Estuarine, intertidal, boulder, partly enclosed, eulittoral

Boulder-dominated intertidal areas in estuarine waters occur uncommonly in the Puget Sound; some could be classified as artificial substrata (riprap), while some consist of glacial erratics perched on hardpan.  'Partly enclosed' sites are in embayments with relatively low waves or currents, so that silt may settle on the rock and reduce settlement or survival of small algae and filter-feeders.  The plants and animals seen on these rocky substrata are largely a freshwater-tolerant subset of those seen on protected marine shores. These habitats may be richer than bedrock because of the additi