Riccardo Scalera

No saturation in the accumulation of alien species worldwide

Although research on human-mediated exchanges of species has substantially intensified during the last centuries, we know surprisingly little about temporal dynamics of alien species accumulations across regions and taxa. Using a novel database of 45,813 first records of 16,926 established alien species, we show that the annual rate of first records worldwide has increased during the last 200 years, with 37% of all first records reported most recently (1970–2014). Inter-continental and inter-taxonomic variation can be largely attributed to the diaspora of European settlers in the nineteenth century and to the acceleration in trade in the twentieth century. For all taxonomic groups, the increase in numbers of alien species does not show any sign of saturation and most taxa even show increases in the rate of first records over time. This highlights that past efforts to mitigate invasions have not been effective enough to keep up with increasing globalization.

Animal xenodiversity in Italian inland waters: distribution, modes of arrival, and pathways

The paper provides a list of the non-indigenous animal species occurring today in Italian inland waters. Xenodiversity was found to amount to 112 species (64 invertebrates and 48 vertebrates), which contribute for about 2% to the inland-water fauna in Italy. Northern and central regions are most affected, and Asia, North America, and the rest of Europe are the main donor continents. The large majority of non-indigenous species entered Italy as a direct or indirect effect of human intervention. A difference between invertebrates and vertebrates was found for their mode of arrival (unintentional for invertebrates and intentional for vertebrates). Accidental transport, in association with both fish (for aquaculture or stock enhancement) and crops, has been the main vector of invertebrate introductions, whereas vertebrates were mostly released for stocking purposes. Overall stock enhancement (47.92%) and culture (37.5%) prevailed over the other pathways. Seventeen and 7 species of our list are included among the 100 worst invasive species of Europe (DAISIE) and of the world (IUCN), respectively. For some (but not all) non-indigenous species recorded in Italy the multilevel impact exerted on the recipient communities and ecosystems is known, even if rarely quantified, but knowledge on their chronic impact is still missing. Additional research is needed to provide criteria for prioritizing intervention against well established invaders and identify which new potential invader should be targeted as “unwanted”.

Alien Mammals of Europe

Mammals are large, charismatic animals that have a mineralised skeleton that may form long lasting fossils. For these reasons, the level of knowledge on this class, together with other vertebrates, is much higher than for any other animal group. Therefore, the available information on introduction patterns, trends of invasions, and detrimental impacts caused to the environment and to human well-being are more detailed than for other groups covered in the DAISIE project. History of mammal invasions is very long, as anthropogenic introductions of mammals started at least since the beginning of the Neolithic period. Ancient introductions involved wild species commensal of humans (i.e., black rat Rattus rattus and house mouse Mus musculus), anthropophilous (i.e., lesser white-toothed shrew Crocidura suaveolens and wood mouse Apodemus sylvaticus) and domestic species (i.e. species domesticated in the Middle East and gone feral, like the Corsican mouflon Ovis aries). Data on alien mammals have been collected from available global reviews (Long 2003; Mitchell-Jones et al. 1999; Lever 1985), national inventories (Austria: Englisch 2002; Denmark: Baagoe and Jensen 2007; France: Pascal et al. 2006; Germany: Geiter et al. 2002; Ireland: Stokes et al. 2006; Italy: Andreotti et al. 2001; Scalera 2001; Liechtenstein: Broggi 2006; Scandinavian countries: Weidema 2000; Spain: Nogales et al. 2006; Palomo and Gisbert 2002; Switzerland: Wittenberg 2006; the UK: Battersby and Tracking Mammals Partnership 2005; Weijden et al. 2005). Databases available on the internet were also used as a source of information (i.e. for Belgium, the Nordic countries, etc.). Other data have been collected through inputs of the experts of the DAISIE consortium, but also with the valuable support of many experts of the IUCN Invasive Species Specialist Group and of the Group of Experts on Invasive Alien Species of the Council of Europe. Independent experts have verified each record, which included information on taxonomy, native range, vector and pathway of introduction, date of introduction, status of the species, basic information on population size, distribution and impacts. Based on the DAISIE database, in the present chapter we present an overview of the main patterns of mammal invasions in Europe, and analyse the main environmental, social and economic correlates to the arrival and successful establishment.

One Hundred of the Most Invasive Alien Species in Europe

One of the primary tools for raising awareness on biological invasions has been the publication of species accounts of the most prominent alien invaders. Until now such compilations have been available only for particular taxa, biomes and/or regions (Cronk and Fuller 2001; Weber 2003; Weidema 2000). In Europe, species accounts for selected invasive species have been published for a few countries or regions: the Czech Republic (Mlikovský and Stýblo 2006), France (Pascal et al. 2006), Italy (Andreotti et al. 2001; Scalera 2001), Spain (Capdevila-Arguelles and Zilletti 2006); the Mediterranean Sea (CIESM 2007), and the North European and Baltic region (Gollasch et al. 1999; NOBANIS 2007). These accounts highlight invasive alien species which cause significant harm to biological diversity, socioeconomic values and human health in these regions. The main purpose of these accounts is to provide guidance to environmental managers and raise public awareness of the biological, ecological and socio-economic impacts of the most harmful invaders, together with a description of the main management options to prevent their spread and reduce their impacts. The importance of the role of such tools has been clearly shown by the IUCN’s 100 of the World’s Worst Invasive Species list (Love et al. 2000) which has been very influential in raising awareness and supporting the development of policy conservation instruments relevant to biological invasions (Shine et al. 2000). The European Environmental Agency has produced, within the SEBI 2010 project, a list of the worst invasive alien species threatening biological diversity in Europe (EEA 2007). This list contributes to the general indicator of changes in biological diversity caused by invasive alien species. The SEBI 2010 list is primarily a means to communicate the issue of invasive species to policymakers, stakeholders and the general public. The selection of the 168 species on the list was carried out in an open consultative process with an expert group, the scientific community and national environmental authorities. The main criterion used for selection was that the species have a serious impact on biological diversity at the regional level. Serious impact implies that the species has severe effects on ecosystem structure and function, it can replace native species throughout a significant proportion of its range, it can hybridise with native species or threaten biodiversity. In addition, the species can have negative consequences for human activities, health and/or economic interests.

A prioritised list of invasive alien species to assist the effective implementation of EU legislation

Effective prevention and control of invasive species generally relies on a comprehensive, coherent and representative list of species that enables resources to be used optimally. European Union (EU) Regulation 1143/2014 on invasive alien species (IAS) aims to control or eradicate priority species, and to manage pathways to prevent the introduction and establishment of new IAS; it applies to species considered of Union concern and subject to formal risk assessment. So far, 49 species have been listed but the criteria for selecting species for risk assessment have not been disclosed and were probably unsystematic. We developed a simple method to systematically rank IAS according to their maximum potential threat to biodiversity in the EU. We identified 1,323 species as potential candidates for listing, and evaluated them against their invasion stages and reported impacts, using information from databases and scientific literature. 900 species fitted the criteria for listing according to IAS Regulation. We prioritised 207 species for urgent risk assessment, 59 by 2018 and 148 by 2020, based on their potential to permanently damage native species or ecosystems; another 336 species were identified for a second phase (by 2025), to prevent or reverse their profound impacts on biodiversity; and a further 357 species for assessment by 2030. Policy implications. We propose a systematic, proactive approach to selecting and prioritising IAS for risk assessment to assist European Union policy implementation. We assess an unprecedented number of species with potential to harm EU biodiversity using a simple methodology and recommend which species should be considered for risk assessment in a ranked order of priority along the timeline 2018–2030, based on their maximum reported impact and their invasion history in Europe.

Developing a framework of minimum standards for the risk assessment of alien species

1. Biological invasions are a threat to biodiversity, society and the economy. There is an urgent need to provide evidence-based assessments of the risks posed by inva-sive alien species (IAS) to prioritize action. Risk assessments underpin IAS policies in many ways: informing legislation; providing justification of restrictions in trade or consumer activities; prioritizing surveillance and rapid response. There are benefits to ensuring consistency in content of IAS risk assessments globally, and this can be achieved by providing a framework of minimum standards as a checklist for quality assurance. 2. From a review of existing risk assessment protocols, and with reference to the r equirements of the EU Regulation on IAS (1143/2014) and international agreements including the World Trade Organisation, Convention on Biological Diversity and International Plant Protection Convention, coupled with consensus methods, we identified and agreed upon 14 minimum standards (attributes) a risk-assessment scheme should include. 3. The agreed minimum standards were as follows: (1) basic species description; (2) likelihood of invasion; (3) distribution, spread and impacts; (4) assessment of intro-duction pathways; (5) assessment of impacts on biodiversity and ecosystems; (6) Assessment of impact on ecosystem services; (7) assessment of socio-economic impacts; (8) consideration of status (threatened or protected) of species or habitat under threat; (9) assessment of effects of future climate change; (10) completion possible even when there is a lack of information; (11) documents information sources; (12) provides a summary in a consistent and interpretable form; (13) includes uncertainty; (14) includes quality assurance. In deriving these minimum standards, gaps in knowledge required for completing risk assessments and the scope of exist-ing risk assessment protocols were revealed, most notably in relation to assessing benefits, socio-economic impacts and impacts on ecosystem services but also inclu-sion of consideration of climate change. 4. Policy implications. We provide a checklist of components that should be within in-vasive alien species risk assessments and recommendations to develop risk assess-ments to meet these proposed minimum standards. Although inspired by implementation of the European Union Regulation on invasive alien species, and as such developed specifically within a European context, the derived framework and minimum standards could be applied globally.

Seven recommendations to make your invasive alien species data more useful

Science-based strategies to tackle biological invasions depend on recent, accurate, well-documented, standardised and openly accessible information on alien species. Currently and historically, biodiversity data are scattered in numerous disconnected data silos that lack interoperability. The situation is no different for alien species data, and this obstructs efficient retrieval, combination, and use of these kinds of information for research and policy-making. Standardization and interoperability are particularly important as many alien species related research and policy activities require pooling data. We describe seven ways that data on alien species can be made more accessible and useful: 1) Create data management plans; 2) Increase interoperability of information sources; 3) Document data through metadata; 4) Format data using existing standards; 5) Adopt controlled vocabularies; 6) Increase data availability; and 7) Ensure long-term data preservation. We identify four properties specific and integral to alien species data (species status, introduction pathway, degree of establishment, and impact mechanism) that are either missing from existing data standards or lack a recommended controlled vocabulary. Improved access to accurate, real-time and historical data will repay the long-term investment in data management infrastructure, by providing more accurate, timely and realistic analyses. If we improve core biodiversity data standards by developing their relevance to alien species, it will allow the automation of common activities regarding data processing in support of environmental policy. Furthermore, we call for considerable effort to maintain, update, standardise, archive, and aggregate datasets, to ensure proper valorisation of alien species data and information before they become obsolete or lost.