The Effect of Chemical Cues on Larval Settlement of the Abalone, Haliotis diversicolor supertexta

The abalone, Haliotis diversicolor supertexta, is an important aquaculture species in South China Sea. Inducing more rapid or greater degree of settlement of H. diversicolor supertexta larvae using chemical cues can significantly improve the commercial hatchery production of this valuable species. In this study, the effects of 11 chemicals on inducing larval settlement of the H. diversicolor supertexta were investigated in the laboratory. Among the chemicals tested, K+ (10 and 20 mM), Ca2+ (1 mM), NH4+ (0.1 mM), gamma-aminobutyric acid (at 10-7 to 10-2 M), 3-isobutyl-1-methylxanthine (10-4 M), 3-(3,4-dihydroxyphenyl)-l-alanine (at 10-6 to 10-5 M), and dopamine (10-6 M) induced high percentages of the larvae to settle, while Mg2+, choline, acetylcholine, and serotonin showed no obvious induction on larval settlement. Larval settlement was significantly induced after exposure to 20 mM KCl for only 2 h. KCl was not only an effective inducer, but also an inexpensive and easily available chemical, therefore it maybe a potentially economical inducer in the commercial production.