Recently, in a post titled “Ecologists: Time to End Invasive-Species Persecution”, Brandon Keim discussed a comment published in Nature which argued that the ecological community unfairly vilifies the various plants and animals we’ve transported around the globe. In some sense, the authors are right, at least as far as saying that not all alien species should be considered bad or needing removal.
Straight from the beginning, though, the authors attack a dichotomy that doesn’t exist. They write that a “native-versus-alien species dichotomy” is counterproductive, and that new, pragmatic approaches are needed. This makes it sound like scientists and managers label every plant or animal as A or B, and those in A are allowed to stay and those in B are eradicated. To an ecologist, though, there is no “dichotomy” – there are a range of labels that apply to a variety of situations. Specifically, there is already a strong distinction between invasive species and introduced, non-native or alien species – not to mention game species, fisheries species, etc.
I don’t know of a single removal program that seeks to eradicate every species in an area that wasn’t there 100 years ago. Removal programs don’t target all “non-natives” – they target invasives.
Invasive species get their own category, as well they should. They are specifically defined by the US government as “alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health.” Almost half of the threatened and endangered species are at risk due to the impacts of invasive species. In the US alone, invasive species cause an estimated $140 billion dollars in environmental damages and losses every year1.
Take the species I study: lionfish (Pterois volitans and P. miles). Lionfish were first sighted in the Atlantic in the late 1990s. In the past decade, they have become ubiquitous from Brazil to New York. They’re a classic invasive species: they grow quickly, breed year round, have no natural predators or diseases in their invasive range, and they are causing serious ecological damage. Studies have found they reduce the recruitment of larval fishes by 79% on average2, and they are causing a shift from coral dominated to algal dominated ecosystems3. The lionfish hardly stand alone. Hundreds of species from rats and mice to cane toads cause serious damage to ecosystems on a daily basis.
So do we over-vilify invasive species? No, we don’t.
The debate about invasive species really hits home in Hawaii, where 25% (maybe more) of the local flora and fauna aren’t just native, they’re endemic, which means they are found nowhere else in the world. It’s estimated that somewhere around 25 new species are introduced to Hawaii every year, but thankfully, most of these do not become invasive. Indeed, of the 13,000 or so species of plants that have been introduced to Hawaii, only about 1% are considered invasive. Those that are deserve the title and the removal efforts that tend to go with it. When invasive species take over natural habitats in Hawaii, they very directly and quickly drive species towards extinction. Not surprisingly, Hawaii has a number of invasive species removal programs targeting species that are or might be a problem.
I couldn’t believe the authors chose to picture Miconia (Miconia calvescens) removal in Hawaii as their lead image, especially since they then didn’t even bother to talk about it. Yes, a lot of effort is spent preventing the spread of Miconia in Hawaii, but it’s for damn good reason – all Hawaiian biologists and managers need to do is take a look at Tahiti, where it’s referred to as “green cancer”. A single Miconia was introduced to Tahiti in 1937. Within a half a century, the plant took over. By the 1990s, the plant had spread to 70% of the island’s forested areas, over a third of which were near monotypic, meaning the Miconia had out-competed and overrun all the other native species of trees4.
On Oahu, Miconia has not had that kind of impact because we have actively prevented it. If we were to stop these removal efforts, there is little doubt that Miconia would spread. One study estimated that it would take less than a century for Micona to take over Oahu like is has Tahiti5. That study also estimated what would happen if we stopped control efforts for the next 40 years; the cost of doing nothing, based on loss of native habitat and species, changes in watershed properties, and other ecosystem damages would be $627 million.
This is the species that Davis and his colleagues chose as the front image for saying we unnecessarily persecute non-native species?
But, of course, the authors don’t talk about Miconia, or any of the removal programs in Hawaii. They instead cherry-pick their examples, cite their own work, and ignore the vast majority of the science from the past ten years which supports invasive species management.
I wouldn’t be so bothered by this short essay, except that more than ever, management programs need to be supported. If only the authors’ claim that there is “a pervasive bias against alien species that has been embraced by the public, conservationists, land managers and policy-makers” were true. But sadly, many politicians and people just don’t care. Just earlier today, my grandfather was watching a Fox News segment called “The Money Hole“, in which John Stossel started ranting and raving about all the ways in which the US wastes tax payer money. One of his examples? The $500,000 spent on removing brown tree snakes from Guam – one of the nastiest invasive species around, responsible for the extinction of ten out of the twelve native bird species that once lived there as well as a slew of other damages.
I’m actually shocked this paper was published by Nature. I’m even more shocked such an essay wasn’t peer-reviewed and the authors were paid for it. Of course, I generally would find it hard to trust an essay where the vast majority of the cited papers are written by the coauthors, and those that aren’t are outdated by a decade. How can they deride the management plans currently in use when they don’t actually evaluate the current efforts?
By dishing out blanket criticisms towards all invasive management programs, the authors provide fuel to the fire of those who attack environmental work on a daily basis. Conservation programs and scientific agencies which study the practicality, necessity, and effectiveness of them are already first on the chopping block when budgets are cut. They’re struggling for funding in these harsh economic times, and articles like this one only seek to unfairly undermine their credibility when they need it most.
Comment in Question: Davis, M., Chew, M., Hobbs, R., Lugo, A., Ewel, J., Vermeij, G., Brown, J., Rosenzweig, M., Gardener, M., Carroll, S., Thompson, K., Pickett, S., Stromberg, J., Tredici, P., Suding, K., Ehrenfeld, J., Philip Grime, J., Mascaro, J., & Briggs, J. (2011). Don’t judge species on their origins Nature, 474 (7350), 153-154 DOI: 10.1038/474153a
1. PIMENTEL, D., ZUNIGA, R., & MORRISON, D. (2004). Update on the environmental and economic costs associated with alien-invasive species in the United States Ecological Economics DOI: 10.1016/j.ecolecon.2004.10.002
2.Albins, M., & Hixon, M. (2008). Invasive Indo-Pacific lionfish Pterois volitans reduce recruitment of Atlantic coral-reef fishes Marine Ecology Progress Series, 367, 233-238 DOI: 10.3354/meps07620
3. Lesser, M., & Slattery, M. (2011). Phase shift to algal dominated communities at mesophotic depths associated with lionfish (Pterois volitans) invasion on a Bahamian coral reef Biological Invasions DOI: 10.1007/s10530-011-0005-z
4. Meyer, J., & Florence, J. (1996). Tahiti’s native flora endangered by the invasion of Miconia calvescens DC. (Melastomataceae) Journal of Biogeography, 23 (6), 775-781 DOI: 10.1111/j.1365-2699.1996.tb00038.x
5. Kimberly M. Burnett, Brooks A Kaiser, & James Roumasset (2007). Invasive Species Control over Space and Time: Miconia calvescens on Oahu, Hawaii Journal of Agricultural and Applied Economics,, 39