Corals and climate change : exploring heat tolerance and adaptation potential across ecological scales

Abstract

Coral reefs are facing continued declines under climate change due to marine heatwaves and catastrophic bleaching and mortality events. For coral assemblages to continue providing ecological services and supporting biodiversity, corals will need to adapt. Yet, it remains uncertain whether the rates of adaptation can keep pace with ocean warming. Here I address this knowledge gap at different levels of biological organisation for the coral assemblages of Palau, Micronesia, tackling questions pertinent to improving predictions of coral reef futures under climate change, and designing climate-smart management solutions. Have coral assemblages already adjusted to ocean warming and, if so, how does this alter possible future mass coral bleaching scenarios? How variable is coral heat tolerance within species populations, and what does this mean for adaptive potential? Do trade-offs exist between coral host heat tolerance and other fitness related traits that could hinder adaptation? To what extent is coral heat tolerance influenced by local-scale variations in thermal stress regimes? Alone, is natural selection sufficient to keep pace with warming? In this body of work, I tackle these questions and challenge some of the paradigms in coral reef ecology using a combination of field and lab experiments, historic environmental and ecological survey data, and future greenhouse gas emissions scenarios from global climate models. Together, this work uncovers new insights into the adaptive capacity of corals, suggesting that coral reef ecosystems may yet have untapped reservoirs of resilience, but that rapid action on climate change is still required to secure a future for these ecosystems