Paralytic shellfish toxin producing blooms of Anabaena circinalis are a frequent occurrence in freshwaters throughout Australia, spanning tropical to cool temperate regions. These blooms pose serious management and health issues, with blooms sometimes extending for over 1000 km and with stock deaths associated with blooms. We are investigating the role of akinetes in the bloom dynamics of A. circinalis . Akinetes are presumed to be a resistant resting stage due to their capacity to survive environmental conditions which are deleterious to vegetative cells and because of their ability to form germling cells. We are using cultured strains isolated from blooms representing the diversity of biogeographic regions in Australia. We found some evidence of akinete production in response to limiting phosphorus but the effect was not consistent for all strains tested. Low temperature, temperature shock treatment, anaerobia, low salinity stress, and light intensity extremes had no effect on akinete production. Differentiation appeared to be actively inhibited by blue and short duration UV light but significantly promoted by red and white light rich in red wavelengths. Similarly to the results for differentiation, the optimal temperatures for germination matched those for vegetative growth. Akinetes remained viable but didn\'t germinate at the lower temperature extremes (5 0C) and were killed at high temperatures (40 0C). Both the light quality history during differentiation and the actual germination light quality had no influence on germination frequency but germling growth was favoured by white light enriched in red wavelengths. We observed germination after 24 hours under anaerobic/microaerobic conditions but this was followed by zero survival. Germling cell growth rates were greater than those measured for vegetative cells across a range of germination experiments. The implications for these results on bloom dynamics will be discussed.