International audienceProcambarus clarkii is currently recorded from 16 European territories. On top of being a vector of crayfish plague, which is responsible for large-scale disappearance of native crayfish species, it causes severe impacts on diverse aquatic ecosystems, due to its rapid life cycle, dispersal capacities, burrowing activities and high population densities. The species has even been recently discovered in caves. This invasive crayfish is a polytrophic keystone species that can exert multiple pressures on ecosystems. Most studies deal with the decline of macrophytes and predation on several species (amphibians, molluscs, and macroinvertebrates), highlighting how this biodiversity loss leads to unbalanced food chains. At a management level, the species is considered as (a) a devastating digger of the water drainage systems in southern and central Europe, (b) an agricultural pest in Mediterranean territories, consuming, for example, young rice plants, and (c) a threat to the restoration of water bodies in north-western Europe. Indeed, among the high-risk species, P. clarkii consistently attained the highest risk rating. Its negative impacts on ecosystem services were evaluated. These may include the loss of provisioning services such as reductions in valued edible native species of regulatory and supporting services, inducing wide changes in ecological communities and increased costs to agriculture and water management. Finally, cultural services may be lost. The species fulfils the criteria of the Article 4(3) of Regulation (EU) No 1143/2014 of the European Parliament (species widely spread in Europe and impossible to eradicate in a cost-effective manner) and has been included in the “Union List”. Particularly, awareness of the ornamental trade through the internet must be reinforced within the European Community and import and trade regulations should be imposed to reduce the availability of this high-risk species

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We reviewed information on nonnative freshwater fauna in Portugal.• Fish and mollusks are the taxonomic groups with more established species. • Most species are native from other regions of Europe and North America. • The Portuguese and EU legislation showed large discrepancies in its invasive species. • We identified invaders for which legislation and actions are needed.

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The zebra mussel, Dreissena polymorpha (Pallas 1771), is an invasive freshwater species with major negative impacts, promoting changes in ecosystem structure and function and also contributing to economic losses. Navigation has been considered the primary vector of dispersion and little importance has been given to alternative natural (waterbirds) and other human vectors. Using an experimental approach under field conditions, we evaluated and compared zebra mussel dispersal potential by fishing gear (waders and keepnets) versus mallard ducks (Anas platyrhynchos), by examining the adherence and survival rate of zebra mussel larvae on each vector. In addition, we evaluated the survival of zebra mussel larvae under desiccating conditions (i.e., a set of controlled temperatures and relative humidities). Larvae adhered to all types of vectors and survived desiccation under both laboratory and field conditions and thus appear able to be dispersed long distances overland by both ducks and fishing gear. Specifically, on a per-event basis, fishing gear has a higher potential to spread zebra mussel larvae than ducks. Survival was three times higher on human vectors and the number of larvae attached to human vectors was over double of that on the ducks. However, our findings demonstrate that natural vectors, like ducks, can contribute to the transport of zebra mussel larvae at a local scale. Nevertheless, since vectors related to human activity presented a higher potential for transport, it is imperative to continue campaigns to raise the awareness of anglers and boaters as well as continue the implementation of legislation to reduce the risk of zebra mussel dispersal.

Fisheries Management and EcologyEffective management of invasive fishes depends on the availability of updated information 5 about their distribution and spatial dispersion. Forensic analysis was performed using online and 6 published data on the European catfish, Silurus glanis Linnaeus, 1758, a recent invader in the 7Tagus basin (Iberian Peninsula). Eighty records were obtained mainly from anglers' fora and 8 blogs and more recently from www.youtube.com. Since the first record in 1998, S. glanis 9 expanded its geographic range by ≈ 700 km of river network, occurring mainly in reservoirs and 10 in high order sections. Human-mediated and natural dispersal events were identified, with the 11 former occurring during the first years of invasion and involving movements of > 50 km. 12 Downstream dispersal directionality was predominant. This study demonstrates that the 13 analysis of online data from anglers can provide useful information on the distribution and 14 dispersal patterns of this non-native fish, potentially applicable as a preliminary, exploratory 15 assessment tool for other non-native fishes. 16 17

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Key-words: Pacifastacus leniusculus, Procambarus clarkii, desiccation survival, invasive species, dispersalThe signal crayfish, P. leniusculus and the red swamp crayfish, P. clarkii are two invasive crayfish species with widely world distribution, being both present at Iberian Peninsula. In this work we study the desiccation survival capacities of both species at 24 • C. Our results showed that both species are capable of surviving exposure to air for long periods of time, with an LT 90 of 17.6 and 21.5 h, respectively, for red swamp crayfish and signal crayfish. Our findings are in accordance with the great overland dispersal capacities attributed to these crayfish species. RÉSUMÉ Capacités de survie à la dessiccation des deux espèces d'écrevisses invasives Mots-clés :Pacifastacus leniusculus, Procambarus clarkii, survie à la dessiccation, espèces envahissantes, dispersion L'écrevisse signal, Pacifastacus leniusculus et l'écrevisse rouge des marais, Procambarus clarkii sont deux espèces d'écrevisses exotiques avec une distribution mondiale, toutes deux présentes dans la péninsule ibérique. Dans ce travail, nous étudions la capacité de survie à la dessiccation de P. clarkii à 24 • C et 30 % d'humidité relative et de P. leniusculus également à 24 • C, mais à une humidité relative de 50 %. Nos résultats ont montré que les deux espèces sont capables de survivre à l'exposition à l'air pendant de longues périodes de temps, avec une LT 90 de 17,6 et 21,5 h pour l'écrevisse rouge des marais et l'écrevisse signal, respectivement. Nos résultats sont en accord avec les grandes capacités de dispersion par voie terrestre attribuées à ces espèces d'écrevisse.Crayfish are one of the most commonly introduced freshwater organisms and are responsible for declines and extinctions of native species throughout the world (Guan and Wiles, 1997;Lodge et al., 1998Lodge et al., , 2000Nyström et al., 2001, Westman et al., 2002. The signal crayfish Pacifastacus leniusculus (Dana, 1852) and the red swamp crayfish, Procambarus clarkii (Girard, 1852) are two North America native crayfish species with worldwide distribution due to their economic importance, but also due to their high dispersal abilities, fast growing populations and wide niches (Hobbs et al., 1989). Severe negative impacts on invaded areas are attributed to these two crayfish species, such as competition with native species (Nyström, 1999), dissemination of the crayfish plague (Diéguez-Uribeondo et al., 1997), habitat and ecosystem changes (Geiger et al., 2005), negative effects on amphibian populations (Nyström, 1999; Cruz et al., 2008) and losses on economic activities such as rice production (Anastácio et al., 2005). In the Iberian Peninsula these two crayfish were first introduced into Spain nearly at the same time, P. clarkii in 1973 and P. leniusculus in 1974 respectively, for aquaculture purposes (Diéguez-Uribeondo et al., 1997;Alonso et al., 2000). In Portugal, the fist records of these species were in 1979 for P. clarkii in the Caia river (Ramos and Perei...