Polyphenols in brown algaeFucus vesiculosus andAscophyllum nodosum: Chemical defenses against the marine herbivorous snail,Littorina littorea

ABSTRACT-Wounding of both terrestrial and marine plants is known to induce chemical responses in the plants; the induced compounds may defend against herbivory or act in wound-healing processes. We demonstrate here, for the first time, induction of phlorotannins in kelps (Phaeophyta, Laminariales). an important and widespread group of marine benthic algae. The rapid response of kelps to mechanical wounding contrasts with previously published work on other marine algae, where response has been slower. In 4 of the 5 species tested, induction (increases of approximately 30 to 9036 of original levels) occurred very rapidly, within 1 to 3 d of wounding, although the magnitude and duration of the induction varied among species and tissue types. Many induced responses persisted for 5 to 7 d and then relaxed. Relaxation times are a critical component in the hypothesized cost-effectiveness of induced versus constitutive defenses, and this is one of the first attempts to measure relaxation times of chemlcal defenses in marine algae. The temporal persistence of the response suggests an antiherb~vory rather than a wound-healing function for induction of phlorotannins, although this needs further testing KEY MiORDS Kelp phlorotannins . Induction Relaxat~on Chemlcal defense . Wound heal~ng Herb~vory

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rapid phlorotannin induction and relaxation in five Washington kelps

Hammerstrom¹,

Dethier²,

Duggins³

1998

“…Although phlorotannins are often considered to function as chemical defenses against herbivores, both direct tests (Steinberg 1988, Steinberg & van Altena 1992, Boettcher & Targett 1993, Steinberg et al 1995, Pavia & Toth 2000, Deal et al 2003 and correlative experiments (Van Alstyne 1988, Denton & Chapman 1991, Steinberg et al 1991, Tugwell & Branch 1992, Yates & Peckol 1993, Targett et al 1995, Pavia et al 1997) have shown great variance in the deterrent effects of phlorotannins of brown algae against marine herbivores; e.g. (1) high-molecular weight phlorotannin mixtures (>10 kDa) may affect herbivore physiology while low-molecular weight phlorotannins from the same alga may not (Geiselman & McConnell 1981, Boettcher & Targett 1993; (2) some herbivores with acidic guts avoid phlorotannin-rich seaweeds while other herbivores with basic or surfactant-rich digestive tracts readily consume the same seaweeds (Tugwell & Branch 1992, Targett et al 1995, Targett & Arnold 1998; (3) effects on herbivores can vary geographically even among herbivores with similar digestive systems: herbivores in temperate Australasia are minimally affected by phlorotannin-rich extracts that deter similar herbivores from the Pacific coast of North America (Steinberg & van Altena 1992, Steinberg et al 1995.…”

Section: Introductionmentioning

confidence: 99%

Ambiguous role of phlorotannins as chemical defenses in the brown alga Fucus vesiculosus

Kubanek

Lester²,

Fenical³

et al. 2004

Brown seaweeds (Fucales) produce phlorotannins that are often considered chemical defenses against herbivores. The many correlative and fewer direct tests conducted have shown effects of phlorotannins on herbivore feeding behavior to be variable. In an attempt to clarify the roles of phlorotannins versus other metabolites in defending brown algae, we conducted bioassay-guided fractionation of herbivore-deterrent extracts from the commonly studied brown alga Fucus vesiculosus. Feeding by the amphipods Ampithoe valida and A. longimana and the sea urchin Arbacia punctulata was suppressed by crude and water-soluble extracts of F. vesiculosus, but this deterrence was lost following storage or fractionation of the active, water-soluble extract. Phlorotannins in these extracts did not decompose in parallel with the loss of feeding deterrence. F. vesiculosus phlorotannins were fed to herbivores at 3 to 12 × the isolated yield (or 4.2 to 16.8% of plant dry mass). No herbivore was deterred from feeding by concentrations of 3 or 6 ×, but A. valida (the only test herbivore that readily consumes F. vesiculosus in the field) was deterred at 12 × isolated yield. When juvenile A. valida were raised on an artificial diet containing F. vesiculosus phlorotannins at 3 × isolated yield, the phlorotannin-rich diet significantly enhanced, rather than reduced, amphipod survivorship and growth relative to an equivalent diet without phlorotannins. Females ovulated only on the phlorotannin-rich diet. Compounds other than phlorotannins appear to defend the F. vesiculosus populations we investigated, but we were unable to identify these unstable compounds.

“…Compounds from marine algae have been hypothesized to play important defensive roles in marine algae (Ogden & Lobe1 1978, Norris & Fenical 1982, Hay 1984b), but expenmental bioassays with these secondary metabolites have rarely been conducted (Geiselman & McConnell 1981, McConnell et al 1982, Paul & Fenical 1983, Steinberg 1984.…”

Section: Introductionmentioning

confidence: 99%

Chemical defense in tropical green algae, order Caulerpales

Paul¹,

Fenical²

1986

181

119

Forty marine algae of the order Caulerpales were chemically investigated. Virtually all produce toxic secondary metabolites of a unique and unprecedented class. These metabolites are generally Linear terpenoids, but unusual structural features such as aldehydes and bis-enol acetate functional groups make these compounds uruque. The conlpounds are t o n c or deterrent toward microorganisms, sea urchin larvae, and herbivous fishes, and when incorporated into diets at naturally occurring concentrations cause mortality in juvenile conch. Concentrations of bioactive metabolites were found to show httle variation in different plant parts such as blades, shpes and holdfasts. Young growlng tips and reproductive structures contained higher concentrahons than mature plant tissues on a dry weight and ash-free dry weight basis. Chemical variation, both qualitahve and quantitative, was observed in different populations of the same species. In the cases examined, algae growing in areas known to have the highest herbivory produced the greatest concentrations and varieties of secondary metabolites. Based upon these observations and pnor feeding preference data, we conclude that chemical defense IS a major factor In the sumval of marine algae within this order.