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

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Bolsa Chica Lowlands Restoration Monitoring 2008 Annual Report BOLSA CHICA LOWLANDS RESTORATION PROJECT Monitoring Program Annual Report - 2008 EXECUTIVE SUMMARY The construction phases of the Bolsa Chica Lowlands Restoration Project were principally complete by the end of 2006, including the opening of the Full Tidal Basin (FTB) to the ocean in August 2006. This report presents the biological and physical monitoring program data collected in 2008, documenting the conditions within the restored areas two to three years post-restoration. The biological, physical, and beach monitoring programs reported in this annual report were conducted following the Bolsa Chica Lowland Restoration Project Biological Monitoring and Follow-up Plan and the Bolsa Chica Lowlands Restoration Project Beach Monitoring Plan, both prepared by the U.S. Fish and Wildlife Service in 2001. The monitoring team included Merkel & Associates, Moffat & Nichol Engineers, Coastal Frontiers, and Chambers Group, Inc. The findings are summarized in the following sections. VEGETATION/HABITAT The distribution, composition, and evolution of vegetation communities and unvegetated habitats were monitored through the use of aerial photography and quantitative transect methods. The May 2008 assessment of habitats at Bolsa Chica mapped ten vegetated and seven non-vegetated habitats within the 402-ha (994-acre) study area. Open water and salt panne were the most extensive unvegetated habitats. Southern coastal salt marsh was the most extensive vegetated habitat, occurring primarily as a fringe to salt panne in the Seasonal Ponds and Future Full Tidal Basin, while providing nearly complete cover in the Muted Tidal Basins (MTBs). In 2008, only the west MTB was open to tidal influence and the marsh there had had limited time to respond prior to the monitoring. It is anticipated that this basin and the central and east MTBs will have shifts in marsh distribution in the coming years as all basins are opened to the FTB. The lowest lying areas will be converted to open water and mudflat, while marsh will be able to expand into higher areas previously dominated by non-native weeds, once they are eliminated by the salt water influence. The MTBs were designed to support 51.1 ha (126.3 acres) of salt marsh habitat. In 2008 the three basins had a total of 49.8 ha (122.9 acres) of salt marsh. Salt marsh distribution is also expected to change in the FTB, particularly on Rabbit Island as lowlying marsh continues to convert to mudflat. The FTB was designed to eventually support 7.7 ha (19.1 acres) of pickleweed. In 2008, approximately 4.9 ha (12.4 acres) of coastal salt marsh were present in the basin. Salt marsh will be gained at the higher elevations of Rabbit Island as non-native vegetation continues to convert to mid and high marsh. Additionally, pickleweed on the cordgrass bench in the FTB is expected to expand along the base of the riprap in the coming years. Cordgrass (Spartina foliosa) and eelgrass (Zostera marina) were transplanted throughout the FTB in August 2007. By August 2008, one year post-transplant, the eelgrass had doubled in distribution to cover 0.8 ha (0.9 acre) and is expected to expand substantially in the coming years. Approximately Merkel & Associates, Inc 1
Bolsa Chica Lowlands Restoration Monitoring 2008 Annual Report 196 m 2 of cordgrass had become established in the FTB one year post-transplant. It is expected that the cordgrass will expand to form continuous patches suitable as habitat for light-footed clapper rails (Rallus longirostris levipes) within four to five years of transplant. Investigations of plant species composition along nineteen transects in the restored areas found the Muted Pocket Marsh (MPM) to support the most diverse salt marsh habitat, with minimal non-native species. Rabbit Island in the FTB was the second most diverse, but had a higher component of weedy species, particularly iceplants. A population of the rare plant coast woolly heads (Nemacaulis denudata var. denudata) persists on Rabbit Island and will need immediate protection through removal of the iceplant that is encroaching on its remaining populations. The salt marsh in the MTBs is low in diversity, but forms a dense canopy of pickleweed (Sarcocornia pacifica) that is heavily used by Belding’s Savannah sparrows (Passerculus sandwichensis beldingi) for nesting each year. The next full vegetation monitoring event, including aerial photography, habitat mapping, and transect surveys, will be conducted in summer 2011 (Year 5) as called for in the Monitoring Plan. Additional photography and habitat mapping will be done in 2009 to document interim conditions. FISH COMMUNITY The 2008 fish community sampling was completed in January, April, July, and October. Sampling was performed during daylight hours at two stations in the FTB, one in the MPM, and two in the MTBs. Sampling equipment included an otter trawl, purse seine, large beach seine, and small beach seine as appropriate for the station depth and accessibility. Captured fish were identified, counted, measured, and weighed. Physical water quality parameters were measured coincident with the fish sampling efforts. A total of 42 fish species were captured in 2008 at all stations. Thirty-nine species were captured in the FTB, dominated by topsmelt (Atherinops affinis) (46% of the total catch), California killifish (Fundulus parvipinis) (6% of the total catch), and California grunion (Leuresthes tenuis) (9% of the total catch). Anchovy (Anchoa sp.) comprised only 7% of the total catch and were present primarily in July. The other species captured were increasingly associated with structured habitats due to the spread of eelgrass habitat, particularly in the southern half of the basin. Fish densities were generally low in January and April and much higher in July and October, driven primarily by the number of atherinids captured. Ten fish species were captured in the west and central MTB in 2008. Only the west MTB was directly open to the FTB. Topsmelt and killifish were the most abundant species. Diversity and biomass are anticipated to increase as the MTBs are all opened to the tidal influence of the FTB in the future. The MPM, which is hydrologically separate from the restoration project area, was generally found to be low in diversity but high in abundance of species foraged on by many birds. Nine species were captured, with topsmelt and California killifish the most abundant year round, reaching their peaks in July. Staghorn sculpin (Leptocottus armatus) and longjaw mudsucker (Gillichthys mirabilis) were occasionally abundant. The restoration project and creation of the FTB has increased the availability of important bay habitat, provided nursery functions for many species of marine fish, and thereby improved southern California fisheries resources. Nearly every fish species captured during the 2007 and 2008 monitoring was Merkel & Associates, Inc. 2
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2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

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