Balanced Sediment Fluxes in Southern California’s Mediterranean-Climate Zone Salt Marshes

Jordan A. Rosencranz, Neil K. Ganju, Richard F. Ambrose, Sandra M. Brosnahan, Patrick J. Dickhudt, Glenn R. Guntenspergen, Glen M. MacDonald, John Y. Takekawa, Karen M. Thorne

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterranean-climate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes within a highly modified, sediment-starved, 1.5-km2 salt marsh (Seal Beach) and a less modified 1-km2 marsh (Mugu) with fluvial sediment supply. We measured salt marsh plain suspended sediment concentration and vertical accretion using single stage samplers and marker horizons. At Seal Beach, a 2014 storm yielded 39 and 28 g/s mean sediment fluxes and imported 12,000 and 8800 kg in a western and eastern channel. Western channel storm imports offset 8700 kg exported during 2 months of dry weather, while eastern channel storm imports augmented 9200 kg imported during dry weather. During the storm at Mugu, suspended sediment concentrations on the marsh plain increased by a factor of four; accretion was 1–2 mm near creek levees. An exceptionally high tide sequence yielded 4.4 g/s mean sediment flux, importing 1700 kg: 20 % of Mugu’s dry weather fluxes. Overall, low sediment fluxes were observed, suggesting that these salt marshes are geomorphically stable during dry weather conditions. Results suggest storms and high lunar tides may play large roles, importing sediment and maintaining dry weather sediment flux balances for southern California salt marshes. However, under future climate change and sea level rise scenarios, results suggest that balanced sediment fluxes lead to marsh elevational instability based on estimated mineral sediment deficits.

Original languageEnglish (US)
Pages (from-to)1035-1049
Number of pages15
JournalEstuaries and Coasts
Issue number4
StatePublished - Jul 1 2016

Bibliographical note

Funding Information:
Acknowledgments The authors thank Tristan Edgarian, Chase Freeman, Arianna Goodman, Jimmie Lambert, Katharine Lovett, Katherine Powelson, and Yareli Sanchez for their technical expertise and field assistance. We would like to thank Region 8 US Fish & Wildlife Service Inventory and Monitoring Program, the Southwest Climate Science Center, US Geological Survey (USGS) Western Ecological Research Center, USGS Coastal and Marine Geology Program, and USGS Climate and Land Use Research and Development Program for funding support. The authors would like to thank Andy Yuen and Kirk Gilligan, representing Seal Beach National Wildlife Refuge, Region 8 US Fish & Wildlife Service Refuges for access and field support. We also would like to thank Martin Ruane from Naval Base Ventura County Point Mugu for access and permission to conduct study.


  • Mediterranean climate
  • Salt marshes
  • Suspended sediment fluxes
  • Tidal creeks
  • Vertical accretion

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