GESTAR II Seminar Series, August 8 at 11:00am

Tue, 06 Aug 2024 10:49:28 -0400
gestar2

Join us for a virtual seminar by Dr. Silvia Newell, Michigan Sea Grant and University of Michigan. Her talk is titled "Nitrogen as a Driver of Cyanobacterial Harmful Algal Blooms."

Date and Time: Thursday, August 8, 2024 at 11:00am EST

Join us via Webex.

Abstract:

"Cyanobacterial harmful algal blooms (HABs) are increasingly frequent and severe in lakes across the globe, negatively affecting ecosystem productivity, nutrient cycling, macrofauna, tourism, property values, access to potable water, public health, etc. The frequency of HABs is predicted to increase in the midwestern United States with increased storm events exacerbating agricultural nutrient runoff. Both nitrogen (N) and phosphorus (P) runoff contribute directly to HAB production, and excess N is associated with cyanotoxin production. In the Great Lakes region, targets for reduced P runoff into Lake Erie exist, but not for N. However, controls on N are needed to reduce toxic HABs. Knowledge gaps around the role of internal water column and sediment N recycling vs. external loading on HABs and toxicity have hindered a reduction recommendation for N runoff. Internal N recycling promotes cyanobacteria dominance, particularly for non-N-fixing taxa (e.g., Planktothrix and Microcystis), which have a competitive advantage for ammonium. However, ammonium is assimilated quickly by cells, and ambient concentrations are usually low; thus, internal N recycling rates are a more accurate representation of ammonium availability than concentration measurements, which are snapshots in space and time. Here, we report on the rates of internal and external N loading on HABs and microcystins in hypereutrophic Lake Erie and Grand Lake St Marys (Ohio). Including internal N recycling rates in models explains N sources during periods of low external loads and improves models of microcystin concentrations. Quantifying internal N cycling is therefore key to modeling and predicting microcystins."

Biography:

Dr. Silvia Newell is the Director of Michigan Sea Grant and a Professor at the University of Michigan School for Environment and Sustainability. She is a nutrient biogeochemist and microbial ecologist with experience working on Great Lakes issues. She researches the effects of excess nutrients from fertilizer and wastewater on inland and coastal waters, with a focus on harmful algal blooms in Lake Erie. She is currently funded through NSF Chemical Oceanography to study nitrogen dynamics in the Great Lakes, NSF DISES to work on nitrogen dynamics influencing nutrient loading to Lake Erie, the Ohio Department of Natural Resources to look at nutrient processing in constructed wetlands, NSF Chemical Oceanography to look at connections between nitrogen and mercury cycling in Antarctic coastal water, and the Great Lakes Fisheries Commission to look at ecosystem impacts on fish recruitment. Silvia also has experience engaging stakeholders to develop realistic pathways for nutrient reduction. Additionally, she serves on the board for a number of organizations (including the Earth Science Women’s Network, the Great Lakes Commission HABs Collaborative, the Saginaw Bay Monitoring Consortium Advisory Committee, the Science Advisory Panel for the Michigan Domestic Action Plan for Nutrient Reduction to Lake Erie) and is the current Past President of the Lake Erie Area Research Network.

For more information on the GESTAR II Seminar Series, click here.