Positive associations between growth and thermal tolerance in the reef-building coral Montipora capitata

Abstract

Relationships between ecologically important traits are increasingly important for the future of coral reefs, which are declining globally due to a variety of stressors. Corals that resist and recover from bleaching will be selected under future climates, which may negatively or positively impact a range of associated traits important for the structure and function of contemporary and future reefs. Using standardized assays, we investigated growth under ambient conditions, bleaching resistance and recovery after bleaching in a model population of 60 Montipora capitata colonies harboring diverse symbiont communities. We found significantly higher trait variance within Durusdinium-dominated colonies, highlighting the interaction of host and symbiont. We also show that symbiont community impacted thermal tolerance and survivorship during the thermal stress assay, but not recovery or growth. There was also a positive relationship between thermal tolerance and change in surface area and thermal tolerance and recovery from equivalent amounts of stress. These results demonstrate limited tradeoffs to thermal tolerance and suggest that bleaching tolerant corals in this model system are suited to recover from stress and maintain high growth rates under ambient conditions, providing insight into the adaptive capacity of thermally tolerant corals in the Anthropocene.