Hydroxylated and methoxylated polybrominated diphenyl ethers in long-tailed ducks (Clangula hyemalis) and their main food, Baltic blue mussels (Mytilus trossulus × Mytilus edulis)

Long-tailed ducks (Clangula hyemalis) that breed in northern Europe and western Siberia and commonly winter in the Baltic Sea, are threatened by a significant population decrease. The ducks are, by primarily feeding on Baltic blue mussels (Mytilus trossulus × Mytilus edulis) while wintering in the Baltic Sea, potentially subjected to high levels of toxic hydroxylated polybrominated diphenyl ethers (OH-PBDEs). To assess long-tailed ducks exposure to polybrominated phenols (PBPs), polybrominated anisoles (PBAs), hydroxylated polybrominated diphenyl ethers (OH-PBDEs), their methylated counterparts (MeO-PBDEs) and polybrominated diphenyl ethers (PBDEs), livers of ten long-tailed ducks wintering in the Baltic Sea were analysed. Pattern and levels of analytes in long-tailed ducks (liver) and blue mussels sampled in March and May at nine sites in the Baltic Sea were compared. The geometric mean concentration (ng/g l.w.) in livers of long-tailed ducks and Baltic blue mussels were: Σ2PBPs: 0.57 and 48; Σ2PBAs: 0.83 and 11; Σ7OH-PBDEs: 6.1 and 45; Σ7MeO-PBDEs: 3.8 and 69; Σ7PBDEs: 8.0 and 7.2, respectively. Based on an estimated daily intake of 450 g fresh blue mussel meat, long-tailed ducks daily dietary intake of brominated substances while foraging in the Baltic Sea in March–May was estimated to; 390 ng Σ2PBPs, 90 ng Σ2PBAs, 370 ng Σ7OH-PBDEs, 590 ng Σ7MeO-PBDEs and 59 ng Σ7PBDEs. The low levels of PBPs, PBAs, OH-PBDEs and MeO-PBDEs in the long-tailed duck livers compared to blue mussel, despite a continuous daily intake, suggest that these compounds are poorly retained in long-tailed ducks. [Display omitted] •OH-PBDEs, MeO-PBDEs and PBDEs in blue mussel and long-tailed duck were measured.•OH- and MeO-PBDE levels were higher in birds sampled the Baltic than in the Arctic.•OH- and MeO-PBDE levels were higher in mussels in the Baltic Sea than in the Arctic.•Levels of OH-PBDEs in Baltic blue mussels were significantly higher in summer.•The PBDE profile in benthic feeding sea ducks differs from other marine birds.