Prior to human development of the area, the coast between Santa Monica and the Palos Verdes Peninsula consisted primarily of sand dunes and sandy beaches that shifted due to the action of air and water currents. The gradual process of urban development has changed the way beaches are created, both because jetties and other man-made structures interfere with the coastal distribution pattern, and because the sediments that once helped replenish beach sands are now held back by dams or diverted into flood control channels and deposited elsewhere on the coast.
Certain species are of particular concern specifically because of the loss or degradation of Southern California beach habitat. These include the endangered California least tern, El Segundo blue butterfly and Western snowy plover.
Projects underway to protect the California least tern include providing protected nesting habitat near suitable foraging areas. Venice Beach has one of the most successful breeding sites in California. The Santa Monica Bay Restoration (SMBRP) has worked with other local agencies to establish a second colony near Playa del Rey.
The El Segundo dunes, habitat for the El Segundo blue butterfly, are a remnant of a once vast coastal ecosystem. Over 900 species of plants and animals have recently been recorded on these dunes, at least 11 of which exist only within its boundaries. Restoration of this unique habitat has begun and plans are underway to establish a Dune Habitat Preserve.
Oil spills are also a potential threat to beach and intertidal habitats, especially to such species as the California grunion, a tiny fish that lays its eggs on sandy beaches.
With intense and increasing human use of the beaches and waters of Santa Monica Bay, both trash and the need for beach clean-up have increased.
Finally, beaches and rocky intertidal habitats are vulnerable to the contaminants often contained in urban runoff. Filter-feeding intertidal organisms have a particularly high potential for bioaccumulating toxic organic compounds. Bioccumulation means that the compounds stay (and acumulate) in their bodies. The susceptibility of intertidal communities can be inferred from the high concentrations of trace metals such as lead and chromium found in the tissues of California mussels near Marina del Rey.