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

Bolsa Chica Lowlands Restoration Monitoring
2008 Annual Report
(Aechmophorus occidentalis). As reported above, in 2008 the basin supported a diverse marine
community, including fish, invertebrates, and eelgrass, which provided important food resources for
migrating, resident, and nesting birds. As eelgrass habitat expands in the basin in the coming years,
more surf scoter, brant, and other diving birds will likely frequent the basin.
The FTB design included low intertidal mudflat suitable for the introduction of cordgrass. The
expansion of the transplanted cordgrass over time should provide habitat attractive to light-footed
clapper rails in the coming years. To facilitate the development of this habitat, it is critical that
appropriate tidal ranges and inundation frequency of the mudflat be maintained through regular
maintenance dredging of the basin inlet.
The Project also created three nest sites that have substantially increased the available habitat for
nesting terns and plovers. The usage of these site and resulting reproductive success will be discussed
further in the next section.
The third most abundant guild was dabbling ducks/geese, which had high counts in February (2,354
individuals), April (982 individuals), and June (322 individuals) and in smaller numbers during the
August survey (31 individuals). The most abundant of the dabbling ducks were northern shoveler,
gadwall, American wigeon followed closely by green-winged teal, northern pintail, and mallard. Most
of the dabbling ducks/geese were observed during February and April with species and numbers
dropping in June and absent in August. Several brant were recorded foraging in eelgrass in the FTB
and mallard were the only species still present during the August survey.
Another element of the Project involved the introduction of muted tidal influence to the Muted Pocket
Marsh. Although avian data from this previously freshwater site have not been located, the usage of
the basin following the conversion to a saltwater system has been notable. This site had consistently
high densities of birds, provided an easily accessible viewing area for the public, and supported several
Belding’s Savannah sparrow breeding territories.
Prior to the restoration, the expanses of pickleweed in the Muted Tidal Basins were non-tidal and
experienced hypersaline sediment conditions and the environmental extremes of wet and dry seasons.
The Project design included restoration of a muted tidal influence to these three basins in order to
provide greater environmental stability to the salt marsh, improve its quality for Belding’s Savannah
sparrow, and to create a more functional salt marsh with open water and intertidal mudflats, as well as
low and mid marsh. Only the west MTB was open to tidal influence in 2008. This basin maintained a
high level of Belding’s Savannah sparrow nesting while also providing open water for large numbers
of wintering ducks and foraging terns, and some mudflat for foraging sandpipers. The regulation of
water levels in this basin was hampered by the accumulation of sand in the FTB inlet, preventing tides
from falling as low as desired in the FTB and west MTB. It is anticipated that after the 2008/2009
maintenance dredging cycle, and the opening of the other two MTBs to tidal influence, the entire MTB
system will be able to move toward an equilibrium of habitat availability for multiple avian guilds.
Diversity within the entire study area (135 species in 2008) is comparable to diversity observed at
other coastal salt marshes in southern California. The bird usage of Batiquitos Lagoon in San Diego
County was monitored, using similar methods to those of the present study, for 10 years following the
restoration of tidal influence to the system. Two years post-restoration, 133 species were documented
at Batiquitos Lagoon (M&A 1999). Batiquitos Lagoon is a smaller site (approximately 2/3 the size),
Merkel & Associates, Inc. 86