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Lucy Irons


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Are you concerned about the spread of invasive species?

Invasive species are non-native species that have a negative impact on their introduced environment. Invasive species are a huge issue not only due to their environmental impacts, but their economic ones as well. According to the National Invasive Species Information Center, there are currently about 50,000 invasive species in the United States alone that cost over $138 billion annually to manage. invasive species have a number of distinctive traits, including A general diet, large amounts of genetic variation, the ability to survive in a wide range of climates, a continuous breeding season, and the production of many offspring every year. What role do these versatile organisms have in a world where many species and ecosystems potentially lack the diversity required to survive rapid changes in their environment? Is it possible that, in the face of global climate change and biodiversity loss, invasive species can contribute something positive to biological systems?

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  • Mar 16 2012: I live in Hawaii, where invasive species is almost an everyday topic. I've seen first hand that not all species were invasive at one point. Hawaii has an endemic hibiscus, among many other plants. Very little grows on fresh lava flows. Ferns and Ohia are the first things to grow. It is possible to have only native plants in an area, but humans have to leave that area alone. Humans, birds and the ocean are the great seed carriers. I live in one of Hawaii's last rainforests and when I look out into my yard, I see a variety of native, indigenous, endemic and invasive. The strawberry guava is one of the worst. Not only does it canopy and spread like fire, but it's leaves also add acid to the ground, so that nothing can grow in it's place. Hawaii has struggled for decades, if not centuries, to preserve the native flora/fauna. You can look at the history to see how things have been bio-controlled here with little success. Usually what ends up happening is, whatever thing you bring to control the invasive thing, becomes invasive itself (i.e. mongoose). Kipuka are a great example of endemics. There's a hau variety that lives only in one kipuka near Kilauea. So what do we do to keep the invasive species down? I think we should study these plant more and maybe we could find a use, then encourage exploitation in the areas where they're invasive, creating benefit out nuisance.
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      Mar 16 2012: I like your point about finding benefits of invasive species. I also agree that in a lot of situations, the best thing is for humans to leave well enough alone. However, as humans how often does that actually happen? For some reason we always feel the need to fuss with our environment.
    • Mar 17 2012: I enjoyed reading your post. Biological control is a popular method of curbing the growth of invasive species. Using a predator to target the invasive species is generally more preferable than using a pesticide or some other immediately destructive method of control. Pesticides affect other plants, species that eat the target plant, and they also contaminate the ground water and thus pose a threat to the entire ecosystem.

      However as you have indicated, introducing a predator has a huge drawback in that this predator will naturally have a bountiful food resource since the invasive species is so prevalent. The predator will experience a high rate of growth. Quite often it consumes other resources other than just the original invasive species. By these means, the predator which was intended to control the invasive species becomes an invasive species itself.

      If introducing a predator is the preferred method to control an invasive species, we should introduce a predator that is as species-specific as possible to the invasive species, in order to limit the damage and disruption it will have on the native species.
    • Mar 17 2012: I really like your idea that we should find a use for the invasive species, so that we can make it a resource rather than a problem. It would take research to see where it would benefit, but if you could find a use for an invasive plant or animal then you could reduce the population size and benefit our own population. That is a great suggestion versus other methods that might not be as effective.
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    Mar 15 2012: Are there any native species so to speak?
    Was the ecosystem ever stable, like in the Old Testament?
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      Mar 16 2012: "native species" are called endemic. There are many.
      Some even very local like the fish in the great African lakes: Victoria, Tanganyka and Malawi.
      Also among others Madagascar, Australia, New Guinea have their own species and evasive plants and animals are of great concern for those countries.
      In W. Africa you often find species of fish that are local to only a part of one river system, endemic to that area.
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        Mar 16 2012: informative
        But my point is that everything, at some point, has invaded an ecosystem, thrown everything off balance and caused massive extinction of something else.
        it's a jungle out there
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          Mar 16 2012: A good example, I think is cyanobacteria. As the first oxygen-creating species, it could have potentially destroyed everything. As oxygen levels rose, organisms struggled to survive in the new environment. However, without cyanobacteria, life as we know it would not exist. Oxygen breathing humans would not exist. The history of life on earth is littered with stories of upheaval and the subsequent quest to restore balance.
    • Mar 17 2012: Hi ya all! It is a total jungle out there. ( thanks Gerald ) We as humans, will be our, own down fall. We cannot learn from history , present, OR future. If there is a god, she or he, is laughing at us. :(
    • Mar 17 2012: This is a great question. What exactly is "native"? How long must a species exist in an environment to be deemed native to that area? Where do we set the baseline for determining what really "belongs" in an environment? I don't think there is any one answer that will satisfy all of these questions.
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        Mar 17 2012: Cuteness is involved as well, it seems. No one gives a damn about invisible natives.
  • Mar 17 2012: I think there are definitely possibilities of invasives that can have positive effects on their ecosystem, especially given some time for the ecosystem to adapt. If ecosystems are given time to adapt, it seems to me like eliminating them could create even more problems, and may be a waste of money to remove. A quote from an article in Penn State Science (http://science.psu.edu/news-and-events/2011-news/Carlo2-2011) sums up this idea well:

    "Nature is in a constant state of flux, always shifting and readjusting as new relationships form between species, and not all of these relationships are bad just because they are novel or created by humans...We need to be more careful about shooting first and asking questions later -- assuming that introduced species are inherently harmful. We should be asking: Are we responding to real threats to nature or to our cultural perception and scientific bias?"
    • Mar 17 2012: I think that if an introduced organism has a positive impact on its new location then it is very well may not be an invasive species. IN this case we would need to look at the actual definition of an invasive. Is it non-native? IN this case yes. Does it do harm to its introduced environment? If the answer is no then we need to define it has something else. The negative connotations carried with invasive species would not apply this is "positive" organism. And if in time the species and ecosystem adapt to one another then it can in no way be called an invasive species.
  • Mar 17 2012: I don't know if invasions will necessarily contribute to increased biodiversity. In many cases, invasive species can decrease the diversity of an environment because they either out-compete everything else or they alter the environment so much that other organisms can't live there anymore. If anything, I'd say that biological invasions have the potential to homogenize ecosystems around the world.

    I do think that introduced species are capable of driving evolution and speciation. And I'm sure that past invasions are responsible for the biodiversity we see today. In the past, however, invasions occurred at a vastly slower rate than the rate at which they occur today. This increased rate of introductions has been largely facilitated by human activities (e.g. shipping, travel, etc.). At the present rate of introductions, evolutionary adaptations cannot arise quickly enough for populations of native species to keep up with their rapidly changing environments.
  • Mar 17 2012: http://www.youtube.com/watch?v=t3ENUqV5-bw

    Not particularly relevant to the question at all, but as the description says, "just a [flippin] awesome animation".
  • Mar 17 2012: It has been argued throughout this thread whether or not invasive species are doing more harm then good? There are many great supporting claims for each side. Invasive species can be seen as contributing to the overall biro diversity of that community. They can also be seen in a negative light if they disrupt the natural 'native' life. Perhaps they are doing more harm then good...What would be the best way to eradicate them (if necessary at all..)?
    The options could include: genetically modified virus that would wipe out the population, a naturally occurring virus that would wipe them out, species specific predator, isolate the community so no dispersal or migration could happen, or propaganda.
    I was thinking that the first step in the efforts to get rid of any invasive species would be to give information to the local people of that area to give an awareness. I have heard that in Napa County, CA the glassy winged sharp shooter is decimating many vineyards. Many fliers and informational ads were circulating around the community advertising ways for farmers to control the pest. The efforts eventually payed off and there has been quite a reduction of the shooter. Educating people on the way invasive species travel, or hitch a ride, could force traveling regulations to be more strict for carrier ships. After educating the general public I think that if the plot of land where the invasive species was taking over, with negative consequences, should be isolated and controlled. If this area is too big then I would say to introduce a natural virus that would only harm specifically the invasive population. It is tough because each solution seems to come with its own repercussions. Is there one answer to this?
    • Mar 17 2012: I know this was a small part of your comment, but non-native species don't necessarily contribute to biodiversity. In many cases, the introduction of non-native species decreases biodiversity. If there is no predator (or other limiting factor) in the new environment to keep the population of the invasive species in check, it can quickly overrun an entire community and essentially create a monoculture. This can cause local extinctions of native species and could also alter the environment enough that re-establishment of these species is nearly impossible.

      As for eradication, I completely agree that education and fast action are the best route. If you know something about the biology of an invasive organism, it may be easier to control its spread. A great example of fast action within a community occurred in New Zealand, where an invasive tunicate was quickly overgrowing shipping vessels and hugely impacting the local mussel industry. The community worked very fast to eradicate the invader before spawning season, and were very successful. Here's a link to a report about this eradication: http://www.nzmfa.co.nz/assets/PannellCoutts07.pdf
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    Mar 17 2012: In relation to your last question, I think that it's completely possible for an invasive species to contribute both positively and negatively in the environment. Because somethings are changing rapidly, it might be possible for an invasive species to fill in an ecosystem service gap that is created by a species that can't adapt as quickly, especially if the invader is a strong competitor. What is hard about this type of situation is trying to determine if the negatives outweigh the positive contributions. I think it would take a great deal of time and study to determine that, and unfortunately, in that amount of time, it might then be too late to control the invasive.
    • Mar 17 2012: I agree. I think that trying to weigh out the benefits vs the bad contributions that an invasive species can be a time consuming period. Implementing goals, strategies, and actions can be even more time consuming. What is important though is prevention in the first place. If educating people to become more weary of what they are bringing with them when they travel, and how invasive species can affect our environment hopefully some of the species that have potential to invade, will not have the opportunity to.
    • Mar 17 2012: Education is an important aspect of combating invasive species. When the general public becomes aware of what an invasive species looks like and how it negatively affects the environment it is in then people will be more obliged to contact local officials who can deal with the invasive. But when people are unaware of an invasive that is where the real danger comes from, when an invasive unknowingly wrecks havoc on an ecosystem. So then what is the best method toward educating people?
  • Mar 16 2012: Change is always hard, and it is difficult for us to "let go" of certain species that we might be losing, but I think each case needs to be looked at individually. For example, it seems that zebra mussels can in fact be eliminated with the bacterial remedy that by all accounts seems not to harm the ecosystem in anyway. Other measures against invasives seem likely to cause more harm than good. So I guess I agree with both sides - I think sometimes it is in everyones best interest to try to remove the species if this can be done effectively and without negative impact, and sometimes we all just have to learn how to get along and adapt to the new situation, and that goes for other species that might be negatively impacted by that invasion.
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    Mar 16 2012: Invasive species are of great concern everywhere over the world.
    Life has developed and built ecosystems to benefit maximal from the local available energy.
    This happened over many millennia sometimes split up and divided by the movements of the earth.
    If plants or animals are introduced that aren't fit to sustain the local equilibrium the ecosystem will collapse.
    In Australia there's one island where up till today the complete original fauna still is present. They have a hard job to keep it that way.

    An example of the deliberate ruin of an ecosystem by ignorance.
  • Mar 16 2012: When I think about invasive species I think about a harmful species that has a huge negative effect on its ecosystem and surrounding ecosystems. This is true, but I also think that the degree of negativity of the invasive species needs to be consider in answering this question. An invasive species that does not kill everything it comes into contact with is going to be less of a threat and could potentially be a benefit when looking at the adaptation that is necessary with the overall loss of biodiversity and climate change in today's world. In this case we could let evolution run its course and only mediate when problems arise. On the other hand invasive species that has negative effects that would wipe out an entire ecosystem would not be beneficial to us and would definitely need to be eradicated. So overall, I think that to determine whether or not we should be concerned about an invasive species lies within the degree of detrimental effects that the invasive species has on the ecosystem.
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      Mar 16 2012: I totally agree that there are different degrees of invasiveness. An interesting question that I think is relevant both in biology and in global politics at the moment, is whether or not we, as humans, have the right or responsibility to "fix" things that we deem as problems with our environment? Is it about what's beneficial to US or about what's beneficial to the planet? Humans are special in that we can think outside of our own survival and try to look at what would make ecosystems better as a whole and sometimes I think we'll see that those two goals oppose each other.
      • Mar 17 2012: Here's a good example of humans attempting to "fix" something: http://www.youtube.com/watch?v=48_X6gA8S18
        Because the cane toad has already established and is hard to remove these folks have targeted one of the negative effects that it has and is trying to alleviate it. Some may say that they are unethically interfering with the quoll's behavioral evolution, but I believe it can actually be for the better because we have the capability to recognize if things are heading in a bad direction and we can "nudge" other species towards different evolutionary paths.
        • Mar 17 2012: Much can be learned in the case of the introduction of the cane toad. When researchers developed a plan to protect sugar cane plantations from cane beetles, they failed to look at seemingly obvious factors, such as where the biological range of the cane toad actually is. They implemented the plan thinking that the toad would specialize in the beetle on the sugar plantations without realizing soon enough that the habitat is unsuitable for amphibians. It was too hot and dry in the fields, and the cane toads preferred the shaded regions of the ecosystem. They effectively invaded a region of the landscape other than where they were meant to stay. What's more, their toxic bodies, as you have referenced, became devastating for the native populations of species that were ill-adapted to consuming the toads.

          The good news is that we are actually witnessing involuntary natural evolution in conjunction with human-induced adaptation. Not only are researchers catalyzing the adaptation of threatened species to avoid eating the cane toad, other species are learning on their own how to handle the toxin. Some bird species, including the black kite, learned to consume only the belly of adult toads, which do not contain the toxin. Certain species of aquatic frogs can consume the tadpoles of the cane toad before they develop the toxin glands.

          I agree with you that we should use our power to help "nudge" species in a direction that stabilizes their populations, but it is conditional. We should not interfere before we have a proper understanding of the ramifications of our experimentation. The cane toad implementation is an example of how interference can go wrong and how it can be righted.
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    Mar 16 2012: Invasive species are determined invasive and of concern based on the negative effects they cause on humans. Therefore, they have a negative connotation that is based on the way we perceive them. But we forget that habitats are constantly changing, having one species dominate over the others and that qualities of invasive species have driven evolution. It seems like the more our lives have become more structured and less nomadic, the more certain species become a threat to our budget and the biodiversity we associate to particular habitat. The more structured we become, the less adaptable to change and therefore the more susceptible to damage cause by invasive species. This issue is essentially one that we brought upon ourselves and are continuing to do so since we are most often the cause for introducing new species into an area. If we were removed from the situation, the introduction of non-natives species to an area would be much harder to. So now, there really is two things we could do, and that is to either attempt to completely remove all invasive or understand that they are not going anywhere and we need to adapt. We need to think of innovative ways we could deal them and perhaps use them to our benefit somehow ,such as by eating them in some cases. Or we could completely reconstruct the way we live, but that probably won't happen. My best idea is to prevent further human-dispersal of species to avoid all the negative effects that come with them.
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    Mar 16 2012: Yes we are the carriers for invasive species even today,alot of them get by our countries containment measures because it's too big a job to properly police/investigate/decontaminate every product being imported by our countries.i.e Harbour ports that stack containers,perfect hiding places for insect tourists.

    One only have to look at my country to know that it's us that has caused the damage.

    Rabbits are a major blowout species especially in an environment that has no natural predators to counter them.We tried a disease that brought their numbers down but it shot back up not long after,we only have ourselves to blame.
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    Mar 16 2012: Yes, humans seem to be invading everywhere.
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      Mar 16 2012: I've always considered humans as sort of the ultimate invasive species. Not only have we spread far from our original range, but we tend to destroy biodiversity and ecosystems as we go. It's a cynical view, but I believe there is some truth to it.
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        Mar 16 2012: totally agree.
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        Mar 16 2012: Aren't we as humans an invasive species? I know we don't meet the criteria as a one with short generations, but we make up for that in our ability to adapt through technology. We need to fuss with our environment in order to stay fit due to our long generations. While other species become more fit by evolutionary methods, we become more fit through fussing with the environment.
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    Mar 16 2012: Invasive species is a subject that I have come across a lot. Invasive species are localized to one area. what is invasive in one area may not in another. We think of rabbits as cute and cuddly, but in Australia, they are considered a vermin. This is because we have to negative effects from them, so it comes down to definition. to be invasive, you must be non-native and have negative effects. That being said, I find that invasives are a huge problem, but the only thing we can really do is destroy what they live in, unless preventative measures are used. But even preventative measures are hard to put in place. Thus, we need to just educate the whole population on the ramifications of invasives, so they won't track native species to non-native areas where they could become invasive.
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      Mar 16 2012: Why must we take preventative measures or destroy these invasive species? Isn't there a way to be passive or embrace these invasive species. Sure Cane Toads and Zebra Mussles are invading habitats right now, but this has happened over and over again throughout history, one species dominating another. The chances of another species invading Austrailia and killing all the cane toads is bound to happen, be it a virus/bacteria/bird etc. What would happen if we actively transported a bunch of species, wouldn't the ones that were most suitable for that particular environment thrive and those that weren't just die out. Perhaps its time we figure out how to utilize invasive species instead of holding on to the ones existing now.

      I found this site with some myth debunking:

      So we lose old Austrailian Toads and now we have cane toads. We lost mammoths and sabre tooth tigers and dinosaurs and Dodo birds, we're bound to lose more.
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        Mar 16 2012: We are bound to have loss, this is true, but within the last century it as been measured that the rate of extinction is much greater than that of the background or natural extinction rate. That is why some scientist are referring to this as the holocene, which is the next great extinction. And yes some species dominate others, but these cases of dominating species are not natural. they are human cause, and that is why they need to be fixed by humans, if at all possible. And ass for the utilization of invasives, that already happens just see the link below for that.


        There are many more articles and papers on this throughout the web.

        Also, I find that it is not the invasives that we hate, but moreover we hate the fact that we allow them to hitchhike via us humans. We try to eliminate them, because as i have said, it is our fault that the invasives are there.
        • Mar 17 2012: Clinton brings up a great point, that since we have become the dominant species of the planet, we have brought with us an unprecedented level of extinction. I agree with Rishi, that it is not that different from the extinction of many species, such as the mammoth and sabre tooth tiger, but that will soon include us if we are not careful. The distinction needs to be made when dealing with human-induced invasion.

          The Zebra Mussels will cause a change in the aquatic environment, as they have for the Great Lakes and associated rivers, which on its own (without putting human needs on the table) is not good or bad for the environment. The effect on the human environment, however, is potentially devastating. Since we are attempting to prolong our existence as a species indefinitely, we must understand that invasions like this one work against that.
      • Mar 17 2012: This sort of debate reminds me a lot of a movie by Kiyoshi Kurosawa entitled Charisma (http://en.wikipedia.org/wiki/Charisma_(film)), which portrays the conflicting views that humans tend to have toward nature. In it, the protagonist encounters a mysterious and toxic tree over which different parties are quarreling over. One man wants to preserve it, even if it means the death of all the rest of the trees. He wants to step back and let nature take its course. Another woman, a biologist, wants to remove the toxic tree as soon as possible before the rest of the trees become dead from it. She wants to protect the current forest.
        I think that both of these conflicting views equally value nature, but their differences stem from a difference in definition of nature. One view defines nature as this on-going and continuously changing process, while the other view defines it more as a certain point along the timeline of evolutionary history. In a sense these two perspectives are the same thing, only in different dimensions.
        Do you choose to define yourself as who you are this very instant, or as the culmination of all your experiences- past, present, and future?
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          Mar 17 2012: Zane,
          I have seen Charisma and I think you make a valid point. There are always conflicting views, especially in issues incorporating invasive species.
          In this situation, I would consider myself as someone who has accumulated my past experiences. It is difficult to predict the future, but I like to think that I am openminded enough to be prepared for what could happen.
          For Charisma, I believe the I would have wanted the tree removed as well. Even though it may have cultural and personal meaning to the main character. If it is hurting more than helping, I would want it gone. Cultural significance is important and I respect that, but from a biology perspective, there was nothing but hazard for that invasive tree.
        • Mar 17 2012: What a great example Zane! I think this such a good way to frame the two sides of the debate. Not only do we have different ways to define nature, but different perspectives as well. Of course we are going to naturally take the human perspective, but doesn't that tree have a right to be there also? Maybe the other trees in the forest would die initially, but perhaps those with some kind of resistance to the toxin would survive and repopulate that area of the forest. We fear the unknown consequences of our actions, but nature can also be surprisingly resilient, and is in constant flux - I think we need to have a little faith in mother nature!
      • Mar 17 2012: One argument for taking preventative measures is that certain invasive species have harsh economic ramifications. When the tansy ragwort was rampant in Oregon during the 1970s and 80s, farmers incurred annual losses of $ 4-5 million due to dead cattle, horses, and lost crops and pasture. This is just one example, there have been many other instances of invasive species causing economic hardship. Clearly, preventative measures need to be taken to prevent financial losses.

        But if we are not affected by an invasive species taking root in an environment and it only affects other species, should we spend the time and financial effort to solve this problem? This is an ethical issue - we have to decide whether we are morally responsible for the survival of endangered species.
  • Mar 15 2012: We are suffering, and I do not use the term lightly, under the invasion of stink bugs. They are doing enormous amounts of damage to our crops and our house. On a global scale however, aren't all species invasive at one point or another? Don't invasions drive evolution?
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      Mar 15 2012: This is a good point. What defines a native species? They have always been moving and migrating around the globe both with and without the help of humans. This spread of genetic information is incredibly useful and has been in the past. A question to think about is, are humans causing this phenomenon to occur too quickly? Are we moving species around faster than the ecosystems can adapt and recover? It's definitely interesting to consider.
      • Mar 16 2012: Lucy I think these are great questions! On some level I do agree with Sharon, all species are invasive at one point or another. I mean this is really a fundamental idea behind immigration, emigration, and migrations. A species will move around until they find an environment that is suitable and where they can be successful. However, they move around on their own time by their own means in a natural way. With the industrial revolution and other large developments in the world wide trade industry species are more easily moved from their original habitats to entirely different ones. By these means they could conceivably be moved whole new sides of the plant, and are forced to adjust and thus compete with the native species of that new environment. Is this avoidable at all? Is there any way to ensure that no species will hitch a ride on products that are sent around the world and land in a non native habitat?
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        Mar 16 2012: Defining a native species is certainly hard since it depends on when one sets the starting point. such as a plant is native to the Willamette Valley if it grew here prior early settlers bringing with them several European plants. But if we think before that, it is true that native species have been moving around and migrating but never as far as humans have been able to take them through boats and airplanes. Plants and animals do disperse but at a much slower rate, therefore altering ecosystems slowly and progressively, not like species that are considered invasive now.
        • Mar 16 2012: Most of the iconic plants associated with Hawaii, are not native to those islands.

          Humans have been moving plants around for centuries. Just ask Australians about the issues related to introducing a species to handle another problem with another human introduced species....

          Is it happening faster? Is it happening with more deleterious effect? Good questions. With climate change throwing all species a curve ball I suspect we'll be seeing many species moving pretty rapidly to locate more hospitable locales. I think the issue of invasives will be overwhelmed by species attempting to survive.
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      Mar 16 2012: There was a lady on one of our talkback shows years ago that was promoting earth worm revival and she stated that when you add fertilizer you are effectively adding cream to the pie, somewhat as farmers are growing maize for cows but if you promote more worms in the fields you will find less predation than the current system.