3.4 Biological Resources
As one moves further offshore to depths where seasonal sand movement is less, hard substrates do not
need to have as high a relief to support perennial species. Kelp beds are an important habitat associated
with offshore reefs. The kelp community, dominated by giant kelp (Macrocystis pyrifera), ranges from
water depths of about -20 feet to -120 feet MLLW. It is a unique habitat that provides food, shelter,
substrate, and nursery areas for many species of fish and invertebrates. Invertebrates found in kelp beds
include lobster, sea stars, sea urchins, and mollusks. Brown, green, and red (fleshy and coralline) algae
occur in kelp beds. Surfperch, rockfish (Sebastes spp.), and wrasses (senorita, rock wrasse and
sheephead) are usually the dominate fish type.
Kelp beds also provide a large food supply for marine birds and mammals. Cormorants are the birds most
closely associated with California kelp beds; however, gulls commonly scavenge on the surface canopy,
and pelicans and terns exploit schooling fish along the canopy's edge. Mammals such as sea lions, seals,
and whales use kelp beds as transitory foraging areas. The giant kelp is commercially harvested for use
ina variety of food products, pharmaceuticals, adhesives, paper products, paints and finishes, rubbers, and
textiles.
Giant kelp is adversely affected by sedimentation and turbidity. Large amounts of shifting sediment can
scour the bottom, bury small plants, and prevent settling of microscopic spores, all of which can reduce the
cover in the number of adult plants. Giant kelp is one of the first species to be eliminated in physically
stressed habitats (wave or sand scour). The density and abundance of kelp canopy varies by location,
season, and year. Kelp beds in southern California commonly deteriorate to some degree during summer
and fall when temperatures are higher and nutrient concentrations are lower. El Nio conditions, which
result in higher than average temperatures and low nutrients have been linked to periodic and widespread
reductions in kelp canopy. Kelp beds in northern San Diego County are in the process of recovering from
the recent 1997/1998 El Nio.
Mammals
Both marine and terrestrial mammals occur in the project area.
Marine
Several species of mammals occur in nearshore waters adjacent to the receiver sites and in offshore waters
near the borrow sites. California sea lions (Zalophus californicanus) and harbor seals (Phoca vitulina)
Regional Beach Sand Project EIR/EA
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