Combining data-driven methods and lab studies to analyse the ecology of <i>Dikerogammarus villosus</i>

The spread of aquatic invasive species is a worldwide problem. In the aquatic environment, especially exotic Crustacea are affecting biodiversity. The amphipod Dikerogammarus villosus is such an exotic species in Flanders, which is rapidly spreading and probably has a serious impact on aquatic communities. The purpose of the present study was to make use of lab results, field data and modelling techniques to investigate the potential impact of this species on other macroinvertebrates. All types of prey that were used in predator–prey experiments (Gammarus pulex, Gammarus tigrinus, Crangonyx pseudogracilis, Asellus aquaticus, Cloeon dipterum and Chironomus species) were consumed by D. villosus, especially species that were less mobile such as the Chironomus species. The presence of gravel somewhat reduced predation by providing shelter to the prey. Substrate preference experiments indicated that D. villosus preferred a stony substrate. Using decisions trees to construct habitat suitability models based on field observations, it could be concluded that D. villosus is mainly found in habitats with an artificial bank structure, a high oxygen saturation and a low conductivity, which corresponds with canals with a good chemical water quality. Moreover, a synecological classification tree, based on the abundance of the taxa present in the macroinvertebrate communities, indicated that the presence of D. villosus negatively affected the presence of the indigenous G. pulex. When the laboratory experiments and the field observations are combined, it can be concluded that D. villosus can seriously affect macroinvertebrate communities in Flanders