Table 6

Significance of the effects of environmental variables on zooplankton abundance based on multiple regression (stepwise procedure) with the following dependent variables: Ntot, Nr, Ncl, Ncp − total zooplankton, Rotifera, Cladocera, and Copepoda density, respectively; Btot, Br, Bcl, Bcp − total zooplankton, Rotifera, Cladocera, and Copepoda biomass, respectively. The independent variables included in the model were: Q − water flow; DO − dissolved oxygen; H₂S − hydrogen sulphide; SO₄ – sulphate; PO4-P − soluble reactive phosphorus. Probability levels of t-values for coefficients are denoted as follows: *P  < 0.05, **P < 0.01; ^1,2 site number.