Population-Specific Responses to Interspecific Competition in the Gut Microbiota of Two Atlantic Salmon (Salmo salar) Populations
The gut microbial community in vertebrates plays a role in nutrient digestion and absorption, development of intestine and immune systems, resistance to infection, regulation of bone mass and even host behavior and can thus impact host fitness. Atlantic salmon (Salmo salar) reintroduction efforts into Lake Ontario, Canada, have been unsuccessful, likely due to competition with non-native salmonids. In this study, we explored interspecific competition effects on the gut microbiota of two Atlantic salmon populations (LaHave and Sebago) resulting from four non-native salmonids. After 10 months of rearing in semi-natural stream tanks under six interspecific competition treatments, we characterized the gut microbiota of 178 Atlantic salmon by parallel sequencing the 16S rRNA gene. We found 3978 bacterial OTUs across all samples. Microbiota alpha diversity and abundance of 27 OTUs significantly differed between the two populations. Interspecific competition reduced relative abundance of potential beneficial bacteria (six genera of lactic acid bacteria) as well as 13 OTUs, but only in the LaHave population, indicating population-specific competition effects. The pattern of gut microbiota response to interspecific competition may reflect local adaptation of the host-microbiota interactions and can be used to select candidate populations for improved species reintroduction success.
Keywords16S rRNA Gut microbiota Interspecific competition Non-native species Reintroduction Salmonid
This project was funded by the Natural Sciences and Engineering Council of Canada (Discovery Grants and Strategic Project Grant). We thank A.L. Houde, C. Wilson, W. Sloan, S. Ferguson, B. Lewis, A. Smith, C. Black, H. Dokter, J. Van Zwol, S. Garner, T. Hain, M.C. Bellmare, M.H. Greffard, H. Allegue, K. Gradil, M. Lau, Z. Yang, M. Browning, I. MacKenzie, and J. Laycock for their support and assistance in semi-natural stream construction, fish breeding, fish feeding, sample collection, and other help at the Ontario Ministry of Natural Resources (OMNR) Codrington Research Facility. We thank R. Hepburn for assistance in sequencing the bacterial 16S rRNA gene library.
XH conducted field and lab work, performed data analyses, and wrote the first draft of the paper. SRC provided the 16S rRNA gene primers and helped with the interpretation of the microbial community data. DDH supervised this study. All authors contributed to the final version of this paper.
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