Seven years ago, a toxic form of algae bloomed in Milford Lake near Junction City. Kansas had never really seen a bloom quite like it before. It lasted for almost three months and has returned every summer since.
The event set state scientists looking for what spurred the blue-green algae, scientifically known as cyanobacteria, and how to stop the return of what is essentially killer pond scum.
“We’re trying to figure out what got Milford going,” said Trevor Flynn of the Kansas Department of Health and Environment. “That seems to be the million dollar question.”
Since then, the department has confirmed cases of toxic blue-green algae in dozens of lakes and ponds across Kansas.
The blooms aren’t just a nuisance because they look gross. They can get people sick. Common symptoms include diarrhea, vomiting, and hives. For some animals, the blooms have been deadly.
“So, that’s a real detriment to not only the water quality, but for the enjoyment of the people who are wanting to use it for recreation,” Flynn said.
After emerging early this decade for the first time since state health officials can remember, harmful algal blooms now happen in lakes and ponds across Kansas regularly.
Health officials only know the basics about what’s causing them: too many nutrients, such as nitrogen and phosphorus, that get into the water system when heavy rains wash fertilizer off farm fields.
University of Kansas researchers want to know more. They’re conducting the largest study of its kind to figure out just what it takes to trigger a harmful algae bloom in the wild.
At one of the ponds, KU biologist Ted Harris hovers over several round fiberglass tanks, each about 10 feet across and 6 feet deep.
The tanks are filled mostly with water from one of the reservoirs at the field station, but Harris also put in about 42 gallons of water from either Milford Lake or Marion Reservoir. Each lake has had significant harmful algae blooms the past several years. The added water will introduce those species into the tanks.
Researchers generally know why blooms happen. But they don’t know why some blooms are made up of toxic cyanobacteria and others aren’t.
Harris suspects it has to do with the balance of nutrients in the water. Specifically, he thinks chemically reduced forms of nitrogen, like ammonia, might lead to toxic blooms.
So Harris and his team add different combinations of nutrients to the tanks. Some get phosphorus, some get nitrogen, and others get combinations of both.
When researchers first started the experiment, the water in the tanks was clear enough that you could see all the way to the bottom. But after 17 days of adding nutrients, algal blooms take hold.
But not all of the tanks with algae blooms have toxic blue-green algae. And for the average lake goer, telling the difference can be difficult.
“You can just see a little bit of color differentiation,” Harris said. “But if you’re the average person you go, ‘I don’t know. It looks like pond scum to me.’ Right? So that’s why … if you see a big bloom, stay away from them just to be safe.”
Beyond color difference, blue-green algae also act differently. Cyanobacteria have a sticky substance that keeps them in balls, which allows them to form large surface scums. They also float right on top of the water.
Nature’s petri dish
An experiment about algal blooms of this scale has never been done before. Usually, they’re conducted inside a laboratory fish tank. That’s cheaper, takes less work, and if it fails, you just dump the tank out, clean it and start all over again.
Small-scale studies are easy to repeat, but they don’t test real-world conditions.
“This is what would happen in sort of repeated rain events,” Harris said.
The experiments run for 21 days, each tank gathering data on water temperature, light levels, and sediment changes all in the hopes of finding some nugget of information to better understand what causes toxic blooms.
If that puzzle is solved, health officials and water manager can find ways to stop poisonous algae before it blooms.
“Maybe we can go from a reactive, of, ‘Hey, this toxic bloom is here and my dog is really suffering now I need to go to the vet, what’s happening,’” Harris said, “to, ‘Hey, watch out, this lake has a bloom or it will have a bloom in the next few weeks.’”
Brian Grimmett, based at KMUW in Wichita, is a reporter focusing on the environment and energy for the Kansas News Service, a collaboration of KMUW, Kansas Public Radio, KCUR and High Plains Public Radio covering health, education and politics. Follow him on Twitter @briangrimmett.
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