The occurrence of cyanobacterial toxins in new York lakes: Lessons from the MERHAB-Lower great lakes

New York State is bordered by Lake Erie, Lake Ontario and Lake Champlain, which provide recreational opportunities and drinking water for over 20 million people. Little is known about the occurrence of toxic cyanobacteria in New York waters. In 1999 and 2000, several dogs died from anatoxin-a poisoning after contact with Lake Champlain algae. In response to these events, an intensive field program was initiated to develop and evaluate monitoring methods for detection of cyanobacterial toxins in freshwater systems. This work resulted in the development of a tier-based system for monitoring harmful algal blooms. Between 2000 and 2004, more than 2,000 samples were collected and analyzed for the occurrence of cyanobacterial toxins from sites across New York State. These samples were tested for the hepatotoxic microcystins and cylindrospermopsin as well as the neurotoxins, anatoxin-a, and paralytic shellfish poisons (PSP). A simple extraction procedure using 50% methanol gave > 90% recovery of PSP toxins, microcystins, and anatoxin-a from a single sample. This extract was analyzed for cyanobacteria toxins using multiple techniques including ELISA, enzyme inhibition assays, and HPLC with fluorescence, photodiode array, or mass spectrometry detectors. Microcystins were found at > 1 mu g L-1 in 15% of the samples. Anatoxin-a was found less frequently but was often associated with animal fatalities. The PSP toxins and cylindrospermopsin were found only in rare instances. In some lakes (i.e., Oneida Lake), > 50% of the samples tested positive for microcystins. These results suggest that cyanobacterial toxins may be a common event in eutrophic waters, and their occurrence should be a concern for lake managers and public health officials.