Presentation Title

Habitat suitability for eelgrass following large scale tidal restoration on the Nisqually Delta

Session Title

Remote sensing technology to monitor the short and long term dynamic of the Salish Sea

Conference Track

Habitat

Conference Name

Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type of Presentation

Oral

Abstract

Large-scale estuary restoration, such as the removal of dams or dikes, can alter nearshore processes and provide an opportunity to study how ecosystems respond to changes in the physical environment. In this study, we quantify changes in the spatial distribution of eelgrass Zostera marina following a 2009 dike-removal project that restored tidal processes to over 350 ha of the Nisqually River delta. We produced high resolution maps of eelgrass percent cover, depth distribution, and nearshore bathymetry from surveys performed in 2012 and 2014 using a Biosonics 430 kHz single-beam echosounder and survey-grade global navigation satellite system. A coupled hydrodynamic and sediment transport model is used to characterize hydrodynamics (water levels, tidal currents, waves) and water column properties (salinity and turbidity) before and after dike removal. Model simulations suggest that removal of the dikes increased the tidal prism and altered sediment transport pathways on the delta. We explore how modeled changes in the hydrodynamics, turbidity, and morphology following restoration relate to eelgrass cover, depth distribution, and habitat suitability for eelgrass on the Nisqually delta. Such relationships provide insight into the physical mechanisms driving ecosystem responses and can improve the capacity to predict changes in nearshore habitats following restoration or other land-scape modifications including climate change.

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.

Language

English

Format

application/pdf

Type

Text

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Habitat suitability for eelgrass following large scale tidal restoration on the Nisqually Delta

2016SSEC

Large-scale estuary restoration, such as the removal of dams or dikes, can alter nearshore processes and provide an opportunity to study how ecosystems respond to changes in the physical environment. In this study, we quantify changes in the spatial distribution of eelgrass Zostera marina following a 2009 dike-removal project that restored tidal processes to over 350 ha of the Nisqually River delta. We produced high resolution maps of eelgrass percent cover, depth distribution, and nearshore bathymetry from surveys performed in 2012 and 2014 using a Biosonics 430 kHz single-beam echosounder and survey-grade global navigation satellite system. A coupled hydrodynamic and sediment transport model is used to characterize hydrodynamics (water levels, tidal currents, waves) and water column properties (salinity and turbidity) before and after dike removal. Model simulations suggest that removal of the dikes increased the tidal prism and altered sediment transport pathways on the delta. We explore how modeled changes in the hydrodynamics, turbidity, and morphology following restoration relate to eelgrass cover, depth distribution, and habitat suitability for eelgrass on the Nisqually delta. Such relationships provide insight into the physical mechanisms driving ecosystem responses and can improve the capacity to predict changes in nearshore habitats following restoration or other land-scape modifications including climate change.