FISH COMMUNITY PATTERN AND DIVERSITY AFFECTED BY WATER AND SEDIMENT REGULATION IN SHANDONG SECTION OF THE YELLOW RIVER

To practice the ecological conservation and high-quality development of the Yellow River Basin, the species composition, biomass, dominant species, biodiversity and environmental factors were surveyed at 4 sampling sections in Shandong section of the Yellow River before and after water and sediment regulation (WSR) in June and July by multi-mesh composite gillnets and ground cage nets. The results showed that 59 fish species, belonging to 9 orders and 19 families were collected in Shandong section. The dominant species changed non-significant before and after water diversion. However, there were significant differences between Shannon-wiener index (0.01<P<0.05) and the Margalef index, but Pielou index showed no significant difference (P>0.05). Cluster analysis showed that all sections could be divided into four groups when the similarity level was 60%, among which the Dong’e (AW2) section displayed strong difference after WSR. Furthermore, RDA analysis indicated that velocity and TP were the main factors affecting community structure. Based on the results, we found that the species number and Shannon-Wiener index significant increased in Shandong section of the Yellow River over the past decade. This positive trend was attributed to fish following the water and sediment regulation and residing in the area between Dongping Lake and the Yellow River, characterized by slow flowing water, abundant baits, and low sedimentcontent. Additionally, the stabilization and normalization of the Yellow River runoff had transformed previously dry section into habitats rich in water, effectively forming a river inlet for fish. Moreover, the irregular opening of the sluice in Dongping Lake not only enriched the bait species in Pangkou Inlet, but also provided a path for fish, such as Coilia nasus, to enter the Yellow River. In view of the fish community structure and diversity in Shandong section of the Yellow River, this study recommends implementing environmental restoration in Pangkou Inlet, enhancing the protection of rare species, conducting research on endemic species, maintaining stability of the Yellow River runoff and optimizing flow management in Shandong section of the Yellow River to ensure a more scientifically guided approach.