A research team at Iowa State University is investigating whether engineered wetlands designed to improve water quality can also support biodiversity in ways similar to natural wetlands.
Led by Professor Charlie Loewen and supported by the Iowa Nutrient Research Center, the project focuses on Conservation Reserve Enhancement Program wetlands, which are strategically placed to intercept nitrogen-laden agricultural runoff. These constructed wetlands have proven effective at reducing nitrogen levels, but their potential to support robust ecosystems remains under study.
Loewen’s team is particularly interested in how nutrient imbalances — specifically the accumulation of phosphorus — might influence aquatic biodiversity. Unlike nitrogen, phosphorus is less effectively treated in CREP wetlands, leading to concerns about algal blooms, oxygen depletion and changes in the types of organisms that can thrive. Such nutrient shifts could unintentionally favor undesirable species like toxin-producing cyanobacteria.
To explore these dynamics, researchers studied nine CREP wetlands and compared them to three natural or restored reference wetlands across the Des Moines Lobe region. They collected data on water quality, nutrient levels and a range of biological indicators, including aquatic plants, phytoplankton, insects and zooplankton. Preliminary findings suggest nutrient ratios and oxygen conditions significantly shape wetland food webs, influencing which species dominate.
Full results are expected later this year and will be posted here. The project aims to inform how future treatment wetlands can be designed to maximize both water quality and ecological health.
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