The detrimental effects of a harmful algal bloom can range from cell and tissue damage to organism mortality, and can be caused by a number of mechanisms, including toxin production, predation, particle irritation, induced starvation, and localized anoxic conditions. As a result, a bloom may affect many living organisms of the coastal ecosystem, from zooplankton to fish larvae to people. The toxins produced by HAB. As noted above, only a few HAB species actually produce toxins that are poisonous to people and marine animals. The most well known HAB toxins are generically referred to as ciguatera fish poisoning (CFP), neurotoxic shellfish poisoning NSP), paralytic shellfish poisoning (PSP), diarrheic shellfish poisoning (DSP), and amnesic shellfish poisoning (ASP). Pfiesteria piscicida also produces two toxic fractions, dermonecrotic and neurologic toxins that impact fishes and humans (Bever et al. 1998, Grattan et al. 1998) (Lowitt and Kauffman 1998) (Noga et al. 1996).
Cyanobacteria also produce similar toxins that overlap with several of these general categories, including neurotoxins and hepatoxins. Symptoms of exposure to these toxins include gastrointestinal, neurological, cardiovascular, and hepatological symptoms. The algae that produce these toxins, and the specific symptoms they cause, are summarized in Appendix A. The terms "fish" and "shellfish" are associated with these illnesses because the toxins concentrate in the fish and shellfish that ingest the harmful algae; people and marine mammals may be poisoned when they consume the affected seafoods.
Other harmful algal blooms produce toxins with no identifiable effects on humans but devastating impacts on coastal living resources. For example, the flagellate Heterosigma akashiwo is thought to produce an ichthyotoxin that kills fish
http://www.freedrinkingwater.com/water_quality/quality1/1-toxic-aglae.htmWhat are cyanobacteria?
Cyanobacteria is the scientific name for blue-green algae, or "pond scum." The first recognized species were blue-green in colour, which is how the algae got their name. Species identified since range in colour from olive-green to red.
Cyanobacteria form in shallow, warm, slow-moving or still water. They are made up of cells, which can house poisons called cyanobacterial toxins. A mass of cyanobacteria in a body of water is called a bloom. When this mass rises to the surface of the water, it is known as surface scum or a surface water bloom. Although we don't know the extent to which cyanobacterial blooms occur across Canada, we do know they mostly appear in the hot summer months and are quite prevalent in the prairies.
What are cyanobacterial toxins?
Cyanobacterial toxins are the naturally produced poisons stored in the cells of certain species of cyanobacteria. These toxins fall into various categories. Some are known to attack the liver (hepatotoxins) or the nervous system (neurotoxins); others simply irritate the skin. These toxins are usually released into water when the cells rupture or die. Health Canada scientists are more concerned about hepatotoxins than neurotoxins, because neurotoxins are not considered to be as widespread as hepatotoxins in water supplies. Very few cyanobacterial toxins have actually been isolated and characterized to date. Better methods of detection are being developed to help us learn more about them, especially to find out which toxins are a problem in Canada and what conditions encourage their production.
http://www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/cyanobacter-eng.phpWhat ever ........ drink it if its moldy