Biologist Weighs in on Toxic Cyanobacteria Blooms


The following Q&A transcript on harmful cyanobacteria blooms was provided by the New Hampshire Lakes Association and New Hampshire Public Radio.

It’s now common for the New Hampshire Department of Environmental Services to issue advisories each summer, warning swimmers of bacterial blooms along northeastern beaches.

Cyanobacteria, also known as blue-green algae, has become prevalent throughout the Northeast. Now researchers from Dartmouth, the University of New Hampshire, and the Cary Institute of Ecosystem Studies are collaborating with the Lake Sunapee Protective Association to find out why.

David Lutz, a research associate at Dartmouth, is leading the team. He spoke with Morning Edition Host Rick Ganley by phone. A lightly edited transcript of the interview follows:

If I was visiting a lake in the Granite State and saw a bloom, what exactly would I be looking at?

You’d be looking at colonies of cyanobacteria. The blooms occur when conditions are very warm and there isn’t much mixing of the water—so there’s not too much wind to move them around, because they kind of can’t swim by themselves.

Do we find these blooms more often in places where there’s a lot of industrial farming, such as large factory farms?

There’s been an extensive amount of research on farms in the Midwest, or the Southeast or in coasts by cities seeing other types of blooms. Here in New Hampshire, we don’t have those kinds of landscapes as extensively. We’re mostly looking at lakes that are surrounded by forests, or second homes or kind of suburban or rural communities. Yet what we’re starting to see over the past decade or so are more of these blooms showing up. And so now is a really critical time for us to figure out what’s going on. We don’t have the same kinds of systems as they do in the Midwest, but we’re having these blooms and we really want to know why.


So you’re trying to find out that data. But we know that these blooms are more prevalent than they were in the past.

That’s correct. I’ll be candid and say that [the problem] is not quite as extensive as it is out in the Midwest, but it’s beginning to happen. And the fear is that unless we start to take action and do something about this, and understand the science of why it is happening, and which lakes are susceptible, we’ll have some bigger problems on our hands.


The advisories issued by state biologists every summer often say that blooms can cause multiple irritations: vomiting, mild fever, skin rashes. How harmful are they actually to swimmers?

There are a handful of different species of these organisms, some of which are maybe a little slimy to swim through, but may not carry toxins that are released. And some of them, if you do swim through them, they can cause skin irritations or you’re going to want to go to the hospital and get checked out. The lake advisories are generally issued when they have identified blooms that are particularly toxic and really harmful. So they’re normally focused on very life-threatening cases.


So not every bloom is necessarily toxic to people?

That’s right. In any event, even if the blooms aren’t toxic, they do have an effect on people around lakes. They have an adverse effect on tourism, on property values because of the aesthetics associated [with the blooms]. People generally don’t want to look at lakes that are green and covered in goopy cyanobacteria. So all these blooms are problematic.


As you pointed out, these blooms can have a real economic impact on communities around the lakes.

Yes. We have so many people who visit our lakes, who have second homes on and around our lakes, communities around lakes that depend on people coming and visiting. And these blooms are quite challenging because they really decrease the total numbers of people who visit.


What do you hope will come from this research at the end?

As I said, we’re kind of uncertain as to why these blooms are happening in some of these lakes. And one of the main objectives is to say, okay, well here’s at least a little bit of our understanding of which ones may be more or less impacted and may be more or less impacted in the future, especially as things get warmer, dryer. We have kind of warm spells like we did the past week or so and there were more blooms. We really want to understand which ones are more vulnerable or not. The other part is using drones and satellite technology to help us monitor where these blooms are occurring. Obviously that’s important for issuing advisories, but it’s also important for people who manage lakes. Lake protective associations may be able to use this technology in the future to go around and notify homeowners if there’s a bloom there much more quickly than before.