The feasibility and challenges of building coral reef resilience through assisted evolution

Background/Question/Methods: Coral reefs are diverse tropical marine ecosystems that have suffered massive declines in health and abundance as a result of climate change and local, direct anthropogenic disturbances. Reef coral ecological trajectories clearly indicate that the rates, the magnitudes, and the complexity of environmental change are overwhelming the intrinsic capacity of corals to adapt and survive. Although the future looks grim, some corals and coral reefs are surviving and even thriving in conditions that kill others. The current state of knowledge suggests that these thriving corals and reefs have higher thresholds for environmental disturbance as a result of some combination of genetics, environmental experience, and the taxonomic composition of their obligate endosymbiotic dinoflagellate communities. Here we draw on advances in other fields to examine the feasibility of actively augmenting the capacity of reef corals to tolerate stress.

Results/Conclusions: We propose a series of experiments that leverage and naturally accelerate rapid adaptive mechanisms in corals, an approach known as (human)-assisted evolution (AE). These experiments include: 1) inducing acclimatization or epigenetic response mechanisms, 2) evolving symbionts, 3) shuffling and/or switching symbiont communities, and 4) selective breeding of corals. The goal of these activities is to develop stocks of corals with enhanced stress tolerance that can be used to build resilience on depauperate reefs, to restore damaged reefs and to “green” existing grey structures. We discuss the strengths, weaknesses, opportunities, and threats to applying AE to reef corals and highlight the broad community discussion that will frame the success of biological interventions aimed at preserving or restoring coral reef resilience and sustaining the associated human goods and services that reefs provide.