Chemical defense of Pterogorgia anceps, a Caribbean gorgonion coral

Abstract

Field and laboratory experiments confirmed the feeding-deterrent properties of lipidsoluble extracts of the Caribbean gorgonian octocoral Pterogorgia anceps (Pallas) with subsequent determination of the secondary metabolite responsible for this effect. A dichloron~ethane/methanol extract of P. anceps incorporated into carrageenan food strips at the same volumetric concentration as the extract occurred in gorgonian tissues deterred feeding of a natural assemblage of fishes on the same reef from which the gorgonian was collected. Bioassay-directed fractionation of this extract revealed that the deterrent property was restricted to an ancepsenolide-containing fraction; there was no effect of the less polar hydrocarbon fraction or the more polar pigmented fraction. Field assays of the ancepsenolide-containing fraction at the same volumetric concentration as it occurred in gorgonian tissues confirmed that it deterred predation by reef fishes. Laboratory assays of purified metabolites isolated from the ancepsenolide-containing fraction revealed that the feeding-inhibitory effect was restricted to a diacetoxy derivative of ancepsenolide; neither ancepsenolide nor its monoacetoxy derivative were deterrent when assayed alone or in combination. This represents the first evidence of feeding-deterrence by gorgonian metabolites of the unusual acetogenin class.

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

“…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.…”

Compounds from Deep-Sea Bubblegum Corals, Paragorgia arborea, Elicit Anti-Predation Behavior in Fish

“…Feeding assays were based on protocols used by Pawlik and Fenical [26], Pawlik et al [25], Puglisi et al [30], Lopanik et al [23], Epifanio et al [31], and Ritson-Williams and Paul [19]. First, groups of 10 or more pinfish were acclimated in tanks, during which time they were fed control food pellets that resembled treatment food but lacked chemical extracts, and mysis shrimp (Mysidae) ad libidum once per day.…”

“…Chemical compounds were extracted from DSC tissue following various procedures described by Pawlik and Fenical [26], Pawlik et al [25], Puglisi et al [30], Lopanik et al [23], Epifanio et al [31], and Ritson-Williams and Paul [19]. Prior to extractions, the volume of each coral specimen was determined by water displacement.…”

“…Additionally, generalist fishes, unlike specialist predators, would be unlikely to have evolved ways to circumvent chemical defenses [25]. Pinfish are hardy, have a broad diet range [26][27][28], are more readily available, are easy to handle and transport, and will readily consume most foods [29]. Pinfish were collected with seine, cast net, and bait traps at high salinity sites near our laboratory.…”