Effects
of temperature on the egg incubation period, survival and developmental
period of larvae of the mud crab Scylla serrata (Forskĺl) (Brachyura:
Portunidae) reared in the laboratory
Katsuyuki
Hamasaki-2003
Aquaculture, 219(4): 561-572
Abstract:
This
study examined effects of temperature on the egg incubation period, survival
and developmental period of larvae of the mud crab Scylla serrata
reared in the laboratory. Pre-mated females were held in tanks in which
temperature varied seasonally; their spawning and hatching were recorded
daily. The number of days from spawning to hatching and mean rearing
temperature were determined for 92 females. The egg incubation period
decreased exponentially from 30 to 10 days with increasing mean temperature
in the range 20.3–30.0 °C. Larvae were reared in 1-l beakers at seven
temperatures (17, 20, 23, 26, 29, 32 and 35 °C) and fed with rotifers and Artemia
nauplii. Survival to the first crab stage occurred when larvae were reared
at 23–32 °C: the best survival rate was obtained at 29 °C. Also, the
number of days from hatching to attainment of each larval stage decreased
with increasing temperature. Relationships between mean temperature (T)
and egg incubation period and larval developmental period from hatching to
reach the megalopal stage (D) were analyzed using the following three
equation models: power function, D=aTb; Bělehrádek's
equation, D=a(T-a)b;
and from heat summation theory, D=a/(T-a).
For both egg and larval development, the equation of heat summation theory
was the best model to characterize the relationship between temperature and
the number of days required for development. The biological lower critical
temperature represented by parameter a
was
similar for eggs and larvae: 13.93 and 13.82 °C, respectively, for Bělehrádek's
equation and 15.70 and 15.08 °C for heat summation theory.
(Yaeyama
Station, Japan Sea-Farming Association, Ishigaki, Okinawa 907-0451, Japan,
e-mail: katsuyuki-hamasaki@jasfa.or.jp)