Publication Abstract

Disease risks associated with the importation and release of non-native crayfish species in England and Wales

M Longshaw*, K. Bateman*, P. Stebbing*, G. Stentiford* and F. Hockley

A full histological survey of seven hundred and eighty two non-indigenous crayfish either established in riverine habitats or imported into the United Kingdom through the aquarium trade has been conducted. In addition, selected populations were subjected to further bacteriological, molecular and ultrastructural studies to characterise selected disease conditions. A total of eight species of crayfish were examined including Pacifastacus leniusculus, Orconectes virilis, Astacus leptodactylus, Cambarellus patzcuarensis, Cherax quadricarinatus, Procambarus clarkii, Procambarus fallax and Cherax peknyi. These were obtained from 18 populations established in rivers in mainland Britain, from eight pet shops illegally selling crayfish and from seven shipments of crayfish seized at point of entry. Only the established population of O. virilis was found to be negative for any infections; one shipment of P. clarkii and one aquarium held population of C. quadricarinatus were also found to contain no visible infections. Non-native crayfish were hosts to ciliates, temnocephalids, ostracods and Psorospermium infections. One shipment of P. clarkii from Singapore was infected with white spot virus (WSSV). Bacterial species isolated from crayfish included Aeromonas hydrophila, Aeromonas sobria, Citrobacter freundii, Grimontia hollisae, Hafnia alvei, Pastuerella multicida and Weeksella virosa. The majority of signal crayfish (66.5%) were negative for infection. The remaining signal crayfish were infected with at least one pathogen or commensal including an intranuclear bacilliform virus designated as Pacifastacus leniusculus bacilliform virus (PlBV) and a novel Spiroplasma sp. of the Sertoli cells of male crayfish. Low level bacterial and ciliate infections as well as commensal mites and ostracods also occurred on or in established signal crayfish. Results are discussed in relation to the enemy release hypothesis and considers the risk associated with the transboundary trade in non-indigenous crayfish as a potential source of disease to native crayfish species.

Reference:

M Longshaw*, K. Bateman*, P. Stebbing*, G. Stentiford* and F. Hockley (2012) Disease risks associated with the importation and release of non-native crayfish species in England and Wales. Aquatic Biology 16:1-15