Environmental change in the Great Whale River region, Hudson Bay: Five decades of multidisciplinary research by Centre d'études nordiques (CEN)

Bhiry, Najat; Delwaide, Ann; Allard, Michel; Bégin, Yves; Filion, Louise; Lavoie, Martin; Nozais, Christian; Payette, Serge; Pienitz, Reinhard; Saulnier‐Talbot, Émilie; Vincent, Warwick F.

doi:10.2980/18-3-3469

Cited by 91 publications

(105 citation statements)

References 123 publications

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“…1) near the village of K-W, which lies in northern Quebec. This region has experienced rapid climate change, including an increase in mean annual temperatures from -4.2°C for 1932-1960 to -2.6 ± 1.2°C for the period 2001(Bhiry et al 2011). An additional 10 lakes in five other study sites were used for comparison purposes, including a rock-basin area unaffected by permafrost.…”

Section: Study Sitesmentioning

confidence: 99%

Oxygen depletion in subarctic peatland thaw lakes

et al. 2017

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Permafrost thawing and erosion results in the enrichment of northern lakes by soil organic matter. These allochthonous inputs favour bacterial decomposition and may cause the draw-down of dissolved oxygen to anoxic conditions that promote methanogenesis. Our objective in the present study was to determine the seasonal variations in dissolved oxygen in a set of permafrost peatland lakes in subarctic Quebec, Canada, and to relate these changes to metabolic rates, ice cover, and mixing. The lakes had high dissolved organic carbon concentrations, and their surface waters in summer had greenhouse gas concentrations that were up to one (CO 2 ) to three (CH 4 ) orders of magnitude above air-equilibrium values, indicating their strongly heterotrophic character. Consistent with these observations, the peatland lakes had elevated rates of bacterial production and oxygen consumption. Continuous measurements of oxygen by in situ sensors and of ice cover by automated field cameras showed that the lakes became fully anoxic shortly after freeze-up. The waters were partially reoxygenated by mixing events in spring and fall, but in one lake, the bottom waters remained anoxic throughout the year. These observations provide a foundation for subsequent biogeochemical and modelling studies of peatland thaw lakes as an abundant class of Arctic freshwater ecosystems.Key words: oxygen, permafrost, respiration, thaw lakes, thermokarst.Résumé : Le dégel et l'érosion du pergélisol entraînent l'enrichissement des lacs du Nord en raison de l'apport de matière organique de sol. Ces apports allochtones favorisent la décom-position bactérienne et peuvent causer la diminution d'oxygène dissous jusqu'à des conditions anoxiques qui aident la méthanogénèse. Notre objectif en entreprenant cette étude était de déterminer les variations saisonnières d'oxygène dissous pour un ensemble de lacs de tourbière de pergélisol dans la région subarctique du Québec, Canada, et d'établir un rapport entre ces changements et les taux métaboliques, la couverture de glace et le mélange. Les lacs avaient des concentrations élevées en carbone organique dissous et en été leurs eaux de surface avaient des concentrations en gaz à effet de serre qui étaient jusqu'à un (CO 2 ) et à trois (CH 4 ) ordres de grandeur au-dessus des valeurs d'équilibre d'air, indiquant leur caractère fortement hétérotrophe. Conformément à ces observations, les lacs de tourbière avaient des taux élevés de production bactérienne et de consommation d'oxygène. Des mesures prises en continue d'oxygène au moyen de capteurs in situ et de couverture de glace au moyen de caméras automatisées de terrain ont indiqué que les lacs devenaient entièrement anoxiques peu de temps après le gel. Les eaux ont été partiellement ré-oxygénées au printemps et à l'automne en raison de phénomènes de mélange, mais dans un des lacs, les

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Section: Study Sitesmentioning

confidence: 99%

Oxygen depletion in subarctic peatland thaw lakes

et al. 2017

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“…The ponds are surrounded by thick shrubs, sparse trees, and variable underlying peat (Bhiry et al 2011, Bouchard et al 2011. Bacteria in the ponds could originate from the surrounding soils, or be transported by wind or rain (Harding et al 2011).…”

Section: Origins Of Best Matchesmentioning

confidence: 99%

Distribution and identity of Bacteria in subarctic permafrost thaw ponds

Rossi¹,

Laurion²,

Lovejoy³

2013

Aquat. Microb. Ecol.

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Colored permafrost thaw ponds (thermokarst ponds), are abundant freshwater ecosystems in the subarctic. The ponds can emit significant levels of greenhouse gases, which are drivers of climate change, but little is known of their microbial communities. The ponds are vertically stratified for most of the year with suboxic to anoxic hypolimnia, suggesting varied habitats despite their shallow depths (1 to 4 m). Pelagic bacterial communities in 4 contrasting ponds near the coast of Hudson Bay, Quebec, Canada, were investigated by cloning and sequencing the 16S rRNA gene from environmental DNA. Surface and bottom water libraries yielded a total of 109 operational taxonomical units (defined as 97% sequence similarity) from 261 clones. The majority of clones had their closest matches to other environmental clones originating from freshwater environments, especially lakes. Proteobacteria accounted for the majority of sequences (33%), followed by Bacteroidetes (19%), Actinobacteria (13%), Chlorobi (10%), Verrucomicrobia (8%), and Cyanobacteria (7%). There were large differences in the assemblages inhabiting the different ponds and water layers. Bacteroidetes were predominant at the surface, while Chlorobi were found in bottom waters. Sequences with best matches to known methanotrophic bacteria represented up to 20% of all sequences. Methanotrophs included Methylobacter psychrophilus, Crenothrix polyspora, and Methylocystis parvus as closest matches. Ordination analysis clearly separated surface and bottom waters, where relatively large quantities of organic matter, low light availability, cool temperatures, and suboxic conditions selected for the distinct communities. The separation of surface waters of different ponds showed that bacterial communities could differ between superficially similar environments. This study illustrates the high diversity in bacterial assemblages occurring in ponds separated by a few meters, and thus, the potentially complex response of thaw pond systems to climate change.

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“…�ince these lakes were cored in the first year of the 21st century, there have been pronounced changes in climate in the region of Nunavik (northern Québec; Bhiry et al, 2011). Predictions by most models suggest that changes in this region in the near future (mid-21st century) will be felt mostly during the winter, with little change in summer temperatures.…”

Section: Discussionmentioning

confidence: 99%

“…Recent studies demonstrate that warmer temperatures have reached many parts of this vast region, notably on the eastern coast of Hudson Bay, where air temperatures have increased rapidly since the 1990s (Bhiry et al, 2011). These temperature changes, in turn, have led to important modifications of the landscape, including the appearance and development of numerous thermokarst thaw ponds (Bouchard et al, 2014) and the densification of the shrub cover (Ropars and Boudreau, 2012).…”

Section: Introductionmentioning

confidence: 99%

Response of Lacustrine Biota to Late Holocene Climate and Environmental Conditions in Northernmost Ungava (Canada)

Saulnier‐Talbot

Larocque‐Tobler²,

Gregory‐Eaves³

et al. 2015

ARCTIC

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ABSTRACT. Sediment cores from three lakes located in the northernmost region of Ungava, Québec (Canada) were examined to define aquatic community and ecosystem variability during the Late Holocene period. A chironomid-based transfer function was used to reconstruct August air temperature trends, and lacustrine primary production was inferred from sedimentary biogenic silica content and siliceous microfossil abundances. Trends in primary production, sediment organic matter content (estimated through loss on ignition), and chironomid-inferred temperature were compared to explore potential effects of environmental change on biotic assemblage composition at centennial to millennial time scales. Although no direct correlation between chironomid-inferred August air temperature and primary production was observed, we found indications that both chironomid and diatom communities were responding to the same overarching regional climatic and environmental processes. Over the last decade, northern Québec has been undergoing notable, rapid warming that contrasts with the relative inertia of the past few millennia. This study provides a baseline against which recent and future environmental changes in this region can be compared.Key words: chironomids; diatoms; biogenic silica; climate; northern lakes; Ungava RÉSUMÉ. Les archives sédimentaires couvrant la période de l'Holocène tardif ont été examinées dans trois lacs situés dans la région du nord de l'Ungava, au Québec (Canada). Un modèle d'inférence basé sur les assemblages de chironomides a été utilisé pour reconstruire la variabilité des températures de l'air du mois d'août, et la production primaire lacustre a été inférée par le contenu sédimentaire en silice biogénique et les abondances des microfossiles siliceux. Les variations historiques de la production primaire, du contenu organique du sédiment (évalué par la perte au feu) et les températures inférées ont été comparées afin d'explorer les effets potentiels des changements environnementaux sur la composition des assemblages à différentes échelles temporelles (centenaires à millénaires). Malgré le fait qu'aucune corrélation directe n'ait été observée entre les températures inférées en août et la productivité primaire, certaines indications suggèrent que les communautés de chironomides et de diatomées répondaient aux mêmes processus climatiques et environnementaux régionaux. Au cours de la dernière décennie, le nord du Québec a connu un réchauffement rapide et marqué, contrastant avec l'inertie relative des derniers millénaires. Cette étude fournit le scénario de référence par rapport auquel les changements environnementaux actuels et futurs pourront être comparés dans cette région.

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Environmental change in the Great Whale River region, Hudson Bay: Five decades of multidisciplinary research by Centre d'études nordiques (CEN)

Cited by 91 publications

References 123 publications

Oxygen depletion in subarctic peatland thaw lakes

Oxygen depletion in subarctic peatland thaw lakes

Distribution and identity of Bacteria in subarctic permafrost thaw ponds

Response of Lacustrine Biota to Late Holocene Climate and Environmental Conditions in Northernmost Ungava (Canada)

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