Assessing Padilla Bay’s response to sea level rise with a hybrid ecogeomorphic model
Presentation Abstract
Estuaries worldwide are facing the possibility of conversion to open water if accretion cannot keep pace with increasing rates of eustatic sea level rise (ESLR). Recent research into sediment elevation dynamics in Padilla Bay, a National Estuarine Research Reserve in Puget Sound, has revealed a mean bay-wide elevation deficit of -0.39 cm/year since 2002. However, a more mechanistic prediction of the estuary’s response to future ESLR should also incorporate non-linear feedback mechanisms between water depth, plant biomass, and sediment deposition. Therefore, we used the field data collected as part of this research (measurements of sediment accretion rates, suspended sediment concentrations, eelgrass stem density, and above- and belowground eelgrass biomass) to build and calibrate a marsh equilibrium model (MEM), developed elsewhere but applied here for the first time to this eelgrass-dominated intertidal habitat. We then coupled the MEM with a relative elevation model (REM) which has previously been applied here, to create a hybrid model that combines each model’s strengths in mechanistically simulating above- and belowground processes, respectively. The model predicts elevation change under various ESLR and suspended sediment scenarios. We used an 11-year elevation change dataset obtained from an extensive surface elevation table (SET) network in Padilla Bay for model validation. Here we present preliminary results suggesting sediment accretion rates to be primarily determined by stem density instead of plant biomass or water depth. Because the non-native eelgrass, Zostera japonica, grows in higher densities than the native Z. marina, Z. japonica may provide a disproportionate contribution toward maintaining elevation in the face of sea level rise in this sediment-starved estuary.
Session Title
Session S-07H: Assessing, Planning and Adapting to Climate Change Impacts in Skagit River Watershed
Conference Track
Shorelines
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
1-5-2014 3:30 PM
End Date
1-5-2014 5:00 PM
Location
Room 607
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Estuarine sediments--Washington (State)--Padilla Bay--Mathematical models; Sea level--Washington (State)--Padilla Bay--Mathematical models; Eelgrass--Ecology--Washington (State)--Padilla Bay--Mathematical models; Climatic changes--Washington (State)--Padilla Bay--Mathematical models
Geographic Coverage
Salish Sea (B.C. and Wash.); Padilla Bay (Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Assessing Padilla Bay’s response to sea level rise with a hybrid ecogeomorphic model
Room 607
Estuaries worldwide are facing the possibility of conversion to open water if accretion cannot keep pace with increasing rates of eustatic sea level rise (ESLR). Recent research into sediment elevation dynamics in Padilla Bay, a National Estuarine Research Reserve in Puget Sound, has revealed a mean bay-wide elevation deficit of -0.39 cm/year since 2002. However, a more mechanistic prediction of the estuary’s response to future ESLR should also incorporate non-linear feedback mechanisms between water depth, plant biomass, and sediment deposition. Therefore, we used the field data collected as part of this research (measurements of sediment accretion rates, suspended sediment concentrations, eelgrass stem density, and above- and belowground eelgrass biomass) to build and calibrate a marsh equilibrium model (MEM), developed elsewhere but applied here for the first time to this eelgrass-dominated intertidal habitat. We then coupled the MEM with a relative elevation model (REM) which has previously been applied here, to create a hybrid model that combines each model’s strengths in mechanistically simulating above- and belowground processes, respectively. The model predicts elevation change under various ESLR and suspended sediment scenarios. We used an 11-year elevation change dataset obtained from an extensive surface elevation table (SET) network in Padilla Bay for model validation. Here we present preliminary results suggesting sediment accretion rates to be primarily determined by stem density instead of plant biomass or water depth. Because the non-native eelgrass, Zostera japonica, grows in higher densities than the native Z. marina, Z. japonica may provide a disproportionate contribution toward maintaining elevation in the face of sea level rise in this sediment-starved estuary.
