California coast ecosystems are the habitats that exist within narrow bands by the land-sea interface. California has around 1,100 miles of open coast that meet the Pacific Ocean. Dominant habitats along the coast are marshes, mudflats, rocky shores, estuaries, and beaches. Such habitats provide critical roles as nurseries and migration rest stops for a great diversity of both marine and terrestrial species. California’s coastal ecosystems have the highest amount of native species richness in the state.

California’s coastal ecosystems are characterized by temperate climates and coastal fog. Coastal fog is a marine cloud layer that provides moisture to the coast and is vital to the coastal communities especially in warm summer months. Some habitats found only along the coastal margin are rocky intertidal habitats, upper beaches, and regularly-flooded estuarine marshes.