Atlantic salmon become thermally stressed when water temperatures exceed 23°C. To alleviate this stress, they behaviourally thermoregulate by moving to patches of cold water, often forming large aggregations. These patches are known as thermal refuges. Given the consensus that climate change will increase temperatures in Atlantic salmon catchments, thermal refuges will become increasingly important in minimising summer mortalities. While the behaviour of salmonids within thermal refuges is fairly well understood, less is known about their main stem movement in search of thermal refuges or its thermal and temporal cues. We detail the results of a PIT telemetry study to investigate the main stem movement behaviour of thermally stressed Atlantic salmon parr in a temperature-impacted river. PIT antennas placed around two thermal refuges and at the upstream and downstream limits of their surrounding reach were used to record the movement of salmonids during a heatwave. We observed parr movement at the upstream and downstream antennas 135 min prior to the occurrence of the midpoint of aggregations in the thermal refuges, indicating that Atlantic salmon parr make reach-scale movements in search of cool water prior to aggregating. Logistic regression showed that the number of degree hours >28°C predicted the occurrence of main stem movement with a good degree of accuracy, indicating that this temperature represents a fundamental threshold causing Atlantic salmon parr to move towards cool water. Such data could be instrumental in allowing river managers to place limits on human activity within rivers, allowing salmon populations time to recover following heat stress events.

Canada's North is experiencing a growing interest in community-based environmental monitoring (CBEM) as resource exploitation and climate change increasingly impact these remote territories, and as recognition of the value and relevance of indigenous knowledge increases. IMALIRIJIIT, a CBEM program involving Science Land Camps, capacity-building workshops and scientific data collection with the participation of youth, Elders, local experts and researchers was co-initiated by the Inuit community of Kangiqsualujjuaq in Nunavik (Quebec) and university-affiliated researchers. This hands-on and land-based program aims to establish a sustainable environmental monitoring program of the George River, before the start of operations of a rare earth elements (REEs) mining project in its upper watershed. The community wanted its own independent and long-term environmental monitoring program to collect baseline data and promote local capacitybuilding. IMALIRIJIIT program includes water quality measurements, biomonitoring for contaminant and REEs analysis in traditional foods, remote sensing analysis of water quality parameters and vegetation change at the watershed scale as well as interactive mapping of traditional ecological knowledge related to the George River. The outcomes and challenges of the IMALIRIJIIT Program are discussed in order to identify the conditions for the successful implementation of CBEM and environmental stewardship in the George River watershed, Nunavik.

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To advance our understanding of permafrost hillslope drainage dynamics and its influence on streamflow hydrochemistry, we instrumented a hillslope-stream sequence located in the headwaters of the Niaqunguk River watershed, Nunavut, Canada (63°N, 68°W). We combined high spatial resolution field measurements of water and frost tables across the hillslope, with semiweekly measurements of groundwater and streamflow chemistry to track the evolution of streamflow chemistry during active layer thaw. Interestingly, localized differential thaw patterns emerged under near saturation conditions across the instrumented hillslope, the result of a low-frequency high-magnitude summer rainfall event. Hillslope structure and uneven active layer thaw created two distinct fill-and-spill domains. A subsurface domain defined by frost table microtopography and a surface domain defined by surface topography. We observed a seasonal shift in streamflow chemistry with an increased influence of water flowing through the underlying mineral soils as the active layer thawed. As thaw progressed streamflow chemistry began to match that of the riparian groundwater, which was a mixture of hillslope surface and subsurface water. Hillslope-stream surface connections were sporadic and occurred when rainfall and saturation conditions across the lower portion of the hillslope were sufficient for water to spill out of midslope surface depressions and across a saturated riparian zone and into the stream. This research shows how hillslope structure and thaw processes influence hillslope-stream connectivity in permafrost terrain.