AUTHORS: Shaley M. Klumker, Ryan A. Skowronski, Eden L Effert-Fanta
ABSTRACT: Many small streams traverse the agriculturally dominated Midwest, playing an important role in irrigation and drainage. However, these agricultural practices are major drivers of stream degradation. This study investigates the ecological impact and recovery of a Midwestern stream in North Central Illinois following a 20,000-gallon (75,708 L) spill of 28 Urea Ammonium Nitrate (UAN) fertilizer in late March 2024, which caused a large-scale fish kill extending about 32 km from the spill site. Fish recovery was monitored using monthly electrofishing surveys in both the impacted stream and a nearby, unimpacted stream within the same basin as a control. Habitat quality assessments and benthic macroinvertebrate surveys were also conducted to further evaluate stream ecosystem recovery over time. Changes in fish species abundance and diversity as well as the macroinvertebrate EPT (Ephemeroptera, Plecoptera, Trichoptera) Index served as quantitative measures of stream recovery. Preliminary results demonstrate an increase in catch per unit effort (CPUE) and species richness of fishes collected over the sampling period (approximately 2-6 months post-spill). Additionally, environmental DNA (eDNA) sampling was explored as a minimally invasive method of fish biodiversity assessment that may provide a better indication of the presence of sensitive or elusive taxa that traditional electrofishing methods may miss. Understanding patterns of stream recovery over time and utilizing novel methods such as eDNA is necessary to enhance our ability to respond to pollution events in vulnerable, agriculturally influenced systems.
