Table : Multiple regression models obtained for each of the ten selected metrics. Model types: Lin = multiple linear model, Log = multiple logistic model. Variables as follow: FISH = sampling area; TECH = sampling technique (B: by boat, W: by wading); METH = sampling method (P: partial sampling, W: whole sampling); CAT = catchment class area (1: < 10 km2, 2: 10-99 km2, 3: 100-999, 4: 1000-9999 km2, 5: >10000 km2); LAK = presence of a natural lake upstream (No or Yes); GEO = geology (C: calcareous, S: siliceous); FLOW: flow regime (P: permanent, T: temporary); ELE = elevation; DIST = distance from source; WID = river width; TEMP = mean air temperature; SLOP = river slope; RIVG = river groups (D: Danube, E: Ebro River, MC: Mediterranean rivers from Catalunya, MF: Mediterranean rivers from France; MN: Meuse-group rivers, NP: North Portugal rivers, NE: Northern European plain rivers, R: Rhône river, SE: South West Sweden rivers, UK: United Kingdom rivers, WF: West-France rivers). Mean and s.d.: mean and standard deviation of the residuals of the reference calibration data set (REF-CAL). Hyphen are noted when the variable is not considered in the model.

Ni-INSE / Ni-OMNI / NI-PHYT / Ns-BENT / Ns-RHEO / Ns-LONG / Ns-POTA / %Ni-LITH / %Ns-INTO / %Ns-TOLE
Model / Lin / Lin / Lin / Lin / Lin / Lin / Lin / Log / Log / Log
Intercept / 4.242 / 1.399 / 1.950 / -0.200 / -0.491 / 0.841 / -0.656 / 0.373 / 0.751 / -1.875
FISH / - / - / - / 0.061 / 0.080 / -0.038 / 0.086 / - / -0.122 / -
TECH-B / 0 / - / - / - / - / - / - / 0 / 0 / 0
TECH-W / 1.038 / - / - / - / - / - / - / 0.816 / 0.250 / -0.297
METH-P / 0 / 0 / 0 / 0 / 0 / - / - / 0 / - / -
METH-W / -0.550 / -0.766 / -0.533 / -0.135 / -0.064 / - / - / 0.433 / - / -
CAT-1 / - / - / - / - / - / - / 0 / 0 / - / -
CAT-2 / - / - / - / - / - / - / 0.035 / -0.002 / - / -
CAT-3 / - / - / - / - / - / - / 0.228 / 0.398 / - / -
CAT-4 / - / - / - / - / - / - / 0.574 / 0.431 / - / -
CAT-5 / - / - / - / - / - / - / 0.473 / 0.148 / - / -
LAK-N / - / 0 / 0 / - / - / - / - / 0 / 0 / 0
LAK-Y / - / 0.500 / 0.450 / - / - / - / - / -0.835 / -0.322 / 0.316
GEO-C / - / - / - / - / - / 0 / - / 0 / - / 0
GEO-S / - / - / - / - / - / 0.083 / - / 0.025 / - / 0.181
FLOW-P / - / - / - / - / - / 0 / 0 / 0 / 0 / -
FLOW-T / - / - / - / - / - / -0.178 / 0.179 / 0.297 / -0.710 / -
ELE / 0.674 / 1.356 / 0.702 / 0.427 / 0.472 / -0.063 / 0.326 / 1.566 / - / 0.627
ELE2 / -0.098 / -0.137 / -0.077 / -0.055 / -0.051 / -0.012 / -0.034 / -0.161 / - / -0.087
DIS / - / 0.276 / - / 0.069 / 0.079 / - / - / -0.399 / - / -
DIS2 / - / 0 / - / - / - / - / - / 0.031 / - / -
WID / -2.046 / 0.898 / 0.313 / - / - / 0.079 / - / -1.168 / - / -0.147
WID2 / 0.319 / -0.264 / -0.106 / - / - / 0.008 / - / 0.208 / - / 0
TEMP / 0.324 / -0.017 / - / 0.036 / 0.038 / - / 0.010 / -0.396 / -0.205 / 0.115
TEMP2 / -0.029 / 0.016 / - / 0 / 0 / - / 0.002 / 0.005 / - / 0
SLOP / 2.263 / -3.347 / 1.842 / -0.248 / 0.102 / 0.036 / -0.087 / 1.083 / 0.958 / -1.047
SLOP2 / -0.354 / 0.468 / 0.274 / 0.020 / 0 / - / - / -0.059 / -0.092 / 0.148
RIVG-D / 0 / - / 0 / 0 / 0 / 0 / 0 / 0 / 0 / -
RIVG-E / 1.601 / - / -0.080 / -0.196 / -0.312 / 0.244 / -0.465 / 12.131 / 6.824 / -
RIVG-MC / 0.839 / - / 0.284 / 0.027 / -0.469 / 0.037 / -0.235 / 1.514 / -1.488 / -
RIVG-MF / 1.724 / - / -0.144 / -0.027 / -0.215 / 0.254 / -0.569 / 1.259 / 0.707 / -
RIVG-MN / 1.116 / - / 0.022 / 0.425 / 0.232 / 0.054 / -0.080 / 0.057 / -0.016 / -
RIVG-NP / 0.531 / - / 1.243 / -0.029 / -0.575 / 0.088 / -0.444 / 0.742 / -0.206 / -
RIVG-NE / -0.281 / - / -0.015 / 0.106 / -0.057 / -0.114 / -0.263 / -0.155 / -0.296 / -
RIVG-R / 1.314 / - / 0.080 / 0.144 / 0.012 / 0.163 / -0.402 / 1.955 / 0.706 / -
RIVG-SS / -0.022 / - / 0.175 / -0.422 / -0.325 / -0.218 / -0.442 / 1.528 / -0.458 / -
RIVG-UK / 0.817 / - / -0.414 / 0.038 / -0.013 / 0.183 / -0.545 / 0.632 / 0.051 / -
RIVG-WF / 1.239 / - / -0.193 / 0.357 / 0.148 / 0.152 / -0.399 / 0.754 / 0.177 / -
Mean / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0.010 / 0.055 / -0.019
s.d. / 1.722 / 2.153 / 1.332 / 0.411 / 0.361 / 0.300 / 0.396 / 0.210 / 0.240 / 0.145