Grant: Discovery Grants Program - Individual

Freshwater ecosystems are biogeochemical hotspots embedded in the terrestrial landscape that undergoes rapid human-driven changes such as agriculture and urbanization. Central to this role are the metabolic activities of heterotrophic bacteria, which are responsible for most of the degradation and mineralization of the organic matter (OM) transiting in inland waters in addition to providing nutrients and energy to the aquatic food web. Despite the recognition of this role at the ecosystem level, little is known about how and to which extent anthropogenic disturbances may alter the metabolism and functioning of aquatic microbial communities through changes in the amount, chemical character, and age of the OM delivered to surrounding waters. Conducting research at the interface of microbial ecology and aquatic biogeochemistry, I propose to further our understanding of the links existing between microbial metabolism and the molecular properties of OM across perturbation gradients to better understand and predict the overall ecosystemic response of inland waterbodies to human activities. The main objectives of my research program are to: (i) identify the organic molecules released into the aquatic interface along gradients in land-cover from forested landscapes to agriculture and urban areas, (ii) assess the microbial strategies involved in the uptake of the mobilized organic pool by human activities, and (iii) determine the metabolic response of aquatic bacterial communities along perturbation gradients. Relying on state-of-the-art technics in analytical chemistry and unique experimental approaches, my research program will combine temporal and spatial field-based surveys in the Mauricie region of Québec taking advantage of the large gradient in anthropogenic influence present in this region, as well as laboratory assays shedding light into the bacterial strategies of resource utilization in representative impacted systems. This program represents a crucial step towards an integrative understanding of how human disturbance may disrupt not only the flow of elements at the land-water interface, but also the functioning of aquatic food webs and ecosystems. This understanding will in turn allow scientists and policy makers to forecast the response of aquatic ecosystems and food webs to human pressure and to direct the most pressing restoration efforts in impacted watersheds.