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

6.0 Riprap Biota
diver collection methods used during this survey differed from the previous (2000) baseline
study (MEC 2002), particularly relative to samples collected in the subtidal zone. For example,
the previous study sampled in the upper intertidal (barnacle zone), middle intertidal (mussel
zone), and a “shallow subtidal” zone (a few feet below Mean Lower Low Water). Samples for
the current survey were collected based on a combination of tidal zones and biological zones,
collecting samples from the upper intertidal (equivalent to the barnacle zone), middle to lower
intertidal (equivalent to the mussel zone), and subtidal (near the deepest extent of the riprap,
but about 3 to 5 feet shallower than the soft substrate bottom to avoid the ecotone/highest
sedimentation zone). Actual differences in collection depths between the current and previous
surveys cannot be determined more precisely due to the lack of more detailed sampling depth
descriptions.
Los Angeles Harbor Station LARR1 was
located on the Middle Breakwater and had
riprap boulders 5 to 6 feet in diameter.
Station LARR2, in the East Basin, was
comprised mostly of cement slabs, with few
rocks in the lower zone. The subtidal area at
this site had little to no hard bottom substrate
to sample and was covered with thick silt.
Winter samples were taken only from the
upper tidal zone and this station was
relocated for the summer sampling a
distance of approximately 800 m (0.5 mile)
into the next cove in front of Banning's
Landing Community Center. This location
was chosen for its relatively close proximity
to the previously sampled location during the winter survey, similar inner harbor habitat location,
and riprap rock throughout all sampling depths. Station LARR3 was in the Los Angeles West
Basin near the TraPac pier and had no existing riprap, so an outer pier piling was sampled.
Station LARR4 was situated at the end of the G.A.T.X. Terminal in outer Los Angeles Harbor.
Similar to Station LARR2, not all tidal zones could be sampled in winter (lower tidal zone
excluded) even though this site was comprised of large concrete blocks in the upper and middle
tidal zones. For the summer survey, this station was moved approximately 100 m west to a
location where riprap rock occurred throughout all tide zone depths. All samples were collected
in each tide zone at all stations during the summer survey.
Long Beach Harbor Station LBRR1 was located at the Pier J breakwater. Riprap boulders were
4 to 5 feet in diameter. Station LBRR2 was near the Turning Basin of Cerritos Channel near
some gas lines that extend into the water. The upper and lower tidal zones consisted of small
boulders, 1 to 2 feet in diameter. The subtidal zone was characterized by silt with shell hash
and a few rocks. Station LBRR3 was in the Long Beach West Basin. Large cement slabs were
found in the upper and lower tidal zone, and cement slabs and rocks made up the substrate in
the subtidal zone. For the summer survey, LBRR3 was moved a short distance west (~150 m)
so that the samples were taken on rock riprap similar to most stations. Station LBRR4 was in
the Southeast Basin. The upper and lower tidal zones consisted of boulders ranging from 1 to 3
feet in diameter, whereas boulders in the subtidal zone were 3 feet in diameter.
Similar to previous baseline surveys, riprap sampling for understory organisms in the present
study utilized two quadrats (7.5 by 15 cm), established at three tidal levels (upper intertidal,
lower intertidal or “middle tidal zone”, and lower subtidal). For each tidal level, all of the
organisms in a randomly sited 7.5 by 15 cm quadrat were removed by scraping with a
6–2 2008 Biological Surveys of Los Angeles and Long Beach Harbors
April 2010