Grant: Discovery Launch Supplement

Nowhere on the planet is climate change occurring more intensely than in the Arctic, where rising temperatures and changing precipitation patterns are fundamentally transforming watersheds and coastal waters. Glacier melt and permafrost thaw are being compounded by temperature and precipitation extremes, resulting in wildfire and drought during some periods, but flooding in others, all of which have potentially dramatic consequences for the amount and quality of freshwater being transported to downstream aquatic systems. My research program aims to understand the drivers and impacts of climate change and other anthropogenic activities on aquatic ecosystem health and services from headwaters to the coastal ocean by combining hydrological, geochemical and biological tools and concepts. Although much effort has been focused on the main stems of the six largest rivers that discharge directly into Arctic marine waters, comparatively less is known about how changes in their headwaters are affecting water quality and biological productivity downstream. In the next five years, my research program will look to answer questions about the impacts of environmental change in the glacial headwater systems of the Yukon River, the fifth largest source of freshwater to Arctic marine waters. My research program has four specific objectives: 1.To evaluate the role of proglacial lakes in modifying snow and glacial meltwater biogeochemical exports to downstream rivers and lakes; 2.To determine the role of glacial meltwaters in supporting aquatic food webs using compound-specific stable isotopes; 3.To determine spatial variability in glacier influence on freshwater biogeochemistry over time; and, 4.To quantify fluxes of carbon, nutrients, trace metals and contaminants from glacial headwaters to the Yukon River. Water quantity will be evaluated using a combination of existing gauges and installation of gauges in key locations. Comprehensive field surveys of key water quality parameters, including carbon (inorganic and organic, dissolved and particulate), nitrogen, phosphorus, trace metals, and contaminants will be conducted throughout the year with more intensive sampling campaigns during the summer peak in glacial melt. Stable isotopes of water and carbon will be used to characterize different water sources and incorporated into Bayesian mixing models to estimate seasonal contributions of each water source. Laboratory analyses will primarily be conducted at the University of Ottawa's core facilities. Over 90% of Yukon residents live within the Yukon River watershed, such that changes in the alpine headwaters have potentially wide ranging impacts across northern Canada and further downstream in Alaska. At the local level, this work will inform land-use planning and climate change adaptation processes, with insights for both hydroelectric production and Pacific salmon conservation.