Jun 12, 2010 at 6:40 am #1260057
Ken LarsonBPL Member
@kenlarsonLocale: Western Michigan
Blue-Green algae (Cyanobacteria) is another “threat” that lurks in the water that has not been spoken to in the BP Forms concerning “bugs” that you may run into in the outdoor environment waters and should have knowledge about since it is showing up in waters during the months of August and September in certain areas of the US. ( eg. Cyanobacteria has been found in inland lakes on Isle Royale National Park for the last two years. In both years hikers were advised to bypass those areas and not use the waters in any form. ) I have posted some information below that might be helpful concerning this issue.
What are cyanobacteria?
Cyanobacteria is the scientific name for blue-green algae, or "pond scum." The first recognized species were blue-green in color, which is how the algae got their name. Species identified since range in color 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 the United States and 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.
Does the presence of a cyanobacterial bloom always mean the water is contaminated?
Researchers generally agree that between 30 and 50 per cent of cyanobacterial blooms are harmless because they contain only non-toxic species of freshwater cyanobacteria. Blooms containing even one species of toxic cyanobacteria will be poisonous and potentially dangerous. Because there's no obvious way to tell if a particular bloom is toxic, samples have to be analyzed in a laboratory before a body of water can be declared safe.
How likely am I to drink water contaminated with cyanobacteria and/or its toxins?
Relatively few incidents of human poisoning have been reported. People don't usually drink water contaminated with cyanobacteria because of the scum and the accompanying smell (fresh blooms smell like newly mown grass; older blooms smell like rotting garbage). However, people could unknowingly drink water containing cyanobacterial toxins released from blooms that have died naturally.
What about using contaminated water for washing?
If there is a safe source of water available, don't use contaminated water for washing clothes or dishes. If no alternative supply is available, use rubber gloves to avoid direct contact with the water. Bathing or showering in contaminated water should be avoided, as skin contact with the algae can lead to skin irritation and rashes.
Can water containing cyanobacterial blooms be used for recreational activities?
Unlike controls available with a drinking water source contaminated with cyanobacteria, there are very few options available once these algae accumulate in water used for recreational activities, such as swimming, boating, wind surfing and fishing. Blooms in recreational bodies of water are usually associated with unpleasant odors and offensive appearance on shorelines as the scum accumulates and decays. Although cyanobacterial toxins are probably not absorbed through the skin, they can cause skin irritation. The toxins, if present, can be absorbed from the water via ingestion or can become airborne and be absorbed via inhalation. Individuals should avoid swimming and other water-related activities in areas with dense blooms.
Can I cook using water with blue-green algae in it?
Boiling, chemical treatment, UV treatment or mechanical filtration of water DOES NOT remove toxins from the water. As it is impossible to detect the presence of toxins in the water by taste, odor or appearance, you must assume that they are present until testing is completedJun 12, 2010 at 7:08 am #1619269
@figsterLocale: Central Arkansas
Thank you!Jun 12, 2010 at 7:45 am #1619274
Ken T.BPL Member
Kills dogs quickly also. We had a few deaths out here the past few seasons.Jun 12, 2010 at 9:30 am #1619301
Michael RayBPL Member
> However, people could unknowingly drink water containing cyanobacterial toxins released from blooms that have died naturally.
How long do the toxins last or should we just never drink from a pond/lake (does size matter?) in late summer/early fall unless the owner says it's been tested as clean? I've certainly seen my share of pond scum in Indiana.Jun 12, 2010 at 10:28 am #1619313
Ken LarsonBPL Member
@kenlarsonLocale: Western Michigan
People should suspect that blue-green algae could be present in water that is visibly discolored or that has surface scums.
A blue-green algae bloom:
• Often looks like green paint floating on the
• Is made up of extremely small organisms that
are hard to pick up or hold.
• Can be bright green, or bluish, brownish, or
• Is most common in the summer and fall but
can occur anytime.
Is the water always toxic if the algae is present?
As cells die, toxins are released into surrounding waters. Some toxins, such as microcystins, are very stable and can remain in the water for days or weeks after the bloom has disappeared. Over time, these toxins are diluted and eventually break down and disappear.
CAUTION SHOULD BE TAKEN!Jun 12, 2010 at 10:31 am #1619314
is safe correct?Jun 12, 2010 at 10:52 am #1619317
@bcrowellLocale: Southern California
Michael wrote: "How long do the toxins last or should we just never drink from a pond/lake (does size matter?) "
"Drinking water from a lake is best advised at the inlet, with the next best place at the hopefully fast-flowing outlet."
This is referring to giardia, but I think th advice is probably valid regardless of what contaminant you're worried about.
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