Preliminary assessment of a
microbound diet as an Artemia replacement for mud crab, Scylla
serrata, megalopa
J. Genodepa, Ch. Zeng, P.C. Southgate-2004
Aquaculture, 236(1-4): 497-509
Abstract:
As an important step toward development of a
formulated diet for hatchery culture of the mud crab, Scylla serrata,
this paper reports on laboratory experiments to assess the potential of a
microbound diet (MBD) as a replacement for Artemia nauplii fed to
megalopal larvae of S. serrata. The effects of different proportions
of dietary MBD and Artemia on survival and moulting success of
megalopa to the crab stage were investigated. In the first experiment,
megalopae were reared communally and fed either 100% MBD, 100% Artemia
or different combinations of the two (75%:25%, 50%:50%, 25%:75%). The
experiment was terminated when all larvae had either metamorphosed or died.
Larvae fed a combination of 25% MBD and 75% Artemia consistently
showed the highest survival among all treatments throughout the experiment.
Survival of larvae fed 100% MBD was the lowest early in the experiment but
improved to become the second highest toward the end of the culture period.
Overall survival of larvae fed 100% MBD did not differ significantly from
that of larvae fed 100% Artemia. Moulting to the crab stage began on
day 7 for larvae in the treatment receiving a 50%:50% combination of MBD and
Artemia. On day 8, all larvae in treatments receiving greater than
25% MBD had some first stage crabs. Larvae fed Artemia only were the
last to moult to the juvenile crab stage, but moulting occurred
simultaneously on day 10. Because of cannibalism observed in the first
experiment, a second experiment was conducted where megalopae were reared
individually and fed either 100% Artemia or 100% MBD. Ninety percent
of larvae from both treatments successfully moulted to the crab stage.
Again, megalopae fed MBD began moulting 1 day ahead of those fed Artemia.
The results of these studies show that the MBD used contained all necessary
nutrients to sustain successful moulting of S. serrata megalopae to
the crab stage. The acceptability of MBD by S. serrata larvae
suggests significant potential for using the MBD in future experiments to
investigate larval nutritional requirements of this commercially important
crab species. Indeed, the more rapid moulting of larvae fed MBD in both
experiments suggests that the MBD may have contained certain beneficial
nutrients that were not provided by Artemia alone. The fact that no
significant differences in survival between megalopae fed 100% MBD and those
fed 100% Artemia in both communal and individual rearing experiments
suggests that total replacement of Artemia with MBD is possible for S.
serrata megalopae. This could result in substantial savings in operating
costs for S. serrata hatcheries.
(Crustacean Aquaculture Research Group, Discipline of
Aquaculture, School of Marine Biology and Aquaculture, James Cook
University, Townsville, Queensland 4811, Australia, e-mail of Ch. Zeng: Chaoshu.Zeng@jcu.edu.au)