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As the number of introduced species keeps increasing unabatedly, identifying and prioritising current and potential Invasive Alien Species (IAS) has become essential to manage them. Horizon Scanning (HS), defined as an exploration of potential threats, is considered a fundamental component of IAS management. By combining scientific knowledge on taxa with expert opinion, we identified the most relevant aquatic IAS in the Iberian Peninsula, i.e., those with the greatest geographic extent (or probability of introduction), severe ecological, economic and human health impacts, greatest difficulty and acceptability of management. We highlighted the 126 most relevant IAS already present in Iberian inland waters (i.e., Concern list) and 89 with a high probability of being introduced in the near future (i.e., Alert list), of which 24 and 10 IAS, respectively, were considered as a management priority after receiving the highest scores in the expert assessment (i.e., top-ranked IAS). In both lists, aquatic IAS belonging to the four thematic groups (plants, freshwater invertebrates, estuarine invertebrates, and vertebrates) were identified as having been introduced through various pathways from different regions of the world and classified according to their main functional feeding groups. Also, the latest update of the list of IAS of Union concern pursuant to Regulation (EU) No 1143/2014 includes only 12 top-ranked IAS identified for the Iberian Peninsula, while the national lists incorporate the vast majority of them. This fact underlines the great importance of taxa prioritisation exercises at biogeographical scales as a step prior to risk analyses and their inclusion in national lists. This HS provides a robust assessment and a cost-effective strategy for decision-makers and stakeholders to prioritise the use of limited resources for IAS prevention and management. Although applied at a transnational level in a European biodiversity hotspot, this approach is designed for potential application at any geographical or administrative scale, including the continental one., This research was supported by the LIFE INVASAQUA project (Aquatic In- vasive Alien Species of Freshwater and Estuarine Systems: Awareness and Prevention in the Iberian Peninsula) (LIFE17 GIE/ES/000515) funded by the EU LIFE Program. The Fundación Biodiversidad (Government of Spain) and the Government of Navarre financially support specific actions into the LIFE INVASAQUA. F.R. is supported by Foundation for Science and Technology through an individual contract (CEEC/0482/2020). J.E. has a Ph.D. scholarship (SFRH/BD/140556/2018) funded by FCT, Portugal. F.B. is supported by Foundation for Science and Technology through an individual contract (CEEC/01896/2021).

The invasive red swamp crayfish Procambarus clarkii is present in most of the Portuguese rivers with well-known economic and environmental impacts, being also an important reservoir for many fungal and bacterial pathogens that can affect native aquatic fauna. Here the bacterial microbiota of the gut and carapace of the red swamp crayfish from three distinct localities in Portugal was characterized, using a metataxonomic approach. We tested whether biological measurements (sex, cephalotorax lenght, body condition and stress through glucose measurements) and sampling locality can be used as predictors of alpha and beta bacterial diversity. Results showed that the carapace microbiota are more responsive to differing environmental conditions than the gut microbiota, which are likely more affected by host factors, such as sex. Additionally, we have also found several potential pathogens in the microbiota of the analyzed crayfish. Our data provide a relevant baseline of the red swamp crayfish microbiota but highlight the need for further research, namely to fully characterize its role as a vector for bacterial diseases in freshwater ecosystems.

Several freshwater crayfish species, including

The freshwater pearl mussel Margaritifera margaritifera has been suffering major population declines in Europe. This endangered species is a host specialist and exclusively requires salmonid species (Salmo trutta and Salmo salar) to complete its life cycle. In theory, obligatory biotic interactions should deserve special conservation attention, because the loss or massive decline of fish hosts may elicit the extirpation of their affiliated species. While many threats disturbing M. margaritifera are similarly affecting salmonids, climate change is particularly alarming, with the potential to significantly change the fish-mussel dynamics. To evaluate the importance of including the occurrence of fish hosts for predicting the distribution of M. margaritifera in Europe, three datasets were used to build species distribution models (SDMs) with a maximum entropy (MaxEnt) approach: (1) environmental variables (ENV); (2) probability of fish hosts occurrence (FH); and (3) environmental variables and probability of fish hosts occurrence (ENV + FH). We identified the environmental variables that better explain M. margaritifera distribution and modelled its current and future distribution under a suite of climate change scenarios. Furthermore, projections were used to evaluate the adequacy of current networks of European protected areas in covering the suitable habitats for M. margaritifera. Results showed that incorporating data about fish hosts into M. margaritifera SDMs avoided the overprediction of geographical projections and, to a minor extent, improved model performance (area under the curve: ENV = 0.851; FH = 0.848; ENV + FH = 0.867). The distribution range of M. margaritifera in Europe is expected to contract in all future timeframes and emission scenarios considered. Forecasts point to large contractions particularly in central and southern Europe and lowland regions. The European network of protected areas fails to protect 69% of the current and 66%–67% of the future predicted M. margaritifera distribution. This study clearly illustrates the importance of including mussel–fish hosts interactions for accurately predicting M. margaritifera's distribution. The response of M. margaritifera to environmental variables highlights its vulnerability to the higher temperatures, particularly in southern Europe. While predictions indicate large contractions in M. margaritifera's distribution as a result of future climate change, the current European network of protected areas fails to safeguard M. margaritifera. This work provides strong evidence for proposing the generalised use of biotic information about hosts in addition to purely environmental variables to model the distribution of freshwater mussels, as well as for other species with obligatory biotic interactions. Building SDMs such as those discussed here can inform political decision-making about the likely scenarios for species occurrence in future decades, the requirements needed for an effective conservation strategy, and the regions where conservation should be a priority., This work was supported by the Portuguese Foundation for Science and Technology (FCT) and the European Social Fund through the North Portugal Regional Operational Programme through a doctoral Grant to J.S. (SFRH/ BD/146492/2019), through the project MUSSELFLOW (contract PTDC/BIAEVL/29199/2017), by POSEUR-03-2215- FC-000096 and ICNF funds under project CP01-MARG-QUERCUS/2018 and by the Strategic Funding UIDB/04423/2020 and UIDP/04423/2020. MG was supported by the project UIDB/04292/2020 - MARE. F.B. was hired by LIFE Invasaqua project (LIFE17 GIE/ES/000515). D.V.G. was supported by the project ConBiOmics (NORTE-01-0145-FEDER-030286, contract IA/2018–079). FCT also supported A.F.F. (2020.03872.CEECIND) and M.L.L. (2020.03608.CEECIND) under the Stimulus of Scientific Employment CEEC Individual 2020.

Invasive bivalves continue to spread and negatively impact freshwater ecosystems worldwide. As different metrics for body size and biomass are frequently used within the literature to standardise bivalve-related ecological impacts (e.g. respiration and filtration rates), the lack of broadly applicable conversion equations currently hinders reliable comparison across bivalve populations. To facilitate improved comparative assessment among studies originating from disparate geographical locations, we report body size and biomass conversion equations for six invasive freshwater bivalves (or species complex members) worldwide: Corbicula fluminea, C. largillierti, Dreissena bugensis, D. polymorpha, Limnoperna fortunei and Sinanodonta woodiana, and tested the reliability (i.e. precision and accuracy) of these equations. Body size (length, width and height) and biomass metrics of living-weight (LW), wet-weight (WW), dry-weight (DW), dry shell-weight (SW), shell free dry-weight (SFDW) and ash-free dry-weight (AFDW) were collected from a total of 44 bivalve populations located in Asia, the Americas and Europe. Relationships between body size and individual biomass metrics, as well as proportional weight-to-weight conversion factors, were determined. For most species, although inherent variation existed between sampled populations, body size directional measurements were found to be good predictors of all biomass metrics (e.g. length to LW, WW, SW or DW: R2 = 0.82–0.96), with moderate to high accuracy for mean absolute error (MAE): ±9.14%–24.19%. Similarly, narrow 95% confidence limits and low MAE were observed for most proportional biomass relationships, indicating high reliability for the calculated conversion factors (e.g. LW to AFDW; CI range: 0.7–2.0, MAE: ±0.7%–2.0%). Synthesis and applications. Our derived biomass prediction equations can be used to rapidly estimate the biologically active biomass of the assessed species, based on simpler biomass or body size measurements for a wide range of situations globally. This allows for the calculation of approximate average indicators that, when combined with density data, can be used to estimate biomass per geographical unit-area and contribute to quantification of population-level effects. These general equations will support meta-analyses, and allow for comparative assessment of historic and contemporary data. Overall, these equations will enable conservation managers to better understand and predict ecological impacts of these bivalves. Fil: Coughlan, Neil E.. The Queens University of Belfast; Irlanda. University College Cork; Irlanda Fil: Cunningham, Eoghan M.. The Queens University of Belfast; Irlanda Fil: Cuthbert, Ross N.. The Queens University of Belfast; Irlanda. Geomar-Helmholtz Centre for Ocean Research Kiel; Alemania Fil: Joyce, Patrick W. S.. The Queens University of Belfast; Irlanda Fil: Anastácio, Pedro. Universidade de Évora; Portugal Fil: Banha, Filipe. Universidade de Évora; Portugal Fil: Bonel, Nicolás. Université Montpellier II; Francia. Centre National de la Recherche Scientifique; Francia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina Fil: Bradbeer, Stephanie J.. University of Leeds; Reino Unido Fil: Briski, Elizabeta. Geomar-Helmholtz Centre for Ocean Research Kiel; Alemania Fil: Butitta, Vince L.. University of Wisconsin; Estados Unidos Fil: Cadková, Zuzana. Czech University of Life Sciences; República Checa Fil: Dick, Jaimie T. A.. The Queens University of Belfast; Irlanda Fil: Douda, Karel. Czech University of Life Sciences; República Checa Fil: Eagling, Lawrence E.. The Queens University of Belfast; Irlanda Fil: Ferreira Rodríguez, Noé. Universidad de Vigo; España Fil: Hünicken, Leandro Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Johansson, Mattias L.. University of North Georgia; Estados Unidos Fil: Kregting, Louise. The Queens University of Belfast; Irlanda Fil: Labecka, Anna Maria. Jagiellonian University; Polonia Fil: Li, Deliang. Hunan Agricultural University; China Fil: Liquin, Florencia Fernanda. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto para el Estudio de la Biodiversidad de Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina Fil: Marescaux, Jonathan. University of Namur; Bélgica. e-biom; Bélgica Fil: Morris, Todd J.. Fisheries and Ocean Canada; Canadá Fil: Nowakowska, Patrycja. University of Gdansk; Polonia Fil: Ozgo, Malgorzata. Kazimierz Wielki University; Polonia Fil: Paolucci, Esteban Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina Fil: Peribáñez, Miguel A.. Universidad de Zaragoza; España Fil: Riccardi, Nicoletta. Consiglio Nazionale delle Ricerche; Italia Fil: Smith, Emily R. C.. University College London; Estados Unidos Fil: Sylvester, Francisco. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Instituto para el Estudio de la Biodiversidad de Invertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina

One of the main drivers of biodiversity loss is the introduction of exotic invasive species. In 2011, an abundant population of Crangonyx pseudogracilis, a freshwater amphipod native to North America, was detected in Portugal. This study allowed us to better understand its biology, analysing the population dynamics in a temporary river and a small lake for one year, and to follow its expansion. Our results showed that this species reproduces in the temporary river during most of the year, but in the lake only from March to July. Amphipod density decreases from May to October and increases from November to April. As usual, females were larger than males, but the proportion of females was higher than males at both sampling locations. Finally, we noticed a great increase in C. pseudogracilis distribution area in relation to what was observed in 2014, with a diffusion coefficient of 2495.27 km2/year and a spread rate of 26 km/year. However, no overlap was yet detected between native and exotic amphipod species.

Public engagement is vital to effectively manage Invasive Alien Species (IAS) and biosecurity campaigns directed to stakeholders are decisive to raise awareness regarding IAS regulations and problems. To design and implement adequate communication plans, stakeholders' perceptions and risk behaviors regarding IAS need to be monitored by surveys. IAS do not recognize borders and most countries are not biogeographically isolated. Therefore, international information and consensus are necessary when applying measures at a biogeographic scale. Our bilingual survey was performed at the Iberian Peninsula, targeting the general public, decision-makers and other stakeholders, covering all taxa associated to inland aquatic ecosystems. We found differences in IAS' awareness between countries, and between different stakeholder groups. Results showed that the awareness of socioeconomic and human health impacts is substantially lower when compared with impacts on biodiversity. We found that the perception regarding the predation impacts is consistent across groups and countries, while other perceptions differ. The negative socioeconomic impact on angling due to IAS introductions is widely recognized. However, angling is also the activity most referred as positively impacted by IAS due to fish introductions. Most responders knew what IAS are, providing correct species examples. For all three awareness types (Biodiversity, Socio-economic and Human health) the model regressions showed that the most important predictor was the country of provenance of the respondent, followed by Education level for the socio-economic and biodiversity regressions and the stakeholder group in the Human health regression. We can conclude that in Portugal and Spain the general public and other key target-groups have reduced understanding of some threats posed by IAS. We highlight that raising awareness about IAS impacts on humans, namely on socio-economic aspects and human health, may be more effective and it is certainly needed in education campaigns towards IAS.

Freshwater biodiversity is declining at an accelerated pace. Climate change and associated global warming and changes in precipitation patterns, combined with the expansion of generalist -invasive species are two of the main threats. Niche-based models (NBMs) are becoming inevitable tools in invasive species risk assessment and in conservation decision-making. Lithobates catesbeianus is an invasive species globally known for its adverse ecological impacts on native amphibians and biodiversity. To assess species current and future climatic suitable areas at the global and European scales we used an ensemble forecasting approach. We considered six climatic variables, three timeframes (current, 2050, and 2070), and two CO2 emission scenarios. Temperature seasonality, minimum temperature of the coldest month, maximum temperature of the warmest month, and precipitation in the driest month were the most important variables predicting bullfrog occurrence. Globally currently 3.8% of land area is suitable for bullfrog and an increase of up to 5.2% in 2070 is expected. Increase in suitable areas is expected at higher latitudes, especially in North America and central Europe. Currently, 3.45% of total Natura 2000 area is suitable, and a predicted range gain of up to 355.93% (12.28%) is expected in the highest concentration scenarios predictions. This can indicate that the 64 native amphibian species present in the Natura 2000 network could be at increased risk. The choice of Natura 2000 for a geographic detailed analysis of the possible effects on native amphibians is due to its importance for habitats and wildlife conservation. Identification of its invasion-susceptible areas will allow resource and management practices optimization.

Aquarium pets release is an important vector for invasive species establishment in freshwater ecosystems. Here the perceptions and risk behaviors associated to this vector were evaluated using a survey. Portuguese aquarium hobbyists were interviewed through an on-line survey (Google forms) publicized in 9 web sites connected to this hobby (Facebook pages and internet forums). A Pet Propagule Pressure index (PPP), congregating information regarding pet’s popularity and electivity for discharge, was developed and applied in this study, so that relative comparisons can be made among different pet types (taxa). Additionally, non-metric Multidimensional Scaling (nMDS) was applied to pet owner’s data to identify indicator factors associated with risk behaviors and impacts’ awareness. Results indicated that aquarium pet owners usually only have one pet type, most commonly fish or turtles. Only 8% of the owners admit having discharged pets, being more commonly reported the release of only one pet. This risk behavior is connected mainly to the excessive growth of the pet and consequently lack of space in the aquariums. Pet’s discharge occurs until 100 km of distance from owner’s homes, being very common at distances lower than 1 km. The PPP index developed in this study, indicates the pet types with higher risk of discharge were the turtles and the fishes. Pet owner’s awareness regarding the pet discharges impacts in the environment seems to be lower than other risk groups connected to biological invasions in freshwaters, namely anglers. Pet owners most aware of these impacts were associated to higher education levels and higher experience on this hobby. Our study highlights the needs for more environmental education on particular social groups within aquarium pets’ owners, namely those that have started this activity or have lower education levels, to decrease the biological invasion risks associated to this hobby. Additionally, our findings regarding the patterns and drivers of discharge action itself are useful to model risk invasion, as well as for detection, management and control of these species.

Experimental animal models are a valuable tool to study the neurobiology of emotional behavior and mechanisms underlying human affective disorders. Mounting evidence suggests that various aquatic organisms, including both vertebrate (e.g., zebrafish) and invertebrate (e.g., crayfish) species, may be relevant to study animal emotional response and its deficits. Ideally, model organisms of disease should possess considerable genetic and physiological homology to mammals, display robust behavioral and physiological responses to stress, and should be sensitive to a wide range of drugs known to modulate stress and affective behaviors. Here, we summarize recent findings in the field of zebrafish- and crayfish-based tests of stress, anxiety, aggressiveness and social preference, and discuss further perspectives of using these novel model organisms in translational biological psychiatry. Outlining the remaining questions in this field, we also emphasize the need in further development and a wider use of crayfish and zebrafish models to study the pathogenesis of affective disorders.

We present the most updated list of non-native freshwater fauna established in Portugal, including the Azores and Madeira archipelagos. This list includes 67 species at national level but corresponds to 84 species records, of which 53 are in the mainland, 23 in the Azores and 8 in Madeira archipelagos. We also discuss the progression of the cumulative number of introductions since 1800 and identify the most probable vectors of introduction, main taxonomic groups and their regions of origin. Furthermore, we review the existing knowledge about ecological and economic impacts, invasion risk and potential distribution of invaders, under present and future climatic conditions, and the applied management actions, including the production of legislation. Along the 20th century the number of successful introductions increased at an approximate rate of two new species per decade until the beginning of 1970s. Since then, this rate increased to about 14 new species per decade. These introductions were mainly a result of fisheries, as contaminants or for ornamental purposes. Fish and mollusks are the taxonomic groups with more established species, representing more than half of the total. Most species (>70%) are native from other regions of Europe and North America. Studies about ecological or socioeconomic impacts are more common for fish, crustaceans and mollusks. Impacts for most amphibians, reptiles and mammals are not thoroughly studied. A few studies on the impacts and management actions of health-threatening mosquitoes are also available. The potential distribution in the Portuguese territory was modelled for 26 species. Only a minority of these models provides projections of distributions under scenarios of future climate change. A comparison of the Portuguese and EU legislation shows large discrepancies in the invasive species lists. Using the EU list and a ranking procedure for the national context, we identify freshwater species of high national concern for which actions are urgently needed., This work was supported by the FRISK Project (Ref. PTDC/AAG-MAA/0350/2014) to F. Ribeiro and by the strategic plan of MARE - Marine and Environmental Sciences Centre (UID/MAR/04292/2013) to F. Banha with a short term post-doc grant on the University of Evora and a small project. A. F. Filipe was supported by the FRESHING project funded by FCT and COMPETE (PTDC/AAG-MAA/2261/2014 - POCI-01-0145-FEDER-356 016824). R. Sousa was supported by FRESHCO project (contract: PTDC/AGRFOR/1627/2014) funded by FCT.

Anglers are a recognized vector for invasive fauna, with both intentional and accidental introductions reported worldwide. The purpose of this study was to investigate the Iberian freshwater angler's habits and perceptions related to biological invasions, using an international and bilingual survey in Spain and Portugal. The results showed that anglers from both countries cover great distances to fish, and that they commonly visit several places and fish during consecutive days, representing a major risk for invasions. Yet, anglers' activity patterns throughout the year are not constant: the summer months involve more intense activity and, hence, entail higher risk. In both countries, the preferred fish species were invasive, and their introductions were reported more often than native species, with motivations being country-dependent. The use of live bait was not frequent, but sometimes invasive species were used and the release of unused bait in the water was reported very frequently. Most anglers recognize that introductions have environmental impacts and that anglers have an active role in intentional introductions. However, only a minority is aware of the angler's role in accidental transportation of invasive species. These findings on anglers' behaviour patterns and perceptions may be used to model invasion risks and also improve monitoring and awareness programmes led by government agencies. Copyright © 2016 John Wiley & Sons, Ltd.

Crangonyx pseudogracilis is a North American amphipod recently detected in Portugal and it is the first invasive freshwater amphipod detected in the Iberian Peninsula. The aim of this study was to assess the population structure and its invasion range in this area, but also to assess its pathogen profile and its origin through genetic analyses. Crangonyx pseudogracilis was only found in the lowlands of the Tagus River basin, a restricted area of the three sampled river basins (Tagus, Guadiana and Sado). Only one mitochondrial DNA (mtDNA) gene cytochrome oxidase subunit 1 (COI) haplotype, identical to the one already detected in Europe and in the Lake Charles, USA, was identified. The obtained data show that the studied populations are well-established, have a high female fecundity and a reproduction period extended throughout the year. No parasites were detected in the 236 dissected specimens. The dissimilarity of parasites prevalence to other European invasive populations opens the possibility of a direct introduction from North America but it also does not exclude the possibility of a secondary introduction from another European country.

The Chinese mitten crab (Eriocheir sinensis) is an invasive crustacean with a widespread distribution, sometimes overlapping with the red swamp crayfish (Procambarus clarkii). E. sinensis performs long river migrations, often moving overland to cross obstacles, but the factors affecting its movement are not well known. We studied its movement speed in and out of water, the survival time out of water and also its interaction with the red swamp crayfish during dispersal. At 16°C the LT50 (time to death of 50% of the individuals) was 70 h, with a mean weight loss of 20%, and at 24°C the LT50 was 31 h, with a mean 22% weight loss. In and out of the water, these crabs moved with mean velocities of 0.074 and 0.016 m s−1, respectively. P. clarkii did not affect the dispersion of E. sinensis. This crab was able to disperse under various environmental conditions and its speed was affected by density, temperature, relative humidity, carapace length, and condition of the individuals (Fulton index). Moreover, we found that this species has a great capacity to resist desiccation. These characteristics give them all the requirements to successfully invade and adapt to new areas.

Red swamp crayfish (Procambarus clarkii) and signal crayfish (Pacifastacus leniusculus) are two invasive freshwater species with a worldwide distribution. The objective of this work was to investigate how the two species move and use space in an area of recent coexistence. Simultaneously, we test the use of new tools and indices to describe their movement patterns. To accomplish this we performed a radio-tracking program within a river-type habitat during two different periods (September/October 2010 and June/July 2013). We used spatial analysis tools to map crayfish radio-location data with and without accounting for the curvature of the river. To assess the consistency of the direction of movement and of the distances traveled by crayfish, two indices were developed. To assess the habitat preferences of each species we applied Ivlev's Electivity Index and the Standardized Forage Ratio. Movement of P. clarkii and P. leniusculus differed. The average detected movement was 8.8 m day−1 for P. clarkii and 17.5 m day−1 for P. leniusculus. However, crayfish behavior ranged from almost complete immobility – sometimes during several days – to large movements, in half a day, up to a maximum of 255 m for P. clarkii and 461 m for P. leniusculus. The proportion of upstream or downstream movements was independent of the species and both species displayed no preference for either direction. The indices of consistency of movement showed a large interindividual variation. Species and period (2010 or 2013) affected the mean daily distance traveled, maximum observed distance from location of release and percentage of observations under vegetation cover. The Ivlev's Electivity Index and the Standardized Forage Ratio presented similar results. P. clarkii showed a preference for pool areas with riparian vegetation cover while P. leniusculus preferred riffle and pool areas with riparian vegetation cover. Our work provided new and valuable data for modeling the active dispersal of these two problematic invaders in a context of coexistence.

Fishing activities strongly contribute to biological invasions in freshwaters. The purpose of this study was to investigate the potential risks of live bait capture using dip nets and of crayfish trapping as vectors for invasive freshwater macrofauna dispersal. In the Tagus river basin (Portugal), where both activities are common, we evaluated the probability of capture and the electivity of the local aquatic macrofauna according to the method used. During the compulsory removal of the invasive species captured we also quantified fish desiccation survival capacities. We found, for both vectors, that the species exhibiting the highest probability of capture and the highest electivity were invasive, respectively, Gambusia holbrooki and Crangonyx pseudogracilis with the dip net, Procambarus clarkii and several invasive species with special relevance for Ameiurus melas with the crayfish trapping. Moreover, the desiccation survival capacities, of all invasive fishes analyzed, are compatible with long distance dispersal out of water, with special relevance to G. holbrooki. This study demonstrates that fishing activities contribute to long-distance dispersal of invasive fauna. Therefore, according to our findings, it is important to update the fishing regulation and simultaneously to raise fishermen awareness of this problem.

Pet release is important for the introduction of invasive species but propagule pressure from this pathway is higher in areas with intense human presence. In fact, potential invaders are frequently released into areas with sub-optimal environmental conditions, and are not able to reproduce or establish viable populations. SDMs are mainly focused on determining species environmental suitability and in the case of invasive species modelling these do not integrate the invasion as a process, missing the crucial human contribution. Our model aims to introduce novelty by incorporating variables representing human activities such as pet shop densities or human areas. These are directly related with the studied species invasion pathway. Here we investigate the binomial influence of reproductive occurrences and human-related variables on invasive pet distribution modelling. As our model species, we used the red-eared slider turtle, Trachemys scripta elegans (T.s.e.) , an iconic invasive species with worldwide dissemination. Ten variables (predictors) were selected for T.s.e. modelling. These were four bioclimatic (BIO1 = Annual Mean Temperature, BIO10 = Mean Temperature of Warmest Quarter, BIO11 = Mean Temperature of Coldest Quarter and BIO12 = Annual Precipitation), three topographic (altitude, slope and the compound topographical index (CTI)), and three human variables (pet shop density, distance to urban areas and human density). To model suitability for T.s.e. establishment we tested four combinations of three sets of descriptor variables (human, environmental and both), with two types of occurrence records (reproductive or all records), at a global (worldwide) or regional scale (Iberian Peninsula (IP)). For each combination, an ensemble of niche-based models (NBMs) was built using nine different types of models implemented in BIOMOD2. In worldwide modelling, the use of reproductive occurrence records enables the most accurate predictions. At a regional scale, the combination of environmental and human variables promotes higher accuracy than using human variables alone. For worldwide and regional modelling, the most important variables are associated with temperature (Mean Temperature of Coldest Quarter; Annual Mean Temperature; Mean Temperature of Warmest Quarter). For regional modelling the human variable with highest importance was human density. Our approach may be useful for the management of released pet invaders, namely identifying high invasion risk areas where management efforts should be prioritized. From our models we recommend that T.s.e. management efforts should be prioritized to coastal and lowland areas. This study highlights that when modelling invasive species distributions, it is very important to use records that accurately represent species establishment (e.g. species breeding). Moreover, it clarified that variables associated to propagule pressure can improve model performance, even though these are much less used than bioclimatic variables. This modelling framework may be applied to other invasive species with different invasion pathways, by using different variables, directly linked with the respective invasion vectors and taking into account anthropogenic pressure. These modelling procedures should provide a better view of areas at risk of invasion, should improve management efforts and should also provide important insights on the role of human vectors on the shaping of invasive species distribution.

In this work, the presence of the channel catfish Ictalurus punctatus in the Portuguese section of the Guadiana drainage (Iberian Peninsula) is confirmed based on morphological and molecular species identification. The spatial and temporal dispersal of this non-native catfish was also reconstructed for the Guadiana drainage, based mostly on online fishermen records with minor contributions from the few scientific reports available. The obtained records (mainly from angling fora) span the period since the species' first reported presence in Iberia (1980s) up to the present, and support a westward invasion pattern of non-native fish (NNF) reported for the Iberian fish invasion hotspot. The invasion pathway is driven mainly by natural dispersal downstream at a rate between 8 and 42 km per year. Yet, at least four introduction events within the Guadiana drainage can unambiguously be assigned to human translocations after the initial human-mediated introduction. The present study reinforces the usefulness and relevance of using validated on-line fishermen records, provides a more complete and updated distribution range of NNF species and enables assessment of their dispersal patterns. This is of particular importance because it allows near real-time monitoring of NNF dispersal, including first occurrences of NNF, at minimal cost., Dans ce travail, la présence du poisson-chat Ictalurus punctatus dans la partie portugaise du bassin hydrographique du Guadiana (Péninsule Ibérique) est confirmée sur la base de l'identification morphologique et moléculaire de l’espèce. La dispersion spatiale et temporelle de ce poisson-chat non indigène a également été reconstituée pour le bassin du Guadiana, en se basant principalement sur des articles en ligne de pêcheurs, avec des contributions mineures provenant des quelques rapports scientifiques disponibles. Les enregistrements obtenus (principalement à partir de forums de pêche à la ligne) couvrent la période depuis la première présence signalée de l'espèce en Péninsule Ibérique (1980) jusqu' à aujourd'hui, et confirment un schéma d'invasion vers l'ouest des poissons non indigènes (NNF) signalé par le hotspot d'invasion des poissons ibériques. La voie d'invasion est faite principalement par la dispersion naturelle en aval, à un rythme de 8 à 42 km par année. Cependant, au moins quatre événements d'introduction dans le bassin hydrographique du Guadiana peuvent être attribués sans ambiguïté à des translocations humaines après l'introduction initiale par l'homme. La présente étude renforce l'utilité et la pertinence d'utiliser des informations en ligne validées de pêcheurs, afin de fournir une carte de distribution plus complète et mise à jour des espèces de poissons non indigènes et d'évaluer leurs modèles d'invasions. Ceci est d'une importance particulière, car il permet une surveillance quasi en temps réel de la dispersion des NNF, y compris les premières occurrences de NNF, et ce, presque gratuitement.

Freshwater crustaceans are known to disperse overland, aiding the invasion of new environments. To analyze the effect of environmental variables (humidity, temperature, illuminance, vegetation, and slope) on the movement direction of Eriocheir sinensis (H. Milne Edwards, 1853), Pacifastacus leniusculus (Dana, 1852) and Procambarus clarkii (Girard, 1852) in land, the animals were placed at the centre of a metal gutter and given a choice between two values of each variable. Chi-squared tests revealed significant preferences for E. sinensis to move downhill, P. leniusculus to move toward cooler areas and P. clarkii to move downhill and toward cooler areas. To test the ability of P. leniusculus and P. clarkii (E. sinensis was not present at the testing site) to return to water, they were placed in a circular arena near the river bank and their direction of movement was recorded. Chi-squared tests revealed that P. leniusculus, when isolated and in groups of 6, showed a significant tendency to move downstream, but not directly toward the water. P. clarkii showed no significant preference in movement direction. Since movement direction and overland dispersal are influenced by environmental gradients of temperature and elevation, these variables are fundamental for predicting autonomous overland dispersal and colonization patterns.

The red swamp crayfish ( Procambarus clarkii ) is a freshwater invasive species which has become a worldwide problem. Recent work on ectozoochory of freshwater macrocrustacean species indicated that there might be a possibility of transport of recently-hatched crayfish by birds. In this context, we applied a new set of methods to quantify the probability of transport of recently-hatched crayfish, namely with moving animal vectors. First, we tested the desiccation resistance of crayfish and the capacity of crayfish to cling to mallard's feet, depending on the standing time of the feet. We also determined the ability of recently-hatched crayfish to cling to an artificially moving freshly dead mallard ( Anas platyrhynchos ) and finally, we determined the time required for the death of 50% and 90% of the individuals of recently-hatched crayfish under conditions similar to those of mallard flight. Recently-hatched crayfish were able to survive up to 225 min out of water, withstanding longer at a lower temperature and therefore transport does not seem to be limited by desiccation survival. The duration of the standing period of duck's feet positively affected the probability of transport of crayfish. Recently-hatched crayfish were able to cling to a moving duck and the probability of clinging was significantly affected by the water depth, being lower at greater depths. Moreover, when transported on a freshly dead duck under flight simulation conditions the time required for the death of 50% and 90% of the individuals were 2 min 14 s and 4 min 53 s, respectively. These flight durations correspond to transport distances of 2.8 km and 6.1 km, respectively, which is enough for transport to another aquatic system. The results demonstrate that passive transport of recently hatched P. clarkii by actively moving waterbirds is possible, and therefore it will likely enhance the local process of invasion.

The red swamp crayfish (Procambarus clarkii) and the bladder snail (Physella acuta) are two invasive aquatic macroinvertebrate species with worldwide distribution that are plagues in rice fields. The purpose of this study was to investigate the possibility of accidental human dispersal of these two species by off-road vehicles. An experimental approach was used owing to the difficulty of obtaining field data on low-probability events such as passive dispersal. Experiments were performed testing the probability of attachment of both organisms to mudguards of off-road vehicles as well as successful transport and release into the receiver water body. Recently-hatched P. clarkii and all P. acuta sizes available in the field were used. Results showed that P. clarkii and P. acuta can be transported in mud adhering to an off-road vehicle. No differences were found in the proportions of adhered organisms between species or for each species at the different densities used because of low overall retrieval. For P. acuta, the attachment probability varied between 0.5% both for 50 and 200 individuals m-2 and 1% for 100 ind. m-2. For P. clarkii, no individuals adhered at 50 ind. m-2, but the probabilities were 1% and 1.5% for 100 and 200 ind. m-2, respectively. A transport-survival experiment showed a mean survival distance of 83.2 km for P. clarkii and 92.2 km for P. acuta under dry conditions. Rain or wet conditions severely reduced successful transport. The proportion of organisms falling into a receiving water body increased with the vehicle's speed while crossing the water. Although the results demonstrated a low probability of occurrence of attachment, they also showed that, if attachment occurs, aquatic organisms have a high chance to be released successfully in a suitable environment after long-distance transport by vehicle. Copyright © 2014 John Wiley & Sons, Ltd.

International audience; Procambarus 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.

Effective management of invasive fishes depends on the availability of updated information about their distribution and spatial dispersion. Forensic analysis was performed using online and published data on the European catfish, Silurus glanis L., a recent invader in the Tagus catchment (Iberian Peninsula). Eighty records were obtained mainly from anglers’ fora and blogs, and more recently from www.youtube.com. Since the first record in 1998, S. glanis expanded its geographic range by ≈700 km of river network, occurring mainly in reservoirs and in high-order reaches. Human-mediated and natural dispersal events were identified, with the former occurring during the first years of invasion and involving movements of >50 km. Downstream dispersal directionality was predominant. The analysis of online data from anglers was found to provide useful information on the distribution and dispersal patterns of this non-native fish, and is potentially applicable as a preliminary, exploratory assessment tool for other non-native fishes. info:eu-repo/semantics/publishedVersion

The river shrimp Athyaephyra desmaresti is a Mediterranean species which in recent years expanded its distribution, colonizing rivers of central Europe. The purpose of this study was to investigate the possibility of passive external dispersal of the river shrimp Athyaephyra desmaresti by waterfowl. We performed experiments testing shrimp desiccation survival, probability of attachment to waterfowl, and probability of successful transport. We found that in the laboratory 10% of the river shrimps can survive out of water for up to 90.1 min, but this period was reduced to 18.5 min under simulated bird flight conditions. Two different outdoor experiments simulating bird flight conditions indicated a 50% probability of successful transport on flight distances over 15 km. Our results using dead ducks show evidence that small, large or ovigerous river shrimps can attach to and be transported by ducks and that this capacity is affected by water depth. This study demonstrated that waterbird-mediated passive dispersal of river shrimps can occur and may be important for genetic flows between populations and for the colonization of new sites.

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.

Key-words: Biological invasions, angling, freshwater introductions, invasive fish This work reports for the first time the presence of a non-native fish, the European Perch (Perca fluviatilis), in continental Portugal. The presence of this species was first reported on an angling web forum and its occur- rence was scientifically confirmed later in a small reservoir of the Tagus river basin, located in the central region of Portugal. The importance of the angling web forums as a useful tool to help detection of non-native fish species introductions and their potential for education on biological invasions is discussed.

Key-words: Pacifastacus leniusculus, Procambarus clarkii, desiccation survival, invasive species, dispersal The 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 LT90 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.

Human transport and active dispersal of the red swamp crayfish (Procambarus clarkii) con- tribute to its rapid spread. However, some small aquatic organisms can be transported by birds. We made two hypotheses related to waterbird-mediated passive dispersal of juvenile crayfish. The first is that, depending on water depth, recently hatched crayfish can attach to ducks, initiating passive external trans- port (i.e., ectozoochory). The second is that recently hatched crayfish can survive bird flight, being affected by crayfish features, flight distance, and environmental conditions. A first experiment tested the attachment of juvenile crayfish to ducks at different water depths by using a freshly dead duck and tanks with crayfish. Another set of three experiments tested crayfish survival during air transportation. To simulate bird flight, we first used a vehicle moving at bird flight speed, and we then used trained pigeons. Several flight distances, environmental conditions, and crayfish sizes were tested. Our results showed that juvenile crayfish were capable of clinging to duck feathers and were transported when ducks were removed from the water. Furthermore, some juveniles of P. clarkii were able to survive long-distance transport when sus- pended outside a moving vehicle or when transported by birds. The probability of success was affected by water depth, crayfish size, distance travelled, and relative humidity. Our results support the occurrence of passive transportation of this invader by means of attachment to birds. These findings indicate that waterbird-mediated passive dispersal should be taken into account to explain P. clarkii's rapid spread and should be considered when managing its invasions.

Most studies of biological invasions refer to the human role in species dispersal but the importance of ectozoochory has scarcely been studied. Thus, we investigated whether the first alien amphipod species found in the Iberian Peninsula, North American Crangonyx pseudogracilis can be dispersed by waterfowl. To do this, we showed experimentally that the amphipod may cling to the plumage and legs of a mallard duck (Anas platyrhynchos) and be transported under controlled laboratory conditions. The probability of the amphipods being transported on duck’s plumage or feet is 1.84 and 1.6%, respectively. Another experiment showed that C. pseudogracilis may stay attached to a flying duck and survive during its flight for a distance of 6.8 km. In addition, we found that this invader can stay alive with a LT90 of 88.6 min when exposed to desiccation. Thus, we conclude that C. pseudogracilis may be successfully transported by the waterfowl for short distances to other waterbodies. Thus, ectozoochory may be an important way of spreading the amphipods in areas where the hydrological network is poorly developed and not interconnected with artificial canals.

In the south of Portugal there are only two species of strictly freshwater decapods: the native freshwater shrimp Atyaephyra desmarestii and the exotic crayfish Procambarus clarkii. The aim of this study is to understand if the exotic crayfish acts as river shrimp predator and if both species share the same type of microhabitat. We performed laboratory experiments to study predation and conducted field work in the river Sorraia to verify the microhabitat distribution of both species. Laboratory experiments demonstrated significant predation on river shrimp for crayfish with a cephalothorax length (CT) over 24 mm. The average daily consumption increases with crayfish CT to a maximum of 0.8 shrimps at 44 mm. Field work confirmed that both species share the same microhabitats although with small differences e.g. on the water quality variables such as conductivity and the percentage of oxygen saturation. These microhabitats are shallow pools with abundant aquatic vegetation with no preference for the type of substrate. In the field, both crayfish density and its cephalothorax length are negatively correlated with shrimp densities. In conclusion, P. clarkii can predate A. desmarestii and the major impacts are expected at high densities of large sized crayfish.

Crangonyx pseudogracilis, a North American crangonyctid amphipod, was found in a stream of Santarém District (Portugal) in September 2011. It is the first record of this species from the Iberian Peninsula. Exact time, mode of introduction and distribution of C. pseudogracilis in the area remain unknown. So far its occurrence was reported only from several countries in north-western Europe. A short overview upon the species general distribution, ecology and invasive potential is provided.