Larry Serpa

California Freshwater shrimp in the Lagunitas watershed

More than 24 miles of ocean and bay border Golden Gate. Coastal and bay resources comprise biologically diverse and complex ecosystems, which contain a rich array of marine invertebrates and algae. Intertidal communities within or adjacent to park boundaries include natural islands, reefs, offshore rocks, straits, lagoons, mudflats, and beaches. Man-made habitat include piers, wharves, and shoreline rubble. The Gulf of the Farallones Marine Sanctuary is just offshore, and the San Francisco Bay-Estuary empties through the straits of the Golden Gate. Slide Ranch, Muir Beach, Pirates Cove, Kirby Cove, Fort Point, and Alcatraz display a rich diversity of sponges, bryozoans, tunicates, limpets, mussels, anemones, and sea stars on their rocky headlands. Barnacles and isopods cover the splash zone. Sea caves abound in the park and have yet to be inventoried.

At Rodeo Beach Bird Rock (a guano-covered sea stack), marine invertebrates include large chilipepper shrimp, California mussels, and green anemone and purple seastars. Less common invertebrates include abalone and sea urchins. Rocky intertidal areas are interspersed throughout Marin County at Stinson Beach, Slide Ranch, Muir Beach, Tennessee Cove, Rodeo Beach, Bonita Cove, Kirby Cove, and Lime Point. The intertidal zone along the coast of Marin County is generally steep and rocky, with small beaches occurring adjacent to watershed drainage areas, and not easily accessible by the public. In San Francisco County intertidal areas are primarily beach or pier habitat including Fort Funston, Ocean Beach, Land’s End, China Beach, Baker Beach, Fort Point, Crissy Field, Fort Mason, Black Point, and Aquatic Park. Many of the intertidal areas serve as living outdoor classrooms for Bay Area residents and visitors. The state‑protected Dungeness crab breeds in the Pacific Ocean just offshore, and many Dungeness juveniles, as well as other species of shore crabs, can be spied in the park's rocky areas and mud flats

The California freshwater shrimp is endemic to Marin, Sonoma and Napa counties, but only remains in portions of 16 coastal streams. Lagunitas Creek in Marin County contains the most viable population of the shrimp and it is the only site occurring on protected lands. The shrimp is threatened by water diversions on Lagunitas Creek, watershed erosion, stream sedimentation, riparian vegetation removal, agricultural development, grazing, and urbanization.