First episode of Shell disease in Palinurus elephas (Fabricius, 1787) in Sicily

The excessive exploitation of European red spiny lobster Palinurus elephas (Fabricius, 1787), and the consequent recorded stock impoverishment in the Mediterranean Sea have induced new management policy, restocking programs, new fishing regulation activities and an increased interest in future intensive rearing protocols. In Sicily, during a growth trial on intensive rearing, an episode of Shell Disease in P. elephas occurred. Ten wild specimens of P. elephas were kept into 2 flow-tanks (2 m3), under natural photoperiod and daily fed to excess with fresh mussels.Morphometric parameters were recorded weekly in order to observe biomass increase. Six month after caught, examination of lobsters revealed changes in the tail from blistering of the ventral surface to ragged and complete loss of some sections. This pathologic condition is associated with the typical crustacean Shell disease which in P. elephas, showed the following characteristics: tail erosion, ulcerations of uropods and telson, melanisation of lesions and necrosis of the appendages. The pathology was found in 90% of specimens, but was not fatal. Samples of hemolimph and lesions pads were taken for the bacteriological assays. 198 bacterial strains were isolated from the lesion pads belonging to Listonella (Vibrio) anguillarum (50.5 %), Vibrio parahaemolyticus (27.5 %) and Vibrio alginolyticus (22 %). Furthemore, hemolimph analysed at different days was always sterile. The results indicate that the pathology was caused by different bacterial strains all belonging to the genus Vibrio, that for their chitinolytic and proteolytic enzymes are often associated with the exoskeleton lesions.