Could salinization and invasion influence the biodiversity of aquatic invertebrates

Successful invasion in temporary aquatic ecosystems is possibly linked to a wider tolerance to environmental conditions, such as drought and salinity. We experimentally assessed the salinity tolerance (as a proxy for environmental tolerance) in invasive, Echinogammarus berilloni, and two native gammarids, Gammarus pulex and G. fossarum and the effect of infestation of Polymorphus minutus with either of the three amphipod species on salinity tolerance. The three amphipod species are found in seasonal and permanent waterways on the Paderborn plateau. These gammarids are the intermediate hosts of the acanthocephalan parasite Polymorphus minutus, which has aquatic birds as its final host. We predicted that there is high salinity tolerance in unparasitized invasive species and also this parasite increases salinity tolerance of all their intermediate hosts. Comparing natives vs. invasives we obtained the following results: Both unparasitized and parasitized E. berilloni showed significantly higher short and long-term salinity tolerance compared to both unparasitized and parasitized natives. Our results contribute to the understanding of the evolutionary ecology of invasive species and the role of increased environmental tolerance to invasion success.

Keywords:

Invasion , Salinity tolerance , Polymorphus minutus , LC50 values , Gammarids