TOXINS FROM CYANOBACTERIA AND THEIR POTENTIAL IMPACT ON WATER-QUALITYOF LAKE KINNERET, ISRAEL

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