The effect of chemical cues
on settlement behaviour of blacklip pearl oyster (Pinctada margaritifera)
larvae
M.S.
Doroudi, P.C. Southgate-2002
Aquaculture,
209(1-4) : 117-124
Abstract:
Inducing more rapid or greater degree of settlement
of blacklip pearl oyster (Pinctada margaritifera) larvae using
chemical cues can significantly improve the commercial hatchery production
of this valuable species. For this purpose, epinephrine, norepinephrine and
γ-aminobutyric acid (GABA) were assessed at four concentrations (10-2,
10-3, 10-4 and 10-5 M), and in conjunction
with plastic filaments for their ability to induce settlement of P.
margaritifera larvae. In all concentrations tested, neither epinephrine
nor norepinephrine had a significant effect on settlement and crawling
behaviours of P. margaritifera larvae. Settlement of larvae occurred
after 24 h in the presence of GABA at concentrations of 10-3 and
10-4 M; however, mortality was high (32%) at a concentration of
10-3 M. Settlement and crawling behaviours were significantly
greater (P<0.05) and mortality significantly lower (P<0.05)
in the presence of plastic filaments alone than those exposed to GABA at a
concentration of 10-4 M. However, larvae in the presence of
plastic filaments and exposed to GABA showed significantly reduced (P<0.05)
swimming behaviour and significantly greater (P<0.05) crawling and
settlement behaviours than larvae in the presence of GABA alone or plastic
filaments alone. The presence of GABA increased settlement of P.
margaritifera larvae onto plastic filaments from 14% in treatments with
plastic filaments only, to 25% in the treatment with plastic filaments and
GABA. The result of this study showed that GABA has a potential to increase
the settlement rate of P. margaritifera larvae in hatcheries.
(Maxima Pearling Co. Pty. Ltd., PO Box 843, Broome,
WA 6725, Australia)