, Volume 12, Issue 3, pp 147–156

Accretion rates of low intertidal salt marshes in the Pacific Northwest

  • Ronald M. Thom


Salt-marsh accretion rate was investigated at sites that spanned a gradient in relative rate of sealevel rise in Washington and Oregon. Mean accretion rate over all sites was 3.6 mm yr−1 (95% CI=2.4 to 4.8 mm yr1), which exceeded present mean sea-level-rise rate (1.3 mm yr1; sd=0.6). However, a mean rise rate of 5.5 mm yr−1 (sd=1.9) predicted by a moderate sea-level-change scenario to occur by the year 2050 exceeds mean accretion rate. Marshes with adequate sediment input seemed to have the capacity to keep pace with an increased sea-level-rise rate. Lowest accretion rates were recorded at sites with the least sediment supply. Accretion rate showed a weak negative correlation with sediment organic matter (measured as volatile solids) and marsh standing stock. The data suggest that moderate and high rise-rate scenarios would threaten the existence of salt marshes in the region in the absence of increased sediment supply. A better understanding is required of marsh accretion and predicted rate of sea-level rise to refine predictions of the effects of sea-level rise on Pacific Northwest salt marshes.

Key Words

Sea-level rise salt-marsh accretion Pacific Northwest global climate change 


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Literature Cited

  1. Armentano, T.V. and G.M. Woodwell. 1975. Sedimentation rates in a Long Island marsh determined by210Pb dating. Limnology and Oceanography 20:452–456.Google Scholar
  2. Atwater, B.F. 1987. Evidence for great holocene earthquakes along the outer coast of Washington state. Science 236:942–944.PubMedCrossRefGoogle Scholar
  3. Beale, H. 1991. Relative rise in sea-level during the past 5000 years at six salt marshes in northern Puget Sound, Washington. Report Prepared for Shorelands and Coastal Zone Management Program, Washington Department of Ecology, Olympia, WA, USA.Google Scholar
  4. Britsch, L.D. and E.B. Kemp III. 1990 Land loss rates: Mississippi River deltaic plain, US Army Engineer District, New Orleans, Louisiana, Technical Report GL-90-2Google Scholar
  5. DeLaune, R.D., W.H. Patrick, Jr., and R.J. Buresh. 1978. Sedimentation rates determined by137Cs dating in a rapidly accreting salt marsh. Nature 275:532–533.CrossRefGoogle Scholar
  6. DeLaune, R.D., R.H. Baumann, and J.G. Gosselink. 1983. Relationships among vertical accretion, coastal submergence and erosion in a Louisiana Gulf Coast marsh. Journal of Sedimentary Petrology 53:147–157.Google Scholar
  7. Edgerton, L.T. 1991. The Rising Tide. Island Press. Washington, DC, USA.Google Scholar
  8. Frenkel, R.E. and J.C. Morian. 1990. Restoration of the Salmon River salt marshes: retrospective and prospect. Final Report to the U.S. Environmental Protection Agency, Seattle. WA, USA.Google Scholar
  9. Gornitz, V., S. Lebedoff, and J. Hansen. 1982. Global sea level trend in the past century. Science 215:1611–1614.PubMedCrossRefGoogle Scholar
  10. Hatton, R.S., R.D. DeLaune, and W.H. Patrick, Jr., 1983. Sedimentation, accretion, and subsidence in marshes of Barataria Basin, Louisiana. Limnology and Oceanography 28:494–502.CrossRefGoogle Scholar
  11. Kehoe, D.M. 1982. Sources of sediment to Grays Harbor estuary. Grays Harbor and Chebalis River Improvements to Navigation Studies, Seattle District, U.S. Army Corps of Engineers, Seattle, WA, USA.Google Scholar
  12. Knaus, R.M. and D.L. Van Gent. 1989. Accretion and canal impacts in a rapidly subsiding wetland. III A new soil horizon marker method for measuring recent accretion. Estuaries 12:269–283.CrossRefGoogle Scholar
  13. Lynch, J.C., J.R. Meriwether, B.A. McKee, F. Vera-Herrera, and R.R. Twilley. 1989. Recent accretion in Mangrove ecosystems based on137Cs and210Pb. Estuaries 12:284–299.CrossRefGoogle Scholar
  14. Morris, J.T., B. Kjerfve, and J.M. Dean. 1990. Dependence of estuarine productivity on anomalies in mean sea level. Limnology and Oceanography 35:926–930.Google Scholar
  15. Nyman, J.A., R.D. DeLaune, and W.H. Patrick, Jr: 1990. Wetland soil formation in the rapidly subsiding Mississippi River deltale plain: mineral and organic matter relationships. Estuarine, Coastal and Shelf Science 31:57–69.CrossRefGoogle Scholar
  16. Patrick, Jr., W.H. and R.D. DeLaune. 1990. Subsidence, accretion, and sea level rise in south San Francisco Bay marshes. Limnology and Oceanography 35:1389–1395.Google Scholar
  17. Peltier, W.R. and A.M. Tunsingham. 1989. Global sea level rise and the greenhouse effect: might they be connected? Science244: 806–810.PubMedCrossRefGoogle Scholar
  18. Shipman, H. 1990. Vertical land movement in coastal Washington. Washington Geologic Newsletter 18:26–33.Google Scholar
  19. Stoddart, D.R., D.J. Reed, and J.R. French. 1989. Understanding salt-marsh accretion, Scoly Head Island, Norfolk, England. Estuaries 12:228–236.CrossRefGoogle Scholar
  20. Thom, R.M. 1981. Primary productivity and carbon input to Grays Harbor estuary, Washington. Grays Harbor and Chehalis River Improvements to Navigation Studies, Seattle District, U.S. Army Corps of Engineers, Seattle, WA, USA.Google Scholar
  21. Thom, R.M., C.A. Simenstad, J.R. Cordell, D.K. Shreffler, and L. Hamilton. 1990. The Lincoln Avenue wetland system in the Puyallup River estuary, Washington. Phase IV report: year four monitoring, January–December 1989. Fisheries Research Institute, FRI-UW-9004, University of Washington, Seattle, WA, USAGoogle Scholar
  22. U.S. Department of Commerce. 1990. Tide tables 1991 west coast of North and South America. National Ocean Service, Rockville, MD, USA.Google Scholar
  23. Wood, M.E., J.T. Kelley, and D.F. Belknap. 1989. Patterns of sediment accumulation in the tidal marshes of Maine. Estuaries 12: 237–246.CrossRefGoogle Scholar

Copyright information

© Society of Wetland Scientists 1992

Authors and Affiliations

  • Ronald M. Thom
    • 1
  1. 1.Battellel Marine Sciences LaboratorySequim

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