invasive species management

Invasive species denialism: what is it, and what can we do about it?

Even when there is agreement on the impacts of invasive species on ecosystems, some stakeholders nevertheless deny the need for, or benefit of managing invasive species.

Guest blog post by Noelle G. Stratton, Nicholas E. Mandrak, and Nicole Klenk

Invasive species denialism (ISD) is a hot topic in recent invasion ecology discourse. Many of us are familiar with the concept of science denialism, particularly during recent discussions about climate change and the ongoing COVID-19 pandemic. Essentially, a person who exhibits science denialism is skeptical of, or refuses to believe, the scientific facts about a topic. Much of the discussion about ISD has focused on characterising it as a form of science denialism. However, while science denialism may be one form of ISD, it is not the only one.

Understanding the different forms of ISD is an important step in learning more about what drives ISD positions, and how those positions can be overcome to improve invasive species management. Recently, researchers at the University of Toronto outlined these ISD forms in a new paper in NeoBiota. While these framings are not the only ways to characterize invasive species denialism, they demonstrate that there are multiple framings to the ways that people deny the imperative to manage all invasive species as prescribed by early detection and rapid response.

So, what are the forms of ISD?

Venn diagram of the three forms of invasive species based on interviews and focus groups with invasive species community members in the Great Lakes region, including interested publics and decision-makers: 1) Invasive species denialism; 2) invasive species cynicism; and 3) invasive species nihilism. Each has different motivations and ways of talking about invasive species. Notably, all forms include an opposition to invasive species engagement or management efforts.

Invasive species denialism is the form that will typically come to mind when you picture a “science denialist”. Someone who does not believe in invasive species, or says that the existing scientific literature is all wrong, would fall within this framing. However, it is more complex than that. Invasive species practitioners also identified some of those who believed in invasive species and supported their management under this framing.

For example, folks who wanted management to happen immediately, be 100% effective, or have no risks to them or the environment whatsoever, were considered another form of denialist. This is because while these people supported invasive species management, they were still opposed to certain management efforts due to a lack of understanding of the science behind that management. Similarly, people who agree invasive species are a problem but say “this isn’t my problem, and I shouldn’t have to do anything about it” when shown evidence otherwise were also framed as denialists, as it again indicated a denial, or at least a lack of understanding of the scientific facts.

Invasive species cynicism is the form where someone may well understand what invasive species are and the science behind their management. However, they may still oppose management because they believe it will harm them in some way.

For example, someone who does not want to have to check and clean their boat to prevent an invasive species spread because it takes too much time would be categorized as an invasive species cynic. As well, someone who does not want to cooperate with management efforts because they personally like a particular invasive species and would like it to persist, despite knowing its potential for harms to the ecosystem or economy, is also an invasive species cynic. From these examples, it should be clear that this form of ISD is quite different from what we would think of as a “science denialist”. They understand the science, but it just does not motivate their beliefs or behaviour on this topic.

*This research was also recently presented at the* *International Conference on Aquatic Invasive Species* *by co-author Noelle G. Stratton. Invasive species nihilism, in particular, prompted discussion both in-person and on social media.*

Invasive species nihilism is the form that does not appear to take into account the science behind invasive species or their management at all. Rather, it revolves around the idea that invasive species research, management, or engagement are essentially a waste of time. The efforts were pointless and the results useless. This framing also differed from the other two forms in that the folks who expressed these beliefs often directly approached invasive species practitioners during the course of their work to inform them that their job was meaningless and to ask them why they bothered. This type of framing has the greatest potential to impact invasive species researchers and practitioners personally, and it is potentially the most difficult form of denialism to surmount during engagement and management efforts.

How can invasive species denialism impact management efforts?

ISD has the potential to hinder management efforts in a few different ways. Invasive species denialists may slow down decision-making by stalling or halting discussions with other stakeholders. In some cases, invasive species cynics have taken direct action to interfere with the implementation of policies that would aid with management efforts. Invasive species nihilism could make some stakeholders less likely to engage with managers because they have come to believe that management is pointless, and managers themselves may endure the stress of hearing that their work is not of value to people with this perspective. The effects that ISD may have on management are varied and depend largely on the type of framing of ISD being used. Similarly, the way that we respond to someone that we believe to be an invasive species denialist should be informed by the framing of ISD they are using.

“An understanding of these framings is also vital to respond to instances of ISD appropriately. Whether we are being confronted with anti-science contrarianism, environmental cynicism, or outbursts of nihilism, should inform our responses and our strategies to counter these positions.” (Stratton et al. 2022)

The framings of ISD explored in this research suggest that a diversity of interpretations of species movements, and value judgments about their impacts and the need for management, exist. This has the potential to problematize reductionist claims that all critiques of invasive species management are simply a denial of scientific facts. These results provide evidence that even when there is agreement on the impacts of invasive species on ecosystems, some stakeholders nevertheless deny the need for, or benefit of managing invasive species. This study further contributes to ongoing scholarly and practitioner conversations about the normative assumptions of invasive species biology and their implications for invasive species management and governance.

Research article:

Stratton NG, Mandrak NE, Klenk N (2022) From anti-science to environmental nihilism: the Fata Morgana of invasive species denialism. NeoBiota 75: 39-56. https://doi.org/10.3897/neobiota.75.90631

Image credits: diagram by NG Stratton; comic panels by NG Stratton, via material from Flickr (ChrisA1995, CC BY 2.0; Mike, CC BY-NC-SA 2.0; the-difference CC BY-NC-SA 2.0) and Studio Alternativi (Esetefania Quevedo).

Naturalists can mediate silent plankton invasions

Plankton can easily spread between water bodies on hydrobiological instruments if naturalists use inadequate biosecurity treatments in their work.

Homo sapiens is not only a great (perhaps the best) candidate for the world’s most invasive species award. Humans, due to their actions and technological wonders, are also at the forefront of good vectors for organismal dispersion. Can we break this inglorious streak?

“Because humans will continue to interact with terrestrial and aquatic environments, it is impossible to stop the human-aided dispersal of organisms completely. The best we can do is minimise the risk of human-mediated organism dispersal events by implementing adequate biosecurity methods in our activity” explains Dr Wejnerowski from Adam Mickiewicz University (Poland).

Plankton sampling using net. Photo by Sandra Wejnerowska

“We should be aware that all our activities can affect biodiversity, and adequate biosecurity treatments should be applied whenever the risk of inadvertent spreading of organisms is non-zero” adds Dr Marcin Krzysztof Dziuba from the University of Michigan (United States of America).

Recently, a team of researchers from Adam Mickiewicz University, Istanbul University (Turkey), Åbo Akademi University (Finland), and the University of Michigan empirically proved that plankton net – a basic hydrobiological instrument of almost every aquatic scientist and water manager – is a good vector for the dispersal of various phyto- and zooplankton taxa, including species of high invasive potential. Nuisance, bloom-forming, also toxic filamentous cyanobacteria are efficient hitch-hikers, and they are able to successfully compete with native residents in the new environment.

Instructions for US citizens to avoid spreading invasive species during lake recreation. Photo by Marcin Krzysztof Dziuba

Apart from identifying hitch-hiking plankton on the net and its fate in the new environment, the paper they published in the journal NeoBiota also describes the most commonly used biosecurity treatments that naturalists worldwide use to prevent plankton spread between water bodies via the net.

Their findings sound disturbing: naturalists use inadequate or questionable biosecurity treatments. As revealed by the survey data, only 9% of plankton samplers clean plankton nets using disinfectant liquids after sampling, while a majority of people either rinse the net with distilled or tap water, immerse the net with an open outflow in the water body and let it dry, or do not care about the cleanness of the net after sampling at all.

Exemplary photos of some phyto- (A – Limnothrix redekei, B – Planktothrix agardhii, C – Pseudanabaena limnetica, D – Melosira varians, E – Desmodesmus armatus, F – Asterionella formosa, G – Tetradesmus obliquus) and zooplankton ( H – Keratella cochlearis f. typica) hitch-hikers on the plankton net. Micrograph I shows the plankton biomass on the surface of the plankton net after immersing the net with an open outflow in the water body (inadequate biosecurity treatment). Photos by Tumer Orhun Aykut and Łukasz Wejnerowski. Identification of organisms by Aleksandra Pełechata and Marcin Krzysztof Dziuba.

“Indeed, the reality presented in the paper is unsettling. It worries me when I think of how often I have accidentally facilitated dispersion of nuisance plankton and how much I contributed to the invasion of plankton taxa into new water bodies when using inappropriate biosecurity treatments in my fieldwork,” admits Dr Wejnerowski, and adds: “We do not mean to reinvent the wheel; the problem of aquatic organism dispersal through hydrobiological instruments is already known. For years, it was neglected despite some recalls from the scientific community. It comes back like a bad penny because it needs a complex solution from the society of aquatic naturalists. It should happen. After all, naturalists are a human line of defence, protection and rescue for nature.”

Research article:

Wejnerowski Ł, Aykut TO, Pełechata A, Rybak M, Dulić T, Meriluoto J, Dziuba MK (2022) Plankton hitch-hikers on naturalists’ instruments as silent intruders of aquatic ecosystems: current risks and possible prevention. NeoBiota 73: 193-219. https://doi.org/10.3897/neobiota.73.82636

Invasive alien species? Isn’t there an app for that?

Scientists review 41 invasive species reporting apps and provide recommendations for future development.

Invasive alien species (IAS) are a leading contributor to biodiversity loss, and they cause annual economic damage in the order of hundreds of billions of US dollars in each of many countries around the world. Smartphone apps are one relatively new tool that could help monitor, predict, and ideally prevent their spread. But are they living up to their full potential?

A team of researchers from the University of Montana, the Flathead Lake Biological Station and the University of Georgia River Basin Center tried to answer that in a recent research paper in the open access, peer-reviewed journal NeoBiota. Going through nearly 500 peer-reviewed articles, they identified the key features of the perfect IAS reporting app and then rated all known English-language IAS reporting apps available to North America users against this ideal.

Smartphone apps have the potential to be powerful reporting tools. Citizen scientists the world around have made major contributions to the reporting of biodiversity using apps like iNaturalist and eBird. But apps for reporting invasive species never reached that level of popularity; Howard and his team investigated why.

User uptake and retention are just as important as collecting data. Howard and colleagues found that apps tend to do a good job with one of these, and rarely with both. In their paper, they emphasize that making apps user-friendly and fun to use, involving games and useful functions like species identification and social media plug-ins is a major missing piece among current apps.

“The greatest advancement in IAS early detection would likely result from app gamification,” they write.

Another feature they would like to see more of is artificial intelligence or machine learning for photo identification, which they believe would greatly enhance species identification and might increase public participation.

The authors also make suggestions for future innovations that could make IAS reporting apps even more effective. Their biggest suggestion is coordination.

“Currently, most invasive species apps are developed by many separate organizations, leading to duplicated effort and inconsistent implementation”, they say. “The valuable data collected by these apps is also sent to different databases, making it harder for scientists to combine them for useful research.”

A more efficient way to implement these technologies might be providing open-source code and app templates, with which local organizations can make regional apps that contribute data to centralized databases.

Overall, this research shows how with broader participation, more complete and informative reporting forms, and more consistent and structured data management, IAS reporting apps could make much larger contributions to invasive species management worldwide. This, in turn, could save local, regional, and national economies hundreds of millions or billions of dollars annually, while protecting valuable ecological and agricultural systems for future generations.

Research article:

Howard L, van Rees C, Dahquist Z, Luikart G, Hand B (2022) A review of invasive species reporting apps for citizen science and opportunities for innovation. NeoBiota 71: 165-188. https://doi.org/10.3897/neobiota.71.79597

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Australia’s wish list of exotic pets

In a new study, published in the peer-reviewed open-access scholarly journal Neobiota, scientists estimated the desire of Australians to own non-native and/or illegal alien pets and the major trends in this practice. In addition, the team suggests ways to improve biosecurity awareness in the country.

Juvenile green iguanas for sale at Repticon Trading Convention 2018 in Palm Springs, Florida
Photo by Adam Toomes

Unsustainable trade of species is a major pathway for the introduction of invasive alien species at distant localities and at higher frequencies. It is also a major driver of over-exploitation of wild native populations. In a new study, published in the peer-reviewed open-access scholarly journal Neobiota, scientists estimated the desire of Australians to own non-native and/or illegal alien pets and the major trends in this practice. In addition, the team suggests ways to improve biosecurity awareness in the country.

Over the last two decades, Australia has been experiencing an increased amount of non-native incursions from species prominent in the international pet trade, such as rose-ringed parakeets, corn snakes and red-eared sliders. On many occasions, these animals are smuggled into the country only to escape or be released in the wild.

In general, the Australian regulations on international pet trade are highly stringent, in order to minimise biosecurity and conservation risks. Some highly-desirable species represent an ongoing conservation threat and biosecurity risk via the pet-release invasion pathway. However, lack of consistent surveillance of alien pets held, legally or otherwise, in Australia remains the main challenge. While there are species which are not allowed to be imported, they are legal for domestic trade within the country. Pet keepers have the capacity to legally or illegally acquire desired pets if they are not accessible through importation, and the number of such traders is unquantified.

Since keeping most of the alien pets in Australia is either illegal or not properly regulated, it is really difficult to quantify and assess the public demand for alien wildlife.

A juvenile ball python for sale at Repticon Trading Convention 2018 in Palm Springs, Florida
Photo by Adam Toomes

“We obtained records of anonymous public enquiries to the Australian Commonwealth Department of Agriculture, Water and the Environment relating to the legality of importation of various alien taxa. We aimed to investigate whether species desired in Australia were biased towards being threatened by extinction, as indicated by broader research on pet demand or towards being invasive species elsewhere, which would indicate trade-related biosecurity risks”,
shares the lead author Mr. Adam Toomes from the University of Adelaide.

According to the research team’s analysis, pets desired by Australians are significantly biased towards threatened species, invasive species and species prominent in the U.S. pet trade.

“This novel finding is of great concern for biosecurity agencies because it suggests that a filtering process is occurring where illegally smuggled animals may already be “pre-selected” to have the characteristics that are correlated with invasive species,”
warns Mr. Adam Toomes.

However, the bias towards species already traded within the U.S. suggests that there is potential to use this as a means of predicting future Australian desire, as well as the acquisition of pets driven by desire. Future research from the Invasion Science & Wildlife Ecology Group at The University of Adelaide will investigate whether Australian seizures of illegal pets can be predicted using U.S. trade data.

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Original source:

Toomes A, Stringham OC, Mitchell L, Ross JV, Cassey P (2020) Australia’s wish list of exotic pets: biosecurity and conservation implications of desired alien and illegal pet species. NeoBiota 60: 43-59. https://doi.org/10.3897/neobiota.60.51431

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Experiment suggests the best ways to tackle invasive Oregon grape in Belgian coastal dunes

The Belgian coastal dunes, a protected habitat of high conservation value, are getting severely impacted by one of its worst enemies amongst invasive species: the Oregon grape. To help mitigate the detrimental effect of this North American shrub invader, Belgian scientists carried out an experiment to assess the effectiveness of different management methods.

The Atlantic coastal dunes form a dynamic and diverse ecosystem, home to a large number of native species, many of which are regionally threatened. Embryonic dunes, shifting white dunes, moss dunes, dune grasslands, and dune slacks are considered high conservation value sites, according to the interpretation manual of European habitats. However, the dunes are highly affected by external influences, and one of the most important threats to their biodiversity are invasive non-native plant species. These plants often colonised the dunes as garden escapes or spread from garden waste dumps or public plantings. Oregon grape is one of the worst invaders amongst them.

Oregon grape growing on sand dune (Belgium).
Photo by Tim Adriaens.

In their study, published in the open-access journal NeoBiota, the scientists, led by Tim Adriaens and Sam Provoost of the Research Institute for Nature and Forest (INBO), focus on the management of the current populations of Oregon grape (Berberis aquifolium) in the Belgian coastal dunes, where the species has already managed to invade half of the 46 nature reserves and is starting to replace native vegetation. Such a negative effect on the biodiversity of the area requires practical management advice. Due to the high level of infestation of the dunes, the researchers recommend prompt eradication as the most appropriate management strategy. So far, however, it has been unclear which method would show the best effectiveness.

“Invasive shrub species exert an additional pressure on Belgian dune ecosystems, which are already highly fragmented by urbanisation. Oregon grape is one of the worst and should be tackled urgently before it gets out of control,” says Tim Adriaens.

Having compared four previously suggested treatments: manual uprooting, foliar herbicide application, stem cutting followed by herbicide and salt application, the scientists reported herbicide leaf treatment to be the most effective method. Manual removal by digging and treating stems with glyphosate showed medium effectiveness. Treating stems with a saturated salt solution appeared rather cosmetic. However, it’s not that easy to choose which method would be the best to work with, since with herbicide use there are non-target effects on the environment, economy, and society to be considered.

Dune restoration by mechanical removal of dense Oregon grape infestation (left) and leaf treatment of Oregon grape clone with a hand sprayer (right).
Photo by Tim Adriaens.

“Individual clones are best treated with herbicide, large surface areas provide opportunities for landscape-scale ecological restoration, combining invasive shrub removal with sand dune creation,” further explains Tim Adriaens.

In Belgium, Oregon grape was first recorded in the wild in 1906 and naturalised in the period 1920-1950. It has been spreading rapidly since the 1990s. This expansion might be linked to cultivated hybrids and global warming, with the latter leading to a lengthened growing season, suggest the scientists. The species likes calcareous soils. Along the Belgian coast, Oregon grape has mainly invaded grey dunes, scrub and woodland.

Thanks to its numerous blue berries, which are easily dispersed over long distances by songbirds, the plant can appear everywhere within the dunes sites, also in places hardly accessible to managers. With the help of a highly branched root system, the plants attach themselves firmly in the sand, which makes manual pulling of mature plants hardly possible and labor-intensive.

“Dune managers and scientists across Europe should unite to draft alert lists and prioritise established alien species for management,” Tim says in conclusion.

In conclusion, the scientists highlight the importance of an EU-wide collaboration between scientific communities. Invasive species are not bothered by administrative borders and exchanging experiences on impact and management options is crucial to maintain dune ecosystems in good conservation status.

Coastal dunes in Belgium provide unique habitat to many Red listed species.
Photo by Tim Adriaens.

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Original source

Adriaens T, Verschelde P, Cartuyvels E, D’hondt B, Vercruysse E, van Gompel W, Dewulf E, Provoost S (2019) A preliminary field trial to compare control techniques for invasive Berberis aquifolium in Belgian coastal dunes. NeoBiota 53: 41-60. https://doi.org/10.3897/neobiota.53.38183

Long-distance survival: Effects of storage time and environmental exposure on soil bugs

Contaminated soil frequently arrives at the borders through transported items, and is widely recognised as a vector for non-native species, potentially threatening the local agriculture, horticulture and natural ecosystems. However, although soil is the target of management practices that aim to minimise the spread of invasive alien species, crucial knowledge of the biosecurity hazards that can accompany transported soil is currently lacking. While not much is known about the relative survival rates of the transported soil organisms, nor about their establishment probabilities, this information is essential to support optimal policy and management decisions.

A recent study, led by Mark McNeill from AgResearch’s Biosecurity and Biocontrol team at Lincoln, New Zealand, and published in the open access journal NeoBiota, shows that biosecurity risks from soil organisms are to increase with declining transport duration and increasing protection from environmental extremes. The scientists sought the answer of a simple question – are soil organisms still risky after a year in the sun?

To find out, Mark and his team collected soil from both a native forest and an orchard and stored it on, in and under sea containers, as well as in cupboards. They tested it after three, six and twelve months for bacteria, fungi, nematodes and seeds.

“Soil can carry unwanted microbes, insects and plants, and this study showed that some died faster when exposed, than when protected in a cupboard. This work shows some of the risks presented by soil contamination,” Mark says.

“The results showed that viability of certain bacteria, nematodes and plants declined over 12 months, irrespective of soil source and where the soil was stored. But mortality of most organisms was higher when exposed to sunlight, moisture and desiccation than when protected,” he explains. “However, bacterial and fungal numbers were higher in exposed environments, possibly due to ongoing colonisation of exposed soil by airborne propagules.”

“The results were consistent with previous observations that organisms in soil intercepted from seaports tend to carry less bugs than soil found on footwear,” McNeill notes.

“The research also raised wider questions, because some results were unexpected, including trying to understand why the microbe numbers went up and down like they did in the soil sitting on the sea containers when everything else died off. Was it the circle of life or just new microbe migrants creating new populations?

“We hope that the work will be useful for plant quarantine authorities to assess the risk presented by transported soil based partly on where the soil is found and the age of the soil. This would help authorities to optimally allocate management resources according to pathway-specific risks. Importantly, the study will assist in the development of recommendations for increasing management efficiency and efficacy at national borders.”

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Original source:

McNeill MR, Phillips CB, Robinson AP, Aalders L, Richards N, Young S, Dowsett C, James T, Bell N (2017) Defining the biosecurity risk posed by transported soil: Effects of storage time and environmental exposure on survival of soil biota. NeoBiota 32: 65-88. https://doi.org/10.3897/neobiota.32.9784