The barnacle Savignium milleporum is an obligatory symbiotic epizoan of the reef-building hydrozoan Millepora dichotoma, inhabiting virtually every M. dichotoma colony in Eilat, in which it carries out complex trophic interactions with its host. In the present study, barnacle-removal experiments were conducted on hydrozoan colonies in the laboratory and in the field, and subsequent algal cover was observed. The results show that de-barnacled colonies experience a dramatic increase in fouling by various algae and fungi. It is suggested that barnacles provide the host with a defense against fouling organisms through feeding on spores, capsules, and larvae of potential settlers.
- Coral reefs