Brought more than twice: the complex introduction history of the red swamp crayfish into Europe

Abstract

One of the biggest challenges in understanding and managing biological invasions is the identification of the routes of introduction. This information is often incomplete because of unnoticed, unreported and, sometimes, illegal translocations. Reports on the introduction of the red swamp crayfish (Procambarus clarkii) into Europe describe that it was introduced for the first time to southern Spain (1973 and 1974) from Louisiana; from there, it rapidly spread throughout several European countries. While other importation events and pathways of introduction have been suggested in the literature, there is no evidence that these led to wild populations in Europe. Our present study suggests two additional introduction routes into Europe from non-European areas where the red swamp crayfish had previously been reported. By using mtDNA, we found a shared haplotype between the Lake Naivasha in Kenya and Western Europe, as well as another between either western United States or Asia, and Malta. These findings support historical reports found in the literature for the former case and also point towards pet trade as driver of new introductions for the latter, thus highlighting the complex introduction history of the red swamp crayfish populations in Europe.

The King's aquatic desires: 16th‐century fish and crayfish introductions into Spain

“…These patterns are compatible with the non-native status of Spanish crayfish, but not with the alternative hypothesis of a native status, and were actually implicit, though not interpreted as such, in figure 5 Austropotamobius crayfish have been introduced more than once (at least twice) and from different source areas in the Iberian Peninsula (as in Figure A1c). Similar multiple introductions have already been reported for the signal (Pacifastacus leniusculus) and red swamp (Procambarus clarkii) crayfish in Europe (Oficialdegui et al, 2020;Petrusek et al, 2017). Finally, the review by highlighted the notable underrepresentation of the Italian samples in the available genetic information (as in Figure A1d), which limits the options to frame the haplotype variability observed amongst Iberian Austropotamobius in a wider context (see Blakeslee et al, 2008 for an analogous example).…”

Inference of local invasion pathways in two invasive crayfish species displaying contrasting genetic patterns

“…Our genetic analyses suggested the occurrence of multiple invasion pathways for P . clarkii at a local scale, hence mirroring the co‐occurrence of multiple invasion pathways observed at the global scale (Oficialdegui et al., 2019, 2020). For instance, the high values observed for genetic variability metrics (notably for PA ) for some populations, combined with the very high number of detected genetic clusters, suggest that many independent introduction events involving genetically distinct sources may have occurred despite the small spatial scale (~5,000 km²), probably through the release or contaminant pathways.…”

“…In France, the first introduction is reported in South‐western France in 1976 with individuals from Spain (Laurent, 1997). Besides this introduction event, many individuals were imported from Spain and Kenya for aquaculture from the late 1970s to the early 1980s (Holdich, 1993; Oficialdegui et al., 2019, 2020). The presence of P. clarkii in our study area was first mentioned in 1995 (Changeux, 2003), that is, approximately 40–50 generations, considering two reproductions per year (Lang et al., 2021).…”

Determinants of survival and dispersal along the range expansion of a biological invasion

“…P. clarkii originates from south-central USA (Louisiana and Texas) and was introduced to Europe through both USA-to-Kenya-to-Europe and USA-to-Spain routes (Oficialdegui et al, 2019). The species is highly fecund, tolerant to a large range of environmental conditions (including drought), generally spreads rapidly once introduced either through secondary human-mediated introductions (Oficialdegui et al, 2020) or through active in-stream and overland dispersal (Cruz & Rebelo, 2007; Tréguier et al, 2018), and often has major impacts on the invaded ecosystems (Souty-Grosset et al, 2016; Twardochleb et al, 2013).…”