Tidal Elevations and Habitat Change Elkhorn Slough Case Study Photo: Tupper Ansel Blake

Salt marsh loss

1853

1870s

1909

1931

1937 “And such must be the fate of every California River the mouth of which has not sloughroom enough to take in at high tide a volume of water sufficient to clear in its outflow the Bar made by the incoming current.” - U.S. Surveyor General for California (1879)

“The channel recently dredged to the sea at Moss Landing by the Army Corps of United States engineers with federal money gradually is bringing the Elkhorn slough back to its former status of depth and navigability. The natural flow of tidal waters is washing the silt of the past 65 years far out to sea on the outgoing tides.” - Albert Vierra (1958) 1946

Marsh elevation relative to the tides is somewhat self-regulating, but when the rise in relative sea level outpaces a marsh’s maximum sustainable rate of accretion, the marsh gradually submerges until it can no longer sustain vegetation and becomes mudflat, a fate referred to as “ecological drowning. French 1993 Earth Surface Processes and Landforms

Crampton, 1994

Lowe, 1999

Vaage, 1980 Miller and Kvitek, 2004

Photo: Paul Zeretsky