Characterization of chitinolytic bacteria and histological aspects of Shell Disease Syndrome in European spiny lobsters (Palinurus elephas) (Fabricius 1787).
The present research reports the first description of Shell Disease Syndrome in European spiny lobsters Palinurus elephas (Fabricius 1787), which occurred in an experimental aquaculture facility in Sicily (Italy). Both bacterial characterization and histopathological examination of the exoskeleton at site of lesions was carried out. Infected specimens showed tail fan erosions, and in one case uropod ulceration and complete loss of periods. Identified species included: Listonella anguillarum 50.5%, Vibrio parahaemolyticus 27.5% and Vibrio alginolyticus 22%. Microscopic evaluation of lesions indicate the presence of inflammatory responses, which include melanization and pseudomembrane formation, similar to those described for other crustaceans affected by SDS.
Carapace repair in the green crab, Carcinus maenas (L.)
Formation of a circular hole 8–10 mm in diameter in the calcified layers of the carapace from crabs in stage C4 of the molt cycle stimulates the tissue under and adjacent to the injury to deposit a unique calcified cuticular material below the intact membranous layer. Deposition was followed for 69 days using light microscopic histology, histochemistry, and scanning electron microscopy. Quantitative analyses of CaCO3 were conducted using atomic absorption spectrophotometry and Gran titration. Spatial distribution of CaCO3 was determined with X‐radiography. A scab is formed by day two under the injury. At four days the epithelium changes from squamous to columnar and deposits a PAS‐positive layer with an irregular lamellar fine structure, followed by highly organized lamellae structurally similar to normal exocuticle. Histochemically, however, these lamellae resemble normal endocuticle. CaCO3 is evident external to the outermost lamellae by day eleven as a fused mass of aragonite granules. The lamellar region calcifies proximally from the outer surface and is amorphous CaCO3. Repair cuticle is approximately 20%CaCO3 by weight.
Disease problems of prawns in recirculation systems in the U.K.
Abstract Prawn diseases encountered by the authors during research programmes on prawn cultivation are described and discussed. A variety of seawater penaeid species, the freshwater caridean Macrobrachium rosenbergii, and the seawater caridean Palaemon serratus were affected. Poor husbandry, in terms of holding tank design, water quality and/or inadequate nutrition, is often the major factor precipitating prawn disease. Attention to husbandry techniques and the routine monitoring of water quality are of paramount importance in the prevention of disease outbreaks. The significance of disease to prawn cultivation, either as a direct cause of mortalities or as a limitation to market sale, is highlighted.