3.4 Biological Resources
shallow subtidal to a depth of about -30 feet MLLW, an inner shelf zone from about -30 to -80 feet
MLLW, middle shelf from about -80 to -300 feet MLLW, and outer shelf zone from about -300 to -600
feet MLLW.
Sandy beaches represent unstable habitats with seasonal cycles of sand deposition and erosion. Common
invertebrates observed on San Diego County sandy beaches include beach hoppers (Orchestodea spp.),
sand crabs (Emerita analoga), bean clams (e.g., Donax gouldii), olive snails (Olivella biplicata), and
polychaete worms (e.g., Euzonus spp., Lumbrineris spp., Nephtys californiensis, Scololepis spp.,
Scoloplos spp.).
Bottom-dwelling species in the shallow subtidal zone are well adapted to shifting sediments and turbidity,
with suspension feeders being the dominant group. Species common in sandy-bottom, nearshore areas
off Oceanside include the polychaete (Apoprionospio pygmaea), bean clam (Donax gouldii), amphipod
(Mandibulophoxus uncirostratus), and nemerteans. Similar species would be expected in nearshore
sandy substrates offshore all receiver sites.
The proposed borrow sites fall within the inner shelf zone which is routinely disrupted by wave activity and
oceanic swell. The number of species and abundances of bottom dwelling macroinvertebrates is quite low
in the inner shelf compared to the middle and outer shelf depth zones. Polychaete worms and/or small,
mobile crustaceans dominate the inner to middle shelf infaunal community.
Fish
Speckled sanddabs (Citharichthys stigmaeus) are the most abundant fish species of the inner shelf with
only a few individuals found in the middle shelf zone. Fish commonly found on the bottom in sandy subtidal
habitat (less than 30 feet) off San Diego County beaches include: halibut (Paralichthys californicus),
speckled sanddab, bat ray (Myliobatus californica), and shovelnose guitarfish (Rhinobatos productus).
Northern anchovy (Engraulis mordax ), jack mackerel (Trachurus symmetricus), and Pacific bonito
(Sarda chiliensis) are commonly encountered in the water column just beyond the surfzone.
The California grunion (Leuresthes tenuis) is commonsouthofPoint Conception, California, to Magdalena
Bay, Baja California, in nearshore waters from the surf to a depth of 60 feet. Grunion travel from their
habitat in nearshore waters to specific sandy beaches just after certain full and new moons in conjunction
with their spawning. Grunion on San Diego beaches are typically found on the long, gently sloping beaches
Page 3.4-6
Regional Beach Sand Project EIR/EA
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