17Paralytic shellfish poisoning (PSP) toxins were detected in blue mussels (Mytilus 18 edulis) from two harvesting areas, Eyjafjordur on the north coast and Breidafjordur on 19 the west coast of Iceland in 2009. During a bloom of Alexandrium spp. at both 20 locations in June of that year, blue mussels were found to be contaminated with 21 paralytic shellfish toxins (PSTs), leading to extensive closures of these harvesting 22 sites. 23Phytoplankton data taken during this time showed the presence of large numbers of A. 24 tamarense, with smaller numbers of A. ostenfeldii also being detected. Mussel 25 2 samples were analysed by mouse bioassay (MBA) and liquid chromatography with 26 fluorescence detection (LC-FLD). Toxicity over 10 times the European Union (EU) 27 regulatory limit was observed in samples from Eyjafjordur while levels over 4 times 28 this limit were detected in samples from Breidafjordur. The toxin profile determined 29 by LC-FLD was found to be composed primarily of the carbamate toxins 30 gonyautoxin-2,3 (GTX-2,3). Saxitoxin (STX) was also detected in all samples 31 analysed and was the second most abundant toxin present. Gonyautoxin-1,4 (GTX-32 1,4) was detected at lower concentrations in half the samples analysed from both 33 locations. Comparison is made between predicted toxin profiles from these algal 34 species and the toxin profiles determined through LC-FLD analysis. 35These results represent the first identification and PST profile determination in 36 shellfish harvested from Icelandic waters. 37 38