Estuarine, intertidal, mixed fine, partly enclosed, eulittoral

These habitats occur in waters with low wave energy. They consist of mixed sand and mud with small amounts of gravel or with some clay and peat on the upper shore. 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.