Effect of Artemia
feeding schedule and density on the survival and development of larval mud
crab Scylla serrata
M. Suprayudi, T. Takeuchi, K. Hamasaki,
J. Hirokawa-2002
Fisheries
Science, 68(6):
1295-1303
Abstract:
Two experiments were conducted to
determine a suitable feeding schedule and the optimal density of Artemia
nauplii on the survival and development of mud crab Scylla serrata
larvae. The first experiment consisted of 10 treatments, where rotifers were
shifted to Artemia nauplii at the zoea (Z) 1, 2, 3, 4 and 5 stages.
Five other treatments were similar to these first five; however, rotifers
were continuously added together with Artemia nauplii. The second
experiment consisted of five treatments that were carried out to determine
the optimal Artemia nauplii density. Four treatments fed different Artemia
densities (0.5, 1, 1.5, 4 individuals (ind.)/mL) and in the fifth
treatment the density of Artemia nauplii was increased with the
developing zoeal stage. The survival rate until the Z5 stage was higher when
Artemia were supplied from the Z3 stage (P < 0.05).
Mortality caused by cannibalism was observed either when Artemia
feeding was delayed or when fed at a low density (0.5 ind./mL). In contrast,
feeding Artemia from the early zoeal stage or at a high prey density
(4 ind./mL) accelerated metamorphosis and caused the acceleration of
morphological characteristics, such as a greater chela length, carapace
length and setae bearing pleopods at the Z5 stage. The chela length at the
Z5 stage decreased proportionally with the delay of Artemia feeding
or a decreasing prey density. The chela to carapace length ratio (ChL/CL
ratio,%) could be used as an indicator to predict the success of survival to
megalops. A ChL/CL ratio over 45% produced a high percentage of megalopal
molting failure. Therefore, to avoid cannibalism or excessive feeding in the
larval mud crab, Artemia should be given from the Z3 stage at an
optimal level of 1.5 ind./mL or increasing density according to the
zoeal stage.
(Department of Aquatic Biosciences, Faculty of
Fisheries, Tokyo University of Fisheries, Minato, Tokyo 108-8477, Japan,
e-mail of T. Takeuchi: take@tokyo-u-fish.ac.jp)