Benthic Metrics b.1 Significant Variables (R2) b.2 Principal Components
Taxonomic Richness -Bifenthrin (0.15), +% Canopy cover (0.11) -PC6 (0.19)
% Dominant Taxon NS NS
Ephemeroptera Taxa NA NA
EPT Taxa NA NA
EPT Index (%) NA NA
Shannon Diversity -Esfenvalerate  (0.14) -PC5 (0.16)
Tolerance Value -Canopy (0.11) NS
% Tolerant Taxa (8-10) +Esfenvalerate  (0.12) NS
% Collectors/Filterers +Esfenvalerate  (0.22) +PC5 (0.22)
% Collectors/Gatherers -Sediment deposition** (0.15) NS
% Grazers +Sediment deposition** (0.27), -Zinc  (0.21), +Lead  (0.15) NS
% Predators +Velocity depth regimes (0.14), +Cypemethrin (0.12), -Arsenic  (0.13) NS
% Shredders NA NA
Abundance (#/sample) NS NS
* The environmental variables with the largest loadings for the environmental principal components (proportion of variance explained by PCs are in parentheses) are: PCI (0.41) = +All of the metals to TELs, and to a lesser extent, +Channel flow, -Channel alteration, and -% Canopy cover; PC2(0.13) = -%Fines, +Embeddedness, +Sediment deposition, +Cobble, +Total Score, +Epifaunal substrate, +Boulder, and +Frequency of riffles/bends; PC3(0.08) = +Cypermethrin TU; PC4(0.06) = +Lambda-cyhal. TU and +Permethrin TU; PC5 (0.05) = +Esfenvalerate TU; PC6 (0.04) = +Deltamethrin TU and +Bifenthrin TU.
** Variables that remained significant after the toxicant-loaded principal components (PC1, PC3, PC4, PC5, and PC6) were forced into the stepwise regressions prior to the testing of the habitat variables (see text for details).
***Variables that remained significant after the habitat principal component (PC2) was forced into the stepwise regressions prior to the testing of the toxic variables (see text for details).
Table 12b: Regression models for Salinas streams