The rocky intertidal zone, or the band of rocky shore covered up by the highest of tides and exposed by the lowest of tides, is an extraordinarily diverse and productive ecosystem. More than 1,000 species of invertebrates and algae live in Central California's rocky intertidal areas, and many more fish, birds and mammals rely on rocky intertidal species as a source of food. While rocky intertidal communities can withstand pounding surf and scorching sun, they are also highly sensitive to pollution, oil spills, invasive species and changing air and ocean temperatures.
The San Francisco Bay Area Inventory and Monitoring Program monitors rocky intertidal communities at five sites in Golden Gate National Recreation Area and Point Reyes National Seashore. Though rocky intertidal monitoring has taken place at some sites since 1989, a new monitoring protocol developed for the Multi-Agency Rocky Intertidal Network (MARINe) was adopted in 2006 to allow results to be directly compared to more than 100 other MARINe sites.