Master of Science (M.Sc.)
Virginia Institute of Marine Science
Environmental degradation of the Chesapeake Bay (CB) and its sub-estuaries has been linked to population growth in the surrounding coastal zone, rapid development in the watershed and resultant nutrient loading into the Bay. Consequently, the federal government and its partners have developed restoration plans to mitigate the effects of eutrophication and improve essential ecosystem functions, though few restoration plans have considered the interactive effects of climate change. Climate change and other anthropogenic drivers are causing changes in ecosystem structure and function, thereby impacting the beneficial services ecosystems provide. While some studies have attempted to quantitatively predict the benefits of ecosystem restoration under current conditions, research is needed to determine whether restored systems will be sustainable and continue to provide ecosystem services under changing conditions. This study examined how climate warming and sea level rise (SLR) might affect the sustainability of ecosystem services resulting from the proposed U.S. Army Corps of Engineers (USACE) Lynnhaven River Basin Ecosystem Restoration Plan (LRBERP). A system-wide prediction of marsh survival in the Lynnhaven was calculated by estimating the time period when Spartina alterniflora (smooth cordgrass) would submerge based on predicted sea level rise and marsh accretion for the region. In addition, a reduced complexity ecosystem model was applied to the Lynnhaven River to evaluate survival and sustainability of ecosystem services provided by S. alterniflora, Zostera marina (eelgrass), Ruppia maritima (widgeon grass), and Crassostrea virginica (Eastern oyster) reef habitat, under existing conditions as well as predicted climate warming (+1, 2, 3, and 5 °C) and sea level rise (+0.49, 0.99, 1.69, 2.29 m) scenarios for the region. The major findings from the model simulations and marsh analysis indicate that climate warming and SLR will affect the sustainability and capacity of restored submerged aquatic vegetation (SAV), oysters and marsh habitat to provide ecosystem services in the Lynnhaven River. This investigation calls into question the assumption that marshes will accrete indefinitely to keep pace with accelerating rates of sea level rise. Predicted submergence of S. alterniflora marshes by 2100 will limit their capacity to provide ecosystem services. Model predictions of S. alterniflora biomass decreased across the temperature scenarios with complete die-off under the +5°C scenario. Z. marina and R. maritima biomass decreased across the SLR scenarios with complete die-off of R. maritima under the 0.49 m scenario. This modeling result is consistent with the literature that R. maritima is more sensitive to light limitation than Z. marina. Z. marina biomass decreased across the temperature scenarios with complete die-off under the 5°C scenario whereas R. maritima biomass increased under the temperature scenarios. The positive effects of warming on R. maritima were offset by the negative impacts from SLR. There was a complete die-off of Z. marina and R. maritima biomass under the combined SLR/temperature scenario. The combination of stressors will likely have negative effects on Z. marina and R. maritima biomass in the polyhaline section of the Bay.
© The Author
Skeehan, Emily E., "Assessing the Impact of Climate Change on Proposed Restoration of the Lynnhaven River Ecosystem" (2015). Dissertations, Theses, and Masters Projects. William & Mary. Paper 1539617957.