Harmful algal bloom

A harmful algal bloom on Owasco Lake in Cayuga County is seen in the summer of 2017. The state is investing $500,000 to prevent algal blooms from becoming a problem in Lake George.

As a journalist, the term "harmful algal bloom" is kind of a pain.

That's because 1. they're really not algae, 2. they're not always harmful, and 3. most people used to call these things blue-green algae.

So what are they?

The scientifically correct term for harmful algal blooms is cyanobacteria. They're a photosynthesizing bacteria tending toward the bluish tint that sometimes produce toxins, most of which are bad for humans. They need nutrients, warm, calm waters and sun to grow. 

They tend to look like paint film or pea soup, depending on how dense the cells congregate. Some may even be benthic, meaning they appear on rocks or at the bottom of a water body.

They've also been around forever — well, not forever, but approximately 3.5 billion years. They helped create our oxygenated atmosphere, so it might seem ironic that one of the things that helped give us air to breathe is one of the things we're now afraid of. It's impossible to tell visually if a bloom has toxins or not, so state officials say it's best to just stay away.

The four most common toxins cyanobacteria produce in the United States are called microcystin, anatoxin, saxitoxin and cylindrospermopsin, according to the U.S. Environmental Protection Agency. Scientists are still researching why some cyanobacteria blooms are toxic and others are not.


Microcystins are the most common in blooms in the United States. They are primarily a liver toxin, but also can do damage to kidneys and the reproductive system. They are also a possible carcinogen in humans. They have been known to kill livestock and pets.


Anatoxins affect the central nervous system. They have been known to kill livestock, pets and waterfowl usually through respiratory paralysis. 


Saxitoxins are part of a group of toxins that cause Paralytic Shellfish Poisoning, which can involve gastrointestinal and neurological problems, paralysis and respiratory failure.


These primarily cause damage to the liver and kidneys. 

On a weekly basis, the state Department of Environmental Conservation updates a Harmful Algal Blooms Notifications Page. It shows where the state has been informed of cyanobacteria blooms, some which are "suspicious," meaning they haven't been tested for toxins, some which are "confirmed," meaning they have toxins, and some "confirmed with high toxins." 

In a chart, the DEC lists the affected water body, the status of the bloom, the extent of the bloom, its status date, whether it was reported visually or through a lab sample, and whether the status of the bloom has been updated, is new, or there has been no change.

So far, no water bodies in Warren, Washington or Saratoga counties have been added to the list this year.

— Gwendolyn Craig

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Reporter Gwendolyn Craig can be reached at 518-742-3238 or gcraig@poststar.com. Follow her on Twitter @gwendolynnn1


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