English Summary
Coastal oceanography of the eastern James Bay is complex due to the presence of numerous islands, its poorly documented bathymetry, and important fresh water discharges from several major rivers. Eelgrass beds (Zostera marina), known as important marine ecosystems providing both habitat and food for birds and fishes, have decreased drastically along this coast in the late 1990’s and have only partially recovered since. The reasons for these fluctuations are not understood so far, though the eelgrass health depends generally upon water and seabed properties, the bathymetry and the intra- and inter-annual variations of these parameters. Therefore, this new project aims to better understand the coastal oceanography of the eastern James Bay and to investigate stressors influencing eelgrass beds. The objectives are to: (1) determine seasonal and annual changes in coastal water characteristics and the dynamic of the river discharge plumes, (2) determine the sediment composition and sediment dynamics in key areas with and without eelgrass, and (3) determine environment evolution during the last century from sediment cores. Several field campaigns will be carried out from fall 2017 to summer 2019 to follow the seasonal evolution of water properties in and around eelgrass beds and to characterize the spatial sediment distribution. Water column profiles will record salinity, temperature, dissolved oxygen, turbidity, and photosynthetically available radiation. In addition, water samples will be collected to analyze nutrients, stable oxygen isotopes (δ18O), colored dissolved organic matter (CDOM), dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), particulate organic carbon and nitrogen (POC and PON), stable carbon and nitrogen isotopes (δ13C and δ15N) of organic particulate matter, suspended particulate matter (SPM), and photosynthetic pigments. The bathymetry of eelgrass beds and nearby areas will be surveyed yearly to observe seabed morphology, characterize the eelgrass habitat and determine stability of bedforms and sediments. Surface sediment samples will be analyzed for grain size, organic geochemistry, and bulk mineralogy. Sediment cores will be taken to document the sedimentation rates, changes in sediment composition, variations in palynology content, and consequently past environmental conditions during the last century. The water circulation of the James Bay will be modeled using the Regional Oceanographic Model developed for the Hudson Bay (ROM-HB), which is coupled to a sea ice simulator. The general grid will be refined to study water circulation and salinity distribution for the eastern James Bay. This research project is financed by Niskamoon Corporation, a Cree organization, and it is carried out in collaboration with the local Cree communities.
