Rocky Intertidal Habitats of the California Central Coast
Habitats worth protecting with National Marine Sanctuary Designation
by Carol Georgi and Karl Kempton
(Former Energy Planner for San Luis Obispo County and
Lead Author of "Proposed Central Coast National Marine Sanctuary, 1990")
Introduction to the Intertidal Zone
The rocky intertidal habitat zone is one of beachgoers favorite places to walk, especially at low tide to view marine life.
Filmed at Brady’s Beach in Barkley Sound, British Columbia
Between the high and low tide lies a strip of shoreline that is regularly covered and uncovered by the advance and retreat of ocean waters. This meeting ground between land and sea is called the intertidal zone.
Along rocky shores, the inhabitants are hardy and adaptable as they are subjected to a variety of harsh conditions. Organisms living in this area must be able to withstand periodic desiccation (drying out), changes in temperature, light and salinity, as well as strong wave action. Variation in the degree of exposure to these environmental factors can create marked zonation within the habitat.
Intertidal Biome AP Biology Project / Photography by Jess Skogh.
The Supralittoral Fringe or Splash Zone
(about 4.7 to 7 feet above sea level)
This zone is the area above the mean high tide level that receives spray from waves. Almost always exposed to air, the supralittoral fringe zone is sparsely vegetated and inhabited by relatively few animals. The rock Louse, Ribbed Limpet, and Black Periwinkle often inhabit this zone.
The Midlittorial Zone
(about 0 to 4.7 feet above sea level)
This zone is the area that is covered and uncovered usually twice each day and where tide pools, abundant with life, are found. A wide variety of algae can be found in this zone. Endocladia, a red alga grows in the low-lying tufts, is often the dominant plant. Other common algae include Porphyra, Mastocarpus, Egregia (Feathered Kelp) and Pelvetia (Rockweed).
In the rougher surf areas, Sea Palms (Polsteria) stand erect against the crashing waves. The invertebrates include mostly sessil species such a California Mussels, Gooseneck Barnacles, and Aggregated Anemones. Turban Snails, Hermit Cabs, Lined Shore Crabs, Purple Crabs and Sea Stars are common in the upper tide pools. Chitons are common on the sides of rocks. Tidepool fish include Striped Surfperch, Tidepool Sculpin, Tidepool Snailfish and Cabezon.
The Subtidal Fringe Zone
(about 0 to minus 2 feet below seal level)
This zone is only uncovered during the lowest tides. The most densely populated of the tidal zones, it is marked by the brown kelp Laminaria and an increase in the growth of red algae such as Gigartine, Iridea and coralline red algar, Sessile, soft-bodies animals such as sponges, hydroids, bryozoans and tunicates cover the rocks. Sea Stars are abundant as well as Bat Stars, Purple Urchins, Giant Green anemones, Black Chitones and Kelp Crabs. It was once common to find Black Abalone in protected areas.
Conclusion
Threats to the rocky intertidal habitats depend on location and access. Human impact, pollution, storm water runoff, oil spills, agriculture runoff, bacteria in dog poop, and once through cooling from power or desalination plants are all major threats to the survival within the intertidal habitats. Common ways of destruction by human impact include walking on or taking of the live species. National Marine Sanctuary designation would offer signage and education of how to enjoy without destroying the rocky intertidal habitats.
"Think Blue Main"
