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Improved understanding of sediment dynamics and direct management applications for the South Slough National Estuarine Research Reserve and the greater Coos Bay Estuary (NOAA NERRS)

Emily and Tyler are working with Dave Sutherland (UO), Molly Keogh (UO), Dave Ralston (WHOI), and colleagues at the South Slough National Estuarine Research Reserve to evaluate sediment transport pathways and habitat impacts for eelgrass and oysters in Coos Bay Estuary, Oregon. Coos Bay is a regionally important estuary, offering one of the largest port facilities between Puget Sound and San Francisco Bay as well as diverse ecosystem services. By partnering with Reserve staff and area stakeholders including port operators and engineering consultants, we are working to understand the hydrodynamics and sediment dynamics within the estuary. For further reading on the background of the project see Sutherland & O’Neill, 2016.

Summer 2021 update

At the end of May, Tyler joined a weeklong field expedition to Coos Bay along the Oregon Coast. The research team spent the week wading through waist deep mud to collect a series of cores to provide insight into how sediment dynamics within the estuary have changed over the last 150 years.  Using multiple coring techniques, the team was able to retrieve 24 cores (14 one-meter long cores and 10 ten-centimeter cores) totalling over 150 pounds of sediment! The team was lucky to have multiple days of beautiful weather, a rarity along the Oregon Coast, and only to get stuck in the mud a few times.

The cores that the research team collected will be analyzed in our lab at UNC for radioisotope analysis as well as sediment texture.  The primary focus with the long cores is Pb-210 via alpha detection where the sediment will be stripped of its lead using strong acids and which is then plated onto planchets for use in the alpha detectors.  The Pb-210 isotope decays with a half-life of 23 years and allows us to understand changes in sedimentation up to 150 years ago.  The short cores will be passively analyzed in the gamma detectors to understand changes in sedimentation on a month to month basis in this highly seasonal system. This work will be supported by Daniela Zarate, who joined the lab this summer, and Dr. Brent McKee and Sherif Ghobrial who run the radiochemistry lab.

We hope to use the data generated from this expedition to better understand how the Coos Bay Estuary has changed over the last two centuries in response to human forcing such as dredging and wide-scale logging.  This information will allow us to better understand how sediment transport patterns are affecting species in the estuary, as well as how sediment dynamics are influencing coastal resiliency for the cities along the Oregon coast.

Tyler and the research team are so thankful for all the help we got from folks in Oregon including people with South Slough National Estuarine Research Reserve and the Oregon Institute of Marine Biology.  We could not have been so successful without y’alls’ help!


Recent papers from the Coos Bay project:

Eidam, E.F., Sutherland, D.A., Ralston, D.K., Conroy, T., Dye, B. Shifting sediment dynamics in the Coos Bay Estuary in response to 150 years of modification. JGR-Oceans. Link

Eidam, E.F., Sutherland, D.A., Ralston, D.K., Dye, B., Conroy, T., Schmitt, J., Ruggiero, P. and Wood, J., 2020. Impacts of 150 Years of Shoreline and Bathymetric Change in the Coos Estuary, Oregon, USA. Estuaries and Coasts, pp.1-19. Link

Conroy, T., Sutherland, D.A. and Ralston, D.K., 2020. Estuarine exchange flow variability in a seasonal, segmented estuary. Journal of Physical Oceanography, 50(3), pp.595-613. Link


Vegetated saltmarshes in upper Coos Bay Estuary