Substrata in these areas consist of cobbles of varying stability lying over a matrix of sand and gravel. Few complete surveys have been done in this habitat type, but areas examined are quite rich due to the mix of infauna and epibiota.

Common Species

On cobbles, the surfgrass Phyllospadix scouleri (higher energy areas) or Zostera marina (lower energy), along with the brown algae Laminaria spp., Desmarestia spp., Pterygophora californica and others, and foliose reds including Odonthalia spp., plus ulvoids.  Invertebrates in these habitats include the snails Lacuna spp., the bivalves Modiolus rectus, Astarte spp., and Saxidomus giganteus, the crabs Cancer productus and C. oregonensis, the polychaetes Glycymeris subobsoleta, Thelepus sp., Platynereis bicanaliculata, the sea cucumbers Cucumaria spp., the tanaid crustacean Leptochelia savignyi, and the amphipods Pontogeneia sp. and others. These habitats are probably used by similar fish and diving birds as are intertidal mixed-coarse areas.

Sites Surveyed

Partridge Point and Ebey’s Landing (Whidbey Island), Buck Bay (Orcas Island), Lonesome Cove (San Juan Island).

Sources

Webber, 1980 and unpubl. data; G.F. Smith, 1979; Irvine, 1973.