appendix b final 2008 biological surveys of los angeles and long ...

Executive Summary
Van Veen) and analysis of samples that differ between 0.06 m 2 and 0.1 m 2 in surface area.
Results of this comparison found no statistical differences in abundance or number of species
between gear types.
For macroinvertebrates collected during trawl surveys, invertebrate catch varied among
stations, and no distinct spatial patterns in species distribution or abundance was observed.
Substantially more macroinvertebrates were collected at night than during the day and in winter
and spring surveys compared to the summer survey. The most common species included
black-spotted shrimp (Crangon nigromaculata), ridgeback prawn (Sicyonia ingentis), black-tailed
bay shrimp (Crangon nigricauda), Xantus’ swimming crab (Portunus xantusii), and Heptacarpus
shrimps.
RIPRAP ASSOCIATED ORGANISMS
A total of 334 species of invertebrates were identified from three tidal zones within the riprap
community. Distinct tidal zonation was observed with increasing numbers of species with
increasing depth. Mean total abundance was highest in the lower intertidal, lowest in the upper
intertidal, and intermediate in the subtidal zone. Across all tidal zones, crustaceans were
numerically dominant, followed by polychaetes, echinoderms, molluscs, and other phyla.
Historical studies have noted relatively greater community development in outer harbor
compared to inner harbor areas (MEC 1988, MEC 2002). However, the present study noted
general similarities in these communities throughout the harbors. Exceptions were for diversity,
which was somewhat greater at outer harbor breakwater stations compared to inner harbor
locations, but these differences were mainly associated with the upper intertidal zone.
Community summary measures did not show distinct trends among inner and outer harbor
stations for the lower intertidal and subtidal zones, suggesting some improvement in
environmental quality at inner harbor stations since the 2000 study.
KELP AND MACROALGAE
Within the Ports, the majority of kelp and macroalgae surface canopy is closely associated with
the outer breakwaters and with riprap structures in the outer harbor and in locations facing the
harbor entrances. While algal diversity in the Ports is considered relatively low, there is a
general pattern of decreasing algal diversity from outer to inner harbor locations. In addition,
seasonal patterns in the surface kelp canopy were evident during the present study, similar to
those noted during the 2000 baseline study.
The previous baseline study in 2000 was the first systematic effort to quantify kelp surface
canopy coverage throughout the Ports. Total mapped canopy cover of Macrocystis in the spring
was 24.8 acres, decreasing to 14.2 acres in fall (43% decrease). During the present baseline
study, Macrocystis canopy totaled 77.8 acres in spring and decreased to 50.4 acres in the fall
(35% decrease). Seasonal declines in kelp canopy cover for both studies are likely due to
natural die-offs between winter and fall. Overall, the Macrocystis canopy extended greater
distances along outer breakwaters and the kelp beds appeared broader and more contiguous
during the present study compared to the 2000 survey.
Dominant macroalgal communities in the present study were similar to those described in MEC
(2002) and included Sargassum, Ulva, Colpomenia, Chondracnathus, and Halymenia. Outer
harbor stations had from 4 to 11 dominant groups during the present study compared to 2 to 11
groups during the 2000 survey. The present study reported substantially more species per
station than the 2000 surveys (5 to 11 species in 2008, one to six species in 2000). The
reasons for these inner harbor differences between surveys are unknown, but could be related
to improved habitat conditions in the Ports.
ES–4
2008 Biological Surveys of Los Angeles and Long Beach Harbors
April 2010