Does river channelization increase the abundance of invasive crayfish? Survey of Faxonius limosus in small Central European streams

The aim of this study was to assess whether regulated river reaches show higher numbers of the spiny cheek crayfish Faxonius limosus, a common freshwater invader in Europe. Man-made alterations of riverine habitats may increase their susceptibility to biological invasions. This phenomenon is commonly studied in the context of dam reservoirs; however, the impact of river channelization and the resulting riverine habitat homogenization on the success of invasive species are mostly lacking. Surveys were conducted in natural and channelised river stretches in five rivers of south-central Poland. General linear mixed model analysis showed that crayfish abundance is usually higher at sites located within regulated reaches. The likely reason for the detected differences in abundance of crayfish may be related to decreased food-web complexity and lack of predators in a homogenised habitat. The results suggest that the channelization of small watercourses may increase the abundance of invasive species F. limosus and its pressure on native European crayfish. However, due to limited data obtained in field, our study should be considered as a pilot one. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11356-021-12750-y.