Estuarine Intertidal Mixed-Coarse: Open

Most open estuarine intertidal sites in the Puget Trough have a poorly sorted substratum of mixed cobble, gravel, and sand, often distributed in patches along the beach.  Some small boulders, which are relatively stable, often overlie other substrata.  Organisms in these habitats are diverse, with both epifauna and infauna.  Eelgrass beds often lie just subtidally of these beaches where the substratum becomes less coarse.  These beaches are used as feeding areas by cutthroat trout, juvenile salmon (chum and pink), fish-eating birds such as cormorants, grebes, loons, mergansers, and great blue herons, and bivalve-eating birds such as scoters and goldeneyes.

Diagnostic Species

Green ulvoid algae, the clams Macoma inquinata (especially on more exposed beaches) and Protothaca staminea (less exposed), the phoronid worm Phoronopsis harmeri, the polychaetes Owenia fusiformis, Mediomastus capensis and Notomastus tenuis.

Common Associates

The clams Saxidomus giganteus, Tresus capax, Transennella tantilla, Mysella tumida, and Tapes philippinarum; the polychaetes Hemipodus borealis, Protodorvillea gracilis, Nereis spp. and Malacoceros glutaeus; the amphipod Corophium brevis, the crabs Hemigrapsus nudus, Cancer productus, Petrolisthes eriomerus and Pagurus spp.; the algae Fucus gardneri, Mastocarpus papillatus, Iridaea splendens, Pterosiphonia bipinnata, Odonthalia floccosa, Alaria marginata, and Porphyra spp.; the epifauna Mytilus edulis, oysters, limpets, Littorina spp., Anthopleura elegantissima, A. artemisia, Urticina coriacea, and Balanus glandula, and the predators

Leptasterias hexactis, Evasterias troschellii, and Nucella lamellosa.  Fish include the blennies Anoplarchus purpurescens and Xiphister mucosus, penpoint gunnels, northern clingfish, shiner perch, surf smelt, C-O sole, and three-spined stickleback.  Herring spawn on vegetation in cobbly areas.

Sites Surveyed

In central Puget Sound—Richmond Beach, Carkeek Park, West Point, West Beach, Alki Point, Lincoln Park Beach, Salt Water State Park, Covenant Beach, Redondo Beach, Seahurst, Seola, Normandy Cove. On Vashon Island—Point Robinson, Tramp Harbor, Aquarium, and Fern Cove.  In Hood Canal— Anderson Cove.  In northern waters—Port Gardner, Kiket Island, Skiff Point, Cherry Point/ Birch Bay, Migley Point (Lummi Isl.), Shannon Point, and Point Washington Narrows.


Houghton, 1973; Shimek, 1977; Armstrong et al., 1976; Thom et al., 1976; Thom et al., 1979; Staude, 1979; Nyblade, 1979a,b; Webber, 1980; Smith and Webber, 1978; Thom et al., 1984; Chew, 1970; Sylvester and Clogston, 1961; Roetcisoender and English, 1976.