Co-supervised by:

David Didier (Regular member)

Research project description

Optical water quality in contrasting arctic coastscapes and its implication for macrophytes using remote sensing

IntroductionArctic coastal ecosystems undergo various changes due to retreating glaciers, decreasing sea ice, and the connectivity of land and sea. While some changes are assumed to be beneficial for the northward expansion of macrophytes, the availability of benthic light (in the form of photosynthetically active radiation, PAR) strongly varies between regions and increased turbidity might pose an impediment to their productivity. For inaccessible areas of the eastern Canadian Arctic, however, knowledge gaps exist for physicochemical conditions in the nearshore zone and distribution of benthic vegetation (e.g., kelps). Satellite derived measurements of optically active compounds that drive light attenuation in the water column might serve as crucial metrics to assess the evolution of optical water quality and habitat. Recent optical sensors (e.g., MSI or OLI sensors) have a spatial resolution that is, furthermore, able to resolve differences for the dynamic coastal zone on a local to regional scale. ObjectivesThe overarching aim of this research is to expand the current knowledge on fluxes in and ecological effects of light availability in the understudied arctic coastscapes as well as to improve the quantification in space and time through satellite-borne ocean colour remote sensing. This project will therefore (1) build relationships of spectral signature of surface waters and the optical water quality characterized by substances and particles therein, (2) use environmental data in combination with time-series analysis of satellite data to explore environmental forcing of changing benthic light conditions, in order to (3) classify regional characteristics in different coastscapes that might shape habitats for benthic vegetation, such as kelp. Study sitesField campaigns were accomplished in eastern James Bay (52°N) between 2018 and 2021 by JB COast UQAR research group (PI Urs Neumeier, UQAR-ISMER). The eastern coast of James Bay is an optically complex area influenced by varying contributions from the surrounding boreal landscape. The project will use these existing in-situ datasets for analysis and validation of satellite products. Other study sites will be sampled in Grise Fjord (Aujuittuq) (76°N) under consideration of the differences between coastscapes (such as fjords, estuaries, and eroding permafrost coasts). Material and methodsWe will use a combination of high-resolution satellite imagery - in particular the data from the Sentinel-2 mission from the European Space Agency - in ocean colour remote sensing as well as field measurements of optical, ecological, and oceanographic parameters to address the research problem. In the Arctic, Sentinel-2 has overpasses nearly daily, which is increasing the chance to obtain high resolution maps of surface and subsurface optically active compounds with spatial resolution as high as 10 or 20 m. Here, we will assess fluxes in optically active CDOM and SPM in the shallower nearshore zone of chosen study sites. References(selected relevant literature) 1.Krause-Jensen, D. et al. Imprint of Climate Change on Pan-Arctic Marine Vegetation. Frontiers in Marine Science 7, 1–28 (2020). 2.Forbes, D. L. Arctic Deltas and Estuaries: A Canadian Perspective. Coasts and Estuaries: The Future (Elsevier Inc., 2019). 3.Filbee-Dexter, K., Wernberg, T., Fredriksen, S., Norderhaug, K. M. & Pedersen, M. F. Arctic kelp forests: Diversity, resilience and future. Global and Planetary Change 172, 1–14 (2019). 4.CAFF. Arctic Coastal Biodiversity Monitoring Plan (CAFF Monitoring Series Report no. 29) (Issue May). (2019). 5. IOCCG. Earth Observations in Support of Global Water Quality Monitoring. IOCCG Report Series, No. 17, International Ocean Colour Coordinating Group, Dartmouth, Canada. Reports and Monographs of the International OceanColour Coordinating Group, 17, 132. (2018).

Research Site Coordinates