Genodepa, Jerome, Zeng, Chaoshu, and Southgate, Paul C. (2004) Preliminary assessment of a microbound diet as an Artemia replacement for mud crab, Scylla serrata, megalopa. Aquaculture, 236 (1-4). pp. 497-509.

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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.

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