Thermal suppression of gametogenesis explains historical collapses in larval recruitment

Abstract

AbstractProjections for population viability under climate change are often made using estimates of thermal lethal thresholds. These estimates vary across life history stages and can be valuable for explaining or forecasting shifts in population viability. However, sub-lethal temperatures can also lead to declines in vital rates and ultimately shape fluctuations in the reproductive viability of populations. For example, anomalous climatic events can suppress reproduction and lead to recruitment failure well before early life stages or adult stages become affected. These sub-lethal impacts make the effects of climate change more severe than lethal thresholds predict. Despite a growing awareness of this issue, tying sub-lethal effects to observed recruitment failure remains a challenge especially in marine environments. Here, we experimentally show that sub-lethal thermal suppression of female gametogenesis offers a plausible explanation for historical collapses in sea urchin recruitment during marine heatwaves. These sub-lethal thermal sensitivities of reproduction can narrow the thermal envelope for population viability compared to what lethal limits predict.