Preliminary disease investigations on white-clawed crayfish Austropotamobius pallipes from streams of Northern Italy.

A total of 99 live and 3 dead white-clawed crayfish Austropotamobius pallipes were collected during the summer-autumn 2003 in one creek of Emilia Romagna and four watercourses of Friuli Venezia Giulia in Northern Italy for experimental breeding and health status monitoring. Fifty-one animals coming from Bidente river were maintained in tanks for breeding, reproduction and restocking, while 30 other specimens (27 living and 3 dead) were examined in the laboratory to evaluate their health status. Parasitological surveys were carried out on gills; mycological investigations on exoskeleton, walking legs and cuticle of abdomen; bacteriological examinations of inoculations from the haemolymph and histopathological analysis on full sections of cephalothoraxes and sections of abdomen. In the gill-chambers, the gill filaments and exoskeleton were observed for ectocommensal peritrich protozoans Epystilis sp. and Cothurnia sieboldii. In crayfish sampled in four creeks Branchiobdella italica, B. astaci and B. parasita were isolated. Hyaline and dematiaceous hyphomycetes were frequently observed and Fusarium sp. and Saprolegnia sp. were isolated from cuticular lesions. Mortalities occurred in two tanks, respectively after 2 and 4 weeks, in adult crayfish utilized for breeding, with about 23,5% cumulative mortalities. In both cases the crayfish were weak, anorexic and lethargic. Respectively four and eight moribund samples coming from the two breeding tanks, in which mortalities occurred, were submitted to investigations. In the first case the mortalities were attributed to Thelohania-like organism and in second case the mortalities were associated with enteric bacteria. Bacterial lesions were observed in the dead crayfish found in Chiarò and Bidente River and heavy damage of the gills in the presence of branchiobdellid cocoons was observed on crayfish dead in Orvenco creek.