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Shorthorn sculpin (Myoxocephalus scorpius) are among the most numerous consumers in the Arctic nearshore marine habitats. Despite this, little is known about their movement ecology or predator-prey interactions, particularly with Arctic cod (Boreogadus saida), an important forage fish in the Arctic. Using acoustic telemetry, the movements of tagged sculpin and cod were quantified based on specific locations using a Vemco positioning system during open water when both species were present in the near shore. Movement trajectories of sculpin distinguish three unique types: foraging and feeding behaviour and large transiting movements. The relative time of each of these movement types were correlated to biotic (presence of large numbers of acoustically tagged Arctic cod) and abiotic factors (percent ice coverage and temperature). This study provides unique data on the movement, feeding ecology, and behaviour of an abundant Arctic benthic fish that demonstrates similar movement types to temperate fish. However, further study is needed to quantify specifically the trophic interactions of these important fish and impact on food webs in the rapidly changing Arctic. Meme si les chaboisseaux a epines courtes (Myoxocephalus scorpius) figurent parmi les consommateurs les plus nombreux dans les habitats marins littoraux de l'Arctique, les connaissances sur l'ecologie de leurs deplacements et leurs interactions predateurs-proies, particulierement avec la morue polaire (Boreogadus saida), un important poisson-proie dans l'Arctique, sont limitees. En utilisant la telemetrie acoustique, nous avons quantifie, sur la base d'emplacements precis, les deplacements de chaboisseaux et de morues etiquetes a l'aide d'un systeme de positionnement Vemco en periode d'eau libre, quand les deux especes etaient presentes pres des cotes. Les trajectoires de deplacement des chaboisseaux permettent de distinguer trois types de deplacements, soit des deplacements associes au comportement d'approvisionnement et d'alimentation et de grands deplacements de transit. Le moment relatif de chacun de ces types de deplacements a ete correle a des facteurs biotiques (presence d'un grand nombre de morues polaires dotees d'etiquettes acoustiques) et abiotiques (pour cent de couverture de glace et temperature). L'etude fournit des donnees singulieres sur les deplacements, l'ecologie de l'alimentation et le comportement d'un poisson benthique arctique abondant qui presente des types de deplacements semblables a ceux de poissons d'eaux temperees. D'autres travaux sont toutefois necessaires pour quantifier plus particulierement les interactions trophiques de cet important poisson et leur incidence sur les reseaux trophiques dans un milieu arctique en evolution rapide., Introduction The marine ecosystems of the High Arctic are dynamic, with large seasonal changes in light and temperature, which in turn influence the growth and abundance of primary producers (Walsh [...]

Polyploidy among plants is most frequent in the arctic, where glaciation cycles put selective pressures on populations by repeated fragmentation and fluctuation in climate. Polyploids should have been more fit in the novel habitats created as glaciers receded because of increased genetic material and novel gene products, which results in phenotypic plasticity and rapid adaptation. Higher ploidy is then expected to confer a broader tolerance of environmental conditions. Eutrema edwardsii R. Br. (Brassicaceae) is an arctic-alpine mustard with a near circumpolar distribution that occurs as a tetraploid, hexaploid, and octaploid. We used flow cytometry to document the distribution of polyploid cytotypes using herbarium tissue, and modeled the niche of each cytotype to test for niche differentiation. Flow cytometry revealed four cytotypes among 85 individuals. Notably, 60% of the herbarium tissue assays were successful using tissue up to 50 years old. Principle components analysis was performed on 20 climatic variables, of which, the first four axes were used as environmental variables for niche modeling. Niche models were created for tetraploid and hexaploid populations and used to calculate niche overlap (Shoener's D). Overlap between tetraploid and hexaploid models (D = 0.534) is lower than the null distribution (D = 0.681-0.944) supporting the hypothesis of niche divergence.Key words: allopolyploidy, flow cytometry, Maxent, cryptic variation, herbarium tissue.La polyploidie chez les plantes est plus frequente dans l'Arctique ou les cycles de glaciation exercent des pressions selectives sur les populations par des fragmentations et des fluctuations repetees sur le climat. Les individus polyploides devraient etre mieux adaptes aux nouveaux habitats lors de la recession des glaciers a cause d'un materiel genetique plus riche et de produits genetiques nouveaux, ce qui donne lieu a une plasticite phenotypique et une adaptation rapide. Une ploidie plus elevee est ainsi presumee conferer une tolerance plus etendue aux conditions environnementales. Eutrema edwardsii R. Br. (Brassicaceae) est une moutarde alpine arctique dont la distribution se situe pres du circumpolaire, qui se presente sous formes tetraploide, hexaploide et octaploide. Les auteurs ont utilise la cytometrie en flux pour documenter la distribution des cytotypes polyploides a partirde tissu d'herbier etils ont modelise laniche de chaque cytotype afin de tester la differenciation des niches. La cytometrie en flux a revele l'existence de quatre cytotypes parmi les 85 individus. Fait notable, 60 % des tests realises avec les tissus d'herbier etaient fructueux, meme sur des tissus ayant jusqu'a 50 ans d'age. L'analyse en composantes principales a ete realisee sur 20 variables climatiques, parmi lesquelles les quatre premiers axes ont ete utilises comme variables environnementales pour la modelisation de la niche. Des modeles de niche ont ete crees pour les populations tetraploides et hexaploides et utilises pour calculer le chevauchement des niches (indice D de Shoener). Le chevauchement entre les modeles tetraploides et hexaploides (D = 0,534) est plus faible que la distribution nulle (D = 0,681-0,944), appuyant l'hypothese de divergence des niches. [Traduit par la Redaction]Mots-cles : alloploidie, cytometrie en flux, Maxent, variation cryptique, tissu d'herbier., IntroductionPolyploidy is ubiquitous among vascular plants and is especially prevalent in the arctic where it characterizes up to 80% of plant species (Soltis and Soltis 2000; Abbott and Brochmann 2003), [...]

INTRODUCTION GLOBAL MARINE ECOSYSTEMS ARE FACING numerous stressors, including the opening of new shipping pathways, invasive species, and climate change. In the Arctic Ocean, the ongoing loss of sea ice [...]

INTRODUCTION THE ARCTIC IS WARMING AT TWICE THE AVERAGE global rate and mean summer temperature has increased significantly in more than 50% of the region (Serreze et al., 2000; Xu [...]

Abstract: Different components of global change (e.g., climate change, land use, pollution, and introduced species) continue to alter biodiversity worldwide. As northern regions are still relatively undisturbed and will likely [...]

The Arctic, located directly between the United States and the Soviet Union, was on the front lines of the Cold War. Nuclear submarines prowled the Arctic Ocean while long-range bombers [...]