Are Diatom-based Indices from Europe Suitable for River Health assessment in China? A Case Study from Taizi River, Northeastern China

Aims: Diatom-based indices are widely used for river health assessment. Many such indices were originally developed in European countries based on a specific taxa list of benthic diatoms. Thus, the transferability of these indices to other rivers and geographic locations has been questioned.
Design, Place and Duration of Study: In this study, we sampled benthic diatoms in the Taizi River, a temperate river in northeastern China during May 2009 to evaluate the applicability of eight commonly used diatom-based indices for assessing the principal water quality gradient and relationship with different water chemical parameters.
Methodology: Sensitivities of the eight indices were evaluated by applying the principle component analysis (PCA), the box-plot map and multiple comparisons of the Kruskal–Wallis nonparametric test (K-W test).
Results: The results showed that all eight of the tested indices showed significant correlations with the principal contamination gradient of both nutrient enrichment and organic pollution. The contamination gradient was extracted through principal component analysis and the first three axes explained 40.19%, 18.72%, and 9.77% of the total variation, respectively.
Conclusion: Our results confirmed that the diatom-based indices did not properly reflect the current Chinese surface water quality classes. However, these indices showed consistent trends with chemical parameters that reflected general water quality condition, such as electric conductivity (EC); organic pollution, as reflected by dissolved oxygen (DO) and chemical oxygen demand (COD) and nutrient enrichment, as reflected by total nitrogen (TN) and total phosphorus (TP). The results indicated that both BDI and SHE were the most suitable diatom-based indices among the eight tested indices, although SPI, DES and ROTT were also suitable for river health assessment in the Taizi River.