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Invasive alien species are one of the major threats to global biodiversity, ecosystem integrity, nature’s contribution to people and human health. While scenarios about potential future developments have been available for other global change drivers for quite some time, we largely lack an understanding of how biological invasions might unfold in the future across spatial scales.Based on previous work on global invasion scenarios, we developed a workflow to downscale global scenarios to a regional and policy-relevant context. We applied this workflow at the European scale to create four European scenarios of biological invasions until 2050 that consider different environmental, socio-economic and socio-cultural trajectories, namely the European Alien Species Narratives (Eur-ASNs).We compared the Eur-ASNs with their previously published global counterparts (Global-ASNs), assessing changes in 26 scenario variables. This assessment showed a high consistency between global and European scenarios in the logic and assumptions of the scenario variables. However, several discrepancies in scenario variable trends were detected that could be attributed to scale differences. This suggests that the workflow is able to capture scale-dependent differences across scenarios.We also compared the Global- and Eur-ASNs with the widely used Global and European Shared Socioeconomic Pathways (SSPs), a set of scenarios developed in the context of climate change to capture different future socio-economic trends. Our comparison showed considerable divergences in the scenario space occupied by the different scenarios, with overall larger differences between the ASNs and SSPs than across scales (global vs. European) within the scenario initiatives.Given the differences between the ASNs and SSPs, it seems that the SSPs do not adequately capture the scenario space relevant to understanding the complex future of biological invasions. This underlines the importance of developing independent, but complementary, scenarios focused on biological invasions. The downscaling workflow we presented and implemented here provides a tool to develop such scenarios across different regions and contexts. This is a major step towards an improved understanding of all major drivers of global change including biological invasions.

Future dynamics of biological invasions are highly uncertain because they depend on multiple environmental, societal and socio-economic drivers. We adopted a qualitative scenario approach to explore the future of invasive alien species (IAS) in Europe and created an overall strategy for their management that considers different plausible future developments. The scenarios and strategy were developed during two online workshops with a multidisciplinary team of experts. First, we downscaled four global scenarios of biological invasions to the European level. Second, we developed a management strategy structured into 19 goals that cover a broad array of IAS-related topics (i.e. policy, research, public awareness and biosecurity), and provided solutions for achieving these goals considering the European scenarios. Third, we identified four interrelated recommendations around which any long-term strategy for managing IAS in Europe can be structured: (i) a European biosecurity regime, (ii) a dedicated communication strategy, (iii) data standardization and management tools, and (iv) a monitoring and assessment system. Finally, we identified the feasibility of the IAS management strategy, finding strong differences among the four scenarios. High levels of technological development, public environmental awareness, and effectiveness of IAS policies facilitated the implementation of the overall management strategy. Together, our results indicate that it is time for a new management of biological invasions in Europe based on a more integrative perspective across sectors and countries to be better prepared for future challenges.

9 pages, 7 figures, The Atlantic blue crab (Callinectes sapidus) has rapidly invaded coastal environments in the western Mediterranean, but there is no consistent assessment of its impacts yet. We use interviews and long-term data series in the Ebro Delta (NE Spain) to: i) characterise the evolution of the blue crab invasion; and ii) identify its impacts. The blue crab was first recorded in 2012, but its expansion started around 2016, with an exponential increase in abundance between 2017 and 2018. Aquatic communities have tended to be dominated by the blue crab, coinciding with the steep and consistent declines of several species, including threatened and commercially exploited ones. Blue crab impacts seem to be exerted even at low abundances, arguably hindering the recovery of declining species. The blue crab is becoming a keystone species in invaded systems and efforts should be made to understand its many-folds impacts in order to prevent or mitigate them, This work is part of the project Crayfish invasions across time and space, a multidisciplinary approach (PID2020-120026RB-I00) funded by the Spanish Ministerio de Ciencia e Innovación, which also supported R.B-M. through Belmont Forum-BiodivERsA project InvasiBES (PCI2018-092939), and PA through project CLIFISH CTM2015-66-400-C3-3-R and the “Severo Ochoa Centre of Excellence” accreditation to ICM-CSIC (CEX2019-000928-S)

According to the competitive exclusion principle, species with low competitive abilities should be excluded by more efficient competitors; yet, they generally remain as rare species. Here, we describe the positive and negative spatial association networks of 326 disparate assemblages, showing a general organization pattern that simultaneously supports the primacy of competition and the persistence of rare species. Abundant species monopolize negative associations in about 90% of the assemblages. On the other hand, rare species are mostly involved in positive associations, forming small network modules. Simulations suggest that positive interactions among rare species and microhabitat preferences are the most probable mechanisms underpinning this pattern and rare species persistence. The consistent results across taxa and geography suggest a general explanation for the maintenance of biodiversity in competitive environments., J.C. is supported by the Carl Tryggers Foundation for Scientific Research (no. CTS 16:384). E.A. is supported by a postdoctoral grant (no. CT39/17) funded by the Universidad Complutense de Madrid. C.J.M. is supported by the Swiss National Science Foundation (grant no. SNSF-31003A-144162). R.B.-M. is supported by the Spanish Ministry of Science and Innovation predoctoral fellowship no. BES-2013-065753. M.S., J.A.B.-C. and J.M.-G. acknowledge support from the University of Geneva (project: C-CIA; no. 309354). X.A. is supported by a Ramón y Cajal research contract by the Spanish Ministry of Economy and Competitiveness (MINECO, no. RYC-2015-18448). M.R. is supported by the Swedish Research Council grant no. 2016-00796. J.A.N. was supported by a Colombian COLCIENCIAS doctoral scholarship (no. 617-2013). F.A.-M. is grateful to CAPES for a doctoral scholarship (no. 120147/2016-01). A.L., P.F. and J.M.-G. were funded by the AGORA Project (MINECO, no. CGL2016-77417-P). C.M.-M. was supported by an IdEx Bordeaux Postdoctoral Fellowship (VECLIMED project). A.H. was supported by the University of Alcalá own research programme 2018 postdoctoral grant and Basque Country Government funding support to FisioClimaCO2 (IT1022-16) research group. L.J. received productivity grants from of CNPq (process no. 307597/2016-4).

Social networks are the result of interactions between individuals at different temporal scales. Thus, sporadic intergroup encounters and individual forays play a central role in defining the dynamics of populations in social species. We assessed the rate of intergroup encounters for three western lowland gorilla ( Gorilla gorilla gorilla ) groups with daily observations over 5 years, and non-invasively genotyped a larger population over four months. Both approaches revealed a social system much more dynamic than anticipated, with non-aggressive intergroup encounters that involved social play by immature individuals, exchanges of members between groups likely modulated by kinship, and absence of infanticide evidenced by infants not fathered by the silverback of the group where they were found. This resulted in a community composed of groups that interacted frequently and not-aggressively, contrasting with the more fragmented and aggressive mountain gorilla ( G. beringei beringei ) societies. Such extended sociality can promote the sharing of behavioural and cultural traits, but might also increase the susceptibility of western lowland gorillas to infectious diseases that have decimated their populations in recent times.

Human activity leading to both species introductions and extinctions is widely known to influence diversity patterns on local and regional scales. Yet, it is largely unknown whether the intensity of this activity is enough to affect the configuration of biodiversity at broader levels of spatial organization. Zoogeographical regions, or zooregions, are surfaces of the Earth defined by characteristic pools of species, which reflect ecological, historical, and evolutionary processes acting over millions of years. Consequently, it is widely assumed that zooregions are robust and unlikely to change on a human timescale. Here, however, we show that human-mediated introductions and extinctions can indeed reconfigure the currently recognized zooregions of amphibians, mammals, and birds. In particular, introductions homogenize the African and Eurasian zooregions in mammals; reshape boundaries with the reallocation of Oceania to the New World zooregion in amphibians; and divide bird zooregions by increasing biotic heterogeneity. Furthermore, the combined effect of amphibian introductions and extinctions has the potential to divide two zooregions largely representing the Old and the New World. Interestingly, the robustness of zooregions against changes in species composition may largely explain such zoogeographical changes. Altogether, our results demonstrate that human activities can erode the higher-level organization of biodiversity formed over millions of years. Comparable reconfigurations have previously been detectable in Earth’s history only after glaciations and mass extinction events, highlighting the profound and far-reaching impact of ongoing human activity and the need to protect the uniqueness of biotic assemblages from the effects of future species introductions and extinctions.

Exposed sandy beaches are widespread coastal habitats with temporal and spatial variability. O Rostro beach (Galicia, north-west Spain) was the most severely affected beach in the ‘Prestige’ oil spill (November 2002). Monitoring sampling was conducted to study macroinfaunal composition and structure after the oil spill episode. The purpose of this survey was to characterize macroinfaunal variations on the beach over a yearly scale (2003–2007) and determine the recovery period. These data are compared with the only available data collected before the spill (1995). Two zones where identified with different recovery trends: (1) supralittoral, occupied either by talitrid amphipods, oniscoidean isopods and insects; and (2) intertidal, where marine crustaceans prevailed. Beach morphodynamics partially buried the oil, which gradually reappeared and was dragged to the coast. Negative ecological effects were observed in the short term (six months after the 2002 spill) but macroinfauna apparently recovered in the following years (2004–2007), showing that macroinfaunal assemblages of this beach are resilient enough to recover after severe stress.

The suprabenthos is considered a major food resource for some fish and birds. Moreover, it plays a key role in the food chain and in nutrient regeneration in the surf zone. The aim of this study was to determine the factors that regulate this fauna and the differences between the suprabenthic groups, to study the possibility of seasonal variations and to compare these results with those of other studies conducted in Europe. A study and geographical comparison was conducted of the temporal patterns of the suprabenthos in the swash zone at two sandy beaches on the NE Atlantic coast (Altar and Ladeira beaches) in the NW of Spain. The study was carried out from September 2005 to August 2007 (24 months). To study the fauna, 60 m 2 was sampled monthly with a suprabenthic sledge, and a total of 101 species belonging to Peracarida and Decapoda were recorded. Total densities ranged from 0.42 ind·m − 2 to 178.75 ind·m − 2 . Ladeira beach showed higher densities and species richness than Altar beach, and the biocoenosis showed a different dynamic over the 24 months and between years and locations. These results indicate that there is no clear seasonality in the dynamic of suprabenthic species, although the variance of Peracarida orders was explained in diverse degree by environmental variables. The environmental models implemented explained between 27.7% and 93.8% of the faunal data, and hydrodynamic factors and daily global irradiance were selected as the best factors to explain the temporal variations.