Marine, intertidal, bedrock, protected, eulittoral

Many areas in the northern Puget Trough receive neither oceanic swell nor extensive wind fetch, but retain their rocky character due to steepness of the shore or currents that sweep away most sediment. Examples are the inside waters of the San Juan Islands, where there is not enough freshwater input for sites to be categorized as Estuarine. Siltation, desiccation, and temperature stresses all take their toll on rocky-shore organisms in these areas, and diversity is correspondingly low relative to more wave-exposed coastal sites.