects. In this study we compared the responses of the bay mussel Mytilus trossulus from Tofino, British Columbia (outer coast) and Port Moody, British Columbia (inner coast) to either six weeks of constant temperature acclimation at 6, 12, or 18 °C or to temperatures that regularly fluctuated between 6 and 18 °C (with a mean of 12 °C). In a diverse suite of fitness measures (feeding and heart rate, growth rate, survival, and byssal thread production), we found that responses to variable temperatures were always significantly different than to constant temperature acclimation. In addition, each population showed unique responses to thermal acclimation, with mussels from Tofino being generally less sensitive to temperature than the mussels from Port Moody. These results suggest that projections of species responses to climate change based on experiments involving constant temperatures are likely to inadequately capture the complexity of responses under more natural, fluctuating conditions.
