Coastal Geomorphologist
Controls on sediment accretion and blue carbon burial in tidal saline wetlands: Insights from the Oregon coast, USA
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.
Products:
Peck, E. K., Wheatcroft, R. A., & Brophy, L. S. (2020). Controls on sediment accretion and blue carbon burial in tidal saline wetlands: Insights from the Oregon coast, USA. Journal of Geophysical Research: Biogeosciences, 125(2), e2019JG005464. https://doi.org/10.1029/2019JG005464
Data: doi.org/10.25573/serc.11317820
Related Conference Abstracts:
AGU Fall Meeting, Washington, DC (eLightning Presentation, December 2018) "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 (Poster, October 2018) "Changing sediment and blue carbon accumulation recorded in Oregon salt marshes"
AGU Fall Meeting, San Francisco, CA (Poster, December 2016) "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)"
CERF 23rd Biennial Conference, Portland, OR (Poster, November 2015) "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
Funding: Research was funded by Oregon Sea Grant [project # NA14OAR4170064; R/HBT-21-Wheatcroft]