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

-Alien species have been transported and traded by humans for many centuries. However, with the era of globalization, biological invasions have reached notable magnitudes. Currently, introduction of alien species is one of the major threats to biodiversity and ecosystem functioning. The North American crayfish Procambarus clarkii is one of the most widely introduced freshwater species in the world, especially due to its high economic importance. It is responsible for great modifications in invaded environments causing irreparable ecological and economic damages. Its impressive ability to successfully colonize a wide range of environments is a consequence of its behavioural and biological characteristics that can adapt to features of the invaded location, conferring to this species a notable ecological plasticity. This review summarizes the available information regarding P. clarkii's biology and invasive dynamics around the world in order to contribute to the understanding of the threats posed by its establishment, as well as to support management and impact mitigation efforts.

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Aim Understanding the environmental factors determining the establishment of invasive populations is a crucial issue in the study of biological invasions. By taking into account the uncertainty of predictions, ensembles of niche-based models can provide useful information. Therefore, we explored the use of consensus techniques to generate a quantitative description of the environmental conditions favouring the establishment of four problematic invasive decapods: Cherax destructor, Eriocheir sinensis, Pacifastacus leniusculus and Procambarus clarkii.Methods We collected both native and invasive distribution records from multiple sources. From these data, we modelled the potential distribution of the four decapod species using eight correlative models comprising regression, classification and machine learning methods. The relative influence of the environmental variables in single models was averaged to achieve a consensus contribution of the variables. Ecological requirements were investigated by means of consensus suitability curves, a spatial analysis procedure that shows the variation of consensus suitability along the gradients of environmental variables. ResultsThe predictive accuracy of single models ranged from fair to very good. Still, the variability between predictions was high. Similarly, the influence of each variable in different models was also uneven. Consensus analysis identified the variables related to temperature as highly influential for all invaders. Consensus suitability curves show that C. destructor and Procambarus clarkii have reduced suitability in colder areas whereas the suitability for P. leniusculus is greatly reduced in warmer areas. The distance to the ocean was highly influential in E. sinensis models, with suitability showing an exponential decay as distance increased.Main conclusions We show that the information about the species-environment relationships obtained from niche-based models is highly dependent on the characteristics of the models used. In this context, we demonstrate that ensembles of models and consensus approaches can be used to identify such relationships while also allowing the assessment of the uncertainty of the achieved knowledge.

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Please cite this article in press as: Gama, M., et al., Predicting global habitat suitability for Corbicula fluminea using species distribution models: The importance of different environmental datasets. Ecol. Model. (2015), http://dx. a b s t r a c tNiche-based models (NBMs) are increasingly being used to predict the biological distribution of species, as well as the importance of different environmental variables on their habitat adequability. Here, we investigate the reliability of these models in predicting habitat suitability for Corbicula fluminea, an important freshwater bivalve invasive species. In order to determine the influence of topographic vs. climatic variables, three datasets were used: (1) CorbiculaTOPO with topographic variables (altitude, slope and a compound topographical index); (2) CorbiculaMIX, combining climatic (annual mean temperature, mean temperature of warmest quarter, mean temperature of coldest quarter and annual precipitation) and topographic variables and (3) CorbiculaCLIM with only the climatic variables. Nine different types of models, implemented in BIOMOD2, were used and an ensemble of NBMs was built. We aimed to know how climatic suitability for these invaders changes when using different datasets of environmental variables; if the predictive reliability is similar between datasets; and which environmental variables better explain habitat adequability. Model performance was very similar between CorbiculaMIX and Corbicula-CLIM. CorbiculaTOPO was the dataset with the least accurate predictions. Mean temperature of the coldest quarter and altitude were the variables that influenced C. fluminea distribution the most. The use of an ensemble of predictions allowed us to clearly identify areas with potential to be invaded by the bivalve, in which records are not yet detected. This information can be used in management, to implement measures to delay or prevent invasions, as well as for the identification of the environmental variables that favor that invasive potential.

1. Global biodiversity is at risk owing to climate change, and freshwater ecosystems are expected to suffer the most. In recent years niche-based models (NBMs) have been used to predict species distribution and are an important tool for conservation and management of aquatic ecosystems. In this work, the current and future climatic suitability areas of the invasive species Corbicula fluminea, which has known adverse ecological and economic impacts, were investigated.2. The species distribution modelling was based on nine algorithms in BIOMOD2, summarized in an ensemble forecasting approach. To model the species distribution, eight climatic parameters related to temperature and precipitation variables were considered. Three time frames (current, 2050 and 2070) were modelled using four increasing CO 2 emission scenarios.3. The performance of individual models was excellent according to the area under the receiver operating characteristic curve (AUC) and good to excellent according to true skill statistics (TSS). Annual mean temperature, minimum temperature of the coldest month and mean temperature of the coldest quarter were the most important variables predicting C. fluminea occurrence. Of the total continental area, 6.6% was predicted to be suitable for C. fluminea in current conditions. 4. In the future, suitable area will increase from the current value of 6.6% to values from 9.4% to 12.6%, according to the 2050 projections and up to 12.7% in 2070 in high emission scenarios. 5. Overall, the results indicate that climate change will favour the expansion of C. fluminea into new river basins, especially at higher latitudes, and that future climatic scenarios may double the suitable area for Corbicula fluminea.

Recently, there has been much debate whether niche based models (NBM) can predict biological invasions into new areas. These studies have chiefly focused on the type of occurrence data to use for model calibration. Additionally, pseudo‐absences are also known to cause uncertainty in NBM, but are rarely tested for predicting invasiveness. Here we test the implications of using different calibration sets for building worldwide invasiveness models for four major problematic decapods: Cherax destructor, Eriocheir sinensis, Pacifastacus leniusculus and Procambarus clarkii. Using Artificial Neural Networks models we compared predictions containing either native range occurrences (NRO), native and invasive occurrences (NIO) and invasive only (IRO) coupled with three types of pseudo‐absences – based on sampling only 1) the native range (NRA), 2) native and invasive ranges (NIA), and 3) worldwide random (WRA). We further analysed the potential gains in accuracy obtained through averaging across multiple models. Our results showed that NRO and IRO provided the best predictions for native and invaded ranges, respectively. Still, NIO provided the best balance in predicting both ranges. Pseudo‐absences had a large influence on the predictive performance of the models, and were more important for predictiveness than types of occurrences. Specifically, WRA performed the best and NRA and NIA performed poorly. We also found little benefit in combining predictions since best performing single‐models showed consistently higher accuracies. We conclude that NBM can provide useful information in forecasting invasiveness but are largely dependent on the type of initial information used and more efforts should be placed on recognizing its implications. Our results also show extensive areas which are highly suitable for the studied species worldwide. In total these areas reach from three to nine times the species current ranges and large portions of them are contiguous with currently invasive populations.