Modeling trophic interactions and impacts of introduced icefish (Neosalanx taihuensis Chen) in three large reservoirs in the Yangtze River basin, China

Abstract

Non-native fish introductions may damage aquatic ecosystems. To assess the ecological impacts of the introduced icefish (Neosalanx taihuensis Chen), three reservoirs in a cascade, including the Shuibuya Reservoir (SBYR), which is devoid of icefish, and the Geheyan Reservoir (GHYR) and the Gaobazhou Reservoir (GBZR), which have large and small icefish populations, respectively, were selected for this study. Three mass-balance trophic models were established using the Ecopath approach. The results indicated that (1) the three ecosystems tended to depend more on the grazing food chain, possibly because the dominant fish species in three reservoirs were mainly filter feeders or planktivores; (2) the large icefish population in the GHYR decreased the overall energy transfer efficiency; (3) the ecosystem indices suggested that the GHYR ecosystem appeared to be a moderately mature system with a simple and vulnerable food web structure, and the lack of complexity was largely attributed to the large population of introduced icefish; and (4) the “mixed trophic impacts (MTI)” and niche overlap analysis indicated that the ecological impacts of icefish mainly came from predation and interspecific competition. This study demonstrates the consequence of icefish introduction to aquatic ecosystems and suggests that appropriate control of exotic fish is worth considering.