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

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Bolsa Chica Lowlands Restoration Monitoring 2008 Annual Report July 2008, roughly two years after the basin was opened to the ocean, and occurred in the FTB, west MTB, and MPM. Other non-native invertebrates documented included the invasive oriental shrimp (Palaemon macrodactylus). This species is considered established in California, and Ricketts et al. (1968) proposed that this species was responsible for the disappearance of native species of shrimp Crangon spp. in some cases. It is generally thought to be introduced by ballast water releases, from which it spreads to surrounding estuaries planktonically. The Mediterranean mussel (Mytilus galloprovincialis) was first observed in the FTB during the first survey in October 2007, and was also found during every quarter in 2008. This non-native species is well established throughout California. The Japanese mussel (M. senhousia) is another non-native presumed to eventually arrive at Bolsa Chica. This species settles from the plankton onto soft substrate and can form dense mats of entangled fibrous threads. This mat and the thousands of mussels that can colonize per square meter can inhibit the feeding of native filter feeders and the spread of eelgrass. Although there is no evidence of dense mats having formed at this time at Bolsa Chica, their capture in the fishing nets in October 2007 and April and July 2008 indicates their presence in the FTB and Muted Pocket Marsh. Cordgrass and eelgrass transplanted from Upper Newport Bay and the Port of Los Angeles in August 2007 was observed to have M. senhousia in its roots prior to planting in Bolsa Chica. This species may have already arrived in the FTB through the settlement of planktonic larvae prior to the transplant of the cordgrass and eelgrass. There is no effective means to control this species, however it has been documented that dense, healthy eelgrass beds can inhibit the growth of M. senhousia (Allen and Williams, 2003). The non-native bryozoan Zoobotryon verticillatum was observed in July and October 2008 in the Muted Pocket Marsh and at Station 2, respectively. This species is also well established in southern California bays and estuaries. It can seasonally grow to great expanses that can reduce the density and vigor of eelgrass beds, and smother native flora and fauna. Japanese wireweed (Sargassum muticum) is a seaweed native to Japan that is widespread in Southern California bays, commonly found on rock, riprap, or other hard substrate. This brown alga has been documented to compete with and displace native species of seaweed and eelgrass by reducing light through shading. At Bolsa Chica in 2008, the seaweed has not yet colonized the riprap, rather was observed loose in the FTB. The holdfasts of the seaweed were secured to highly motile scallops (A. ventricosus), which were serving as minireefs for the S. muticum to settle onto and be transported by. It is likely that hard substrate within the basin will become Sargassum muticum attached to a scallop. colonized with S. muticum following future reproductive events by the population on the scallops. There are no feasible means to control or prevent colonization by S. muticum, nor is its potential biological impact clearly understood in southern California. Future field work will also look for Sargassum filicinum, a related species recently discovered in some southern California bays and estuaries, and at Catalina Island. Merkel & Associates, Inc. 97
Bolsa Chica Lowlands Restoration Monitoring 2008 Annual Report Non-native vertebrates observed in 2008 at Bolsa Chica included the yellow-fin goby (the only nonnative fish documented) and several birds, including rock pigeon and great-tailed grackle (Quiscalus mexicanus). The grackle is an invading species from Sonora or southern Arizona and is breeding at Bolsa Chica. There are numerous non-native plant species in the wetlands of southern California, however the Bolsa Chica Lowlands are fortunate to be devoid of two of the most invasive and difficult species. There is little to no occurrence of the giant reed (Arundo donax) or pampas grass (Cortaderia selloana) within the study area. Any observations of these species will be immediately reported to CDFG for removal. Hottentot fig (C. edulis) is widespread in the system and is being removed by CDFG and volunteer hand labor as resources permit. Black mustard (Brassica nigra) is widespread on the road margins and along the northeast corner of the site. Seasonally timed herbicide application would benefit the control efforts for these species. In some areas, particularly along the northern and eastern boundary of the side, a few highly invasive terrestrial weeds were observed in the early stages of establishment. These include artichoke thistle (Cynara cardunculus) and castorbean (Ricinus communis). The size and distribution of these specific plants is quite limited, unlike the ice plant and mustard discussed above. Early removal or herbicide treatment of these individuals in spring, prior to release of seeds into the system, would be tremendously helpful in restricting their spread and may result in financial and labor saving by avoiding their widespread establishment, such as currently seen with the mustard and others. The California Invasive Plant Council recommends prompt removal or treatment of these species upon their discovery if possible. Also to note, Spanish false fleabane (Pulicaria paludosa) was Species to be targeted for removal during early stages of invasion. identified in Zone 38. Recommendations • Employ seasonally timed herbicide application to benefit the control efforts of non-native plant species. • Conduct early spring removal or herbicide treatment of invasive terrestrial weeds, prior to release of seeds into the system. • Continue assault on Hottentot fig with more strategic seasonal timing of herbicide application. Merkel & Associates, Inc. 98
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Santa Barbara Los Angeles Outer Bol
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BS PM Rep3 Muted Pocket Marsh BS PM
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Total Future Full Tidal Basin FFTB
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Western Snowy Plover Nesting at Bol
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2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

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