Table 1 Comparison of effect sizes in univariate regression models of ACSP in U.S. streams.

Unstandardized regression slopes (b) and standardized slopes (β) are each reported with 95% confidence intervals (shown in parentheses) as well as sample sizes (n) and coefficients of determination (r2). Covariates shown in bold text have slopes (95% confidence intervals) that exclude zero and are therefore considered statistically significant.

Hypothesized effectCovariatenbβr2
TemperatureMean annual air
temperature
1281.32 (−0.11 to 2.75)0.16 (−0.01 to 0.34)0.02
Mean annual water
temperature
1071.32 (0.74 to 1.90)0.39 (0.22 to 0.57)0.15
Canopy shading% Forest cover in
catchment
128−0.56 (−1.06 to −0.06)−0.19 (−0.37 to −0.02)0.03
Stream sizeBasin area1280.10 (0.02 to 0.19)0.21 (0.03 to 0.38)0.03
Mean annual discharge1020.04 (−0.03 to 0.11)0.10 (−0.08 to 0.27)<0.01
HydrologyFlashiness124−0.23 (−0.64 to 0.19)−0.10 (−0.27 to 0.08)<0.01
CV discharge124−0.20 (−0.86 to 0.45)−0.06 (−0.24 to 0.13)0.01
Minimum 30-day
consecutive flow
1241.36 (0.39 to 2.33)0.24 (0.07 to 0.42)0.05
Channel substrateAverage sediment size
(unweighted)
88−0.10 (−0.22 to 0.02)−0.17 (−0.38 to 0.04)0.02
Average sediment size
(weighted)
88−0.12 (−0.24 to 0.00)−0.20 (−0.41 to 0.01)0.03
Land coverImpervious surface in
basin
1243.24 (−0.19 to 6.67)0.16 (−0.01 to 0.34)0.02
% Medium density
urbanization in
catchment
1283.39 (1.11 to 5.68)0.25 (0.08 to 0.42)0.06
% Crop cover in
catchment
1280.86 (−0.46 to 2.18)0.11 (−0.06 to 0.29)0.01