Abstract: To investigate the characteristics of benthic diatom communities and changes in water quality in Jiulingshan National Nature Reserve during summer, a survey was conducted at 56 sampling sites in the stream waters of the Baofeng Station (BF), Daqishan Station (DQ), Zaodu Station (ZD), and Qingshan Station (QS) in July and August 2022. Physicochemical parameters of the water and the composition of benthic diatom communities were assessed. Diversity and diatom indices were used to assess water quality. A total of 77 species from 25 genera of benthic diatoms were identified at the four stations. A total of 13 genera were identified as dominant ones, with 9, 6, 4, and 6 dominant genera being observed at the BF, DQ, ZD, and QS stations, respectively. The main dominant genera included Navicula, Gomphonema, and Cocconeis. The total abundance of benthic diatoms in BF, DQ, ZD, and QS stations ranged from 0.03×10⁵ to 20.27×10⁵, 0.05×10⁵ to 7.96×10⁵, 0 to 14.65×10⁵, and 0 to 12.85×10⁵ ind·cm^-2, respectively. The biomass of benthic diatoms in these stations ranged from 0.02 to 8.11, 0.01 to 3.44, 0 to 5.86, and 0 to 5.14 mg·cm^-2, respectively. The total abundance and biomass of benthic diatoms were lower in DQ than in other stations, and the highest at the BF station. The Margalef, Pielou, and Shannon indices were higher at the QS station. Based on the results of diversity index and generic index of diatom (GI), water quality in Jiulingshan National Nature Reserve was generally classified as clean-moderately polluted. The water quality at QS was the best and that at BF was the worst. Multiple linear regression analysis showed that total phosphorus, total nitrogen, ammonium nitrogen, and altitude had strong impacts on benthic diatom communities. Our results provide valuable information for the conservation and maintenance of aquatic ecological environment in Jiulingshan National Nature Reserve.

Key words: Jiulingshan, benthic diatoms, diversity index, generic index of diatom, water quality