Trophic transfer of pyrene metabolites and nonextractable fraction from Oligochaete (Lumbriculus variegatus) to juvenile brown trout (Salmo trutta)

The trophic transfer of pyrene metabolites was evaluated by a 2-month exposure of the freshwater annelid Lumbriculus variegatus (Oligochaeta) to pyrene, followed by feeding to juvenile brown trout (Salmo trutta).The results obtained by scintillation counting (SC) proved that the pyrene metabolites produced by L. variegatus were transferred to juvenile S. trutta through diet. More detailed analyses by LC–FLD (liquid chromatography with fluorescence detection) showed that an unknown pyrene metabolite originating from L. variegatus was present in fish liver. This metabolite, although yet not properly identified, may be the glucose conjugate of 1-hydroxy-pyrene. This metabolite was not present in chromatograms of fish that were fed pyrene-spiked food pellets.In addition, the strongly bound tissue residue of L. variegatus, which was nonextractable neither by organic solvents nor by the proteolytic enzyme Proteinase K, was most likely not available for the fish through diet.Altogether, the present study shows that the metabolites of pyrene produced at low levels of the food chain may be potentially available for upper levels through diet, raising a concern about their potential toxicity to predators and supporting their inclusion in the risk assessment of PAHs.

► Transfer of pyrene metabolites was evaluated from invertebrate to fish through diet.
► Metabolites produced by Lumbriculus variegatus are taken up by Salmo trutta.
► A residual bound fraction was found and quantified in L. variegatus.
► This residual bound fraction was not available to S. trutta.