Diet-induced shifts in the crown-of-thorns (Acanthaster sp.) larval microbiome

Abstract

Predation by the crown-of-thorns seastar (CoTS; Acanthaster sp.) is a pervasive stressor attributing to the decline of coral reefs. These outbreaks are suggested to be linked to eutrophy-driven recruitment pulses, where increased nutrients enhance larval success. CoTS larvae, however, are tolerant of oligotrophic conditions typical of tropical ecosystems and outbreaks occur in regions isolated from eutrophy, highlighting the resilience of these larvae to oligotrophic conditions. Here, we test the hypothesis that CoTS larvae associate with bacterial communities that are dynamic across an oligotrophic–eutrophic continuum and are specific to each feeding regime. Our analysis of the CoTS larval microbiome suggests that CoTS larvae associate with a bacterial community distinct from the environmental microbiota and that this community experiences a community-level shift in response to differential feeding that is maintained over development. Symbioses with a diverse and dynamic, and a potentially phototrophic, bacterial community may contribute to resilience of CoTS larvae that enable the success of CoTS and, perhaps, other tropical marine larvae in oligotrophic seas.