Some genera of cyanobacteria are capable of producing toxins that can have severe hepatic (affecting the liver) or neurological (affecting the nervous system) effects. The development of blooms, which release toxins into the water, make them a potential health hazard in water supply source and recreational waters.
This paper reports the collation and review of cyanobacteria and cyanotoxin data collected by regional councils to extract information of public health importance. The study, which reviewed data collected by eight regional councils up to 2009 (inclusive), found that sampling by these councils had identified a total of 43 different genera, 16 of which contain toxin-producing species. Detections of the toxin-producing genera Anabaena and Microcystis were reported by the greatest number of councils. The data showed that while there was a correlation between toxin and cell concentrations in Lake Forsyth, a wide range of toxin concentrations could be associated with very similar total cell concentrations. This suggests the need for caution when assessing the health risk associated with cyanotoxins based on the cell count in a water. The data also showed that the nodularin (toxin) concentration in Lake Forsyth can exceed its provisional maximum acceptable value by up to a factor of 300.