On the role of physical processes in algal bloom formation in Lake St Clair

Session: Harmful Algal Blooms and Their Toxicity: Remote Sensing and Modeling Approaches (1)

Serghei Bocaniov, University of Waterloo, [email protected]
Homa Kheyrollah Pour, University of Waterloo, [email protected]
Donald Scavia, University of Michigan, [email protected]
Philippe Van Cappellen, University of Waterloo, [email protected]

Abstract

Algal blooms, or elevated phytoplankton concentrations, in lakes are triggered by a complex interplay of physical, chemical and biological processes. These processes can operate on different temporal and spatial scales. The importance of these processes and their combinations have been investigated in many studies, but yet, the role of seasonal lake-scale physical processes in creating the potential for the formation of algal blooms are not well understood, especially in large, dynamic and transport-dominated lakes, such as Lake St Clair. The latter is a large lake (>1100 km²) with a very short flushing time (mean ±SD:  9.1 ±0.4 days), which is expected to limit the lake’s primary production and prevent significant accumulation of algal biomass within the lake. However, there are frequent satellite-based observations of localized moderate-sized algal blooms in the south-eastern part of the Lake St Clair. Here, we use a combination of three-dimensional (3D) process-based lake modeling, integrated with remote sensing observations, to delineate the significant role of physical processes in creating the ideal conditions for blooms formation in Lake St Clair.