The Gut Microbiome and its Relationship to Migratory Behaviour and Fate in Wild Fishes

Gut microbiota play an essential role in modulating host physiological processes that contribute to host health and fitness. Wild, migratory species offer a unique opportunity to examine the gut microbiome under an additional layer of complexity. Changing external environments, compounded by migration-associated physiological changes in the host, may be associated with variations in the microbial community and differentially impact fish health and fitness. The objective of this thesis was to investigate the hypothesis that the hindgut microbial communities vary relative to migratory behaviour and fate in wild fishes. Specifically, I assessed hindgut microbial communities in three fish species that exhibit different migratory behaviours using 16S rRNA gene amplicon sequencing: white sucker (Catostomus commersonii), sockeye salmon (Oncorhynchus nerka), and brown trout (Salmo trutta). Further, I highlighted the importance of transitioning to non-lethal sampling methods when studying wild fish microbiomes, especially in relation to studying behaviours. Gut microbial analysis revealed that potamodromous white suckers were dominated by the genus Aeromonas. Further, late migrants were found to be less diverse than individuals arriving during peak migration and contained a significantly different community composition, driven by the genus Mycoplasma. For anadromous migrations, there was weak evidence that the hindgut microbial composition of adult sockeye salmon varied between spawning populations with a relatively short migration (Weaver Creek) versus the most challenging migration (Chilko River). Differential abundances of marine-associated microbes characterized the Weaver population, whereas the potential pathogenic genus Flavobacterium was associated with the Chilko group. Comparatively, Mycoplasma appeared as a dominant taxon across this species. Examining whether the fecal microbiota was associated with migratory status in a partially anadromous juvenile brown trout population revealed no association between the gut microbial diversity or composition and migratory status, though finer-scale site-specific differences were observed. The results presented in this thesis are novel in that they are the first to attempt to characterize the gut microbiome in relation to migratory behaviours and fate in wild fishes. Moreover, this thesis highlights the importance of incorporating a microbial perspective in fish physiology and behaviour research and demonstrates the value of incorporating a holobiont approach.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Biology

Grantor dc:publisher

Carleton University

Year dc:date.issued

2023

Author dc:creator

• Kelly, Lisa A.

Statement dc:rights

• Copyright © 2023 the author(s). Theses may be used for non-commercial research, educational, or related academic purposes only. Such uses include personal study, distribution to students, research and scholarship. Theses may only be shared by linking to the Carleton University Institutional Repository and no part may be copied without proper attribution to the author; no part may be used for commercial purposes directly or indirectly via a for-profit platform; no adaptation or derivative works are permitted without consent from the copyright owner.

Language dc:language.iso

en

DOI

10.22215/etd/2023-15619

OAI identifier oai:identifier

oai:carleton.scholaris.ca:20.500.14718/40821