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.

BioInvasions Global Change Macroecology Group Department of Botany and Biodiversity Research University Vienna Rennweg 14 1030 Vienna Austria

Biologie des Organismes et Ecosystèmes Aquatiques Muséum national d'Histoire naturelle CNRS IRD Sorbonne Université Université Caen Normandie Université des Antilles 43 rue Cuvier CP 26 75005 Paris France

Center for Applied Mathematics and Bioinformatics Department of Mathematics and Natural Sciences Gulf University for Science and Technology P O Box 7207 Hawally 32093 Kuwait

Centro de Estudos Geográficos Instituto de Geografia 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

Department of Integrative Biology University of South Florida Tampa FL 33620 United States

Department of Zoology and Entomology Rhodes University Makhanda 6140 South Africa; South African Institute for Aquatic Biodiversity Makhanda 6140 South Africa

GEOMAR Helmholtz Zentrum für Ozeanforschung Kiel 24105 Kiel Germany

GEOMAR Helmholtz Zentrum für Ozeanforschung Kiel 24105 Kiel Germany; South African Institute for Aquatic Biodiversity Makhanda 6140 South Africa

ISEM UMR226 Université de Montpellier CNRS IRD EPHE 34090 Montpellier France

Modelling Evidence and Policy Research Group School of Natural and Environmental Sciences Newcastle University Newcastle upon Tyne NE1 7RU UK

School of Biology and Environmental Sciences University of Mpumalanga Nelspruit 1200 South Africa; South African Institute for Aquatic Biodiversity Makhanda 6140 South Africa

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 2 389 25 Vodňany Czech Republic

Tour du Valat Research Institute for the Conservation of Mediterranean Wetlands 13200 Arles France

Univ Rennes CNRS ECOBIO [ ] UMR 6553 F 35000 Rennes France; Institut Universitaire de France 1 Rue Descartes 75231 Paris cedex 05 France

Université Paris Saclay CNRS AgroParisTech Ecologie Systématique Evolution 91405 Orsay 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 and Development Research Group Tietotie 1E FI 00076 Aalto Finland

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

References provided by Crossref.org

Using species ranges and macroeconomic data to fill the gap in costs of biological invasions

Recent advances in availability and synthesis of the economic costs of biological invasions

Unveiling the hidden economic toll of biological invasions in the European Union

Building a synthesis of economic costs of biological invasions in New Zealand

Global economic costs of herpetofauna invasions

Survival, Growth, and Reproduction: Comparison of Marbled Crayfish with Four Prominent Crayfish Invaders