Embryonic development and larval and post-larval growth of the tropical scallop Nodipecten (= Lyropecten) nodosus (L. 1758) (Mollusca: Pectinidae)
J.P. De la Roche, B.Marín, L. Freites, A. Vélez -2002
Aquaculture
Research, 33(11): 819-828
Abstract:
This work describes for the first time the
embryonic development of the tropical scallop Nodipecten nodosus.
Larval and post-larval growth parameters and some characteristics of larvae
shell morphology were also ascertained. The larvae were obtained from the
induced spawning of a group of broodstocks under controlled laboratory
conditions. After fertilization, larval cultivation was carried out in
conical tanks at a temperature of 26-27°C. Larval density was controlled as
a function of larval growth to give 10, 5 and 3 larvae mL-1 from
days 1, 3 and 8 respectively. The larvae were nourished with a 1:1 mix of Isochrysis
galbana (clone T-ISO) and Chaetoceros gracilis in portions
varying between 30000 and 70000 cells mL-1. Expulsion of polar
groups was observed 5 and 15min after fertilization, whereas the first
cellular division occurred after 30min. The first gastrule ciliates and
trochophore larvae were noted after 8 and 18h had elapsed, respectively,
whereas prodissoconch I, or D-larvae, were discerned after 26h.
Subsequently, larvae with prodissoconch II or veliger-conch appeared at 30h.
Larval development continued for 10-12days, followed by metamorphosis, at an
approximate length of 208-230µm. The growth of the post-larvae was
evaluated for 9days. Larval and post-larval growth corresponded to the
linear equations L=71.85+10.85t, r2=0.99,
and L=44.09+17.81t, r2=0.94 respectively.
Accordingly, larval morphology and size disparities are discussed with
respect to other tropical pectinids.
(Instituto Espanol de Oceanografia, Aptdo
Postal 130, 15080 Coruna, Spain. E-mail: jproche@hotmail.com)