Yet quagga mussels aren’t likely to choke off Southern California’s water supply, or otherwise reprise the worst deeds of zebra mussels in the Great Lakes. Western managers can draw on the painful experience of their Midwestern counterparts to deal with mussels earlier and more aggressively. And some Western waters are too shallow, too warm, or otherwise unfriendly to quagga and zebra mussels. Cohen and his colleagues, for instance, found that at many sites in California, calcium levels are too low to support a viable population of zebra mussels, though whether these findings apply to quaggas is uncertain.
The fact remains, however, that mussels and infrastructure don’t mix. Mussel defense is an expensive, eternal, and — as California has already shown — occasionally dangerous business. On the Great Lakes, chemical feed lines for water intakes have cost anywhere from $50,000 for a small facility to upwards of $1 million. Such outlays, along with ongoing costs for treatment and monitoring, are inevitably passed on to consumers. The only way to keep the price down is to contain, and keep containing, quagga and zebra mussels.
Researcher David Lodge, observing the current crisis around Lake Mead from a safe distance, expects the Western quagga response will come to resemble a more rigorous version of the 100th Meridian Initiative, with a concerted campaign of public education and a prioritized system for boat inspections. (Inspections could employ legal as well as moral authority, since importation and transportation of nuisance species, including invasive mussels, is against the law in most states.) These humble tactics are credited with slowing the spread of zebra mussels in the Great Lakes, and so far, they’re the best tools on hand in the Colorado Basin and beyond.
“If you break the invasion down into components — if you look at the most likely ways for the mussel to move — then you can start to do something about it,” Lodge says. “Boaters, by and large, are people who care about the environment. You just have to give them an incentive to practice better boat hygiene.”
Of course, the 100th Meridian Initiative’s only success was in delay.
Just as the quagga began turning up in Lake Mead, biologists in the Great Lakes announced that the bloody red mysid, an omnivorous half-inch-long shrimp from the Baltic and Black seas, had become the 185th invasive species to take hold in the lakes. Exotic species are continually introduced into the Great Lakes through ships arriving via the St. Lawrence Seaway, with a new species establishing itself once or twice a year. Many are capable of hitching cross-continental rides.
Though some state and federal regulations aim to stem the flow of invaders into the Great Lakes and other U.S. waters, requiring incoming ships to exchange or treat their ballast water at sea, existing rules are notoriously inadequate. James Carlton, the first researcher to document and draw attention to ballast-water invasions, has described the global-transport network as “ecological roulette.”
Westerners “could be forgiven for thinking that they don’t need to care about invasions in the Great Lakes,” says Lodge, “but it’s clear now that the desert is no barrier, and the Great Plains are no barrier, at least not an insurmountable one. The invasions from the Great Lakes are not going to stop with quagga mussels, unless effective policies are put in place.”
The real problem, of course, is not these species themselves but modern human behavior, which makes it possible for mussels and shrimp to move around the planet as never before. Carlton has pointed out that the number of “vectors” carrying invasive aquatic species — ranging from ships to offshore rigs to the aquarium trade — has roughly doubled every 100 years. On the shores of Lake Mead, where modern vectors delivered the quagga mussel to an environment already profoundly altered by Hoover Dam, human ingenuity collided with itself.
“I suppose it’s a different situation if you’re dealing with a synthetic water body rather than one that’s been sitting there for x thousand years,” Paul Hebert says with a touch of acidity. “One could argue that you created a home for invasive species, so it’s only fair that the quagga mussel took advantage of it.”
And invasions may beget more invasions, some researchers say, by customizing the environment for other exotic species. Steve Yancho of Sleeping Bear Dunes National Lakeshore remembers surveying for piping plovers on one of Lake Michigan’s small islands. “We looked down, and in this bed of zebra mussel shells that was a foot or foot-and-a-half deep, there was a Canada thistle, a fairly aggressive invasive plant,” he says. “We pulled the thing out, and there was no part of the root that was actually touching the soil. One invasive species was entirely supporting another.”
So is our future filled with thistles, quagga mussels, cockroaches, and hordes of popcorn-fattened carp? Afloat on the rising global wave of invasions and extinctions, it’s easy to envision a monstrous, post-apocalyptic fauna, a homogenous cast capable of shredding nature’s diversity. Scientific wags call it the McBiota.
Julie Lockwood, a researcher who studies biological homogenization at Rutgers University in New Jersey, says that humans have certainly ratcheted up the rate of invasions and extinctions, but points out that not all invasive species have equal homogenizing powers. While some, like the zebra and quagga mussel, resemble global fast-food chains, others are more like regional franchises, still dominating, but on a smaller scale. “If we make an effort to contain the species that spread a long way, like the zebra and quagga mussels, nature does better than we might think,” she says.
Lockwood and her colleagues found that in California’s freshwater fisheries, for example, some remnants of regional diversity have — at least for the time being — survived a long history of intentional introductions and losses of native species. “We haven’t McDonaldized the whole place,” she says. “Some things do hang on in the face of invasions, partly because we want them to.” Habitat protection, pollution control, and other strategies, she notes, can still help fend off the McBiota: “The conservation work we do matters.”
At the close of the 100th Meridian meeting, the attendees set out for their various parks and states throughout the Colorado River Basin and beyond, newly charged with both containing the quagga and keeping its brethren at bay. They disperse, like so many propagules, into the currents of rush-hour traffic. As evening falls on the northbound freeway, a loaded boat trailer with Colorado plates climbs out of the glittering Las Vegas Valley with them, carrying its cargo upstream.
Michelle Nijhuis is High Country News' contributing editor.
This article was made possible with support from the William C. Kenney Watershed Protection Foundation and the Jay Kenney Foundation.
Congress has tried to regulate ballast water in ships in order to stop the spread of zebra mussels, but so far loopholes in the law and tussles over policy have made the effort ineffective.
Boaters, kayakers, anglers and other recreationists can help stop the spread of quagga mussels and other aquatic invasives by following a few simple rules.