Ocean spatial geography drives the midgut microbial composition of marine fish

Abstract

Having emerged 600 million years ago, fish represent the largest diversity of vertebrates and have adapted exceptionally to continuous changes in the aquatic ecosystems. Despite their importance, fish have been significantly underrepresented in microbial ecology analyses and little is known about the environmental drivers of the fish gut microbial composition. To investigate the relationship between habitat depth and distance from shore in driving fish gut microbial composition, we analysed and compared the microbiota of the midgut and hindgut of marine fishes. Our study found that water depth and distance from shore do interact to drive fish microbial composition in midgut samples, but not in hindgut samples. We also found that genera associated with nutrient cycles (Rhodopiruella, Desulfotalea, Sva0081, Milano WF1B-44, Woeseia, Sulfurovum, and Massilia) and water pollution (Fluviicola, Ulvibacter, Fluviicola, and Rhizobium) can be reflected in the midgut microbial composition of marine fish. These findings provide a reference for future studies of the gut microbiome of fish as well as insights into the key role of spatial geography of the host habitat in influencing gut microbial composition.