genetic
implications in the production of rotifers in commercial finfish hatcheries
S.Dooms, K.R. Dierckens, A. Abatzopoulos, A. Triantaphyllidis, Y. Olsen,
T. De Wolf, D. Delbare, P. Bossier, P. Sorgeloos-2003
Abstract:
Success
in rotifer production is still one of the major bottlenecks in larviculture.
Periodic crashes are frequent and generally solved by an empirical approach.
Two
hypotheses are put forward in this study: 1) Mass culture of rotifers leads
to impoverishment in genetic diversity and 2) this makes the rotifer culture
more susceptible to changes in the biotic or abiotic conditions.
Samples
of cultures from commercial hatcheries will be separated into clones: these
will be characterised using 16S rDNA gene, HSP60 gene and microsatellite
markers.
Different
culture types (batch, recirculation and continuous) will be compared for
their effect on interclonal selection. The effect of the inoculation amount
on the genotypic diversity will be examined. This will give information on
the correlation between the culture method and the selection rate. The
effect of some environmental parameters (temperature, salinity and feed) on
the genotypic diversity of the rotifer culture will be assessed. These will
be kept constant during sevela culture periods on the one hand, variable
within one culture period or between culture periods on the other. The
rotifer clones may adapt to the new situation or they may crash.
In
order to document the effect of bacterial strains on interclonal selection,
mixtures of disinfected parthenogenetic eggs will be hatched and cultured
with or without addition of bacteria.
The
methodologies for resting egg production/harvest for some clones will be
fine-tuned. The advantage of resting eggs resides in the fact that
hatcheries could maintain the genetic pool of rotifer strains by
re-inoculation wil old clones.
Field
data on the genetic drift of rotifer cultures at different commercial
hatcheries will be collected.
The
results will be presented in a workshop at the end of the project.
(Ministry
of Agriculture, Centre of Agriculture Research, Sea Fisheries Department,
Ankerstraat 1, 8400 Oostende, Belgium, e-mail of K. Dierckens: kristof.dierckens@Ugent.be)