Statistical analysis
Statistically significant differences in relative abundance with regard to sampling sites and time were calculated using “metastats” in mothur, which is based on the homonymous bioinformatics program (White et al., 2009; Paulson et al., 2011). “Metastats” uses repeated t statistics and Fisher's tests on random permutations to handle sparsely-sampled features (White et al., 2009). Results were reported as a mean and standard deviation (SD). The significance level was set to P < 0.05. The P-values were adjusted with the Benjamini and Hochberg false discovery rate correction (FDR, q-value), and a q < 0.25 was considered significant (Lim et al., 2016). Furthermore, significant differences between the diversity estimators of the two groups were performed using the non-parametric Kruskal-Wallis-test followed by Mann-Whitney-test. PASW statistics 20, SPSS software (Chicago, Il., USA) was used for statistical analyses of diversity estimators.