Distribution of luminous bacteria in semi-intensive penaeid shrimp hatcheries of Tamil Nadu, India
T. J. Abraham, R. Palaniappan-2004
Aquaculture, 232(1-4): 81-90
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<0.05)
increase in the mean total viable counts (TVC) from eggs (log 4.92±0.16/g)
to post-larvae (log 7.00±0.55/g) was observed; while the mean luminous
bacterial counts (LBC) showed an increase from eggs (log <2.00/g) to
mysis (log 5.34±0.93/g) and decreased thereafter (log 4.54±1.22/g
post-larvae). Luminous bacteria were undetectable on eggs but were present
in low numbers in spawning tank water, introduced by the brood stock during
spawning. Gut contents of brood stock and adult shrimp contained the highest
number of luminous bacteria (log 7.38±0.49/g). 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.
(Fisheries College and Research Institute, Tamil Nadu
Veterinary and Animal Sciences University, Tuticorin 628 008, Tamil Nadu,
India, e-mail: abrahamtj@vsnl.net)