Local consequences of global warming predicted by Wisconsin scientists

October 31, 2010

By Michael Timm

Warmer, rainier winters and more intense storms would pose stormwater management challenge

When heavy rains and flooding collapsed an East Side manhole, turning an urban intersection into a sinkhole that swallowed a Cadillac Escalade, some people were probably wondering if Milwaukee’s July 22 storm was a freak event or a sign of things to come.

Scientists agree that no one can predict future weather with total confidence. But recently, Wisconsin scientists have “downscaled” global models of climate change onto the Badger State to prepare for the likely local impacts of predicted and observed trends—a gradual average annual temperature increase, warmer and rainier winters, and more intense storms.

“Our climate is variable; it has been changing; and we have not been managing our resources as if that’s the case,” said David Liebl, statewide stormwater specialist at the UW-Cooperative Extension and a member of the Wisconsin Initiative on Climate Change (WICCI).

“It’s interesting that in Wisconsin we’ve got regulation in stormwater quality but almost nothing about stormwater quantity.”
—David Liebl, statewide stormwater specialist

In an effort now being emulated across the continent, WICCI climate scientists Dan Vimont, Steve Vavrus, and Dave Lorenz developed a method to focus the global climate models assessed by the International Panel on Climate Change in 2007 onto a smaller geographic area, in our case, the upper Midwest.

WI downscaledA

Wisconsin climate scientists “downscaled” global climate models (left) to a scale more meaningful for Wisconsin (right), composed of data pixels eight kilometers square, to provide “a statistical range of probable climate change.”

What the Models Predict

models vs hist dataA

Wisconsin climate scientists tested their downscaled climate models against two decades of actual weather data. The models (14 colored lines) fit closely with observed temperatures from 1980 to 1999 (thick black line). The models were not as consistent predicting historical precipitation data for the same years.

Over the next half-century, the models predict an annual mean temperature increase of between 4 and 9 degrees Fahrenheit statewide. Warming is expected to be most pronounced during winter. The models also predicted a small, gradual increase in annual precipitation.

WI 2055 temp extremes

Over the next four decades, climate models predict a significant decrease in the number of below-zero winter nights and a significant increase in the number of over-90-degree summer days across Wisconsin.

But perhaps more important with regard to stormwater management, Liebl said, is that the models are in greater agreement about a precipitation increase in late winter and spring. “Most of flooding takes place in springtime,” Liebl said. “That’s not a good time to be getting more precipitation in general.”

And warmer temperatures will increase the likelihood of that precipiation being rain instead of snow. With the ground frozen, ice blocking storm drains, and without transpiration from trees and plants, significant increases in stormwater runoff could overwhelm existing infrastructure, resulting in greater flood risk.

“Right now most flood-related management strategies are based on previous experience of floods,” Liebl said. “Our concern is if flood peaks are getting considerably higher, we’ll never be in a position to manage floodwater because it will always be a little more flooding than expected.”

Challenge for Infrastructure

Liebl said urban storm drains were typically designed to handle so-called “10-year” rain events over 24 hours, or the amount of rainfall with a 10-percent chance in any year. Streets carry any volume above that. But in Wisconsin, Liebl said those “normal” volumes were calculated based on mid-20th-century rainfall data from a historically dry period. Add to that the “very gradual, long-term” increase in precipitation overall—plus the increase in the amount of precipitation during storms and incrementally larger surface flows—and actual 10-year rain events will be incrementally larger in volume, meaning that much existing infrastructure is not currently adequate to convey all that stormwater.

Liebl’s group is not suggesting a total revamp of existing sewer systems, but he said new infrastructure should follow updated data trends. The National Oceanic and Atmospheric Association is due to recalculate rainfall data for Wisconsin in 2011, incorporating the storms of the past few years, Liebl said, which should help infrastructure designers gain a more accurate picture of how much precipitation is possible.

“It’s important to realize that the design standards are used—they’re not arbitrary—but they don’t take into effect the size of rainfall that could occur,” Liebl said. Even so, he said the costs and benefits have to be weighed. “No matter how much we increase the capacity of our infrastructure there will always be more rain.”

Recommendations & Outlook

WICCI’s next task is educating the public and stakeholders about the risks and management options to deal with a changing climate that has already lengthened growing seasons and altered bird migrations in Wisconsin.

Liebl hopes that increased awareness will encourage land-use more sensitive to stormwater management, for individuals and across communities. “It’s interesting that in Wisconsin we’ve got regulation in stormwater quality but almost nothing about stormwater quantity,” Liebl said.

He doesn’t believe a large regulating authority is the answer, and said that communities’ self-interest should motivate them. Planning low-impact development and reducing impervious surfaces are two ways to be smart about stormwater. In already-built environments like the city, anything that promotes on-site infiltration—rain gardens, rain barrels, porous pavement, green roofs, and bioretention swales—can help reduce stormwater runoff.

Liebl compared stormwater management to Wisconsin’s snow shoveling ethic. “Everybody knows snowfall is something you have to deal with,” Liebl said. “Rainfall has a way of going downhill, out of sight, out of mind.”

But he said people need to remember that stormwater has consequences downstream, even if not always as dramatic as an SUV sputtering in a sinkhole.

Rain Gauge Data

At the end of 2009 there were approximately 240 weather stations submitting precipitation data to the state’s official climate network, according to assistant state climatologist Ed Hopkins of the Wisconsin State Climatology Office, part of UW-Madison’s Atmospheric and Oceanic Sciences Department.

Another 65 citizen monitoring stations in Wisconsin participated in CoCoRaHS, the Community Collaboration Rain, Hail & Snow network that is now nationwide and reports data at cocorahs.org.

Hopkins said there’s definitely a need to modernize the state’s rain gauge data network but that the effort will boil down to money and commitment.

A Need for Better Data

Better data can help scientists refine their climate models and make better recommendations about how to manage stormwater.

Scientists are already using weather radar to actually measure the amount of rainfall from storms, Liebl said, which should provide more precise precipitation data as well as better alert people about flood potential.

Continuous hydrologic modeling would be a useful tool to better understand stormwater risks, Liebl said, but the state will need more rain and stream gauges to collect quality real-time data. “Right now people are probably not aware of how few rain gauges we have in Wisconsin,” Liebl said. The same goes for stream gauges, he said. “We don’t have as many as we need to be as accurate as possible.”

Over the next five to 10 years, Liebl also expects much more robust climate models as climate scientists develop new analytical methods.

Greendale’s Bioretention Swales

In 2009, when planning a Municipal Street Improvement Project along Grange Avenue between 60th and 68th streets, the Village of Greendale added median bioretention swales with wild flowers, mulch, and engineered soils that serve to remove silt and pollutants from stormwater runoff before it flows into Dale Creek.

Carl Tisonik, Greendale director of public works, said the project has exceeded expectations. The project was budgeted at $220,000, Tisonik said, and the state provided 80 percent of the funding; the village 20 percent.

Tisonik credits Greendale engineer Len Roecker with the idea and MMSD for PR support. Tisonik said he’s gotten calls from as far as Florida and Nevada asking about the project.

Trees Help Manage Stormwater

One of the recommendations for managing stormwater is to increase tree cover. “For every 5 percent of tree cover added to a community, stormwater is reduced by approximately 2 percent,” according to a presentation, “Trees and Their Role in Storm Water Management,” by Mindy Habecker at the Dane County UW-Extension.

In 2009, the city of Milwaukee’s estimated tree cover was 21.5 percent, according Forestry Services Manager David Sivyer, up from 16.5 percent in 1998. In the 3,732-acre 14th Aldermanic District, tree cover is 20 percent (Forestry’s goal is 30 percent) and grass cover is 26 percent, according to Sivyer.

Forestry has been more focused on “Emerald Ash Borer readiness” and has not moved forward with any private tree-planting initiatives, Sivyer said. However, in spite of the economy, Forestry’s funding for street tree replacement is holding steady, Sivyer said, and they’ve added over 2,400 shade trees to boulevards over the past couple years.

A CITYgreen spatial analysis of Milwaukee’s urban tree canopy estimated the stormwater benefit at $15 million, according to Sivyer, but this study did not project increased stormwater reduction benefits associated with increasing canopy.

Milwaukee Bioswales

In an effort to increase stormwater quality, the city of Milwaukee has installed approximately 20 bioswales on N. 92nd Street from Capitol Drive to Good Hope Road and about 10 on Grange Avenue from 26th Street east to the freeway, according to Scott Baran, with DPW’s Environmental Services.

Both projects are helping Milwaukee attempt to reach its goal of reducing the city’s total suspended solids loading. DNR has mandated that the city attempt to reach a 40-percent reduction in TSS by 2013, which Baran termed “a very ambitious goal.”

More bioswale projects are anticipated for S. Bay St. in 2011, and a project along S. Sixth Street from Howard to Layton is under consideration.

“These bioswales have been well received so far and also help with beautifying the boulevards,” Baran said, and have included the addition of 100 new street trees.

Stream Gauge Data

In Wisconsin, the U.S. Geological Service maintains 230 stream gauges, according to Rob Waschbusch, USGS hydrologist. It costs about $12,500 per stream gauge plus $11,500 to run each gauge annually, Waschbusch said. USGS can contribute 30 percent of new gauge costs if it gets a 70 percent local match.

WICCI is a partnership between the Wisconsin Department of Natural Resources and the University of Wisconsin-Madison. It was developed in 2007 after a bipartisan committee of state legislators wanted to know how climate change would affect their constituents and districts. Focus on Energy funded the climate research, supported by UW-Madison and DNR. A report synthesizing the predictions and recommendations of the WICCI working groups is expected by early 2011. More info: wicci.wisc.edu.

Source for all images: David Liebl’s Sept. 14, 2010 WICCI presentation, “Projected Climate Impacts and Adaptation Strategies for Wisconsin’s Urban Areas.”

Aggressive red swamp crayfish invades Wisconsin

October 1, 2010

By Craig Helker


The DNR responded to the threat of invasive red swamp crayfish in a five-acre Germantown lake surrounded by 84 residential properties by applying 500 gallons of bleach. So far, the DNR has spent over $100,000 in its effort to eradicate the invader. ~photo Brooke Robinson

In the early morning of Nov. 12, 2009, a tanker truck full of bleach pulled up to a small residential pond in the Germantown subdivision of Esquire Estates. The bleach was transferred to waiting boats, crewed by teams of biologists and technicians from the Wisconsin Department of Natural Resources. As the boats circled, pumping in 500 gallons of bleach, the water took on a blue appearance. Fish and tadpoles floated to the surface. And at the water’s edge, multitudes of red swamp crayfish, the target of all this effort, began to die.

Two and a half months earlier, a resident of Esquire Estates had contacted Heidi Bunk, DNR’s regional aquatic invasive species coordinator, to report strange “lobsters” in the pond behind his home. Bunk, who’d recently responded to an intentional release of a highly invasive aquatic plant called yellow floating heart in Walworth County, visited the Germantown pond and collected specimens of an unusually large and dark red crayfish. Joan Jass of the Milwaukee Public Museum subsequently identified them as Procambarus clarkii, the red swamp crayfish.


A Germantown resident reported strange “lobsters” to the DNR in 2009. The “lobsters” were actually invasive red swamp crayfish. ~photo Brooke Robinson

Red swamp crayfish are native to the Gulf Coast, but have since expanded their range to 15 states and over 25 countries, including Spain, Kenya, and Japan. Dark red, growing as big as a man’s hand, and very aggressive, the red swamp crayfish flourishes wherever it has been introduced. Worldwide, it is considered a commercial species, typically cultivated as a source of food.

It is also highly invasive. An ecologically plastic species, red swamp crayfish can adapt to a multitude of habitats and subsist on a variety of food sources, from aquatic plants to snails, detritus, fish, and amphibians. Individuals can survive long dry spells, and are known to migrate up to three kilometers in search of habitat. They’re also excellent reproducers, brooding twice a year, with females laying up to 600 eggs at a time.

It’s not known for sure how the red swamp crayfish was introduced to Wisconsin. But these crayfish are commonly utilized by schools for dissection and display, and it’s suspected that some may have been sent home with students as “pets,” then released. Or, it’s possible that someone ordered up a live shipment of red swamp crayfish for a crayfish boil, and then released a few.

Regardless of how they were introduced, they pose a threat to the aquatic ecology of Wisconsin. Studies have shown that aggressive red swamp crayfish outcompete smaller native crayfish species for resources and habitat. And, as carriers of the crayfish fungus plague, they can infect native crayfish with this muscle-damaging disease, further reducing native population numbers. Red swamp crayfish are also known to weaken stream banks through extensive burrowing, leading to excessive erosion and stream sedimentation.

In the late fall of 2009, as the smell of bleach dissipated from the air around Esquire Estates, DNR and students from UW-Madison conducted intensive follow-up trapping. It was hoped that the treatment had been successful, because a new population of red swamp crayfish had been reported at Poerio Park Pond in Kenosha, just 200 feet from a tributary to the Pike River, which flows directly into Lake Michigan. The follow-up trapping at Germantown found no live crayfish.

In 2010, however, once ice was off the Germantown pond, trapping started again. Live juvenile and adult red swamp crayfish were found almost immediately.

Sue Beyler, DNR inland fisheries supervisor and member of the red swamp crayfish response team, was disappointed but not really surprised.

“The Achilles’ heel to these treatments is when they’re in their burrows,” Beyler explained. “They burrow in such a complex manner, not only going back and left and right, but also up and down.”

Crayfish are natural burrowers, with some red swamp crayfish burrows documented to penetrate more than six feet into shore banks. Though known burrows were treated with bleach at the Germantown pond, it’s thought that the surviving red swamp crayfish had been well protected in their deep burrows.

In response to the failure of the bleach treatment, DNR tried a new approach. Over the last week of August 2010, the pond at Poerio Park in Kenosha was drained as far as possible and the exposed shoreline treated with a pyrethroid insecticide. First derived from the chrysanthemum flower, pyrethroids affect the nervous system of invertebrates. To date, however, the treatments appear to have had no long-term effect on red swamp crayfish populations at Poerio Park.

So, it’s back to the drawing board for DNR as they investigate other control options. If there is a bright side to this ongoing and intensive fight against Wisconsin’s newest aquatic invasive species, one that Beyler reports has cost over $100,000 to date, it’s that these are localized outbreaks. “DNR has responded to many purported sightings, but so far, red swamp crayfish have not been found outside of these two locations,” Beyler said.

Stop the Spread of Aquatic Invasive Species

NEVER release any aquarium pets into the wild.
INSPECT boat, trailers, and equipment and REMOVE plants, animals, and mud.
DRAIN water from your boat, motor, bilge, live wells, and bait containers.
DON’T MOVE live fish away from a water body.
DISPOSE of unwanted bait in the trash.
RINSE boat and equipment with hot or high pressure water OR dry for at least 5 days.

Craig Helker is a water resources biologist with the Wisconsin Department of Natural Resources and conducted red swamp crayfish burrow treatments at the Germantown pond.

Researchers link rain and illness

August 30, 2010

By Jennifer Yauck

Campylobacter Giardia Norovirus Bacteria like Campylobacter (left), viruses like Norovirus (middle), and protozoa like Giardia (right) are among the tiny disease-causing organisms that can be spread through water. ~photos courtesy CDC / Patricia Fields & Collette Fitzgerald / Charles D. Humphrey / Stan Erlandsen

Outbreaks of waterborne diseases in the United States and other parts of the world are often linked to water contamination following heavy rainfall. But evidence from a recent study conducted in Milwaukee suggests that unrecognized waterborne diseases may be occurring in association with less severe rainfall, too—even in areas served by high-quality drinking water systems.

Nationwide, more than 100 outbreaks of waterborne diseases—like diarrhea-causing cryptosporidosis or giardiasis—were reported to the U.S. Centers for Disease Control and Prevention between 2005 and 2006, the most recent years for which data have been tallied. But outbreaks that are notable enough to be reported to health authorities are “just the tip of the iceberg,” said physician Marc Gorelick, chief of pediatric emergency medicine at the Medical College of Wisconsin (MCW) and the study’s lead researcher. “It takes a huge increase [in the number of people getting ill] for someone to notice something.”

To test if additional waterborne diseases might be slipping under the radar, Gorelick and other researchers from MCW and UW-Milwaukee (UWM) compared data on the number of daily visits made by children to the Children’s Hospital of Wisconsin emergency department for diarrhea or gastroenteritis between 2002 and 2007 with daily rainfall data for the same period.

They found that four days after rainfall of any amount, the average number of visits per day (8.1 visits) was 11 percent higher than it was four days after no rain (7.3 visits). The study cannot prove that rainfall-induced water contamination necessarily caused the observed illnesses, Gorelick said, but the spike in visits after rain certainly hints at that possibility.

Searching for Pathways

So next, Gorelick and his fellow researchers plan to investigate specific ways in which run-of-the-mill rain might be leading to water contamination, and how people might be getting exposed to that contamination.

They already have some theories. Bacteria, viruses, and protozoa are the usual culprits of waterborne disease, and their numbers in rivers and other surface waters often increase after rain—even when there aren’t sewer overflows. That suggests the disease-causing bugs are entering our waterways from land, most likely from runoff or old, leaky sewer pipes, Gorelick said.

People may be getting exposed to those bugs when they swim or play in the contaminated water, or eat or drink after touching the water, said study collaborator Sandra McLellan, a senior scientist at UWM’s Great Lakes WATER Institute. Often, exposed people won’t experience symptoms until days later—as was seen in the researchers’ study—because many types of disease-causing organisms incubate in a person’s body for several days first.

People can reduce the risk of becoming sick from contaminated environmental waters by practicing good hygiene, such as hand washing, after being in contact with it, McLellan said.

And what about drinking water? Although there have been instances locally and around the country where disease-causing organisms have been transmitted to people through drinking water, McLellan said the water leaving Milwaukee’s treatment plant is of very high quality. Gorelick agreed. “They do outstanding water treatment,” he said.

But, Gorelick said, “what we don’t know is what happens to water between the time it leaves the treatment plant and gets to your tap.” In some areas where pipes are old and leaky, wastewater from sewage pipes could make its way through saturated soil into drinking water pipes. This probably doesn’t happen regularly because drinking water pipes are normally under pressure, he added, but it could be an issue in situations where pressure is lost—for instance, due to a water main break.

“The take-home message is we have potential problems related to our infrastructure that we need to be aware of, but in general our drinking water is really quite safe,” Gorelick said.

Aging Pipes, Climate Change

Along with aging infrastructure—Gorelick pointed out that some area water pipes have been around for 100 years—climate change could potentially exacerbate the problem of waterborne disease in the future. Warmer air can hold more moisture, and climate experts predict that will lead to more frequent and more intense precipitation.

“Urban areas really can’t handle Mother Nature when we have extreme rainfall,” McLellan said. “So we have to have foresight in how we build our cities to handle stormwater and wastewater in the future.”

“As our infrastructure gets even older and we see changes in precipitation, [waterborne disease] will become a bigger problem,” Gorelick said. “We shouldn’t get complacent.”

Jennifer Yauck is a science writer at UWM’s School of Freshwater Sciences (freshwater.uwm.edu) and Great Lakes WATER Institute (glwi.uwm.edu), the largest academic freshwater research facility on the Great Lakes.

A brief prehistory of Lake Michigan

July 30, 2010

By Patricia Coorough Burke, Karen Morgan, Joshua Pierce, and Michael Timm

The story of Lake Michigan starts over a billion years ago—before the first dinosaurs were even a twinkle in their parents’ eyes. During this primordial period in our planet’s history, the precursor to the North American continent was literally being pulled apart.

A rift had developed in the middle of the North American plate, with magma pushing up from Earth’s mantle and threatening to split the plate in two.

Called the Midcontinent or Keweenawan Rift, it was similar to the modern-day East African Rift where the African Plate is being split into two new plates by upwelling magma—the plates are stretched and broken by faults that allow the magma to reach the surface, forming volcanoes like Mt. Kilimanjaro.

Some 1.1 billion years ago, lava seeped out of the Keweenawan Rift and forced the continent itself apart like a forceps. Although the spreading ultimately halted and the plate remained intact, the rift remained. A weak spot, a sort of planetary hernia, had developed. The sheer weight of the volcanic layers that had oozed out and solidified into rock above began to depress the crust, creating a preliminary basin. This natural low spot started to collect water.

Silurian reef

The Silurian reef, as represented at the Milwaukee Public Museum in its popular Third Planet exhibit. Sea creatures like the cephalopods and trilobites shown inhabited the area that is now the Midwest approximately 400 to 440 million years before the present. When they died, their shells settled to the bottom of the shallow sea and over time were compressed into the dolomite that underlies Lake Michigan today. ~courtesy Milwaukee Public Museum

The Shallow Seas

Over the next several hundred million years North America was repeatedly flooded as the prevailing climate fluctuated. The shallow, salty seas over what is today the Great Lakes region hosted a variety of life including coral and mollusks but also forms alien to us today—like the squidlike cephalopod and what’s become Wisconsin’s state fossil, the trilobite.

When these hard-shelled creatures died and settled to the then-seafloor, the calcium in their hard parts formed rocks—mainly limestone, composed of calcium carbonate (calcite), and dolostone, composed of calcium/magnesium carbonate (dolomite). Over time, layers and layers of dead creatures and sediment were compressed into sedimentary rocks. The base of Lake Michigan today is actually a layer of dolomite formed between 440 and 417 million years ago, during the Silurian Period.

Prehistorically, water drained from the preliminary basin at the continent’s interior along much the same routes as it does today—north toward present-day Hudson Bay and east toward the present-day Gulf of St. Lawrence. Millions of years before the glaciers, river systems excavated valleys and canyons through layers of sandstone, limestone, and shale on their way. Like varicose veins soon to become swollen beyond their fractal channels, the course of these prehistoric rivers would determine the future footprint of the Great Lakes.

Great Lakes Atlas Page

Glacial Transformation

Compared to the time it took the sagging basin of rock beneath them to develop, the Great Lakes themselves formed in just the blink of an eye of geologic time.

Just more than one million years ago, during a planetary ice age when ice covered an estimated 30 percent of the Earth’s land area, a glacial ice sheet descended on the region from the north. The glacier’s scouring power deepened and enlarged river valleys in the basin, scraping the softer surface rocks from the harder bedrock below.

Glaciers “advanced” when their leading edges accumulated more ice and “retreated” when existing ice melted. When enough ice accumulated, the massive bodies actually flowed like slow rivers of molasses, exerting tremendous amounts of force onto and across the land like a giant plow—powered by the weight of sometimes more than a mile-high mountain of ice. Like rivers, the glaciers slogged through lowlands, scouring them lower, depositing huge rock debris piles, or moraines, that marked their farthest advances.

This melt-and-freeze cycle of glaciation repeated for thousands of years. Interestingly, the size of glaciers in the pre-Great Lakes region may have been enhanced from prehistoric “lake effect” snows, which piled up dozens of feet of new snow directly in the area, too fast for it to melt.

Not only did glaciers sculpt the actual shapes of the Great Lakes’ basins, but their massive presence also altered where water collected and how it drained throughout the region by damming previous drainage ways.

The glaciers melted and retreated from the area during a natural global warming phase, and by approximately 10,000 years ago they had retreated permanently to the north. Once the ice was gone, all that weight was no longer pressing down on the earth—the underlying bedrock began to rebound like a trampoline bouncing back after you jump on it. This “isostatic rebounding” continues today, with areas of Lake Michigan rebounding between 30 and 50 centimeters per century, as estimated using Global Positioning System satellite data.

For the last few thousand years, the shape and depth of the newly carved lake basins changed, even as melted glacial ice slowly filled them.

It’s thought that what’s now Lake Michigan, for example, went through many iterations—as Lake Chicago (a blobby lake smaller in surface area near Chicago and cut off to the north by glaciers), Lake Algonquin (when Lakes Michigan and Huron were deeper and connected due to glacial damming), Lake Chippewa (an emaciated-seeming narrower version of Michigan), Lake Nipissing (a superlake connecting Michigan even more to Superior and Huron), and finally the familiar drooping shape we instantly recognize as Lake Michigan today.

And even that’s not a constant. From a geological perspective, Lake Michigan is but a transitory form—a two-bit actor in the ongoing drama of the planet’s much larger rock and water cycles.

Patricia Coorough Burke, Karen Morgan, Joshua Pierce, and Michael Timm contributed to this report.

Explore More
— about the Great Lakes’ formation: www.on.ec.gc.ca/greatlakeskids/greatlakesmovie5.html.
— about Wisconsin geology: uwex.edu/wgnhs

What’s in your wetland?

June 2, 2010

By Jennifer Yauck


Reed canary grass. ~courtesy UW-Stevens Point and Christopher Noll

Prior to the 1800s, Wisconsin contained nearly 10 million acres of wetlands. In fact, Milwaukee, which lies at the mouth of three converging rivers, was itself originally a marsh. The marsh covered portions of present-day downtown, the Menomonee Valley, the Third Ward, Jones Island, Walker’s Point, and Bay View, according to historian John Gurda in The Making of Milwaukee.

But over the last two centuries, nearly half of Wisconsin’s wetlands-Milwaukee’s marsh included-have been drained and filled to create space for cities and agriculture.

Such wetland losses have slowed in the last several decades due to regulations and an increased appreciation of the role wetlands play in preventing flooding and improving water quality. “Wetlands used to be the place where you dumped your old refrigerator, but now they’re gems,” said Joy Zedler, a UW-Madison botanist who studies wetland plants. Still, Wisconsin’s remaining wetlands face other threats today. Near the top of the list are invasive plants.


Hybrid cattail ~courtesy Wisconsin State Herbarium and Robert W. Freckmann

Beetle Battle

In their natural state, wetlands support a rich diversity of plants that provide food and habitat for more animal species than any other type of Wisconsin landscape. But when an invasive plant moves in, there’s little to keep its growth and spread in check and so it can quickly crowd out native plants. The resulting invasive-dominated wetlands are less stable than diverse wetlands, and provide little food for native animals, said Wisconsin Department of Natural Resources (DNR) ecologist Brock Woods.

Woods coordinates control projects for invasive purple loosestrife, a Eurasian plant that was brought to the East Coast in the 1800s for ornamental use. Now found throughout Wisconsin as well as around the country, the prolific plant spreads via cut roots and stems and through the millions of sand-grain-sized seeds it produces each year.

Woods and other managers around the country have succeeded in stifling the plant’s growth and spread in many places by introducing special purple loosestrife-eating beetles. Though themselves non-native, the beetles live exclusively on purple loosestrife and are not a threat to other plants, according to the DNR.

But Woods cautioned that the purple loosestrife battle doesn’t end with the beetle. As a plant infestation is brought under control-a process that can take years-the newly opened wetland space must be “filled with what we want so it doesn’t get filled with what we don’t want,” said Woods. “You won’t get native insects and animals back until you get the wanted vegetation back.”

Difficult to Control


Purple loosestrife ~courtesy Wisconsin State Herbarium and Robert Bierman

Other major invasive plants in Wisconsin include reed canary grass and hybrid cattails. Reed canary grass is a Eurasian native and one of Wisconsin’s oldest and most common wetland invaders. In the past, people intentionally planted this grass to control stream bank erosion because it grows quickly and densely, said U.S. Army Corps of Engineers ecologist Brook Herman. Those very qualities now make reed canary grass difficult to control.

Hybrid cattails, a cross between a native wide-leaved cattail and a non-native narrow-leaved cattail, also pose a challenge. They tolerate a broad range of water levels and are very aggressive, crowding out native species above ground with their dense stands and below ground with a network of wiry stems and roots, Zedler said.

“Biocontrols” such as beetles are not available for reed canary grass or cattails. Instead, attempts to manage them usually rely on the use of herbicides or mechanical means such as mowing or burning.

For the most part, though, these and other invasive plants that are already established in Wisconsin “are here to stay,” Woods said. “The only ones we have a good chance of getting rid of are the ones that are just starting to show up.”


Purple loosestrife-eating beetles like this one are helping the DNR control the invasive plant. The public can help the DNR rear the beetles. ~courtesy Bernd Blossey

Towering Grass

One such plant is the common reed, often referred to by its scientific name, Phragmites (pronounced frag-MY-tees). A grass that can tower up to 12 feet tall, non-native Phragmites is well established along Lake Michigan in northeastern Wisconsin, Woods said, but has just begun invading further inland. It tends to spread along highway ditches because, unlike many other plants, it tolerates road salt well.

“People need to learn to identify and control it while distinguishing it from native Phragmites,” Woods said. “It’s early enough that there’s still hope of keeping it out of most of the state.”

Woods and Zedler said the public can and should play a role in fighting invasive plants. “These are marvelous opportunities for neighborhoods,” said Zedler. “They can find out if their local wetlands have invasives, they can get to know what’s out there.” Woods said individuals and school and community groups can help the DNR raise purple loosestrife-eating beetles. “They’re fun to rear. Anyone who wants a project that’s part of the solution can do it,” he said.

“Each of us has to become knowledgeable…and demand tools [for dealing with invasives] that will be successful,” Woods said. “The quality of where we live is up to us.”

Jennifer Yauck is a science writer at the Great Lakes WATER Institute. GLWI (glwi.uwm.edu) is the largest academic freshwater research facility on the Great Lakes.

More About Wetlands and Invasives

  • Wetland Gems – Learn about 100 notable wetlands in your area and around the state by visiting the Wisconsin Wetland Association website at wisconsinwetlands.org/gemslist.htm.
  • Beetle rearing – Get involved in rearing purple loosestrife eating-beetles by contacting the DNR’s Brock Woods at brock.woods@wisconsin.gov or (608) 221-6349.
  • Invasive roll call – Find more information about Wisconsin’s invasive plants at dnr.wi.gov/invasives/plants.asp and ipaw.org/information.aspx.

Non-native Phragmites ~courtesy DNR


Close-up of Reed canary grass ~courtesy UW-Stevens Point and Christopher Noll

Aquatic invaders come in small packages, too

May 1, 2010

By Jennifer Yauck

Graduate student Paul Engevold rinses down a sampling net to capture waterfleas and other plankton from Lake Michigan in a collection cup. ~photo John Karl, Wisconsin Sea Grant

Graduate student Paul Engevold rinses down a sampling net to capture waterfleas and other plankton from Lake Michigan in a collection cup. ~photo John Karl, Wisconsin Sea Grant

Of the roughly 200 non-native animal and plant species that have established themselves in the Great Lakes since the 1800s, the ones that most grab our attention are often relatively large. There’s the sea lamprey. The alewife. The zebra mussel and quagga mussel. And now-not yet established, but knocking on Lake Michigan’s door-the really large Asian carp.

But small, less visible non-native species also invade the Great Lakes. And, despite their size, some have the potential to impact the lakes’ ecosystems in a big way.

UW-Milwaukee (UWM) researchers have been studying two such tiny invaders-zooplankton known as the spiny waterflea and the fishhook waterflea-to better understand their effects on Lake Michigan’s food web. Named for their barbed and hooked tails, respectively, adult spiny and fishhook waterfleas measure between just a quarter-inch and half-inch long, with their thin tails accounting for most of that length.

The two invaders are native to seas near the Europe-Asia border and were likely transported to the Great Lakes in the ballast water of ships. The spiny waterflea was first spotted in Lake Michigan in the late 1980s; the fishhook waterflea in the late 1990s. Both are found in all of the Great Lakes to varying degrees, and the spiny waterflea is also found in some inland waters. They are especially abundant in Lake Erie, where they cause trouble for fishermen by collecting on lines and nets in gelatinous globs.

Carnivorous Invaders

“One reason we’re interested in them is because they’re big-time carnivores,” said John Berges, associate professor in UWM’s Biological Sciences Department. Berges is collaborating with project leader Craig Sandgren, associate professor and chair of the department, on the research.

In particular, the waterfleas eat other tiny zooplankton-and that can have an impact up the food web by reducing the amount of food available for young, zooplankton-eating fish. Adding insult to injury, the waterfleas themselves don’t make good meals for young fish because their tails make them hard to digest. “It’s like the nice, grassy pasture was replaced with bramble,” Berges said.

This fishing line is covered with a mass of spiny waterfleas. ~photo Jeff Gunderson, Minnesota Sea Grant

This fishing line is covered with a mass of spiny waterfleas. ~photo Jeff Gunderson, Minnesota Sea Grant

The waterfleas’ diets also can have an impact down the food web. If the waterfleas feed heavily on herbivorous zooplankton-those that feed on phytoplankton, or tiny algae-the algae can grow unchecked, and nuisance algal blooms can result.

And although both waterfleas occupy spots in the middle of the food web, they may actually “cooperate” with one another-by favoring different types of zooplankton prey, for example-rather than compete, thereby amplifying their impact, Berges said.

Who’s Eating Whom?

To get a more detailed picture of how the invasive waterfleas are affecting Lake Michigan’s food web, Berges and Sandgren are comparing the current and historical compositions of the food web, and working to identify “who eats whom,” Berges said.

But determining exactly “whom” waterfleas eat isn’t simple. “Ideally, you’d like to become the Jane Goodall of waterfleas and watch what they do [in their environment], but that’s not possible,” Berges said. Neither is examining their gut contents for visually identifiable prey, because the waterfleas feed like vampires, sucking out their prey’s bodily fluids.

So instead the researchers collect samples of plankton-filled water from the lake and put them in incubators in the lab under simulated natural light and temperature conditions. After counting the various organisms in the samples, they wait to see “who disappears,” Berges said. So far, they’ve found the waterfleas are “pretty ravenous,” and able to eat most other zooplankton species they encounter. “This tells us what they are capable of, but it doesn’t necessarily tell us what they can do in a natural ecosystem,” cautioned Berges.

So the researchers are also taking an immunochemical approach, developing antibodies that are specific to several of the waterfleas’ probable prey species. The antibodies will allow the researchers to detect those species’ bodily fluids if they are among the waterfleas’ gut contents. They’ve currently developed antibodies for 12 prey species, and will test them later this year.

Thus far, the researchers’ field investigations reveal a marked decline in some of Lake Michigan’s native zooplankton. But Berges said it isn’t clear yet if the invasive waterfleas are the sole culprits. “Changes in climate and nutrient cycling in the lake may also be factors, and their effects are much harder to tease out,” he said.

The fishhook waterflea (top) has an angled tail with a distinctive hook at the end, while the spiny waterflea (bottom) has a straight, barbed tail. These two aquatic invaders are native to seas near the Europe-Asia border and were likely transported to the Great Lakes in the ballast water of ships. ~courtesy NOAA Great Lakes Environmental Research Laboratory

The fishhook waterflea (top) has an angled tail with a distinctive hook at the end, while the spiny waterflea (bottom) has a straight, barbed tail. These two aquatic invaders are native to seas near the Europe-Asia border and were likely transported to the Great Lakes in the ballast water of ships. ~courtesy NOAA Great Lakes Environmental Research Laboratory

Berges said that although there are reasons to be concerned about the waterfleas, they haven’t yet taken over Lake Michigan to the extent they have elsewhere, like Lake Erie. That in itself is interesting, he said, and the researchers would like to figure out why it’s the case. “It would help us understand the factors that might help control them, in order to limit invasions in other lakes or to counteract the current invasion.”

Jennifer Yauck is a science writer at the Great Lakes WATER Institute. GLWI (glwi.uwm.edu) is the largest academic freshwater research facility on the Great Lakes.

Stopping aquatic hitchhikers

The spiny and fishhook waterfleas can spread to inland waters via boats and fishing gear. Females can reproduce without mating, so only one individual is needed to infest a body of water.

To help stop the spread of invasive waterfleas, do the following before leaving a boat launch site:

  • REMOVE plants, animals, and mud from your boat, trailers, and equipment
  • DRAIN water from your boat, motor, bilge, live wells, and bait containers
  • DISPOSE of unwanted bait in the trash
  • Report new sightings of waterfleas in inland waters to your local Wisconsin Department of Natural Resources office.

Sources: The Wisconsin and Indiana Departments of Natural Resources and Minnesota Sea Grant.

Land, lakes linked underground by sinkholes

April 1, 2010

By Jennifer Yauck

Robert Ballard, discoverer of the sunken Titanic, and a team of researchers set out in 2001 to map shipwrecks offshore of Michigan in Lake Huron’s Thunder Bay National Marine Sanctuary. A geologist by training, Ballard took notice when imagery from the team’s side-scan sonar revealed dozens of large depressions in the lakebed.

Upon further inspection, the depressions proved to be sinkholes. Researchers were surprised to find some of them teeming with brilliant purple bacteria and other peculiar, seemingly primitive organisms (see March Bay View Compass). Similar life forms previously had been found only in extreme places like the deep sea and Antarctica.

So how is it that humble Lake Huron came to harbor these unusual oases?  »Read more

Lake Huron sinkholes harbor unexpected life forms

March 1, 2010

By Jennifer Yauck


Located 75 feet below the surface of Lake Huron, Middle Island Sinkhole is visible from the sky in this photo. The shoreline of Middle Island and a boat on the right provide a sense of scale. ~courtesy Grand Valley State University

Compared to the dark depths of the ocean or the frigid ends of the earth, Lake Huron hardly seems like an extreme environment. But sinkholes discovered at the lake’s bottom have conditions just as harsh-and harbor life forms just as unusual-as those of deep-sea hydrothermal vents or Antarctica’s permanently frozen lakes.

And like their marine and polar cousins, the sinkholes’ peculiar occupants-mostly microbes-are providing scientists a glimpse of what early life on Earth might have looked like.

Located in the Thunder Bay National Marine Sanctuary area just off the index finger of Michigan’s “mitten,” the sinkholes are thought to have formed thousands of years ago, before the water now known as Lake Huron covered the area. The sinkholes formed in spots where flowing groundwater dissolved layers of gypsum underground, creating cavities into which the overlying rock collapsed. Today, groundwater still moves through the system, dissolving minerals out of the rock and flushing them up into Lake Huron through the sinkholes.

An Extreme Environment

Researchers first stumbled upon some of the sinkholes in 2001 while surveying the Thunder Bay area for shipwrecks. Subsequent explorations of Isolated Sinkhole, located about 10 miles off shore in more than 300 feet of water, revealed that the groundwater seeping out the lake-bottom fissure was very different from the lake water. The groundwater lacked oxygen and had a chloride concentration 10 times higher and a sulfate concentration 100 times higher than that of the lake.


Purple mats of thread-like cyanobacteria carpet the floor in this ROV image from Middle Island Sinkhole. The mat’s fingerlike projections are formed by methane gas released from the underlying sediment. ~courtesy Great Lakes WATER Institute

That got Bopaiah Biddanda, an ecologist at Grand Valley State University in Muskegon, Mich., thinking. “If water with different chemistry is coming out,” he said, reflecting back on his thoughts at the time, “maybe there are different kinds of life there.”

So in 2003, he and his colleagues set out with divers and a remotely operated vehicle, or ROV, outfitted with a video camera and other equipment to take a look. “We had no clue what we would find,” he said.

Biddanda ranks what they did find-vibrant ecosystems of microbes that thrive in conditions too extreme for most modern life forms-as one of the “most exciting” discoveries of his career. Previously, such “extremophiles” had been documented only in places like deep-sea hydrothermal vents and frozen Antarctic lakes. “We found something that wasn’t thought to exist in the Great Lakes,” he said.

The microbes flourish in the sinkholes’ harsh chemical conditions-the water is sulfur-rich and oxygen-free-because they use hydrogen sulfide (the “rotten egg” gas) rather than hydrogen oxide (water) for their metabolic processes. That makes them similar to primitive life forms thought to inhabit Earth some two to three billion years ago, before oxygen was abundant.

A Spectrum of Microbes

The types of microbes the researchers found in Lake Huron varied from sinkhole to sinkhole, depending on the availability of light. Situated in just three feet of water, the well-lit El Cajon Sinkhole is home to organisms such as green algae and cyanobacteria, which are photosynthetic and therefore need light. Located 100 times deeper, Isolated Sinkhole is almost completely dark, and populated by white mats of bacteria that carry out chemosynthesis instead of photosynthesis.


This map shows the location of several sinkholes in Lake Huron. The lake is represented by the colored area, which changes from red to blue with increasing depth. ~courtesy National Oceanic and Atmospheric Administration/Great Lakes Environmental Research Laboratory

Both photosynthetic and chemosynthetic microbes live at Middle Island Sinkhole, located at an in-between depth of 75 feet. Among Middle Island’s most fascinating occupants are thread-like cyanobacteria that cohere to each other to form brilliant purple mats. The mats are punctuated by fingerlike projections filled with methane gas released from the sediment below.

In their constant quest for light, the photosynthetic microbes making up the mats glide past one another or over obstructions, such as the particulate matter that settles out on them from the water above. “One day, I put pebbles on [a mat sample in the lab],” said Biddanda, “and by the next morning the mat had ‘climbed’ over them.”

According to a DNA analysis conducted by University of Wisconsin-Stout biologist Stephen Nold, the purple cyanobacteria’s closest known relative is a photosynthetic bacterium found on the bottom of an Antarctic lake.

Along with the assortment of microbes, researchers have occasionally-and surprisingly-found more complex life forms, like microscopic worms, living in the harsh sinkhole environments. “We don’t know how they are managing against the odds,” said Biddanda.

That’s just one of the many intriguing aspects of the sinkholes scientists are eager to explore. Researchers are currently working to answer a myriad of biological, chemical, and geological questions-from how old the sinkhole groundwater is, to how chemicals and nutrients cycle through the system, to whether compounds produced by the newly found microbes have medicinal value.

The work of unraveling the mysteries of Lake Huron’s sinkholes has just begun.

Jennifer Yauck is a science writer at the UWM Great Lakes WATER Institute. GLWI (glwi.uwm.edu) is the largest academic freshwater research facility on the Great Lakes.

CORRECTION (MAY 6, 2010): The original version of this article misstated the type of rock that is thought to have been dissolved by groundwater, thereby creating Lake Huron’s sinkholes. The rock primarily affected is gypsum, not limestone. Limestone, however, is one of the main rock types found in this area.

Explore some more!

Cruise along with an ROV as it explores Lake Huron’s sinkholes-visit miearth.org/play.php?vid=268.

Meet sinkhole researchers, read expedition logs, check out expedition videos and more by visiting NOAA’s Ocean Explorer page at oceanexplorer.noaa.gov/explorations/08thunderbay. Teachers, be sure to check out the page’s “Education” link (left side of page)-you’ll find sinkhole lesson plans for grades 5-12 and other useful resources.

Can Asian carp invasion be averted?

January 31, 2010

By Kathleen Schmitt Kline

flying fish option 2

Not only does the jumping silver carp pose a hazard for boaters on the Missouri River, but it and its non-jumping relative, the bighead carp, also pose an ecological hazard for native fishes. ~courtesy University of Missouri Cooperative Media Group

In December 2009, an environmental emergency brigade of 450 Americans and Canadians descended on Romeoville, Ill., armed with nets, boats, and thousands of gallons of poison. The urgent, 20-agency response was brought on by recent environmental DNA (eDNA) tests indicating that Asian carp were closer to invading Lake Michigan than previously thought. The tests detect traces of Asian carp DNA in water samples within a 48-hour period.

One of the 450 who dropped everything and headed to Romeoville was Phil Moy, a fisheries and aquatic invasive species specialist with the University of Wisconsin Sea Grant Institute. Fifteen years ago, Moy served as the first manager of a project to erect an electric barrier in the Chicago Sanitary and Ship Canal to repel foreign fish.

Chicago dug this canal more than a hundred years ago to manage wastewater, and its construction joined two major ecosystems that until then had remained isolated. Over the last several decades, Asian carp that escaped from Southern aquaculture and wastewater facilities have been moving up the Mississippi to the Illinois River, and the canal connecting it to Lake Michigan is an ideal pathway for the fish to advance into the Great Lakes.

In December, scheduled maintenance required temporarily shutting down part of the barrier. Because eDNA tests showed Asian carp advancing, a 5.7-mile section of the canal was treated with rotenone, a fish poison, to ensure that no carp would breach the barrier during the maintenance.

Moy was on hand-and often on a boat-during the seven-day effort that required coordinating all of the state and federal agencies involved using the Incident Command System, a procedure similar to that used to coordinate efforts to fight large wildfires in the West.

Moy has remained active on the electric barrier project as co-chair of its advisory panel. However, he admits that the barrier is only a temporary solution. Ultimately, he said, the only sure way to keep Asian carp and other invasive species out of the Great Lakes is to permanently sever the link between the Mississippi River and Great Lakes basins.

“I really think that’s the direction we have to go,” Moy said.

Final Chicago Waterways map

What Would Carp Need?

The four species of Asian carp-bighead, silver, black, and grass-pose a significant threat to the Great Lakes commercial and sport fisheries, collectively valued at more than $7 billion annually.

The filter-feeding fish can grow to be more than 100 pounds, and they are capable of daily gobbling up 20 percent of their weight in plankton, the tiny organisms that provide the foundation of the Great Lakes fishery food chain.

In addition, motor boat engine noise startles silver carp, causing them to shoot up in the air as high as 10 feet. Airborne silver carp have injured several boaters on the Mississippi and Illinois rivers-where Asian carp, imported from Taiwan in the 1970s to consume the waste in aquaculture and wastewater systems, have elbowed out native fish to become the dominant species in many areas.

Although there’s no question the carp pose a threat to Great Lakes fish and boaters, Moy said a successful Asian carp invasion is by no means a sure thing. “It takes some specific habitat for them to do really well,” he said.

Scientists estimate that the carp need access to a river with a deep, free-flowing main channel in order to successfully reproduce. If their eggs settle to the river bottom before hatching, the embryos will suffocate and die.

“One hundred kilometers-about 63 miles-is roughly the distance needed to provide enough current to keep the fish’s fertilized eggs suspended in water while they incubate,” Moy said. Out of thousands of tributaries that feed the Great Lakes, only 22 on the U.S. side (four in Wisconsin) meet this criterion. Adding another criterion-the availability of quiet, fertile backwater areas where the newly hatched fish larvae can eat and mature-reduces the list even more.


An empty barge passes through the Barrier reach, June 2005. ~photo Phil Moy

However, before they can reproduce, the fish would need to find each other within more than 94,000 square miles of the Great Lakes. While a few bighead carp have been captured in Lake Erie, probably due to someone releasing them there, they have yet to multiply into any significant numbers.

Indeed, Moy said it’s all about numbers now, and that’s why the electric barrier is still important.

“We have to keep the numbers as low as humanly possible,” he said. “Even if there are a few Asian carp upstream of the electrical barrier, there is absolutely no assurance that they’ll be able to establish a population.”

However, Moy said that the electrical barrier is not a permanent solution, because it depends on the fish reacting predictably to a technology that could potentially fail. In addition, it doesn’t do anything to protect the Mississippi River basin from small, floating invasive species coming from the Great Lakes, such as quagga mussel larvae.

“We really need to establish a two-way separation in order to really protect both basins,” he said.

Restoring the Natural Separation?

Accomplishing this would be challenging, but possible, Moy said, and shutting down the canal locks would only be one step.

The Des Plaines River runs parallel to the Sanitary and Ship Canal, and flooding in 2008 sent water from the Des Plaines overland into the canal upstream of the barrier. The Army Corps is now investigating how best to address this “leaky” spot.

Other potential leaks around the Great Lakes would likely need to be addressed, too. A mere two miles of marshy, flat terrain separates the Mississippi and Great Lakes basins at Portage, Wis., where a canal was dug in 1851 to connect the Wisconsin and Fox rivers. Asian carp have now advanced as far north as Lake Pepin in the Mississippi River, well upstream of its confluence with the Wisconsin River.

Moy and other biologists worry that Asian carp could drastically change the Great Lakes food chain, just as a string of other aquatic invasive species have caused sweeping changes over the last century.

In the 1800s, blood-sucking sea lamprey invaded the lakes through locks and shipping canals connecting the Great Lakes to the Atlantic Ocean. The lamprey’s introduction caused a major collapse of lake trout, whitefish, and chub populations during the 1940s and 1950s. The absence of large predator fish like lake trout caused an explosion in the population of small, silvery alewives, which were introduced to Lake Erie in the 1930s and soon spread throughout the Great Lakes. Then, to fill the gap left by lake trout, fisheries agencies introduced coho and Chinook salmon to control alewife numbers and provide an exciting sport fishing experience.

Canada and the United States spend approximately $18 million a year to control sea lamprey numbers using a toxin that specifically targets the lamprey. Moy said a similar effort might have to be launched for Asian carp if they successfully invade the Great Lakes, although a carp-specific toxin has not yet been developed.

Kathleen Schmitt Kline is a science writer at the University of Wisconsin Sea Grant Institute, which supports research, education, and outreach dedicated to the stewardship and sustainable use of the nation’s Great Lakes and ocean resources. Visit seagrant.wisc.edu for more on Asian carp, including video of the fish.

Asian Carp Facts

The common term “Asian carp” includes four types of carp native to Asia that have been introduced in the United States over the last three decades: bighead, silver, black, and grass.

Size: Commonly 24-30 inches and 3-10 pounds, but capable of growing to more than 50 pounds.

Preferred habitat: Large warm-water rivers and impoundments.

Threat: Asian carp are tremendous filter feeders that would likely out-compete many native fish if they become established in the Great Lakes. Silver carp jump out of the water in response to outboard motors and can seriously injure boaters.


Early 1970s Asian carp are imported from Taiwan to the United States for cleaning aquaculture ponds and sewage treatment facilities. Flooding allows them to escape into the Mississippi River basin.

1995 As Asian carp make their way up the Mississippi River to the Illinois River, an advisory panel forms to aid the U.S. Army Corps of Engineers in finding an environmentally sound method for preventing the spread of the carp and other aquatic nuisance species through the Chicago Sanitary and Ship Canal.

1997 Barrier Advisory Panel recommends an electric barrier as the best approach with the least number of drawbacks. However, the panel notes that no approach relying on animal behavior or a technological solution, as opposed to a physical separation, could be 100-percent effective in stopping the movement of aquatic invasive species through the canal.

April 2002 The Army Corps begins operating the first electrical barrier (Barrier I) as a demonstration of a new technology for preventing the spread of aquatic nuisance species. The barrier operates at a strength of one volt per inch, strong enough to repel most adult fish, but possibly not strong enough to repel smaller juvenile fish.

Based on monitoring and testing of Barrier I, a second, more permanent barrier (Barrier II) is authorized. Barrier II is a similar electric field barrier that covers a larger area within the canal and is constructed to last longer. It consists of two sets of electrical arrays and control houses, known as Barriers IIA and IIB. Each control house and set of arrays can be operated independently, but the ultimate goal is to operate both at the same time.

May 2006 Barrier IIA is completed, but due to safety concerns, it sits idle for nearly three years.

2007 Congress authorizes the Army Corps to complete Barrier II, to upgrade Barrier I and make it permanent, and to operate the barrier system at full federal cost.

September 2008 Flooding in the Chicago region sends water from the Des Plaines River tumbling over the narrow strip of land between it and the Sanitary and Ship Canal at several locations above the barrier site.

October 2008 Barrier I is shut down for maintenance. Repairs are made to allow Barrier I to remain in service for several more years until Barriers IIA and IIB are fully functional.

April 2009 Barrier IIA begins operating full-time at a strength of one volt per inch.

July 2009 Environmental DNA (eDNA) testing detects Asian carp DNA just south of the Lockport Lock, much closer to the barrier than previously believed. The eDNA test detects traces of Asian carp DNA in water samples within a 48-hour period.

August 2009 In response to the eDNA tests, the strength of Barrier IIA is increased to two volts per inch.

September 2009 Asian carp DNA is detected approximately one mile south of the barrier.

October 2009 Asian carp DNA is detected in the Cal-Sag Channel and Calumet River, beyond the electrical barrier.

December 2009 A 5.7-mile section of the canal is closed while scheduled maintenance on Barrier IIA takes place. Barrier I remains active. However, because Barrier I may not be effective in deterring juvenile fish, a fish toxin called rotenone is applied to the canal between the barrier and the Lockport Lock and Dam. At least 450 people from 20 agencies from the Great Lakes states and Canada report to Romeoville, Ill. to assist with the effort.

January 18, 2010 Asian carp DNA is detected in water samples taken Dec. 8, 2009, in the Calumet Harbor in Lake Michigan.

Reproduction in Rivers

If a substantial population of Asian carp establish themselves in the Great Lakes, scientists predict they will have to reproduce in river systems with 100 kilometers or more of open channel. There are 22 such rivers on the U.S. side of the Great Lakes. Four Wisconsin rivers could be especially favorable environments to carp reproduction-the Bad, Manitowoc, Nemadji, and Sheboygan rivers.

Source: April 12, 2005 U.S. Geological Service report submitted to the U.S. Department of Fish and Wildlife

Great Lakes ice rhythms

January 3, 2010

By Jennifer Yauck

Ice Feb 2007

Nearshore ice in Lake Michigan off Grant Park in February 2007. ~photo Michael Timm

Its hull a small black spot defiant against the surrounding field of white, the Coast Guard’s 140-foot Mobile Bay has cut through ice encumbering the waters of Green Bay each winter for three decades.

Icebreaking is such a massive task, the Coast Guard calls it Operation Taconite-keeping the way clear for commercial vessels in Lakes Michigan and Superior, the St. Mary’s River, and the Straits of Mackinac.

But aside from the Coast Guard-plus the occasional polar bear plunger or diehard ice fishermen-few humans pay close attention to the complex rhythms of lake ice building and receding that play out across the Great Lakes annually.

George Leshkevich, however, a scientist at the National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Laboratory (GLERL) in Ann Arbor, Mich., has been studying lake ice for several decades.

According to Leshkevich, differences in the lakes’ depths and regional air temperatures affect their potential to develop ice cover. Lake Erie, for example, is the shallowest of the lakes and typically sees the most extensive ice cover each winter, relative to its surface area. Lake Superior, farthest north and subjected to colder temperatures, is next on the list, followed by Lakes Huron, Michigan, and Ontario.


This map shows ice cover on Feb. 19, 1979, the last time Lake Michigan almost completely froze over. At the link below, you can watch animations of Great Lakes ice cover coming and going during the winters of 1973 to 2002. This Great Lakes Ice Atlas is compiled by the National Oceanic and Atmospheric Administration. www.glerl.noaa.gov/data/ice/atlas/daily_ice_cover/animations/animations.html

The extent of ice cover on the Great Lakes can also vary greatly from year to year, Leshkevich said.

For example, between 1963 and 2001, the maximum extent of ice cover on Lake Michigan over the course of a single winter ranged from 13 percent (in 1963-64) to 96 percent (in 1978-79) of the lake’s surface, according to one study. The average over that same period was 40 percent.

Along with such year-to-year fluctuations, the Great Lakes have seen an overall downward trend in winter ice cover over the last 30 to 40 years, said Leshkevich. That decline has coincided with an overall increase in global air temperatures.

Brash ice

Brash ice in northern Green Bay March 4, 2008. ~courtesy George Leshkevich/GLERL

Both natural variability and human-induced climate change can influence Great Lakes ice cover, said Leshkevich and fellow GLERL scientist Jia Wang. However, the more dominant influence is natural variability, which drives the year-to-year fluctuations in ice cover, Wang said.

“Our region is very complex because it is affected by two [natural] climate patterns,” said Wang. One pattern comes from the Pacific and brings either warmer “El Niño” or colder “La Niña” temperatures to the Great Lakes region. A second pattern that comes from the Arctic likewise affects the region’s temperatures with its warmer “positive” and colder “negative” phases.

The Great Lakes generally have lower ice cover in years when both the Pacific and Arctic patterns are warm, and higher ice cover in years when both patterns are cold, Wang said. When the patterns differ, they either moderate each other’s effects or the stronger pattern dominates. Last winter, the patterns combined to bring to the Great Lakes one of the more extensive ice covers of the past decade, a period during which ice cover was generally low.

Regional & Local Effects

Lake ice affects both the environment and the economy of the Great Lakes. Ice is good at reflecting sunlight, so its presence decreases the ability of the lakes to absorb heat and keeps them colder, said Jay Austin, a scientist at the University of Minnesota-Duluth’s Large Lakes Observatory.


Ice covers shallow Green Bay and the western and southern coasts of Lake Michigan in this satellite image from Jan. 16, 2009.

What’s more, said Austin, “the effect of ice is felt long after the ice is gone. The amount of ice during the winter can significantly affect lake temperatures throughout the summer.” His research shows that summer surface water temperatures of the northern Great Lakes-Michigan, Superior, and Huron-generally are warmer after winters with low ice cover, and colder after winters with high ice cover. He believes this is because ice cover delays the springtime stratification of the lake into layers of different densities, a phenomenon that promotes rapid warming of the surface layer in the summer.

Everything from algae to fish could be impacted by changes in lake temperatures and stratification that result from long-term changes in ice cover, according to Austin’s study.

Ice affects other aspects of the environment, too. In shallow areas, it can help protect the eggs of whitefish and other fall-spawning fish from currents and waves generated by strong winter winds. Ice cover also inhibits evaporation by shielding the lakes from dry, cold winter air. As a result, lake levels are often lower after winters with low ice cover, and higher after winters with high ice cover, said Wang.

Ice has implications for Great Lakes industries such as power production and shipping. Ice jams that form on the rivers connecting the lakes can constrict water flow and result in less water for downstream hydropower plants. Heavy ice can delay the opening of the shipping season and be a hazard to navigation, but it also can lead to higher water levels, allowing ships to carry more cargo.

Given ice’s environmental and economic importance to the Great Lakes region, scientists have good reason to continue studying it. In the future, Leshkevich plans to study ice cover thickness, and Austin is interested in developing numerical models that better explain ice’s connections to other phenomena. Wang is currently working on a model for forecasting ice cover.

Jennifer Yauck is a science writer at the UWM Great Lakes WATER Institute. GLWI (glwi.uwm.edu) is the largest academic freshwater research facility on the Great Lakes.

Forms of Great Lake Ice

  • Pancake ice – circular, flat pieces of ice with turned-up edges that are shaped by wind- and wave-driven collisions with one another
  • Brash ice – angular pieces of broken ice often piled on each other by wind and waves
  • Lake/black ice – clear ice that looks dark when viewed from an aircraft or satellite
  • Snow ice – milky white ice containing many bubbles, formed from water-soaked snow
  • Frazil ice – fine spicules or plates of ice suspended in the water, formed during the first stage of freezing
  • Source: George Leshkevich

The incredible, indelible cormorant

November 24, 2009

By Jennifer Yauck


Cormorants use their webbed feet to propel themselves through water in pursuit of fish and to grasp the branches of trees, where they sometimes roost and nest. ~photo George Jameson

Along with the ducks, geese, and gulls that frequent the waters of Milwaukee is a bird that may be less familiar to most landlubbers: the cormorant.

A relative of the pelican, these large, black waterbirds can often be spotted perched on harbor breakwalls or in other places near Lake Michigan during the summer months. They are skilled fishers that use their webbed feet and streamlined bodies to dive underwater-often to depths of 25 feet, and sometimes more-in pursuit of a meal. “They’re just as agile underwater as penguins,” said Ken Stromborg, a retired U.S. Fish and Wildlife Service biologist who has studied cormorants for nearly 25 years.  »Read more

Turning Great Lakes wind into energy

October 30, 2009

By Jennifer Yauck

Late this summer, Denmark inaugurated the world’s largest offshore wind farm, Horns Rev 2. Located nearly 20 miles from shore in the North Sea, the 209-megawatt wind farm consists of 91 turbines that together will generate enough energy for 200,000 households a year.

Closer to home, amid a growing interest in shifting from nonrenewable to renewable energy sources, the Great Lakes are attracting attention of their own as potential sources of wind energy. Ohio is currently working toward developing a pilot wind project in Lake Erie, while Ontario, Canada is seeking to develop projects in both Lake Erie and Lake Ontario. Meanwhile, Wisconsin is beginning to look more seriously at Lake Michigan’s wind-energy potential as the state works to meet its legislated goal of producing 10 percent of its electricity from renewable sources by 2015.

This map shows annual average wind power estimates at a height of 50 meters across the United States. The data used to make this map were screened to eliminate areas unlikely to be developed onshore due to land use or environmental issues. In many states, the wind resource is visually enhanced to better show the distribution on ridge crests and other features. The wind resource potential of Lake Michigan is as good as or better than areas of the Great Plains. ~Adapted from U.S. Department of Energy, National Renewable Energy Laboratory

But while offshore wind as an energy source has advantages-it’s cleaner and consumes much less water than fossil fuel sources, and has the potential to produce more energy than land-based wind-it also will require addressing various environmental, technical, economic, and legal issues.

“[Great Lakes offshore wind] is an idea that’s worth considering. It has pluses and minuses-and agencies, industries, power producers, and customers will have to figure out if it can be done with more pluses than minuses,” said Steven Ugoretz, an environmental analysis and review specialist with the Wisconsin Department of Natural Resources (DNR). Ugoretz also served on a workgroup that produced a report earlier this year for the Public Service Commission (PSC) on the feasibility of offshore wind in Wisconsin.

Spawning Grounds

When it comes to aquatic resources, one of the top concerns related to Great Lakes wind energy is how wind farms might impact fish and fish habitat. Thus far, wind farms have been built only in marine environments, so solid information on how freshwater fish might interact with wind facilities is largely lacking. “It’s a big question mark,” said Jill Utrup, a biologist with the U.S. Fish and Wildlife Service (USFWS).

However, experts have identified a number of factors they think will be important to consider as potential wind farm locations are evaluated. One of those, according to the PSC report and a recent report from the Great Lakes Wind Collaborative (GLWC), is whether the site is a critical spawning area. Lake Michigan’s mid-lake reef, for example, has site potential from an engineering perspective, but it is also an important spawning ground for lake trout, a fish the DNR and USFWS are working to restore.

Different types of wind turbine structures can be used in offshore wind projects. Gravity base or monopole structures (left two) are typically used in waters shallower than 30 meters. Tripod or quadropod structures (middle) are used in waters between 30 and 60 meters deep, and various types of floating structures (right two) are used in waters between 60 and 300 meters deep. ~courtesy James Schneider/UW-Madison

“It’s probably not a good idea to put these things where the trout are spawning, simply because we don’t know what the impacts would be,” said John Janssen, a scientist at UW-Milwaukee’s Great Lakes WATER Institute (GLWI) who studies the mid-lake reef. “We also don’t know what else might be spawning [at the mid-lake reef],” he said. “When we go over the reef with sonar, it seems to be a busy place, but we don’t know what it’s busy with.”

Utrup said that conducting surveys to identify important fish habitats can help minimize adverse impacts from wind farms. Surveys of breeding habits for birds and bats have proven useful for land-based wind projects, she said.

In areas without spawning habitats, wind farms would likely have less potential to adversely impact fish. In fact, wind farm structures might serve as spawning habitats in such areas and therefore actually have a positive impact, according to the PSC report.

Other Aquatic Issues

Another aquatic concern related to wind farms, cited in the GLWC report, is the potential for scouring of the lakebed by currents flowing around wind-turbine foundations. Scour could be beneficial or detrimental, said Janssen. It might expose more rock, thereby providing more spawning habitat for fish like perch, he said. Or, the exposed rock might act as an “attractive nuisance”-meaning fish might be drawn to spawn there, only to have their egg masses broken up by currents.

Other factors that could adversely affect fish-and therefore should be minimized or avoided-include noise and vibration from wind farm construction and operation, and the re-suspension of contaminated sediments during construction, according to the PSC and GLWC reports. Additional impacts that are harder to anticipate and detect in water than on land could also occur, cautioned Janssen.

On the plus side, wind farms could serve double duty as monitoring stations that would help scientists track fish and collect lake data, said Val Klump, GLWI director and scientist. “If we build these, we should build a monitoring network into them,” he said.

Overall, said Klump, “while offshore wind poses a number of technical and environmental challenges-like locating the structures to avoid habitat and ecological disruption-it also avoids some of the problems faced on land and has some real advantages. Given our increasing demand for energy, it’s definitely something we should be investigating.”

Jennifer Yauck is a science writer at the UWM Great Lakes WATER Institute. GLWI (glwi.uwm.edu) is the largest academic freshwater research facility on the Great Lakes.

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