Abstract: The cause of mass mortality of Portunus pelagicus larvae reared in a hatchery system was investigated. The gut content of 180 female crabs and egg specimen of 24 female were studied for pathogenic microbes. The gut of female crabs were harboring fish pathogenic bacteria includes Staphylococcus epidermidis, Vibrio harveyi, Vibrio parahaemolyticus, Micrococcus luteus and Pseudoalteromonas piscicida and eggs were found associated with fish pathogens include Vibrio harveyi, Micrococcus luteus and Pseudoalteromonas piscicida. A causative transmitting pathogen V. harveyi through the feces of adult female crab and responsible for heavy mortality during larval rearing was determined by examining samples associated with the gut, hatching tanks, eggs, larvae rearing tanks, live and dead larvae of P. pelagicus. All isolates were identified by 16S rRNA gene sequencing. Vibrio harveyi was the major pathogen associated with all sources brought under study. Larvae were found to harbor a higher number of bacteria than larvae rearing tank. Experimental challenges with various doses indicated that the V. harveyi isolates were highly pathogenic. Doses 105 cfu mL-1 produced upto 96.67% mortality and 106 cfu mL-1 resulted in 100% mortality within 24 h post challenge. The differences among various doses of pathogen were statistically significant (p<0.05). The presence of these pathogens in P. pelagicus beyond the consequence for larval rearing is of epidemiological and health significance to humans.
A.D. Talpur, A.J. Memon, M.I. Khan, M. Ikhwanuddin, M.M. Danish Daniel and A.B. Abol-Munafi, 2011. A Novel of Gut Pathogenic Bacteria of Blue Swimming Crab Portunus pelagicus (Linneaus, 1758) and Pathogenicity of Vibrio harveyi a Transmission Agent in Larval Culture under Hatchery Conditions. Research Journal of Applied Sciences, 6: 116-127.