Age-related differences in prey-handling efficiency and feeding habitat utilization of Squalius carolitertii (Cyprinidae) according to prey trait analysis

Multivariate prey trait analysis is a functional approach to understand predator-prey relationships. Here, seven macroinvertebrate ecological traits have been used for the analysis of trophic ecology of co-occurring age classes of Northern Iberian chub Squalius carolitertii, a cyprinid fish species. The present study identified several key factors in the handling efficiency and habitat utilization for feeding of S. carolitertii that may have a wider application, particularly for other cyprinid species. The results revealed a remarkable similarity in the feeding behaviour among age classes, suggesting a foraging behaviour convergence among them in both prey-handling efficiency and feeding habitat utilization. Nevertheless, some age classes showed clear preferences for particular categories of ecological trait; for example, age 1 showed a clear ability to feed on flattened prey items, whereas ages 2 and 3 were able to feed on preys with different body shape due to their general distribution in the fuzzy principal component analysis (FPCA). Finally, this study shows how multivariate approaches can complement traditional diet analyses, and the method has wide applicability across life-stages of cyprinid species.