Air Quality Criteria for Lead Volume II of II - (NEPIS)(EPA) - US ...

species was observed. Similar, significant negative correlations were found between sediment
Pb levels (132 to 6252 µg/g) and the same macroinvertebrate community metrics and caddisfly
tissue levels. Negative correlations were also found between Cd and Zn in the water and
sediment and the macroinvertebrate community metrics. In an analysis of cumulative toxicity,
Pb was judged to be the most significant metal in sediment related to the cumulative toxicity
measured. This study provided multiple lines of evidence (i.e., mine density, metal
concentrations, bioaccumulation in caddisfly tissue and benthic invertebrate assemblage
structure) of the negative impacts of mining in the Coeur d’Alene River, suggesting that Pb (and
other metals) were primary contributors to the effects observed in the Coeur d’Alene River
watershed (Maret et al., 2003).
AX7.2.5.2 Biotic Condition
In an evaluation of the biotic condition, the SAB framework described by Young and
Sanzone (2002) identifies community extent, community composition, trophic structure,
community dynamics, and physical structure as essential ecological attributes for assessing
ecosystem health. The following two sections describe the effects of Pb on community
composition, community dynamics, and trophic structure. To date, no available studies were
located on the effects of Pb on physical structure (e.g., change in riparian tree canopy height,
ecosystem succession).
Ecosystems and Communities, Community Composition
To measure community composition, an inventory of the species/taxa found in the
ecological system must be conducted. According the SAB framework, useful measures of
composition include the total number of species or taxonomic units, their relative abundance,
presence and abundance of native and non-native species, and information on the presence and
abundance of focal or special interest species (Young and Sanzone, 2002). Focal or special
species of interest can be those that play a critical role in ecosystem processes such as flows of
materials or energy within complex food-webs (Young and Sanzone, 2002). Community
composition as assessed in Pb studies has included the following measures.
AX7-198