Accumulation of microcystin-LR in dead domestic duck at Iso harbor, Lake Biwa, Japan

Abstract

In Iso harbor, which is located in the north basin of Lake Biwa, 22 of 30 domestic duck (Anas platyrhynchos var. domestica; a crossbreed between Mallard A. platyrhynchos and domestic duck) died during August and September 2007. The deaths were not the result of botulism because there were no signs of acute toxicity. Microcystin (MC)-RR and Microcystin-LR were detected in water samples from the harbor. Liver tissues from the dead duck contained 560 ng g^-1 DW (178 ng g^-1 FW) of MC-LR. MC-LR is a high toxic cyanotoxin produced by cyanobateria, and the duck liver tissue contents were high compared with previous studies. Therefore, we suggest the duck died from MC-LR levels having been exposed to toxic cyanobacteria. This is the first case in which cyanotoxin has been identified in dead waterfowl in Japan.