Satellite-based assessment of coastal ocean productivity

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Vegetated coastal habitats provide numerous ecosystem services to humans and are among the most important carbon sinks worldwide, yet they remain poorly quantified. At a global scale, marine macrophytes living in intertidal and subtidal zones may contribute as much as 10% of the marine net primary production (NPP) but 47% of the carbon burial in sediments. Macrophytes are found in both the intertidal and subtidal zones; they include seagrass, which grows on silty and/or muddy sediments, and macroalgae, which grows on rocky substrates and boulders. We hypothesize that vegetated coastal ecosystems will expand toward the north as a response to climate warming. Arctic and subarctic expansion of vegetated coastal ecosystems may play an important role in future carbon sequestration along the long Canadian coast, but quantitative tools are lacking. My research program will assess the dynamics of coastal vegetation in near-shore and shallow-water environments, capitalizing on recent advances in satellite optical remote sensing technologies. The main objective of my proposal is to understand the current state and evolution of marine primary producers in the arctic and subarctic ecosystems. Specifically, I intend to: 1) assess long- and short-term changes in vegetated coastal ecosystems in subarctic and arctic environments using multispectral imagery from high to very high spatial resolution sensors; 2) explore the potential of optical remote sensing to quantify carbon-based processes such as NPP and/or organic carbon burial in coastal ecosystems; and 3) develop and validate prognostic models of spectral light and photosynthesis in the optically complex and shallow waters encountered in subarctic coastal waters. Fieldwork will be performed in coastal zones along a south-to-north gradient, from subarctic (estuary and gulf of St. Lawrence, James Bay) to the High Arctic (Southampton Is., Pond Inlet, and Bylot Is.) environments. Fourteen HQP (6 B.Sc., 4 M.Sc., 3 Ph.D., and 1 PDF) will be trained in a highly interdisciplinary environment, learning satellite image processing, geomatics, in situ aquatic optics, numerical modelling, and computer programming; all these areas of expertise are expected to be in high demand as the needs in monitoring coastal ecosystems increase and Earth Observation technologies improve and produce increasingly high-quality data. This project will have incidence decision makers, coastal northern communities, First Nations, and NGOs in conservation for preservation and restoration efforts because of the new knowledge on the state and the evolution of the coastal ecosystems. Quantitative tools developed by this program will contribute to assessing the socio-economic importance of vegetated coastal ecosystems, which is particularly true in the context of the Blue Carbon strategy of the climate change mitigation strategy. Carbon stock may be converted into monetary values and therefore help in decision-making processes.