2.1. PAH-Contaminated Diet Preparation

Three aromatic fractions were used for exposures: (i) A pyrolytic fraction (PY) extracted from sediments collected in a polluted site of the Seine Estuary (Oissel, France) and (ii) two petrogenic fractions obtained from Erika fuel (heavy oil; HO) and Arabian Light crude oil (LO). PAHs extractions were performed as previously described [7]. Zebrafish TU strain (ZFIN ID: 76 ZDB-GENO-990623-3) was used and larvae were exposed from their first meal (at 5 dpf) onward using spiked food pellets [33]. Three concentrations, 0.3X, 1X and 3X were used with the 1X concentration corresponding to the 16 PAHs used as indicators by the US Environmental Protection Agency (US-EPA) at 5 μg·g⁻¹ dw food, representative of the concentrations found in mollusks in the Seine Estuary. Although it does not give an accurate representation of the fractions’ compositions, this subset of PAHs has been used for comparison with concentrations found in the environment (see in Table S1 a detailed description of actual fractions compositions). Diets are named after the origin of the fraction and its concentration: the 1X pyrolytic fraction diet will be named PY-1X. For each exposure, a fourth control treatment was included corresponding to the plain food treated as spiked-food with dichloromethane which was used as carrier solvent for PAHs spiking. Because the fraction extracted from the original sample is a mixture of PAHs, the term mixture will also be used more or less synonymously with fraction.