Table 6. Factor loadings from principle components analysis (PCA) greater than 0.7 for benthic aquatic insect variables and proportion of variation explained by each principal component
[EPT, Ephemeroptera-Plecoptera-Trichoptera]
Benthic
aquatic insect variable |
First
principal component |
Second
principal component |
Third
principal component |
Fourth
principal component |
| Percent EPT taxa | –0.904 |
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| Percent filterers | .722 |
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| Hilsenhoff’s biotic index | .937 |
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| Number of taxa | 0.874 |
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| Shannon-Weiner diversity index | .968 |
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| Margelef’s richness index | .934 |
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| Simpson’s heterogeneity index | .856 |
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| Percent shredders | 0.858 |
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| Percent Oligochaeta | –0.953 |
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| Proportion of variation explained | .263 |
.293 |
.126 |
.140 |
| Proportion of total variation explained | .822 |
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