Succession of the yellow tang (Zebrasoma flavescens) microbiome from hatch to settlement in a recirculating aquaculture system.

Ornamental fish aquaculture is receiving increasing scientific attention as a sustainable means of meeting demand for reef species from the aquarium trade. However, low juvenile recruitment in an aquaculture environment remains a key industry bottleneck for many high-demand pelagic-spawning species. Here, the microbiome of a yellow tang (Zebrasoma flavescens) larval cohort from hatch to the juvenile stage (76 days post-hatch) in a recirculating aquaculture system was investigated using a high throughput 16S rRNA gene amplicon sequencing approach. The taxonomic composition of microorganisms was assessed from the gastrointestinal tract of larval yellow tang, their feed, and the recirculating rearing water at eight key developmental timepoints. We observed a dynamic larval microbiome that displayed developmental stage-specific signatures. While some microbial taxa were ubiquitous throughout the larval stage (i.e., Proteobacteria), others, including Fusobacteriota, were restricted to specific growth stages. In addition to the role of ontogeny on host microbiomes, shifts in the microbial communities associated with feed types were found to coincide with pronounced changes in specific bacterial genera obtained from larval-derived microbiomes. Notably, in larval samples the relative abundance of the genus Vibrio peaked at 36 and 55 days post-hatch (97.2% and 94.2%, respectively), coinciding with the addition of enriched Artemia franciscana brine shrimp into their diet. The introduction of Vibrio species from prey cultures, specifically with Artemia, highlights that feed-associated microbiomes may play a substantial role in determining host microbiomes in early life, and illustrates the importance of further understanding the nature of Vibrio species present in food items used in an aquaculture setting.