Comparative study of the gut microbiota among four different marine mammals in an aquarium

We exploited a natural experiment provided by an aquarium with belugas (Delphinapterus leucas), Pacific white-sided dolphins (Lagenorhynchus obliquidens), common bottlenose dolphin (Tursiops truncatus), and Cape fur seals (Arctocephalus pusillus pusillus). Results show significant differences in microbial community composition of whales, dolphins, and fur seals, and indicate that phylogeny (family level) play the most important role in shaping the microbial communities rather than food and environment. Generally, the gut microbial communities of dolphins had significantly low diversity compared with the whales and fur seals. The gut microbial communities mainly comprise members of Firmicutes and Gammaproteobacteria, together with some from Bacteroidetes, Fusobacteria, and Epsilonbacteraeota. However, different bacterial lineages were chiefly distributed within different marine mammal groups. For instance, Lachnospiraceae, Ruminococcaceae, and Peptostreptococcaceae, were the dominant bacterial lineages in the gut of belugas, while for Cape fur seals, Moraxellaceae, and Bacteroidaceae were the main bacterial lineages. Moreover, gut microbial communities in both Pacific white-sided dolphins and common bottlenose dolphins were dominantly consisted of vast of pathogenic bacteria, such as the Clostridium perfringens, Vibrio fluvialis, and Morganella morganii.