DIETARY ABSORPTION OF SEDIMENT-BOUND FLUORANTHENE BY A DEPOSIT-FEEDING GASTROPOD USING THE C-14 CR-51 DUAL-LABELING METHOD

Polycyclic aromatic hydrocarbons (PAH) constitute a broad class of tox ic, environmentally persistent, particle-reactive organic compounds th at are ubiquitous in aquatic and terrestrial ecosystems This study was designed to measure ingestion and dietary absorption of the PAH, fluo ranthene, by two genotypes of a deposit-feeding gastropod using the C- 14:Cr-51 dual-labeling method. Sediment processing rate, fluoranthene ingestion rate, selective ingestion of fluoranthene-containing particl es, and fluoranthene absorption rate varied as a function of snail bod y size and genotype. Absorption efficiency of sediment bound fluoranth ene did not vary as a function of body size but differed between genot ypes, averaging 42 to 46% for Clone A and 22 to 36% for Clone B. We co uld detect no significant metabolism of ingested fluoranthene to disso lved organic carbon or CO, during 24 h following its ingestion. The C- 14:Cr-51 dual-labeling method provides a powerful approach for investi gating the dietary absorption of sediment-bound contaminants by (1) al lowing the calculation of ingestion selectivity, sediment processing l ate, contaminant ingestion rate, and absorption efficiency in individu al, small invertebrates; (2) permitting estimation of the fraction of ingested-absorbed contaminant that is metabolized and released via dif ferent routes following its ingestion; and (3) facilitating evaluation of the relative importance of porewater versus ingested sediment as r outes of contaminant uptake by animals.