Crayfish plague affects juvenile survival and adult behaviour of invasive signal crayfish

Abstract

The spread of invasive, non-native species is a key threat to biodiversity. Parasites can play a significant role by influencing their invasive host's survival or behaviour, which can subsequently alter invasion dynamics. The North American signal crayfish (Pacifastacus leniusculus) is a known carrier of Aphanomyces astaci, an oomycete pathogen that is the causative agent of crayfish plague and fatal to European crayfish species, whereas North American species are considered to be largely resistant. There is some evidence, however, that North American species, can also succumb to crayfish plague, though how A. astaci affects such ‘reservoir hosts’ is rarely considered. Here, we tested the impact of A. astaci infection on signal crayfish, by assessing juvenile survival and adult behaviour following exposure to A. astaci zoospores. Juvenile signal crayfish suffered high mortality 4-weeks post-hatching, but not as older juveniles. Furthermore, adult signal crayfish with high-infection levels displayed altered behaviours, being less likely to leave the water, explore terrestrial areas and exhibit escape responses. Overall, we reveal that A. astaci infection affects signal crayfish to a much greater extent than previously considered, which may not only have direct consequences for invasions, but could substantially affect commercially harvested signal crayfish stocks worldwide.

Disturbance in invasion? Idiopathic necrotizing hepatopancreatitis in the signal crayfish Pacifastacus leniusculus (Dana, 1852) in Croatia

“…Emerging wildlife diseases usually occur due to movement of pathogens or ecosystem alterations of either anthropogenic or natural origin, and may threaten local biodiversity (Cunningham et al, 2012;Daszak et al, 2000;Schmeller et al, 2020). In the case of successful invaders like the signal crayfish, such diseases may also affect invasion success and even alleviate its negative effects on the ecosystem (Fincham et al, 2019;Thomas et al, 2020). In this study, we recorded the extensive manifestation of histopathological lesions in hepatopancreas of the majority of examined signal crayfish individuals along its entire invasion range in the Korana River.…”

Money Kills Native Ecosystems: European Crayfish as an Example

“…However, susceptible crayfish and A. astaci seemed to have created a novel and complex relationship, with evidence for a rapid co-evolution of native crayfish and A. astaci (Jussila et al, 2015(Jussila et al, , 2021a. Moreover, the alien crayfish in their newly invaded biogeographic regions in Europe show increased susceptibility with even population collapses reported (e.g., Jussila et al, 2014a;Sandström et al, 2014;Thomas et al, 2020). As a result, among crayfish stocks in Europe, the resistance of both native European and alien crayfish against the crayfish plague has changed, as has the virulence of the disease agent A. astaci (e.g., Jussila et al, 2015).…”

“…Laboratory scale infection studies have revealed significant virulence differences among and within A. astaci haplogroups and even the existence of very low virulent strains (e.g., Makkonen et al, 2012;Jussila et al, 2017;Francesconi et al, 2021). The invasive crayfish, especially P. leniusculus, have lately been shown to be susceptible to A. astaci, which points to the high virulence of the infecting A. astaci haplogroup B and possibly a lowered resistance of P. leniusculus toward A. astaci (Aydin et al, 2014;Jussila et al, 2014a;Thomas et al, 2020). Laboratory experiments have demonstrated that the A. astaci of haplogroup B, although highly virulent, is also capable of exhibiting a significant but narrow range of virulence variation (Jussila et al, 2013a).…”

“…Another twisted argument in favor of alien invasive species is the claim that introduced North American crayfish species P. leniusculus, P. clarkii, or F. limosus are immune against A. astaci infection, a definition that is commonly used when justifying the introduction and spreading for example alien P. leniusculus in Europe (e.g., Bohman et al, 2006;Jussila et al, 2015). However, it has been shown directly in laboratory tests (Unestam and Weiss, 1970;Persson and Söderhäll, 1983;Vey et al, 1983) and indirectly from wild stock observations, that these alien species, particularly P. leniusculus, can be quite often susceptible to A. astaci infection and stock collapses due the crayfish plague epidemics have been reported (Jussila et al, 2014a;Sandström et al, 2014;Martín-Torrijos et al, 2019;Thomas et al, 2020). This, again, is one example on how decision makers aim to justify their considerations of the first alien species introductions, and how difficult it is to get the novel message of state of the art facts recognized, even though being supported by reliable data.…”

The redclaw crayfish: A prominent aquaculture species with invasive potential in tropical and subtropical biodiversity hotspots

“…Crayfish (Decapoda: Astacidea) are a diverse taxonomic group of freshwater crustaceans (Crandall & De Grave 2017; Taylor et al . 2019), containing both critically endangered endemic species (Taylor et al . 2007; Crandall & Buhay 2008; Bláha et al .…”