Effects of the Methanol Extracts from the Brown Alga Dictyopteris divaricata on Feeding by the Sea Urchin Strongylocentrotus nudus and the Abalone Haliotis discus hannai.

Effects of the methanol extracts of the brown alga Dictyopteris divaricata on feeding by the sea urchin Strongylocentrotus nudus and the abalone Haliotis discus hannai were examined by the cellulose plate method. The neutral fraction of the algal extract was responsible for the deterred feeding by the sea urchin and the abalone. Chromazonarol, a sesquiterpene-substituted hydroquinone isolated from the neutral fraction, showed the most strong feeding-deterrent activity against the sea urchin and the abalone.