Additional file 1: Figure S1. PFAS profiles in quagga mussel (Dreissena bugensis; N = 143), Asiatic clam (Corbicula fluminea; N = 30) and blue mussel (Mytilus edulis; N = 5). PFHpA, PFHxS and PFDS were excluded as their concentrations were < LOQ in all the samples. Figure S2. Standard Ellipse Areas (SEA, %o2) of the Bayesian ellipses for each species; perch (Perca fluviatilis, N = 24), eel (Anguilla anguilla, N = 31), quagga mussel (Dreissena bugensis, N = 30) and Asian clam (Corbicula fluminea, N = 5). The red crosses represent the corrected median SEA (SEAc). Table S1. Condition Index, stable isotope data (δ13C and δ15 N), and PFAS concentrations (mean and range (between brackets); ng/g ww) of the mussels (quagga mussel (Dreissena bugensis), Asian clam (Corbicula fluminea) and blue mussel (Mytilus edulis) at each location. Table S2. MRM transitions (precursor and product ions), internal standards (ISTDs), cone voltages (V) and collision energy (eV) for the target perfluoroalkyl substances and their internal standards. Table S3. Mean and range trophic levels (TLs) of the organisms. Table S4. PFAS concentrations (ng/g ww) and stable isotope data (δ13C and δ15N) in fish muscle tissue (eel (Anguilla anguilla) and perch (Perca fluviatilis)) at each location. Table S5. Overlap in the corrected Standard Ellipse Area (SEAc; %o2) of the ellipses of quagga mussel (Dreissena bugensis, N = 30), Asian clam (Corbicula fluminea, N = 5), perch (Perca fluviatilis, N = 43) and eel (Anguilla anguilla, N = 56). Table S6. Slopes and trophic magnification factors (TMFs) for the target analytes that were significantly related with trophic level (TLs) of the organisms. Table S7. Summary of results of PFCs in the environmental study samples (fish, results in ng/g ww) of the interlaboratory study of the reference material [72] and reference concentrations (average values) measured in the present study.