| King scallop Pecten maximus L. larvae reared in stagnant sea water generally show a delayed metamorphosis. These larvae do not seem to look for a specific fixation substrate, but introduced Delesseria sanguinea Lamouroux aqueous extracts bring about a significant rise in the metamorphosis rates and the mortalities according to the concentration of extracts in the water. A series of experiments enabled the identification of the inducing agent of Delesseria sanguinea extracts: jacaranone. This product, obtained through synthesis, shows a similar activity. The optimal concentration is 0.5 mg.l-1 (3.10- 6M); for higher concentrations, the monitored drop in the metamorphosis rate is caused by an increase in the mortality rate... |
