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Wetlands

Salt Marshes and Brackish Marshes

Salt marsh, Nehalem Bay, Tillamook County

Salt marsh, Nehalem Bay, Tillamook County
(John A. Christy, Oregon Biodiversity Information Center)

Salt marshes and brackish marshes occur in the intertidal zone of coastal estuaries. They are dominated by salt-tolerant herbaceous plants and are usually intermixed with intertidal mudflats that are rich with invertebrates and seaweeds. Farther inland in an estuary, salinity becomes diluted by fresh water from rivers and streams, and a gradual transition to freshwater plants and animals occurs, and woody vegetation becomes more evident. The Cowardin Classification identifies the transition from Estuarine to Riverine and Palustrine systems at points where salinity drops to less than 0.5 parts per thousand (ppt). This transition zone is a moving target in upper estuaries, and is influenced by seasonal or episodic river flows and fluctuations in daily tidal cycles. With the anticipated rise in sea level associated with global climate change, many salt and brackish marshes may become permanently inundated, and their landward edges will advance into what are currently freshwater marshes, shrub swamps, and uplands. The estuarine-freshwater transition zone will also migrate upriver with rising sea level.

Salt Marsh Map

Salt Marsh Map


Habitat: Edges of estuaries, tidal rivers, and tidal streams
Water regime: Subtidal, tidal, regularly to irregularly flooded
Water chemistry: Saline to brackish

Ecoregion*: BM = Blue Mountains, BR = Northern Basin and Range, CB = Columbia Basin, CR = Coast Range, EC = East Cascades, KM = Klamath Mountains, WC = West Cascades, WV = Willamette Valley  
Scientific & Common Name Global & State Rank Ecoregion*
wetland type image Argentina egedii - Juncus balticus Herbaceous Vegetation
Pacific silverweed - Baltic rush
G3S2 CR
wetland type image Argentina egedii - Symphyotrichum subspicatum Herbaceous Vegetation
Pacific silverweed - Douglas aster
G3S2 CR
wetland type image Carex lyngbyei Herbaceous Vegetation
Lyngby sedge
G4S3 CR
wetland type image Carex lyngbyei - Argentina egedii Herbaceous Vegetation
Lyngby sedge - Pacific silverweed
G4S2 CR
wetland type image Carex lyngbyei - (Distichlis spicata, Triglochin maritima) Herbaceous Vegetation
Lyngby sedge - (saltgrass, arrow grass)
G4S2 CR
wetland type image Deschampsia caespitosa - Argentina egedii Herbaceous Vegetation
Tufted hairgrass - Pacific silverweed
G3S2 CR
wetland type image Deschampsia caespitosa - Juncus balticus Herbaceous Vegetation [Provisional]
Tufted hairgrass - Baltic rush
G4S2 CR
wetland type image Distichlis spicata - (Sarcocornia perennis) Herbaceous Vegetation
Saltgrass - glasswort salt marsh
G4S2 CR
wetland type image Juncus balticus - Carex obnupta Herbaceous Vegetation [Provisional]
Baltic rush - slough sedge
G4S4 CR
wetland type image Juncus falcatus - Trifolium wormskjoldii Herbaceous Vegetation
Sickle-leaved rush - springbank clover
G4S3 CR
wetland type image Ruppia (cirrhosa, maritima) Permanently Flooded Herbaceous Vegetation
(Spiral ditch-grass, beaked ditch-grass)
G2S2 CR
wetland type image Schoenoplectus acutus Herbaceous Vegetation
Hardstem bulrush
G5S5 CR
wetland type image Schoenoplectus maritimus Herbaceous Vegetation [Provisional]
Seacoast bulrush
G3S2 CR
wetland type image Triglochin maritima - (Sarcocornia perennis) Herbaceous Vegetation
Arrow grass - (glasswort)
G4S2 CR
wetland type image Zostera marina Herbaceous Vegetation [Provisional]
Eelgrass
G5S3 CR

Authored by John A. Christy, Wetlands Ecologist, (ORBIC) Oregon Biodiversity Information Center (2012)

randomness