The gut within: reframing the coral gastrovascular cavity as a discrete anaerobic microbial ecosystem.

The coral gastrovascular cavity (GVC) functions as a distinct anaerobic microbial ecosystem with its own redox regime, substrate supply, and bacterial community.

• Why it matters: Understanding the spatial microenvironments within coral holobionts is crucial because it influences microbial metabolism and symbiotic interactions, which are often overlooked in broader studies.
• What they did: Microsensor work involving coral GVCs demonstrated active anaerobic metabolism, indicating the GVC sustains a specialized, gut-like microbial ecosystem with specific redox and substrate conditions.
• The result: Recognizing the GVC as a discrete ecosystem emphasizes the need for spatially explicit research approaches to better resolve coral metabolism at microscopic scales.