Temperature-driven secondary competence windows may increase the dispersal potential of invasive sun corals

Abstract

Invasive sun corals exhibit outstanding development plasticity during early ontogenesis, which may greatly affect the pelagic duration of propagules and hence their dispersal potential. Remarkably, a small proportion of larvae may not directly settle on the benthic habitat, but metamorphose to planktonic polyps. We show the latter may settle successfully, eventually opening a secondary competence window (SCW). Based on local conditions (Southeast Brazil), delayed SCWs were confirmed at average summer (26 °C) and, especially, at heat-wave (30 °C) temperature, allowing an escape response from habitats where larval mortality rates are high and mass-mortality events of colonies, later on, more likely. Despite a higher frequency of pelagic metamorphosis, no SCWs were observed at average winter (22 °C) and cold-front (19 °C) conditions. Climate change may thus favor large-scale dispersal of competent pelagic polyps and further extensions of the leading range edge to subtropical and warm temperate regions where temperature conditions (ca. 22 °C) for propagule survival and settlement success are best.