CBRISC:  background



Changes in the Southern California Rocky Intertidal

Many observations suggest that human activities have caused changes in Southern California rocky intertidal communities over the past century.

"Whites Point was at one time noted for its Haliotis cracherodii [black abalone], but continuous collecting has almost despoiled it of these shells." -- Mrs. M. Burton Williamson. 1892. An annotated list of the shells of San Pedro Bay and Vicinity.

“Collectors who have collected from Mission Bay for years report the entire disappearance of certain forms from the regions wherein they had previously found them common.” -- R. Morrison. 1928. A study of molluscs found at Mission Bay San Diego, California.

“The gigantic horse mussel . . . up to 9 inches in length, is no longer common, its depletion being the result, probably, of too many chowders, too many conchologists, and the animal’s presumably slow rate of growth.” -- Ricketts et al. 1968. Between Pacific Tides (4th edition).



Population Growth in Southern California

Changes in the intertidal have occured during a period of massive growth in the human population in Southern California.

Increased population pressure has been documented to negatively affect intertidal communities through:

  • pollution
  • harvesting of animals
  • habitat disturbance / trampling
Combined population of San Diego, Orange, Los Angeles, Ventura and Santa Barbara counties (1850-2000).



The CBRISC project uses historical and modern records to document and understand changes in the rocky intertidal of Southern California over the past century.

Next: CBRISC Goals