Presentation Abstract

At least 160 ha (30%) of the brackish marsh on Sturgeon Bank in the Fraser River estuary have disappeared since 1989. A collaborative effort between the provincial and federal governments and industry aims to determine the cause(s) of the recession to inform future restoration efforts. Three adjacent low-elevation brackish marshes along the delta front have also receded to varying degrees. River training structures and regular dredging of the Fraser River divert sediments and fresh water, and thus alter sediment and salinity patterns along the delta front. Lesser snow geese (Anser c. caerulescens) preferentially grub bulrush, and the Fraser-Skagit population has increased 2-3 fold over the last three decades. Investigation of the marsh recession to date includes (1) describing historical rates and patterns of recession, (2) assessing the present environment (e.g., sediment accretion rates and salinity regimes), and (3) conducting inferential experiments to identify factors that contribute to marsh loss and prevent recovery. No single recession hypothesis we tested singularly explains the recession. The anticipated effects of climate change, especially sea-level rise, pose additional threats to all tidal marshes in the Fraser River estuary.

Session Title

The Lower Fraser River: A Wildlife Hotspot on the Brink

Keywords

Marsh recession, Fraser estuary, Sturgeon Banks

Conference Track

SSE4: Ecosystem Management, Policy, and Protection

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE4-282

Start Date

6-4-2018 11:00 AM

End Date

6-4-2018 11:15 AM

Type of Presentation

Oral

Contributing Repository

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

Geographic Coverage

Salish Sea (B.C. and 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

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Apr 6th, 11:00 AM Apr 6th, 11:15 AM

Research into the cause of brackish marsh recession in the Fraser River estuary

At least 160 ha (30%) of the brackish marsh on Sturgeon Bank in the Fraser River estuary have disappeared since 1989. A collaborative effort between the provincial and federal governments and industry aims to determine the cause(s) of the recession to inform future restoration efforts. Three adjacent low-elevation brackish marshes along the delta front have also receded to varying degrees. River training structures and regular dredging of the Fraser River divert sediments and fresh water, and thus alter sediment and salinity patterns along the delta front. Lesser snow geese (Anser c. caerulescens) preferentially grub bulrush, and the Fraser-Skagit population has increased 2-3 fold over the last three decades. Investigation of the marsh recession to date includes (1) describing historical rates and patterns of recession, (2) assessing the present environment (e.g., sediment accretion rates and salinity regimes), and (3) conducting inferential experiments to identify factors that contribute to marsh loss and prevent recovery. No single recession hypothesis we tested singularly explains the recession. The anticipated effects of climate change, especially sea-level rise, pose additional threats to all tidal marshes in the Fraser River estuary.