How much are ecological invasions costing us? A considerable amount!

Reports of invasive alien species (IGOs) are not going quiet. We hear more and more in the media about more IGOs that are (actually or allegedly) ruining our native universe. And it’s that we need to get rid of rosette pistachios from backyard ponds and aquariums, because there is a risk that these alien aquatic plants will threaten native flora. And it’s the appearance of exotic mosquitoes that carries the risk of epidemics hitherto unknown in our areas. Or a dispute is unleashed in the media over the eradication of the god-forsaken nutria. Examples can be multiplied. Most citizens ignore such reports or treat them in the category of ecological curiosities. Well, because why should biological invasions concern the average citizen? Maybe because it costs money! And it is not at all so indifferent to our economies.

Ecological invasions are a real cost

Alien invasive species (IGOs) have an undeniable impact on many aspects of the areas they have managed to occupy, including biodiversity, ecosystem services and human well-being. Many countries are enacting a range of national and international strategies, policies, regulations and bans aimed at preventing new introductions and limiting the geographic spread of IGOs. And yet the number of species defined as alien is growing. It is estimated to increase by 36 percent over the next three decades. A number of factors contribute to this, such as habitat degradation, climate change and the increasing frequency, intensity and diversity of anthropogenic vectors associated with the globalization of trade and transportation.

In recent years, our knowledge in understanding the impact of invasive alien species on ecosystems, factors influencing invasion success, management or assessing the economic dimensions of this phenomenon has expanded significantly. However, studies of the economic aspects of IGOs are usually limited to certain taxonomic groups, communities or regions. In particular, the costs of aquatic IGOs are much less well recognized than those resulting from invasions of terrestrial species, which are more often the objects of study.

Aquatic ecosystems can be seriously threatened by invasive alien species, which contribute to the elimination of local species, significantly alter the structure of native communities and the functioning of entire ecosystems. Thus, IGOs affect the ecosystem services of waters, and this can already have purely economic consequences. The availability of comprehensive and systematically collected data on the water costs of IGOs is a prerequisite for effective planning and prioritization of IGO management. Such data would also be useful in communicating with decision-makers and the general public. After all, it is no secret that impacts expressed in economic terms are more tangible and understandable to most of us than complex ecological impacts. Yet such data is still severely lacking.

InvaCost database – a source of data on the cost of ecological invasions

A systematic attempt to describe global patterns and trends in reported costs of aquatic invasive species was undertaken by an international team of scientists led by British biologist Ross Cuthbert. The researchers based their estimates on data collected at InvaCost, and published the results in 2021. in the journal Science of the Total Environment. The database used by the authors currently contains the most comprehensive and up-to-date set of data on the cost of the presence of alien species worldwide.

The database collects all reported economic costs related to IGO, both those that have already become invasive (e.g., management, damage and loss costs) and those that may become invasive in the future (e.g., prevention and eradication costs). To ensure comparability, costs in InvaCost are standardized against a single currency (USD) and converted on an annual basis. At the time Cuthbert and co-authors conducted their analysis, the database included more than 9,800. entries (currently, that is, as of September 2024, there are more than 13,500). After appropriate data selection, the authors used information from approx. 5.7 thousand. entries concerning aquatic and semi-aquatic (semiaquatic) species.

A weakness of the database is that if something has not been reported to it, it is not in it, which does not mean that it does not exist. For this reason, the presented results must be approached with caution and treated rather as severely underestimated, both in terms of cost and geographic and taxonomic representativeness.

How much does a mosquito cost and how much does a nutria cost?

An analysis of 5,700 entries from the InvaCost database showed the cost of aquatic IGOs (published after 1971) at $345 billion, with aquatic species costing $149 billion and semi-aquatic species $185 billion. Surprisingly, only 1 percent of the costs were for marine species ($3.6 billion), but here again one must keep in mind the limitations of the base. Costs were unevenly distributed across taxonomic groups, with the majority (62 percent) attributed to invertebrates, 28 percent to vertebrates and 6 percent to plants. All other taxonomic groups together accounted for 4 percent of the total reported ecological costs of invasives.

The vast majority of the global cost of the invasion, 88 percent. (more than $300 billion), were generated by just 10 species – four invertebrates, three vertebrates and three plants. More than half of the costs were caused by mosquitoes belonging to three species of the genus Aedes, followed by the European weevil(Gymnocephalus cernua), two species of mussels(Dreissena polymorpha and D. bugensis), nutria(Myocastor coypus), and three species of ludwigia, sometimes known as the tilefish(Ludwigia spp.).

The huge costs attributed to exotic mosquito infestations are not surprising, given that these insects are major vectors of pathogens and parasites, and the diseases they transmit generate a huge burden on health systems around the world. According to the study’s authors, the Brazilian government from 2015 to 2017. invested approx. 48 million dollars. per year to reduce the Aedes aegypti invasion. The total cost of treating dengue-infected patients in Colombia between 2010 and 2012 reached $3 billion, and the recent outbreak of chikunguni cost the health system there about $76 million.

Mosquitoes can also cause economic losses related to recreation and tourism, as they discourage people from engaging in certain activities or visiting endangered areas. Future expansions in the range of invasive mosquitoes are projected to increase their economic impact. And given that they are also already appearing in Poland, get your cash ready!

The second most expensive reported species is the European ruffe, a fish in the perch family that in North America, through predation and competition, leads to a decline in populations of native fish, including commercially and recreationally valuable species. And this causes significant economic consequences. In our country it’s a native species, for America a threatening IGO. On the other hand, crayfish(Dreissena polymorpha and D. bugensis) are very costly to infrastructure, as they impede navigation, block the flow of water in pipes and clog filters through their mass occurrence.

These are the most abundant organisms reported to the base from the European area. Nutria(M. coypus) causes significant economic losses through its impact on agriculture, as well as infrastructure damage. On the other hand, aquatic plants, such as ludwigia, reduce water quality, displace native species (not only flora, but also affect commercially important fish), and through their growth, usually indiscriminate and difficult to control, are extremely costly to eradicate. In general, aquatic plants lead the way in ranking the number of reports of economic damage.

How much is America spending on environmental invasions, and how much is Africa spending?

The reported economic costs of aquatic invasive alien species are distributed unevenly in different parts of the world. The highest are in North America (48 percent, $166 billion), while Asia accounts for only 13 percent. ($45 billion). Costs in Europe and South America together accounted for 12 percent. ($41 billion). Africa, the islands of Oceania and the Pacific, and Antarctica and the Subantarctic combined accounted for only 0.6 percent. ($2.1 billion) of the total cost of the invasion. A significant portion (26 percent) of the costs were not allocated to specific geographic regions.

The United States showed the highest costs and the highest number of studies compared to all other countries. This is not surprising, given that research on the economic aspect of ecological invasions has been conducted in this country for the longest time. Brazil, India and France were next in terms of cost. Elsewhere, the results were on a level playing field.

It is worth noting that the InvaCost database does not include reported costs for aquatic IGOs for most African and Asian countries. Even in countries such as South Africa, where research on biological invasions is well developed, large gaps in knowledge of the economic costs of this phenomenon are apparent. South Africa is a global hotspot of alien freshwater fish invasions, with significant negative impacts on human welfare. The limited reporting of costs in Africa and Asia likely reflects the low priority of such research.

The authors do not specify this, but the authors’ own analysis of the available version of the database indicates that among European countries, Spain, France, the UK and Norway have the highest number of submissions. From the territory of Poland, unfortunately, there is not a single one. Could it be that in our country the problem of the economics of biological invasions is also not a priority?

What costs in the future? Well, of course, higher!

Most of the models analyzed by the authors indicate an exponential increase in the annual water costs of invasive alien species, beginning in 1960. The models’ predictions are consistent with increasing rates of biological invasions worldwide, driven by globalization and intensification of trade and transportation networks that favor IGO dispersal. The problem is also exacerbated by climate change and associated shifts in habitat and species ranges.

Given that invasion rates will continue to rise, we can certainly expect further increases in the costs associated with prevention, eradication and mitigation. Moreover, bearing in mind that the base does not take into account unreported costs or those resulting from the future spread of IGOs, the results presented must be regarded as a far underestimate. Just knowing how much money has been invested in managing alien species in other countries, will it allow us to guard against or adequately prepare for an invasion? I sincerely doubt it!