Marine heatwaves impact organism developmental time

Understanding the effect of marine heatwaves on organisms is central for improving climate change predictions. Even moderate heatwave events are likely to drive performance of organisms especially if they are long relative to the life cycle duration. In ectotherms, such events will affect biological time on a stage-dependent basis; they could alter the timing of life cycle events (e.g. spawning, reproduction) and cause reproductive failure. We use a mathematical framework to explore three different scenarios for the causal relationship between temperature and developmental time and help future experimental research. Here, we highlight the need to experimentally test for (1) stage-dependent responses to temperature and (2) plastic responses to the thermal history. (3) Consider traits linked to developmental time (e.g. body size) and (4) integrate across levels of organization to develop stronger explanatory models. Experiments need to manipulate the timing, duration, and magnitude of warm events.