Event Title

A search for eelgrass blue carbon across Skagit County bays

Presentation Abstract

Seagrass meadows help mitigate climate change by taking up and storing (sequestering) carbon (C), reportedly at rates only surpassed worldwide by salt marsh and mangrove ecosystems. Now that their climate mitigation capacity has earned seagrass ecosystems a place in the Verified Carbon Standard voluntary GHG program, accurate ecosystem C accounting is essential and coastal ecologists are racing to fill current data gaps. Though seagrasses vary in C storage and accumulation greatly across species and geography, the bulk of data included in calculating global averages involves tropical and subtropical seagrasses. We know little regarding C stocks nor sequestration rates for eelgrass (Zostera marina) meadows in the Salish Sea. The intent of two studies in Padilla, Skagit, and Samish Bays was to quantify carbon stocks and sequestration rates and to compare them to studies occurring simultaneously both locally and in BC. We gathered 27 sediment cores over three bays, as close to 1 m in depth as possible, both inter-and sub-tidally. We measured C concentration, stock, and accumulation rates with depth and compared values to bulk density, grain size, stem density, canopy height, and elevation. Results from our study show lower Corg concentration (overall mean = 0.38% C by mass, SE=0.02, range=0.11%-1.75%), Corg stock to 30 cm (mean=14.59 Mg ha-1, SE=1.17, range=16.31-49.99.70), and C sequestration rates (mean=31.71 g m2 yr-1, SE=1.75, range=7.51-132.56) than global averages for seagrass systems. Results corroborated with similar studies in the same study area, as well as those in BC. Though highly productive, Z. marina growth habit is different from seagrass species in warmer climes, which may prevent it from holding on to its Corg. These C accounting data, when completed with quantification of GHG emissions rates, may prevent underestimation of area required for mitigation and restoration, and improve the accuracy of global average seagrass blue C estimates.

Session Title

Seagrass Cross-Border Connections: Management

Conference Track

SSE4: Ecosystem Management, Policy, and Protection

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE4-434

Start Date

5-4-2018 4:30 PM

End Date

5-4-2018 4:45 PM

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 5th, 4:30 PM Apr 5th, 4:45 PM

A search for eelgrass blue carbon across Skagit County bays

Seagrass meadows help mitigate climate change by taking up and storing (sequestering) carbon (C), reportedly at rates only surpassed worldwide by salt marsh and mangrove ecosystems. Now that their climate mitigation capacity has earned seagrass ecosystems a place in the Verified Carbon Standard voluntary GHG program, accurate ecosystem C accounting is essential and coastal ecologists are racing to fill current data gaps. Though seagrasses vary in C storage and accumulation greatly across species and geography, the bulk of data included in calculating global averages involves tropical and subtropical seagrasses. We know little regarding C stocks nor sequestration rates for eelgrass (Zostera marina) meadows in the Salish Sea. The intent of two studies in Padilla, Skagit, and Samish Bays was to quantify carbon stocks and sequestration rates and to compare them to studies occurring simultaneously both locally and in BC. We gathered 27 sediment cores over three bays, as close to 1 m in depth as possible, both inter-and sub-tidally. We measured C concentration, stock, and accumulation rates with depth and compared values to bulk density, grain size, stem density, canopy height, and elevation. Results from our study show lower Corg concentration (overall mean = 0.38% C by mass, SE=0.02, range=0.11%-1.75%), Corg stock to 30 cm (mean=14.59 Mg ha-1, SE=1.17, range=16.31-49.99.70), and C sequestration rates (mean=31.71 g m2 yr-1, SE=1.75, range=7.51-132.56) than global averages for seagrass systems. Results corroborated with similar studies in the same study area, as well as those in BC. Though highly productive, Z. marina growth habit is different from seagrass species in warmer climes, which may prevent it from holding on to its Corg. These C accounting data, when completed with quantification of GHG emissions rates, may prevent underestimation of area required for mitigation and restoration, and improve the accuracy of global average seagrass blue C estimates.