Marine, intertidal, mixed coarse, partially exposed, eulittoral

Mixed-coarse sediments are those where no one grain size occupies more than 70 percent of a stretch of beach. Instead, the beach is a mix (in variable quantities) of a few boulders, with cobble, gravel, and sand. Such sites often exist where sea stacks or other features reduce the wave energy reaching the shore. These habitats usually have very high species diversity because of the range of microhabitats they provide: stable tops of cobbles, undersides of cobbles, among loose sediment, and within the stable sediment beneath the cobbles. Clams often thrive in this sediment because it is hard for predators to dig to them. Drift algae may accumulate in these habitats, providing additional food and habitat for a variety of organisms.

Habitat attributes

Class ID: 
Class name: 
Marine, intertidal, mixed coarse, partially exposed, eulittoral
75.0 km (in WA)
Primary substrate: 
Secondary substrate: 
Tertiary substrate: 
Substrate stability: 
Semi-stable surface features
Substrate key details: 
Cobble, pebble, sand (some stable surface features)
Wave exposure: 
Blue book classes: 
Marine intertidal mixed-coarse: Semi-protected to Protected
Map/survey site examples: 
Much of northern Olympic coast; Most of western Whidbey Is, Partridge Point (in part), False Bay (in part)
Fish sampling sites: 
Beach Seine: West Beach
Diagnostic species: 
  • Fucus distichus
  • Mytilus trossulus
  • Leukoma staminea
  • Ulva spp.
  • Mastocarpus
  • Macoma inquinata
  • Balanidae
  • Lottia
  • Platichthys stellatus
  • Parophrys vetulus
  • Psettichthys melanostictus
  • Cymatogaster aggregata
VEC common associates: 
Venerupis philippinarum
Saxidomus gigantea
Tresus capax
Species notes: