Abstract: Based on data collected from fish resource survey in 2016-2017, we assessed fish species diversity and the health status of Nandujiang River, Hainan Island, China. The relative importance index (IRI), Pielou uniformity index, Margalef richness index and Shannon diversity index were used to evaluate fish biodiversity. Two sets of evaluation system constructed by the fish-based biotic integrity index (IBI) were used to assess the river health status. Results showed that there were 16 dominant fish species in Nandujiang River, including Oreochromis niloticu, Aristichthys nobilis, Toxabramis houdemeri, Hemiculter leucisulus and so on. The Margalef richness index showed the same temporal trend as the Shannon diversity index, being higher in the sampling points of the source and the estuary of Nandujiang River but lower in the middle section. In contrast, the Pielou uniformity index was higher in the sampling points of the middle section but lower in the source and the river estuary. The results of fishbased biotic integrity evaluation showed that most of the historical fish were preserved in the river. The percentage indicators changed from 0.2% to 10.5%, while the change of species number ranged from 0 to 4. Among all sections of Nandujiang River, the final score of middle section was only 19 points, which was much lower than that of other sections (36-46 points). In conclusion, Nandujiang River was healthy with respect to higher fish biodiversity and biotic integrity. Among different sections of the river, the source and estuary had better biodiversity and biotic integrity than the middle section.

Key words: MaxEnt model, Cymbidium kanran, ecological niche, suitable area, prediction of potential distribution