Controls on Sediment Accretion and Blue Carbon Burial in Tidal Saline Wetlands: Insights from the Oregon Coast, USA


Published in 2020 in JGR-Biogeosciences 

Co-Authors: Robert A. Wheatcroft & Laura S. Brophy

Abstract: Oregon estuaries provide important opportunities to assess controls on tidal saline wetland carbon burial and sediment accretion as both rates of relative sea level rise (RSLR; −1.4 ± 0.9 to 2.8 ± 0.8 mm yr−1) and fluvial suspended sediment load relative to estuary area (0.23 to 17 × 103 t km−2 yr−1) vary along the coast. We hypothesized that vertical accretion, measured using excess 210Pb in least‐disturbed wetlands within seven Oregon estuaries, would vary with either RSLR or sediment load relative to estuary area, and carbon burial would correlate strongly to sediment accretion. Mean rates of high marsh accretion (0.8 ± 0.2 to 4.1 ± 0.2 mm yr−1) indicate that Oregon tidal wetlands have mainly kept pace with twentieth‐century RSLR with the exception that the accretionary balance in the central coast is negative, suggesting drowning. Experiencing the fastest rates of RSLR, central‐coast estuaries may foreshadow the fates of other Oregon estuaries under future accelerated sea level rise. Comparison of mass accumulation rates with sediment loads, however, indicates low trapping efficiency and therefore no fluvial sediment limitation. Thus, nonlinear feedback between RSLR and sediment accretion may enhance wetland resistance to drowning. Among wetlands keeping pace with or exceeding RSLR, sediment accretion displays no significant relationship with elevation but rather appears controlled by both the rate of RSLR and relative sediment load, highlighting the importance of incorporating both factors into future studies of tidal saline wetlands. Carbon burial rates, controlled by sediment accretion, will likely increase with future accelerated sea level rise.

Funding: ​Oregon Sea Grant Omnibus Grant


Read the Publication

Read my MS thesis: Competing Roles of Sea Level Rise and Sediment Supply on Sediment Accretion and Carbon Burial in Tidal Wetlands; Northern Oregon, USA


Related Conference Abstracts:


AGU Fall Meeting, Washington, DC (December 2018)

Erin Peck, Rob Wheatcroft, & Laura Brophy

eLightning Presentation – Controls on sediment accretion and blue carbon burial in salt marshes: Insights from the Oregon coast (Abstract ID: #EP51B-20)

State of the Coast, Coos Bay, OR (October 2018)

Erin Peck, Rob Wheatcroft, & Laura Brophy

Poster – Changing sediment and blue carbon accumulation recorded in Oregon salt marshes

AGU Fall Meeting, San Francisco, CA (December 2016)

Erin Peck, Rob Wheatcroft, & Laura Brophy

Poster - Influence of sea level rise on tidal wetland sediment and carbon accumulation under differing fluvial sediment supply in the Pacific Northwest (Abstract ID: EP21B-0880)

AGU Fall Meeting, San Francisco, CA (December 2016)

Grace Molino, Rob Wheatcroft, Erin Peck, & Laura Brophy

Poster - Natural and anthropogenic causes of accelerated sediment accumulation rates in Nehalem Bay salt marshes, Oregon (Abstract ID: #EP21B-0881)

CERF 23rd Biennial Conference, Portland, OR (November 2015)

Erin Peck, Rob Wheatcroft, & Laura Brophy

Poster - Quantifying sediment and carbon accumulation in Oregon tidal wetlands (Abstract ID: 0480-000886)

In the News: 

Oregon Sea Grant Confluence (01/30/19) "6 Oregon Salt Marshes Have Stayed Ahead of Rising Sea, Study Says" by Tiffany Woods

OSU College of Earth, Ocean, & Atmospheric Sciences Features (04/10/18) "Deep Blue: Rob Wheatcroft and Erin Peck Explore Blue Carbon in Oregon Salt Marshes" by Nancy Steinberg