Abstract
Despite an increasing appreciation in the importance of host–microbe interactions in ecological and evolutionary processes, information on the gut microbial communities of some marine mammals is still lacking. Moreover, whether diet, environment, or host phylogeny has the greatest impact on microbial community structure is still unknown. To fill part of this knowledge gap, we exploited a natural experiment provided by an aquarium with belugas (Delphinapterus leucas) affiliated with family Monodontidae, Pacific white-sided dolphins (Lagenorhynchus obliquidens) and common bottlenose dolphin (Tursiops truncatus) affiliated with family Delphinidae, and Cape fur seals (Arctocephalus pusillus pusillus) affiliated with family Otariidae. Results show significant differences in microbial community composition of whales, dolphins, and fur seals and indicate that host phylogeny (family level) plays the most important role in shaping the microbial communities, rather than food and environment. In general, the gut microbial communities of dolphins had significantly lower diversity compared to that of whales and fur seals. Overall, the gut microbial communities were mainly composed of Firmicutes and Gammaproteobacteria, together with some from Bacteroidetes, Fusobacteria, and Epsilonbacteraeota. However, specific bacterial lineages were differentially distributed among the 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 dominated by a number of pathogenic bacteria, including Clostridium perfringens, Vibrio fluvialis, and Morganella morganii, reflecting the poor health condition of these animals. Although there is a growing recognition of the role microorganisms play in the gut of marine mammals, current knowledge about these microbial communities is still severely lacking. Large-scale research studies should be undertaken to reveal the roles played by the gut microbiota of different marine mammal species.
Highlights
Microorganisms, as a resident group that has colonized the mammalian body, especially the gut, outnumber mammalian cells by as many as ten to one, and encode 100-fold more unique genes than the genome of their hosts (Ley et al, 2006)
Thirty-five fecal samples from two whales, four dolphins, and nine fur seals were used in this study to address two questions: (i) what are the gut microbial compositions and diversity of belugas, Pacific whitesided dolphins, and Cape fur seals; what are the similarities and differences of gut microbial community structure and composition of common bottlenose dolphins collected from the aquarium in Sanya, China, with previous studies? and (ii) with the same living environment and food sources, could we find the similar gut microbial communities between different marine mammal species? Of food sources, environment, and phylogeny, which is the most influential factor that shapes the gut microbiota?
A total of 1,927,942 sequences were obtained from 35 fecal samples of different marine mammals after quality assessment, the marine mammals included two belugas, three Pacific white-sided dolphins, one common bottlenose dolphin, and nine Cape fur seals
Summary
Microorganisms, as a resident group that has colonized the mammalian body, especially the gut, outnumber mammalian cells by as many as ten to one, and encode 100-fold more unique genes than the genome of their hosts (Ley et al, 2006). Many physiological processes, such as obesity, energy metabolism, blood pressure, glucose homeostasis, clotting risks, and different behaviors of hosts, are influenced by gut microbiota. The majority of microbes residing in the gut have a profound influence on host physiology and nutrition, both of which are crucial for host health (Bäckhed et al, 2005; Flint et al, 2012). Revealing the gut microbiota of mammals is vital to fully understand the physiological and health status of mammals themselves. The majority of research has focused on the gut microbiota of humans with very limited information on the composition of gut microbiota from other mammals, especially marine mammals, often due to sampling constraints
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
