Bluegreen algae or cyanobacteria blooms are associated with hot, humid weather, negatively affecting the ecosystem and recreational resources. The phenomena has become more prevalent as climate change raises global temperatures.
University of Vermont Natural Resources PhD candidate Katelynn Warner studies cyanobacteria bloom dynamics in Lake Champlain. She is a co-author of a global studythat finds cyanobacteria blooms are also occurring in cold water. Warner tells WAMC North Country Bureau Chief Pat Bradley that UVM’s Rubenstein School of Environment and Natural Resources became involved in the study through a collaborative called the Global Lakes Ecological Observatory Network.
We focus on working groups. So there are collaborative projects that come out of it. So where this project came out of "Blooms like it cold" came out of a cyanobacteria working group specifically within this group called GLEON (Global Lakes Ecological Observatory Network). We were all sitting around brainstorming topics. And we cultivated this conversation about how we had noticed blooms occurring in cold waters, which isn't what our normal perspective of blooms is. So that's kind of how the project started.
In the study you note that you define a cold-water cyanobacterial bloom when it's observed when the water temperature is, and if I converted the Celsius degrees correctly, below 59 degrees Fahrenheit. A lot of people I think, would think 59 degrees isn't that cold a temperature of the water. Why is that the defining temperature?
If we look at laboratory experiments, and a lot of studies that have been done on cyanobacteria blooms previously, they show that cyanobacteria have really high growth, optimal growth, temperatures. So they really like high temperatures, like 25 degrees Celsius and higher, that's when their rates of growth tend to be the highest. And a lot of laboratory experiments show that growth slows down around 15 degrees Celsius, or they don't include anything colder than 15 degrees in their studies. We use 15 degrees essentially because of that. And then also because 15 degrees is around like late fall seasons and like early spring and then in the winter period,
How long have we been finding these cold-water algae blooms or have there been previous studies?
Right. One of the main topics that arise out of this paper was the fact that this has been historically under studied and that a lot of our sampling procedures or how we monitor essentially doesn't encapsulate this cold-water season. So it's hard to say how far back this was happening, if this has been a regular occurrence and we just haven't been seeing it or whatnot. So what this study shows us is that we need to expand that monitoring season because we recognize it was happening but we can't answer whether or not it's been happening for a really long time. Or if it's something new.
Why is everybody focused so much on the warm weather blooms? Is it just because they're more prevalent?
It could be because they're more prevalent. But I think a lot of it is because we have had this idea, or there's been this paradigm, that blooms like it hot. There's a bunch of research that suggests that blooms operate or grow fastest and most efficiently under higher temperatures. So because of that, that's how we've designed our summer sampling seasons. And because we're out in the water all the time noticing these blooms during this time. So I think that's why we sample more in the summer. And then also winter sampling can be a little bit more costly and there's a little bit more nuances around winter sampling, say getting a boat out in the lake and taking water samples.
What are some of the basic things that the study has determined so far about the cold-water blooms?
So like what type of mechanisms?
Yeah. How they form. If there are specific factors that create them that are different from summer cyanobacterial blooms. Is it the same type of phosphorus pollution that creates them in the winter as in the summer? I think you also mentioned in the study there are different species of cyanobacteria. Is it certain species that occur in the winter and perhaps not in the summer? Or are all of these still being determined?
Yeah, I think a lot of these questions still need to be fully determined. But briefly what we've seen is that sometimes a lot of the cyanobacteria species that we're seeing in the winter are actually the same ones that we're seeing in the summer months. And what that means is that cyanobacteria have this really wide temperature range that they can grow in. So some cyanobacteria really love cold water, not really love but like cold waters and can grow and sustain populations, albeit slowly in cold temperatures, such as under ice or winter water temperatures. And then that seed population can carry over into the summer and then the bloom can have a competitive advantage when the water and conditions start becoming more preferential for them.
Are the winter cyanobacteria blooms more or less toxic than the summer blooms or do we know yet?
I think that's a really interesting question and we don't know that yet. Mainly because of the limitations in our sampling methods and where we've been studying cyanobacteria blooms seasonally.
Katelynn, can you tell at this point in the research how at risk lakes across this region are to the cold water cyanobacterial blooms?
Yeah, that's a good question. I think that we can't really say for certain how high of a risk this is because we've seen it, maybe in a couple of lakes here in Vermont area or in this region. But that's because we've happened across them really. I think going forward in order to answer these types of questions we need to increase our methodologies and our sampling season so we could really encapsulate how often this is happening here and what lakes are really more subjective to these types of cold-water blooms.
Do we have any idea what the implications for cyanobacteria, aka algae bloom, management might be from this study that shows that we could have year round bloom growth and what might be needed to enhance any sort of management of them?
For lake managers and researchers alike, we really need to be able to increase that period of time that we're monitoring lakes in order to incorporate winter, late fall and early spring season. If we don't, we're probably missing a lot of early warning indicators of cyanobacteria blooms and a lot of important mechanisms that really promote their growth. So we're limiting our understanding of the mechanisms of cyanobacteria blooms if we don't incorporate these seasons into our sampling periods and research around blooms.
The researchers observed cold water cyanobacteria blooms in about 40 lakes across the globe.
