Reduce Local Stressors to Potentially Increase Coral Resilience to Climate Change

Grant Winners

Dean

Abstract

Coral reef ecosystems have declined globally in the past decades and continue to decline at alarming rates. The decline is the result of high coral mortality coupled with the inability to recover or slow recovery after disturbances. For coral populations to recover, the larvae produced by corals on undisturbed reefs must be transported by ocean currents to the disturbed areas, successfully settle and grow to the adult stage. A major impediment to recovery are anthropogenic stressors, such as pollution and terrestrial sediment and nutrient run-off, to which coral larvae and juveniles are particularly sensitive. On top of local stressors, corals and the ecosystems they sustain are now also threatened by climate change, an impact which can only be fully tackled with global actions. Thus, the challenges now posed to local conservation managers are greater as their sphere of action is limited locally. Nevertheless, research has shown that animals with greater energy reserves are better able to cope with climate change. Therefore, one possible course of action to reduce the impact of climate change is to reduce the magnitude of local stressors, e.g. reduce sediment concentrations which limit photosynthetic ability in corals, enabling corals to allocate more energy towards coping with climate change. In this study we will investigate if coral resilience to climate change may be ameliorated through the reduction of a local stressor. Experiments to quantitatively assess the synergistic effects of sediment concentration and increased temperature on the survival and growth of juveniles of the coral Favia fragum will be conducted at the Oceanographic Center. This study will increase our understanding of the environmental factors that hinder the recovery of coral populations and inform policy makers and managers of the most effective management actions, specifically, maximum sediment input allowances, necessary to increase coral recruitment success under climate change scenarios.