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WATER COLUMN AMMONIUM DYNAMICS AFFECTING HARMFUL CYANOBACTERIAL BLOOMS IN LAKE ERIE (E)

Cyanobacterial harmful algal blooms (HABs) in western Lake Erie are largely driven by agricultural nitrogen (N) and phosphorus from the Maumee River watershed. Cyanobacterial dominance and HAB development may depend on ammonium availability, and increased ammonium has been linked to toxin production. 15N tracers were used to quantify rates of ammonium regeneration and potential uptake, ammonia oxidation to nitrite (the first step of nitrification), and total nitrification. Ammonia oxidation and total nitrification rates were comparable to coastal ocean rates. However, nitrification rates were an order of magnitude lower than total community ammonium uptake rates, indicating that ammonia oxidation and nitrification are not the dominant uptake pathways. During non-bloom months, regeneration rates could account for approximately 80% of potential community uptake, but during the height of the bloom, when community ammonium demand was much greater, regeneration could only support 44% of potential uptake. These results suggest that management of external total N loads, which are readily converted to ammonium, may be necessary to reduce bloom biomass and toxicity.

Authors

Hoffman, D. K., Wright State University, USA, dprhoffman@gmail.com

McCarthy, M. J., Wright State University, USA, mjm.kingston@gmail.com

Davis, T. W., NOAA Great Lakes Environmental Research Laboratory, USA, timothy.davis@noaa.gov

Gossiaux, D., NOAA Great Lakes Environmental Research Laboratory, USA, duane.gossiaux@noaa.gov

Burtner, A., University of Michigan Cooperative Institute for Limnology and Ecosystems Research, USA, aburtner@umich.edu

Johengen, T., University of Michigan Cooperative Institute for Limnology and Ecosystems Research, USA, johengen@umich.edu

Palladino, D., University of Michigan Cooperative Institute for Limnology and Ecosystems Research, USA, dpallad@umich.edu

Gardner, W. S., The University of Texas at Austin, Marine Science Institute, USA, wayne.gardner@utexas.edu

Myers, J. A., Wright State University, USA, myers.161@wright.edu

Newell, S. E., Wright State University, USA, silvia.newell@wright.edu

Details

Oral presentation

Session #:021
Date: 03/01/2017
Time: 16:30
Location: 323 B

Presentation is given by student: Yes