3.6 Water quality and biodiversity assessment
To test whether Phylogenetic diversity (PD) can be used as a metrics of
Index of Biotic Integrity (IBI), the PD of each sampling site was
calculated through community data and the phylogenetic tree constructed
using sequences of mitochondrial COI gene (Table S3). The box plot and
t-test were used to compare the PD between the reference and disturbance
sites (Fig. 5). The PD values of reference sites were significantly
higher than those in disturbance sites (One-way ANOVA,
p<0.05), and there is no
overlap between reference and disturbance box in box plot.
Macroinvertebrate assemblages were utilized to calculate the biological
and diversity index. The grades of assessment in the Irtysh river were
as follows: B-IBI>2.04 represents excellent,
1.53< B-IBI>2.04 represents good,
1.02<B-IBI≤1.53 represents fair, 0.51<B-IBI≤1.02 represents poor, and
B-IBI≤0.51 represents bad. For the Ili river, the grades were as
follows: B-IBI>1.31 represents excellent,
1.01<B-IBI<1.31 represents good,
0.68<B-IBI<1.01 represents fair,
0.34<B-IBI<0.68 represents poor, and
B-IBI<0.34 represents bad. The water quality and biodiversity
of each site in the studied rivers were evaluated in Table S4. In the
Irtysh River, four of eight sites were excellent and only one site was
poor. However, in the Ili River, two of eight sites were excellent and
two sites were Bad.