| 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). |
