Toxins from cyanobacteria and their potential impact on water quality of Lake Kinneret, Israel

A number of different species of cyanobacteria (blue-green algae) produce toxins of several different types. Cyanobacterial blooms present a serious health concern when they occur in water bodies that supply potable water. Lake Kinneret, the major water source in Israel, was characterized for many years by relatively stable phytoplankton populations which fluctuated with the seasons in a quite predictable manner. An exceptional bloom of the filamentous cyanobacterium Aphanizomenon ovalisporum, which produces hepatotoxin, was observed for the first time in Lake Kinneret during the fall of 1994. Cylindrospermopsin, a toxin produced by A. ovalisporum, was purified and chemically characterized. The potential implications of cylindrospermopsin-producing A. ovalisporum bloom in Lake Kinneret on water quality is discussed, together with a general description of cyanobacterial toxins and their occurrence in natural waters.