Optimum time for weaning South African Scylla serrata (Forsk�l) larvae from rotifers to Artemia

Abstract

To determine the optimum time at which to wean Scylla serrata larvae from rotifers onto Artemia two experiments were conducted, approximately 1 month apart, using larvae from two different female crabs. In the first experiment, the larvae in three treatment groups, with nine replicates each, were fed rotifers for the first 8 days after hatching. Artemia were introduced on days after hatch (DAH) 0 -during the first zoeal instar (treatment R + A); on DAH 4 -during the second zoeal instar (treatment R4A); on DAH 8 -during the third zoeal instar (treatment R8A). In a control (ROT) larvae were fed with rotifers exclusively for 18 days until the completion of metamorphosis to megalopa. In the second experiment, the same four feeding schedules as in experiment 1 were used with an additional group of larvae (treatment AC) that were fed only on Artemia throughout the rearing period. Similar results were recorded in the two experiments. Larvae in treatments R + A and R4A performed significantly better than those in treatments R8A, ROT and AC. This was particularly evident when examining the proportion of zoeae which successfully completed metamorphosis to megalopa. Poor performance of larvae in treatments AC and ROT implied that rotifers are needed as a first food, but that rotifers alone do not fill the nutritional requirements of S. serrata larvae. Poor performance of larvae in treatment R8A suggested that the diet should be supplemented with Artemia before the end of the zoea 3 stage.Abbreviations: AC -only Artemia fed; DAH -days after hatch; LSI -larval stage index; Mmegalopa; R4A -Artemia introduced at day 4; R8A -Artemia introduced at day 8; R + AArtemia introduced at day 0; ROT -only rotifers fed; Z -zoea

Extension of Rotifer (Brachionus Plicatilis) Inclusions in the Larval Diets of Mud Crab, Scylla Paramamosain (Estampodor, 1949): Effects on Survival, Growth, Metamorphosis and Development Time

“…The mud crab zoeal instars do not always show synchronised moulting but can extend and overlap with next stage for approximately 1 day (Davis, Wille, Hecht & Sorgeloos, 2005b). Hence, no larval stage can be designed by a single day due to their non-synchronised moulting, it is relatively clear to depict survival by 'days of culture' rather than by individual development stage as in Table 2.…”

Ingestion ofArtemianauplii by Chinese mitten crabEriocheir sinensiszoea larvae

“…Nevertheless, Artemia nauplii with missing body parts (mostly only the head and appendages were eaten) were often observed at these stages, indicating that complete ingestion of Artemia might still be difficult and a smaller prey organism might be advantageous at early larval stages. Previous studies on brachyuran species showed that in early larval stages, rotifers should be provided, whereas from Z3 onwards, Artemia are preferred (Sulkin & Epifanio 1975; Zeng & Li 1996; Takeuchi, Satoh, Sekiya, Shimizu & Watanabe 1999; Davis et al 2005a, b). In addition, Baylon & Failaman (1997) reported that for S. serrata larvae, a combination of Artemia and rotifers resulted in a higher survival from Z1 to megalopa compared with only Artemia or rotifers.…”

“…Prey density is one of the factors that affects larval feeding success for all aquaculture species, in particular, the brachyuran species, which have a strong cannibalistic behaviour in the larval stage. In addition, prey size is likely to be critical in terms of the ability of brachyuran larvae to capture and ingest prey effectively (Sulkin & Epifanio 1975; Harvey & Epifanio 1997; Davis, Wille, Hecht & Sorgeloos 2005a, b). The influence of prey concentration on larval survival and development has been studied in several brachyuran species, such as Scylla serrata (Suprayudi, Takeuchi, Hamasaki & Hirokawa 2002; Ruscoe, Williams & Shelley 2004) and Ranina ranina (Minagawa & Murano 1993a).…”

Effect of feeding scheme and prey density on survival and development of Chinese mitten crab Eriocheir sinensis zoea larvae

“…the mud crab S. serrata (Suprayudi et al 2002), the swimming crab Portunus trituberculatus (Tekeuchi, Satoh, Sekiya, Shimizu & Watanabe 1999) and the mitten crab E. sinensis (Jiang et al 2000), which stated that the diet should be supplemented with Artemia at the Z3 stage. Thus, the Z3–Z4 stage can be identified as a critical stage in the development of E. sinensis , both from a nutritional and a prey size point of view as the larvae become more efficient and selective predators and show a strong preference for Artemia over rotifers (Davis, Wille, Hecht & Sorgeloos 2005b), beyond which the lack of suitable food organisms compromises the larval survival and development.…”