Widespread occurrence of natural halogenated organics among temperate marine infauna

Abstract

Despite the global prevalence of marine sedimentary habitats, the potential for chemically mediated ecological interactions within these assemblages remains poorly known. Using GC/MS, we examined methanol extracts of worm, mollusc, and crustacean macroinfauna from 2 local intertidal sandflat communities for volatile organohalogens, a common, often bioactive class of secondary metabolites from marine organisms. Halogenated compounds were newly identified from 11 common polychaete species in the families Capitellidae, Chaetopteridae, Cirratulidae, Glyceridae, Pectinariidae and Spionidae. Tentative structures of these halometabolites are proposed based on GC/MS data. The represented chemical classes included aromatic mono- and dibrominated hydroxyphenylpropanoids, nitrogen-containing bromoalkylpyrroles, as well as brominated and chlorinated hydrocarbons and sulfides. Among the molluscs, only Terebra dislocata (Prosobranchia) contained an organohalogen compound (2,6-dibromophenol), which is likely derived from its diet of hemichordate worms. Volatile haloorganics were not found in amphipod and nemertean taxa. Possession of these compounds was not a function of any particular phylum, size categorization, or trophic mode, although hemichordates and all Capitellid and Spionid polychaetes collected at these sites invariably contained halocompounds. Most (40 of ca 54 taxa) of the numerically dominant macroinfaunal taxa at these 2 sites were examined in this survey; of these, 43% contained halometabolites, including the broadly distributed species Mediomastus ambiseta, Heteromastus filiformis, Streblospio benedicti, Tharyx marioni, and Saccoglossus kowalevskii, Thus, the potential for widespread occurrence of halogenated compounds among infauna is great. The presence of organohalogens in many common and abundant polychaete species suggests a general hiological significance for these metabolites, a result of potential interest to marine ecologists, toxicologists and environmental chemists.