A single heat stress bout induces rapid and prolonged heat acclimation in the California mussel, Mytilus californianus

Climate change is not only causing steady increases in average global temperatures but also increasing the frequency with which extreme heating events occur. These extreme events may be pivotal in determining the ability of organisms to persist in their current habitats. Thus, it is important to understand how quickly an organism’s heat tolerance can be gained and lost relative to the frequency with which extreme heating events occur in the field. We show that the California mussel, Mytilus californianus—a sessile intertidal species that experiences extreme temperature fluctuations and cannot behaviorally thermoregulate—can quickly (in 24-48 h) acquire improved heat tolerance after exposure to a single sublethal heat-stress bout (2 h at 30 or 35°C) and can maintain this improved tolerance for up to 3 weeks without further exposure to elevated temperatures. This adaptive response improved survival rates by ~75% under extreme heat stress bouts (2 h at 40°C). To interpret these laboratory ...