Growth-Associated Ecological Reorganization of the Gut Microbiota in Larimichthys crocea: Shifts in Microbial Persistence and Niche Breadth

Abstract

Simple Summary The intestinal microbiota of Larimichthys crocea changes as fish grow, but these changes do not necessarily follow a simple progression toward a more stable community. In this study, fish from the same cultured population were maintained in the same culture pond and sampled successively at three body-size stages. The dominant bacterial phylum remained broadly conserved, whereas substantial changes occurred at finer taxonomic levels. Persistent microorganisms remained common across the growth sequence but contributed progressively less to total community abundance, while intermittently occurring microorganisms became more quantitatively important. In parallel, microorganisms classified as ecological specialists represented most detected taxa and contributed increasingly to later-stage communities, although generalists remained dominant in overall abundance. These findings show that gut microbiome development in L. crocea involves redistribution of microbial dominance and ecological strategies rather than simple microbial stabilization.