Statistical analyses employed Stati

Statistical analyses employed Statistica 9.0 (StatSoft, 2009). The
following analyses were performed: the Student t-test for independent
samples, evaluation of statistically significant differences in
the abundance of systematic groups of organisms in traps of different
ages (the paired t-test was not possible), and Spearman’s rank
correlations to check the correlation between the abundance of the protozoa Paramecium bursaria and the number of animals and their
remains in the traps. The pH values were not transformed.