Submerged aquatic vegetation (SAV) are essential components of inland water ecosystems and provides many ecosystem services, such as supplying food and habitat for fauna and promoting a clear water state. These ecosystem services are threatened by the rapid changes in SAV quantities associated with various drivers, where the predominant decline in recent decades is due to eutrophication. However, this information comes from biased time series primarily located in temperate zones, measured through single recurrent annual inventories. Therefore, our understanding of both SAV ecology and their response to human activities is hampered by the lack of observations in the many lake-rich regions of the world and the limited description of the timing in SAV seasonal development. To improve knowledge on SAV geographic distribution and temporal evolution, we present an overview of methodological developments that we have conducted in recent years. We first show an intercalibration of three methods, quadrat, rake and echosounding, to facilitate the monitoring of SAV biomass at large spatial and temporal scale. We then discuss the use of the slope of water surface elevation as an indicator of biomass and how it allowed for the detection of detailed seasonal growth and phenological changes. We finally present a novel model to predict lake bathymetry from the surrounding topography, for a better estimate of littoral area at broad scales. In combination with information on light availability to SAV, the model will allow mapping and estimating change in potential SAV colonization area.

Primary Presenter: Morgan Botrel, Université de Montréal, Groupe de recherche interuniversitaire en limnologie (GRIL) (morgan.botrel@umontreal.ca)

Authors:

Roxane Maranger, Université de Montréal, Groupe de recherche interuniversitaire en limnologie  (r.maranger@umontreal.ca)