Predicting the likelihood of a regime shift in Cootes Paradise with statistical & mechanistic models

Session: 04. - Restoring Hamilton Harbour: Tilting at Windmills or a Possible Dream?

Cindy Yang, University of Toronto, [email protected]
Tianna Peller, McGill University, [email protected]
Laud Matos, Environment and Climate Change Canada, [email protected]
George Arhonditsis, University of Toronto Scarborough, [email protected]

Abstract

Despite extensive restoration efforts, Cootes Paradise continues to be degraded and seemingly unable to revert back to its former clear state. Previous work has failed to address the spatial heterogeneity in the system when characterizing its ecological functioning. Our modelling study will evaluate the spatially-explicit ecosystem response in Cootes Paradise to: (1) nutrient reductions in wastewater treatment plant discharge and (2) the presence of submergent vegetation communities. The present modelling exercise combines our best ecological understanding of Cootes Paradise and observed data to draw predictions about the ecosystem response to nutrient loading reductions and re-establishment of submergent vegetation. We evaluated the combined effects of submergent vegetation and nutrient loading reductions, as projected by a calibrated eutrophication model. We then developed a Bayesian statistical model to analyze the spatial distribution of reduced nutrient loading impact and delineate areas in Cootes Paradise where the greater water quality improvements will likely occur. We conclude by discussing the various sources of uncertainty and additional remedial actions required in Cootes Paradise marsh to realize a shift from the current turbid-phytoplankton dominated state to its former clear-macrophyte dominated state.

1. Keyword
Hamilton Harbour

2. Keyword
submerged plants

3. Keyword
ecosystem modeling