Predator deterrence and 2,4-dibromophenol conservation by the enteropneusts Saccoglossus bromophenolosus and Protoglossus graveolens

Abstract

Saccoglossus Dromophenolosc~s I n g et al., 1994 and Protoglossus graveolens Giray & Klng, 1996 contain high concentratlons of 2,4-dibromophenol (DBP), the functlon of whlch is uncertain. Mature enteropneusts that were collected from the field and maintamed in v~tro without bromide retained DBP, which is inconsistent wlth actlve DBP secretion into the burrow env~ronment. DBP was also conserved during field manipulations that decreased food availability in situ. Further, DBP did not deter predation in feeding experiments 1~1th the anomuran crab Pagurus longicarpus and the polychaetes Glycera dibranchiata, Nereis virens and Nephtysincisa. The hermit crabs fed on S. brornophenolosus readily, and in preference to shrimp, in the field and in laboratory aquaria. Elevated DBP levels were measured in crabs that had recently consumed S. bromophenolosus, and ingested DBP was degraded to 4-bromophenol. Elevated levels of DBP in polychaetes were associated with the disappearance of enteropneusts during in vitro feeding experiments. Control incubations with DBP-containing agar plugs indicated that the polychaetes did not accumulate DBP passively. These results suggest that DBP is not an effective anti-predatory agent against hermit crabs or some predatory polychaetes. A definitive role for DBP in enteropneusts remains to be shown.

Do brominated natural products defend marine worms from consumers? Some do, most don’t

“…Thomas (1972) observed that S. otagoensis (which produces 2,3,4-tribromopyrrole) was unpalatable to fishes, while Giray and King (1997a) found that S. bromophenolosus (which produces 2,4-dibromophenol) was palatable to invertebrate consumers. In our assays, 2,4-dibromophenol did deter feeding, at 5-15ϫ the natural concentration reported for this compound (Fig.…”

“…However, when worms that produce brominated compounds have been exposed to predators, outcomes have been variable. Thomas (1972) and Prezant et al (1981) found the hemichordates Saccoglossus otagoensis and S. kowalevskii (which both produce 2,3,4-tribromopyrrole) were unpalatable to fishes, but Giray and King (1997a) found Saccoglossus bromophenolosus (which produces 2,4 dibromophenol) was palatable to two predatory polychaetes and a hermit crab. In none of the above examples were extracts or specific metabolites tested directly to assess the potential chemical basis of feeding patterns.…”

“…Direct tests of the effects of brominated compounds on microbial respiration and assimilation also produced mixed results. King (1986King ( , 1988 and Giray and King (1997b) found that these metabolites inhibited microbial respiration and assimilation, but Steward and Lovell (1997) and Lovell et al (1999) did not. Evidence that these metabolites may inhibit invertebrate settlement is more consistent.…”

“…Numerous species, particularly worms, from the Northeast Pacific (Woodin et al 1987;Woodin et al 1993), Northwest Atlantic Corresponding author (mark.hay@biology.gatech.edu). gett 1995; King et al 1995;Giray and King 1997a), West-central Atlantic (Ashworth and Cormier 1967;Woodin et al 1997;Fielman et al 1999;Cowart et al 2000), and Eastern Atlantic (Weber and Ernst 1978;Emrich et al 1990;Goerke and Weber 1990;Goerke et al 1991;Jensen et al 1992) contain these compounds. As an indication of the commonness of this phenomenon, Fielman et al (1999) investigated 40 species of infaunal invertebrates and found that 43% of the species contained halogenated metabolites.…”

Natural 14C in Saccoglossus bromophenolosus compared to 14C in surrounding sediments

“…Saccoglossus bromophenolosus were collected from the top 15 cm of sediment from Lowes Cove, Maine, USA, in July 2003. This location has been the site of numerous studies on S. bromophenolosus and their natural products (King et al 1994, Giray & King 1997. Approximately 50 worms were preserved in jars containing methanol (~30 ml); 3 whole worms were also frozen directly with liquid nitrogen.…”