Impact of Climate Change and Restoration on Phosphorus Loading in an Impaired Wetland
Location
Hager-Lubbers Exhibition Hall
Description
PURPOSE: Restoring wetlands increases biodiversity and water quality within surrounding ecosystems; however, failing to consider past land uses can result in negative water quality effects. Prior agricultural practices at a coastal wetland restoration site have caused high legacy phosphorus (P) concentrations in sediments. Sediment dredging is being considered as a restoration tool to control internal phosphorus loading (IPL). Climate warming is resulting in increases to both mean temperature and temperature extremes, which may affect IPL. SUBJECTS: Sediment cores (72) were taken for experiment. METHODS AND MATERIALS: We simulated dredging in half of the sediment cores and incubated them under three climate regimes: ambient, ambient+3°C, and a variable regime with heat waves. We measured water column and sediment phosphorus levels throughout the incubation to understand phosphorus dynamics. ANALYSES: We used a two-way ANOVA to determine the effects of dredging and temperature treatments. RESULTS: Unexpectedly, dredged sediment cores had higher SRP release rates in both ponds (north ~22 mg L-1 d-1, south ~1.9 mg L-1 d-1) compared to undredged cores (north ~18.6 mg L-1 d-1, south ~1.5 mg L-1 d-1). Elevated temperature and variability regimes increased P release and accumulation, but only in the less enriched south pond. Equilibrium P concentrations suggest sediments are a source of SRP to overlying water column regardless of dredging treatment. CONCLUSIONS: Our results emphasize the need for precursory research and show that dredging might not be the ideal management technique for this restoration site. Additionally, warming temperatures will exacerbate IPL in the future without management.
Impact of Climate Change and Restoration on Phosphorus Loading in an Impaired Wetland
Hager-Lubbers Exhibition Hall
PURPOSE: Restoring wetlands increases biodiversity and water quality within surrounding ecosystems; however, failing to consider past land uses can result in negative water quality effects. Prior agricultural practices at a coastal wetland restoration site have caused high legacy phosphorus (P) concentrations in sediments. Sediment dredging is being considered as a restoration tool to control internal phosphorus loading (IPL). Climate warming is resulting in increases to both mean temperature and temperature extremes, which may affect IPL. SUBJECTS: Sediment cores (72) were taken for experiment. METHODS AND MATERIALS: We simulated dredging in half of the sediment cores and incubated them under three climate regimes: ambient, ambient+3°C, and a variable regime with heat waves. We measured water column and sediment phosphorus levels throughout the incubation to understand phosphorus dynamics. ANALYSES: We used a two-way ANOVA to determine the effects of dredging and temperature treatments. RESULTS: Unexpectedly, dredged sediment cores had higher SRP release rates in both ponds (north ~22 mg L-1 d-1, south ~1.9 mg L-1 d-1) compared to undredged cores (north ~18.6 mg L-1 d-1, south ~1.5 mg L-1 d-1). Elevated temperature and variability regimes increased P release and accumulation, but only in the less enriched south pond. Equilibrium P concentrations suggest sediments are a source of SRP to overlying water column regardless of dredging treatment. CONCLUSIONS: Our results emphasize the need for precursory research and show that dredging might not be the ideal management technique for this restoration site. Additionally, warming temperatures will exacerbate IPL in the future without management.