The UTC Graduate School is pleased to announce that Hannah Kirtlink will present Master’s research titled, Aquatic Ecosytems Under Pressure: Landscape and Biological Influences on Organic Matter Decomposition in Streams of the Tennessee River Watershed on 10/28/2026 at 12:00 pm in Holt 123. Everyone is invited to attend.
Environmental Science
Chair: Richard H. Walker
Co-Chair:
Abstract:
Freshwater ecosystems are increasingly affected by anthropogenic stressors, including altered land use, nutrient loading, and hydrologic modification, which can influence biogeochemical processes. I conducted a 140-day organic matter (OM) decomposition study in 18 streams across the Tennessee River watershed, spanning gradients of land use and flow intermittency. I used piecewise structural equation modeling (PSEM) to evaluate direct and indirect relationships among landscape, hydrologic, habitat, water-quality, and biological variables and OM decomposition rates (k). Macroinvertebrate abundance was the strongest direct predictor of decomposition, with greater abundances associated with faster decomposition. Land use and substrate composition were indirectly associated with decomposition through their relationships with macroinvertebrate abundance. Water quality was associated with microbial activity, but microbial activity was not retained as a predictor of decomposition in the final model. These findings highlight the complexity of landscape conditions and biological communities in shaping decomposition patterns across streams with differing environmental characteristics.