12:00 pm, Tue October 29, 2024 – Researchers modeled complex phosphorus cycling in the Maumee River watershed to help mitigate blooms and inform sources of phosphorus
Phosphorus is an essential nutrient for sustaining life on Earth, influencing entire food webs by fueling photosynthetic organisms. However, in agricultural regions like the Western Lake Erie Basin, it’s possible to have too much of a good thing: too much phosphorus can cause an overgrowth of algae, creating harmful algal blooms (HABs).
Scientists know that phosphorus from the Maumee River watershed is the primary driver of a HABs’ size in western Lake Erie, but they are unsure how rivers and streams affect the transport of phosphorus into the lake. New interdisciplinary research funded by Ohio Sea Grant recently provided more insights about this phenomenon.
Researchers gathered data from from two sites at Potato Run and Shallow Run in northwest Ohio, focusing on phosphorus cycling during 10 days with stable flow in the summer.
“We really don’t know what happens to phosphorus in river systems between when it leaves agricultural fields and makes it into the lake,” said Dr. Jim Hood, an associate professor within the Department of Evolution, Ecology and Organismal Biology at The Ohio State University, who led the project. “It’s likely that rivers are influencing how much phosphorus enters Lake Erie and how available it is to organisms. What we don’t know is exactly how.”
To address this knowledge gap, Hood’s team worked to develop a new modeling approach to characterize how phosphorus cycles in the Maumee River watershed over time. To accomplish this, the project took advantage of high-frequency nutrient monitoring systems from the National Center for Water Quality Research(NCWQR) at Heidelberg University.
“The idea was to use that high-frequency data to build models that would actually help us understand how the phosphorus is cycling,” said Hood, who also serves as co-director of Ohio State’s Aquatic Ecology Laboratory. “The broader goal is to understand whether the streams are taking up or releasing phosphorus and how this changes over time.”
Many widespread watershed models assume that rivers transport nutrients downstream like a pipe, yet that’s not how streams work, Hood said. Streams are often reactive and changing, sometimes serving as a “sink” that stores phosphorus or a “source” that adds phosphorus to the water. Meanwhile, because phosphorus cycles are complex, measuring them in the field can be time-consuming and expensive.
