Toxic effects of cembranolides derived from octocorals on the rotifer Brachionus plicatilis Müller and the amphipod Parhyale hawaiensis (Dana)

The diterpenoids eunicin, eupalmerin acetate, and crassin acetate derived from octocorals were found to be toxic to the rotifer Brachionus plicatilis Müller and the amphipod Parhyale hawaiensis (Dana) at estimated concentrations ranging from 1 ppm to 100 ppm. Exposure of animals to a concentration ? 1 ppm resulted in either loss of swimming activity or mortality at 48 h. No ciliary loss was evident in the rotifer as had been reported in ciliated larvae of the nudibranch Phestilla sibogae Bergh.The cembranolides may serve as chemical defenses against predation and in the competition for space amongst the sessile organisms on coral reefs.