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Blue-Green Algae: It's A Thing

Sen. Christopher Bray is backing a per parcel fee on all property in Vermont to help fund water quality projects
the Vermont Department of Health
Scientists are still trying to wrap their heads around what exactly blue-green algae is and why it does what it does.

Another summer and more warnings about blue-green algae in Lake Champlain. Also known as cyanobacteria, it confounds lake users and confuses scientists. So what exactly is this stuff? Is it plant or bacterium? And why does it produce toxins sometimes and not others?

Aquatic Biologist Angela Shambaugh of the Department of Environmental Conservation's Watershed Management Division and Lake Champlain Committee Staff Scientist Mike Winslow tell us what we know and don't know about the scourge of our waterways. Here are some highlights:

“Blue-green Algae” Isn’t Really Algae

Cyanobacteria is just bacteria.

“There are folks that don’t like calling it an algae, but that really depends on your definition of algae is, and that definition has changed over time,” Winslow said. “Algae is definitely a photosynthetic organism, mainly living in the water, without roots, stems or leaves. On that, most scientists agree.

“Some people add on another piece of that that it has to have a certain sort of cell structure, and blue-green algae don’t meet that last criteria,” he said. “They’re a much more primitive organism. They don’t have - if you remember back to your high school biology class – they don’t have a nucleus, they don’t have organelles within the cell, so it’s a much more primitive structure.”

You Can’t Pick It Up With A Stick

“The [cyanobacteria] individuals are each microscopic,” Winslow said. “One of the ways that we teach our monitors how to determine whether they’re seeing a blue-green algae bloom is ‘If you can pick it up with a stick, it’s not blue-green algae.’ It’s some other sort of algae, some sort of other plant. It’s most similar to pollen. A lot of people have seen pollen on the water. It has that same sort of oily texture, you can’t pick up individual particles. It differs from pollen in its color. It doesn’t manifest as yellow.”

It Smells

It’s tricky to describe how the stuff smells because different people perceive it differently, Shambaugh said. “It’s described as earthy, fishy. It can be very pungent. I’ve been out on several blooms and you know definitely that you are moving through a blue-green algae area. It’s difficult to describe because it is a little bit different for every person, what they take away from that smell.”

What does Winslow take away from it? “Nothing I want to keep,” he said.

It’s, Like, Everywhere

“Lake Champlain is just one of the places it’s found,” Shambaugh said. “These are very common organisms. They’re native, they’re natural pretty much through the entire world. They can colonize extreme environments like hot springs, desert crusts – they’re very important in desert crusts – they can be found in the Antarctic. So pretty much any place that is the least little bit wet, standing water, flowing water, it’s possible that they’re there.”

The reason it doesn’t usually show up in most water (especially running water) is that cyanobacteria requires calm conditions with still water and little wind in order to form the visible scum at the top of the water.

It’s Toxic, But Only Sometimes

What’s up with that?

“We don’t know,” Winslow said.  “There’s a lot of questions about why they form the toxins, when they form the toxins, some species form them and others don’t, and even within a species some have the gene to produce the toxin and others don’t. They aren’t producing it as a toxin to defend against us or to chase us away. We don’t really know why they’re using it. It might be predator avoidance, it might be protection from the sun, it might be a signaling to other algae. There’s different ideas and different tests about that but nobody’s really sure why they’re making the toxins.”

Shambaugh said there are several groups of toxins cyanobacteria can produce.

“The most common one seems to be microcystin … it’s one of the more common ones that’s found. The other one that’s occurred on Lake Champlain in the past occasionally is called anatoxin. It’s a neurotoxin, can affect the nerves, whereas microcystin tends to affect the liver. And then there’s a third now that we’ve begun testing for here on Lake Champlain and it’s called cylindrospermopsin, which is also a nerve toxin I believe.”

Shambaugh said the toxins only have an affect if people (or pets) ingest cyanobacteria, though another compound generated by the bacteria can cause skin irritation. She also said the toxins produced by an individual cell aren’t harmful enough to cause health problems, and algae tends to be dangerous only in the form of a bloom, which is easily visible in the water.

Climate Change Is Making It Worse

An excess of phosphorus in the water feeds the cyanobacteria and is often blamed for the blooms of it in Lake Champlain and elsewhere, but Winslow said temperature plays a role too.

According to Winslow, “The other factor that really helps their growth is warm water. They do better when the water gets warmer, and we’ve certainly been experiencing hotter summers. Our surface water temperatures in August in Lake Champlain have increased by five to six degrees Fahrenheit and that promotes growth as well.”

He also said there’s been an increase in algae blooms worldwide, not just in Lake Champlain.

Also on the program, 17-year old Ash Brittenham and his mother Kim share thoughts on why it's important for outdoor recreational spaces to be accessible to all kinds of people. Ash lives with Duchenne muscular dystrophy and uses a wheelchair to get around. The Brittenhams say the 25th anniversary of the Americans with Disabilities Act this month is a good time to reflect on all the progress we've made but how far we still have to go to make sure that our public areas are welcoming and easy to maneuver through. Here are links to the ADA checklist and to Inclusive Vermont's database of places where people with disabilities can find out about accessible spaces in Vermont.

And we read your comments from our virtual mailbag.

Broadcast live on Thursday, July 16 at noon; rebroadcast at 7 p.m.