Taxonomic novelty emerges more frequently and independently of functional novelty in historical coral communities

Abstract

Earth's ecological assemblages are rapidly being driven towards unprecedented, novel states. We know little about ecological novelty in our oceans, limiting our ability to detect, contextualise, and manage substantive anthropogenic change. This is especially true for novel states with altered functional compositions. Here, we provide a quantitative assessment of taxonomic and functional ecological novelty in historical coral communities across the east Australian coast, capturing changes in the composition of coral taxa and their traits over the past 1500 years. Taxonomically novel communities emerged more frequently and often unaccompanied by substantial trait compositional change while functional novelty was commonly observed alongside significant genus turnover. Novel coral communities themselves were rare, context-dependent, and often associated with transitions in dominant genera. Our preliminary trait-based community classifications complement classical taxonomic methods to uncover a history of ecological change in east Australian coral communities, helping provide important context for their present states and inform future responses under ongoing and intensifying human-driven change.