Impact of native and invasive cyclopoid predators in relation to the diversity of the zooplankton community

Abstract

Abstract The ecological impact of invasive species may be less in communities with high species diversity. We hypothesized that the feeding rates of an invasive copepod would be unaffected by high species diversity of prey in the medium as compared with a native species which would have reduced feeding rates under similar conditions. The biotic resistance to prey consumption was evaluated by testing consumption rate of the invasive species: Mesocyclops pehpeiensis and the native species: Mesocyclops longisetus curvatus, Acanthocyclops americanus, Eucyclops sp. and Microcyclops dubitabilis separately exposed to two treatments: high diversity with 13 prey species (rotifers and microcrustaceans) and low diversity with three prey species (determined on the basis of previous studies on zooplankton diversity in Mexican water bodies). We also tested the prey preference index of M. pehpeiensis in the absence and presence of the native copepod M. longisetus curvatus. M. pehpeiensis consumed the same number of prey in both treatments, regardless of high or low diversity conditions, whereas the four native species consumed less prey in the high diversity than the low diversity treatments. High community diversity may not represent an obstacle to the successful establishment of the invasive exotic copepod M. pehpeiensis.