3. INVASIVE SPECIES: Spread of algae poses threats to waterways, parks, fisheries (Land Letter, 07/24/2008)

Scott Streater, special to Land Letter

On a warm June morning last year, Lawton Weber carefully stepped into the Connecticut River in Vermont and plopped a raft into the water. The plan was for Weber, a professional fly-fishing guide, and a friend to spend the day on the river, fishing for trout.

But when Weber looked down, he noticed the rocks and gravel on the river bottom were covered with a gooey-looking brown substance. He knew immediately that it was a type of freshwater algae referred to by its revolting but appropriate nickname -- "rock snot." And he knew that when it blooms, the algae can blanket the bottom of rivers and streams for miles, snuffing out aquatic insects and other microinvertebrates that fish depend on for food.

"I thought, 'Whoa, this is not good,'" said Weber, who had seen the algae on a fishing trip to New Zealand, where in the four years since its discovery, it has caused an environmental and economic catastrophe.

Weber's discovery marked the first time that Didymosphenia geminata -- referred to as didymo, for short -- had been seen in Vermont, and it set off a wave of concern among anglers and state regulators that the algae could drive away the rainbow and brown trout that make the Connecticut River and other area waterways a fishing mecca. Within a week, the algae was found in several other spots on the Connecticut and the White River in New Hampshire. Continuing its course, the algae was found a month later in the Batten Kill in New York -- a celebrated trout stream also popular with kayakers and tubers that meanders 29 miles from Vermont to the Hudson River.

The outbreak brought national attention to the emerging problem of didymo, which is spreading across the United States at a breakneck pace, leaving anglers worried and scientists puzzled.

For decades, the slimy-looking algae had been confined to cold, nutrient-poor rivers, creeks and streams mostly in Canada. But for reasons that researchers cannot explain, it is spreading rapidly south and is now found across northern California, Colorado, Idaho, Montana and Washington. In the past two years, it has turned up in waterways as far south as Arkansas, North Carolina and Tennessee.

"I think it's something we're just going to have to live with for a while," said Erica Shelby, a water use and resource specialist with the Arkansas Department of Environmental Quality. "It's ugly and it's here."

A threat to fish populations

For now, the problem remains an aesthetic one, but larger problems loom on the horizon. The main concern is what impact the algae could have on fish populations, since the blooms smother the sources of food for fish, driving them away.

A January 2007 EPA "white paper" on didymo warned that the spread of the algae could create "a significant strain on regional and national economies" by affecting tourism and fisheries. "If the favored food sources for fish are impacted in a negative way," according to the report, "fish will also be impacted negatively."

Example: A massive didymo bloom in Rapid Creek in western South Dakota in 2002 is suspected of having driven away an estimated 90 percent of the brown trout in the creek. So far, the overall effects to fisheries have been small because the fish simply swim away to areas where the algae has not yet bloomed. But as the algae spreads, the escape options for fish decline.

Researchers believe the spread of didymo is due mostly to boaters and anglers, particularly fly-fishers who wade out into the water. The microscopic algae can live for as long as a month outside the water, hiding in the damp crevices of felt-soled waders. If the waders and other equipment are not washed thoroughly before the next fishing trip, the didymo spreads.

Once didymo has invaded a waterway, there is no effective way to get rid of it. The best option is to try to contain its spread. Officials in Vermont, New Hampshire and New York in the past year have launched a massive public education program to encourage boaters and anglers to wash their boats, paddles, kayaks and fishing gear before entering another waterway.

But didymo continues its relentless march south. In May, the Maryland Department of Natural Resources announced that didymo had been found by anglers in Gunpowder Falls in Baltimore County. And more recently, didymo turned up in the Elk River near Webster Springs in West Virginia.

Didymo may be much more widespread than anyone knows, because there is no national effort to map where the nuisance organism has been found, said Sarah Spaulding, an ecologist with the U.S. Geological Survey in Denver, and the lead author of the EPA white paper on didymo.

"What we have now are people saying, 'Well there's a bunch of it over here, and it's a problem,'" she said.

Threats to national parks

The National Park Service is growing increasingly concerned about didymo's spread.

Didymo was discovered last year in Lake Creek in the Grand Teton National Park in Wyoming, and it is suspected of spreading to the Snake River, a popular trout-fishing waterway in the park, said Susan O'Ney, a National Park Service resource biologist at Grand Teton.

O'Ney and a team of researchers with U.S. EPA and USGS next month will conduct a survey of the Snake River and its tributaries within the park to determine the extent of the problem.

"We're very concerned about aquatic invasive species," O'Ney said. "I hope we don't find much more of it in the park."

The fear is that they will, both at Grand Teton and other national parks.

The National Park Service's Natural Resource Program Center in Fort Collins, Colo., recently put together a brochure to assist park managers in recognizing didymo and reporting it, said John Wullschleger, a fishery biologist at the center.

"I suspect it's going to be one of those things on our radar screen, in terms of tracking and monitoring it," he said.

A mysterious organism

Didymosphenia geminata is a type of one-celled organism called a diatom, which is found in virtually all marine and freshwater environments. Despite recent discoveries, didymo is still found mostly in cooler waters and is very common in Scotland, Sweden, Finland and northern China.

The algae was first discovered on the Faroe Islands, north of Scotland, in the early 19th century. It was discovered in North America in the late 1800s on Vancouver Island, British Columbia. Over the decades, it steadily spread across Canada but was slow to make its way into the U.S. waterways. A 1975 study by the Academy of Natural Sciences of Philadelphia listed Virginia as the only state where didymo had been found. By the mid-1990s, however, didymo was routinely found across the Northeast and Northwest.

Rock snot is as ugly as its name implies. Photo courtesy of the Maine Bureau of Land and Water Quality.

During algal blooms, it attaches itself to rocks using stalks that form thick mats that can cover river, stream and creek beds for miles. The mats are usually colored brown, yellow or white, and though they look gooey -- as the "rock snot" nickname implies -- the algae actually feels like cotton or wool. Blooms can last for months at a time. These algal blankets sometimes form thick white trailers, resembling long, thin strips of toilet paper. In fact, it is not uncommon for the algae to be mistakenly reported as a sewage spill.

That is what happened when the massive bloom was discovered six years ago in South Dakota's Rapid Creek.

"When we got there it looked like the bottom of the creek was covered with toilet paper," said Karl Hermann, regional water quality monitoring and assessment coordinator at the EPA's regional office in Denver. "That's initially why we were called. But it turned out that it was all biological."

Today, the didymo in Rapid Creek blooms every year, with the algae covering a 6-mile swath of creek bottom for up to four months at a time.

No one is sure what triggers blooms, though most are caused by an overload of nutrients, such as fertilizers from yards or sewage from treatment plants, that get washed by the rain into waterways. But didymo has bewildered scientists, showing a remarkable ability to grow rapidly in low-nutrient water that should not be able to sustain the massive blooms.

Perhaps the biggest mystery is why the algae have moved to -- and thrive in -- warmer waters. Until recently, the one common element when didymo was found was that it appeared in colder, nutrient-poor waters, such as mountain streams. But in the last five years, didymo has been found increasingly in warmer waters, as far south as the White River in Arkansas.

For these reasons and others, Spaulding and her colleagues concluded in the EPA white paper last year that didymo remains "an organism for which we lack basic biological and ecological knowledge."

"On a scientific level, this algae is kind of fascinating," said Leah Elwell, conservation coordinator of the Federation of Fly Fishers and the co-author of the EPA white paper with Spaulding. "But in the real world, it's scary. Particularly because there are so many things about it that we do not know."

A super strain?

Federal grants to study the issue are hard to come by, researchers say, because didymo is considered a native species to North America, even if it is not native to many states where it is now found. As a result, it has been classified as a nuisance species rather than a non-native invasive species, despite the potentially devastating effects.

But one theory that is gaining traction is that the didymo that's native to North America accidentally mixed at some point with a strain of the species accidentally brought here from Europe, mutating into a new super-strain of didymo.

"That's certainly a possibility," Spaulding said. "If that turns out to be true, then we would be talking about a non-native invasive species. But no one has done the work yet to figure that out."

In New Zealand, where didymo is considered a non-native species likely transported from North America, the government is spending hundreds of millions of dollars to map it and devise tools to fight it. New Zealand researchers have been experimenting with a chelated copper mixture that appears to be extremely effective. But, unfortunately, it cannot kill all the algae, and even a water drop is enough to spark another algal bloom the next season. The New Zealand government has concluded there is no way to completely eradicate didymo once it is in a water system.

Until an effective system to eradicate didymo is devised, the best thing that can be done is to try and contain its spread.

"One of the frustrating things is that it's going to keep spreading," Spaulding said. "Let's learn that it's going to be spreading instead of panicking the next time it shows up."

Panic in Vermont and New Hampshire

In fact, a sense of panic pervaded when Weber, the Vermont fly-fishing guide, discovered the algae in the upper Connecticut River, and later when it was found in the White River.

"I was shocked," said Mary Russ, executive director of the White River Partnership in Vermont, a community group that works to improve the health of the river. "For us, it's our mission and our goal to protect the river. It really sort of caused us to reconsider what we are doing and what our priorities are. Everything came screeching to a halt as we scratched our heads and wondered what this was."

No one was sure if the gooey-looking algae was harmful to humans (it's not), and no one was sure how it got into the Connecticut and White rivers. Most people suspect fly-fishers whose waders and other equipment were contaminated brought it into both rivers.

Officials in Vermont and New Hampshire, which share the Connecticut River, banded together to pay for radio advertisements and to post signs at public entrances warning anglers and boaters to clean their equipment with bleach or dishwashing detergent. "Some of the fishing lodges have even established cleaning stations so anglers can clean their equipment," said Scott Decker, program supervisor with the New Hampshire Fish and Game Department.

But Weber said he believes that not everyone is doing all they can.

"I'm not convinced the kayakers are getting the word out," he said. "They go from river to river, just like we do. The watercraft industry has their head in the sand, it seems. Maybe they don't care as much because even if didymo spreads, they'll still have water to play with."

Meanwhile, didymo continues to spread in Vermont and New Hampshire. This month, didymo was discovered in the Mad River, which drains into the White River in Vermont, and last month it was found in Locust Creek, a tributary of the White River.

Today, it is spread thick, bank-to-bank, in parts of the Connecticut and White rivers. "It is quite an obvious problem if you're on the river," said Amy Smagula, exotic species program coordinator for New Hampshire Department of Environmental Services.

Some fly-fishers have returned this year to the White and Connecticut rivers, careful to wash off their equipment before leaving; others, like David Deen, a Vermont fishing guide, have not.

"I'll tell you, right now the Upper Connecticut and White River are off my guide list," said Deen, who is also a Vermont state representative. "I don't want to have to even consider putting a wader in either river and spreading the stuff."

Scott Streater is a freelance journalist based in Colorado Springs, Colo.

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