Monitoring of Vibrio parahaemolyticus in Aquaculture Ponds, Kerala, India

Qualitative and quantitative presence of the pathogenic bacterium V. parahaemolyticus in extensive and modified extensive Penaeus monodon culture systems on the southwest coast of Kerala, was monitored during three shrimp culture seasons. Annual mean V. parahaemolyticus in water constituted 6.7 %. Percentage distribution of V. parahaemolyticus in sediment was the highest during premonsoon (90.6 %) and the lowest during postmonsoon (89.4 %), with monsoon registering 90.4 %. Annual mean percentage in sediment was 90.1 %. In shrimp, V. parahaemolyticus load during the three seasons were 3.8, 2.1 and 3.1 %, with an annual mean of 3.1 %. Percentage distribution of V. parahaemolyticus in water, in modified extensive system during the three seasons were 1.9, 5.4 and 13.5 %, respectively. In the present study, both in extensive and modified extensive systems, V. parahaemolyticus registered the highest load in sediment throughout the three seasons. In both extensive and modified extensive systems V. parahaemolyticus showed an increasing trend up to the end of each culture season. In the present study, in both systems distribution of V. parahaemolyticus showed an increasing trend with increase in salinity. In extensive system, in shrimp and in modified extensive system, in water and shrimp, distribution of V. parahaemolticus was significantly negatively correlated with sand content (P less than 0.05) and positively correlated with silt (P less than 0.05).