Distinct intestinal microbial communities of two sympatric anadromous Arctic salmonids and the effects of migration and feeding

Abstract

Although intestinal microbial communities from anadromous Arctic char (Salvelinus alpinus (Linnaeus, 1758)) in Kitikmeot, Nunavut, Canada, differ depending on the timing and location of capture, determinants of gut microbiota in other wild Arctic salmonids are largely unknown. Using high-throughput 16S rRNA gene sequence data, we compared intestinal microbiota from Arctic char to those from a related and sympatric salmonid, lake whitefish (Coregonus clupeaformis (Mitchill, 1818)). Shifts in lake whitefish gut microbial community composition were observed between brackish water and freshwater, similar to impacts of salinity reported previously for Arctic char. Despite these similarities, gut community profiles for the two salmonids differed, with whitefish having higher diversities and increased proportions of taxa affiliated with potential pathogens. Geography seemed to have a greater impact on freshwater whitefish gut microbiota than on corresponding Arctic char. Additionally, microbiota diversity was significantly more affected by feeding behavior in whitefish compared with sympatric Arctic char. As sampled whitefish were at their northern range limits and grew slowly, we speculate that they, and their microbial consortia, could be more vulnerable to certain abiotic and biotic factors than Arctic char, which are well adapted to conditions found in these high latitude environments and have the most northern distribution of any freshwater fish.

Impact of Putative Probiotics on Growth, Behavior, and the Gut Microbiome of Farmed Arctic Char (Salvelinus alpinus)

“…This is the first study characterizing the gut microbiota of farmed Arctic char. Compared to previous studies on wild Arctic char, the farmed fish appear to harbor a lower number of permanent members of the gut microbiota, but partially share the presence and high relative abundance of Mycoplasma and Brevinema (Hamilton et al, 2019;Element et al, 2020Element et al, , 2021. Probiotic treatment did not affect the relative abundance of the three dominant taxa in this study, with the exception of C. maltaromaticum SF1944 which was associated with a significantly reduced relative abundance of the Brevinema sp., possibly due to competition for the same niche.…”

Correlation of Mercury Occurrence with Age, Elemental Composition, and Life History in Sea-Run Food Fish from the Canadian Arctic Archipelago’s Lower Northwest Passage

“…This association was further confirmed when the salmonids were pooled and analyzed together, showing a positive rank correlation between THg and age (Spearman test, DF = 319, p = 0.56), as shown in Figure 2. The otolith age data, used to develop an incremental growth standard for each of the fish groups (Supplementary Table S1), showed no deviation from growth standards for ocean-caught and freshwater-caught fish from this region, as previously reported [54,55]. Notably, growth analysis showed that over the sample age range, Arctic char were uniformly faster growing, followed by lake trout, with cisco and lake whitefish being similar, but with the latter attaining a considerably greater age than the former (Supplementary Table S1).…”

“…THg levels are clearly influenced by phylogenetics, as shown by the PCA that highlighted the segregation of different species into different quadrants. Analysis of the genetic and microbiome differences [18,54,55] between these salmonids may be a future promising avenue to reconcile some of the disparities in our understanding of tissue concentrations of THg in different salmonids. In addition, it is our hope that the Uqsuqtuuk community will continue to access Arctic char, lake whitefish, and cisco as healthy food choices and as a resource for economic benefits.…”

Antibiotic resistance in mucosal bacteria from high Arctic migratory salmonids

“…Members of the salmonid family of teleost fish, Arctic char ( Salvelinus alpinus ) and lake whitefish ( Coregonus clupeaformis ), were sampled from the high Arctic. These fish spend summers feeding in the rich waters of the Arctic Ocean but must swim up rivers to inland lakes in order to escape sub‐zero temperatures during sea ice formation in the autumn, with these two related species migrating at the same time and on the same routes (Moore et al ., 2017 ; Hamilton et al ., 2019 ; Element et al ., 2020 ). Such migratory behaviour, known as anadromy, is a challenge to fish health with seasonal changes in salinity forcing osmoregulatory changes involving adaptations to the gills, alimentary tract, epithelium, and kidney function (McCormick, 2012 ; Kononova et al ., 2019 ).…”

“…Also critical during migration is the conservation of the fish immune system associated with the mucosal surfaces of the skin (Llewellyn et al ., 2014 ). This acts as the first line of defence against pathogens and is fortified with defence cells and antibacterial peptides, with the mucus also hosting commensal bacteria that show seasonal salinity‐associated turnover (Lokesh and Kiron, 2016 ; Hamilton et al ., 2019 ; Element et al ., 2020 ). These bacteria found in the mucus likely provide protection against pathogenic bacteria and the risk of dysbiosis in migrating salmonids.…”