1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 2:PROBLEM FORMULATION
The following measures, which are listed in greater detail in Table 2-21, were identified for
the Bolsa Chica Lowland project site:
• Measures of Exposure—Concentrations of COPECs in sediment/soil, surface water, and
field-collected biota.
• Measures of Effects—Responses of terrestrial or aquatic plants and wildlife (actual or
potential toxic effects) to COPECs in sediment/soil, surface water, and biota; responses
of bioassay organisms to COPECs in exposure media (e.g., sediment, pore water, and
surface water); potential or actual bioaccumulation of COPECs in terrestrial or aquatic
plants and wildlife.
• Measures of Ecosystem and Receptor Characteristics—Habitat quality and home range of
representative species in comparison with the size of the contaminated area at each site.
The linkages between assessment endpoints and measures are developed in the Analysis
phase of the ERA. The Analysis includes the Exposure Characterization, which results in an
exposure profile, and the Ecological Effects Characterization, which results in the stressorresponse
profile. The assessment endpoints and measures will be evaluated in more detail
during the Risk Characterization phase of the ERA.
2.5 Ecological Conceptual Site Model
The ecological conceptual site model combines information on COPECs, potential ecological
receptors, potential exposure pathways, assessment endpoints, and measures presented in
Sections 2.2, 2.3, and 2.4, providing an overall picture of site-related exposures that can
focus the remaining evaluation of COPECs in the ERA. A preliminary ecological conceptual
site model is presented in this section (Figure 2-5). The model accommodates the various
sources of chemicals, migration pathways for chemicals, potential routes of exposure, and
potential receptors at the site.
2.5.1 Identification of Representative Species
This section describes criteria used to select representative species for the Bolsa Chica
Lowlands. Representative ecological receptors were identified as the aquatic, semi-aquatic,
and terrestrial plants and wildlife most likely affected by COPECs. Representative receptors
include primary and secondary consumers that are aquatic (e.g., microinvertebrates,
macroinvertebrates, and fish), semi-aquatic (e.g., shorebirds and other birds that feed on
aquatic biota), and terrestrial (e.g., plants, soil invertebrates, upland birds, and mammals).
The potential plant and wildlife species that could represent ecological receptors were
determined through meetings with the Bolsa Chica Technical Committee, through direct
observations of plants and wildlife in the Bolsa Chica Lowlands, as well as listings of species
that are expected to occur and special-status species that may be found (as described in
Section 2.2.2). Representative species selected are from communities that are commonly
found in the different habitat types at the site. Representative species could also be specialstatus
species for which suitable habitat has been identified. The communities potentially
exposed directly or indirectly (i.e., through the food chain) to COPECs in the Bolsa Chica
Lowlands are composed of estuarine/marine plants, free-swimming and benthic
invertebrates, and fish; semi-aquatic and upland birds; and terrestrial mammals.
ERA REPORT 2-14 SAC/143368(002.DOC)
7/31/02