Distribution of simulated multiple-site dissimilarity metrics for overall, native, and non-native fish assemblages in the 2000s (solid lines) and the 2010s (dash lines). Overall dissimilarities (grey), as well as turnover (blue) and nestedness (green) components, were demonstrated in different colors. Frequency distributions were estimated by bootstrapping procedure (N = 100, with replacement) of seven sites per permutation to calculate multiple-site dissimilarities (denotes: ***: p < 0.001; **: 0.001 ≤ p < 0.01; *: 0.01 ≤ p < 0.05; n.s. = no significance: p ≥ 0.05, based on PERMANOVA tests with 9,999 permutations).