Estuarine, intertidal, mixed fine, open, eulittoral

These habitats occur on beaches with some wave energy or on deltas away from large distributary channels. They consist of mixed sand and mud with small amounts of gravel. The substratum is generally stable, firm, and organic-rich. Productivity is high due to eelgrass, micro- and macro-algae, and salt marsh vegetation. Drift algae and seagrass may be abundant seasonally. Areas with gravel may have hard-shelled clams. Detritivores in the sediment are very dense, and are preyed upon by other invertebrates as well as by numerous birds and fishes. The amphipod Corophium provides a major food resource for numerous fish and shorebirds. Because of the presence of eelgrass (which reaches its highest densities in muddy sand) and marsh grasses, these habitats are used by a variety of birds: great blue herons, mergansers, western grebes, and brant. Areas without eelgrass are much less diverse, although crows, gulls, killdeer, great blue herons, mallards, and pintails forage in muddy sand. Raccoons, deer, skunks, and weasels forage on these shores.

Habitat attributes

Class ID: 
Class name: 
Estuarine, intertidal, mixed fine, open, eulittoral
15.0 km (in WA)
Primary substrate: 
Secondary substrate: 
Tertiary substrate: 
Substrate stability: 
Substrate key details: 
Few stable surface features
Wave exposure: 
Semi-protected, Protected
Blue book classes: 
Estuarine intertidal mixed-fines: partly enclosed
Map/survey site examples: 
Mouth of Nooksack River
Fish sampling sites: 
Diagnostic species: 
  • Zostera marina
  • Leukoma staminea
  • Saxidomus gigantea
  • Neotrypaea californiensis
  • Ulva spp.
  • Macoma balthica
  • Hypomesus pretiosus
  • Parophrys vetulus
  • Gasterosteus aculeatus
  • Platichthys stellatus
VEC common associates: 
Crassostrea gigas
Cancer spp.
Mya arenaria
Species notes: