Meeting Abstract
Corals are currently threatened by a combination of co-occurring stressors brought about by climate change, including warming sea surface temperature, ocean acidification, increasingly frequent disease outbreaks, and storm damage. In order for corals to adapt to this combined challenge at the genetic level, heritable higher tolerance to one stress cannot come at the expense of tolerance to another stress. In other words, corals cannot adapt if genetic tradeoffs among stress tolerances exist. To evaluate the prevalence of such tradeoffs, we exposed replicate fragments of 43 Acropora millepora genotypes to five treatments (control, high temperature, low pH, bacterial challenge, combination). Symbiodinium loss (bleaching), mortality, and growth were measured as fitness proxies. As expected, heat treatment triggered the most symbiont loss and bacterial challenge caused the most mortality. Encouragingly, we did not find any significant tradeoffs; instead, genotypes that remained healthy under one stressor were more likely to remain healthy under other stressors as well. This result suggests that there are no genetic constraints to coral adaptation to climate change.
