Many of the park's marine bird species are migratory. Brown pelicans are summer visitors, cormorants take to lagoon or river and shore waters, and willets and sanderlings work the beach. In the intertidal areas the vagaries of periodic wetting and drying have produced tightly zoned layers of life. Lagoons where fresh water and salt water mix are extremely productive of sea life. Offshore Between shore and the deep ocean an average surface acre is as productive as a similar acre of fertilized agricultural land.
Basic wealth lies in phytoplankton, single-celled plants.
Sea lions feed beyond the surf and haul out on shore or on sea stacks. Several kinds of sea birds nest on offshore rocks. Intertidal Zone Twice daily on a 25-hour lunar cycle, tides rise and fall. In the zone between high and low tide, life forms arrange themselves vertically. A splash zone just above high tide is home for periwinkle snails and beach hoppers that can withstand the powerful shock of pounding waves and episodic wetting.