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REDUCED IRON AS A PRE-CONDITION FOR CYANOBACTERIAL DOMINANCE IN EMBAYMENTS ALONG GEORGIAN BAY, GREAT LAKES

Previous work suggests that a high rate of internal ferrous iron (Fe(II)) loading from anoxic sediments into overlying waters favours cyanobacteria dominance (> 50% of the biomass) over other phytoplankton. This Cyanobacteria-Ferrous model was assessed along the Georgian Bay coastline of Lake Huron, Canada in one meso-eutrophic and three oligotrophic embayments which experience natural anoxia. Cyanobacteria dominated the three embayments studied in warm 2012 but not the three embayments studied in cooler 2014 although sediment anoxia and internal Fe(II) loading were observed in both summers in all embayments. A large bloom was observed only in warm 2012 in the meso-eutrophic embayment. Results show that warm summer temperatures and internal Fe(II) loading are necessary for cyanobacteria dominance while high nutrient levels are also needed for large cyanobacteria blooms to form. There were no consistent patterns between cyanobacteria dominance and total and dissolved P, total N, ammonium and nitrate. Internal P loading was not a necessary precondition for cyanobacteria dominance. The implication for lake management from this and other studies is that while nutrient export controls are required to lower productivity and limit the size of phytoplankton blooms, oxidized surficial sediments must be maintained throughout an aquatic system to prevent cyanobacteria dominance of phytoplankton.

Authors

Molot, L., York University, Canada, lmolot@yorku.ca

Verschoor, M. J., York University, Canada, verschm@yorku.ca

Powe, C. R., York University, Canada, chris.powe@gmail.com

McQuay, E., University of Waterloo, Canada, emmcquay@uwaterloo.ca

Schiff, S. L., University of Waterloo, Canada, sschiff@uwaterloo.ca

Venkiteswaran, J. J., Wilfred Laurier University, Canada, jvenkiteswaran@wlu.ca

Li, J., York University, Canada, lmolot@yorku.ca

Details

Oral presentation

Session #:021
Date: 03/02/2017
Time: 10:00
Location: 323 B

Presentation is given by student: No