There has recently been a world wide increase in the occurrence of toxins produced by microorganisms in lakes, oceans and estuaries. The causes for outbreaks of such biotoxins are poorly understood. The Biotoxins Laboratory is devoted to better understanding the role of biotoxins in aquatic systems and their importance as a threat to public health and water quality. Researchers in this laboratory have pioneered studies of coastal red tide toxins and occurrence of liver and nerve toxins in New Hampshire lakes. Multidisciplinary research includes biochemical, physiological, genetic and ecological studies of biotoxins. One goal of the Biotoxins Laboratory is to develop sensitive biotoxin assay methods that can be used by lake monitors of the LLMP as well as by suppliers of drinking water.