Assessing Current Fish Diversity in the Yellow River Basin by Integrating Large-Scale Barcoding and Morphological...

In recent years, fish populations in the Yellow River (YR) basin have declined sharply due to human activities. Some studies even suggest that nearly half of the native fish species in the YR have disappeared. There are also significant differences among the literature on the systematic discussion of fish species in the Yellow River Basin. The construction of a standardized and complete DNA barcode database for YR fish is urgently needed. In this study, 127 sampling points were sampled in the YR basin from 2013 to 2023, and a DNA barcode database of 3011 sequences and 110 species was constructed. A total of 124 operable taxonomic units (OTUs) were identified via four sequence-based species classification methods. The barcode and morphological results of 84 (77.1%) species remained consistent. Some species cannot be described in the literature and are assigned to unique OTUs, and some widely distributed species are also assigned multiple OTUs. These findings indicate that the fish diversity in the YR basin has been severely underestimated, and more detailed investigations and further research are needed. This study constructed the first fish DNA barcode database in the YR basin and provided new insights for the study of fish diversity in the region.