** Variables that remained significant after the toxicant-loaded principal components (PC1, PC3 and PC4) were forced into the stepwise regressions prior to the testing of the habitat variables (Model 1 regression confirmation; see text for details). *** Variables that remained significant after the habitat principal components (PC2, PC5, and PC6) were forced into the stepwise regressions prior to the testing of the toxic variables (Model 2 regression confirmation; see text for details). |
|||||||||||||||||||||
| Table 12: Results of stepwise multiple linear regression models for the three year data sets: a.1. benthic metrics versus toxicity units for pyrethroids, habitat metrics, and metals to TEL ratios for Arcade Creek; and a.2. benthic metrics versus principal components of the environmental data for Arcade Creek; b.1. benthic metrics versus toxicity units for pyrethroids, habitat metrics, and metals to TEL ratios for the three Salinas streams; and b.2. benthic metrics versus principal components of the environmental data for the three Salinas streams. Only variables that were significant at α=0.01 were included in the models (NS= not significant; NA=not analyzed because few, if any, of the samples had the benthic metric present). The direction of the relationship for each significant variable is indicated (+ = direct; - = inverse), as is the contributed R2 value. |
