Effects of Artemia enriched with eicosapentaenoic and
docosahexaenoic acid on survival and occurrence of molting failure in
megalop larvae of the mud crab Scylla serrata
M.A.
Suprayudi, T. Takeuchi, K. Hamasaki-2004
Fisheries
Science,
70(4): 650-658
Abstract:
The
present study was conducted to investigate the effect of eicosapentaenoic
acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) on the survival
and the occurrence of molting failure to megalops of mud crab Scylla
serrata larvae fed enriched Artemia. Survival rate, intermolt
period, carapace width at the first crab stage, ratio of chela to carapace
length at the fifth zoeal stage and the occurrence of molting failure to
megalops were observed. Mud crab larvae were reared in 1-L plastic beakers
and fed with Artemia enriched at five different levels of EPA (0.31%
to 1.36% EPA; referred to as E25, E50, E75 and E100) or four different
levels of DHA (0.75 - 0.95%
EPA and 0.49 - 1.38%
DHA; referred to as D25, D50, D75 and D100). As a negative control, larvae
were fed Artemia enriched with oleic acid (OA). Mud crab larvae fed Artemia
containing low (0.41 - 0.45%
EPA and trace DHA) or high (1.36% and 0.95% EPA and 0.16% and 1.38% DHA)
amounts of EPA and DHA showed a significantly lower survival rate and
prolonged intermolt period (P < 0.05). Moreover, a high
frequency of molting failure to the megalops stage (34 and 33%) occurs
coincident with a high chela to carapace length ratio (43 and 44%) in mud
crab larvae fed high amounts of EPA and DHA (E100 and D100), suggesting that
both of these treatments contain EPA and DHA in excess. These results
indicate that during Artemia feeding, EPA and DHA content should be
adjusted to 0.71 - 0.87%
and 0.49 - 0.72%
for maintaining a high survival, accelerating the intermolt period, and
producing larger carapace width in the first crab stage.
(Department
of Marine Biosciences, Faculty of Marine Science, Tokyo University of Marine
Science and Technology, Minato, Tokyo 108-8477, Japan, e-mail of T.
Takeuchi: take@s.kaiyodai.ac.jp)