Invasion on the doorstep: will the Carpathians remain free from the spiny cheek crayfish Faxonius limosus (Rafinesque, 1817)?

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

“…Our study suggests that despite F. limosus being present in both natural and regulated river habitats, watercourse management may have an impact on its abundance and, presumably, the impact of crayfish on local ecosystems. This is important in the context of observations of several authors (Holdich and Black 2006 ; Chucholl 2016 ; Bonk and Bobrek 2020 ) who showed that F. limosus does not ingress into the smallest headwater streams, which are often a refuge of native crayfish (i.e. Astacus astacus is present in the Sanica and Radna rivers within the area of our study, M. Bonk, unpublished data).…”

“…In general, F. limosus avoids small headwater streams (Chucholl 2016 ), which may be related to water temperature (Bonk and Bobrek 2020 ); thus, some of the described sections probably lie near the upper limit of the colonization ability of streams by this species. However, temperature is probably not a major reason for differences in crayfish abundance as in each locality, both regulated and unregulated sections were placed at approximately the same distance from the springs; also, the temperature in one type of section may be related to the temperature within the other due to the short distances between them.…”

Damselfly eggs alter their development rate in the presence of an invasive alien cue but not a native predator cue

“…Based on a meta-analysis, Anton et al (2020) report that on average, 200 generations are necessary for prey to recognize new predators. The studied damselflies and invasive alien spinycheek crayfish have co-occurred in the sampling area through the last 50 years (Bonk & Bobrek, 2020;Śmietana, 2011). Assuming a maximum of two generations per year, I. elegans is still far from 200 generations.…”

“…Damselfly eggs and larvae are prey for aquatic invertebrate and vertebrate predators (Corbet, 1999). We used three predators to impose nonconsumptive effects on damselfly eggs: perch ( Perca fluviatilis ), which is native and co‐occurs with I. elegans eggs and larvae; spinycheek crayfish ( Orconectes limosus ), an invasive alien predator that has co‐occurred with the damselfly for at least 50 years (Bonk & Bobrek, 2020; Śmietana, 2011); and signal crayfish ( Pacifastacus leniusculus ), an invasive alien predator that has not occurred in areas where we collected damselflies (Dobrzycka‐Krahel et al., 2017). Signal crayfish are expected to invade the damselfly sampling site in the near future; in 2020, new sites were found ca.…”