Fish Community Structure and Ecological Niche of the Major Fish Species in Nanwan Reservoir

LUN Feng; TAN Chenxi; SU Chaoqun; YANG Tiezhu; MA Yuanye; LI Zheng

doi:10.15933/j.cnki.1004-3268.2025.08.016

Abstract：To understand the fish community structure characteristics and interspecific relationships of major fish species in Nanwan Reservoir,fish resource surveys were conducted in November 2022(autumn)and May 2023(spring).Community composition,fish diversity,and spatiotemporal niche characteristics[including niche width index(Bi)and overlap index(Qik)]were analyzed.The results showed that a total of 1 903 fish were captured in the two surveys,belonging to 24 species,22 genera,6 families,and 4 orders.Comprehensive analysis showed that in Nanwan Reservoir Hemiculter leucisculus,Toxabramis swinhonis,and Xenocypris davidi was the dominant species.Based on the PINKAS relative importance index(IRI),a total of 10 major fish species were identified.There were spatio-temporal variations in fish diversity in the Nanwan Reservoir.The Margalef species richness index in spring(2.78)was slightly higher than that in autumn(2.67),whereas the Shannon-wiener diversity index,Pielou evenness index and Simpson dominance index in autumn were significantly higher than in spring,and the fish species diversity was significantly higher in the central reservoir area.Spatio-temporal niche analysis revealed that Chanodichthys dabryi(1.254),X.davidi(1.073),and Sarcocheilichthys sciistius(1.024)exhibited moderate niche width index,while other species showed low niche width index.Among spatiotemporal niche overlap index,18 species pairs(40%of total pairs)showed high overlap index(Qik>0.6),and 11 pairs(24.4%)exhibited low overlap index(Qik<0.3).The highest spatiotemporal overlap occurred between Pseudorasbora parva and Carassius auratus(0.922),while P.parva and T.swinhonis,despite having similar ecological habits,displayed low overlap index(0.249).In conclusion,the dominant fish species with significant differences in feeding habits and living water layers in the Nanwan Reservoir show a more stable community structure;fish species with similar feeding habits but different living spaces have higher spatial and temporal overlap index.Fish species with similar feeding habits and living water layers may have reduced spatial and temporal overlap index due to niche competition,accompanied by significant population fluctuations.