Skip to main content

Taking on invasive species

By Anna Gaynor

It’s hard to believe that a few classroom pets could be a credible threat to the Great Lakes. And yet, that may be how the Louisiana swamp crayfish has snuck into the Chicago River and other freshwater bodies around the world.

Turns out, the crustacean makes a great animal for young students—right up until the end of the year when teachers are faced with a difficult dilemma.

“When you no longer need the pet in the classroom, it’s really hard to explain to the students that now we’re going to humanely dispose of this crayfish,” said Reuben Keller, PhD, a freshwater ecologist and an assistant professor in Loyola’s Institute of Environmental Sustainability. “It’s much easier to find a local creek.”

But that’s not the only way these large-clawed havoc wreakers can invade ecosystems, Keller said. Crayfish can sneak in with live bait that’s shipped up from the south, be used as lab animals, or be introduced as a source of food or sport.

So what can be done to keep crayfish and other invasive species in check?

Keller, who grew up in Australia and came to Loyola in 2011, is working on a new approach for this age-old problem.

An international dilemma

In terms of impact and literal size, cargo ships are among the largest transporters of invasive species. These massive vessels need to keep a constant weight: too light and they’ll roll over, too heavy and they’ll sink. When transporting small loads, the ships fill huge tanks in their hull with ballast water. When they take on more cargo, they pump the water back out.

That, however, also releases all the organisms that had been picked up from the previous port, introducing creatures from locales such as South America and Western Europe. By some estimates, ballast water can contain a thousand different species at a time.

It’s impossible for Keller and other ecologists to tell what organisms were introduced through ballast water but then failed to take hold. What they do know is which animals were successful at making trouble. So researchers identify the physical and environmental traits they have in common and classify what characteristics could signal a high-risk species.

“The best management and the best policy is to try and keep them out in the first place,” Keller said. “That means trying to predict what might arrive and figuring out what’s likely to be dangerous. We call that risk assessment for invasive species, so we try to look at species that might come in in the future and assess the risk, species by species.”

How they reproduce, how large they are, how they feed, what they eat, and how many eggs they produce a year are all features that ecologists study. Although the risk assessment models Keller develops and uses are relatively accurate, they’re not perfect.

A different approach

Keller has drawn a lot of attention from the scientific community throughout the Great Lakes region by joining forces with a group most ecologists are naturally suspicious of: economists.

“People get into ecology because they really like wild places, and people see a lot of economic forces are leading to the loss of those wild places,” Keller said. “As ecologists, we’re really interested in biodiversity and trying to conserve it, so you see the economists as being part of the driving force of what’s destroying the stuff that we love.”

Ignoring the sometimes thorny relationship between the two fields has placed Keller in front of policymakers, congressional staffers, and others to drum up support for new laws and grants.

“If you focus on the ecology, there’s just not enough there for managers and policymakers to use,” Keller said. “I started doing that work and I really wanted people to listen. Then I published it, people would read it, and it would stay within the academic realm.”

Keller also provides support for environmental groups fighting to put risk assessment and other prevention policies into effect on the national level. Peter Jenkins, an attorney and a consultant at the Center for Invasive Species Prevention, which backs legislative reforms and awareness programs, believes Keller’s work is bridging two important fields.

“In the real world, you can go in and make arguments about saving animals and saving wildlife, but it’s also very helpful to have backing with arguments based on economic cost benefit analysis—because economic arguments carry a lot of sway in the policy circles,” Jenkins said. “If you’re arguing for a particular policy and you can show that it makes economic sense as well as environmental sense, your task is easier.”

These kinds of policy decisions can range from getting cargo ships to discharge their ballast water in the ocean before heading into freshwater ports. Or on a smaller level, it can include an aquarium dealer who wants to introduce new species to the US market. Keller can use risk assessment models to determine which species are likely to be problematic if introduced in a new environment.

“If you go to the aquarium trade and tell them, ‘We want you to keep out all of these species,’ ” Keller said, “they’ll say, ‘Are you absolutely sure? You can’t unless you’re absolutely sure, because keeping them out represents lost revenue for me.’ ”

Beyond the science

Often policymakers and animal and plant dealers will argue that the cost of implementing these strategies or accidentally keeping a benign species out of the commercial market will end up being more costly than any repercussions. That’s where economist and frequent co-author, Michael R. Springborn, finds Keller’s work indispensable.

“You can’t think about that ecology in a vacuum because it’s exactly human behavior that’s leading to the problem,” said Springborn, an associate professor at the Department of Environmental Science & Policy at the University of California-Davis. “It’s trade and travel essentially that’s moving these species around, and that activity is going to be a main focus for policy interventions. The social science and the economics become critical to try and do that in an intelligent way and in a way that doesn’t impose unnecessary costs.”

That said, Keller hasn’t been content with just economics. In May 2011, he organized a conference of experts in a wide range of fields to discuss invasive species. It turned out so successful that Keller and two collaborators pulled together a collection of papers and essays—called Invasive Species in a Globalized World—based off the conference.

In addition to getting input from history and social science experts, the book features chapters from a children’s book author on developing a superhero who defends the Great Lakes and a civil engineer on testing structures that capture or damage the eggs of the troublesome common carp in Australia.

“I’ve done some good ecology, and you talk to people about it and they say, ‘That’s nice,’ and then they move on,” Keller said. “But getting people to actually listen to what you’re saying or trying to come up with something that’s socially relevant that you can get policymakers and managers interested in, you’ve got to go beyond ecology. I learned that pretty quickly.”