WBEZ | Science

Buckthorn draws out coyotes, cripples native frog development

Mon, 20 May 2013 10:42:00 -0500

Ecologists have long known of buckthorn’s ability to push out native plants, but two new studies from Chicago scientists suggest the woody shrub also changes the distribution of large mammals like coyotes, and causes spinal defects in unborn frogs.

"We already knew that the buckthorn was outcompeting other plant species," said Seth Magle, director of the Lincoln Park Zoo’s Urban Wildlife Institute and author of one study currently in publication. "But no one had looked at the mammal community to see if they’re affected. And it turns out that they are."

An invasive species imported from Europe as an ornamental plant, buckthorn has overrun many native ecosystems, including oak savannas and prairieland. Its spindly branches form a dense undergrowth that blocks sunlight from native plants, providing cover for crime in some urban corridors. According to the new study, forthcoming in Natural Areas Journal, white-tailed deer were more likely to show up in sites without buckthorn, while coyotes and opossums were more common in sites invaded with buckthorn.

An Urban Wildlife Institute intern, Marian Vernon, first noticed the trend. Magle encouraged her to see if the data would bear out her observation. Vernon, now a PhD student at Yale University, and her colleagues used motion-triggered infrared cameras to document the appearance of different mammal species at 35 Chicago area sites.

The study also found seasonal changes in association with buckthorn. Coyotes shifted into sites with buckthorn from spring to summer, affecting the distribution of one of their preferred prey species, white-tailed deer.

While buckthorn may change the distribution of some mammals, another study suggests it directly harms amphibians.

Buckthorn emits a chemical called emodin, which has a wide variety of bioactive properties. Previous studies found emodin has laxative properties when eaten by some animals, and is allelopathic, meaning it inhibits the growth of other plant species nearby.

New research from Northern Illinois University student Allison Sacerdote-Velat and her PhD advisor Richard King found emodin also affects frog embryos, causing fatal kinks in their developing spines. The research is slated to be published in an upcoming edition of the Journal of Herpetology.

The effects hit native species harder than African clawed frogs, a common test species for environmental toxicity studies. Buckthorn produces emodin in its roots, fruit, bark and leaves, which it drops early in the season to salt the earth, so to speak, against competitors. Buckthorn in Illinois is particularly aggressive in its ability to invade wetlands, strengthening its impact on amphibians who live and breed in those areas.

The study found high levels of emodin coincided with the breeding activity of several Midwestern amphibian species, including western chorus frogs and blue-spotted salamanders.

“[Buckthorn] litter is probably changing the aquatic invertebrate community,” Sacerdote-Velat said. “Over time these factors build up and you start losing species diversity.”

The authors of both studies noted the need for further research. Magle pointed out that each study site had only one camera. Small mammals and birds are not big enough to set off the motion-triggered cameras, so it’s not clear what effect, if any, buckthorn might have on other species.

For Magle, the research is a reminder that small ecosystem changes can have cascading effects.

“It shows us that our urban areas are ecosystems,” he said, “where everything is connected to everything else.”

More on methane: EPA reexamines potency of greenhouse gas

Mon, 13 May 2013 17:12:00 -0500

In the debate surrounding the United States' natural gas resources, it is often noted that methane, the primary component of natural gas, is 21 times more potent a greenhouse gas than carbon dioxide. There are two main issues with that statement, although that is the figure used by the Environmental Protection Agency.

Carbon dioxide, whose concentration recently reached a long-feared milestone, remains the most important greenhouse gas trapping heat in the atmosphere. But as we open more oil and gas wells, even small amounts of methane leakage could tilt the balance of greenhouse gas emissions from new fossil fuel resources.

The ratio of a molecule’s ability to trap heat, and thus cause global warming, relative to one molecule of carbon dioxide is called its global warming potential. The EPA recently proposed raising raising methane's global warming potential to 25. Amending the number to 25 would be a 19 percent increase — significant, but only keeping pace with revisions codified more than six year ago in the fourth Intergovernmental Panel on Climate Change (IPCC) report. The 21 figure used by EPA was first put forth in the 1990s. IPCC upped it to 23 in 2001. Its fifth report is expected later this year.

The other issue is that methane is especially short-lived. Unlike carbon dioxide, which persists in the atmosphere for 500 years, methane only lasts about 12 years in the atmosphere before chemical reactions break it down. EPA typically estimates global warming potentials based on 100-year timescales, but estimated over a 20-year time scale methane could be more than 50 times more potent than carbon dioxide.

Why does that matter? In the short-term, methane and other short-lived gases could exacerbate near-term climate impacts, just as the world struggles to get the real driver (CO₂) under control. One California congressman recently proposed a bill targeting those short-lived pollutants to mitigate near-term climate change.

Researchers at NOAA and the University of Texas at Austin are working on a review of greenhouse gas emissions from natural gas. An EPA revision recently rolled back its estimate of emissions from one part of the fracking process but simultaneously upped its most recent figure for emissions from fracking itself.

Those revisions came on the heels of EPA’s separate announcement that it could raise methane’s global warming potential to 25. In the words of Anthony Ingraffea, a Cornell professor of civil and environmental engineering and noted critic of shale gas production on climate change grounds, “sometimes the EPA giveth, sometimes it taketh away.”

EPA will accept comments on the proposed rule until May 17. Comments should reference docket No. EPA-HQ-OAR-2012-0934.

You don't have to be smart to have your own show

Mon, 29 Apr 2013 08:00:00 -0500

Olympic swimmer and apparent babe magnet Ryan Lochte has a new reality show called What Would Ryan Lochte Do? In the first episode, he reminisces about his glory days, makes a half-hearted attempt at dating and steals his brother's toothbrush. So, he basically does nothing.

"Seriously, how are they gonna get enough material?" asked anchor Mike Jerrick after an unintentionally hilarious interview with Lochte on Good Day Philly.

As a full first season of WWRLD looms ahead, I ask myself the same question.

Over the past twenty years, beginning with The Real World in 1992 and skyrocketing with the U.S. version of Survivor in 2000, reality TV has become a staple of American television. However, the clever concept of filming "real people in real situations" has lost much of its magic since then, with clearly scripted (and often mind-numbingly awful) reality shows like Jersey Shore and My Super Sweet Sixteen depleting brain cells for generations to follow.

Why do we enjoy watching ridiculously dumb people make complete fools of themselves? Do we relish tearing apart the Jessica Simpsons, Real Housewives and Honey Boo Boos because mocking them makes us feel better about our own lives?

In my opinion, the worst reality TV offenders are Teen Mom (because you have to make it on 16 and Pregnant first), Toddlers & Tiaras (in what universe is dressing your 5-year-old like a street prostitute considered cute and in good taste?), Keeping Up with the Kardashians (why are these people famous again?) and The Biggest Loser (because losing weight that quickly is horribly unsafe at any size, period).

Luckily, not all reality TV shows are hackneyed and irresponsible fodder for the masses. Competition series like Top Chef, Best Ink, Face Off and Project Runway feature contestents who excel in a certain field (for these shows: gourmet cooking, tattoo art, prosthetic makeup and fashion design, respectively) and rely on pure talent in order to succeed. As skilled professionals, they are fascinating to watch, not to mention wholly deserving of the platform they've been given.

I will admit that the singing and dancing shows can be a bit cheesy at times, but at least the starry-eyed hopefuls on American Idol, The Voice and So You Think You Can Dance showcase talents that extend beyond the realm of petty arguments and party fouls.

Other inspiring and thought-provoking examples of reality TV-done right include Undercover Boss, The Amazing Race, Deadliest Catch and my newest favorite, Pit Bulls and Parolees on Animal Planet. I'll take adorable animal rescues over The Bachelor any day, thank you very much.

What are your favorite (and least favorite) reality shows? Leave a comment below, send me a tweet @leahkpickett or join the conversation on Facebook.

Botanic Garden gets over-watered by storms and is saved by plants, Army

Thu, 25 Apr 2013 23:34:00 -0500

Chicago's "garden on the water" got over-watered last week.

With more than six miles of shoreline, the Chicago Botanic Garden offers an idyllic green scenery along a waterfront. But when last week's inundation sent the garden’s lake levels soaring by more than five feet, the scene looked more like a swamp. And it was the actions of native plants – and the U.S. Army – that saved it.

The rising water swallowed stone lanterns on the shores of the Japanese Garden. In the past, such flooding would have sucked soil away from the garden’s shorelines. Thanks to an aggressive perennial plant initiative that has tied up lakefront soil with native plant roots, however, many areas of the garden weathered the storm with ease.

“Within a few weeks you won’t even know anything ever happened,” said Bob Kirschner, director of restoration ecology at the Botanic Garden. Water levels should return to normal by Sunday night, he said, more than 10 days after the lakes began to rise.

In 2012 the Army Corps of Engineers helped the Garden flatten out its sloping shores, which had been made steeper by years of erosion. Like many landscaped lakefronts and urban waterways, the Garden once had turf grass right down to the water’s edge. When turf grass goes underwater for days on end, it dies. Then the waves washing against that edge start to erode the soil. That process feeds upon itself, chipping away at the earth until you are left with vertical banks.

Over the past 13 years they have planted more than 450,000 native plants representing hundreds of species. Plants like riverbank sedge and blue flag iris were selected for their ability to survive extended flooding. While conventional flood control infrastructure like sheet piling and stone riprap can help forestall erosion, it can also create “biological deserts,” Kirschner said, by isolating what might otherwise be a thriving ecosystem where land slopes gently into shallow waters.

“Native plants don’t change the volume of the water we store here,” Kirschner explained, “but they change the resiliency of the ecosystem so it can recover.”

Native plants aren’t just for botanic gardens and ecologists. The Skokie River frequently spills over into the Garden, but not before running through 20 miles of north suburban development. If small landowners took an ecological approach to their backyard landscaping, they could have a significant impact on the river’s flashiness.

“Your friends and neighbors upriver largely control your destiny,” Kirschner said, “but you’re controlling the destinies of people downriver from you.”

Of course native plants have their limits, too. Climate change will likely intensify precipitation extremes, leading to more severe floods and droughts. But the Botanic Garden’s native plants survived even worse floods in 2008, and didn’t need any water during last summer’s drought.

Chris Bentley writes about environmental issues. Follow him on Twitter at @Cementley.

Study finds ample U.S. graduates to fill STEM jobs

Thu, 25 Apr 2013 16:16:00 -0500

As Congress considers a makeover of the country’s immigration policies, they’ll discuss an expansion of the H-1B temporary visa program for high-skilled foreign nationals. The H-1B program is popular among employers, including several in Illinois, who have long asserted that U.S. colleges and universities are not producing enough graduates in the science and technology fields.

But a new study from the Economic Policy Institute, a Washington-based non-profit which receives about 30 percent of its funding from labor unions, finds that there are more domestic graduates in those fields than the market can accommodate. The study looks over time at domestic graduates in the fields of Science, Technology, Engineering and Mathematics (or STEM), as well as temporary guest worker inflows on the H-1B, L-1, and Optional Practical Training visas, where large shares of visa holders work in IT jobs.

“There are, as we found before, a large supply of STEM graduates,” said Hal Salzman, a professor at Rutgers University and one of the authors of the report. “We just can’t see in the numbers a failure of U.S. colleges and universities to produce sufficient supply,” he said. Salzman co-authored the paper with professors Daniel Kuehn of American University and B. Lindsay Lowell of Georgetown University.

H-1B workers account for thousands of jobs in Greater Chicago, which historically has been one of the top five hubs in the nation for workers on that visa. In federal fiscal year 2011 more than 11,000 skilled workers came to Chicago on H-1B visas, with India-based IT consulting company Infosys employing nearly one in ten of them as computer programmers. Suburban Hoffman Estates and Schaumburg also accounted for an additional 4,300 H-1B workers. Average wages for H-1B workers in these cities ranged between $63,000 and $69,000.

The study finds that the domestic supply of students in STEM fields responded to industry demand as expected during the 1990s and into the early 2000s, but that a shift occurred in 2004 when companies began shifting their search for talent overseas.

“If you look at what happened in the lead up to the dot-com bubble to the peak, you can see that wages rose steeply, unemployment was fairly low, right up until the 2001 peak, and the result was that the number of students pursuing computer science overall doubled,” said Salzman, “it seems that students are very responsive to market signals.”

The authors find, however, that after the recovery from the dot-com recession, employment in the IT sector began picking up, but wage growth did not resume. They attribute this to an increasing reliance on foreign workers for those jobs. “The guest worker supply, understandably, coming from low-wage countries, is very plentiful, (and) will continue almost despite whatever wage levels are here because they’re still better than what (they) would be in their home country,” said Salzman.

One result of the divergence between demand and wages for IT workers, said Salzman, is that many American STEM graduates are opting to work in other fields. The study finds that one-third of computer science graduates and nearly half of engineering students fail to go into jobs related to their degrees because they couldn’t find jobs, or because they felt they had better career prospects in other fields.

“It’s basic Econ 101,” said Salzman. “If you bring in a lot and flood the market, it depresses wages (and) lowers job quality. And we’ve certainly seen that in interviews we’ve done over the years, where people think what used to be good jobs, particularly in IT, are no longer high-quality jobs. They think they’re unstable, wages have not gone up and they counsel their kids to go elsewhere.”

The STEM report comes as Congress picks over a proposed new immigration overhaul. The legislation by the so-called Gang of Eight would dramatically expand employers’ access to skilled, temporary foreign workers, while also imposing additional controls. The H-1B visa program, currently capped at 85,000 visas annually for highly-educated foreign nationals, would over time grow to 180,000 visas. It would also prohibit large companies from staffing more than half of their workforce with H-1B visa holders, and would require companies to pay higher wages to those workers.

Very few legislators in Washington question the assumption that U.S. companies have been unable to locate qualified, STEM-educated American workers. Two separate bills proposed in the Senate in recent months have both looked at increasing the H-1B cap. Large companies such as Microsoft have been particularly vocal about the need to change immigration policies to allow for more temporary, skilled workers.

“I don’t think the argument here is that foreign workers aren’t good or they aren’t productive,” said Lowell. “I think the argument is yeah, I think we want foreign workers we want employers to have access to, but the question really is, in what amount, and is more better?”

Lowell and the other study authors said the devil will be in the details of any changes to immigration policies. They point out that while the immigration bill does propose higher wages for H-1B workers, it would still allow these workers to be paid 20 percent less than the average wage for those industries.

Odette Yousef is WBEZ’s North Side Bureau reporter. Follow her at @oyousef and @WBEZoutloud.

Contaminated water trial starts in Chicago

Mon, 22 Apr 2013 15:56:00 -0500

The trial has started for a former suburban Chicago water official accused of lying about how the village drew drinking water from a tainted well for decades, apparently to save money.

The one-time Crestwood official, Theresa Neubauer, has pleaded not guilty.

A federal judge asked Monday during jury selection whether any would-be jurors ever worried about the quality of the water in their communities. At least one said he had.

Prosecutors say Crestwood continued drawing drinking water from the well even after environmental officials warned cancer-causing chemicals had oozed into it.

Neubauer is the first official from the village of 11,000 to go to trial over the allegations.

Earlier this month, co-defendant Frank Scaccia chose to plead guilty rather than take his case to jurors.

Report links Chicagoans' distance from trauma centers to higher mortality rates

Thu, 18 Apr 2013 16:31:00 -0500

Chicago-area gunshot victims who are shot more than five miles from a trauma center have a higher mortality rate, according to a new public health study released on Thursday.

Dr. Marie Crandall, a professor in surgery/trauma care at Northwestern University, analyzed 11,744 gunshot patients from 1999-2009. The data found 4,782 people were shot more than five miles from a trauma center. Those patients were disproportionately black and less likely to be insured.

“We have demonstrated that incident proximity to a trauma center has a positive effect on survival outcomes for gunshot wound victims,” says Crandall’s report, which the American Journal of Public Health published. Trauma centers take care of more severe injuries such as stabbings, car crashes and gunshot wounds (GSW). The Chicago area has seven Level 1 adult trauma centers.

Among the study’s findings: The crude mortality rate for blacks shot within five miles is 6.42 percent; whereas outside of five miles, it is 8.73 percent. This would translate into 6.3 excess deaths per year. Crude mortality is not adjusted for variables such as severity of injury. Crandall said previous research had shown difference in transport times but didn’t really affect survival. This new research drills down to Chicago and focuses solely on gunshot wounds.

“Our study is different. The heterogeneity of trauma patients are such that if you’re not specific about your research question, you might find different results,” Crandall said. “The vast majority of penetrating trauma in the city of Chicago is gunshot wounds and very relevant to our current crises, we decided to limit the data set and analysis to that population.”

According to the study, “We have identified the southeast side of the city as a relative trauma desert in Chicago’s regional trauma system that is associated with increased GSW mortality. We hope that the data presented will inform discussions aimed at optimizing regional trauma care in Chicago and will also aid in planning regional trauma systems in other urban settings.”

In 2011, a WBEZ analysis suggested that when it came to ambulance run times from the scene to trauma centers, there were disparities. Put simply, patients living on the Southeast Side face longer ambulance run times than other residents in the city. Specifically, they have to travel an average of 50 percent longer to get from the scene of an emergency to a trauma center. More than half of the trauma-related ambulance runs that originate in that part of town exceed 20 minutes, which is considered a professional standard within the city. Those neighborhoods include Hyde Park, Woodlawn, Pullman, South Shore and the Southeast Side.

Trauma center access has long been a contentious issue for some activists. And there have been questions about whether an additional trauma center would save lives on the South Side.

In 2010, a stray bullet killed youth activist Damian Turner. He was shot on the South Side, near the University of Chicago hospital. But he was transported approximately eight miles downtown to an adult trauma center at Northwestern University. Ninety minutes later he died.

A group called Fearless Leading by the Youth believes if the university had its own trauma center, Turner would have gotten treatment sooner and lived. For years, members have protested the University of Chicago, which had a trauma center for adults from 1986-1988. It closed after hemorrhaging $2 million a year, though they still serve children. At the time doctors said a majority of patients had no health insurance. Recently the issue flared up again when the University of Chicago opened a new $700 million facility with no additional trauma care.

Victoria Crider, a member of FLY, says the new study will help activists’ cause.

“We plan on using this data to show that this is exactly what it says: a relationship between whether or not you live or die and the time it takes you to get to the nearest trauma center,” Crider said.

The study acknowledges the costliness of trauma centers. Crandall writes that trauma centers could be rebalanced on the basis of volume and proximity as opposed to capacity. In addition, she writes that existing local hospitals could take in trauma patients in a possible Level 2 capacity.

Natalie Moore is WBEZ's South Side Bureau reporter. Follow her @natalieymoore.

That giant gaping hole on the Southside of Chicago? It may not be a sinkhole after all

Thu, 18 Apr 2013 14:57:00 -0500

A 40-foot hole opened up on a residential street on Chicago’s South Side. It swallowed up three cars and a man who suffered non-life-threatening injuries. Many are calling it a sinkhole. But that might not be quite right.

Anthony Randazzo is professor emeritus at the University of Florida’s geological science department and president of Geohazards, Inc, a business that consults on sinkhole issues all around the world.

He says that the 40-foot hole is actually a giant pothole.

“Unfortunately, journalists don’t like to be told what they have is a pothole and not a sinkhole because that’s far less glamorous,” he said.

Randazzo said sometimes companies that fix these kinds of problems also misuse the term. “Sinkhole” sounds far more terrifying than “pothole” and so they can charge more to fix the issue.

Here’s the real difference according to Randazzo:

Water chemically dissolves limestone, and other similar stones, over many years, forming underground caverns. If one of those caverns collapses, then you got yourself a sinkhole.

In Chicago, a water main broke, perhaps due to the extreme downpour. That physically-- not chemically which is key-- eroded the soil. The result was a pothole.

In Illinois, we don’t have much limestone, so true sinkholes are unlikely. They are more common in places like Florida, where limestone is present.

But don’t be deceived, said Randazzo, potholes can be a real problem for big cities.

“There is a rapid deterioration of infrastructure in major cities,” said Randazzo. “You can expect to see more of this.”

If potholes don’t sound quite terrifying enough to describe the pictures and videos you’ve seen today, feel free to tweet me your alternative titles at @shannon_h or leave them in the comments.

James Hansen drops the mic

Mon, 15 Apr 2013 21:59:00 -0500

In response to years of what he views as dithering and ineffectual responses by government to the problem he helped identify, climate scientist James Hansen cited a moral obligation in leaving his post at NASA to campaign more actively for political and legal efforts to limit greenhouse gas emissions.

Hansen spent more than four decades forging the scientific basis for manmade climate change. In 1988 he was among the first to sound off on global warming’s hazards, and earlier this month he announced his next paper would be his last for NASA. (He told The New York Times he would continue to publish after retirement and had not ruled out taking an academic appointment.)

So-called “doom-and-gloom” projections of future climate change have been derided for their pessimism, or maybe more often for the unpleasantness of their messengers, to the point that addressing climate change on these terms makes one seem petulant or gauche — no one really wants to hear it. The national political conversation completely buried talk of the climate problem after national cap-and-trade legislation imploded in 2010.

Hansen’s final paper, currently in press, is scientifically rigorous, with seven pages of references, but it makes an impassioned plea for humanity to confront the consequences of climate change and fossil fuel consumption as an existential threat to society:

“Burning all fossil fuels, we conclude, would make much of the planet uninhabitable by humans, thus calling into question strategies that emphasize adaptation to climate change.”

Such an assertion is not unexpected coming from Hansen, who has been criticized for his rhetorical flourishes, even by colleagues who respect his work. Earth won’t turn into “a Venus-like baked-crust CO₂ hothouse,” (a claim he has made in the past), at least until the Sun’s brightness increases over the next billion years and helps boil off the oceans. But, the paper reads, “the planet could become uninhabitable long before that” due to anthropogenic warming.

Scientifically, much of the debate fixates on nailing down the planet’s “climate sensitivity” — how much warming actually occurs per unit of extra energy in the atmosphere. Looking at physical evidence of ancient climate change, the paper calibrates a computer model against times when greenhouse gas levels were comparable or higher than they are today.

The authors calculate an average warming of about 16 degrees Celsius if we burn available fossil fuels. Previous scientific publications have suggested temperature increases on that scale could practically wipe out grain production in many parts of the world, and severely diminish the ozone layer that protects us from cancer-causing ultraviolet radiation. Worse, it could get so hot in all but the world’s very mountainous regions that anyone outside would overheat, suffering hyperthermia.

The paper — co-authored by Hansen’s NASA and Columbia University colleagues Makiko Sato, Gary Russell and Pushker Kharecha — says current models exaggerate the slow response time of ice sheets, and assume the climate system’s own inertia will forestall catastrophic changes longer than they actually will. Hansen’s earlier research was instrumental in showing how, on a human timescale, oceans and massive ice sheets on Greenland and Antarctica mask the planet’s response to our feverish emissions of greenhouse gases. These systems have a long response time to human-made warming so, as Hansen writes, “observed climate changes are only a partial response to the current climate forcing, with further response still ‘in-the-pipeline.’”

Thus, his earlier dig at adaptation strategies. Broadly, there are two key categories of climate change action: mitigation and adaptation. Mitigation means pursuing efforts that limit or reduce greenhouse gas emissions. Adaptation assumes a certain amount of warming and asks what humans can do to adjust to their new environment in the future. If our current course of action even flirts with consequences like those suggested in this paper, Hansen and his co-authors suggest, adaptation will be impossible — a moot point.

By the scientific assessment of Hansen et al., an extra 12 watts of energy per square meter in the atmosphere could have devastating effects. But could that much warming happen? Yes, they conclude: there are more than enough fossil fuels available to cause this warming (coal alone could do it, not to mention with the help of unconventional sources like oil sands and natural gas freed up by fracking).

“It seems implausible that humanity will not alter its energy course as consequences of burning all fossil fuels become clearer,” reads the paper’s conclusion. “Yet strong evidence about the dangers of human-made climate change have so far had little effect. Whether governments continue to be so foolhardy as to allow or encourage development of all fossil fuels may determine the fate of humanity.”

Asian carp might have entered lakes, but so what?

Thu, 11 Apr 2013 05:00:00 -0500

New evidence suggesting Asian carp may already be in the Great Lakes basin has renewed fears that the invasive species could pose an existential threat to the area’s lucrative fishing industry.

“The fact that fish may already be in the lake does not mean it’s game over,” said Lindsay Chadderton, aquatic invasive species director for The Nature Conservancy. “The real risk is that if we continue to debate and don’t act, we may lose that opportunity.”

But the charismatic fish, infamous for their tendency to leap out of the water (though they're unlikely to do so in the deep waters of Lake Michigan), are no shoe-in when it comes to colonizing the Great Lakes.

“In my view, the Mississippi River basin is the least of Lake Michigan's worries, because the habitat is so warm, rich and shallow that its denizens would be completely unfit in cold, dilute, deep Lake Michigan,” said Russell Cuhel, a senior scientist with the Great Lakes WATER Institute. To reproduce, carp need access to rivers where there is an amply flowing water column to help disperse their eggs. That isn’t common in most of the Great Lakes, but some places, including Lake Erie and the Detroit River, could provide the right conditions.

The sea lamprey, another invasive species that decimated the Lake Trout population, shares an Achilles heel with Asian carp. Like the carp, lamprey head upstream to breed. To control their spread, the Great Lakes Fishery Commission applies specialized poisons that kill young lampreys in streambeds before they reach open water and mature. It’s possible that if carp do establish themselves in the Great Lakes, a similar strategy could control their population. But it’s no sure bet.

“Invasive species never do what we expect them to do,” Chadderton said. “They’re opportunistic. That’s why they’re good invaders.”

At any rate the jury is still out on whether carp could flourish in the unfamiliar Great Lakes ecosystem. Unlike carp, the wildly successful quagga and zebra mussels, which first arrived as stowaways in ship ballast tanks, breed where they live and are capable of producing 1 million eggs per year. In many areas of the Great Lakes they now blanket the lake floor, and have become by far the most dominant species by biomass in Lake Michigan.

Those mussels have devoured much of the available phytoplankton — the same food source carp depend on — posing another challenge for the new invader. Research suggests that carp might be able to survive on other food sources, however, including mussel feces. And even minor competition from the voracious carp, which can eat up to one fifth of their body weight in plankton each day, could place further pressure on young walleye and other sport fish that also eat plankton in their larval stage.

While the lamprey and the equally disruptive alewife entered the Lakes on their own volition, they are the exception to the rule. Recent research published by Cuhel and Carmen Aguilar in the Annual Review of Marine Science found few of the many invaders since 1936 established themselves by swimming into the Lakes. Most were unintentionally transported or released.

“It only takes one idiot to infect a location with an exotic [species],” Cuhel said. “One fisherman with a bait bucket can be worse than river flow.”

Cuhel won’t weigh in on policy or engineering proposals to physically separate the Great Lakes and Mississippi basins, or treat locks with chemicals that could clear out carp and other invasive species before they enter Lake Michigan. But others have called expensive efforts to keep out invaders a foolhardy investment.

There are dozens of species in the Great Lakes basin that don’t currently exist in the Mississippi, and nearly a dozen more vice versa. Aquatic invasive species protections could defend those populations from cross-contamination. What’s more, environmental agencies already spend hundreds of millions of dollars each year managing algal blooms, sea lamprey and mussels. That makes an economic argument for prevention measures, Chadderton said, even if the carp don’t turn out to be good colonizers of most Great Lakes waters.

“The trouble with any invasion is that there will always be evidence on both sides. So do you let the experiment run?” Chadderton said. “The most prudent management option is to prevent establishment.”