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. 2012 Jun 28;8:14. doi: 10.1186/2046-9063-8-14

Table 1.

PCA and subsequent correlation analysis between stream variables and derived principal components (PCs)

Stream variables
 Principal components 2
  Min. Max. Mean ( ± SE) PC1 PC2 PC3
Spring
  
  
  
  
  
  
Temperature (°C)
 7.0
 16.0
 11.1 ± 0.30
 -0.505 **
 -0.363 *
 -0.118
pH
 5.6
 7.5
 6.5 ± 0.05
 0.554 **
 -0.383 *
 0.325
% Dissolved Oxygen
 93.2
 115.4
 102 ± 0.66
 -0.131
 -0.710 **
 0.130
Conductivity (°S cm-1, 25°C)
 16
 152
 40 ± 3.2
 0.483 **
 -0.073
 0.377 **
Depth (m)
 0.08
 1.88
 0.40 ± 0.047
 0.783 **
 0.258
 -0.250
Velocity (m/s)
 0.09
 0.87
 0.40 ± 0.024
 -0.020
 -0.816 **
 -0.139
Width (m)
 0.5
 20.0
 6.6 ± 0.67
 0.807 **
 -0.005
 -0.272
Discharge (m3/s)
 0.01
 17.9
 1.5 ± 0.40
 0.861 **
 -0.089
 -0.280
Seston (mg/L)
 2.0
 74.0
 14.0 ± 0.30
 0.144
 -0.623 **
 0.151
Streambed-particle size 1
 1.0
 6.0
 2.0 ± 0.26
 -0.308
 -0.788 **
 -0.123
Riparian vegetation 1
 1.0
 3.0
 2.1 ± 0.14
 -0.347 *
 -0.087
 -0.736 **
Canopy cover 1
 1.0
 3.0
 1.6 ± 0.09
 -0.418 *
 0.151
 -0.655 **
% variance explained in PCA
  
  
  
  
  
  
Proportion
  
  
  
 24.9
 21.8
 15.0
Cumulative
  
  
  
 24.9
 46.8
 61.7
Summer
  
  
  
  
  
  
Temperature (° C)
 13.0
 29.0
 20.0 ± 0.49
 0.514 **
 -0.560 **
 0.054
pH
 5.80
 7.9
 7.1 ± 0.06
 0.085
 0.239
 0.782 **
% Dissolved Oxygen
 78.8
 106.7
 93.25 ± 0.93
 -0.021
 0.650 **
 -0.433 *
Conductivity (°S cm-1, 25°C)
 10
 235
 73 ± 7.46
 0.303
 -0.137
 0.897 **
Depth (m)
 0.03
 0.73
 0.18 ± 0.029
 0.873 **
 0.003
 -0.124
Velocity (m/s)
 0.02
 0.67
 0.31 ± 0.018
 0.424 *
 0.616 **
 -0.296
Width (m)
 0.30
 36.00
 7.5  ± 1.20
 0.871**
 0.162
 0.219
Discharge (m3/s)
 0.01
 9.38
 0.73 ± 0.209
 0.889 **
 0.236
 0.019
Seston (mg/L)
 2.8
 50.0
 14.6 ± 0.49
 0.237
 -0.079
 0.091
Streambed-particle size 1
 1.0
 6
 2.0 ± 0.24
 -0.124
 0.892 **
 -0.098
Riparian vegetation 1
 1.0
 3
 2.3 ± 0.13
 -0.121
 0.386 *
 0.076
Canopy cover 1
 1.0
 3.
 2.0 ± 0.15
 -0.473 **
 0.220
 0.056
% variance explained in PCA
  
  
  
  
  
  
Proportion
  
  
  
 26.4
 20.3
 15.8
Cumulative       26.4 46.8 62.6

1 Dominant streambed-particle size (mud = 1, sand = 2, small stones = 3, rubble = 4, boulders = 5, bedrock = 6), riparian vegetation (open = 1, brush = 2, forest = 3) and canopy cover (none = 1, partial = 2, complete = 3) are ranked variables, with medians presented.

2 Significant correlation at * P < 0.01, ** P < 0.001.