Nurtured by nature: Considering the role of environmental and parental legacies in coral ecological performance

Abstract

The persistence of reef building corals is threatened by human-induced environmental change. Maintaining coral reefs into the future requires not only the survival of adults, but also the influx of recruits to promote genetic diversity and retain cover following adult mortality. Few studies examine the linkages among multiple life stages of corals, despite a growing knowledge of carryover effects in other systems. We provide a novel test of coral parental preconditioning to ocean acidification (OA) to better understand impacts on the processes of offspring recruitment and growth. Coral planulation was tracked for three months following adult exposure to high pCO2 and offspring from the second month were reciprocally exposed to ambient and high pCO2. Offspring of parents exposed to high pCO2 had greater settlement and survivorship immediately following release, retained survivorship benefits during one and six months of continued exposure, and further displayed growth benefits to at least one month post release. Enhanced performance of offspring from parents exposed to high conditions was maintained despite the survivorship in both treatments declining in continued exposure to OA. Preconditioning of the adults while they brood their larvae may provide a form of hormetic conditioning, or environmental priming that elicits stimulatory effects. Defining mechanisms of positive carryover effects, or positive trans-generational plasticity, is critical to better understanding ecological and evolutionary dynamics of corals under regimes of increasing environmental disturbance. Considering parental and environmental legacies in ecological and evolutionary projections may better account for coral reef response to the chronic stress regimes characteristic of climate change.