Trophic niche partitioning among non-native fish species coexisting in a high Andean reservoir

Abstract

The arrival of a non-native species to a new environment threatens local biological diversity, causing instability in the functioning of the ecosystem. The adverse ecological effects caused by these species have been scarcely documented for the Magdalena basin. By studying predator-prey interactions, we characterized the trophic niche of three non-native species (Micropterus salmoides, Oncorhynchus mykiss, and Cyprinus carpio) that dominate a high Andean reservoir in the Magdalena basin. To understand whether non-native species are preying on native fish, or if they present specific feeding behaviors that facilitate their establishment in lentic environments, we evaluated the diversity of the prey they consume, their feeding strategy, and possible differences in the feeding scheme. Forty individuals were analyzed, and twenty categories of prey were identified for these species. The consumed prey corresponds to the native biota; however, no native fish were found in the stomach contents evaluated. The diversity of prey consumed is similar amongst species, however, M. salmoides behaves like an important predator, as it consumes a larger amount of prey. We observed that the variation in diet composition amongst the non-native species is different, which favors their coexistence as it reduces the competition amongst them. Analyzing the type of diet of this non-native fish is a useful tool that provides a description of some trophic interactions in this aquatic environment. Our results contribute information on the existing interactions amongst non-native species to the Magdalena basin, which is important for the development of strategies to manage and promote impact mitigation.