RENEE MONTAGNE, host:
Many streams have been invaded by a very slimy algae. It's commonly known as rock snot and it's been spreading through the western part of the country for at least a decade. This year it went national.
NPR's John Nielsen has the story.
JOHN NIELSEN: Rock snot blooms began when a microscopic Dr. Jekyll turned into a Mr. Hyde. Ecologist Sarah Spaulding of the U.S. Geological Survey says this change begins when one-celled organisms called diatoms attach themselves to stream rocks, then gigantic slimy stocks burst out of the cells into the water.
Dr. SARAH SPAULDING (U.S. Geological Survey): So here's where the snot comes in. It makes a mucopolysaccharide stock, so this is essentially slime, and it can be hundreds of times the length of the cell, and that's what really causes all the problems.
NIELSEN: Rock snot blooms can blanket pristine stream beds with thick wads of goo that kill the bugs that big fish like to eat.
Angler Paul Dresher says these blooms can stretch for miles.
Mr. PAUL DRESHER (Fisherman): You put a lot in the water and try to reel back in and you end up with a giant wad of white, gooey, cottony material on the end of it. And it makes it essentially unfishable.
NIELSEN: Until the 1990s, blooms like these are few and far between in North America. Researcher Sarah Spaulding says the diatom that made them, didymosphenia geminate, or didymo for short, were so that researchers went to great lengths just to see one.
Dr. SPAULDING: People would say we ought to rent a van and drive to Lake Superior so we can get some didymosphenia in our collection. So it was something that was a trophy and didymosphenia is especially beautiful when you look at it through the microscope.
NIELSEN: But then something happened and the diatoms got more explosive and more aggressive. Researchers like Andrea Kirkwood of the University of Calgary say it may have been a more aggressive European strain of didymo that was accidentally brought to Canada.
Dr. ANDREA KIRKWOOD (University of Calgary): Or some sort of genetic event, an even where something happened in the species itself that now allows these massive growth formations that we see in cool, cold water habitats.
NIELSEN: In any case, it wasn't long before big blooms of didymo were mucking up prize fishing streams in western states like Idaho, Wyoming and Colorado. And then last summer, rock snot showed up for the first time in New England.
Leslie Matthews, a scientist with the state of Vermont, says it slimed at the Connecticut River in June.
Dr. LESLIE MATTHEWS (Vermont Agency of Natural Resources): We had an infestation that covered miles of the river and was two or three centimeters thick and bank to bank.
NIELSEN: Before the summer ended, similar didymo blooms had fouled streams in New York, New Hampshire, Tennessee, Missouri and Virginia. Fisherman Paul Dresher of New Hampshire says there's one thing that is now clear: anglers who move from stream to stream have helped spread these blooms around.
Mr. DRESHER: The anglers and recreationists travel worldwide now and when they bring their equipment back and don't adequately sanitize it, they run the risk of spreading this material, and that's pretty certainly how it got into northern New England.
NIELSEN: And to all those western states and into well-known fishing streams half a world away on the south island of New Zealand. Experts say there's no good way to stop an established rock snot bloom, but officials in New England say they are hoping to slow the rate at which the blooms are spreading.
Fisherman Paul Dresher says they've done it partly by posting lots of signs that urge anglers to clean and dry their boots and gear.
Mr. DRESHER: So if you travel around northern New England right now, you're going to find these little posters nailed to telephone poles and trees at every spot where anglers know other anglers go, telling them don't spread rock snot.
NIELSEN: Is that what they say, stop rock snot?
Mr. DRESHER: That's what it says.
(Soundbite of laughter)
Mr. DRESHER: It catches people's attention.
NIELSEN: Whether these signs will do any good won't be known until early next spring, when scientists go out looking for new rock snot hotspots.
John Nielsen, NPR News, Washington. Transcript provided by NPR, Copyright NPR.
For at least a decade, nasty carpets of an invasive algae species have been fouling up pristine fishing streams in the western United States. But this year, the giant, gooey wads appeared on the East Coast, and traveling fishermen are the culprits.
A rock snot bloom can cover a stream from bank to bank and reach for miles.
Serious fly fishermen may remember 2007 as the year that the invasive species known as "rock snot" turned into a national problem. For at a least decade, nasty carpets of this algae have been fouling up pristine fishing streams in the western United States. Then, last summer, it turned up in fishing streams in several eastern states.
Angler Paul Doscher of New Hampshire says it's useless to cast fishing lines into these sometimes giant blooms.
"You try to reel it back in, and you end up with a giant gooey cottony wad (on your hook)," he said. "There is nothing like that that I have experienced. It makes streams essentially unfishable."
Isolated Nuisance to Uncontrollable Monster
Twenty years ago, a mild version of the one-celled diatom that pumps out rock-snot blooms was found only in isolated mountain streams in western Canada. But in the 1980s, these blooms started getting larger and spreading into other streams.
"Something changed the diatoms in ways that made them more aggressive," said researcher Andrea Kirkwood of the University of Calgary. She says the change may have taken place when a European version of the rock snot diatom was accidentally brought to Canada. Kirkwood says it's also possible that the native version of this algae evolved in ways that created much more massive and more frequent blooms.
What's certain is that by the early 1990s, massive rock snot blooms were fouling cold, clear rocky mountain streams in western states such as Idaho, Wyoming and Colorado. Infestations sometimes stretched from bank to bank and covered several miles. Once the blooms appeared, it was impossible to make them go away.
East Coast Invasion
Rock snot seemed to be a strictly western problem until this past June, when a massive bloom appeared on the New Hampshire side of the Connecticut River. Before the summer, slimy carpets had fouled pristine fishing streams in New York, Vermont, Tennessee, Missouri and Virginia.
Anglers like Paul Doscher say it's now clear that fishermen who don't clean and dry their boots and fishing rods have helped spread these nasty blooms.
"The reality is that anglers and recreationists travel worldwide now to do what they do," he said. "When they travel they bring their equipment with them. Some of us don't sanitize that equipment properly when we're done fishing."
Doscher says he has no doubt that this is how the rock snot blooms got spread around the country. He also suspects that sloppy fishermen helped carry rock snot diatoms to streams on the south island of New Zealand.
Officials in New England have been posting signs near fishing streams that urge visiting anglers to clean and dry their gear.
"You find them nailed to trees near streams where anglers go," says Doscher. "They tell fishermen to 'Stop the rock snot.'
Whether these signs do any good won't be known until early next spring when scientists around the country begin looking for new rock snot hot spots.