Non-indigenous Species in European Waters

Invasive alien species (IAS) are one of the major threats to global biodiversity and impose enormous costs to all kind of human ventures, such as agriculture, forestry, fisheries and tourism. As the risks of IAS to ecosystems are becoming more and more evident and broadly acknowledged, the rate of IAS introductions, due to a massive increase in volume and pace of global trade and travel, is becoming overwhelming and difficult to manage. While the world grows smaller with globalization, global biodiversity shrinks, and the uniqueness of localities and islands is lost forever owing to the harmonization processes. Though knowledge on IAS is rapidly growing, large and fundamental gaps still exist.

This excellent book* gives the first comprehensive overview of IAS in aquatic systems in Europe. The editors have notched up a considerable achievement in bringing together all the significant workers on aquatic IAS as authors. As they state in their preface, more than 100 scientists have synthesized the available information on aquatic bioinvasions. The book gives excellent broad coverage. Geographically, it covers the whole of Europe and it also deals with all aquatic environments, from freshwater systems, to brackish areas and marine water bodies. Generally, most chapters are very well written and represent the current state of knowledge on the topics. The key objective of the editors, to summarize the present status and impacts caused by non-indigenous aquatic species, is completely realised, indicating thereby also the gaps in current knowledge.

After two introductory chapters on bioinvasions in European waters, the question of which are the non-indigenous aquatic species is addressed in a series of chapters on the different taxonomic groups. These span all types of organisms associated with the aquatic environment, from protists (an only marginally known component of ballast water), to algae and vascular plants, to one of the worst invaders - the comb jelly Mnemiopsis leidyi , to polychaetes, to crustaceans such as crayfish, to molluscs - e.g. the wood boring cryptogenic shipworm, to alien freshwater fish, and birds and mammals. This full-breadth coverage of all major taxonomic groups indicates the diversity of IAS. The subsequent chapters identify the various vectors for bioinvasions. This diversity of taxonomic groups and pathways renders prevention and management of IAS complicated, since such efforts may need to target many or all of them. All major pathways for aquatic IAS are listed and some are discussed in more detail, especially ballast water and ballast tank sediments, which are responsible for mass introductions, and also aquaculture as a vector for farmed organisms as well as for hitchhiking species. Next, 16 regional overviews of biological invasions in European waters illustrate the geographical extent and the ecological and economic problems caused. That only three papers are presented under the heading of `impacts' is somewhat misleading in the sense that known impacts are mentioned in other chapters, too. However, it also uncovers a lack of knowledge of environmental impacts owing to difficulties in demonstrating direct and (particularly) indirect subtle effects on native species in ecosystems. The next two papers discuss the need for improved risk assessment and describe a risk-based methodology to assess aquatic IAS in ballast water. Under the `treatment measures' heading, current knowledge on options for ballast water treatment is summarized. Finally, the editors give advice on where to look for more information, describing databases on aquatic alien species not only for Europe but for the rest of the world too. The book is completed with an extensive reference list. Unfortunately, there is no index to provide swift guidance for readers interested in particular species. The structure of the book as papers also does not facilitate cross-referencing.

Written primarily for an audience with aquatic interests, this book is recommended to all people involved with IAS, because many problems described are similar in terrestrial systems. Furthermore the marine and freshwater examples broaden the mind and give a more complete picture of the topic. It is a scientific book, thus the readers will primarily be scientists and students. While the title of the book indicates the European focus, IAS scientists and managers from other continents will also find a wealth of information. The chapter about `...control techniques for ballast water' serves as an example; ballast water is a global challenge, three of the seven authors are Australian, and the evaluation and discussion of promising techniques is universal. Another example are the chapters devoted to the zebra mussel, which is regarded as one of the worst invaders in North America and indeed the chapter of its impacts is written by three Americans. This gives the book a more global perspective, but also highlights the lack of knowledge in Europe. The editors asked non-European authors to fill some essential gaps in European research, in particular on impacts, risk assessment and management of IAS. In conclusion, I hope that the book will find a wide readership within the community interested in IAS. The book is also a stimulus to understand and manage IAS instead of being disheartened by the number of invasions.

*Leppäkoski, E; Gollasch, S.; Olenin, S. ( eds ) (2002) Invasive aquatic species of Europe. Distribution, impacts and management. Dordrecht/Boston/London; Kluwer, 583 pp. Price i145/UK£93/US$139.
ISBN 1 4020 0837 6

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Economic and Environmental Costs of Alien Species

The rising tide of concern about alien species is supported by a limited number of estimates for national or global economic impact of alien species. Two frequently quoted figures are one estimate that economic damage associated with non-indigenous species and their control in the USA amounts to US$137 billion ($1.37 ∞ 1011) a year1, and another combined estimate of US$336 billion ($3.36 ∞ 1011) for Australia, Brazil, the British Isles, India, New Zealand, South Africa, and USA2. This book* provides the background to these estimates.

The book consists of an introduction and 17 chapters, three of which have been previously published^1,2,3. The chapters cover Australia (three chapters on plants, vertebrates and invertebrates), Brazil (one chapter on pathogens), the British Isles (three chapters on plants, vertebrates [Great Britain only] and arthropods and plant pathogens), India (one chapter on plant pathogens), New Zealand (three chapters on weeds, vertebrates and insects), South Africa (two chapters on plants, including³ and invertebrates), USA (one chapter on all groups¹), and a global perspective (plants, animals and microbes² and human diseases).

Reviewing the list of chapters, some inconsistencies are obvious: not all groups are covered for all areas; invertebrates, arthropods or insects may be covered; diseases are inconsistently covered; the British Isles or Great Britain are covered (for anyone who is not British or Irish, it may be worth pointing out that the British Isles comprise two main islands, Ireland and Great Britain, and two political entities, Ireland and the United Kingdom of Great Britain and Northern Ireland - I wouldn't labour this point except that the British Isles are sometimes included as a nation in this book). These inconsistencies should not detract from a valiant effort at compiling the available information on economic and environmental impact.

The contributors to the book mostly try to address both environmental and economic costs of alien species. Inevitably, perhaps, the former tends to be descriptive, sometimes anecdotal. There are many useful referenced summaries from the six areas to describe research results on environmental and economic impact of aliens. Coverage of economic aspects of damage and control is more comprehensive. On the converse side, the beneficial results of introduced alien species, such as crops and livestock, although raised, are beyond the scope of the book. However the benefits of biological control are discussed for Australia, South Africa and New Zealand.

The authors acknowledge that often the data can only be considered estimates, and sometimes very rough estimates in the face of conflicting numbers and approaches. For example, a 1993 Office of Technology Assessment estimated the cost of zebra mussel in the USA at US$300,000 per annum, while this book uses a 1997 estimate of $5 billion per annum. Again, for the City of Swansea to control Japanese knotweed is estimated at UK£9.5 million, but they actually spent £140,000 over 6 years; in this case this book goes with the actual expenditure to estimate the costs associated with this weed. Doubtless, we could all find details to question and pick over, but the cumulative totals in this numbers game are undeniable.

Based on per capita costs of alien species in these six areas, extrapolated globally, this book concludes that the economic cost of alien species is 5% of the global economy (US$1.4 trillion, i.e. $1.4 ∞ 1012). This estimate and the estimates cited at the beginning of this review are likely to be heavily used in the future; this book provides the justification for these numbers. It also provides a fully referenced snapshot to a large proportion of the world literature on environmental and economic impact of alien species. Unfortunately, I found the index unreliable several times; hopefully I was just unlucky with these examples, otherwise locating or relocating information may not be as straightforward as one would like. As a source book on impact of alien species this is a valuable reference book, which those dealing with alien species will want to have available.

¹Pimentel, D.; Lach, L.; Zuniga, R.; Morrison, D. (2000) Environmental and economic costs associated with non-indigenous species in the United States. BioScience 50 , 53-65.

²Pimentel D.; McNair, S.; Janecka, J.; Wightman, J.; Simmonds, C.; O'Connell, C.; Wong, E.; Russel, L.; Zern, J.; Aquino, T.; Tsomondo, T. (2001) Economic and environmental threats of alien plant, animal, and microbe invasions. Agriculture, Ecosystems and Environment 84, 1-20.

³van Wilgen, B.W.; Richardson, D.M.; Le Maitre, D.C.; Marais, C.; Magadlela, D. (2001) The economic consequences of alien plant invasions: examples of impacts and approaches to sustainable management in South Africa. Environment, Development and Sustainability 3 , 145-168.

*Pimentel, D. (ed) (2002) Biological invasions: economic and environmental costs of alien plant, animal, and microbe species. Boca Raton/London/New York/Washington DC; CRC Press, 369 pp. Price UK£91/US$129.95. ISBN 0 8493 0636 4

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