T. Jawahar Abraham

Distribution of luminous bacteria in semi-intensive penaeid shrimp hatcheries of Tamil Nadu, India

Abstract The distribution and species composition of luminous bacteria in commercial penaeid shrimp hatcheries were studied. Luminous bacteria were found in the larval rearing tanks in considerable numbers ranging from log 0.70 to log 5.41/ml. A gradual but significant ( P Artemia nauplii, a preferential feed for both mysis and post-larvae, harboured and introduced a considerable population of luminous bacteria (log 2.44±0.42/g) into the mysis and post-larval rearing tanks. Qualitatively, Vibrio harveyi was isolated as a dominant luminous species (94.05%) followed by Vibrio orientalis (5.41%). Vibrio splendidus biotype 1 was isolated only from source water. The swab samples of biofilm from the inner surfaces of poly vinyl chloride (PVC) water distribution pipes, aeration pipes and emptied larval tank walls contained V. harveyi and apparently served as a continuous reservoir of luminous bacteria. The observation on the presence of V. harveyi (97.30%) and V. orientalis (2.70%) in shrimp gut contents evinced that the primary source of these bacteria in a shrimp hatchery was the faecal matter from brood stock, possibly at the time of spawning.