Cattle mortality attributed to the toxic cyanobacterium Cylindrospermopsisraciborskii in an outback region of north Queensland

Three cows and ten calves were found dead near a farm dam on a cattle prope rty at McKinlay in northwest Queensland, Australia. At that time, the dam c ontained an algal bloom which was identified as a monoculture of the cyanob acterium C. raciborskii. Histological examination of the liver of a calf ca rcass showed signs consistent with poisoning caused by hepatotoxin. The hep atotoxic alkaloid cylindrospermopsin was detected in material harvested fro m the dam (4.1 x 10(-15) g cell(-1)) and in a pure culture of an isolate fr om the bloom (4.4 x 10(-15) g cell(-1)). An extract of this material was le thal to mice after 24 h at an intraperitoneal concentration of 153 mg kg(-1 ). This appears to be the first report of animal poisonings attributed to t he cyanobacterium C. raciborskii. (C) 1999 by John Wiley & Sons, Inc.