Assessment of Water Quality Index, Light Attenuation, and Nutrient Sequestering by Submerged Aquatic Vegetation in the Detroit River
Date of Award
Great Lakes Institute for Environmental Research
Nutrient sequestering, Nutrients, Submerged aquatic vegetation, Vegetation, Water quality, Water quality index, Light attenuation, Detroit River
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This thesis assessed water quality – submerged aquatic vegetation interactions in the Detroit River. Submerged aquatic vegetation provides essential ecosystem services that support aquatic biodiversity and regulating ecosystem services such as carbon sinks, purifying water and nutrient cycling. Chapter 2 explored how degraded water quality in the Detroit River limits submerged aquatic vegetation via light limitation. A water quality index and light extinction coefficients were measured at 21 sites along with installation of in-situ water quality sondes at 4 sites to measure water quality at high temporal resolution. The river wide median euphotic depth was estimated to be 1.30 m, higher (1.34 m) at sites without tributary inflow compared sites that receive tributary inflow (0.83 m). Measured light extinction coefficients were correlated with water quality index scores. However, a multivariate PCA model predicting light extinction coefficient from chlorophyll a, turbidity and specific conductivity yielded the best prediction. Light attenuation appears to be driven by different water quality constitutes at different sites and over time. Chapter 3 tested nutrient drawdown by submerged aquatic vegetation at 5 wetlands. There was no evidence for phosphorus drawdown but nitrogen drawdown was apparent at one bed site. This thesis supports a conclusion for light limitation of submerged aquatic macrophytes at tributary influenced locations implying actions to improve tributary water quality will benefit the Detroit River. However, expanding macrophyte bed coverage is unlikely to address phosphorus reduction targets mandated for the Detroit River.
Scannell, John, "Assessment of Water Quality Index, Light Attenuation, and Nutrient Sequestering by Submerged Aquatic Vegetation in the Detroit River" (2023). Electronic Theses and Dissertations. 8958.