The invasive crayfish Faxonius immunis causes the collapse of macroinvertebrate communities in Central European ponds

Abstract

The invasive crayfish Faxonius immunis is regarded as a threat to amphibians and macroinvertebrates in the Upper Rhine Valley, Germany, eradicating macrophytes and establishing high-density populations in stagnant waters. This study investigates the macroinvertebrate community structure of five conservation ponds south of Karlsruhe, Germany, to identify effects caused by this invasive crayfish. Two of the ponds had a high population density of F. immunis, two were expected to have lower crayfish densities as they had been habitat modified with gravelled water beds as a crayfish management approach, and one pond was known to be free of crayfish but contained fish. The macroinvertebrate communities were analyzed considering their species richness and composition. The relative density of F. immunis within the samples was regarded as a representative indicator for crayfish population density and tested for its influence on the ordination along with habitat composition and abiotic factors using distance-based redundancy analysis. F. immunis was identified as a driving factor of the macroinvertebrate communities of sampled ponds. Additionally, this study indicates that gravelling ground beds as a management method for invasive burrowing crayfish species does not significantly influence the community composition but can minimize indirect effects caused by F. immunis.

Multiple invasions and predation: The impact of the crayfish Cherax quadricarinatus on invasive and native snails

“…Herrmann et al. ( 2022 ) indeed correlated the collapse of mollusks populations of several species, including endangered ones, in Germany, in the 7 years following the introduction of the invasive crayfish F. immunis . Considering these alarming observations and the relatively low richness of the Martinique freshwater ecosystems (i.e., not only 11 native mollusks species, but also 21 native fish and 13 native decapods species, some of which may serve as prey for C. quadricarinatus ) (Delannoye et al., 2015 ; Lim et al., 2002 ), there is an urgent need to monitor the dynamics of redclaw crayfish.…”

“…David, unpublished data). Crayfish are indeed known as snail predators (Herrmann et al, 2022;Hofkin et al, 1992;Souty-Grosset et al, 2016), sometimes strongly driving down local populations (e.g., the crayfish Faxonius immunis in several German populations in a few years; Herrmann et al, 2022). Moreover, Monde et al (2017) have documented efficient consumption of M. tuberculata by C. quadricarinatus under experimental conditions.…”

“…An iconic example is the Nile perch which strongly depressed the dynamics of numerous cichlid species in large African lakes (Aloo et al., 2017 ; Lowe et al., 2000 ). Several crayfish species are also among the invaders with strong impacts, able to feed on mollusks (Haubrock et al., 2021 ; Herrmann et al., 2022 ; Sanders & Mills, 2022 ), other benthic invertebrates (shrimps, insect larvae; Ercoli et al., 2015 ; Mathers et al., 2020 ; Twardochleb et al., 2013 ), and macrophytes (Gherardi & Acquistapace, 2007 ; Souty‐Grosset et al., 2016 ).…”

“…Its impact on local communities has not been studied, but its spread temporally coincides with an apparent decline of Thiarid populations in some rivers (P. Jarne & P. David, unpublished data). Crayfish are indeed known as snail predators (Herrmann et al., 2022 ; Hofkin et al., 1992 ; Souty‐Grosset et al., 2016 ), sometimes strongly driving down local populations (e.g., the crayfish Faxonius immunis in several German populations in a few years; Herrmann et al., 2022 ). Moreover, Monde et al.…”