The sesterterpene variabilin as a fish-predation deterrent in the western Atlantic sponge Ircinia strobilina

Abstract

The furanosesterterpene variabilin was identified in an unpalatable crude extract and proved to be a feeding deterrent when offered at 0.23% of artificial diet dry weight to reef fishes in field assays. The icthyodeterrent property of variabilin was expressed when food pellets for the palatability assays were made with calcium alginate, but not carrageenan. Variabilin probably failed to show deterrent activity in the carageenan matrix because of decomposition during the necessary heat treatment.