Biogeographic comparisons of chemical and structural defenses of the Pacific gorgonians Annella mollis and A. reticulata

Abstract

Compared to other areas of chemical ecology, biogeographic comparisons of the chemical defenses associated with benthic marine organisms are few. This study addresses geographic differences in the chemical and structural defenses of 2 Pacific gorgonians (Annella mollis and A. reticulata), found at 2 islands: Guam, Micronesia, and Lizard Island, Australia. Crude extracts and sclerites extracted from the mid-axis and tips of colonies were assayed against natural assemblages of reef fishes at Western Shoals, Guam, and Mermaid's Cove, Lizard Island. Reciprocal feeding assays clearly demonstrated that crude extracts from Annella spp. were unpalatable to natural assemblages of reef fishes at Western Shoals and Mermaid's Cove and sclerites have little or no role as generalist predator defenses. Sclerites from the tips of A. reticulata were only effective as feeding deterrents at high concentrations. Variation in the palatability of the mid-axis extracts of A. mollis suggested that chemical defenses are more concentrated at the tips of the colonies from Guam and Lizard Island. When assayed at concentrations similar to and higher than the tips the mid-axis extracts did not deter fish feeding at Mermaid's Cove.

Spatial and temporal variation of natural toxicity in cnidarians, bryozoans and tunicates in Mediterranean caves

“…Previous studies have addressed toxicity variations in cnidarians. The secondary metabolites of some species can vary quantitatively and qualitatively, depending on the biogeographic zone (Harvell et al, 1993), while other species have similar compositions of these metabolites in different habitats (Puglisi et al, 2000). The toxic behaviour of some cnidarians in this study is comparable to that of other cnidarian species.…”

Chemical mediation of interactions among marine organisms

“…was ineffective as a feeding deterrent. 268 ' 270 In addition, only the crude extracts from the tips of Rumphella sp. and Astrogorgia sp.…”

Chemical Mediation of Interactions Among Marine Organisms

“…268 Reciprocal feeding assays conducted in the laboratory and the field at both islands with crude extracts from different parts of colonies demonstrated that the production of chemical defenses of all three species are conserved among populations at these two islands. 268 In another recent study, Dube et a/. 303 The question concerning the origin of metabolites has also been recently addressed for the soft coral Lobophytum compactum..* 04 In this study, the authors inoculated freshly metamorphosed polyps of identical genetic background with different strains of zooxanthellae.…”

“…was ineffective as a feeding deterrent. 268 ' 270 In addition, only the crude extracts from the tips of Rumphella sp. and Astrogorgia sp.…”