ArticlePDF Available

Abstract and Figures

Much research effort has been invested in understanding ecological impacts of invasive alien species (IAS) across ecosystems and taxonomic groups, but empirical studies about economic effects lack synthesis. Using a comprehensive global database, we determine patterns and trends in economic costs of aquatic IAS by examining: (i) the distribution of these costs across taxa, geographic regions and cost types; (ii) the temporal dynamics of global costs; and (iii) knowledge gaps, especially compared to terrestrial IAS. Based on the costs recorded from the existing literature, the global cost of aquatic IAS conservatively summed to US$345 billion, with the majority attributed to invertebrates (62%), followed by vertebrates (28%), then plants (6%). The largest costs were reported in North America (48%) and Asia (13%), and were principally a result of resource damages (74%); only 6% of recorded costs were from management. The magnitude and number of reported costs were highest in the United States of America and for semi-aquatic taxa. Many countries and known aquatic alien species had no reported costs, especially in Africa and Asia. Accordingly, a network analysis revealed limited connectivity among countries, indicating disparate cost reporting. Aquatic IAS costs have increased in recent decades by several orders of magnitude, reaching at least US$23 billion in 2020. Costs are likely considerably underrepresented compared to terrestrial IAS; only 5% of reported costs were from aquatic species, despite 26% of known invaders being aquatic. Additionally, only 1% of aquatic invasion costs were from marine species. Costs of aquatic IAS are thus substantial, but likely underreported. Costs have increased over time and are expected to continue rising with future invasions. We urge increased and improved cost reporting by managers, practitioners and researchers to reduce knowledge gaps. Few costs are proactive investments; increased management spending is urgently needed to prevent and limit current and future aquatic IAS damages
Content may be subject to copyright.
Global economic costs of aquatic invasive alien species
Ross N. Cuthbert
, Zarah Pattison
, Nigel G. Taylor
, Laura Verbrugge
, Christophe Diagne
Danish A. Ahmed
, Boris Leroy
, César Capinha
Tatenda Dalu
, Franz Essl
, Rodolphe E. Gozlan
, Phillip J. Haubrock
, Melina Kourantidou
Andrew M. Kramer
, David Renault
, Ryan J. Wasserman
, Franck Courchamp
GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, 24105 Kiel, Germany
South African Institute for Aquatic Biodiversity, Makhanda 6140, South Africa
Modelling, Evidence and Policy Research Group, School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
Tour du Valat, Research Institute for the Conservation of Mediterranean Wetlands, 13200 Arles, France
University of Helsinki, Faculty of Agriculture and Forestry, Department of Forest Sciences, P.O. Box 27, 00014 Helsinki, Finland
Aalto University, Department of Built Environment, Water & Development Research Group, Tietotie 1E, FI-00076 Aalto, Finland
Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Systématique Evolution, 91405 Orsay, France
Centerfor Applied Mathematics and Bioinformatics(CAMB), Department of Mathematics andNatural Sciences,Gulf Universityfor Science and Technology, P.O.Box 7207, Hawally32093, Kuwait
Biologie des Organismes et Ecosystèmes Aquatiques (BOREA), Muséum national d'Histoire naturelle, CNRS, IRD, Sorbonne Université, Université Caen-Normandie, Université desAntilles, 43 rue
Cuvier, CP 26, 75005 Paris, France
Centro de Estudos Geográcos, Instituto de Geograa e Ordenamento do Território IGOT, Universidade de Lisboa, Lisboa, Portugal
Department of Geography, King's College London, Strand WC2B 4BG, UK
School of BioSciences, University of Melbourne, Vic 3010, Australia
School of Biology and Environmental Sciences, University of Mpumalanga, Nelspruit 1200, South Africa
BioInvasions, Global Change, Macroecology-Group, Department of Botany and Biodiversity Research, University Vienna, Rennweg 14, 1030 Vienna, Austria
ISEM UMR226, Université de Montpellier, CNRS, IRD, EPHE, 34090 Montpellier, France
Senckenberg Research Institute and Natural History Museum, Frankfurt, Department of River Ecology and Conservation, Gelnhausen, Germany
University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, South Bohemian Research Center of Aquaculture and Biodiversity of Hydrocenoses, Zátiší 728/II,
389 25 Vodňany, Czech Republic
Woods Hole Oceanographic Institution, Marine Policy Center, Woods Hole, MA 02543, United States
Institute of Marine Biological Resources and Inland Waters, Hellenic Center for Marine Research, Athens 164 52, Greece
University of Southern Denmark, Department of Sociology, Environmental and Business Economics, Esbjerg 6705, Denmark
Department of Integrative Biology, University of South Florida, Tampa, FL 33620, United States
Univ Rennes,CNRS, ECOBIO [(Ecosystèmes, biodiversité, évolution)], - UMR 6553, F 35000 Rennes, France
Institut Universitaire de France, 1 Rue Descartes, 75231 Paris cedex 05, France
Department of Zoology and Entomology, Rhodes University, Makhanda 6140, South Africa
Aquatic invasions have cost the global
economy US$345 billion.
Most costs are caused by invertebrates,
in North America and damages to re-
Costs have increased exponentially over
time, to at least US$23 billion in 2020.
Aquatic invasion costs are underrepre-
sented compared to terrestrial invasion
Taxonomic, geographic and tempo-
ral gaps make these costs severely
Science of the Total Environment 775 (2021) 145238
Corresponding author at: GEOMAR, Helmholtz-Zentrum für Ozeanforschung Kiel, 24105 Kiel, Germany.
E-mail address: (R.N. Cuthbert).
0048-9697/© 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (
Contents lists available at ScienceDirect
Science of the Total Environment
journal homepage:
abstractarticle info
Article history:
Received 12 November 2020
Received in revised form 6 January 2021
Accepted 13 January 2021
Available online 20 January 2021
Editor: Damia Barcelo
Habitat biases
Monetary impact
Much research effort has been invested in understanding ecological impacts of invasive alien species (IAS)across
ecosystems and taxonomic groups, but empirical studies about economic effects lack synthesis. Using a compre-
hensive global database,we determine patternsand trends in economic costs of aquatic IASby examining: (i)the
distribution of these costs across taxa, geographic regions and cost types; (ii) the temporal dynamics of global
costs; and (iii) knowledge gaps, especially compared to terrestrial IAS. Based on the costs recorded from the
existing literature,the global cost of aquatic IAS conservatively summed to US$345 billion, with the majority at-
tributed to invertebrates (62%), followed by vertebrates (28%), then plants (6%). The largest costs were reported
in North America (48%) and Asia (13%), and were principally a result of resource damages (74%); only 6% of re-
corded costs were from management. The magnitude and number of reported costs were highest in the United
States of America and for semi-aquatic taxa. Many countries and known aquatic alien species had no reported
costs, especially in Africa and Asia. Accordingly, a network analysis revealed limited connectivity among coun-
tries, indicating disparate cost reporting. Aquatic IAS costs have increased in recent decades by several orders
of magnitude, reaching at least US$23 billion in 2020. Costs are likely considerably underrepresented compared
to terrestrial IAS; only 5% of reported costs were from aquatic species, despite 26% of known invaders being
aquatic. Additionally, only 1% of aquatic invasion costs were from marine species. Costs of aquatic IAS are thus
substantial, but likely underreported. Costs have increased over timeand are expected to continue rising with fu-
ture invasions. We urgeincreased and improved cost reporting by managers, practitioners and researchers to re-
duce knowledge gaps. Few costs are proactive investments; increased management spending is urgently needed
to prevent and limit current and future aquatic IAS damages.
© 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
1. Introduction
The impacts of invasive alien species (IAS) on biodiversity (Mollot
et al., 2017;Spatz et al., 2017;Shabani et al., 2020), ecosystem services
(Vanbergen, 2013;Blackburn et al., 2019) and human wellbeing
(Pejchar and Mooney, 2009) are well recognized (Pyšek et al., 2020). Ac-
cordingly, there are numerous national and international policies, regula-
tions and mandates in place to prevent new introductions and limit the
geographic spread of IAS [e.g. Convention on Biological Diversity (UNEP,
2011); European Union Regulation 1143/2014 on IAS]. However, records
of IAS are continuously increasing, owing to factors such as habitat distur-
bance, climate change, and an increasing diversity, frequency and inten-
sity of anthropogenic vectors associated with globalising trade and
transport networks (Capinha et al., 2015;Seebens et al., 2017, 2018;
Turbelin et al., 2017;McGeoch and Jetz, 2019). Alien species numbers
are burgeoning across geographical regions and habitat types, with the
number of established alien species expected to increase by 36% in the
next three decades (Seebens et al., 2020).
Aquatic ecosystems can be severely threatened by IAS, which
contribute to extinctions of individual species, substantially
change the structure of native communities, and alter ecosystem
functioning (Vitousek et al., 1997;Ricciardi and MacIsaac, 2011;
Jackson et al., 2017). Aquatic ecosystems provide numerous ser-
vices to people, from food provision to ood protection and recrea-
tion; these services can also be critically altered by the presence of
IAS (e.g. Katsanevakis et al., 2014). The vulnerability of aquatic eco-
systems to invasions is increased by high interconnectedness
among habitats, specically man-made waterways and shipping,
as well as other anthropogenic pressures (Strayer and Findlay,
2010;Poulin et al., 2011;Darwall et al., 2018) and climate shifts
(Woodward et al., 2010).
In recent years there have been signicant advances across habitat
types in understanding ecological impacts of IAS (Kumschick et al.,
2015;Dick et al., 2017; but see Crystal-Ornelas and Lockwood, 2020)
and the drivers of invasion success (Cuthbert et al., 2019, 2020;
Fournier et al., 2019;van Kleunen et al., 2020), as well as methodologi-
cal advances in assessing the economic dimensions of IAS and their
management (Lovell et al., 2006;Hanley and Roberts, 2019). However,
studies of economic aspects of IAS have been limited to certain
taxonomic groups (Bradshaw et al., 2016), communities, or regions
(Pimentel et al., 2000;2005;Kettunen et al., 2009;Cuthbert et al.,
2021;Haubrock et al., 2021). In particular, costs of aquatic IAS are
generally less well understood than costs of terrestrial IAS, despite
some estimates indicating high costs (Lovell et al., 2006;Aldridge and
Oreska, 2011). Comprehensive and systematically-assembled data on
the costs of aquatic IAS would greatly help planning and prioritisation
for their management, in the context of limited resources (McGeoch
et al., 2015). Such data would also provide a useful resource for commu-
nications with policymakers and the general public: impacts expressed
in economic terms are more tangible and comprehensible than complex
ecological impacts (Diagne et al., 2020a).
This paper is the rst systematic effort to describe global pat-
terns and trends in reported costs of aquatic IAS. Our analysis,
based on the recently developed InvaCost database (Diagne et al.,
2020b), allows us to synthesise standardised costs, identify knowl-
edge gaps and provide recommendations for management and fur-
ther research. We describe the global monetary costs associated
with aquatic IAS based on taxonomic, geographic and temporal de-
scriptors, as well as between fully aquatic and semi-aquatic taxa. In
doing so, we examine (i)howcostsarestructuredbyimplementa-
tion method (i.e. observed vs. potential/expected), (ii) reliabilities
of cost estimates and (iii) their typology, i.e., whether costs result
from damages and losses or management expenditure. Further,
we model the yearly and cumulative dynamics of costs and investi-
gate whether they are likely to saturate in the near future. Finally,
we assess potential biases between aquatic and terrestrial cost
reporting. These biases are then used to identify gaps in manage-
ment spending between habitats.
2. Materials and methods
2.1. Original data
For the purpose of quantifying global costs of aquatic IAS, we used the
most comprehensive and up-to-date dataset of costs caused by alien spe-
cies globally, assembled by the InvaCost project (Diagne et al., 2020a,
2020b). At time of writing, this includes 9823 entries in various lan-
guages from systematic and opportunistic literature searches (Diagne
et al., 2020b;Angulo et al., 2021; full database version 3 at https://doi.
org/10.6084/m9.gshare.12668570). This database captures any re-
ported economic costs associated with IAS in their novel range, including
those for species that have already become invasive (e.g. management,
damages and losses) and species that may become invasive in the future
(e.g. prevention and rapid eradication).
R.N. Cuthbert, Z. Pattison, N.G. Taylor et al. Science of the Total Environment 775 (2021) 145238
The InvaCost version 3 database contains a column ("Environment_
IAS") which classies species as either aquatic (species with a close associ-
ationwithaquaticsystemsatanylifestage, including for reproduction,
development and/or foraging; n= 2317 cost entries after our below cor-
rections) or terrestrial (n= 6433 cost entries after our below correc-
tions), independently of where costs occurred. For some analyses, we
split out costs for semi-aquatic species: the subset of aquatic species
with a looser association with aquatic systems (see Supplementary
Material 1). Remaining entries, linked to species from diverse habitats
(i.e. a mixture of aquatic and terrestrial) or unspecied habitats, were
excluded from analyses. Wealso carefully screened the published data-
base, removing clear duplicates and correcting clear mistakes. All mod-
ications made in our dataset were sent to as
recommended by the database managers.
Briey, costs in InvaCost are standardised against a single currency
for comparability (2017 US$); costs in the database may be expanded
so that entries can be considered on an annual basis. That means that
costs spanning multiple years (e.g. $10 million between 2001 and
2010) are divided according to their duration (e.g. $1 million for each
year between 2001 and 2010); we considered this expanded database
version in all analyses (Supplementary Materials 1; n= 5682 aquatic en-
tries). Expansion was done using the expandYearlyCosts function of the
invacostRpackage(R Core Team, 2020;Leroy et al., 2020). The nal,
unexpanded dataset used in our analyses is provided as Supplementary
Material 2. We note that 1 billion = 1 × 10
2.2. Cost descriptors
To obtain a general overview of the costs associated with IAS, we
rst illustrated them across a number of key database descriptors
(see Supplementary Material 1 and
gshare.12668570 for complete details). These included (1) broad
taxonomic grouping of species presenting costs (invertebrates, ver-
tebrates, plants, other), (2) perceived reliability of each cost entry
(Highvs. Low), (3) cost implementation type (Observedvs.
Potential), (4) geographic region in which the cost occurred
(within continent- and country- scales) and (5) cost type (Damage
vs. Management). We summed the expanded entries (see above)
to quantify cost totals among these descriptors.
2.3. Spatial and taxonomic connectivity
We investigated spatial and taxonomic patterns in costs of aquatic
IAS with a network analysis (see Supplementary Material 1). Here, we
created a bipartite network composed of two types of nodes: countries
and IAS. When a species had a reportedeconomic impact in a country, a
link was drawn between the two nodes. The weight of the link was
equal to the cumulative cost, since 1960. We dened the size of nodes
on the network as proportional to their total costs with a log spline,
such that country or species nodes with higher costs are easier to distin-
guish from those with lower economic impacts.
2.4. Prediction of annual costs for aquatic IAS
To examine themost appropriate temporal relationship forthe accu-
mulation of costs over time, we used the modelCosts function of the
invacostpackage (Leroy et al., 2020). We tted multiple models to
the data and identied the best model(s) by quantitative and qualitative
criteria (see Supplementary Material 1). As we were dealing with
econometric data, we selected models that were robust to issues of
heteroskedasticity, temporal autocorrelation and outliers. We exam-
ined the long-term trend of annual costs worldwide between 1960
and 2020, i.e., we predicted costs as a function of years. First, owing to
time lags in cost reporting, we corrected the data by removing the
most recent, thus incomplete years; not making this correction would
result in an inherent underestimation of costs (Supplementary Material
1). Second, we employed and compared a range ofstatistical techniques
on the resulting data:ordinary least squares regression (linearand qua-
dratic), robust regression (linear and quadratic), multivariate adaptive
regression splines, generalised additive models(GAMs) and quantile re-
gression [0.1 (lower boundary of cost), 0.5 (median cost value), 0.9
(upper boundary of cost)].
2.5. Trend in cumulated costs for aquatic IAS
In addition to modelling annual costs, we mathematically described
temporal changes in cumulated costs of aquatic IAS. We chose to rely on
a variation of the functional form proposed by Yokomizo et al. (2009)
for density-impact curves, where we considered the cumulative cost C
in terms of population density u. By assuming logistic growth in the
population, Ccan then be expressed as a function of time and therefore
serves as a model for the cumulative temporal cost of impacts (Supple-
mentary Material 1). We used a non-linear regression curve-tting tool
to estimate the best t parameters, such as cost saturation C
, carrying
capacity Kand intrinsic growth rate α.Wequantied the t by comput-
ing the squared correlation coefcient (r
) and root mean square error
2.6. Reporting of invasion costs from aquatic IAS compared to terrestrial IAS
We obtained known numbers of established alien species (n=
13,867) in aquatic and terrestrial habitats globally, using databases
such as the inventory of IAS in Europe (DAISIE; see Supplementary
Material 1 for full list of sources). Categorising entries originating from
either aquatic or terrestrial species, we then counted for the two habi-
tats in InvaCost: the numbers of species havingcosts (excluding unspe-
cic entries), the number of documents reporting these costs, total
costs, and costs only reporting management actions (not reporting
damage). Then, we compared these numbers to the proportions of
known established IAS between habitats. Finally, we predicted the ex-
pected costs of management actions for aquatic IAS, under the hypoth-
esis of an unbiased expenditure between aquatic and terrestrial habitats
(based on the known proportion of global aliens that are aquatic).
3. Results
3.1. Global costs and taxonomic groupings
Global costs of aquatic IAS summed to US$345 billion, based on 5682
records from the expanded InvaCost database. These were all published
since 1971. Semi-aquatic species cost US$185 billion (n= 2971 records)
and fully aquatic species US$149 billion (n= 2518 records), with diverse
costs (that spanned semi-aquatic and fully aquatic species) comprising
the remaining US$11 billion (n= 193 records). Only 1% of the cost was
from fully marine species (US$3.6 billion; n=234records).
Costs were unevenly distributed across taxonomic groups, with the
majority (62%, US$214 billion) attributed to invertebrates, 28% (US$97
billion) to vertebrates and 6% (US$20 billion) to plants. All other taxo-
nomic groups accounted collectively for 4% (US$14 billion) of the total
costs (Fig. 1). Highly reliable (i.e. peer-reviewed or traceable) sources
contributed 79% (US$274 billion) of the documented total costs of
aquatic IAS (Fig. 1a). The majority of thetotal costs for animals (inverte-
brates: 76%; vertebrates: 88%) and plants (65%) were based on highly
reliable sources.
Most (65%, US$224 billion) of the costs were derived from empirical
observations, rather than predictions (Fig. 1b). The majority of costs for
aquatic invertebrates were derived from empirical observations (92%).
However, just 17% of the costs for aquatic vertebrates and 42% of plant
costs, were based on empirical observations.
The 10 aquatic genera with the highest documented costs accounted
for US$304 billion (88%) of total costs (Fig. 2). These taxa included four
invertebrates, three vertebrates and three plants. Mosquitoes belonging
R.N. Cuthbert, Z. Pattison, N.G. Taylor et al. Science of the Total Environment 775 (2021) 145238
to three species of the Aedes genus caused 50% (US$153 billion) of the
total top 10 cost. These were followed by ruffes Gymnocephalus cernua
(18%, US$53 billion), mussels Dreissena spp. (two species, 16%, US$50
billion), coypus Myocastor coypus (6%, US$19 billion) and primroses
Ludwigia spp. (three species, 3%, US$8 billion). Contributions from
the remaining genera were relatively small. For all genera, excepting
Lithobates, damages outweighed reported management spending
(Fig. 2).
3.2. Geographic regions
Reported economic costs of aquatic IAS were unevenly distributed
across geographic regions (Fig. 3). North America, owing to costs
primarily from the United Statesof America (USA), reported the highest
costs (48%, US$166 billion), followed by costs that were not attributed
to specic regions (26%, US$91 billion) and costs from Asia (13%, US
$45 billion). The costs in Europe and South America accounted
collectively for 12% (US$41 billion) of total reported costs, whilst
Africa, Oceania-Pacic Islands and the Antarctic-Subantarctic, combined
accounted for 0.6% (US$2.1 billion) (Fig. 3). Regarding cost types, 74%
(US$256 billion) of global costs were driven by damages, whereas
only 6% (US$21 billion) consisted of management-related expenditure
(Fig. 3b). Mixed spending (i.e. combined records of damage and
management-related spending) comprised 20% of global costs (US$68
billion). Further information on taxonomic and cost typology break-
downs per region is provided in Supplementary Material 1.
At the country level, the USA had the highest recorded cost for
aquatic IAS, followed by Brazil, India and France (Fig. 4a); other
Fig. 1. Balloon plots illustrating global monetary costs of aquatic invasive alien species across major taxonomic groupings, with respect to (a) method reliability and (b) implementation
type. Figures below each balloon correspond to the numbers of entries from the expanded database.
Fig. 2. Totalmonetary costsof the top 10 costly aquaticinvasive alien genera,alongside species-specicinformationof underlying data pertaining to each genus. Unspeciedspecies within
each genus were also included. Fills illustrate cost type contributions per genus. Note that Managementcorresponds to expenditure related to activities such as prevention, control,
eradication and research, whilst Mixedis a mixture of cost types.
R.N. Cuthbert, Z. Pattison, N.G. Taylor et al. Science of the Total Environment 775 (2021) 145238
countries were rela tively similar in costs. The USA also had the largest
number of studies. Other countries that reported costs generally had
similar numbers of studies, with numbers from, for example, Spain,
Brazil and Australia relatively high (Fig. 4b). We found no reported
costs for aquatic IAS from the majority of African and Asian countries.
3.3. Spatial and taxonomic connectivity
We found eight clusters of IAS costs that were composed of at least
ve nodes (coloured clusters in Fig. 5), and eleven minor clusters that
were composed of only two nodes (grey nodes in Fig. 5). We found two
types of clusters. First, most clusters were composed of one or a few coun-
tries and a unique combination of IAS. This was the case, for example, for
countries with the highest costs (mainly European and North American
countries), which often had clusters of their own. Among these unique
country clusters, the USA example was pervasive, with highest reported
costs for Dreissena spp., G. cernua and Melaleuca quinquenervia,alongside
many other IAS that were unique to that country. Second, there was one
cluster that was driven by one genus, Aedes, which had pantropical eco-
nomic impacts as well as impacts in temperate countries. For most of
the Southern Hemisphere countries, Aedes was the only genus for which
costs were reported. Despite these specic clusters of costly IAS per
country, several IAS taxa had widespread economic impacts on multiple
countries, such as Lithobates catesbeianus,M. coypus,Neovison vison,
Dreissena spp., Hydrocotyle ranunculoides and Eichhornia crassipes.Inter-
estingly, we found no strong biogeographical structure in the network.
Australia, for example, shared costly IAS with geographically disparate re-
gions such as European countries, South Africa, Argentina and Chile.
3.4. Prediction of annual costs for aquatic IAS
The linear models projected the highest costs of aquatic IAS in the
year 2020 (since 1960; data from years 2013 to 2020 were removed
owing to <75% completeness), however they had a relatively poor
t, with high RMSE (Fig. 6; Supplementary Material 1). The quadratic
robust regression was removed owing to cost reductions in recent
years, but it also had the highest RMSE (0.63). The GAM approach
thus provided the best ttothedata(ΔRMSE 0.08; Fig. 6). This
model indicated a rapid increase in costs by three orders of magni-
tude between 1970 and 2000, followed by a relatively gradual in-
crease within a further magnitude since 2000 (Fig. 6c).Overall,the
best-tting GAM predicted a cost o f aquatic IAS of US$23 bil lion glob-
ally in the year 2020.
3.5. Trend in cumulated costs for aquatic IAS
We found that the linear curve and high threshold curve models
performed well, with the former providing a slightly better t
(Table S1; Supplementary Material 1). In the long term, the cumula-
tive cost saturates to a xed value C
(i.e. maximum cumulative
cost of impact), where the invasion is completely controlled and no
further impact costs are incurred (Fig. 7). A clear saturation in costs
(i.e. carrying capacity) was not reached for either the full or adjusted
dataset (with outliers removed), indicating that costs will continue
to increase in the near future. The reduction in rate of cost increases
over recent years was likely an artefact of time lags in cost reporting
versus occurrence.
3.6. Reporting of invasion costs of aquatic IAS compared to terrestrial IAS
Of 13,867 known established alien species worldwide (see Supple-
mentaryMaterial 1), 26% are associated with aquatichabitats, compared
Fig. 3. Totalaquatic invasioncosts across geographic regions with respect to (a) taxonomic
groupingsand (b) cost types. Note in (b), that Managementcorresponds to expenditure
relatedto activities suchas prevention,control, eradication and research, whilst Mixedis
a mixture of cost types.
Fig. 4. Maps illustrating global distribution of (a) total economic costs and (b) number of
studies (i.e. unique documents) for aquatic invasive alien species. Costs unattributable to
individual countries were excluded (US$110 billion, out of a total US$345 billion; n =
37 study per country data points, out of a total 526). Costs with a known location in the
territorial waters of each country are also included in the displayed data. Total costs are
presented on a log
R.N. Cuthbert, Z. Pattison, N.G. Taylor et al. Science of the Total Environment 775 (2021) 145238
Dreissena spp.
Gymnocephalus cernua
Melaleuca quinquenervia
Corbicula fluminea
Petromyzon marinus
Hydrilla sp.
Lythrum salicaria
Hydrilla verticillata
Teredo navalis
Sporobolus cynosuroides
Myriophyllum spicatum
Sporobolus alterniflorus
Spartina spp.
Carcinus maenas
Styela clava
Eichhornia sp.
Spartina sp.
Lepidium latifolium
Codium fragile Bythotrephes longimanus
Phragmites australis
Myriophyllum sp.
Morone chrysops
Panicum repens Orconectes rusticus
Salmo trutta
Ciona intestinalis
Python bivittatus
Channa argus
Myriophyllum heterophyllum
Hymenachne amplexicaulis
Esox lucius
Ascophyllum nodosum
Solanum tampicense
Brachiaria mutica
Aedes spp.
Anopheles darlingi
Ludwigia peploides
Limnoperna fortunei
Ludwigia sp.
Mytilopsis trautwineana
Egeria densa
Potamogeton sp.
Threskiornis aethiopicus
Xenopus laevis
Ficopomatus enigmaticus
Pterois volitans
Coptodon zillii
Pa nic um maxi mum
Pterygoplichthys sp.
Ameiurus nebulosus
Saururus cernuus
Cygnus atratus
Lithobate s c ates bei anus
Ondatra zibethicus
Neovison vison
Eriocheir sinensis
Alopochen aegyptiaca
Eichhornia crassipes
Lissorhoptrus brevirostris
Lissorhoptrus oryzophilus
Altern anthera phil oxeroi des
Baccharis halimifolia
Cyprinus carpio
Nymphaea mexicana
Lepomis gibbosus
Sander lucioperca
Callinectes sapidus
Orconectes limosus
Fundulus heteroc litus
Sinanodonta woodiana
Oncorhynchus mykiss
Perca fluviatilis
Batrachochytrium dendrobatidis
Gambusia holbrooki
Cyperus alterniflorus
Zantedeschia aethiopica
Sporobolus pumilus
Silurus glanis
Carassius auratus
Nymphaea sp.
Typha domingensis
Typha angustifolia
Salvinia natans
Graptemys pseudogeographica
Gyrodactylus salaris
Didemnum vexillum
Ludwigia spp.
Hydrocotyle ranunculoi des
Elodea c anadensis
Anguillicoloides crassus
Oxyura jamaicensis
Elodea nuttallii
Lagarosiphon major
Pacifas tacus lenius culus
Crassula helmsii
Branta canadensis
Myriophyllum aquaticum
Crepidula porcellana
Pseudoc hattonella verruculos a
Aphanomyces astac i
Pseudorasbora parva
Phoxinus phoxinus
Paralithodes camtschaticus
Cygnus olor
Sargassum muticum
Pomacea spp.
Azolla filiculoides
Castor canadensis
Caulerpa taxifolia
Rhinella marina
Cabomba caroliniana
Sporobolus anglicus
Salvinia spp.
Hymenachne spp.
Bubalus bubalis
Myocastor coypus
Micropterus salmoides
Trachemys scripta
Ludwigia grandiflora
Pistia stratiotes
Spartina spp.
Dikerogammarus villosus
Polypedates leucomystax
Chelydra serpentina
Lepomis macrochirus
Rudbeckia laciniata
Gymnocoronis spilanthoides
Balanus improvisus
Nymphoides peltata
Aeromonas salmonicida
Undaria pinnatfida
Didymosphenia geminata
Mnemiopsis leidyi
Salvinia molesta
Procambarus clarkii
Lagocephalus sceleratus
Cercopagis pengoi
Rhopilema nomadica
Portunus pelagicus
Costa Rica
Bangladesh/India/Pakistan/Sri Lanka
Belize Maldives
Dominican Republic
Burkina Faso Mali
Central African Republic
United Kingdom
South Africa
New Zealand
Sri Lanka
Fig. 5. Global network of aquatic invasive alien species costs per country. This bipartite network is composed of both species and country nodes. Links indicate the cumulative costs of
species in countries. The thicker the link, the higher the cost. Likewise, node size is proportional to the total cumulative cost, with a log spline. For species nodes, node size represents
the total cost they had over all countries. For country nodes, the node size represents the total cost of all species in that country.
Fig. 6. Fivemodelling techniques considering globalaquatic invasioncosts over time[ordinary leastsquares (OLS) regressions (a),robust regression(b), generalised additivemodel (GAM)
(c), multivariateadaptive regression splines(MARS) (d) and quantile regressions (e)].Points are annualtotal costs. Notethe scales differamong subplots. Shaded areasare 95% condence
intervals, and prediction intervals in the case of MARS. Root mean square error (RMSE) is shown for all appropriate models as well as 2020 cost predictions.
R.N. Cuthbert, Z. Pattison, N.G. Taylor et al. Science of the Total Environment 775 (2021) 145238
to 74% associated with terrestrial habitats (Fig. 8). Although in InvaCost
the number of aquatic species and the number of documents reporting
their costs constituted relatively similar percentages (20% and 28%,
respectively), the value of their reported cost comprised just 5% of the
global total. This increased to just 9% when considering only costs
reported from management strategies. If management expenditure
was unbiased between habitat types according to numbers of known
established aliens, we estimated that a further US$39 billion should
have been spent on aquatic species to date.
4. Discussion
Our study reveals that aquatic IAS have likely cost the global economy
at least US$345 billion. This estimate is probably highly conservative as it
only includes costs that have been documented and captured in the
InvaCost database. Moreover, the taxonomic, geographic, temporal and
habitat trends among these costs suggest that cost reporting is very un-
even, with many IAS and countries entirely lacking reported costs. Most
costs were attributed to aquatic invertebrates (US$214 billion), with
lower costs for vertebrates (US$97 billion) and plants (US$20 billion).
Our estimate of the costs of aquatic IAS globally in the year 2020 US
$23 billion, much higher in magnitude than the cost, for example, of man-
aging global marine protected areas (US$519 billion; Balmford et al.,
2004)calls for increased investments in management of IAS.
4.1. Cost distributions across taxa
Globally, mosquitoes are major contributors to the burden of
diseases, with vector-borne pathogens and parasites causing over one
billion infections and one million deaths annually (Kilpatrick and
Randolph, 2012;Campbell-Lendrum et al., 2015). The massive costs at-
tributed to vector-borne diseases from invasive mosquitoes are thus not
surprising, given the costs to healthcare systems worldwide. In Brazil,
for example, the government invested approximately US$48 million
per year from 2015 to 2017 for limiting population outbreaks of
A. aegypti (Bueno et al., 2017). In Columbia, total medical costs for the
treatment of dengue-infected patients reached US$3 billion between
2010 and 2012 (Rodríguez et al., 2015), and the recent chikungunya
outbreak cost about US$76 million to the healthcare system (Cardano
et al., 2015). Mosquitoes can also lead to economic losses associated
with recreation and tourism, as they discourage people from carrying
out certain activities or visiting certain sites (Claeys-Mekdade and
Morales, 2002). In the present study, damages to sectors such as health
comprised 73% of mosquito costs, with just 4% spent on management.
Future range expansions of invasive mosquitoes are expected to in-
crease their economic impact (Iwamura et al., 2020). Although mosqui-
toes vector diseases in their terrestrial-based adult life stage, where most
costs are incurred, larval and pupal life stages are invariably spent in
water where management is often targeted, with the characteristics
Fig. 7. Plotof the linear curve model givenby Eq. (3) (Supplementary Material1) against the cumulativecost data. Circularmarkers representall the data. Wecomputedbesttparameter
=335.1,K=26274,α= 0.22 and metric valuesr
= 0.996, RMSE=6.73. Square markers represent the adjusteddata set, which excludes four upperend extreme values(any
cost valuegreater than Q
+ 1.5 × IQR = US$14.66 billion,where Q
is the upperquartile and theIQR is the interquartile rangeof the dataset), i.e.(2003, US$25.06billion), (2005,US$21.07
billion),(2009, US$18.34billion) and (2011,US$52.61 billion),corresponding to timest= 43, 45, 49 and 51, respectively.We found that C
= 0.999 and
RMSE = 2.26. The shaded areas represent 95% condence regions indicating the range of predicted cumulative costs.
Fig. 8. Proportions of known established alien species, and with respect to InvaCost
estimates: numbers of species, documents, total costs and management costs between
terrestrial and aquatic habitats. Raw values are presented per habitat type; abbreviations:
b. = billion.
R.N. Cuthbert, Z. Pattison, N.G. Taylor et al. Science of the Total Environment 775 (2021) 145238
and distribution of aquatic habitat patches determining mosquito distri-
butions at various scales via key trait- and density-mediated processes
(Pintar et al., 2018;Cuthbert et al., 2019).
The Eurasian ruffe (G. cernua) was second most costly and has
caused declines of native sh by predation and competition, with con-
siderable economic impacts through reductions in commercially- and
recreationally-valuable sh species (Leigh, 1998). In turn, the zebra
and quagga mussels (Dreissena polymorpha and Dreissena bugensis)
are hyper-successful macrofouling freshwater bivalves, which are
highly costly to infrastructure through impeding navigation structures,
obstruction of water ow in pipes and occlusion of water lters
(Sousa et al., 2014). The coypu (M. coypus) has caused substantial eco-
nomic losses through agricultural impacts, as well as infrastructural
damage (Panzacchi et al., 2007). The primroses (Ludwigia spp.) are
known to reduce water quality that can affect economically important
taxa such as sh, and can be extremely costly to control (Williams
et al., 2010).
Costs attributed to invasive aquatic invertebrates such as the zebra
and quagga mussels were deemed highly reliable and mostly based on
empirical observations rather than extrapolations. In contrast, a large
share of vertebrate costs was potential costs, as in the case of the
three most costly vertebrate taxa, Eurasian ruffe G. cernua, coypu
M. coypus and American bullfrog L.catesbeianus. Therefore, realised ver-
tebrate costs require improved validation and reporting to the extent
possible from their actual invaded habitat. Similarly, reported costs of
plants, including the highly damaging Ludwigia species and broad-
leaved paper bark M. quinquenervia, were primarily potential costs,
not incurred at the time of estimation. Although ecological impacts of
aquatic plants have been well-studied by invasion scientists (Pyšek
et al., 2008;Gallardo et al., 2016), there is scope for more thorough re-
cording of realised economic impacts.
4.2. Cost distributions across geographic regions and types
The costs of aquatic IAS were also unevenly distributed across
geographic regions, with particularly high reported costs in North
America (US$166 billion) and Asia (US$45 billion). In turn, a substantial
proportion (26%) of the costs were unattributed to specic geographic
regions. Moreover, most costs were driven by damages (74%), whilst
management (principally control-related) costs were just 6%. It may
be expected that management costs are lower than damage or loss
costs: if the inverse were true, management would not be economically
justiable. However, the InvaCost search strategy may have exacerbated
this difference. Reports of management costs may have been dispropor-
tionately missed by the systematic literature searches because manage-
ment studies often do not mention costs, economics or other InvaCost
search terms (Diagne et al., 2020b) in their title, abstract or keywords
(e.g. Sandodden and Johnsen, 2010).
At the country scale, the USA exhibited both the highest magnitude
of costs and the greatest number of studies compared to all other coun-
tries. The high degree of cost reporting in the USA is unsurprising given
that early estimates of costs focused on this country (Pimentel et al.,
2000,Pimentel et al., 2005), which sparked research efforts to better
understand costs and provide a more rened spatial and temporal de-
scription for those costs. The USA also scores highly on several socio-
economic variables that have been found to correlate positively with re-
ported costs of IAS (Haubrock et al., 2021;Kourantidou et al., 2021),
such as GDP (1st in world), human population (3rd), international tour-
ism arrivals (3rd) and research expenditure (9th).
In contrast, the InvaCost database contains no aquatic IAS costs at all
for many countries, particularly in Asia and Africa. However, even in
countries such as South Africa, where research on biological invasion is
leading (van Wilgen et al., 2020), large gaps in our knowledge of eco-
nomic costs are evident. For example, South Africa is a global invasion
hotspot for freshwater sh and has been invaded by numerous inverte-
brate taxa in freshwater, estuarine and marine environments, with
well-known impacts on human wellbeing (Appleton et al., 2009;
Ellender and Weyl, 2014;Weyl et al., 2020;Robinson et al., 2020).
However, we captured no monetary costs for such taxa. Similarly,
in other African countries, IAS without formally documented or
quantied costs are known to affect human societies via impacts
to biological communities, local sheries and water storage infra-
structures (e.g. Nile perch in East Africa; Harris et al., 1995;Kwena
et al., 2012;Aloo et al., 2017,andcraysh in Lake Naivasha, Kenya;
Kafue River, Zambia; Madzivanzira et al., 2020). Limited cost
reporting in Africa and Asia is likely reective of a low priority
given to IAS research, or capabilities (Pyšek et al., 2008), despite
high levels of introduction via, for example, aquaculture (Lin
et al., 2015). However, there may have been some bias introduced
by the original InvaCost search string, as no currencies from these
continents were explicitly included as search terms (even if
searches were performed in 15 non-English languages, Angulo
et al., 2021).
Nonetheless, limited cost reporting in Africa and Asia is alarming
given that invasions in these countries may disproportionately impact
livelihoods, given high levels of poverty, limited resources for research
and management, and an overall limited preparedness to meet chal-
lenges brought by IAS (Early et al., 2016). Limited cost reporting also
hinders management actions, as the extent of IAS cost is not fully
realised by managers.
Network analyses additionally revealed a distinct lack of global
structuring of costs, whereby clustering appeared disparate across
taxa and countries, insinuating a largely random distribution of costs
and vast gaps in cost reporting of well-known aquatic IAS. That is, for
many countries, there was generally only one cluster, indicating unique
combinations of economic impacts associated with particular species,
despite some of these species being highly widespread. One example
of an exception to this is Aedes spp., which had a consistent and pan-
tropical impact, resulting in a distinct cost cluster. Nonetheless, other
context-dependencies, such as differences in climate and pathways,
likely also inuence IAS compositions.
4.3. Temporal trends in costs
The majority of tted models indicated exponentially increasing
annual costs of aquatic IAS since 1960 over several magnitudes, to a
best-t extrapolated annual global cost of US$23 billion in 2020.
Model differences in recent years likely reect differential sensitivities
to time lags in cost reporting. Model predictions of cost increases over
time align with increasing rates of biological invasions worldwide
(Seebens et al., 2017), as globalisation and intensication of trade and
transport networks result in high propagule and colonisation pressures
from novel source pools (Seebens et al., 2018). Given that invasion rates
will increase further in future (Seebens et al., 2020), we can expect fur-
ther increases in economic costs although investments in manage-
ment, especially prevention and rapid eradication, could limit realised
costs (Leung et al., 2002). Moreover, these results align with the nd-
ings of Bradshaw et al. (2016) who have suggested, specically for
invasive insects such as mosquitoes, that costs are generally largely
underestimated and are expected to increase through time. Our
mathematically-modelled density-impact curves also suggest that
costs of IAS to the global economy will continue to increase, as
they were far from an asymptotic plateau, even where extreme
values were removed and time lags not incorporated. Moreover,
this population-level approach does not account for unreported
costs or those arising from future IAS spread, and this likely results
in further underestimation.
4.4. Reporting of invasion costs of aquatic IAS compared to terrestrial IAS
Despite over one quarter of known alien species using aquatic envi-
ronments, only 5% of the total cost in the InvaCost database was
R.N. Cuthbert, Z. Pattison, N.G. Taylor et al. Science of the Total Environment 775 (2021) 145238
attributed to aquatic species. Further, the majority (54%) of these costs
were from semi-aquatic rather than fully aquatic species. On one
hand, this nding potentially reects a bias in cost reporting towards
terrestrial systems, in line with ecological research in general (Menge
et al., 2009;Richardson and Poloczanska, 2008). With respect to man-
agement costs of IAS, if investments of equivalent magnitude to terres-
trial were made for aquatic systems, one would anticipate a further US
$39 billion to have been spent to date. Note that this extrapolation
does not consider potentially lower costs in aquatic ecosystems (i.e.
less infrastructure to damage) or differences in management efcien-
cies between terrestrial and aquatic environments. On the other hand,
the disparity between aquatic and terrestrial costs may thus reect gen-
uinely lower costs of aquatic particularly marine IAS relative to ter-
restrial IAS. There are limited human assets and infrastructures in aquatic
systems, limiting the scope for easily-quantiable damages and resulting
in minimal investments in prevention and management. For example,
terrestrial agricultural practices are heavily impacted by crop pests
(Paini et al., 2016;Ahmed and Petrovskii, 2019), whereas agricultural ac-
tivities in aquatic systems (e.g. rice elds) are relatively scarce. However,
aquatic systems do offer highly valuable ecosystem services that could be
affected by IAS, such as aquaculture, and often through cascading effects
that are difcult to predict (Walsh et al., 2016). Thus, we encourage in-
vestment in management of IAS in aquatic systems to limit future costs
that stem from damage and loss (Leung et al., 2002).
5. Conclusions
Urgent and coordinated management actions are required globally to
reduce economic and ecological impacts from aquatic IAS. Whilst costs of
aquatic IAS are escalating, knowledge of impacts across major taxonomic
groupings, geographic regions and habitat types remains diffuse. These
knowledge gaps suggest costs of aquatic IAS are underestimated, partic-
ularly relative to their ecological impacts and to the more intensively-
studied terrestrial species. Equally, geographical biases in reported
costs highlight the need for increased and improved cost reporting,
given that allocation of nite resources to manage IAS is underpinned
by adequate understandings of costs. We urge our results to be applied
as an incentive for managers, stakeholders and scientists to increase
and improve cost reporting and invest in a more adequate protection
of aquatic ecosystems.
CRediT authorship contribution statement
Ross N. Cuthbert: Conceptualization, Data curation, Formal analysis,
Visualization, Writing - original draft, Writing - review & editing. Zarah
Pattison: Conceptualization, Data curation, Writing - review & editing.
Nigel G. Taylor: Conceptualization, Data curation, Writing - review &
editing. Laura Verbrugge: Conceptualization, Data curation, Writing -
review & editing. Christophe Diagne: Conceptualization, Data curation,
Writing - review & editing. Danish A. Ahmed: Conceptualization,
Formal analysis, Visualization, Writing - review & editing. Boris
Leroy: Conceptualization, Data curation, Formal analysis, Visualiza-
tion, Writing - review & editing. Elena Angulo: Conceptualization,
Data curation, Writing review & editing. Elizabeta Briski: Conceptu-
alization, Writing - review & editing. César Capinha: Conceptualization,
Writing - review & editing. Jane A. Catford: Conceptualization, Writing -
review & editing. Tatenda Dalu: Conceptualization, Writing - review &
editing. Franz Essl: Conceptualization, Writing - review & editing.
Rodolphe E. Gozlan: Conceptualization, Writing - review & editing.
Phillip J. Haubrock: Conceptualization, Writing - review & editing. Melina
Kourantidou: Conceptualization, Writing - review & editing. Andrew M.
Kramer: Conceptualization, Formal analysis, Visualization, Writing -
review & editing. David Renault: Conceptualization, Data curation,
Writing - review & editing. Ryan J. Wasserman: Conceptualization,
Writing - review & editing. Franck Courchamp: Conceptualization, Data
curation, Writing - review & editing.
Declaration of competing interest
The authors declare that they have no known competing nancial
interests or personal relationships that could have appeared to inu-
ence the work reported in this paper.
The authors acknowledge the French National Research Agency
(ANR-14-CE02-0021) and the BNP-Paribas Foundation Climate Initia-
tive for funding the InvaCost project that allowed the construction of
the InvaCost database. The present work was conducted following a
workshop funded by the AXA Research Fund Chair of Invasion Biology
and is part of the AlienScenarios project funded by BiodivERsA and
Belmont-Forum call 2018 on biodiversity scenarios. RNC is funded
through a Humboldt Research Fellowship from the Alexander von
Humboldt Foundation. DAA is funded by the Kuwait Foundation for
the Advancement of Sciences (KFAS) (PR1914SM-01) and the Gulf
University for Science and Technology (GUST) internal seed fund
(187092). CD was funded by the BiodivERsA-Belmont Forum Project
AlienScenarios (BMBF/PT DLR 01LC1807C). EA was funded by the AXA
Research Fund Chair of Invasion Biology of University Paris Saclay. CC
was supported by Portuguese National Funds through Fundação para a
Ciência e a Tecnologia (CEECIND/02037/2017; UIDB/00295/2020 and
UIDP/00295/2020). TD acknowledges funding from National Research
Foundation (NRF_ZA) (Grant Number: 117700). FE appreciates funding
by the Austrian Science Foundation (FWF project no I 4011-B32). AMK
was supported by the NSF Macrosystems Biology program under grant
1834548. DR thanks InEE-CNRS who supports the French national
network Biological Invasions (Groupement de Recherche InvaBio,
Appendix A. Supplementary material
Underlying data are publicly available in an online repository
( The dataset used for
analysis is provided in the Supplementary Material. Supplementary
data to this article can be found online at doi:
Ahmed, D.A., Petrovskii, S.V., 2019. Analysingthe impact of trap shape and movement be-
haviour of ground-dwelling arthropods on trap efciency. Methods Ecol. Evol. 10,
Aldridge, D.C., Oreska, M.P.J., 2011. Estimating the nancial costs of freshwater invasive
species in Great Britain: a standardized approach to invasive species costing. Biol. In-
vasions 13, 305319.
Aloo, P.A., Njiru, J., Balirwa, J.S., Nyamweya, C.S., 2017. Impacts of Nile perch, Lates
niloticus, introduction on the ecology, economy and conservation of Lake Victoria,
East Africa. Lakes Reserv. Res. Manag. 22, 320333.
Angulo, E., Diagne, C., Ballesteros-Mejia, L., Akulov, E.N., Dia, C.A.K.M., Adamjy, T., et al.,
2021. Non-English languages enrich scientic data: the example of the costs of bio-
logical invasions. Sci. Total Environ. (in press).
Appleton, C.C., Forbes, A.T., Demetriades, N.T., 2009. The occurrence, bionomics and po-
tential impacts of the invasive freshwater snail Tarebia granifera (Lamarck, 1822) in
South Africa. Zoölogische Medelingen 83, 525536.
Balmford,A., Gravestock, P., Hockley, N., McClean, C.J.,Roberts, C.M., 2004. The worldwide
costs of marine protected areas. Proc. Natl. Acad. Sci. 101, 96949697.
Blackburn,T.M., Bellard, C., Ricciardi, A., 2019. Alien versus native species as drivers of re-
cent extinctions. Front. Ecol. Environ. 17, 203207.
Bradshaw, C.J., Leroy, B., Bellard, C., Roiz, D., Albert, C., et al., 2016. Massive yet grossly
underestimated global costs of invasive insects. Nat. Commun. 7, 12986.
Bueno, C.C., Almeida, P.R., Retamero, A., Clark, L.G., 2017. Aedes aegypti: economic impact
of prevention versus palliation of diseases caused by the mosquito. Value Health 20,
Campbell-Lendrum,D., Manga, L., Bagayoko, M., Sommerfeld, J., 2015. Climatechange and
vector-borne diseases: what are the implications for public health research and pol-
icy? Philos. Trans. R. Soc. B 370, 20130552.
Capinha, C., Essl, F., Seebens, H., Moser, D., Pereira, H.M., 2015. The dispersal of alien spe-
cies redenes biogeography in the Anthropocene. Science 348, 12481251.
Cardano, J.A., Villamil-Gómez, W.E., Jimenez-Canizales, C.E., Castañeda-Hernández, D.M.,
Rodríguez-Morales, A.J., 2015. Estimating the burden of disease and the economic
R.N. Cuthbert, Z. Pattison, N.G. Taylor et al. Science of the Total Environment 775 (2021) 145238
cost attributable to chikungunya, Colombia, 2014. Tropical Medicine and Hygiene
109, 793802.
Claeys-Mekdade, C., Morales, A., 2002. Moustiques et démoustication: une enquête
sociologique auprès des Arlésiens et des Camarguais. Rapport nal de l'Etude
d'impact d'un éventuel traitement au B.t.i. sur le territoire du Parc naturel régional
de Camargue. DESMID-IMEP.
Crystal-Ornelas, R., Lockwood, J.L., 2020. The known unknownsof invasive species im-
pact measurement. Biol. Invasions 22, 15131525.
Cuthbert, R.N., Callaghan, A., Dick, J.T.A., 2019. A novel metric reveals biotic resistance po-
tential and informs predictions of invasion success. Sci. Rep. 9, 15314.
Cuthbert, R.N., Kotronaki, S.G., Dick, J.T.A., Briski, E., 2020. Salinit y tolerance and geo-
graphic origin predict global alien amphipod invasions. Biol. Lett. 16, 20200354.
Cuthbert, R.N., Bartlett, A.C., Turbelin, A., Haubrock, P.J., Diagne, C., et al., 2021. Economic
costs of biological invasions in the United Kingdom. NeoBiota (in press).
Darwall, W., Bremerich, V., De Wever, A., Dell, A.I., Freyhof, J., et al., 2018. The Alliance for
Freshwater Life: a global call to unite efforts for freshwater biodiversity science and
conservation. Aquat. Conserv. Mar. Freshwat. Ecosyst. 28, 10151022.
Diagne, C., Catford,J.A., Essl, F., Nuñez,M.A., Courchamp, F., 2020a. Whatare the economic
costs of biological invasions? A complex topic requiring international and interdisci-
plinary expertise. NeoBiota 63, 2537.
Diagne, C., Leroy, B., Gozlan, R.E.,Vaissiere, A.C., Assailly, C., etal., 2020b. InvaCost: a public
database of the economic costs of biological invasions worldwide. ScienticData7,
Dick, J.T.A., Laverty, C., Lennon, J.J., Barrios-ONeill, D., Mensink, P.J., et al., 2017. Invader
Relative Impact Potential: a new metric to understand and predict the ecological im-
pacts of existing, emerging and future invasive alien species. J. Appl. Ecol. 54,
Early, R., Bradley, B., Dukes, J., Lawler, J.J., Olden, J.D., et al., 2016. Global threats from inva-
sive alien species in the twenty-rst century and national response capacities. Nat.
Commun. 7, 12485.
Ellender, B.R., Weyl, O.L.F., 2014. A review of current knowledge, risk and ecological im-
pacts associated with non-native freshwater sh introductions in South Africa.
Aquat. Invasions 9, 117132.
Fournier, A., Penone, C., Pennino, M.G., Courchamp, F., 2019. Predicting future invaders
and future invasions. Proc. Natl. Acad. Sci. 116, 79057910.
Gallardo, B., Clavero, M., Sánchez, M.I., Vilà,M., 2016. Global ecological impacts of invasive
species in aquatic ecosystems. Glob. Chang. Biol. 22, 151163.
Hanley, N., Roberts, M., 2019. The economic benets of invasive species management.
People and Nature 1, 124137.
Harris, C.K., Wiley, D.S., Wilson, D.C., 1995. Socioeconomic impacts of introduced species
in Lake Victoriasheries. In: Pitcher, T.J., Hart, P.J.B. (Eds.), Impact ofSpecies Changes
in African Lakes. Chapman and Hall, London.
Haubrock, P.J., Turbelin, A.J., Cuthbert, R.N., Novoa, A., Angulo, E., et al., 2021. Economic
costs of invasive alien species across Europe. NeoBiota (in press).
Iwamura, T., Guzman-Holst, A., Murray, K.A., 2020. Accelerating invasion potential of dis-
ease vector Aedes aegypti under climate change. Nat. Commun. 11, 2130.
Jackson, M.C., Wasserman, R.J., Grey, J., Ricciardi, A., Dick, J.T.A., et al., 2017. Novel and
disrupted trophic links following invasion in freshwater ecosystems. Adv. Ecol. Res.
57, 5597.
Katsanevakis, S., Wallentinus, I., Zenetos, A., Leppäkoski, E., Çinar, M.E., et al., 2014. Im-
pacts of invasive alien marine species on ecosystem services and biodiversity: a
pan-European review. Aquat. Invasions 9, 391423.
Kettunen, M., Genovesi, P., Gollasch, S., Pagad,S., Starnger, U., et al., 2009. Technical Sup-
port to EU Strategy on Invasive Alien Species (IAS). Institute for European Environ-
mental Policy (IEEP), Brussels, p. 44.
Kilpatrick, A.M., Randolph, S.E., 2012. Drivers, dynamics, and control of emerging vector-
borne zoonotic diseases. Lancet 380, 19461955.
van Kleunen,M., Xu, X., Yang, Q., Maurel, N., Zhang, Z., et al., 2020. Economic use of plants
is key to their naturalization success. Nat. Commun. 11, 3201.
Kourantidou, M., Cuthbert, R.N., Haubrock, P.J., Novoa, A., Taylor, N.G., et al., 2021. Eco-
nomic costs ofinvasive alien species in the Mediterranean basin. NeoBiota (in press).
Kumschick, S., Gaertner, M., Vilà, M., Essl, F., Jeschke, J.M., et al., 2015. Ecological impacts
of alien species: quantication, scope, caveats, and recommendations. BioScience 65,
Kwena, Z.A.,Bukusi, E., Omondi, E.,Ngayo, M., Holmes,K.K., 2012. Transactional sex in the
shing communities along Lake Victoria, Kenya: a catalyst for the spread of HIV. Afr.
J. AIDS Res. 11, 915.
Leigh, P., 1998. Benets and costs of the ruffe control program forthe Great Lakes shery.
J. Great Lakes Res. 24, 351360.
Leroy, B., Kramer, A., Vaissière, A.-C., Courchamp, F., Diagne, C., 2020. Analysing global
economic costs of invasive alien species with the invacost R package. biorXiv
Leung, B., Lodge, D.M., Finnoff, D., Shogren, J.F., Lewis, M.A., et al., 2002. An ounce of pre-
vention or a poundof cure: bioeconomic risk analysis of invasive species. Proc. R. Soc.
B Biol. Sci. 269, 24072413.
Lin, Y.P.,Gao, Z.X., Zhan, A.B.,2015. Introduction and use of nonnativespecies for aquacul-
ture in China: status, risks and management solutions. Rev. Aquac. 7, 2858.
Lovell, S.J., Stone, S.F., Fernandez, L., 2006. The economic impacts of aquatic invasive spe-
cies: a review of the literature. Agricultural and Resource Economics Review 35,
Madzivanzira, T.C., South, J., Wood, L.E., Nunes, A.L., Weyl, O.L.F., 2020. A review of fresh-
water craysh introductions in Africa. Reviews in Fisheries Science and Aquaculture.
(in press).
McGeoch, M.A., Jetz, W., 2019. Measure and reduce the harm caused by biological inva-
sions. One Earth 1, 171174.
McGeoch, M.A., Genovesi, P., Bellingham, P.J., Costello,M.J., McGrannachan,C., et al., 2015.
Prioritizing species, pathways, and sites to achieve conservationtargets for biological
invasion. Biol. Invasions 18, 299314.
Menge, B.A., Chan, F., Dudas, S., Eerkes-Medrano, D., Grorud-Colvert, K., et al., 2009. Ter-
restrial ecologists ignore aquatic literature: asymmetry in citation breadth in ecolog-
ical publications and implications for generality and progress in ecology. J. Exp. Mar.
Biol. Ecol. 377, 93100.
Mollot, G., Pantel, J.H., Romanuk, T.N., 2017. Chapter two - the effects of invasive species
on the decline in species richness: a global meta-analysis. Adv. Ecol. Res. 56, 6183.
Paini, D.R., Sheppard,A.W., Cook, D.C.,De Barro, P.J., Worner, S.P., etal., 2016. Global threat
to agriculture from invasive species. Proc. Natl. Acad. Sci. 113, 75757579.
Panzacchi, M., Cocchi, R., Genovesi, P., Bertolini, S., 2007. Population control of coypu
Myocastor coypus in Italy compared to eradication in UK: a cost-benet analysis.
Wildl. Biol. 13, 159171.
Pejchar, L., Mooney, H.A., 2009. Invasive species, ecosystem services and human well-
being. Trends Ecol. Evol. 24, 497504.
Pimentel, D., Lach, L., Zuniga, R., Morrison, D., 2000. Environmental and economic costs of
nonindigenous species in the United States. BioScience 50, 5366.
Pimentel, D., Zuniga, R., Morrison, D., 2005. Update on the environmental and economiccosts
associated with alien-invasive species in the United States. Ecol. Econ. 52, 273288.
Pintar, M.R., Bohenek, J.R., Eveland, L.L., Restarits Jr., W.J., 2018. Colonization across gradi-
ents of risk and reward: nutrients and predators generate species-specic responses
among aquatic insects. Funct. Ecol. 32, 15891598.
Poulin, M., Natacha, F., Line, R., 2011. Restoration of pool margin communities in cutover
peatlands. Aquat. Bot. 94, 107111.
Pyšek, P., Richardson, D.M., Pergl, J., Jarošík, V., Weber, E., 2008. Geographical and taxo-
nomic biases in invasion ecology. Trends Ecol. Evol. 23, 237244.
Pyšek, P., Hulme, P.E., Simberloff, D., Bacher, S., Blackburn, T.M., et al., 2020. Scientists
warning on invasive alien species. Biol. Rev. 95, 15111534.
R Core Team, 2020. R: A Language and Environment for Statistical Computing. R Founda-
tion for Statistical Computing, Vienna.
Ricciardi, A., MacIsaac, H.J., 2011. Impacts of biological invasions on freshwater ecosys-
tems. In:Richardson, D.M. (Ed.), Fifty Years of Invasion Ecology:The Legacy of Charles
Elton, 1st Wiley-Blackwell, Chichester.
Richardson, A.J., Poloczanska, E.S., 2008. Under-resourced, under threat. Science 320,
Robinson, T.B., Peters, K., Brooker, B., 2020. Coastal invasions: The South African context.
In: van Wilgen, B.W., Measey, J., Richardson,D.M., Wilson, J.R.,Zengeya, T.A. (Eds.), Bi-
ological Invasions in South Africa. Springer, Berlin.
Rodríguez, P.C., Galera-Galvez, K.,Yescas, J.G.L., Rueda-Gallardo,J.A., 2015. Costs of dengue
to the health system and individuals in Colombia from 2010 to 2012. Am. J. Trop.
Med. Hyg. 9, 709714.
Sandodden, R., Johnsen, S.I., 2010. Eradication of introduced signal craysh Pasifastacus
leniusculus using the pharmaceutical BETAMAX VET.®. Aquat. Invasions 5, 7581.
Seebens,H., Blackburn, T.M.,Dyer, E.E., Genovesi, P., Hulme,P.E., et al., 2017. No saturation
in the accumulation of alien species worldwide. Nat. Commun. 8, 14435.
Seebens, H., Blackburn, T.M., Dyer,E.E., Genovesi, P., Hulme, P.E., etal., 2018. Global rise in
emerging alien species results from increased accessibility of new source pools. Proc.
Natl. Acad. Sci. 115, E2264E2273.
Seebens, H., Bacher, S., Blackburn, T.M., Capinha, C., Dawson, W., et al., 2020. Projecting the
continental accumulation of alien species through to 2050. Glob. Chang. Biol. (in press).
Shabani, F., Ahmadi, M., Kumar, L., Sohljouy-fard, S., Tehrany, M.S., et al., 2020. Invasive
weed speciesthreats to global biodiversity: future scenarios of changes in the num-
ber of invasive species in a changing climate. Ecol. Indic. 116, 106436.
Sousa, R., Novais, A., Costa, R., Strayer, D.L., 2014. Invasive bivalves in fresh waters: im-
pacts from individuals to ecosystems and possible control strategies. Hydrobiologia
735, 233251.
Spatz, D.R., Zilliacus, K.M., Holmes, N.D., Butchart, S.H.M., Genovesi, P., et al., 2017. Glob-
ally threatened vertebrates on islands with invasive species. Sci. Adv. 3, e1603080.
Strayer, D.L., Findlay, S.E., 2010. Ecology of freshwater shore zo nes. Aquat. Sci. 72,
Turbelin,A.J., Malamud, B.D.,Francis, R.A., 2017.Mapping the global state of invasive alien
species: patterns of invasion and policy responses. Glob. Ecol. Biogeogr. 26, 7892.
UNEP, 2011. TheStrategic Plan for Biodiversity 20112020 and the Aichi Biodiversity Tar-
gets. COP CBD Tenth Meeting UNEP/CBD/COP/DEC/X/2. Nagoya.
Vanbergen, A.J., the Insect Pollinators Initiative, 2013. Threats to an ecosystem service:
pressures on pollinators. Front. Ecol. Environ. 11, 251259.
Vitousek, P.M., Dantonio, C.M., Loope, L.L., Rejmanek, M., Westbrooks, R., 1997. Intro-
duced species: a signicant component of human-caused global change. N. Z.
J. Ecol. 21, 116.
Walsh, J.R.,Carpenter, S.R., Zanden, M.J.V., 2016. Invasive species triggers a massiveloss of
ecosystem services through a trophic cascade. Proc. Natl. Acad. Sci. 113, 40814085.
Weyl, O.L.F., Ellender,B.R., Wasserman,R.J., Truter, M., Dalu,T., et al., 2020. Alien Freshwa-
ter Fauna in South Africa. In: van Wilgen, B.W., Measey, J., Richardson, D.M., Wilson,
J.R., Zengeya, T.A. (Eds.), Biological Invasions in South Africa. Springer, Berlin.
van Wilgen, B., Measey, J., Richardon, D.M., Wilson, J.R., Zengeya, T.A., 2020. Biological In-
vasions in South Africa. Springer, Berlin.
Williams, F., Eschen, R., Harris, A., Djeddour, D., Pratt, C., et al., 2010. The EconomicCost of
Invasive Non-native Species to Great Britain. CABI, Egham, Egham.
Woodward, G., Perkins, D.M., Brown, L.E., 2010. Climate change and freshwater ecosys-
tems: impacts across multiple levels of organization. Philosophical Transactions of
the Royal Society B: Biological Sciences 365, 20932106.
Yokomizo, H., Possingham, H., Thomas, M., Buckley, Y., 2009. Managing the impact of in-
vasive species: the value of knowing the density-impact curve. Ecol. Appl. 19,
R.N. Cuthbert, Z. Pattison, N.G. Taylor et al. Science of the Total Environment 775 (2021) 145238
... The pathogens they bear include arthropod-borne viruses-also called arboviruses, belonging to the Flaviviridae, Togaviridae, Reoviridae and Bunyaviridae families-which are responsible for numerous widely distributed illnesses, such as dengue, yellow fever, chikungunya, Zika and West Nile viruses [1]. As such, they give rise to major ecological, economic and health problems worldwide [2][3][4] and require significant management and surveillance efforts (also see Box 1). In parallel, the world's economic growth and intensification of international trade and travel exacerbate these threats by promoting the emergence of vector-borne diseases [5,6]. ...
... In turn, relationships between economic measures-such as GDP, international trade or research effort-and the economic impact of biological invasions have been reported [15][16][17]. Often, invasive alien species have tremendous costs to national economies [18][19][20][21]; this is particularly true for invasive hematophagous arthropods, which are sources of extremely high healthcare costs [4]. Recent assessments estimated that the economic cost of invasive alien species reached at least US$ 2.168 trillion over the last 4 decades (see Living Figure in [22], and https:// boris leroy. ...
... While the costs in terms of human lives and suffering should be sufficient to warrant effective measures against the spread of hematophagous insects and the pathogens they carry [115], it is in fact the huge economic costs incurred by the spread of hematophagous insects that ironically provide powerful and more tangible metrics for actions by international authorities. Economic costs therefore appear to be more straightforward to use for synthetic and applied purposes, and especially in the context of invasive alien species [20], including hematophagous arthropods [4,23]. ...
Full-text available
Biological invasions have increased significantly with the tremendous growth of international trade and transport. Hematophagous arthropods can be vectors of infectious and potentially lethal pathogens and parasites, thus constituting a growing threat to humans—especially when associated with biological invasions. Today, several major vector-borne diseases, currently described as emerging or re-emerging, are expanding in a world dominated by climate change, land-use change and intensive transportation of humans and goods. In this review, we retrace the historical trajectory of these invasions to better understand their ecological, physiological and genetic drivers and their impacts on ecosystems and human health. We also discuss arthropod management strategies to mitigate future risks by harnessing ecology, public health, economics and social-ethnological considerations. Trade and transport of goods and materials, including vertebrate introductions and worn tires, have historically been important introduction pathways for the most prominent invasive hematophagous arthropods, but sources and pathways are likely to diversify with future globalization. Burgeoning urbanization, climate change and the urban heat island effect are likely to interact to favor invasive hematophagous arthropods and the diseases they can vector. To mitigate future invasions of hematophagous arthropods and novel disease outbreaks, stronger preventative monitoring and transboundary surveillance measures are urgently required. Proactive approaches, such as the use of monitoring and increased engagement in citizen science, would reduce epidemiological and ecological risks and could save millions of lives and billions of dollars spent on arthropod control and disease management. Last, our capacities to manage invasive hematophagous arthropods in a sustainable way for worldwide ecosystems can be improved by promoting interactions among experts of the health sector, stakeholders in environmental issues and policymakers (e.g. the One Health approach) while considering wider social perceptions. Graphical abstract
... This reflects the large volumes of trade involving those areas (Stranga & Katsanevakis, 2021), but also the greater surveillance and detection work done by these more affluent countries (Seebens et al., 2013). In countries with less well-funded surveillance systems, real invasion rates could be markedly higher than detected Cuthbert et al., 2021). At larger geographic scales, the most endangered ecoregions include the central Indo-Pacific, North-west Pacific, the Mediterranean and the North-west Atlantic -all because they combine a central role in world trade and short distances (environmentally-speaking) to adjacent ecoregions. ...
... Invasive species are a leading global threat to biodiversity and pose a severe risk to current and future food security and livelihoods, particularly in countries without the capabilities to prevent and manage these invasions. The ecological and economic costs of invasive species are escalating rapidly (Cuthbert et al., 2021) and are now believed (across all realms) to be in the trillions of dollars (Cuthbert et al., 2022). International trade is a direct driver of biological invasions worldwide (Hulme, 2021). ...
Technical Report
Full-text available
Impacts of global shipping on climate, human health and the ocean.
... The spread of Non-Indigenous Species (NIS) is an increasing global phenomenon [1][2][3]. Invasive Alien Species (IAS) is a sub-group of NIS that can have significant detrimental effects on biodiversity, ecosystem services, and economies [4,5]. In response to this, several studies have been conducted in recent years to gather baseline data on NIS and IAS in Irish marine and terrestrial environments. ...
Full-text available
Documenting temporal and spatial occurrence trends of Non-Indigenous Species (NIS) is essential to understand vectors and pathways of introduction, and for horizon scanning for future introductions. This study provides an overview of marine NIS found in the Republic of Ireland up to 2020. Taxonomic groups, species origin, and location of first reporting (counties) were compiled and analysed focusing on the last three decades. While the unambiguous characterisation of introduction events is challenging, analysis of 110 species corroborated the global weight of evidence that shipping activities to/from ports and marinas are the most likely vectors and pathways in Ireland. A comparable review study for the Netherlands revealed that most NIS were first introduced to mainland Europe and subsequently would take on average >15 years to reach Ireland. In the last two decades there has been an increase in NIS-focused surveys in Ireland. Incorporating data from these surveys in centralized national repositories such as the National Biodiversity Data Centre, will strongly aid the evaluation of potential NIS management responses. Furthermore, the availability of robust baseline data as well as predictions of future invaders and their associated vectors and pathways will facilitate the effective application of emerging monitoring technologies such as DNA-based approaches.
... When non-native species arrive and become established in new areas, there are often environmental and/or economic costs associated with the impacts of the species and the resulting management needs [1][2][3]. In addition, biological invasions are considered a major threat to natural systems and a key cause of biodiversity loss worldwide [4,5]. ...
Full-text available
Predicting the likelihood that non-native species will be introduced into new areas remains one of conservation’s greatest challenges and, consequently, it is necessary to adopt adequate management measures to mitigate the effects of future biological invasions. At present, not much information is available on the areas in which non-native aquatic plant species could establish themselves in the Iberian Peninsula. Species distribution models were used to predict the potential invasion risk of (1) non-native aquatic plant species already established in the peninsula (32 species) and (2) those with the potential to invade the peninsula (40 species). The results revealed that the Iberian Peninsula contains a number of areas capable of hosting non-native aquatic plant species. Areas under anthropogenic pressure are at the greatest risk of invasion, and the variable most related to invasion risk is temperature. The results of this work were used to create the Invasion Risk Atlas for Alien Aquatic Plants in the Iberian Peninsula, a novel online resource that provides information about the potential distribution of non-native aquatic plant species. The atlas and this article are intended to serve as reference tools for the development of public policies, management regimes, and control strategies aimed at the prevention, mitigation, and eradication of non-native aquatic plant species.
... Economic costs or losses are associated with impacts on commercial and recreational fisheries in terms of damage to fishing gear, increased labor demand, and predation of commercial fisheries target species (Cuthbert et al., 2021). Etrumeus golanii does not appear to be costly to commercial fisheries as it does not damage fishing gear, injure personnel, or cause a reduction in native fish stocks (Tamsouri et al., 2019), yet fishers in Greece consider that it reduces the overall economic turnover of the catches due to its high abundances and the low commercial price as there is a minimal market demand (Karachle, personal communication). ...
Full-text available
Greek waters are the recipient of several alien species, mainly through natural dispersal following invasion and establishment of non-indigenous species (NIS) in neighbouring areas, making their monitoring and mitigating their effects of paramount importance. The European Union legislation framework toward alien species invasions, considers risk assessments as the top of the spear for a first assessment of NIS and their potential to become invasive or not. The Union List has already included top priority species, among which very few marine. Golani's round herring (Etrumeus golanii) is a species of round herrings in the family Dussumieriidae, a Lessepsian migrant and belonging to a group of NIS in the Mediterranean basin which are less studied . Its distribution range is mainly limited in southeastern Mediterranean Sea, while in the Greek Seas it has not yet been observed in the north Aegean and Ionian seas, probably due to temperature and oceanographical reasons. Its presence in the basin is recorded by commercial fisheries landings in several countries (especially purse-seiners), indicating a potentially positive effect on commercial fisheries. A risk assessment of E. golanii in Greek waters was carried out in this work, based on the Risk Assessment Scheme developed by the GB Non-Native Species Secretariat (GB Non-Native Risk Assessment -GBNNRA). An overall semi-quantitative summary of risk, in terms of likelihood of events and magnitude of impacts was facilitated for several attributors, including confidence levels for each one. The assessment highlighted a very likely possibility of introduction in the Greek seas from neighbouring countries, as well as successful establishments of populations with high confidence levels. A moderate magnitude of impact regarding its further spread was deemed, while a minor one was indicated in terms of native species pressure and a minimal one in terms of economic costs and public health. Overall, E. golanii was not characterised as an invasive species (IAS) and local communities could benefit from its presence (commercial fisheries), however further studies focusing on its reproduction and spawning grounds should be implemented.
... Major challenges include a continuous rise in the number of IAS globally and their increasing rate of spread, with only a small proportion currently being managed (Hulme, 2009;Brunel et al., 2013;Cuthbert et al., 2021;Bang et al., 2022;Britton et al., 2023;) and in some countries, such as South Africa there are funding insecurities in public institutions responsible for conservation of nature (Gaertner et al., 2017). It is therefore crucial to interrogate how decisions about prioritising the management of IAS and areas under invasion are being informed to optimise investments (Kumschick et al., 2012). ...
Full-text available
Invasive alien species (IAS) pose global threat to economies and biodiversity. With rising number of species and limited resources, IAS management must be prioritised; yet agreed tools to assist decision–making and their application are currently inadequate. There is need for simple decision support tools (DST) that guide stakeholders to optimise investment based on objective and quantifiable criteria. This paper reviews DSTs for IAS management to assess their availability and application of principles of robust decision–making. The aim is to provide guidance towards adopting the principles of robust decision–making to improve applicability and practical use of DST. A literature search conducted to identify relevant studies that report on DST in biological invasion. Results indicate an increase in availability of DST; however, available studies are largely biased in geographical, habitat and taxonomic focus. The results also show challenges in practical use of existing tools as most of them do not apply principles of robust decision–making. Application of these principles has the potential to overcome weakness of the current decision–making process and as such, enable decision–makers to efficiently allocate resources towards IAS management. A call is made for more consideration and adoption of principles of robust decision–making when developing DST for IAS invasions.
... Their negative effects include alteration or loss of ecosystem services (Charles & Dukes, 2008), disrupted food webs (David et al., 2017), and lost productivity for agriculture (Paini et al., 2016), fisheries (Lovell et al., 2006), wildlife (Usher, 1986), and forestry (Holmes et al., 2009). Aquatic invasive species (AIS) alone are responsible for at least US $23 billion in global damages annually (Cuthbert et al., 2021), and invasive species threaten many native species with extinction (McGeoch et al., 2010;Tilman et al., 2017). ...
Full-text available
Aquatic invasive species (AIS) present major ecological and economic challenges globally, endangering ecosystems and human livelihoods. Managers and policy makers thus need tools to predict invasion risk and prioritize species and areas of concern, and they often use native range climate matching to determine whether a species could persist in a new location. However, climate matching for AIS often relies on air temperature rather than water temperature due to a lack of global water temperature data layers, and predictive power of models is seldom evaluated. We developed 12 global lake (water) temperature-derived "BioLake" bioclimatic layers for distribution modeling of aquatic species and compared "climatch" climate matching predictions (from climatchR package) from BioLake with those based on BioClim temperature layers and with a null model. We did this for 73 established AIS in the United States, training the models on their ranges outside of the United States and Canada. Models using either set of climate layers outperformed the null expectation by a similar (but modest) amount on average, but some species were occasionally found in locations with low climatch scores. Mean US climatch scores were higher for most species when using air temperature. Including additional climate layers in models reduced mean climatch scores, indicating that commonly used climatch score thresholds are not absolute but can be context specific and may require calibration based upon climate data used. Although finer resolution global lake temperature data would likely improve predictions, our BioLake layers provide a starting point for aquatic species distribution modeling. Climate matching was most effective for some species that originated at low latitudes or had small ranges. Climatch scores remain useful but limited for predicting AIS risk, perhaps because current ranges seldom fully reflect climatic tolerances (fundamental niches). Managers could consider climate matching as one of a suite of tools that can be used in AIS prioritization.
... Biological invasions are a major threat to biodiversity worldwide [1] and are identified as one of the main pressures on ecological values [2]. The expansion of aquatic Invasive Alien Plant Species (hereafter aIAPS) triggers complex and cumulative impacts on native biodiversity [3], human health [4], economic activities [5], and an overall decrease in ecosystem services and nature contributions to people [6]. Although the impacts of aIAPS work can be applied to perform pixel-based supervised classification through an ensemble approach, "classifier fusion" [29]. ...
Full-text available
Freshwater ecosystems host high levels of biodiversity but are also highly vulnerable to biological invasions. Aquatic Invasive Alien Plant Species (aIAPS) can cause detrimental effects on freshwater ecosystems and their services to society, raising challenges to decision-makers regarding their correct management. Spatially and temporally explicit information on the occurrence of aIAPS in dynamic freshwater systems is essential to implement efficient regional and local action plans. The use of unmanned aerial vehicle imagery synchronized with free Sentinel-2 multispectral data allied with classifier fusion techniques may support more efficient monitoring actions for non-stationary aIAPS. Here, we explore the advantages of such a novel approach for mapping the invasive water-hyacinth (Eichhornia crassipes) in the Cávado River (northern Portugal). Invaded and non-invaded areas were used to explore the evolution of spectral attributes of Eichhornia crassipes through a time series (processed by a super-resolution algorithm) that covers March 2021 to February 2022 and to build an occurrence dataset (presence or absence). Analysis of the spectral behavior throughout the year allowed the detection of spectral regions with greater capacity to distinguish the target plant from the surrounding environment. Classifier fusion techniques were implemented in the biomod2 predictive modelling package and fed with selected spectral regions to firstly extract a spectral signature from the synchronized day and secondly to identify pixels with similar reflectance values over time. Predictions from statistical and machine-learning algorithms were ensembled to map invaded spaces across the whole study area during all seasons with classifications attaining high accuracy values (True Skill Statistic, TSS: 0.932; Area Under the Receiver Operating Curve, ROC: 0.992; Kappa: 0.826). Our results provide evidence of the potential of our approach to mapping plant invaders in dynamic freshwater systems over time, applicable in the assessment of the success of control actions as well as in the implementation of long-term strategic monitoring.
Detection of early life stages of fishes is important for understanding life history patterns and critical spawning habitats. When feasible, identifying early life stages of fishes using morphology requires taxonomic expertise and can be challenging, time consuming, and imprecise. In this study, we used DNA metabarcoding to identify egg and larval batch samples from two sites in the species-rich East Sydenham River, Ontario, Canada. We used a two-step PCR metabarcoding approach to amplify a highly variable region of the mitochondrial COI gene from 1075 mixed species batch samples. Amplicon libraries were sequenced with Illumina Mi-seq and the sequencing reads were filtered and assembled using the software package mothur. Barcodes were then classified using a reference library comprised of Great Lakes fishes and potential invaders. In total, 34 species, including three at-risk species and three invasive species, were detected at the two sampling sites. This study shows the potential utility of metabarcoding for detection and identification of early life stage Great Lake fishes.
Full-text available
The reported costs of invasive alien species from the global database InvaCost are heterogeneous and cover different spatio‐temporal scales. A standard procedure for aggregating invasive species cost estimates is necessary to ensure the repeatability and comparativeness of studies. We introduce here the invacost r package, an open‐source software designed to query and analyse the InvaCost database. We illustrate this package and its framework with cost data associated with invasive alien invertebrates. First, the invacost package provides updates of this dynamic database directly in the analytical environment R. Second, it helps understand the heterogeneous nature of monetary cost data for invasive species, processes to harmonize the data and the inherent biases associated with such data. Third, it readily provides complementary methods to investigate the costs of invasive species at different scales, all the while accounting for econometric statistical issues. This tool will be useful for scientists working on invasive alien species, by (a) facilitating access to and use of this multi‐disciplinary data resource and (b) providing a standard procedure which will facilitate reproducibility and comparability among studies, one of the major critics of this topic until now. It should facilitate further interdisciplinary works including economists and invasion ecology researchers.
Full-text available
This review summarizes and analyses information on freshwater crayfish introductions in Africa. A total of 136 research papers and reports were found to be relevant. Forty-eight percent reported presence; 21% described negative impacts; 11% referred to potential socio-economic benefits; 9% evaluated control measures; 6% documented co-introduced parasites. Out of nine introduced crayfish species, five species Astacus astacus, Cherax quadricarinatus, Faxonius limosus, Procambarus clarkii, and Procambarus virginalis have established populations in the wild. Astacus astacus and F. limosus are present only in Morocco and P. virginalis is limited to Madagascar. Cherax quadricarinatus and P. clarkii have established populations in five and six countries, respectively. The main driver of crayfish introductions was to provide socio-economic benefits through aquaculture and fisheries development but there is limited evidence of success. Prevailing negative socio-economic impacts are linked to damage to agricultural water infrastructure, damage to fishing gear and declining fisheries performance. Ecological impacts pertain to direct and multi-trophic consumptive effects as well as indirect competitive effects primarily upon macro-invertebrates and potential spillover of parasites to other decapods. Research priorities are determining abundance, distribution and spread of crayfishes and assessing ecological impact to inform management decisions.
Full-text available
Invasive alien species (IAS) negatively impact the environment and undermine human well-being, often resulting in considerable economic costs. The Mediterranean basin is a culturally, socially and economically diverse region, harbouring many IAS that threaten economic and societal integrity in multiple ways. This paper is the first attempt to collectively quantify the reported economic costs of IAS in the Mediterranean basin, across a range of taxonomic, temporal and spatial descriptors. We identify correlates of costs from invasion damages and management expenditures among key socioeconomic variables, and determine network structures that link countries and invasive taxonomic groups. The total reported invasion costs in the Mediterranean basin amounted to $27.3 billion, or $3.6 billion when only realised costs were considered, and were found to have occurred over the last three decades. Our understanding of costs of invasions in the Mediterranean was largely limited to a few, primarily western European countries and to terrestrial ecosystems, despite the known presence of numerous high-impact aquatic invasive taxa. The vast majority of costs were attributed to damages or losses from invasions ($25.2 billion) and were mostly driven by France, Spain and to a lesser extent Italy and Libya, with significantly fewer costs attributed to management expenditure ($1.7 billion). Overall, invasion costs increased through time, with average annual costs between 1990 and 2017 estimated at $975.5 million. The lack of information from a large proportion of Mediterranean countries, reflected in the spatial and taxonomic connectivity analysis and the relationship of costs with socioeconomic variables, highlights the limits of the available data and the research effort needed to improve a collective understanding of the different facets of the costs of biological invasions. Our analysis of the reported costs associated with invasions in the Mediterranean sheds light on key knowledge gaps and provides a baseline for a Mediterranean-centric approach towards building policies and designing coordinated responses. In turn, these could help reach socially desirable outcomes and efficient use of resources invested in invasive species research and management.
Full-text available
Biological invasions continue to threaten the stability of ecosystems and societies that are dependent on their services. Whilst the ecological impacts of invasive alien species (IAS) have been widely reported in recent decades, there remains a paucity of information concerning their economic impacts. Europe has strong trade and transport links with the rest of the world, facilitating hundreds of IAS incursions, and largely centralised decision-making frameworks. The present study is the first comprehensive and detailed effort that quantifies the costs of IAS collectively across European countries and examines temporal trends in these data. In addition, the distributions of costs across countries, socioeconomic sectors and taxonomic groups are examined, as are socio-economic correlates of management and damage costs. Total costs of IAS in Europe summed to US$140.20 billion (or €116.61 billion) between 1960 and 2020, with the majority (60%) being damage-related and impacting multiple sectors. Costs were also geographically widespread but dominated by impacts in large western and central European countries, i.e. the UK, Spain, France, and Germany. Human population size, land area, GDP, and tourism were significant predictors of invasion costs, with management costs additionally predicted by numbers of introduced species, research effort and trade. Temporally, invasion costs have increased exponentially through time, with up to US$23.58 billion (€19.64 billion) in 2013, and US$139.56 billion (€116.24 billion) in impacts extrapolated in 2020. Importantly, although these costs are substantial, there remain knowledge gaps on several geographic and taxonomic scales, indicating that these costs are severely underestimated. We, thus, urge increased and improved cost reporting for economic impacts of IAS and coordinated international action to prevent further spread and mitigate impacts of IAS populations.
Full-text available
Although the high costs of invasion are frequently cited and are a key motivation for environmental management and policy, synthesised data on invasion costs are scarce. Here, we quantify and examine the monetary costs of biological invasions in the United Kingdom (UK) using a global synthesis of reported invasion costs. Invasive alien species have cost the UK economy between US$6.9 billion and $17.6 billion (£5.4 – £13.7 billion) in reported losses and expenses since 1976. Most costs were reported for the entire UK or Great Britain (97%); country-scale cost reporting for the UK's four constituent countries was scarce. Reports of animal invasions were the costliest ($4.7 billion), then plant ($1.3 billion) and fungal ($206.7 million) invasions. Reported damage costs (i.e. excluding management costs) were higher in terrestrial ($4.8 billion) than aquatic or semi-aquatic environments ($29.8 million), and primarily impacted agriculture ($4.2 billion). Invaders with earlier introduction years accrued significantly higher total invasion costs. Invasion costs have been increasing rapidly since 1976, and have cost the UK economy $157.1 million (£122.1 million) per annum, on average. Published information on specific economic costs included only 42 of 520 invaders reported in the UK and was generally available only for the most intensively studied taxa, with just four species contributing 90% of species-specific costs. Given that many of the invasive species lacking cost data are actively managed and have well-recognised impacts, this suggests that cost information is incomplete and that totals presented here are vast underestimates owing to knowledge gaps. Financial expenditure on managing invasions is a fraction (37%) of the costs incurred through damage from invaders; greater investments in UK invasive species research and management are, therefore, urgently required.
Full-text available
We contend that the exclusive focus on the English language in scientific research might hinder effective communication between scientists and practitioners or policy makers whose mother tongue is non-English. This barrier in scientific knowledge and data transfer likely leads to significant knowledge gaps and may create biases when providing global patterns in many fields of science. To demonstrate this, we compiled data on the global economic costs of invasive alien species reported in 15 non-English languages. We compared it with equivalent data from English documents (i.e., the InvaCost database, the most up-to-date repository of invasion costs globally). The comparison of both databases (~7500 entries in total) revealed that non-English sources: (i) capture a greater amount of data than English sources alone (2500 vs. 2396 cost entries respectively); (ii) add 249 invasive species and 15 countries to those reported by English literature, and (iii) increase the global cost estimate of invasions by 16.6% (i.e., US$ 214 billion added to 1.288 trillion estimated from the English database). Additionally, 2712 cost entries — not directly comparable to the English database — were directly obtained from practitioners, revealing the value of communication between scientists and practitioners. Moreover, we demonstrated how gaps caused by overlooking non-English data resulted in significant biases in the distribution of costs across space, taxonomic groups, types of cost, and impacted sectors. Specifically, costs from Europe, at the local scale, and particularly pertaining to management, were largely under-represented in the English database. Thus, combining scientific data from English and non-English sources proves fundamental and enhances data completeness. Considering non-English sources helps alleviate biases in understanding invasion costs at a global scale. Finally, it also holds strong potential for improving management performance, coordination among experts (scientists and practitioners), and collaborative actions across countries. Note: non-English versions of the abstract and figures are provided in Appendix S5 in 12 languages.
Full-text available
Aim Large-scale datasets are becoming increasingly available for macroecological research from different disciplines. However, learning their specific extraction and analytical requirements can become prohibitively time-consuming for researchers. We argue that this issue can be tackled with the provision of methodological frameworks published in open-source software. We illustrate this solution with the invacost R package, an open-source software designed to query and analyse the global database on reported economic costs of invasive alien species, InvaCost . Innovations First, the invacost package provides updates of this dynamic database directly in the analytical environment R. Second, it helps understand the nature of economic cost data for invasive species, their harmonisation process, and the inherent biases associated with such data. Third, it readily provides complementary methods to query and analyse the costs of invasive species at the global scale, all the while accounting for econometric statistical issues. Main conclusions This tool will be useful for scientists working on invasive alien species, by (i) facilitating access and use to this multi-disciplinary data resource and (ii) providing a standard procedure which will facilitate reproducibility and comparability of studies, one of the major critics of this topic until now. We discuss how the development of this R package was designed as an enforcement of general recommendations for transparency, reproducibility and comparability of science in the era of big data in ecology.
Full-text available
Biological invasions can cause substantial economic losses and expenses for management, as well as harm biodiversity, ecosystem services and human well-being. A comprehensive assessment of the economic costs of invasions is a challenging but essential prerequisite for efficient and sustainable management of invasive alien species. Indeed, these costs were shown to be inherently heterogeneous and complex to determine, and substantial knowledge gaps prevent a full understanding of their nature and distribution. Hence, the development of a still-missing global, standard framework for assessing and deciphering invasion costs is essential to identify effective management approaches and optimise legislation. The recent advent of the InvaCost database – the first comprehensive and harmonised compilation of the economic costs associated with biological invasions worldwide – offers unique opportunities to investigate these complex and diverse costs at different scales. Insights provided by such a dataset are likely to be greatest when a diverse range of experience and expertise are combined. For this purpose, an international and multidisciplinary workshop was held from 12 th to 15 th November 2019 near Paris (France) to launch several project papers based on the data available in InvaCost. Here, we highlight how the innovative research arising from this workshop offers a major step forward in invasion science. We collectively identified five core research opportunities that InvaCost can help to address: (i) decipher how existing costs of invasions are actually distributed in human society; (ii) bridge taxonomic and geographic gaps identified in the costs currently estimated; (iii) harmonise terminology and reporting of costs through a consensual and interdisciplinary framework; (iv) develop innovative methodological approaches to deal with cost estimations and assessments; and (v) provide cost-based information and tools for applied management of invasions. Moreover, we attribute part of the success of the workshop to its consideration of diversity, equity and societal engagement, which increased research efficiency, creativity and productivity. This workshop provides a strong foundation for substantially advancing our knowledge of invasion impacts, fosters the establishment of a dynamic collaborative network on the topic of invasion economics, and highlights new key features for future scientific meetings.