Eiders (Somateria mollissima) obtain nodularin, a cyanobacterial hepatotoxin, in Baltic Sea food web

Nodularin (NODLN) is a cyclic pentapeptide hepatotoxin produced by the cyanobacterium Nodularia spumigena, which occurs regularly in the Baltic Sea during the summer season. Nodularia blooms have caused several animal kills in the Baltic Sea area, and NODLN has been found in mussels and fish caught from the northern Baltic Sea in 1996 to 2002. We analyzed liver samples of common eider (Somateria mollissima) for NODLN by enzyme-linked immunosorbent assay (ELISA) and liquid chromatography/mass spectrometry (LC-MS). Eiders feed extensively on mussel and can be exposed to NODLN by contaminated mussels. Fifteen eiders were shot and collected from three different sites in the western Gulf of Finland (northern Baltic Sea) in August and September 2002. Analyses by ELISA and LC-MS showed that eider liver samples contained 3 to 180 μg NODLN/kg dry weight and 0.1 to 5.8 μg NODLN/liver (dry wt). This is the first documentation of NODLN in seabirds and additional evidence for the transfer of NODLN in different parts of the Baltic Sea food web.