They may burrow into the sediment or crawl about on the sediment surface. The group includes worms, crabs, and clams. Some fish are bottom dwellers and may be considered benthic organisms. Click here to go to a web site on San Francisco Bay Ecology created by the Marine Science Institute, located in Redwood City along the shores of the South Bay. The ecosystem in San Francisco Bay no longer resembles the one that existed 150 years ago, before large numbers of people began to settle the region.
Many species are now extinct and many more have been introduced from other locations.
Continuous long-term investigation of San Francisco Bay has given the USGS a rare opportunity to measure ecosystem changes following invasion by a highly successful exotic species. The Asiatic clam, Potamocorbula , was introduced to the Bay in 1986, probably by a cargo ship. A cascading sequence of ecological changes followed, similar to changes in the Great Lakes after their invasion by the zebra mussel. These fundamental ecological changes have likely contributed to the population declines of almost every fish species living in the North Bay. Data are from a USGS web site on Managing Coastal Resources of the U.S. 8.