Bacteria of subclass γ-Proteobacteria associated with commercial Argopecten purpuratus
(Lamark, 1819) hatcheries in Chile
M.A. Jorquera, M. Lody, Y. Leyton, C. Riquelme-2004
Aquaculture, 236(1-4): 37-51
Abstract:
The management of bacterial loading in intensive
aquaculture systems is often a key factor in the success of larval cultures,
particularly in molluscan hatcheries. Vibrio spp. have often been
cited as affecting scallop larvae cultures. Bacteriological studies
employing emergent molecular methods may now be of use in molluscan
hatcheries to monitor the abundance of total and non-culturable Vibrio
spp. In this study, the fluorescence in situ hybridization (FISH) technique
with 16S rRNA-targeted oligonucleotide probes was used to quantify the
presence of γ -Proteobacteria and Vibrio spp. in the bacterioplankton
associated to mass larval cultures in six commercial hatcheries in two
geographic regions of northern Chile. Results showed an average of 58%
(Region III) and 38% (Region IV) of total cell counts could be detected by
hybridization by using probe for domain Eubacteria. Use of the probe for γ
-Proteobacteria showed averages between 21% and 28% in these regions, and
use of the probe for Vibrio spp. detected percentage between 0.6% and
17%. Direct counts by fluorescence compared with viable plate counts
suggested low culturability of the bacterioplankton. Results obtained from
the different sampling areas did not reveal a characteristic pattern for
each geographic region, nor by culture company. However, some differences
were noted between companies with healthy larval cultures and one company
which was experiencing mass larval mortalities, emphasizing the relevance of
the bacterioplankton in scallop cultures.
(Laboratorio de Ecología Microbiana,
Departamento de Acuicultura, Facultad de Recursos del Mar, Universidad de
Antofagasta, Av. Jaime
Guzman s/n Casilla 170, Antofagasta, Chile, e-mail of C. Riquelme: criquelme@uantof.cl)