The presence of non-native species in local ecosystems is becoming an increasingly common feature of a globalized world and a growing challenge to manage. While not all introduced species are harmful, some exotic species turn invasive and can cause significant damage to biodiversity, human health and the economy. In an essay published on June 8, 2011 in the journal Nature, Mark Davis and 18 other ecologists argue that the time is ripe to rethink management strategies for controlling introduced species and to re-prioritize intervention efforts onto those species that cause or are likely to cause the most harm.
In other words, they say, conservationists should assess organisms on environmental impact rather than on whether they are natives. Do you agree?
Exotic species are introduced into new environments by people through both intentional and unintentional pathways. Kudzu – nicknamed the “vine that ate the south” due to its extensive growth in the southeastern United States – is an example of an intentional introduction with unintended consequences.
Kudzu vine overtaking a bridge in Raleigh, North Carolina. Image credit: Suzie Tremmel
The vine was originally introduced to the U.S. from East Asia as an ornamental plant at the 1876 Centennial Exposition in Philadelphia, Pennsylvania and has since spread extensively across the landscape.
Unintentional species introductions occur during the transport of products across the globe. Often, exotic species are hidden away in the ballast water of ships, in wood packaging and in agricultural commodities. Many countries spend a great deal of time, effort and money to prevent these types of introductions through the use of regulations and inspection programs. Nobody is arguing that such prevention efforts aren’t worthwhile.
Zebra mussels, which can travel on trailered boats into new waterways, have caused millions of dollars in maintenance and removal costs in the Great Lakes and the Mississippi River drainage. Image Credit: USGS
The Nature essay is, unfortunately, not available without a fee or subscription. Too bad, because it’s an important issue, of concern to us all. What the authors of the essay are concerned about is the control of non-native species once they’ve established themselves in new environments. The ecologists point out that management problems can arise when control efforts for non-native species remain ineffective after many years of eradication efforts or when control efforts lack strong empirical data showing that non-native species are indeed harmful.
The ecologists acknowledge that it is largely impractical today to maintain ecosystems in pristine states composed entirely of native organisms.
The authors of the essay published in Nature aren’t recommending that conservationists abandon their efforts to manage introduced species that are causing serious problems, but they are pushing for greater use of scientific evidence in the demonstration of harm caused by non-native species and in the effectiveness of control measures.
Lead author Mark Davis is a Professor of Biology at Macalester College in Saint Paul, Minnesota, and is currently investigating what makes ecological communities vulnerable to invasions at the Cedar Creek Long-Term Ecological Research Station.
What do you think? Is the genie out of the bottle on non-native species? Do you agree with author Mark Davis and 18 other ecologists who write in Nature that that we should rethink management strategies for controlling them?
Is an all-out war against non-native species likely to happen? If it happens, is it likely to work?
How should the world approach this problem as the 21st century progresses?
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Show MoreThe invasive species are harmful for native systems and time and money should be invested to prevent these species from spreading and damaging systems that they are not native to. Strict rules for environmental obedience are necessary and good. Much more needs to be done to protect our planets and its biodiversity from the invasion of alien species. When non-native species from other ecosystems are introduced, they can upset that balance and bring harm to the established plants and animals, and the whole ecosystem. Non-native species come from somewhere else and they are not natural to the ecosystem they have been introduced to. They may be harmless and beneficial in their natural surroundings, but they can totally devastate…show more content…
Some native animals cannot leave. Without proper habitat and food supplies, they die. Great amount or damage can occur from an insect species that bores holes in trees, or weeds that take over, or zebra mussels that clog up water systems, like in the great lakes. There are many species that are not native to an area, which can be very dangerous and cause harm and even death to humans and ecosystems. A non-native species could be something that brings disease to an area or to people through introduced bacteria or viruses, or possibly a plant that would crossbreed with other plants and cause major changes to plant life and the organisms that feed on them. Many humans want to design their own ecosystems to fit their needs. They bring in ornamental flowering trees, non-native fish, specialty seeds, and unusual animals. This can wreak havoc on the natural species and the established habitat. Invasive species may be as harmless looking as green plants or a frog. They don't have to be vicious looking to bring harm to an area. They may even be attractive to look at. This could have a detrimental effect on native species if bees or other pollinators preferred the flowering displays of the invasive species to the native species. Not all non-native species are invasive and harmful. But many can completely take over and entirely change whole established ecosystems.
Many non-native species have been transported in the ballast water of ships and