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Table 2 Variation partitioning by partial canonical correspondence analysis (CCA) of fish distribution explained by three groups of environmental variables, geographical (Geo: altitude, latitude, longitude), hydromorphologic (Hydr: depth, surface) and eutrophication (Eutr: alkalinity, conductivity, total phosphorus, chlorophyll a)

From: Natural and anthropogenic driving forces as key elements in the Lower Danube Basin–South-Eastern Carpathians–North-Western Black Sea coast area lakes: a broken stepping stones for fish in a climatic change scenario?

RunResponderEnvironmental variablesCovariableTotal inertia% Variation
Total effect: all environmental variables
 SpeciesAll groups1.397 81.0
Partial effect 1Combination: Eutr and Geo and Hydro
1SpeciesEutrGeo and Hydro0.4251.39724.64
2SpeciesGeo and Hydro0.972 56.36
3SpeciesGeo and HydroEutr0.6471.39737.51
4SpeciesEutr0.750 43.49
Joint effect: Eutr ↔ Geo and Hydro = 0.972–0.647 = 0.750–0.425 = 0.32518.84
Partial effect 2Combination: Geo and Eutr and Hydro
1SpeciesGeoEutr and Hydro0.4341.39625.18
2SpeciesEutr and Hydro0.962 55.82
3SpeciesEutr and HydroGeo0.6221.39736.06
4SpeciesGeo0.775 44.94
Joint effect: Geo ↔ Eutr and Hydro = 0.962–0.622 = 0.775–0.434 = 0.34019.71
Partial effect 3Combination: Hydro and Geo and Eutr
1SpeciesHydroGeo and Eutr0.2071.39712.00
2SpeciesGeo and Eutr1.190 69.00
3SpeciesGeo and EutrHydro1.1591.39767.20
4SpeciesHydro0.238 13.80
Joint effect: Hydro ↔ Geo and Eutr  =  1.190–1.159 = 0.238–0.207 = 0.0311.80
  1. The total inertia used here is the sum of all canonical eigenvalues. The sum of all eigenvalues in a correspondence analysis of the species matrix is 1.397. Thus, the total percentage of the total variation of bug species matrix for each step is: total inertia 100/1.397