2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

Bolsa Chica Lowlands Restoration Monitoring
2008 Annual Report
Epifauna
The epifauna documented in the 1-m quadrat assessment in January 2008
are presented in Table 1-17 (all replicates combined) and included only a
few bivalves and tunicates at Station 1 and no animals at Stations 2 or 3,
although several Navanax inermis were observed outside of the quadrat at
the –2-foot elevation at Station 2.
In the July 2008 quadrat sampling, considerably more epifaunal
invertebrates were observed, with Station 2 at the –2-foot elevation having
the most animals (Table 1-17). At Stations 1 and 3 there were large groups
of Bulla gouldiana and egg masses present just outside of the quadrats.
Also noted in July were large numbers of Hemigrapsus oregonensis and
Pachygrapsus crassipes throughout the riprap surrounding the FTB.
Bulla gouldiana and egg masses.
The epifaunal invertebrates captured in the fishing nets in 2008
are presented in Table 1-18 by station and sampling quarter (all
replicates combined). Considerably more diversity was recorded
than was seen in the quadrat assessment due the greater area and
depth range sampled. Species occasionally seen in high numbers
were the pink shrimp Pandalus sp., the small kelp humpback
shrimp (Hippolyte clarki) commonly associated with eelgrass,
A. ventricosus size classes in the FTB.
various tunicates, B. gouldiana, and Argopecten ventricosus. The
scallop A. ventricosus was captured during every quarter in the FTB and in the full range of sizes from
newly settled to fully-grown. Six non-native species were identified (as indicated in the table by an
asterisk), including the Japanese mussel (Musculista senhousia), a highly invasive non-native mussel
present in many California bays and estuaries and detected during the first benthic monitoring in
October 2007 (Merkel & Associates 2008).
Though not measured by the benthic monitoring program, the
development of the invertebrate community on the shoreline was
dramatic during 2008, with the loose rocks that are scattered over the
mud shoreline of the FTB becoming heavily encrusted by the nonnative
Mediterranean mussel (Mytilus galloprovincialis), the limpet
Crepidula fornicata, native oysters (Ostreola conchaphila), and
barnacles (Balanus sp.). These rocks were left behind following the
completion of the FTB construction and have added complexity to
the large mudflats of the basin. Octopus (Octopus bimaculoides), navanax, and nudibranchs were
often observed in the pooled water at the base of the FTB riprap and in the shoreline eelgrass beds.
Encrusting molluscs on the FTB mudflats.
Merkel & Associates, Inc. 62