Sediment Resuspension Controls Light Attenuation and Ecosystem Function in a Large, Shallow, Eutrophic Lake

Light limitation constrains ecosystem function in large, shallow eutrophic lakes, yet the ecosystem-scale role of sediment resuspension is rarely isolated. We quantified wave- and bioturbation-driven resuspension effects on light attenuation in Utah Lake using repli-cated limnocorrals (~12 m diameter; 1.2–2.4 m depth) deployed over three growing seasons (2022–2024). Secchi depth (n = 363) and PAR profiles (7 depths; n = 126) were measured inside corrals and at paired open-lake controls. Mean Secchi depth was nearly twofold greater inside corrals (39.8 vs. 22.0 cm; p < 0.001), with lower light attenuation coefficients (k = 0.17 vs. 0.22). Ln(PAR) depth regressions consistently showed weaker attenuation under reduced disturbance, producing compensation depths 1.25× deeper inside corrals. Although near-surface PAR was sometimes higher in the open lake, PAR below 0.5 m was consistently greater inside corrals. Reduced attenuation was linked primarily to lower suspended solids and decreased resuspension of fine sediments and CaCO₃ precipitates; phytoplankton biomass further influenced late-summer attenuation. Sediment resuspension thus dominates underwater light climate, constrains benthic production, and reinforces phytoplankton-dominated pathways. Stabilizing sediments through invasive carp removal, macrophyte and mollusk recovery, and reduced dis-turbance should enhance light availability, benthic–pelagic coupling, and ecosystem function in turbid shallow lakes.