Authors

J R Thomas¹; C Robinson²; A Ellison¹; E Matthews¹; S W Griffiths¹; S Consuegra²; J Cable¹;  ¹ Cardiff University, UK;  ² Swansea University, UK

Discussion

Parasites can play a key role during the spread of invasive, non-native species, especially when invaders transmit parasites to native species. Parasites can also influence the behaviour of invaders, which can mediate their impact and spread in invaded ecosystems. The invasive North American signal crayfish (Pacifastacus leniusculus) has caused mass mortalities of native European crayfish species, primarily through the spread of crayfish plague (Aphanomyces astaci). This oomycete pathogen is fatal to all European crayfish species, though North American crayfish are generally considered to be largely resistant carriers. Such a chronic infection, however, could affect invasive crayfish by altering their behaviour. Here, we tested the effect of crayfish plague on signal crayfish behaviour. Overall, infected crayfish spent significantly less time out of water, were less active during the day and were less likely to display an escape response when infected. In management terms, this study shows that crayfish plague affects invasive crayfish to a greater extent than previously considered, which could contribute to observed signal crayfish declines in commercially harvested stocks.