Inhibitory effects of the settlement and the metamorphosis of the abalone Haliotis discus hannai veligers by the methanol extracts from the brown alga Dilophus okamurai.

Effects of the methanol extracts of the brown alga Dilophus okamurai on the settlement and the metamorphosis of the abalone Haliotis discus hannai veligers were examined. Lethal effect as well as inducing abnormalities of behavior and metamorphosis were detected in the neutral fraction of the algal extract. Two spatane-type diterpene alcohols, as inhibitors for settlement and metamorphosis of the abalone veligers, were isolated from the neutral fraction.