Induced metamorphosis in larvae of the veined rapa whelk Rapana venosa using chemical cues

Abstract

The larval metamorphosis of the veined rapa whelk Rapana venosa was investigated by exposing competent larvae to the following seven chemical cues at different concentrations and exposure time: EPI (epinephrine), serotonin, L-DOPA (L-3, 4-dihydroxyphenylalanine), GABA (γ-aminobutyric acid), acetylcholine chloride, KCl (potassium chloride), CaCl₂ (calcium chloride). Larvae of R. venosa which lost their velum after the veliger stage, crawled on their foot and produced an adult shell were considered to have metamorphosed. Compared with the control treatments, there were significantly higher percentages of larval metamorphosis in the following groups: EPI (10⁻³ M) at 6 h, L-DOPA (10⁻³ M, 10⁻⁴ M) at 6 h, L-DOPA (10⁻⁵ M) at 24 h, GABA (10⁻⁵ M) at 24 h, acetylcholine chloride (10⁻⁴ M) at 6 h, acetylcholine chloride (10⁻⁴ M, 10⁻⁶ M, 10⁻⁷ M) at 24 h and 5 mM CaCl₂ at 24 h. Acetylcholine chloride and CaCl₂ were confirmed as active inducers of R. venosa larval metamorphosis with low toxicity. In contrast, EPI, L-DOPA and GABA were less active inducers, showing high mortality rates. Serotonin and KCl had no inductive effects on larval metamorphosis. In conclusion, acetylcholine chloride and CaCl₂ are more suitable among the seven chemical cues to be applied to the artificial seeding of R. venosa.

Key words:

• Chemical cues
• inducer
• metamorphosis
• Rapana venosa

Disclosure statement

No potential conflict of interest was reported by the authors.

Editorial responsibility: Eric Thompson

Additional information

Funding

The study was supported by grants from the Scientific and Technical Supporting Program (grant number 2011BAD13B01), National Natural Science Foundation of China (grant number 31201998), and Qingdao Science and Technology Program (grant number 13-1-4-178-jch).