Histopathology of the chronic soft-shell syndrome in the tiger prawn Penaeus mondon

Abstract

One of the disease problems that affect the production of tiger prawn Penaeus monodon Fabricius in brackish-water ponds is the chronic soft-shell syndrome, a condition in which the prawn shell is persistently soft for several weeks. To determine the extent of damage in affected prawns, the histopathology of this syndrome was studied using light microscopy, transmission and scanning electron microscopy, and histochemical determination of calcium. Light microscopic studies of the exoskeleton of soft and normal hard-shelled prawns showed several distinct layers: an outer epicuticle, a thick exocuticle and a thinner endocuticle overlying the epidermis. The cuticular layers of the soft shell often had a rough or wrinkled surface and were usually disrupted and separated from the epidermis while those of the hard shell were generally intact and attached to the epidermis. The exocuticle and endocuticle of the hard shell were considerably thicker than those of the soft shell. Ultrastructural observations revealed the presence of a very thin membranous layer under the endocuticle. Tegumental ducts and pore canals traversed the 4 cuticular layers and were distinctly observed as pore openings on the epicutlcle surface. The epicuticle had a bilaminar and non-lamellate structure. The exocuticle had more wldely-spaced lamellae consisting of fibers arranged In a more compact pattern than in the endocutlcle Hjstochemical determination of calcium was done In exoskeleton and hepatopancreas of soft-and hard-shelled prawns. The hepatopancreas of soft-shelled prawn stained more intensely for calcium than that of the hard-shelled one. There was no great difference in calcium content of hard and soft shell, although the former stained slightly more intensely. Histopathological changes in the hepatopancreas of soft-shelled prawns were also observed.

Loose shell syndrome of farmed Penaeus monodon in India is caused by a filterable agent

“…General atrophy of tubules and reduction in the level of lipid storage in the HP cells as 169 Day LSS inoculum Control noticed in the present study has also been reported in the American lobster Homarus americanus subjected to nutritional stress (Rosemark et al 1980). Similarly, in shrimp affected by soft shell syndrome, the HP tubules were compressed, disarranged, and disrupted, and the lumen appeared to be larger because of the breakdown of secretory cells (Baticados et al 1987). …”

First incidence of loose-shell syndrome disease in the giant tiger shrimp Penaeus monodon from the brackish water ponds in Bangladesh

“…The presence of Vibrio species in shrimp grow-out ponds can be attributed to multiple etiological agents (Raja et al 2012). Several studies reported that nutritionally imbalanced shrimp feed, susceptibility to different chemical pesticides, deterioration of pond soil and water quality, and poor management practices can be responsible for LSSD in shrimps (Baticados et al 1986). We recorded 100% mortality due to intramuscularly inoculated LSSD-affected shrimp extracts in the present study.…”

“…Other symptoms include loss of appetite, weak response to stimuli, and erratic swimming (Loka et al 2012). The occurrence of LSSD in a shrimp farm is believed to be associated with such factors as nutritionally imbalanced feed, different chemical pesticides, deterioration of pond soil and water quality, and poor management practices (Baticados et al 1986). The onset of LSSD in shrimp farms can be easily detected by changes in the exoskeleton as well as in the internal organs.…”

Loose Shell Syndrome (LSS) in Litopenaeus vannamei grow-out Ponds and its Effect on Growth and Production

“…[11] observed the reason for the LSS infection due to the factors such as nutritional deficiency, pesticide pollution and poor water quality and certain management practices.…”