Host-associated microbiomes and their roles in marine ecosystem functions

The significance of mutualisms between eukaryotic hosts and microbes extends from the organismal to the ecosystem level, and mutualistic symbioses underpin the health of Earth’s most threatened marine ecosystems. Despite rapid growth in research on host-associated microbes (microbiomes), very little is known about their interactions for the vast majority of marine host species. We outline research priorities to broaden our current knowledge of host-microbiome interactions and how they shape marine ecosystems. We argue that this research frontier will allow us to predict responses of species, communities, and ecosystems to stressors driven by human activity, and inform future management and mitigation.