Characterization of skin- and intestine microbial communities in migrating High Arctic lake whitefish and cisco

At high latitudes, lake whitefish ( Coregonus clupeaformis) and others in the closely related Coregonus species complex (CSC) including cisco ( C. autumnalis and C. sardinella) can be diadromous, seasonally transitioning between freshwater lakes and the Arctic Ocean. CSC skin- and intestine microbiomes were collected, facilitated by Inuit fishers at sites on and around King William Island, Nunavut, at the northern range limits of lake whitefish. Community composition was explored using 16S rRNA gene sequencing and microbiota distinctly grouped depending on fishing site salinity. Overall, lake whitefish intestine communities were more variable than those of the two cisco with higher Shannon diversity, suggesting that lake whitefish and their microbiomes could be susceptible to environmental stress possibly leading to dysbiosis. Lake whitefish showed lower condition (K) in the ocean than in freshwater rivers, whereas cisco condition was similar among distinct seasonal habitats. Taken together, the impact of changing habitats on fish condition and microbial composition may inform approaches to CSC health in fisheries and aquaculture, in addition to being relevant for northern Indigenous peoples with subsistence and economic interests in these resources.