Spread Of Invasive Alien Species Research Articles

Modeling population dynamics of invasive pines to optimize their control in native grasslands of Argentina

The spread of invasive alien species over natural environments has become one of the most serious threats to biodiversity and the functioning of ecosystems worldwide. Understanding the population attributes that allow a given species to become invasive is crucial for improving prevention and control interventions. Pampas grasslands are particularly sensitive to the invasion of exotic woody plants. In particular, the Ventania Mountains undergo the advance of alien woody plants; among which the Aleppo pine (Pinus halepensis) stands out due to the extension of the area it covers and the magnitude of the ecological changes associated to its presence. Using a model that describes the population dynamics of the species in the area, we evaluated the expected behavior of the population under different environmental conditions and different management scenarios. When the effect of stochastic fires was simulated, the growth rate was greater than 1 for all the frequencies considered, peaking under fires every nine years, on average. When evaluating the effect of periodic mechanical control of the adult population, the reduction in growth rate was insufficient, except for cutting intensities that significantly exceeded the current operational capacity of the area. Under prescribed fire scenarios, on the other hand, burning frequencies greater than seven years resulted in population reductions. The results highlight the importance of fire in regulating the population of P. halepensis in the Ventania Mountains, with contrasting effects depending on the frequency with which it occurs, which allows considering it as an effective environmental management option for the control of the species.

Short-Term Foredune Dynamics in Response to Invasive Vegetation Control Actions

Efforts to control the spread of invasive alien species (IAS) in coastal dunes are essential to protect biodiversity and maintain the integrity of the ecosystem. However, the timing and extent of these control measures often do not consider their potential impact on dune morphodynamics. This study investigated how IAS control measures can affect sand dune mobility. Research involved monitoring short-term morphological and vegetation changes using close-range remote sensing along with historical wind data. Findings revealed that changes in vegetation cover significantly impacted dune system evolution, notably increasing sand mobility when IAS vegetation was removed. Considering the seasonal wind regime, dominated by offshore winds in the summer, removing vegetation during this period can promote seaward sediment transport, potentially resulting in sediment loss to the beach. These findings highlight the importance of understanding sediment mobility patterns when planning vegetation control actions within dune restoration strategies.

Physiological stress response to urbanisation differs between native and invasive squirrel species

Novel pressures derived from urbanisation can alter native habitats and ultimately impact wildlife. Coping with such human-driven changes might induce shifts in species phenotypic traits, such as physiological responses to anthropogenic stressors. Preadaptation to face those challenges has been suggested to favour settlement and spread of invasive alien species in urbanised areas which, consequently, might respond differently than ecologically similar native species to stressors posed by urbanisation. The activation of the hypothalamic-pituitary-adrenal (HPA) axis and the subsequent release of glucocorticoids (GCs) has been suggested to mediate responses to anthropogenic disturbance in vertebrates. Furthermore, intraspecific competition, in conjunction with stressors related to urbanisation, might affect invasive and native species physiological stress responses differently. Using a parallel pseudo-experimental study system we measured faecal glucocorticoid metabolite (FGM) concentrations of the native Eurasian red squirrel and the invasive alien Eastern grey squirrel along a rural-urban gradient and in relation to conspecific density. The two species responded differently to challenges posed by the synergic effect of urbanisation and intraspecific competition. Association of FGMs and conspecific density in native red squirrels varied between rural and suburban sites, potentially depending on differential HPA axis responses. In urban sites, this relationship did not differ significantly from that in rural and suburban ones. Conversely, invasive grey squirrels' FGMs did not vary in relation to conspecific density, nor differed along the rural-urban gradient. Improving knowledge about native and competing invasive species' physiological responses to anthropogenic stressors can support conservation strategies in habitats altered by man. Our findings suggested that the invasive squirrels might be preadapted to cope with these challenges in urbanised areas, potentially increasing their success under the future global change scenario.

A novel deep learning‐based bioacoustic approach for identification of look‐alike white‐eye (Zosterops) species traded in wildlife markets

The songbird trade crisis in East and South East Asia has been fuelled by high demand, driving many species to the brink of extinction. This demand, driven by the desire for songbirds as pets, for singing competitions and for prayer animal release has led to the overexploitation of numerous species and the introduction and spread of invasive alien species and diseases to novel environments. The ability to identify traded species efficiently and accurately is crucial for monitoring bird trade markets, protecting threatened species and enforcing wildlife laws. Citizen scientists can make major contributions to these conservation efforts but may be constrained by difficulties in distinguishing ‘look‐alike’ bird species traded in markets. To address this challenge, we developed a novel deep learning‐based Artificial Intelligence (AI) bioacoustic tool to enable citizen scientists to identify bird species traded in markets. To this end, we used three major avian vocalization databases to access bioacoustic data for 15 morphologically similar White‐eye (Zosterops) species that are commonly traded in Asian wildlife markets. Specifically, we employed the Inception v3 pre‐trained model to classify the 15 White‐eye species and ambient sound (i.e. non‐bird sound) using 448 bird recordings we obtained. We converted recordings into spectrogram (i.e. image form) and used eight image augmentation methods to enhance the performance of the AI neural network through training and validation. We found that recall, precision and F1 score increased as the amount of data augmentation increased, resulting in up to 91.6% overall accuracy and an F1 score of 88.8% for identifying focal species. Through the application of bioacoustics and deep learning, this approach would enable citizen scientists and law enforcement officials efficiently and accurately to identify prohibited trade in threatened species, making important contributions to conservation.

Global spatial distribution of Prosopis juliflora -one of the world's worst 100 invasive alien species under changing climate using multiple machine learning models.

Climate change is one of the factors contributing to the spread of invasive alien species. As a result, it is critical to investigate potential invasion dynamics on a global scale in the face of climate change. We used updated occurrence data, bioclimatic variables, and Köppen-Geiger climatic zones to better understand the climatic niche dynamics of Prosopis juliflora L. (Fabaceae). In this study, we first compared several algorithms-MaxEnt, generalized linear model (GLM), artificial neural network (ANN), generalized boosted model (GBM), generalized additive model (GAM), and random forest (RF)-to investigate the relationships between species-environment and climate for mesquite. We identified the global climate niche similarity sites (NSSs) using the coalesce approach. This study focused on the current and future climatic suitability of P. juliflora under two global circulation models (GCMs) and two climatic scenarios, i.e., Representative Concentration Pathways (RCPs), 4.5 and 8.5, for 2050 and 2070, respectively. Sensitivity, specificity, true skill statistic (TSS), kappa coefficient, and correlation were used to evaluate model performance. Among the tested models, the machine learning algorithm random forest (RF) demonstrated the highest accuracy. The vast swaths of currently uninvaded land on multiple continents are ideal habitats for invasion. Approximately 9.65% of the area is highly suitable for the establishment of P. juliflora. Consequently, certain regions in the Americas, Africa, Asia, Europe, and Oceania have become particularly vulnerable to invasion. In relation to RCPs, we identified suitable area changes (expansion, loss, and stability). The findings of this study show that NSSs and RCPs increase the risk of invasion in specific parts of the world. Our findings contribute to a cross-border continental conservation effort to combat P. juliflora expansion into new potential invasion areas.

Biological invasions in intermittent rivers and streams: current knowledge, and future frontiers

Intermittent rivers and ephemeral streams (IRES) have been overlooked in invasion science as the characteristic drying - wetting regimes are assumed to be a barrier to invasion processes. Flow contraction/cessation limits the persistence and success of water-dependent invasive alien species (IAS) in most IRES, while flash floods may restrict limnophilic and strictly terrestrial ones. However, IRES are subject to multiple anthropogenic stressors that could ultimately favour the arrival and spread of IAS and their mosaic of dynamic habitats may theoretically support both terrestrial and aquatic IAS. Successful IAS are characterised by adaptations, traits and life histories which facilitate rapid, opportunistic exploitation of habitats and resources. Here, the potential invasibility of IRES is discussed along with a summary of current knowledge gaps, examples and challenges across different continents. IAS in IRES should be considered a cause for concern but also an intriguing study system to understand the mechanics of biological invasions under global change.

Kudzu vine (Pueraria montana var. lobata, Fabaceae): Invasive alien species of Union concern (EU Regulation 1143/2014) in Croatia

AbstractKudzu vine (Pueraria montana var. lobata; Fabaceae) was included on the list of invasive alien species of (European) Union concern in 2016, according to EU Regulation 1143/2014 on the prevention and management of the introduction and spread of invasive alien species. In the Flora Croatica Database this species is recorded under its synonym Pueraria thunbergiana Benth. for Split (Central Dalmatia), so its presence in Croatia was overlooked until it was discovered in Malinska on the island of Krk in August 2018. Recent field observations confirm that, in addition to Malinska, it is also present in Šestanovac (Central Dalmatia), the Trsteno Arboretum and in Dubrovnik (South Dalmatia). Localities in Gradac and Seget (Central Dalmatia) were also recently discovered. Literature and herbaria data as well as internet resources indicate that kudzu vine has been historically grown as an ornamental species in Croatia. Considering its invasiveness as reported in several countries and its ornamental uses, other unknown localities of cultivated or naturalized kudzu vine could exist along the Croatian coast.

Germany’s first Action plan on the pathways of invasive alien species to prevent their unintentional introduction and spread

The increase in global trade and traffic networks contributes to the introduction and spread of invasive alien species, posing a threat to biodiversity. EU Regulation 1143/2014 addresses the prevention and management of invasive alien species and requires an action plan on the priority pathways of unintentional introduction and spread of invasive alien species by each member state. To this end, the first German action plan was developed for the German government in cooperation with relevant Ministries and authorities, scientists, administrative experts, stakeholder working groups and political as well as public deliberation processes. As a result, 14 priority pathways of unintentional introduction, escape or release and spread were identified, resulting in 24 targeted measures. Nineteen sectors will be involved in the implementation of these measures. Here we describe the development process and outcome of Germany’s first action plan. By this, we aim making the process public and transparent, which can facilitate a revision of the action plan required at least every six years, and trigger broader European as well as national cooperation in the future.

Local community perception towards invasive alien plant species utilization in Bodogol – Gunung Gede Pangrango National Park

The spread of invasive alien species in Gunung Gede Pangrango National Park is considered causes disturbance and damage threats to ecosystems, habitats, and native plant species. There are three invasive alien plant species spread in Bodogol area, a part of Gunung Gede Pangrango National Park, namely Maesopsis eminii, Calliandra calothyrsus, and Austroeupatorium inulifolium. Two out of these three species, i.e Maesopsis eminii and Calliandra calothyrsus are well known as useful plants and have a high Index Cultural Significance (ICS). In 2019 a study was conducted to quantify the perception of the community in Bodogol towards Maesopsis eminii and Calliandra calothyrsus utilization. Data were collected through interview and filling out questionnaire by 42 respondents using tri-stimulus amar framework. The results of the study obtained total value of quantifying the perception is 2.24 out of 4.00 in Likert’s scale. The value shown that community in Bodogol had positive perception towards these invasive alien plant species. The factors that affected community perceptions are the level of knowledge about invasive species and the benefits of the species. Therefore, this study is important as input for decisions in determining appropriate management of invasive species in Gunung Gede Pangrango National Park area.

Predicting the spatio-temporal distribution of the invasive alien plant Andropogon virginicus, in the South Korean peninsula considering long-distance dispersal capacities.

The spread of invasive alien species is a major threat to biodiversity. Estimating the long-distance dispersal capacity of invasive alien plants is vital for understanding their population dynamics and community composition. We predicted the spatial-temporal distribution of the alien plant Andropogon virginicus, in the Korean peninsula under climate change scenario using Random Forest (RF) and Cellular Automaton (CA) methods. Land use, barriers to dispersal, long-distance dispersal frequency, and maximum long-distance dispersal range were considered in our analysis. Our results showed that, among the five selected environmental variables, annual mean temperature and Human Foot-Printing (HFP) were positively associated with the occurrence probability of A. virginicus. This suggests that A. virginicus is likely to spread to the disturbed northern part of the Korean Peninsula due to climate change and habitat preference. When comparing modeling results for dispersal to field survey data, the modeling raster sets drawn from the long-distance dispersal frequency of 0.05 and maximum long-distance dispersal distance of 30 km y-1 had the most similar spatial expansion among the six long-distance dispersal parameter sets. The dispersal directions were associated with the landscape. Specifically, seeds dispersed by wind (anemochorous seeds) could propagate into open landscapes more easily than in forests. Regarding A. virginicus management, this grass can quickly invade bare ground with their wind-dispersed seeds, therefore habitat destruction, such as excessive logging and weeding, should be restrained.

Towards Improved Data Flows for the Management of Invasive Alien Species and Wildlife: A LIFE RIPARIAS use case

Invasive alien species (IAS) are recognised as a major threat to biodiversity. To prevent the introduction and spread of IAS, the European Union Regulation (EU) 1143/2014 imposes an obligation on Member States to both develop management strategies for IAS of Union Concern and report on those interventions. For this, we need to collect and combine management data and streamline management actions. This is still a major challenge: the landscape of IAS management is diverse and includes different authorities, managers, businesses and non-governmental organizations. Some organizations have developed their own specific software applications for recording management actions. For other organizations, such a software system is lacking. Their management data are scattered, not harmonized, and often not openly available. For EU reporting, a workflow is needed to centralize all information about the applied management method, management effort, cost, effectiveness and impact of the performed actions on other biota or the environment. At this moment, such a workflow is lacking in Belgium. One of the aims of the LIFE RIPARIAS project is to set up a workflow for harmonizing IAS management data in Belgium. Based on the input from the IAS management community in Belgium, we were able to: draft a community-driven data model and exchange format called manIAS (MANagement of Invasive Alien Species, Reyserhove et al. 2022), and identify the minimal requirements a software application should have for being successfully used in the field (Hillaert et al. 2022). draft a community-driven data model and exchange format called manIAS (MANagement of Invasive Alien Species, Reyserhove et al. 2022), and identify the minimal requirements a software application should have for being successfully used in the field (Hillaert et al. 2022). In this presentation, we will explore both outputs, the lessons learned and the way forward. With our work, we aim to facilitate coordination and transfer of information between the different actors involved in IAS and wildlife management, not only on a Belgian scale, but also within an international context.

Invasion genetics of the yellow-legged hornet Vespa velutina in the Westernmost Mediterranean archipelago

AbstractThe yellow-legged hornet (Vespa velutina) is a social Hymenoptera native from Asia and an invasive species in Europe, where it was first detected in France in 2004. Since then, the species has spread across the continent invading mainland Spain and Mallorca island (Balearic archipelago, Western Mediterranean) in 2010 and 2015, respectively. Yellow-legged hornets cause severe damage to ecosystem by predating over a wide variety of pollinators including honeybees. Such a threat situation requires the development of effective management and prevention plans, which can greatly benefit from knowing both the origin and the genetic structure of the invading populations. Here we conduct a genetic study to shed light on both the origin and the phylogenetic relationships of V. velutina populations from Mallorca and mainland Spain using nuclear (STRs) and mitochondrial (cytochrome oxidase c subunit 1) gene markers. Our results show that Mallorca populations originated from invasive European specimens. Moreover, FST values, DAPC and genetic structure analysis suggest two independent incursions in the island with bottleneck and founder effect signatures. Finally, we contribute additional genetic evidence of the polyandrous behavior of this invasive species based on the inference of a mean number of mattings per nest of 3.94 (range 2–6.5). This study supports the human-mediated pathways of this species and highlights the importance of implementing effective biosecurity measures to prevent the spread of invasive alien species in island habitats.

Analysing ecological dynamics with relational event models: The case of biological invasions

AbstractAimsSpatio‐temporal processes play a key role in ecology, from genes to large‐scale macroecological and biogeographical processes. Existing methods studying such spatio‐temporally structured data either simplify the dynamic structure or the complex interactions of ecological drivers. The aim of this paper is to present a generic method for ecological research that allows analysing spatio‐temporal patterns of biological processes at large spatial scales by including the time‐varying variables that drive these dynamics.LocationGlobal analysis at the level of 272 regions.MethodsWe introduce a method called relational event modelling (REM). REM relies on temporal interaction dynamics that encode sequences of relational events connecting a sender node to a recipient node at a specific point in time. We apply REM to the spread of alien species around the globe between 1880 and 2005, following accidental or deliberate introductions into geographical regions outside of their native range. In this context, a relational event represents the new occurrence of an alien species given its former distribution.ResultsThe application of relational event models to the first reported invasions of 4835 established alien species outside of their native ranges from four major taxonomic groups enables us to unravel the main drivers of the dynamics of the spread of invasive alien species. Combining the alien species first records data with other spatio‐temporal information enables us to discover which factors have been responsible for the spread of species across the globe. Besides the usual drivers of species invasions, such as trade, land use and climatic conditions, we also find evidence for species‐interconnectedness in alien species spread.ConclusionsRelational event models offer the capacity to account for the temporal sequences of ecological events such as biological invasions and to investigate how relationships between these events and potential drivers change over time.

Different facets of the same niche: Integrating citizen science and scientific survey data to predict biological invasion risk under multiple global change drivers.

Citizen science initiatives have been increasingly used by researchers as a source of occurrence data to model the distribution of alien species. Since citizen science presence-only data suffer from some fundamental issues, efforts have been made to combine these data with those provided by scientifically structured surveys. Surprisingly, only a few studies proposing data integration evaluated the contribution of this process to the effective sampling of species' environmental niches and, consequently, its effect on model predictions on new time intervals. We relied on niche overlap analyses, machine learning classification algorithms and ecological niche models to compare the ability of data from citizen science and scientific surveys, along with their integration, in capturing the realized niche of 13 invasive alien species in Italy. Moreover, we assessed differences in current and future invasion risk predicted by each data set under multiple global change scenarios. We showed that data from citizen science and scientific surveys captured similar species niches though highlighting exclusive portions associated with clearly identifiable environmental conditions. In terrestrial species, citizen science data granted the highest gain in environmental space to the pooled niches, determining an increased future biological invasion risk. A few aquatic species modelled at the regional scale reported a net loss in the pooled niches compared to their scientific survey niches, suggesting that citizen science data may also lead to contraction in pooled niches. For these species, models predicted a lower future biological invasion risk. These findings indicate that citizen science data may represent a valuable contribution to predicting future spread of invasive alien species, especially within national-scale programmes. At the same time, citizen science data collected on species poorly known to citizen scientists, or in strictly local contexts, may strongly affect the niche quantification of these taxa and the prediction of their future biological invasion risk.

Monitoring of the floristic diversity of the Teremky Tract of the “Holosiivskyi” National Nature Park in the conditions of anthropogenic load

The article presents the results of monitoring the floristic diversity of the Teremky Tract, which is part of the “Holosiivskyi” National Nature Park as a separate territory. The tract is located in the city of Kyiv, directly adjacent to a large residential area and two highways. An analysis of the main factors affecting the ecological state of the territory was conducted. Among the main factors negatively impacting the state of the ecosystem of the Teremky Tract, the following can be distinguished: vandalism, which includes setting fire to old trees and causing various types of damage to them; plucking of flowering plants; environmental pollution with solid household waste; direct and indirect influence of hazardous objects such as boiler plants and gas stations; and the influence of transport infrastructure. The article demonstrates the need for constant monitoring of the ecological state of natural biotopes located within modern megacities. It is shown that the monitoring of floristic diversity, controlling the preservation of valuable and rare plant species, and tracking the appearance and spread of invasive alien species can be effective indicators of the ecological state of the natural biotope. Thus, populations of forest lily (Lilium martagon L.) and cuckoo’s tears (Listera ovata L.) were found on the territory of the Teremky Tract, which are included in the Red Book of Ukraine. Additionally, a group of 400-year-old oak trees grows in this area. However, the presence of invasive alien species such as red oak (Quercus rubra L.), the ash-leaved maple (Acer negundo L.), black cherry (Prunus serotina L.) and Robinia pseudoacacia L. was also observed. Monitoring of floristic diversity in natural biotope areas within megacities plays an important role in timely response to the effects of negative natural and anthropogenic factors for the preservation of the environment of these urban ecosystems. Such monitoring can be conducted both through field observations and using remote methods and analysis of global biodiversity databases such as iNaturalist and GBIF.

Current temperatures limit the potential impact of a commonly traded predatory gastropod

The pet trade has facilitated the spread of invasive alien species (IAS) globally, with negative consequences for biodiversity. The prediction of impacts is a major goal for invasion ecologists, and is especially crucial in an industry often lacking knowledge about traded species. We focused on the predatory gastropod Anentome helena, a species originating in south-east Asia and traded around the world, but with taxonomic uncertainty. We first set out to determine where our study organism fell within the A. “helena” species complex, known to comprise at least four cryptic species, before assessing the effect of temperature on the number of prey, the pulmonate snail Physella acuta, killed per predator via functional response experiments at two temperatures. We used 22 °C as a recommended temperature for housing the species in captivity, and 18 °C as a representative summer lake temperature in temperate climates of Europe. We also assessed the role of predator group size (1×, 2×, 3×) on predation (total consumption and average per capita consumption) at the experimental temperatures with fixed densities of prey, as well as the effect of these temperatures on prey activity. Our organisms belonged to a cryptic species originating from Thailand (Anentome sp. A), matching the findings of aquarium trade samples in other continents. In the functional response experiments, we found maximum feeding rate to be significantly reduced at the lower temperature. A similar result ensued from group feeding, with total consumption significantly reduced and the reduction in average per capita consumption approaching significance at the lower temperature. There was no significant effect of group size on the average per capita consumption in the group trial, indicating neutral conspecific interactions. No significant effect of temperature on the activity of the prey species was found, suggesting decreased consumption was mainly driven by predator, rather than prey. These results suggest limited A. helena impacts in the short-term, but increasing temperatures with climate change may facilitate greater consequences from releases. We suggest future studies assess other potential predatory impacts and survival across relevant abiotic conditions, and encourage the use of similar methods to assess the impacts of other commonly traded species.

A New Horizon-Scanning Tool to Identify Potential Aquatic Invasive Alien Species Introduced into the Baltic Sea by Shipping

Some invasive alien species (IAS) may constitute an important threat to global biodiversity due to major ecological impacts. In 2014, the European Union (EU) introduced a regulation (EU) No 1143/201 on the prevention and management of the introduction and spread of IAS. EU member states are required to carry out an analysis of the introduction and spread of potential IAS in their territories. In the case of aquatic alien species, shipping is considered as the main pathway for their introduction. In this study, a horizon-scanning tool was applied for identifying potential aquatic IAS introduced by shipping into the EU Baltic Sea Region (BSR) countries. This tool has mostly been applied on a country level, but it is more reasonable to study the invasive potentiality at a regional scale, especially for aquatic species that generally disperse over long distances. Individual Baltic countries may also benefit from the results of this study. The result of the horizon-scanning method that we applied produced a list of 27 potential aquatic invaders for the EU BSR countries introduced by international marine and inland shipping. In order, Asia (34% of the species), North America (27% of the species), and Indo-Pacific (23% of the species) were the most frequently listed geographical origins of concern. Marine habitat was the most frequent of the potential IAS, accounting for 41% of the species. Fish (26% of the species), Mollusks (18% of the species), and Crustacea (15% of the species) were the most frequent taxonomic groups. The list of potential IAS was prioritized from highest to lowest probability of invasion (establishment, spread, and impact). Eight species reached the highest probability of invasion. One of the potential IAS, Mytilus galloprovincialis, is native to the Mediterranean Region. These results provide valuable information that policy makers can use to develop more efficient prevention strategies for IAS introduced by shipping into the Baltic Sea.

IDENTIFICATION OF INVASIVE ALIEN SPECIES AND ASSESSMENT OF ECOLOGICAL FACTORS IN THE POOL MALEBO IN KINSHASA, DEMOCRATIC REPUBLIC OF THE CONGO

The aim of this study was to identify invasive aquatic species and assess ecological factors in 5 islands, namely Mipongo, Japon, Kabongo, Kingabwa and Molondo.of the Pool Malebo. A floristic inventory was conducted around these sites and physico-chemical characteristics were measured in each island between 8:00am and 3:00pm using an appropriate electronic probe. The floristic affinity between sites was determined by cluster analysis using MVSP software version 4.03, after highlighting the Jaccard's coefficient based on the presence/absence of species in the different collection sites. The comparison between the sites was carried out using the ANOVA test with SPSS 25 software for physico-chemical parameters. The findings show that 24 species were identified as invasive out of which, six were dominant, namely Eichhornia crassipes, Echinocloa pyramidalis, Pistia stratiotes, Leersia hexandra, Ludwigia abissinega, and Ludwigia sp. No significant differences were observed for the temperature (F=0.42 and p=0.66), conductivity (F=1.55 and p=0.25) and turbidity (F=2.28 and p=0.14) for the three sites. While the pH (F=4.98; p=0.026; LSD=0.361), dissolved oxygen (F=12; p=0.001; LSD=3.65) and salinity (F=4.06; p= 0.04; LSD= 1.69) showed significant variation in the three sites. The formation of vegetation groups around these islands in the Pool Malebo would also be justified by the influence of these parameters. The spread of invasive alien species on the surface of the river needs to draw more attention to scientists, policy makers and government in order to find a way to a good management of these species.

Citizen Science and Phytosanitary Surveillance Systems Are Complementary Tools to Follow the Invasion of Harmonia axyridis.

Citizen science is a valuable tool for early detection, distribution, and spread of invasive alien species (IAS). Nevertheless, citizen science initiatives have several potential biases and may be complemented with long-term structured monitoring schemes. We analyzed the spatial-temporal dynamics of the invasion of Harmonia axyridis (Pallas)(Coleoptera: Coccinellidae) in Chile, based upon two citizen sciences databases (WEB and INAT) and one structured monitoring (SAG). We collected 8638 H. axyridis occurrences between 2009 and 2020. WEB had a higher number of records than SAG and INAT, and in all databases, the number of records has increased over time. The three databases showed that the invasion started in central Chile and then spread toward the north and south. The WEB and SAG recorded occurrences in the extreme north and south, whereas INAT concentrated all the occurrences in a more limited area, included in WEB and SAG. Both citizen science initiatives concentrated their records in areas of high human populations whereas SAG records had a more even distribution across regions. At 2020, WEB accounted for 55%, SAG 54%, and INAT 8% of the total area accumulated with H. axyridis, with only 16% of area shared among databases. WEB and INAT obtained most of their records in urban and industrial land cover types, while SAG records were more evenly represented in different land cover types. Our results confirm that combined methods, including citizen science initiatives, national surveillance system, and localized samplings, complement each other in providing knowledge to understand the patterns, processes, and consequences of this invasion.

Individual and population-scale carbon and nitrogen isotopic values of Procambarusclarkii in invaded freshwater ecosystems.

Freshwater ecosystems are amongst the most threatened habitats on Earth; nevertheless, they support about 9.5% of the known global biodiversity while covering less than 1% of the globe's surface. A number of anthropogenic pressures are impacting species diversity in inland waters and, amongst them, the spread of invasive alien species is considered one of the main drivers of biodiversity loss and homogenisation in freshwater habitats.Crayfish species are widely distributed freshwater invaders and, while alien species introductions occur mostly accidentally, alien crayfish are often released deliberately into new areas for commercial purposes. After their initial introduction, crayfish species can rapidly establish and reach high-density populations as a result of their adaptive functional traits, such as their generalist diet.The Louisiana crayfish Procambarusclarkii (Girard, 1852) is globally considered one of the worst invaders and its impact on recipient freshwater communities can vary from predation and competition with native species, to modification of food webs and habitat structure and introduction of pathogens. Native to the south United States and north Mexico, P.clarkii has been introduced in Europe, Asia and Africa, determining negative ecological and economic impacts in the majority of invaded habitats where it became dominant within the receiving benthic food webs. Due to its flexible feeding strategy, P.clarkii exerts adverse effects at different trophic levels, ultimately affecting the structure and dynamics of invaded food webs. It is, therefore, paramount to evaluate the ecological consequences of P.clarkii invasion and to quantify its impact in a spatially explicit context. In the past decades, the analysis of stable isotopes of carbon, nitrogen and other elements has become a popular methodology in food web ecology. Notably, stable isotope analysis has emerged as a primary tool for addressing applied issues in biodiversity conservation and management, such as the assessment of the trophic ecology of non-indigenous species in invaded habitats. Here, we built two geo-referenced datasets, resolved respectively at the population and individual scale, by collating information on δ13C and δ15N values of P.clarkii within invaded inland waters. The population-scale dataset consists of 160 carbon and nitrogen isotopic values of the Louisiana crayfish and its potential prey, including living and non-living primary producers and benthic invertebrates. The dataset resolved at individual scale consists of 1,168 isotopic records of P.clarkii. The isotopic values included within the two datasets were gathered from 10 countries located in Europe, Asia, Africa and North America, for a total of 41 studies published between 2005 and 2021. To the best of the authors' knowledge, this effort represents the first attempt to collate in standardised datasets the sparse isotopic information of P.clarkii available in literature. The datasets lend themselves to being used for providing a spatially explicit resolution of the trophic ecology of P.clarkii and to address a variety of ecological questions concerning its ecological impact on recipient aquatic food webs.