Excess phosphorus from fertilizer runoff causes much of the harmful algal blooms in Lake Erie. Now a group of researchers are studying what happens to those nutrients after they enter the lake.
A $500,000 grant from the United States Environmental Protection Agency Great Lakes Restoration Initiative will fund the research, led by a team from The University of Toledo. They will look closely at phosphorus — the most important nutrient in the growth of harmful algal blooms in fresh water — and how much remains in the lake even after the blooms end.For the first year of the project, researchers will dive to the lake bottom to place chambers that will allow them to measure the release of phosphorus from lake sediments. They also will bring lake sediment back to the laboratory and measure phosphorous, using probes created specifically for this project. The chambers and probes will indicate the amounts of phosphorous throughout the spring and summer months, revealing how much phosphorous is naturally recycled and how much remains in the water.
“We hope that the result of this research will be a better understanding of how phosphorus is recycled once it gets into Lake Erie,” said Dr. Thomas Bridgeman, UT associate professor of environmental sciences and project coordinator. “That will allow us to better predict the outcome of any management practices that are put in place.”
Researchers also will look at the watershed and agricultural practices, using computer models to predict what might happen under different climate scenarios. As the climate gets warmer and the growing season lengthens, algal blooms will grow larger if no steps are taken.
The state of Ohio is recommending reducing the amount of fertilizer runoff in the lake by 40 percent via new agricultural practices, which would restrict the growth of algae. However, the longer this reduction is delayed, the less effect it will have as the climate warms further.
“We want to have a better understanding of how climate change will affect harmful algal blooms in the future,” Bridgeman said. “This will allow researchers to make better recommendations to state agencies and the agricultural community about what needs to be done.”
Researchers from UT include Bridgeman, Dr. Ricky Becker, Dr. Song Qian and Dr. Christine Mayer from the Department of Environmental Sciences, as well as Dr. Yougwoo Seo from the Department of Civil Engineering, who developed the phosphorous probe.
Other researchers on the project are from Ohio State University, Heidelberg University, Case Western Reserve University, and the U.S. Geological Survey and Limnotech in Ann Arbor.
“We know that Lake Erie is a very resilient system, and we hope if we can reduce the amount of phosphorus that we put into the lake, it will recover very quickly,” Bridgeman said.