Seasonal niche segregation of two sympatric xenocyprinid fishes

Abstract

Xenocypris microlepis (Bleeker, 1871) and Xenocypris davidi (Bleeker, 1871) are two closely related xenocyprinid species potentially subject to exploitative competition. They often coexist in many freshwater ecosystems, which offers an opportunity to analyze their relationships. The present study describes the seasonal feeding habits of age‐3 X. microlepis and X. davidi in Xin'anjiang Reservoir, located in Zhejiang, China, as determined by stable isotope analysis. Particulate organic matter (POM; 50%) and periphyton (50%) were the major items observed in the X. microlepis diet, whereas periphyton (>60%) was prevalent in the X. davidi diet. Seasonal variations were observed in the diet compositions of both xenocyprinid species. Whereas X. microlepis tended to ingest more sediment organic matter (SOM) in autumn than in spring and summer, SOM was the secondary food item for X. davidi over the three seasons. The seasonal diet shift observed in this work indicates niche segregation of the sympatric pair. The results of this study contribute to the current knowledge of seasonal trophic interactions in predator–prey systems where sympatric xenocyprinids are present.