Grant: Discovery Grants Program - Individual

Inland water ecosystems are inextricably linked to their surrounding watersheds. A large fraction of the organic matter (OM) and microbes circulating within northern aquatic networks originates within the surrounding terrestrial ecosystems, and enter inland waters via lateral water transport. These terrestrial inputs strongly shape the metabolic balance of aquatic ecosystems, their greenhouse gas (GHG, CO2, CH4, N2O) dynamics, the dynamics of organic matter, the patterns of carbon burial, and the downstream export of materials from fluvial networks, among other key ecosystem functions. We also know that inland waters may be major contributors to the carbon and radiative balance of watersheds, especially in landscapes such as our boreal biome. Watershed features and terrestrial inputs therefore play a key role in the biogeochemical and ecological functioning of aquatic networks, yet water networks also shape the material and C balance of watersheds, establishing a complex bidirectional link that is at the core of the functioning of water-rich northern landscapes. Whereas progress has been made over the past decade in quantifying and understanding individual aspects of the aquatic / terrestrial link, what is ostensibly lacking are studies that actually integrate the ensemble of aquatic / terrestrial interactions within a coherent framework, one that allows to explicitly assess these bidirectional relationships and feedbacks. My Discovery program will develop such a framework, through three objectives: 1) Integrate microbial community processes, the main aspects of carbon dynamics, and ecosystem metabolism within one single hydrologic framework; 2) Integrate these aspects at the scale of the whole aquatic network (streams, rivers, lakes); 3) Integrate these aquatic processes within a whole watershed balance. The core work will be carried out in a set of experimental watersheds located in Québec that differ in key properties, and therefore represent distinct aquatic / terrestrial link scenarios. In these watersheds we will establish a program that combines discrete sampling with continuous, high frequency measurements using autonomous instruments, remote sensing, hydrologic and landscape modeling, and cutting edge biogeochemical, isotopic and genomic approaches to assess GHG dynamics and fluxes, lake C burial and riverine export, river and lake metabolism, nutrient and organic matter dynamics, and the movement of organic molecules and microbes from land to watershed outlets. The program will yield unique case studies that will allow to unify existing patterns and evidence, test hypothesized links and identify emergent aquatic / terrestrial connections across a range of watershed types, and to model relationships and feedbacks between climate, watershed features and aquatic network functioning that will be used to predict shifts in landscape sink/source balances and biogeochemical and ecological functioning under future scenarios.