What Can Ancient Sediments Tell Us About Lake Erie? (2024)

By studying deep layers of sediment found at the bottom of Lake Erie, scientists can tell a story about its past: how oxygen and pH levels in the lake changed over the course of thousands of years, and how sediment followed different patterns as it accumulated.

Next, researchers can take these findings a step further, learning how sediments accumulate today and gleaning insights about how low-oxygen zones and harmful algal blooms form on the lake.

That’s the subject of a newly funded Ohio Sea Grant research project led by Dr. Beverly Saylor of Case Western Reserve University. With work getting underway this year, her team plans to extract new sediment “cores” — cylindrical sections that capture the lake’s deep layers — and gather high-resolution data to improve sediment modeling and monitoring.

“Our primary goal is to understand which areas are accumulating sediments today and which are not, and to establish timescales of deposition and erosion,” said Saylor, a professor at Case Western’s Department of Earth, Environmental, and Planetary Sciences. “Does sediment accumulate during quiet periods and then erode during major storm events?”

On Lake Erie, sediments bring nutrients and contaminants such as phosphorus and heavy metals into the lake, store them on the lake floor, and release them into the water.

“Erosion can recycle these elements, making them, potentially, an important internal source of pollutants,” Saylor said. “The variation in thickness of sediments across the basin can tell us about where sediments are accumulating and are a sink for pollutants and where they are being eroded and may be a source.”

“This project holds the promise of improved modeling and monitoring of sediment accumulation in Lake Erie’s central basin and can help practitioners and policymakers to better understand one of the factors that may contribute to hypoxia and anoxia.”
Dr. Beverly Saylor

Through previous research, Saylor and others used sediment cores to document how low oxygen conditions arose in Lake Erie thousands of years ago, driven by changes in lake level. Researchers also found evidence that large offshore areas of the lake’s central basin have accumulated very little sediment over time.

Now, Saylor’s team plans to collect new sediment cores that are 10-20 feet long and use them as a record of lake conditions over the past 5,000 years and more. The project is a collaboration among researchers at multiple universities, including Dr. Onema Adojoh of Northern Missouri State University, Dr. Joseph Ortiz of Kent State University, Dr. John Peck of the University of Akron, and Dr. Mohamed Zobaa at University of Texas Permian Basin.

“Sediment composition and fossils can tell us about past oxygen levels and pH in the bottom waters and may also provide evidence for algal blooms and landscape disturbance that we can relate to changes in lake level and climate,” Saylor said.

To collect the cores, the team will “piggyback” off of monitoring and research work being done aboard the U.S. Environmental Protection Agency’s Research Vessel Lake Guardian. Researchers will collect both long and short cores at different locations across Lake Erie, cut them into segments, and transport them to the University of Minnesota’s Continental Scientific Drilling Facility.

There, the team will scan cores for their magnetic properties and elemental composition, split them lengthwise, and sample them further. Researchers will date the cores using different methods that work best for different time periods, including paleomagnetic variation, carbon dating, and pollen analysis.

By developing a record of sedimentation over thousands of years, the team will be able to establish links between hydrology, climate, and low-oxygen conditions.

“This project holds the promise of improved modeling and monitoring of sediment accumulation in Lake Erie’s central basin and can help practitioners and policymakers to better understand one of the factors that may contribute to hypoxia and anoxia,” Saylor said.

Specifically, results may help inform managers taking steps to reduce nutrient loading from sediment deposition on Lake Erie. Insights may also explain how regional climate variation will impact future sediment movement and accumulation.

For more information about this newly funded research project, set to end in spring of 2026, contact Dr. Saylor at bzs@case.edu.

Ohio Sea Grant is supported by The Ohio State University College of Food, Agricultural, and Environmental Sciences (CFAES) School of Environment and Natural Resources, Ohio State University Extension, and NOAA Sea Grant, a network of 34 Sea Grant programs nation-wide dedicated to the protection and sustainable use of marine and Great Lakes resources. Stone Laboratory is Ohio State’s island campus on Lake Erie and is the research, education, and outreach facility of Ohio Sea Grant and part of CFAES School of Environment and Natural Resources.