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

5.0 Benthic and Epibenthic Invertebrates
present study (14%) is similar to the 15% reported for the 2000 study (MEC 2002); however, the
proportion of introduced species was substantially less in the present study compared to the 25
reported in 2000. This was due in part to more species being collected in 2000 (409).
However, there also has been further distinction of introduced versus cryptogenic species since
the 2000 study (e.g., Ranasinghe et al. 2005, Foss 2008).
Approximately 12% of the infaunal abundance was comprised of non-indigenous taxa, including
relatively dominant taxa such as Theora lubrica (10%) and Eochelidium sp. A (1.8). The nonindigenous
New Zealand bubble snail, Philine auriformis, accounted for less than 1% of the
macroinvertebrate abundance (Appendix E), which is less than noted during the 2000 study
(MEC 2002).
The relative abundance of Theora lubrica has increased in the harbors since the 1970s as well
as since 2000 (refer to Tables 5.3-6 and 5.4-5). For example, T. lubrica had higher abundance
in areas with finer sediments and at adjacent stations during the 2000 study (MEC 2002). In
contrast, this species occurred at 25 of the 29 stations surveyed during the present study,
although abundance was highest in Los Angeles Harbor.
Other non-native species collected in relatively low abundance included amphipods (Caprella
simia, Corophium heteroceratum, Grandidierella japonica, Monocorophium insidiosum), clam
(Venerupis phillipinarium), mussels (Mytilus galloprovincialis), and polychaete worms (Nicolea
sp. A).
One cryptogenic species dramatically decreased in relative abundance since the 2000 study.
The polychaete Pseudopolydora paucibranchiata represented approximately 22% of the total
infaunal abundance in 2000, but accounted for less than 3% of the abundance in 2008. In
contrast, Nebalia pugettensis-complex accounted for a relatively higher percentage of
abundance in 2008 (6%) compared to 2000 (