Sentinelle Nord

Climate-driven alterations of the marine environment are most rapid in Arctic and subarctic regions, including Hudson Bay in northern Canada, where declining sea ice, warming surface waters and ocean acidification are occurring at alarming rates. These changes are altering primary production patterns that will ultimately cascade up through the food web. Here, we investigated (i) the vertical trophic structure of the Southampton Island marine ecosystem in northern Hudson Bay, (ii) the contribution of benthic and pelagic-derived prey to the higher trophic level species, and (iii) the relative contribution of ice algae and phytoplankton derived carbon in sustaining this ecosystem. For this purpose, we measured bulk stable carbon, nitrogen and sulfur isotope ratios as well as highly branched isoprenoids in samples belonging to 149 taxa, including invertebrates, fishes, seabirds and marine mammals. We found that the benthic invertebrates occupied 4 trophic levels and that the overall trophic system went up to an average trophic position of 4.8. The average δ34S signature of pelagic organisms indicated that they exploit both benthic and pelagic food sources, suggesting there are many interconnections between these compartments in this coastal area. The relatively high sympagic carbon dependence of Arctic marine mammals (53.3 ± 22.2 %) through their consumption of benthic invertebrate prey, confirms the important role of the benthic subweb for sustaining higher trophic level consumers in the coastal pelagic environment. Therefore, a potential decrease in the productivity of ice algae could lead to a profound alteration of the benthic food web and a cascading effect on this Arctic ecosystem.

The phosphonate herbicide glyphosate, which is the active ingredient in the commercial formulation Roundup®, is currently the most globally used herbicide. In aquatic ecosystems, periphytic biofilms, or periphyton, are at the base of food webs and are often the first communities to be in direct contact with runoff. Microcosm experiments were conducted to assess the effects of a pulse exposure of glyphosate on community composition and chlorophyll a concentrations of lake biofilms at different colonization stages (2 months, 1 year, and 20 years). This is the first study that uses such contrasting submersion periods. Biofilms were exposed to either environmental levels of pure analytical grade glyphosate (6 μg/L, 65 μg/L, and 600 μg/L) or to corresponding phosphorus concentrations. Community composition was determined by deep sequencing of the 18S and 16S rRNA genes to target eukaryotes and cyanobacteria, respectively. The results showed that submersion period was the only significant contributor to community structure. However, at the taxon level, the potentially toxic genus Anabaena was found to increase in relative abundance. We also observed that glyphosate releases phosphorus into the surrounding water, but not in a bioavailable form. The results of this study indicate that environmental concentrations of glyphosate do not seem to impact the community composition or metabolism of lake biofilms under pulse event conditions.

The marine pelagic compartment spans numerous trophic levels and consists of numerous reticulate connections between species from primary producers to iconic apex predators, while the benthic compartment is perceived to be simpler in structure and comprised of only low trophic level species. Here, we challenge this paradigm by illustrating that the benthic compartment is home to a subweb of similar structure and complexity to that of the pelagic realm, including the benthic equivalent to iconic polar bears: megafaunal-predatory sea stars.

Climate warming at high latitudes has contributed to the growing interest in shrub tree-ring analysis. Shrub architecture presents new challenges for dendrochronology, such as the seemingly lower and inconsistent climatic sensitivity of stems vs. root collars. Shrub stems may thus be considered as sub-optimal to study climate–growth relationships. In this paper, we propose that the lower climatic sensitivity of stems could be caused by the use of unsuitable detrending methods for chronologies spanning decades rather than centuries. We hypothesize that the conversion of the ring width (RW) to basal area increment (BAI) is better suited than traditional detrending methods to removing age/size-related trends without removing multi-decadal climate signals. Using stem and root collar samples collected from three sites in the forest–tundra ecotone of eastern Canada, we compared the climate–growth relationships of these two approaches for stems and root collars using mixed-effects models. The climate sensitivity was, on average, 4.9 and 2.7 times higher with BAI than with detrended (mean-centered) RW chronologies for stems and root collars, respectively. The climatic drivers of radial growth were identical for stems and root collars when using BAI (July temperature and March precipitation), but were inconsistent when using detrended RW series (root collars: July temperature and March precipitation at all sites; stems: April and June temperature, depending on the site). Although the use of BAI showed promising results for studying long-term climate signals in shrub growth chronologies, further studies focusing on different species and locations are needed before the use of BAI can become broadly used in shrub dendrochronology.

Seasonal migrants transport energy, nutrients, contaminants, parasites and diseases, while also connecting distant food webs between communities and ecosystems, which contributes to structuring meta-communities and meta-ecosystems. However, we currently lack a framework to characterize the structure of the spatial connections maintained by all migratory species reproducing or wintering in a given community. Here, we use a network approach to represent and characterize migratory pathways at the community level and provide an empirical description of this pattern from a High-Arctic terrestrial community. We define community migration networks as multipartite networks representing different biogeographic regions connected with a focal community through the seasonal movements of its migratory species. We focus on the Bylot Island High-Arctic terrestrial community, a summer breeding ground for several migratory species. We define the non-breeding range of each species using tracking devices, or range maps refined by flyways and habitat types. We show that the migratory species breeding on Bylot Island are found across hundreds of ecoregions on several continents during the non-breeding period and present a low spatial overlap. The migratory species are divided into groups associated with different sets of ecoregions. The non-random structure observed in our empirical community migration network suggests evolutionary and geographic constraints as well as ecological factors act to shape migrations at the community level. Overall, our study provides a simple and generalizable framework as a starting point to better integrate migrations at the community level. Our framework is a far-reaching tool that could be adapted to address the seasonal transport of energy, contaminants, parasites and diseases in ecosystems, as well as trophic interactions in communities with migratory species.

Seasonally abundant arthropods are a crucial food source for many migratory birds that breed in the Arctic. In cold environments, the growth and emergence of arthropods are particularly tied to temperature. Thus, the phenology of arthropods is anticipated to undergo a rapid change in response to a warming climate, potentially leading to a trophic mismatch between migratory insectivorous birds and their prey. Using data from 19 sites spanning a wide temperature gradient from the Subarctic to the High Arctic, we investigated the effects of temperature on the phenology and biomass of arthropods available to shorebirds during their short breeding season at high latitudes. We hypothesized that prolonged exposure to warmer summer temperatures would generate earlier peaks in arthropod biomass, as well as higher peak and seasonal biomass. Across the temperature gradient encompassed by our study sites (>10°C in average summer temperatures), we found a 3-day shift in average peak date for every increment of 80 cumulative thawing degree-days. Interestingly, we found a linear relationship between temperature and arthropod biomass only below temperature thresholds. Higher temperatures were associated with higher peak and seasonal biomass below 106 and 177 cumulative thawing degree-days, respectively, between June 5 and July 15. Beyond these thresholds, no relationship was observed between temperature and arthropod biomass. Our results suggest that prolonged exposure to elevated temperatures can positively influence prey availability for some arctic birds. This positive effect could, in part, stem from changes in arthropod assemblages and may reduce the risk of trophic mismatch.

This paper presents the EcoChip 2, an autonomous multimodal bio-environmental sensor platform for the monitoring of microorganisms in the northern habitat. The EcoChip 2 prototype includes an array of 96-wells for the continuous monitoring of microbiological growth through a multichannel electrochemical impedance analyzer circuit. In addition, the platform includes luminosity, humidity, temperature sensors and monitoring. The developed electronic board uses an ultra-low-power microcontroller unit, a custom power management unit, a low-power wireless ISM-2.45 GHz transceiver, and a flash memory to accumulate and store the sensor data over extended monitoring periods. When a wireless base station is placed within the transmission range of the EcoChip 2, an embedded low-power wireless transceiver transmits the 96-wells impedance data and the other sensor data stored in the flash memory to the user interface. We present the measured performance of the prototype, along with laboratory test results of bacterial growth measurements inside the 96 wells in parallel. We show that the EcoChip 2 can successfully measure the impedances associated with bacterial growth over several hours using an excitation frequency of 2 kHz with power consumption of 114.6 mW under operating mode.

Abstract Horizontal Gene Transfer, the process by which bacteria acquire new genes and functions from non-parental sources, is common in the human microbiome 1,2 . If the timescale of HGT is rapid compared to the timescale of human colonization, then it could have the effect of ‘personalizing’ bacterial genomes by providing incoming strains with the genes necessary to adapt to the diet or lifestyle of a new host. The extent to which HGT occurs on the timescale of human colonization, however, remains unclear. Here, we analyzed 6,188 newly isolated and sequenced gut bacteria from 34 individuals in 9 human populations, and show that HGT is more common among bacteria isolated from the same human host, indicating that the timescale of transfer is short compared to the timescale of human colonization. Comparing across 9 human populations reveals that high rates of transfer may be a recent development in human history linked to industrialization and urbanization. In addition, we find that the genes involved in transfer reflect the lifestyle of the human hosts, with elevated transfer of carbohydrate metabolism genes in hunter gatherer populations, and transfer of antibiotic resistance genes among pastoralists who live in close contact with livestock. These results suggest that host-associated bacterial genomes are not static within individuals, but continuously acquire new functionality based on host diet and lifestyle.

Habitat degradation and fragmentation reduce habitat structural complexity (e.g. amount of physical features) and increase habitat edges. While many studies have focused on the effects of habitat edges or complexity on biodiversity, relatively few have disentangled them or investigated their effects over time. We investigated how proximity to the edge of eelgrassZosterasubg.Zostera marinaLinnaeus, 1753 habitat, shoot density and their interactions across seasons can influence the diversity pattern of epifaunal assemblages in meadows situated in a Mediterranean lagoon (France). We used a combination of field sampling andin situmanipulations with artificial seagrass units (ASUs) mimicking low and high shoot densities. During autumn and spring, we found that shoot density, Z. marina biomass and leaf area index (LAI) were higher inside the meadows than at the edge, while epiphyte load was the highest in spring at the edges. Epifaunal abundance and diversity were higher at the edge than inside the meadow for both natural shoots—regardless of the epiphyte load—and ASUs in spring. In autumn, epifaunal abundance varied positively with ASU density, regardless of the position in the meadow. Our results also showed that edges and habitat complexity affect the epifaunal structure differently across seasons. Therefore, we suggest that recruitment of macrofauna is the main mechanism explaining a positive edge effect during spring. This work highlights the need to consider seasonal dynamics in the assessment of habitat fragmentation and degradation.

The COVID-19 pandemic has raised many concerns among Indigenous communities about virus transmission risks from wild food, particularly migratory birds. Snow geese contribute significantly to food security in Indigenous contexts, which is precarious in many communities. The risk to goose hunters is very unlikely as coronaviruses found in birds are from different genera than that of SARS-CoV-2, the etiologic agent responsible for COVID-19. Nevertheless, little is currently known about the host tropism range of SARS-CoV-2. To address the concerns raised by Northern communities, we captured 500 snow geese in May 2020 at their stopover along the St Lawrence estuary. We took oropharyngeal and cloacal samples before releasing the birds. All samples were tested for SARS-CoV-2 within one week and were found to be PCR-negative, allowing us to communicate rapidly with Northern communities. The current pandemic has shown that the importance of understanding animals as potential viral reservoirs, and that a better understanding of these viruses will better prepare us for future spillover events. This project demonstrates that researchers can be quickly and efficiently mobilized to respond to concerns from Indigenous communities.

Abstract Arctic ecosystems present unique opportunities for community‐wide monitoring, in part due to their relatively low species richness. However, conducting research in these remote environments poses significant logistical challenges, resulting in long‐term monitoring being exceedingly rare. Here, we focus on the long‐term, intensive ecological monitoring efforts conducted on the south plain of Bylot Island (~400 km 2 , Nunavut, Canada), which has generated a remarkable dataset spanning up to 30 years, a rarity in tundra ecosystems. Our goals are to (1) provide long‐term time‐series of annual vertebrate density measured at various spatial scales and for the broadest possible range of species and years, to allow the assessment of interannual variability and trends in species density; and (2) upscale annual vertebrate abundance or sometimes long‐term averages to the landscape scale (400 km 2 ) to allow food web modeling. Monitoring data include intensive capture–mark–recapture density estimates of lemmings on trapping grids, systematic or opportunistic nest monitoring conducted across the entire study area or within specific plots for all bird species, transects of vertebrate counts distributed throughout the study area, daily incidental observations of vertebrates, and satellite tracking of foxes. We standardized data obtained with different field methods to provide a readily usable dataset for community ecologists. Long‐term time‐series of vertebrate densities span 3–27 years, with a median of 16.5 years for 22 species. We estimated landscape‐scale abundance for all 35 species of the community based on annual time‐series for 15 of them and average abundance for the remaining 20 species. Furthermore, we provide body mass data for each species, based on empirical onsite measurements for 18 species and from the literature for the remaining species. Body mass is essential to convert species abundance into biomass for studies of trophic fluxes and ecosystem processes. Daily climatic data recorded since 1992 from weather stations within the study area are also available and complement the vertebrate dataset. The ecological data presented offer a rare opportunity for holistic empirical studies of community structure and dynamics. Considering that the study site is a pristine and protected area that has experienced minimal direct anthropogenic impact, it also provides an ideal baseline for investigating the impacts of global changes on high‐latitude terrestrial ecosystems. There are no copyright restrictions on the data or code, and this data paper should be cited when these items are reused.

Colitis is associated with endocannabinoidome (eCBome) and gut microbiome alterations, both of which are influenced by the diet, and thus may be modulated through nutritional components as potential therapeutic targets for colitis. We assessed the effects of n-3 polyunsaturated fatty acid (PUFA)-rich fish (FO) and seal (SO) oils in the dextran sodium sulphate (DSS) colitis mouse model. Mice were assessed for effects on inflammation, intestinal permeability, anxiety-like behaviour, gut microbiota composition and colon, blood and brain eCBome mediator levels. While neither FO or SO counteracted DSS-induced loss of weight, SO mitigated the increase in intestinal permeability and was more efficacious at reducing inflammation markers (Il1b, Il6, Tnfa and Arg1) than FO. DSS-induced changes in the bacterial community were not altered by FO or SO, which however mitigated alterations in the abundance of the Family XII UCG01 genera. DSS altered several eCBome and oxylipin bioactive lipid levels in a tissue-specific manner. FO and/or SO counteracted some of these changes, especially by increasing the levels of those lipids derived from n-3 PUFAs, many of which have anti-inflammatory activities. Interestingly, the novel eicosapentaenoic acid-derived eCBome mediator 2-eicosapentaenoyl glycerol was a top defining lipid of both FO and SO groups in all tissues. These data point to FO and, particularly SO, as potentially beneficial treatments of colitis through alterations in the eCBome, which is dysregulated in colitis.

Circadian disruption is a pervasive environmental stressor associated with increased risk of metabolic and inflammatory disease, yet sex-specific physiological responses remain poorly defined. Here, we investigated how constant light (LL) exposure, used as a circadian stressor, is associated with changes in the fecal microbiome and short-chain fatty acids (SCFAs), tissue-specific bioactive lipid mediator and systemic cytokine levels in female and male mice. Mice were kept under standard light/dark (LD; 12 : 12) or LL (24 : 0) conditions for 10 days before feces collection and for 5 more days before tissue collection. Females exhibited broader microbiota restructuring along with decreases in oxylipins within the jejunum. In the brain pronounced increases of N-acylethanolamine levels in the cerebellum and hypothalamus were observed when male and female mice were analyzed together, though these changes were largely driven by increased levels in the hypothalamus of females. Changes in muscle lipids were associated with the predominant muscle fiber type, with the soleus showing increases in a broad variety of lipid classes in both females and males. Adipose tissues also showed divergent responses to LL, with subcutaneous white adipose tissue having significantly decreased oxylipin levels specifically in males. Within plasma, females generally showed a more inflammatory profile than males. Together, these findings suggest that sex strongly shapes microbial, lipidomic, and immune pathways changes under circadian stress, highlighting divergent physiological strategies in response to light-cycle perturbation, which may contribute to sex-specific vulnerability at the level of metabolic and inflammatory dysregulation.

Abstract Predator–prey interactions are a fundamental aspect of ecology that has generated sustained research interests. Progress in the field stems from a diverse range of approaches, from highly controlled yet simplified mathematical and agent‐based models, to grounded but data‐limited field studies. As a compromise between mathematical and observation‐oriented methods, we introduce an original approach based on an outdoor game. In this game, biologged human players follow simple rules to impersonate predators and prey in a natural landscape augmented with synthetic resource patches and refuges. We investigated the behaviour, movement, functional response and spatial organization of over 25 players simultaneously monitored during nine simulations to determine whether the game could replicate realistic predator–prey dynamics. Results derived from our real‐life simulations were consistent with ecological patterns expected in natural systems. We found that (a) predator and prey movements were driven by risk and reward trade‐offs, (b) predators took advantage of linear features to travel at higher speed, making these areas risky for prey, (c) prey had nonlinear and risk‐sensitive functional responses and (d) consumer–resource interactions were spatially modular and defined by players' movement rates and landscape features. Moreover, the comprehensive dataset generated through the game allowed for the exploration of phenomena that are challenging to study in natural settings, such as spatial memory and the influence of satiety on resource acquisition rates. The approach offers a simple, computationally accessible and genuinely amusing way to explore the complex ramifications of predator–prey interactions and test otherwise data‐deficient hypotheses. The strength and originality of the method lies in the use of living agents—players—making decisions in a real‐world setting. This aspect alleviates the computational and empirical burden of defining and estimating decision‐related parameters needed to build simulators, while generating extensive datasets in a flexible experimental framework that is generally out of reach for empirical studies. It also offers immersive insights into predator–prey interactions, making it an engaging pedagogical tool that encourages creative thinking. The numerous possible scenarios that can be explored are only constrained by the investigator's creativity in adapting game rules and the players' desire to win.

ABSTRACT Aim Seasonally migratory species generate large movements of organisms and biomass between distant breeding and non‐breeding grounds. However, our understanding of how migratory species shape global networks of interconnected communities (meta‐communities) remains limited. Migratory links between communities can be measured in different ways (e.g., species occurrence, abundance or biomass), each providing complementary information by modulating the relative importance of species in meta‐communities. We aim at investigating to what extent measuring migratory links using species occurrence, abundance or biomass can reveal alternative structures (i.e., topology) in a meta‐community linking an Arctic breeding ground to remote non‐breeding grounds. Location We use as a study case the High‐Arctic vertebrate community of Bylot Island (Nunavut, Canada), along with ecoregions of North and South America, Europe and Africa. Time Period Present. Major Taxa Studied Terrestrial Arctic birds (30 species) and mammals (5 species). Methods We first consider species occurrence at the non‐breeding grounds to define migratory links within the meta‐community. Secondly, we measure the number of individuals and the amount of biomass travelling along those links. Finally, we compare the meta‐community structure under each scenario using a migration network representation. Results Patterns of species occurrence, abundance and biomass reveal that temperate ecoregions of South and especially North America maintain strong ecological connections with the vertebrate community of Bylot Island. However, the structural role of species within the network can vary substantially depending on how migratory links are measured (i.e., contrasting topological anomalies). Using abundance or biomass to measure migratory links results in a finer partitioning of the network into modules compared to using species occurrence alone. Main Conclusions We highlight that using different metrics of migratory links reveals unique, yet complementary structural features of meta‐communities. These findings contribute to assessing the vulnerability of communities to perturbations occurring in distant but connected environments through migration.

The literature on how Inuit women relate to justice has thus far portrayed them largely as victims of various types of violence and in need of assistance. However, justice does not concern them only as victims, offenders, or affected family members, as many of them work in this field as crucial actors for their communities, providing people in difficulty with support and helping them navigate a complex structure. This article emphasizes the important role of Nunavik Inuit women today in maintaining community harmony. We also explore their views on the justice system and outline what an Inuit system of justice could look like today. Our research project used a participatory methodology, an ontological approach, and both qualitative and quantitative methods. Our results suggest that Nunavik justice is not simply a legal institution and should therefore be defined much more broadly and incorporate the moral principles of social responsibility and interdependence.

Background: Studying the anti-predatory behavior of mammals represents an important challenge, especially for fossorial small mammals that hide in burrows. In the Arctic, such behaviors are critical to the survival of lemmings considering that predation risks are high every summer. Because detailed information about how lemmings use burrows as hideouts is still lacking, we developed a 1.59 g photosensitive collar to record any event of a small mammal moving between a dark area (e.g., burrow) and a bright area (e.g., outside the burrow). Tests of how collars affected lemming behavior were conducted in captivity in Cambridge Bay, Nunavut, Canada, in November 2019 and field tests were conducted on Bylot Island, Nunavut, Canada, in August 2021. Results: The device was made of two chemical batteries and a printed circuit board (PCB) equipped with a photosensor and a real-time clock that recorded amplitude transient thresholds of light (lux) continuously. In accordance with ethical use of such devices, we verified that no abnormal loss of body mass was observed in captive or free-ranging lemmings, and no difference in recapture rates were observed between those with and without a collar, though we could not test this for periods longer than 108 h. Measurements of light intensities revealed consistent patterns with high lux levels at mid-day and lowest during the night. Lemmings showed clearly defined behavioral patterns alternating between periods outside and inside burrows. Despite 24-h daylight in the middle of the summer, August nighttime (i.e., 11 PM to 4 AM) lux levels were insufficient for amplitude transient thresholds to be reached. Conclusion: By taking advantage of the long periods of daylight in the Arctic, such technology is very promising as it sets new bases for passive recording of behavioral parameters and builds on the prospect of further miniaturization of batteries and PCBs.

Animal models fed a high-fat high-sucrose (HFHS) diet are commonly used to study obesity and cardiometabolic diseases. While much attention is paid to the impact of fat and carbohydrates sources, very little consideration is given to the composition of dietary proteins. Indeed, casein is often the only source of protein in rodent’s diet. This study aimed to evaluate the impact of a dietary protein mix that is more relevant to typical intakes of proteins in humans and its influences on body weight gain, metabolic health and gut microbiota. Our new diet contained a mix of 10 protein sources based on NHANES data that were incorporated into low-fat low-sucrose (LFLS) and HFHS diets. C57BL/6J mice were fed these diets or control diets containing identical amounts of casein as the only source of protein for 12 weeks. Feces were collected for gut microbiota investigation, an oral glucose tolerance test was performed and tissues were harvested for analysis of insulin signaling and mTOR/S6K1 activation. 16S rRNA gene sequencing of fecal samples showed that both LFLS and HFHS mice fed the protein mix had increased gut microbiota diversity, and significant changes in the relative abundance of several bacterial species (higher Adlercreutzia or Tyzzerella, lower Bacteroides or Akkermansia) as compared to mice fed casein only. Importantly, inclusion of the protein mix amplified the effects of the HFHS diet on the development of obesity, glucose intolerance and hyperinsulinemia as compared to casein-fed animals, whereas no difference was observed in the context of LFLS feeding. Evaluation of insulin signaling in the liver also revealed that the protein mix potentiated the effect of HFHS feeding on the mTORC1/S6K1 pathway, increasing inhibitory phosphorylation of IRS-1 on Ser1101 and leading to further impairment of Akt activation by insulin. Our results reveal that compared to pure casein, feeding a protein mixture causes major changes in the gut microbiota profile and greater impact on HFHS-induced obesity and associated metabolic impairments. This study illustrates the importance of considering a diverse source of dietary proteins when using laboratory animal models to more reliably reproduce the development of metabolic syndrome in humans, and to enhance the clinical relevance of nutritional and therapeutic interventions. N/A.

Abstract Armand Tagoona (1926–1991) was born in Naujaat (Repulse Bay, Northwest Territories) in 1926, from an Inuk mother and a German father. Born as a Roman Catholic, he converted to Anglicanism. In 1969, he founded a new independent religious group affiliated to the Anglican Church in Qamani’tuaq (Baker Lake, Northwest Territories): the Arctic Christian Fellowship (ACF). In this paper, we examine his life briefly as well as this very first “Inuit church” he created. We argue that Tagoona played the role of a mediator encompassing various religious traditions and various cultures at a time when solid boundaries separated all these institutions. In bridging them, Tagoona’s church turned to be very innovative and aimed at more religious autonomy, while being fundamentally guided by the words of God. Tagoona’s church carries conversionist, reformist and utopian aspects at the same time.

Scottie, Joan, Warren Bernauer et Jack Hicks, 2022. I will Live for Both of Us. A History of Colonialism, Uranium Mining, and Inuit Resistance. Winnipeg, University of Manitoba Press.. Un article de la revue Études Inuit Studies (Voix Inuit : Archéologie communautaire dans l’Arctique nord-américain) diffusée par la plateforme Érudit.