Results of gradient forest for maximal water temperature (Tempmax, left column) and dissolved organic carbon (DOC, right column, log scale). The specific cumulative importance indicates the locations of potential thresholds in the responses of fish species to the gradients (note the offset of the y-axis for Salmo trutta). The BPUE of four species are shown as examples: Salmo trutta and Phoxinus phoxinus for Tempmax and, Barbatula barbatula and Perca fluvatilis for DOC. Plain lines are local regressions on strictly positive BPUE values and dashed lines are probabilities of presence along the gradients.