Several years ago, I wrote a monthly eco-travel column called “Green Footsteps” for The Ecotourism Observer, a now-defunct e-zine operated by The International Ecotourism Society. Topics ranged from biosphere reserves to adventure travel for women.
Lately, I’ve been preparing these articles for my travel website, and I recently discovered one that was written in early 2002 and never published. As the subtitle indicated, it was intended to share “things everyone should know about transporting alien species between regions.”
Since I had so much fun researching it – and never got the chance to post it – I thought I’d share it with you now. Let me know what you think (and bear in mind that the information might be a little out-of-date)!
Do you recall that final heart-wrenching scene between E.T., the Extra-Terrestrial, and the hapless family who loved him? When I was younger, their tearful farewell made me weep like a sprinkler, but upon a more recent viewing, I couldn’t help but wonder: What exactly does that little girl think she’s doing, offering an earthly flower to a gullible member of an alien race? Call me an incorrigible ecotourist, but imagine the ecological repercussions of such a gift.
It’s tragic enough that, just by spending several days with a few well-meaning Earthlings, tromping through the unhygienic forest around their suburban neighborhood, and exposing himself to intrusive government scientists, E.T. could be unknowingly transporting any number of germs back home. In fact, unless he’s planned to submerge his entire body into a vat of bleach during his ascent to the mother ship, some damage will undoubtedly result anyway. But, even worse, when he chooses to accept Gertie’s yellow geraniums with spindly open arms, despite any microscopic spores or bacteria hidden among the petals, he could be subjecting his planet to a lethal foreign entity, which could very well decimate his entire species.
Scoff if you will, but oftentimes, the introduction of even the smallest rodent, fish, plant, insect, microbe, or other exotic organism into a foreign ecosystem can have devastating consequences for native inhabitants.
For instance, consider the effect that Formosan termites have had in the United States. Arriving accidentally via American ships returning from the Pacific during World War II, these super-termites have spread so furiously that they’ve now caused millions of dollars in damage, repairs, and pest control throughout the historic French Quarter of New Orleans. Sadly, that’s only one of countless alien organisms currently plaguing America’s agricultural industry, national parks, and fragile hinterlands.
Beware the exotics
Such aliens, also known as exotics, nonnatives, or invasives, are an extreme problem throughout the world. Global trade and travel have helped to spread these nonnative organisms at an incredible rate in recent years.
According to Frank McDonough, a botanical information consultant at the Arboretum of Los Angeles County, invasives “present a control issue in areas where they’re not wanted.” Without natural enemies in their new habitats, exotics have quickly proliferated, threatening or destroying countless established species. Once ensconced in a virgin territory, they are usually free to prey on or hybridize with native populations, pollute food supplies, degrade native habitats, and introduce fatal pathogens. They can also damage crops, increase pesticide use, and contaminate drinking water supplies.
This “bioinvasion” is one of the most significant detriments to native biodiversity, second only to habitat loss, and can ultimately alter the species composition of an entire ecosystem. According to David Pimentel, an ecologist at Cornell University, invasives have contributed to the decline of 42% of America’s endangered species and caused more than $137 billion worth of damage to crops, cities, and wild areas.
By their very definition, alien species are those that have evolved elsewhere and migrated to a region unaccustomed to their exotic needs. Although some insects, plants, and other pests have spread from region to region by wind, water, or birds, many potentially harmful organisms, from parasites to weeds, have reached U.S. coasts and inland regions by human error, either accidental or deliberate.
Most unwanted alien species, like Formosan termites, have invaded America as stowaways within ships, trucks, trains, and airplanes from other countries or regions. Other unintentional introductions have been transported by unknowing recreationists, travelers, and consumers of exotic pets and horticulture. Anglers have transferred parasites from shoreline mud to healthy waters via infected boots, boats, trailers, and equipment. Globetrotters have dragged home virulent insects and spores from foreign destinations via their luggage and clothing. Families have released unwanted goldfish, cats, and other pets into the wilderness, where they’ve spread harmful microorganisms or mated with native species. Homeowners have used water hyacinths, Japanese honeysuckle, and English ivy to ornament their gardens, despite their tendency to proliferate and suffocate other flora.
Several of America’s most troublesome alien species have been deliberately transplanted to provide sustenance or stimulate the economy. For instance, the Polynesians and Europeans who settled in the Hawaiian Islands carted ashore many exotic vegetables and animals from their homelands. Many of these introduced pigs, boars, cats, and mongooses eventually escaped or were released into the jungle, where they’ve spread deadly mosquitoes, cleared pathways for exotic plants, and preyed upon fragile mints, orchids, ferns, petrels, and nene geese.
To sustain certain U.S. industries, wealthy landowners and fur entrepreneurs imported Indian peacocks and Argentinean nutria during the late 1800s. Peacocks, prized for their ornamental feathers, now run amuck throughout countless zoos and sanctuaries, uprooting or smothering fledgling plants. Nutria, whose low-quality fur proved too expensive to produce, soon spread to southern marshes, where they’ve devoured fragile flora and removed critical habitat for many birds, shrimp, crabs, oysters, and fishes.
Of course, not all introductions are dangerous. Without such exotics as honeybees, kiwi fruit, soybeans, and tulips, American consumers might still be limited to the several dozen crops that existed prior to 1492. Still, no matter the advantages of certain exotic species, all such aliens can affect the present balance of nature, often in negative ways.
An alien invasion
When Yellowstone’s endangered grizzly bears emerge from hibernation in late spring, their first priority is to find a hearty meal. To replenish energy supplies exhausted during the winter months, approximately one-fifth of the park’s grizzlies head for the shallow tributaries of Yellowstone Lake, prime spots for Yellowstone’s native cutthroat trout, whose spawning season usually begins just as grizzlies emerge from hibernation. Grizzlies aren’t the only ones who benefit from such crowded streams. Bald eagles, river otters, black bears, coyotes, pelicans, ospreys, mink, and numerous waterfowl have also used cutthroat as an energy-rich food source.
Trouble arose, however, in 1994, when an angler presented park officials with a large nonnative lake trout, which he claimed to have reeled in from Yellowstone Lake. Ecologists were concerned, aware that lake trout are voracious predators of the cutthroat and, therefore, a threat to the park’s associated food chain. After subsequent investigations, officials surmised that an angler had illegally introduced the nonnative lake trout to Yellowstone Lake three to five decades earlier, a despicable deed that Tony Jewett, the Yellowstone Regional Director for the National Parks Conservation Association, calls “a classic, dark-of-the-night act by an uncaring individual.”
Jewett laments the ferociousness with which the introduced lake trout have devoured the native cutthroat, apparently rather easy prey for the invaders. “It was like dumping a starving man,” he says, “into an acre of apple pies.”
Still, as lake trout prefer deeper, colder waters during the summer-only fishing season, it’s plain to see how they escaped notice from anglers and park monitors for so long. If left uncontrolled, lake trout could come to dominate Yellowstone Lake. Given that they spawn in deeper water, they would be unavailable as a food source to most of the park’s wildlife, especially grizzlies that have come to depend upon cutthroat trout for post-hibernation sustenance.
Although Jewett admits that, given the lake’s vast size and the park’s limited funds, “it would be biologically incredibly challenging to eliminate all lake trout,” officials have done an admirable job of restraining the population. By imbedding radio transmitters on captured lake trout, officials have been able to track them to several spawning beds, where they’ve used industrial-strength gill nets to capture thousands of them. In addition, the park has opened fishing season earlier every year, when lake trout are in shallow streams and more vulnerable to angling efforts. As the lake trout population continues to grow, the park may be facing an expensive, never-ending program of species control, without which the country’s most viable population of cutthroat could disappear.
Despite this threat, the U.S. Fish and Wildlife Service recently decided not to list the subspecies as threatened under the Endangered Species Act, claiming that viable stocks remain widely distributed throughout the cutthroat’s historic range. So, park visitors are needed to protect Yellowstone’s dwindling cutthroat population by catching and keeping lake trout whenever possible. Otherwise, the loss of cutthroat trout, along with threatened whitebark pine trees, Army cutworm moths, and bison, also staples for grizzlies, could drive these sacred bears in search of other natural foods, which might lead them closer to humans and, therefore, closer to death.
An ounce of prevention
Even harmful invasive species can be advantageous for the environment. Peacocks, for instance, hinder pesky insect populations, while smothering vines can attract eye-pleasing butterflies. Such benefits make perfect sense to McDonough, who dislikes the word “nonnative.” According to him, every plant, animal, and insect is native to Earth and might, even without mankind’s help, travel from its common home to another region. When, however, such exotic migration happens faster than it might naturally occur, Americans’ health, homes, and natural heritage are often severely crippled.
“When pests travel over a land bridge,” McDonough explains, “they tend to bring their parasites with them.” The problem, then, may not be the invasive species themselves but rather that their unexpected arrival in an area previously devoid of them tends to give said habitat little time to adapt to the new competitor. Melaleuca trees, for example, may be prized in their native Australia, but in the Florida Everglades, where they were introduced in the 1930s, they have become a severe detriment, having evolved into immense forests that eliminate any nearby native vegetation.
Once an exotic species arrives, multiplies, and settles into a new ecosystem, ecologists must often utilize extreme solutions to eliminate the problems that arise. As with cancer cells in a human body, the complete removal of an invasive organism may only be feasible in the early stages or in a restricted area. In larger, more problematic domains, such as Hawaiian jungles and Florida marshes, biologists merely hope to contain each “bioinvasion” with human labor, pesticides, natural enemies, and environmental manipulation.
In Hawaii Volcanoes National Park, rangers must simply trap feral cats and pigs, an expensive labor-intensive method of control. In the Everglades, biologists have struggled to fight the melaleuca with herbicides, managed fires, and melaleuca snout beetles. Unfortunately, they’ve discovered that trees can become resistant to herbicides, fires can actually spread the seeds, and released insects can attack non-target organisms.
Because nonnative species don’t recognize regional borders, the key to limiting the harmful impacts of invasives is to prevent them from becoming established in the first place. Since most exotic species don’t pose a threat until years after they’ve been introduced, it’s crucial for humans to pursue activities that guard America’s distinct lands and waters from such exotic critters.
“This is one of those major environmental issues,” says Ann Bartuska, Executive Director of the Nature Conservancy’s Invasive Species Initiative, “where individuals can contribute to the solution.”
As voters, we can support legislation like the National Aquatic Invasive Species Act and push countries to regulate troublesome imports, inspect airplanes and trucks for unwanted stowaways, and force ships to release their contaminated ballast water into the open seas instead of virgin ports.
As consumers, we should be bold enough to ask questions and utilize such knowledge accordingly. Before sprucing up our gardens with certain ornamental plants, we should find out if they’re indigenous or alien. Bartuska suggests that we question nurseries about the origin of such species and the potential effects of growing them in a foreign region. She also blames the proliferation of invasive plants on our ability to purchase such exotics through the Internet and advises consumers to thoroughly research nonnative flora before inviting ornamentals like English ivy and water hyacinths to flourish where they’re not wanted.
As pet owners, we should avoid bringing exotic animals, including fish, birds, and reptiles, into a nonnative environment. If we already own pets, from cats to iguanas, we should never release them into the wild, no matter the reason. “I live in a college town,” Bartuska laments. “People are throwing out animals all the time.” She acknowledges that people have a tendency to free pets when they’ve become boring or unmanageable. As an alternative to releasing domesticated animals into fragile jungles, deserts, woodlands, and waterways, she proposes that communities create pet recovery programs instead.
As recreationists, we need to be aware of our own practices as well as those of others. Jewett and Bartuska concur that, whether we hike, fish, or hunt, we should inspect our boots, our clothing, and our boats for unwanted seeds, spores, insects, and weeds whenever we travel between geographically isolated areas. We should also note any hikers, anglers, or hunters who may be participating in a "bioinvasion," such as the angler who dumped a few “harmless” lake trout into Yellowstone Lake. “Anybody who witnesses what is basically a criminal act should report it,” Jewett advises. “Such activities can knock normal processes out of whack.”
As travelers, we must take care not to bring any nonnative species along for the ride, whether traveling home from an exotic island or exploring a national park just across the state line. For globetrotters, this may mean, as Pimentel suggests, first checking that any exotic animals or plants acquired in other countries have been approved by the United States Department of Agriculture or other appropriate agency. It could also mean checking our clothing, luggage, shoes, and tires for any unwanted seeds, spores, or insects before arriving in a new region.
Otherwise, native plants, animals, and ecosystems may feel the effects of our visits, long after our global treks or family jaunts have become distant memories. If only E.T. had listened to such sage advice and left the seemingly innocuous geraniums in Gertie’s capable hands, his planet just might have been spared.
4 hours ago