Rocky Intertidal



	ROCKY INTERTIDAL areas and areas of mixed rocky and sandy shoreline cover approximately 30% or 20 miles (32 km) of the Bay's coastline. Specifically, rocky intertidal habitat is found intermittently between the Ventura County line and Will Rogers Beach to the north, and in the south along the Palos Verdes Peninsula from Malaga Cove to Point Fermin (Map of rocky intertidal). The rocky intertidal areas are an important interface between the sea and the land, providing habitat for numerous and diverse species in the Bay. Historically, impacts from wastewater discharges had a large impact on rocky intertidal areas in Southern California. One study (Dawson 1959, 1965) noted reductions of 50 to 70% in algal species diversity between 1895-1912 and 1956-59 at sites near the Joint Water Pollution Control Plant sewage outfalls at Whites Point. Later studies showed similar declines. A continuing threat to rocky intertidal habitats and the associated biological communities is direct human disturbance in the form of trampling, rock turning, and collecting by the many visitors to these areas. Two protected areas have been established on the Palos Verdes Peninsula to help save rocky intertidal habitat from these visitor impacts. The two areas, one at Abalone Cove and the other at Point Fermin, are designated as Ecological Reserves by the California Department of Fish and Game. Restrictions in these areas include: no taking or disturbing of any plant or animal; no commercial fishing; no pets without a leash; and no fires. However, without active enforcement, the protection afforded by these areas is limited. Another source of concern is the rapid decline of black abalone, a rocky intertidal species. Although the cause of the decline is not completely understood, researchers have speculated that a combination of overharvesting, predation, competition, environmental changes, and disease may be responsible. Due to the rapid decline in black abalone and other abalone species in Southern California since 1993, it has been illegal to take, possess, or land any abalone south of San Francisco Bay. The SMBRC is supporting research to survey rocky intertidal habitat in the Bay and determine visitor impacts to intertidal communities. Additionally, scientists from federal, state, and local government agencies; university researchers; and volunteer organizations have formed a Multi-Agency Rocky Intertidal Network (MARINE) in order to monitor important shoreline resources. This network of 61 sites includes two located in Los Angeles County: Paradise Cove & White Point. One of the objectives of this network is to establish consistent monitoring methodologies so that spatial and temporal comparisons can be made in the future. To learn more about rocky intertidal habitat in the Bay, visit our Habitats and Species page. References Dawson, E. Y. 1959. "A primary report on the benthic marine flora of southern California." In: An Oceanographic and Biological Survey of the Continental Shelf Area of Southern California. Publication of the California State Water Quality Control Board 20:169-264. Dawson, E. Y. 1965. "Intertidal algae." In: An Oceanographic and Biological Survey of the Southern California Mainland Shelf. Publication of the California State Water Quality Control Board 27:220-231.