Burnin’ Up for You, Larvae: Larval Thermal Tolerance of the Ochre Sea Star Pisaster ochraceus

Abstract

Marine heatwave (MHW) events cause extreme disturbances throughout coastal marine ecosystems. Studies on these events suggest that MHWs are increasing in frequency and intensity. Our study investigated the survival of P. ochraceus larvae after being acclimated to MHW conditions and estimated their upper thermal limits (LT50) using acute heat exposure (25–34°C). We observed larvae in the ambient non-MHW treatment (13℃) to have a lower LT50 compared to the MHW (17℃) treatments which had a higher LT50. Our results suggest that larvae that were acclimated to MHW conditions are more tolerant to an acute heat shock over 12 h of exposure compared to larvae that were not. As MHWs increase in frequency and intensity, it is imperative to understand how these events will impact marine invertebrates, particularly the early life stages.