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

5.0 Benthic and Epibenthic Invertebrates
Epibenthic macroinvertebrates were collected at the same 19 stations sampled for fish.
Methods specific to the infaunal and macroinvertebrate surveys are described below.
5.2.1 Infauna
As in previous studies of the harbors, the box
core samples were separated into 0.06 and
0.04 m 2 sections using an acrylic divider
(MEC 1988, 1997, 1999; SAIC 1996). The
larger section was used for the infaunal
sample. The infaunal sample size is similar
to historical studies, which collected benthic
infauna with 0.06 to 0.0625 m 2 coring devices
(e.g., HEP 1976, 1980), although a 0.1 m 2
coring device also has been used (e.g., MBC
1984, City of Los Angeles 1999).
Recovery of at least 10 cm of the upper
sediment layer with a relatively undisturbed
surface layer was considered sufficient for analysis. Rejected cores were discarded and resampled.
Each sample was processed through a 1.0-mm mesh screen and placed in a labeled
sample jar(s); 7% magnesium sulfate (MgSO 4 ) seawater solution was then added to relax the
collected animals. After approximately 30 minutes, the sample was fixed with buffered formalin
to yield a 10% formalin-seawater solution. Samples were uniquely labeled by station.
Some of the stations were also sampled with a Van Veen grab sampler. The Van Veen sampler
is routinely used to monitor the Terminal Island Waster Reclamation Plant in Los Angeles
Harbor and is used in the Southern California Bight Regional Monitoring Program. Because a
box core device has been used for most collections in the harbors, a comparison study was
conducted to determine the comparability of the data obtained with the two sampling
techniques. Van Veen samples were processed in the same way as box core samples.
In the laboratory, infauna samples were transferred from formalin to 70% ethanol within 7 days
of sampling for long-term preservation. Infaunal samples were sorted into major taxonomic
categories (annelids, crustaceans, echinoderms, molluscs, other minor phyla) using a
stereoscopic microscope. Samples with extremely high abundance by a few species were split
to yield smaller samples for analysis; count data were scaled-up to the whole sample depending
on the fraction sorted. Whole samples were analyzed for all but a few of the collected samples.
Sorted organisms were placed into vials containing 70% ethanol for long-term storage.
Qualified taxonomists identified and counted the organisms to the lowest practicable taxon
(usually species). Wet weight biomass (to nearest 0.01gram) was quantified for each taxonomic
group after the species were identified.
5.2.2 Epibenthic Macroinvertebrates
Epibenthic macroinvertebrates were collected during the day and night along with fish during the
three otter trawl surveys (see Section 3.2.2 for a description of methods). Collected
invertebrates were identified to the lowest practicable taxon (usually species) and weighed (wet
weight biomass in grams [g]) in the field. Organisms not identified in the field were preserved in
buffered formalin and returned to the laboratory for identification and weighing.
5–2 2008 Biological Surveys of Los Angeles and Long Beach Harbors
April 2010