HARMFUL CYANOBACTERIA From mass mortalities to management measures

Abstract

When the first triennial international conferences on photosynthetic prokaryotes, including cyanobacteria, began in the 1970’s, their packed and novel proceedings included no contributions on the toxicology or health hazards of cyanobacteria. In 2004, the “Sixth International Conference on Toxic Cyanobacteria” in Bergen (another triennial series) is expected to attract several hundred participants, all working with, or concerned in other ways, with cyanobacterial toxins, from their molecular biology, to risk management. The drivers accounting for the rapid increase in knowledge about cyanobacterial toxins in the intervening decades have included: fundamental research; the increasing availability of enabling technologies e.g. analytical techniques and molecular biology tools; a “need to know” from the health and environmental agencies, the water industry and water-users; and several human and animal poisoning incidents associated with cyanobacterial toxins to which modern methods have been applied. Cyanobacteria are equipped to flourish in aquatic environments where they can produce blooms, scums and mats (Mur, 1983; Mur et al., 1999). They also produce a diverse range of toxins (Codd et al., 1989, 1999; Namikoshi and Rinehart, 1996; Carmichael 1997, 2001; Duy et al., 2000; Sivonen and Jones, 1999; Sivonen 2000). The cyanobacterial toxins include human and animal health hazards which can present risks of illness and mortality at environmentally-encountered concentrations (Falconer, 1996, 1998; Kuiper-Goodman et al., 1999; Codd et al., 1999). This review includes early and recent examples of human and animal illnesses and deaths associated with cyanobacterial mass populations, in some cases attributable to their toxins. We briefly consider cyanobacterial toxins among the plethora of other cyanobacterial bioactive compounds and whether the main cyanobacterial hazards to human health are now identified. Steps to mitigate the