Rachel C. Neil, J. Barton, Andrew Heyward, David S. Francis, Leo Nankervis, Thomas S. Mock, Craig Humphrey, David G Bourne
Associations with fish can benefit corals by increasing growth and stress tolerance. To investigate microbial and nutritional responses of corals to fish associations in the context of enhancing coral aquaculture outcomes, Pocillopora verrucosa were cultured for 3 months with different combinations of live feeds and schools of juvenile Chromis viridis damselfish. The combined live feeds and fish treatment resulted in a bacterial community most similar to wild P. verrucosa, dominated by Endozoicomonas-affiliated taxa. Protein content was enhanced in corals with access to live feeds and/or dissolved fish wastes compared to unfed controls. Total lipid concentrations were elevated in captive corals with access to dissolved fish wastes and at moderate levels in those supplied live feeds, likely due to the activity of corals' symbionts and deposition of derived lipids from live feeds, respectively. However, all captive corals demonstrated a significant reduction in storage lipid concentration compared to samples from the wild. Fatty acid analysis indicated these shifts were likely the result of higher light levels in the field supporting Symbiodiniaceae photosynthesis and potentially feeding on wild zooplankton. Co-culturing captive corals with fish and providing appropriate live feeds may therefore offer an effective approach to improve coral nutrition, health and microbiome stability.