Temporary Closure of Waters Around Alcatraz Island
From 7/3 to 9/22 a 500’ marine buffer zone is in effect, closing the perimeter of Alcatraz Island to all private vessels to protect nesting seabirds during America's Cup racing. Tours to Alcatraz continue as usual during the races. More »
Muir Beach (but not nearby Muir Woods) closed July 8-November 2013, but local businesses are open
Though Muir Beach is closed from July 8-November 2013 due to construction, the PELICAN INN IS OPEN. Restrooms and parking are not available at Muir Beach. Pacific Way is closed except to residents. Check back for updates or call (415)561-3054. More »
CAUTION: Post Storm Damage to Coastal Trail
The Presidio Coastal Trail segment just north of the Pacific Overlook and adjacent to Lincoln Blvd remains CLOSED indefinitely. We have posted signage to alert bicyclists and hikers and with information for safe trail alternatives. More »
Wetlands, Marshes and Swamps
Estuaries provide transition from ocean to land. Freshwater streams meet saltwater tides creating one of the most fertile habitats on earth. Fast growing marsh vegetation provide habitat for decomposers, and the food system is based on detritus (decomposed plant materials) rather than live plants. Estuaries also act as a doorway for ocean fish who spawn in freshwater streams such as Coho salmon and steelhead trout. For other fish and crabs, estuaries are the perfect place to spawn, leaving the juveniles in the protection of the vegetation and abundant food supply to grow up until they are ready to enter the open ocean. Estuaries also provide important stopovers for migrating ducks and shorebirds as they fly thousands of miles up and down the Pacific Flyway.
The life of marshes is determined by the tides that wash in and out twice daily. They are either submerged by salty water or left high and dry as the tides recede. Marsh organisms are distributed at different tidal levels, depending on their ability to withstand the stress of tidal inundation. Eelgrass beds grow in channel bottoms and deep basins, supporting sponges, tunicates, and moss animals. Most of these animals are filter feeders or graze on microscopic algae that grow on the leaves of the eel grass. In the mudflats (shallow areas where little vegetation grows), are worms, clams, and snails. Most of these animals are detritivores, filtering organic particles from the water like crabs and shrimp. Raccoons and fox also regularly come down to water’s edge looking for a snack.
The threatened Point Reyes bird's beak ranges along the central California coast, but due to widescale development of marshlands, numbers have quickly dropped. This small annual was introduced to the recreated salt marsh at Crissy Field in 2001.
The endangered California sea blite, although once abundant from Morro Bay up the central California coast, has been extirpated from San Francisco Bay. This small succulent shrub was also introduced to the recreated salt marsh at Crissy Field in 2001. It has since done poorly and reintroduction status is being considered.
Did You Know?
By the 1850s, Fort Mason was established as a military installation and the buildings on Franklin Street, constructed between 1864 and 1913, are some of the earliest remaining buildings at Fort Mason.