Exotic species may create havoc when they invade a new environment. Notre Dame’s David Lodge is doing all he can to help maintain the equilibrium.
By Erik Ness
(Notre Dame Magazine, Winter 2003-2004)
Sitting in the stern of his sturdy gray lab boat, David Lodge is sexing crayfish. Reaching into a white plastic bucket, he plucks a rusty crayfish from the tangled mass of scratching, frothing, gnawing crustaceans. The angry critter waves his pincers in futile menace as the Notre Dame ecologist applies his calipers with practiced ease.
Jody Murray sits amidships, clipboard ready. The rookie Notre Dame grad student is on her first crayfish roundup, where the numbers of northern crayfish and the invasive crayfish called rusties are being counted in Lake Ottawa on Michigan’s Upper Peninsula. She swiftly tallies as Lodge calls out carapace length, sex, molt status and the occasionally indignant “Ow!” when a claw makes it through his defenses. “All rusties,” he declares after the last one, then revs the motor and bears down on the next buoy.
It may be an overcast July day in the Upper Peninsula, but skimming across the light chop on Lake Ottawa it’s hard to avoid the seductive tune of this little gem of a northern lake. Martial spruce, shimmering aspen and bright maple rim the bluish green water, which is clear to a depth of 20 feet. The bottom is a jumble of rocks and the occasional log, and it seems each crevice conceals yet another crayfish.
Forty traps were set yesterday, each baited with a half-pound of beef liver. Pulling the next, Lodge keeps a hopeful eye for the northern crayfish, the native in these parts. In 1931 a survey of northern Wisconsin and Michigan found no rusties, but by 1960 the Ohio Valley native was common.
Most people can’t tell the rusties from the northern crayfish, but they can see the difference in lakes invaded by the rusty. A 1937 study of Lake Ottawa, for example, detailed an underwater tapestry of submerged plants, 14 species in all. These floating nurseries were hearth and home to countless game fish striving for eventual big-fish status. That refuge was shredded in the last decade as the rusties became dominant; only a single species of submerged plant holds on in a small bay. Drop live bait and you’re as likely to pull up a rusty crayfish as bass or walleye. According to Jerry Edde, fisheries manager for the Ottawa National Forest, such invasive species as the rusty crayfish are the single biggest threat to this legendary fishing landscape.
By day’s end we’ve loaded two coolers. The score: invasive species 1,871; native species O. The invasive species can’t go back in the lake, so science steps aside for the culinary arts. We cull out the big ones and make a shopping list: garlic, butter and—as a precaution—more ice: The rusties are plenty cool for food safety, but Lodge wants them comatose before we get back to the protected lakes at the University of Notre Dame Environmental Research Center (UNDERC). The research center is on the Wisconsin-Michigan border, and there are no rusty crayfish in any of the 30 lakes on the site. Lodge intends to keep it that way.
Trapping crayfish brings David Lodge back to his roots. In 1983 he was a young postdoc at the University of Wisconsin, a freshly minted Rhodes Scholar in search of a research topic. His adviser suggested the rusty crayfish, and Lodge began the trapping that continues today. “You got to see a lot of lake, and you didn’t have to think too much,” the ND professor of biological science recalls. “Except for the time I thought I was going to die on Trout Lake. It was one of those summer thunderstorms. I could see it coming; I just couldn’t go fast enough.”
He escaped, of course, bringing his crayfish work to Notre Dame in 1985 and delving ever deeper into the burgeoning field of invasion ecology. Ecologists identify a handful of major threats to global biodiversity: climate change, nitrogen pollution, and overharvesting of forests and fisheries, among others. Also high on the list: invasive species. These are organisms that have colonized new territory to devastating biological effect, displacing native flora and fauna and remaking natural systems in their image. “There is a strong consensus among ecologists that this should be one of the major environmental concerns of our day,” says Lodge.
But it’s a difficult problem to grasp. Each invasive species is a fresh face, traveling via different pathways and affecting different terrain in different ways. “In aggregate, the effect is an enormous change,” explains Lodge. Invasions are a natural part of evolution, but modern transportation has radically increased the rate at which organisms are being moved around, the distances they can move and how fast they get there, alive. “Invasions and other environmental things tend to have built-in delays,” he says. “It’s often hard to know what the result is going to be for 10, 20, even 100 years.”
The effects are varied too. For example, the native crayfish in Lake Ottawa are widespread; their absence here does not even begin to threaten extinction. Yet invaders can significantly alter our experience of place.
“I’ve always loved snorkeling in patches of underwater plants,” Lodge says, thinking of Lake Ottawa. “It’s sort of the aquatic equivalent of a walk in the rainforest. That’s where the biological action is in lakes. Plants create this forest, this structure, food for all the other organisms to eat. Any angler knows that’s where you go fishing. The rusty crayfish clearcut that underwater forest, which has an immediate effect on one of the things that people value about lakes. If you have grown up in a place, or lived in a place for a long time, you appreciate whatever is unique and distinctive about where you live. That includes the plants and the animals and the way the lakes look.”
The overall price tag is huge, and the economic impacts varied. In 1999 Cornell ecologist David Pimentel estimated annual damage in the United States at $123 billion. Alien weeds clog wetlands and western rangeland at a cost of $35.5 billion; these figures include reduced productivity of pasture for livestock and of wetlands as fish and wildlife nurseries. Foreign insect pests cost $20 billion in direct damage to crops and property. Organisms causing human disease run a $6.5 billion tab for prevention, monitoring and lost productivity. Beyond the economic damage, more than 40 percent of species on the U.S. Department of the Interior’s endangered or threatened species lists are there because of invaders.
With that kind of money at stake, the Clinton administration finally took note, issuing an executive order in 1999 for cabinet-level coordination of the battle against invasive species. On a visit to the capital that year Lodge stopped by the coordinating office to see how things were going; the next year he was selected as the first to chair the scientific advisory committee. He remains a member today.
In an era of sharp partisan conflict over environmental issues, Lodge seems almost relieved to report that where invasives are concerned traditional enviro-political boundaries do not apply. “The full support that both the Clinton and the Bush administrations have given this issue reflects how serious it is.”
“He’s made some really important contributions in bringing the science of species invasions together with the policy for dealing with them,” says former Notre Dame colleague Steve Carpenter, a highly decorated lake ecologist now at the University of Wisconsin. “That’s not easy to do.”
Still, warns Lodge, “There is not enough being done on any level: local, state, federal or internationally.” New Zealand, Australia, South Africa and Norway are all more advanced. The American political system makes implementation of safeguards different and harder. “It will require collaboration of local communities, states and the federal government,” says Lodge. The federal government can’t—and shouldn’t—do it alone, but it does need to provide the coordination and start-up resources to states.
And while ecologists bring a special expertise to bear on the problem, Lodge is not asking for final say. “I want to tell people about how the world works, about what organisms have lived here in the past, and haven’t lived here, and what effects might occur if you introduced, for example, bighead carp into the Great Lakes. But once I’ve told people that bighead carp came from Asia and that they might cause great damage in the Great Lakes, it doesn’t follow immediately or inevitably that bighead carp shouldn’t be allowed into the Great Lakes.” Somehow, society must weigh the net effects. “That’s what our political system is all about. “
En route to UNDERC, Lodge detours to Boulder Junction, Wisconsin, the nearest town center. Housing is tight at UNDERC, so some students are renting a home next to the Flambeau River, where they’ve located another invader, the Chinese Mystery snail. How did a Chinese delicacy wind up in a wild Wisconsin river? Probably from the booming live food trade. “If you go into any major American city you can buy all kinds of things that are alive,” says Lodge. “It will blow your mind.” Riverside, he pulls a few off the dock pilings, but they’re small. Spying some larger specimens across the way, he strips off his shirt and wades in to collect the second course: escargot.
Back at his cabin, the edibles are deposited in the kitchen while the smaller crayfish are immediately placed in deep freeze in the lab. Once dead, they’ll be disposed of off-site. The Notre Dame facility, with 30 lakes behind lock and key, makes a perfect reference site for Lodge’s work. With access strictly controlled, the lakes are not likely to be invaded, and Lodge doesn’t want that to change.
After a few Internet searches on the preparation of snails, the crayfish are ready for the pot. Lodge’s crew—three graduate students and their summer assistants—begin to arrive, bearing bread, salad, Alfredo sauce and spaghetti. Soon bowls of steaming, lobster-red crayfish reach the table and body parts begin to fly. They’re on the small side, but once extricated, the kernels of white flesh are as succulent as their Maine and their Louisiana cousins, which Southern locals call crawfish.
The students are relaxed in the company of their boss and mentor, though a few remain suspicious of the main course; fewer sample the snails. It could be worse. While in Kenya to study the impacts of Louisiana crayfish, Lodge treated his Kenyan technicians to a crayfish lunch. “I thought it would be fun, but they refused to even take a bite,” he says, confirming another complication of invasives: One man’s trash is another man’s treasure. “The idea of eating crayfish was so repulsive to them, they couldn’t do it.”
Louisiana crayfish in Africa provide yet another wrinkle to the invasive tale. Brought in by British colonials, now they’re being explored as possible biological controls for the snails that harbor schistosomiasis. There are more than 200 million people with this devastating tropical disease; 10 percent die every year.
Despite the promise, Lodge’s work indicates there could be unintended consequences. East Africa’s Lake Victoria has already lost untold species to invasive—and ravenous—Nile perch. “There is so rich a biological heritage in Lake Victoria that we should put a high value on protecting it from yet another species,” says Lodge. “On the other hand, it’s awfully difficult to weigh those kinds of damages against the potential benefits of reducing disease.”
This tension is writ large on the American landscape. Of the 30,000 exotic plants, animals and microbes already in the United States, only a tiny percentage are considered invasive and harmful. Many more provide net economic benefits. In the absence of a comprehensive strategy or policy, thousands more enter every year without forethought or review.
“There are environmentalists that say we have to reduce the risk to zero, but I think this is neither a practical nor theoretical option,” says Lodge. It’s simply too expensive. As lead investigator on a $3 million National Science Foundation grant, Lodge is trying to refine a cost-benefit analysis to help simplify policy choices. For example, given a freshwater lake with a power plant drawing cooling water, what is a rational investment to prevent the spread of zebra mussels into the lake? Over five years, the answer is nothing; the likelihood of a damaging invasion is too small. But use a 25-year time horizon and it becomes rational to invest heavily in protection.
“Our political system, for all it’s unbelievable strengths, tends to lead people to take a short-term perspective,” argues Lodge. “One of the things I think ecologists and environmentalists often bring to the table is a long-term perspective.” Consider homeland security. A biological attack—anthrax or smallpox, perhaps—is really just a subset of the invasive species problem. Whether you’re talking about weaponized smallpox or zebra mussels, they all grow and spread governed by the same biological rules and processes.
“We’ve been suffering from biological damage from other nations for centuries, and increasingly so in recent decades,” notes Lodge. That’s why the Centers for Disease Control has the power of quarantine against threats like SARS and monkeypox, while agricultural authorities can burn entire groves to stamp out citrus canker. But protecting native ecosystems is just not on the radar. “We are suffering death by 1,000 nicks from invasions that happen every day, that are both intentional commercial activity and unintentional.”
As we invest heavily in homeland security, says Lodge, we should focus not only on the “risk to human health, but to things that pose a threat to our natural ecosystems as well, which we value in the long run just as highly. If you’re looking for packages the size of a dirty bomb, it should be equally easy to look for organisms, things that are not intentionally a threat or a weapon but, nonetheless, are likely to cause great damage.”
There is a certain calm that envelops many people on a northern lake, a sense of well-being, of life well-lived, a sneak peak at paradise. The sky reflected atop bottle green depths. The clean, enveloping water. Air scented with pine and a hint of fresh fish. A gentle chorus of birds and frogs and wind in the leaves.
This is what many would call a sense of place. By the end of your visit you’re thinking like a fish, a loon, an otter. Other landscapes provide different input, but the effect is the same.
Twenty years and 150 lakes later, Lodge sees the patterns and timing of invasions and senses another landscape slipping away. Only now he hopes his science can intervene. Though the pace of action at the federal level can be frustratingly slow, he believes a clear consensus is emerging. “Even industries that depend on the live organism trade are beginning to realize the extent of the problem,” he says.
“In the same way that there is a strong emotional, spiritual and cultural connection to historical buildings and urban parks, the plants and animals of the rural and wild landscape, especially those unique to an area, are very important,” says Lodge. “The beauty, the smell, the changes over the seasons are part of the connection to family, social traditions and God. Maintaining the existence of the local and regional flora and fauna is as important as the preservation of historic buildings. Seeing the Alabama woods I used to walk in as kid, for example, grown over with kudzu and Asian honeysuckles, and the lizards I used to catch replaced by lizards from other countries, is a blow to my identity.”
Lodge’s dire words continue: “The things we do now will determine what will happen, or the kind of ecosystems that we’ll leave our children and grandchildren,” he says; “Invasion is forever.”
Copyright 2005 by Erik Ness