Similarities and differences in gastrointestinal microbiomes between wild and human-cared spotted dolphins (Stenella attenuata) in natural waters

Abstract

Despite the growing awareness on the importance of gut microbiomes, understanding marine mammal gut microbiomes remains limited due to difficulties in sampling. Spotted dolphins (Stenella attenuata) are widely spread oceanic cetaceans, and there is a gap in knowledge regarding their gut microbiology. In this study, we opportunistically collected samples from both wild and human-cared spotted dolphins in the southern waters of Hainan Island, China. This provided the opportunity to examine the composition and diversity of the gut microbial communities of this cetacean species. Since these dolphins inhabit a similar water environment, different food sources might be the primary factor distinguishing the gut microbiomes of wild and human-cared populations, offering valuable experimental material to investigate potential differences in gut microbial community structure among marine mammals in similar environments but with varying food sources. We found that the gastrointestinal microbial community structure of wild and human-cared dolphins demonstrated significant differences, both overall and at specific locations. However, no significant difference was observed in the microbial diversity of their gastrointestinal tracts, indicating that the disparities primarily lie in microbiota composition. Additionally, we detected numerous potentially pathogenic bacteria, suggesting a comprehensive future study of marine mammal gut microbiology. Such a study might involve determining health indicator factors associated with these microbiomes. Our study not only supplements information on the gut microbiology of spotted dolphins but also delves into the similarities and differences in gastrointestinal microbial communities within the same marine mammal species when food source variations play a significant role in their lives.