At Apostle Islands Scientists Study Ecological Relationships in Lake Superior

Ben Turschak, a research partner from the University of Wisconsin-Milwaukee’s School of Freshwater Sciences, is pictured here as he prepares to service equipment at the Sand-West monitoring site.

Photo by Brenda Moraska Lafrancois

Scientists are working at Apostle Islands National Lakeshore to understand how nearby tributaries influence what is going on under the surface of Lake Superior. Dr. Brenda Moraska Lafrancois, Midwest Region Aquatic Ecologist for the National Park Service, is working with a team of experts to monitor a site to the west of Sand Island and a second site off Myers Beach. Each site features special monitoring instruments attached to tripods and anchored to the lake bottom. Instruments include a light logger, time-lapse camera, current profiler, temperature string (temperature loggers deployed at multiple depths on a line) and water quality sonde. The sonde measures temperature, conductivity, pH, chlorophyll, turbidity, and colored dissolved organic matter.

NPS Aquatic Ecologist Brenda Lafrancois records water quality conditions near Meyers Beach following the historic June 2018 flood event.

Photo by David VanderMeulen

In addition to this continuous monitoring, periodic water samples were collected and analyzed for phytoplankton composition, algal toxins, and nutrients. The data from these stations will help us understand how nutrients and organic carbon that enter Lake Superior from tributary rivers influence plankton production and food web structure in the lake.

During 2018, the monitoring station near Myers Beach did double duty, helping document impacts from a historic flood event in June and a notable algal bloom in August. Dr. Moraska Lafrancois and a team of researchers from the University of Minnesota's Large Lakes Observatory kept the nearshore monitoring equipment running throughout the season and collected water quality and algal samples from several tributary and nearshore sites. Results are being used to understand how flood events and algal blooms affect nearshore water quality and public safety.