Abstract. The Canadian Arctic Archipelago (CAA) acts as a watershed discharge in the Arctic Ocean, as it is characterized by advection from the Pacific and Atlantic waters, ice melt, local river discharge and net precipitation. Its waters are characterized by the mixing of Pacific and Atlantic water origin, and the meltwater supply originating from the Devon Ice Cap Glaciers and marine-terminating rivers. The Special Report on the Ocean and Cryosphere in a Changing Climate published by the IPCC in 2021, showed how the runoff into the Arctic Ocean increased for Eurasian and North American rivers by 3.3 ± 1.6 % and 2.0 ± 1.8 % respectively (1976–2017), hence, monitoring the freshwater supply within the CAA is crucial in a warming scenario. This paper aims to describe the water mass structures within the CAA, by analyzing physical and chemical tracers collected in 2019 during the Northwest Passage expedition held in July and August onboard the Swedish icebreaker Oden. The uniqueness of this study is the wide dataset composed of physical and chemical parameters (https://doi.org/10.18739/A2W66995R). Here, we implemented the Optimal Multiparameter analysis for the detection of the source water fractions, such as, Atlantic Water (AW), Pacific Water (PW), Meteoric Water (MW), and Sea Ice Meltwater (SIM). For this analysis, we used a nutrient ratio tracer defined Arctic Nitrate-Phosphate tracer, together with the absolute salinity and δ18O from the water samples. Our analysis confirmed the intrusion of the PW from the west in the upper layers and of AW from the east in the deeper layers. We also discriminated the meltwaters between glacial and sea ice origin and showed their spatial distribution in the study area. This study provides unique set of data from this under observed region and can serve as baseline for further analysis and continued data collection.

In late April 2011, photographs of an apparent male snow bunting (Plectrophenax nivalis) × Lapland longspur (Calcarius lapponicus) hybrid were taken at St. Lewis Inlet, Newfoundland and Labrador, Canada, while the bird was foraging in a mixed flock of both species along a previously documented spring migratory route. As far as we are aware, this is the first hybridization of these species documented anywhere in the world. The bird was identified as a male on the basis of longspur nape coloration, and it appears to have the head, beak, and back coloration and patterning of a Lapland longspur, but the chin, chest and throat, and overall appearance of a snow bunting. Although our research team has banded more than 50 000 birds of both species over the past 30 years across the latitudinal range of both species, we have never observed such a hybrid. While these Arctic-breeding species overlap spatially and temporally during wintering, migration, and breeding, longspurs and buntings have distinct sexual characters and breed in different ecological niches, which may account for the reproductive isolation or low rates of hybridization of these species. While we were unable to conduct detailed morphological or genetic comparisons on this particular individual for phylogenic interpretation, this report highlights the importance of reporting field observations that may indicate ecological changes affecting the hybridization rates of these inaccessible Arctic species.

No abstract