3.4 Biological Resources
many do not persist. Opportunistic species such as the feather boa kelp (Egregia menziesii), which more
commonly occurs as a subtidal canopy, actively recruits to intertidal habitats on exposed rock, but rarely
lives more than a year due to sand scouring, sun burn, density-dependent self-thinning, and competitive
exclusion.
Persistent substrates in the low tidal zone and minus tide zone are characterized by a greater diversity of
plants and animals including coralline algae, other red algae, brown algae, surfgrass (Phyllospadix), green
sea anemones (Anthopleura xanthogrammica), purple sea urchins (Strongylocentrotus purpuratus),
California sea hares (Aplysia californica), snails, sponges, and starfish (Asterina miniata, Pisaster spp.).
Wooly sculpin (Clinocottus analis) is one of the more commonly encountered fish in tidepools.
Subtidal reefs in the shallow nearshore also exhibit considerable variation in resource development
associated withthe seasonalonshore and offshore migration of sand, and similar to intertidalreefs, substrate
factors such as relief height, texture, composition, and size largely determine resource development on
nearshore reefs. Higher relief reefs typically support more diverse communities that include perennial
species such as sea fans (Muricea), sea palms (Eisenia arborea), sponges, nudibranchs, and sea stars,
and harbor and attract a variety of fish such as garibaldi (Hypsypops rubicunda), blacksmith (Chromis
punctipinnis), and black perch (Embiotoca jacksoni). In striking contrast, very low relief areas exhibit
reduced species diversity consisting mainly of opportunistic and annual turf vegetation.
Surfgrass is a key species of an important vegetated community that ranges from intertidal to -20 feet
MLLW. In southern California, surfgrass serves as a nursery for the California spiny lobster. Surfgrass,
whichis a long-lived perennial species, persists in rocky areas with shifting sand by having an extensive root
system that binds with sand and having leaves that are tolerant of sand abrasion. However, while surfgrass
may tolerate wet sand cover for many months, the duration and depth of burial that would result in
morbidity has not been studied. Incremental sand burial has been reported to affect blade growth.
Surfgrass recovery rates are slow (three to five years) when recovering from removal of the root mat, but
may be quicker when the rhizomes remain intact. Surveys undertaken in January and February 2000
identified and mapped approximately 42 acres of surfgrass in the intertidal from Oceanside to Torrey Pines
(Appendix D). While the acreage in the nearshore was not surveyed by this method and is not field
verified, hard substrate patterns suggest at least that same amount, and probably more, are present in the
nearshore. This total surfgrass acreage off the North County San Diego shoreline is estimated at 80 to 100
acres.
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