Defensive properties of secondary metabolites from the Caribbean gorgonian coral Erythropodium caribaeorum

Abstract

Field expenments support previous laboratory assays Indicating that crude lipid-soluble extracts of the Canbbean encrusting gorgonian octocoral Erythropod~um canbaeorum (Duchassalng & Mlchelotti) detel predation by reef fishes An extract of E canbaeorum incorporated into carrageenan food strips at the same volumetric concentration as i t occurred in gorgonian tlssues deterred feeding of a natural assemblage of fishes on the same reef from which the gorgonian had been collected Fleld assays using carrageenan stnps conta~ning naturally occurnng concentratlons of several pulitled secondary metabolites isolated from the crude extract revealed that the f e e d~n g deterrent effects were present In a fraction containing chlonnated dlterpenoid (Cz0) compounds (erythrolldes), but not in a fraction conta~ning sesquiterpene (Cl5) hydrocarbons (of which erythrodiene, a previously unreported manne natural product was a major component) Three compounds were purlfled from the erythrolide fraction erythrolide A, erythrolide B and erythrolide D Only the last 2 of these compounds, when assayed independently, Inhibited feeding of reef flshes at the natural concentratlons found in E canbaeorun~ Whlle the erythrolides appear to defend E canbaeorum from reef predators, the funct~on of sesqulterpene hydrocarbons, which occur in high concentratlons in the llpid-soluble extracts of many octocorals, remains unclear

A reappraisal of the chemical and physical defenses of Caribbean gorgonian corals against predatory fishes

“…Crude organic extracts from each of the 32 species tested (100%) were unpalatable to Thalassoma bifasciatum in laboratory assays, but the sclerites of only 2 species (6.3%) deterred consumption of assay food. The species of wrasse used in this study has often been considered a model generalist predator, and the results of assays with T. bifasciatum in previous studies have consistently agreed with the results of field studies in which the deterrent effects of metabolites or spicules were tested on a natural assemblage of reef fishes (Fenical & Pawlik 1991, Swearingen & Pawlik 1998, Wilson et al 1999 (Pawlik et al 1987). In that study, only 51% of the 37 surveyed gorgonian 'types' yielded crude organic extracts that were deterrent to Thalassoma bifasciatum; 11% were classified as moderately unpalatable and the remaining 38% were palatable.…”

“…Organic extracts of gorgonians do not appear to have strong antimicrobial activity against marine bacteria (Jensen et al 1996). The most common hypothesis is that secondary metabolites are anti-predatory agents, and studies have consistently demonstrated antipredatory properties of gorgonian crude extracts and purified compounds (Pawlik et al 1987, Fenical & Pawlik 1991, Pawlik & Fenical 1992, Maia et al 1999, Koh et al 2000.…”

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

“…secondary metabolites) and/or structural (i.e. sclerites) defenses against predation (Pawlik et al 1987, Harvell et al 1988, Fenical & Pawlik 1991, Pawlik & Fenical 1992, Van Alstyne & Paul 1992, West 1997, 1998. Some species exhibit intra-colony variation in secondary metabolite and sclerite concentrations suggesting that different parts of the colony rely more upon chemical defenses and others rely upon structural defenses (Harvell & Fenical 1989, Van Alstyne & Paul 1992.…”

Size structure and geographic variation in chemical resistance of sea fan corals Gorgonia ventalina to a fungal pathogen

“…Kim 1994, Slattery et al 1995, Jensen et al 1996, anti-fouling (Targett et al 1983, Standing et al 1984, Wilsanand et al 1999 anti-fungal (Kim et al 2000a,b), and/or predator (e.g. Pawlik et al 1987, Sammarco et al 1987, Harvell et al 1988, Harvell & Fenical 1989, Pawlik & Fenical 1989, Fenical & Pawlik 1991, Van Alstyne & Paul 1992, Cronin et al 1995, Slattery 1999) -and competitor (e.g. Sammarco et al 1983, Rittschoff et al 1985, La Barre et al 1986) -deterrent secondary compounds.…”