Pathological investigations on crayfish (Procambarus clarkii, Girard 1852) from canals in the Po valley.

A population of allochthonous crayfish Procambarus clarkii (Girard, 1852) was studied to observe the presence and effects of diseases and epibionts. A total of 268 animals were analysed during a 4 – year period: 100, 72, 54 and 42 specimens in 1998, 1999, 2001 and 2002, respectively. The samples were collected from canals and ditches of the Consortium of the Reclamation Renana (CBR), in the province of Bologna. The study regarded mycological, parasitological, bacteriological and histopathological investigations. During the mycological investigations: Aphanomyces astaci, Fusarium sp., Dictyuchus sp., Trichoderma viridae, Rhizopus sp., Drechslera sp., Mucor sp., Cladosporium sp., Penicillium sp., Alternaria sp., Rhodotorula sp., Cryptococcus laurentii, Aspergillus candidum, Phoma sp. and Gliocladium sp. were isolated. During the parasitological investigations: Epistylis sp., Cothurnia sp. and ciliated protozoans were isolated. One commensal Nematode in the gills and three intestinal Nematodes whose determination is still under study were found. The bacteriological examinations of crayfish which dead during the transport and were kept in laboratory, led to the isolation of Aeromonas sobria, Citrobacter freundii and Pseudomonas sp. Histopathological surveys are described.