OSU scientists say toxic algae can migrate from reservoirs.
Toxic blue-green algae blooms can slip through dams and ride rivers all the way to the ocean, Oregon State University researchers said Tuesday.
Scientists used genetic tracking tools to follow the sometimes-toxic bits of algae bloom for 180 miles from an Oregon mountain reservoir to where the river flows into the sea, a study said.
"It will be a bit of a surprise," OSU researcher Timothy Otten said, because most people don't think of algae blooms in running water. In Oregon and elsewhere, the blooms typically occur in the still waters of lakes and reservoirs, especially during hot weather. But from there, the algae can flow and survive all the way to the ocean.
The trouble comes in the estuaries where freshwater mussels filter the sea-bound waters and accumulate the toxins. Mammals, including people, eat the mussels.
Researchers at Morro Bay, Calif., two summers ago noted that sea otters in the saltwater bay inexplicably began dying of a freshwater toxin, microcystin, the same one OSU scientists found riding Oregon rivers.
The Morro Bay otters subsist on mussels.
The researchers tracked the toxin upstream 2 1/2 miles to Pinto Lake, which is notorious for its periodic blue-green turns.
Such incidents are an increasing worry for wildlife managers and human health officials.
The frequency, duration and magnitude of harmful algae blooms appear to be increasing, according to Otten and OSU professor Theo Dreher, a microbiolo gist who studies cyanobacteria, the organisms that form the blue-green blooms.
Dams that form still pools, coupled with rising temperatures and atmospheric carbon dioxide concentrations, extreme weather and increased runoff of nutrients from urban and agricultural lands are all compounding the problem, according to the researchers.
Of 123,000 U.S. lakes larger than 10 acres, about one-third contain toxin- producing cyanobacteria, according to the Environmental Protection Agency.
"Behind a lot of reservoirs all over the world, this is a big problem," Otten said.
Saltwater algae blooms are getting bigger, more frequent and surprisingly deadly, according to researchers.
Last summer, near Monterey, Calif., a marine algae bloom tainted sardines and anchovies and gave the sea lions that ate them seizures, which rescuers quelled with phenobarbital shots.
Of the rescued animals, 200 were sickened and 50 died, according to news coverage.
The OSU scientists tested for microcystin- bearing algae blooms in the Iron Gate Reservoir on the Klamath River through a season.
In 2012, they took 120 samples from 16 sites between the reservoir and the river outflow in Northern California.
The transport of algae has been little studied, even though it's likely common, the researchers said.
They found that the toxins can survive passage through hydroelectric turbines, hundreds of miles of river and become a hazard for people, pets and wildlife downriver.
"Even in flowing rivers, you can't assume that cyanobacteria aren't going to be there because they may be passing through," Otten said.
In an estuary, freshwater mussels can accumulate more than 100 times the toxin than what researchers would find in nearby water samples.
"You can have enough toxin in a shellfish that it's a health concern," Otten said, adding that the Yurok and Karuk tribes harvest the mussels downriver.
Oregon's Department of Agriculture does not test for the kind of cyano bacteria that grows in a lake, Otten said.
"They aren't looking for freshwater toxins in the shellfish. That's one of the concerns," he said.
The Klamath River system is nothing special with regard to production and transport of algae blooms.
The blooms are common in Lane County reservoirs such as Dexter, Dorena and Fern Ridge, which are drained by the middle fork of the Willamette River, Row River and the Long Tom River, respectively. The water all flows north in the Willamette to Portland.
The Oregon Health Authority warns that swimmers and other water users can be sickened if exposed to toxic algae blooms.
Exposure can cause brain and liver damage, rashes and gastrointestinal illness.
"On a lake or river, if you see a green band along the shore or green scum on the surface, the water may not be safe to recreate in," Otten said.
Findings of the OSU study, just published in the Harmful Algae professional journal, are likely to give impetus to calls for more testing of algae blooms at popular reservoirs and downstream, where the bloom bits flow.
In May, however, the U.S. Army Corps of Engineers announced it would no longer test algae blooms at the reservoirs it manages, including at the popular Lane County reservoirs.
Scientists are now employing cheaper, faster and more comprehensive tests to identify the potential toxicity in a bloom by measuring its genetic content, Otten said.
The genetic test costs $75 per sample, compared with the typical cell count tests that cost as much as $350 or the alternative toxin assays that range up to $400, he said.
"You can bury your head in the sand and say, 'We're not going to worry about it, or you can try to characterize the risk,' " he said.
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WHAT TO WATCH FOR
Blooms: Algae blooms look foamy, scummy or thick like paint, and are blue-green, brownish red, pea green or white; they also can be a dark green or black slimy mat with an offensive odor.
Warning: Stay out of the water and keep children and pets away. Never drink or cook with affected water. In event of contact, wash it off thoroughly with clean water and soap. Neither personal filtration devices nor boiling makes the water safe.
More information: Oregon Health Authority, 1.usa.gov/1yi2FZF
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|Publication:||The Register-Guard (Eugene, OR)|
|Date:||Jun 17, 2015|
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