Dietary absorption of sediment‐bound fluoranthene by a deposit‐feeding gastropod using the 14C:51Cr dual‐labeling method

Abstract

AbstractPolycyclic aromatic hydrocarbons (PAH) constitute a broad class of toxic, environmentally persistent, particle‐reactive organic compounds that are ubiquitous in aquatic and terrestrial ecosystems. This study was designed to measure ingestion and dietary absorption of the PAH, fluoranthene, by two genotypes of a deposit‐feeding gastropod using the 14C:51Cr dual‐labeling method. Sediment processing rate, fluoranthene ingestion rate, selective ingestion of fluoranthene‐containing particles, and fluoranthene absorption rate varied as a function of snail body size and genotype. Absorption efficiency of sediment‐bound fluoranthene did not vary as a function of body size but differed between genotypes, averaging 42 to 46% for Clone A and 22 to 36% for Clone B. We could detect no significant metabolism of ingested fluoranthene to dissolved organic carbon or CO2 during 24 h following its ingestion. The 14C:51Cr dual‐labeling method provides a powerful approach for investigating the dietary absorption of sediment‐bound contaminants by (1) allowing the calculation of ingestion selectivity, sediment processing rate, contaminant ingestion rate, and absorption efficiency in individual, small invertebrates; (2) permitting estimation of the fraction of ingested/absorbed contaminant that is metabolized and released via different routes following its ingestion; and (3) facilitating evaluation of the relative importance of porewater versus ingested sediment as routes of contaminant uptake by animals.