Considering the high invasiveness of lodgepole pine (LP, Pinus contorta Dougl.) in parts of its introduced range, concerns about invasion risks in the Baltic region have been raised. In this regard, self-regeneration, dispersion distance, and factors affecting LP regeneration outside plantations were studied in Latvia, where the species is still considered as an alternative for forest regeneration. Among the 20 plantations investigated, 45% contained seedlings or saplings of LP. The density of LP within and in proximity to the plantation (up to 90 m) was similar, at 240 ± 78 and 234 ± 103 seedlings ha-1, respectively. The assessed LP plantations were still young (28 to 47 years), which might have contributed to lower pressure of propagules on the surrounding area, as the most distant seedling was found at 89 m. Site properties affecting LP regeneration included the absence of large canopy openings and bare soil, lack of competition, and, particularly, high browsing damage (24%) on seedlings over 30 cm. The regeneration densities and biotic limitations suggest that the invasion risk of LP in Latvia is currently low, nevertheless, monitoring of dispersal is still needed.
Invasive apple snails ( Pomacea spp.) have caused severe ecological and agricultural damage globally. Revealing their invasion history and genetic background is critical for effective management; however, traditional single-locus markers often provide insufficient resolution for deciphering complex dispersal routes or cryptic maternal lineage structures. Here, we conducted a comprehensive phylogeographic study by analyzing 428 complete mitochondrial genomes from China and Southeast Asia and 3,132 global COI sequences of three apple snail species, including P. canaliculata , P. maculata , and P. occulta . Mitogenomic analysis revealed a complex invasion history of P. canaliculata , and high genetic diversity was maintained in this species largely due to multiple independent introductions of three genetically divergent maternal lineages. We further resolved widespread COI haplotypes into finer geographic structure, highlighting the complexity of regional invasion and dispersal of P. canaliculata . In contrast, P. maculata in mainland China exhibited a single mitogenomic haplotype, consistent with a more restricted maternal pattern in the current dataset. Furthermore, our analysis identified that the recent outbreak of P. canaliculata in Kenya likely represents a secondary invasion event originating from Asian populations, highlighting a bridgehead effect. COI -based neutrality tests and mismatch analyses indicated that some invasive lineages experienced rapid recent population expansion, contrasting with the long-term stability of native populations. These findings provide essential genetic evidence and high-resolution resources for the global monitoring and biosecurity management of invasive apple snails.
Multiple species of land planarians have become established outside their natural ranges. Some are considered invasive because of their rapid spread and adverse effects on ecosystems. Once established, land planarians are difficult to manage. Therefore, it is crucial to document their presence and spread and assess their risk. This study provides an annotated checklist and distribution maps of all non-native land planarians recorded in Belgium, as well as a climate-matching analysis and a Harmonia + risk assessment for each species. A climate-matching analysis and a risk assessment were also conducted for two species that do not occur in Belgium but are included in the European Union’s list of invasive alien species of Union Concern: Platydemus manokwari and Arthurdendyus triangulatus . Thus far, nine non-native land planarian species have been recorded in Belgium: Anisorhynchodemus cf. signata, Bipalium kewense , Caenoplana coerulea , C. variegata , Diversibipalium multilineatum , Dolichoplana striata , Marionfyfea adventor , Obama nungara , and Parakontikia ventrolineata . Climate-matching percentages were highest for A. triangulatus , M. adventor , C. variegata , and O. nungara . Obama nungara is the only species that received a very high environmental risk score. Diversibipalium multilineatum and P. manokwari both received high environmental risk scores. The overall risk score was medium for O. nungara and D. multilineatum and low for all other species. The information presented in this review may provide a basis for developing suitable detection and monitoring methods and rapid-response strategies for high-risk non-native land planarians.
The European catfish Silurus glanis L. is a large, adaptable predator whose range continues to expand rapidly in Europe, posing potential environmental, ecological and socio-economic impacts on freshwater ecosystems. Its success results from a combination of species-specific traits and extrinsic abiotic and anthropogenic drivers, which together enhance its ecological adaptability and competitive advantage. While some studies report substantial impacts on fish communities, others find minimal effects, likely due to differences in timing of data collection, lack of baseline data, control sites and assessments of biotic and abiotic interactions. In this review, we: (i) explore the main factors contributing to the invasion success of S. glanis , including both species-specific traits (e.g. trophic plasticity, reproductive strategies, environmental tolerance) and extrinsic drivers, such as propagule pressure, human-assisted dispersal and habitat alterations; (ii) assess its ecological effects across freshwater ecosystems, based on available studies; and (iii) review the methods commonly used for detecting S. glanis , highlighting their pros and cons for species detection. In each section, we highlight key knowledge gaps, such as the lack of experimental studies, limited understanding of long-term impacts on native species and insufficient data on context-dependent effects. These gaps emphasise the urgent need for coordinated research efforts to improve impact assessment and guide effective management strategies.
The negative impact of alien species is recognised as a major threat to biodiversity. An impact indicator, a measurable proxy of the status of alien species impacts over space and time, is essential for informing biological invasion policies and management strategies. We introduce an open-source workflow for computing impact indicators of alien species, combining occurrence data from the Global Biodiversity Information Facility (GBIF) with assessments of Environmental Impact Classification for Alien Taxa (EICAT). To implement the workflow, we developed an R package, impIndicator, which allows users to compute and visualise impact indicators for individual species and sites, as well as regional impact indicators. This tool can support ecological research and management by providing standardised insights into where alien species pose the greatest threats and whether current interventions are effectively reducing them. Such information is directly relevant to policy frameworks, including Target 6 of the Convention on Biological Diversity’s Kunming–Montreal Global Biodiversity Framework and the Sustainable Development Goals. We demonstrate the workflow using Acacia species in the Iberian Peninsula, South Africa and California, showcasing the spatiotemporal dynamics of their impacts and highlighting sites with higher impact risk. The resulting impact indicators were sensitive to variation in sampling effort and the completeness of the underlying occurrence data, highlighting the importance of well-sampled and systematically curated biodiversity datasets for robust impact assessment.
Freshwater ecosystems and fish fauna are experiencing severe anthropogenic pressures and declines worldwide, with non-native species as a major contributing factor. Decades of stocking with non-native species, dam construction, urbanisation and water extraction may have had major negative effects on native (endemic) fish fauna in Dalmatian rivers, a biodiversity hotspot in the Western Balkans. Therefore, the aim of the study was to investigate potential spatial and temporal changes in the fish community of the Krka River in Croatia, while exploring functional traits and taxonomic diversity to assess the potential impact of non-native species on the ecosystem. Data spanning a 20-year period was assessed to understand the composition and distribution of the fish communities. These analyses, in combination with ordination approaches, indicated a clear spatial and temporal change in the fish community of the Krka River, with native species being more abundant in the past (2004–2008) and non-native taxa becoming more dominant recently (2020–2024). This change was obvious in the investigated guilds, specifically in status (increase in non-native taxa), reproduction (dominance of macrophyte-related species) and feeding habits (prevalence of omnivores/invertivores). Here, we demonstrate that 20 years is sufficient for a shift in the structure and distribution of freshwater fish communities in a karst river in the Mediterranean region.
Invasion of native Mediterranean vegetation by fire-adapted plant species may create a feedback loop where fire facilitates the invasion process which, in turn, increases fire hazard due to fuel accumulation. This relationship may pose challenges for ecosystem management since fuel reduction and invasion control are often constrained by restrictions in the use of prescribed fire and other disturbance-based control approaches. This is the case for Hakea decurrens, an Australian woody species, which regenerates after fire through seedling recruitment. Here, we investigated the regeneration processes of H. decurrens using different treatment alternatives aimed at finding better management solutions. The objectives of this study were to examine: 1) the effects of different combinations of Slash and Burn treatments on seedling establishment of H. decurrens; 2) the plant attributes that favour resprouting after Slash; and 3) the effects of fire-related heat exposure on follicle dehiscence and seed viability. Four treatment plots were established on five stands of H. decurrens: Burn, Slash, Slash & Burn, and Control. Treatments were applied once per plot, with Slash and Slash & Burn treatments introduced at different times across sites, and plots were monitored for 1080 days to assess seedling density and resprouting capacity. Additionally, fruits (follicles) were exposed to different heat residence times and seed viability tested to evaluate responses to fire. Slash and Slash & Burn treatments were more effective in reducing H. decurrens seedling densities than the Burn treatment alone. Resprouting following slashing decreased with increasing trunk basal diameter and was virtually absent above ~3 cm. When follicles were exposed to experimental fire for 120 s or more, seed viability decreased, approaching zero at 180 s. The results of this study indicate that Slash and Slash & Burn techniques are effective for initial control of H. decurrens. However, control of this species requires several interventions to deal with new seedlings, and invaded areas must be monitored and integrated into recovery programmes, especially where fires are frequent.
Erthesina fullo (Thunberg, 1783) (Hemiptera, Pentatomidae) is an emerging invasive pest outside its native Asian range, yet little is known about its egg parasitoids. Egg parasitoid assemblages were surveyed from field-collected egg masses of E. fullo in its native range in China and invaded range in Albania, and from egg masses of Apodiphus amygdali (Germar, 1817), a related European pentatomid sharing a similar ecological niche in Greece. Field-collected egg masses were examined for parasitism, and parasitoids were identified using morphology and DNA barcoding. Parasitoid body size was also compared among host species. In China, 53% of E. fullo eggs were parasitized, with Trissolcus japonicus (Ashmead, 1904) (Hymenoptera, Scelionidae) and Anastatus japonicus Ashmead, 1904 (Hymenoptera, Eupelmidae) recovered, providing the first field evidence of these species from this host. Trissolcus japonicus emerging from E. fullo was larger than conspecifics emerging from Halyomorpha halys (Stål, 1855) (Hemiptera, Pentatomidae). In Albania, parasitism was lower (13.1% of eggs), and only native European species, Trissolcus saakowi (Mayr, 1903) and Anastatus bifasciatus (Geoffroy, 1785) were recovered, representing the first records of parasitoids attacking E. fullo eggs in its invaded range. Trissolcus saakowi also emerged from A. amygdali in Greece, supporting the hypothesis that ecological similarity between native and invasive hosts may facilitate adoption of non-native hosts by native parasitoids. These results show that both the adventive egg parasitoid T. japonicus and the native egg parasitoids, A. bifasciatus and T. saakowi, may contribute to the biological control of E. fullo in Europe, although their current impact appears limited.
Impacts of non-native fish species (NNF) on ecosystems and human communities can be substantial and in principle be either detrimental or beneficial for native species or people. Studies on NNF vary geographically, with little research comparing NNF impacts in wealthier countries to those in other parts of the world. We assessed impacts of the 20 most widely distributed fish species that are non-native to India and compared their documented impacts in India with those elsewhere in the world. We considered detrimental and beneficial environmental and socio-economic impacts, applying all four Impact Classification for Alien Taxa (ICAT) tools to assess impacts of non-native species: the IUCN Environmental Impact Classification for Alien Taxa (EICAT), EICAT+, Socio-Economic Impact Classification for Alien Taxa (SEICAT), and SEICAT+. Five NNF were classified as Data Deficient due to a lack of relevant impact records. Among the 442 relevant impact records for the 15 remaining NNF at the global scale, detrimental environmental impacts dominated (384), with fewer records pertaining to beneficial environmental (34), detrimental socio-economic (14) and beneficial socio-economic (10) impacts. A predominance of detrimental environmental impacts (35) over all other impact types (10) was also detected for India. Our results show that NNF can cause reductions in the population size of native species, particularly in macrophytes. Severity of detrimental environmental impacts (at the individual or population level of native taxa) did neither vary with transfer type (inter- or intra-realm), nor impact location (India or rest of the world), nor detection type (observed, field experiment, in-situ mesocosm, exclosure/enclosure experiment, or intervention). Based on our findings, we suggest prioritizing macrophytes for threat evaluation—while emphasizing that other taxa are not free from risk from NNF—and conducting targeted studies in India to detect impacts of NNF and fill critical impact data gaps.
Understanding trophic interactions among invasive species is essential for predicting invasion dynamics and informing management. However, direct trophic interactions among co-occurring invaders have rarely been quantified using functional response approaches, particularly in freshwater ecosystems. Here, using semi-natural enclosure experiments, we quantified the functional responses of two widespread aquatic invaders in the Lower Ebro River (NE Spain): the apple snail (Pomacea maculata) and the blue crab (Callinectes sapidus). Feeding rates on alternative resources were used to estimate per capita effects and extrapolate potential population-level impacts. Apple snails exhibited Type II (hyperbolic) functional responses when feeding on the exotic macrophyte (Ceratophyllum demersum) and Type III (sigmoidal) on rice seedlings (Oryza sativa). While consumption rates standardized by prey biomass were approximately five times higher on the macrophyte, apple snail increased more weight when fed with rice, evidencing nutritional differences among resources. Blue crabs showed a Type II response when preying on apple snails and a Type III on the invasive Asian clam (Corbicula fluminea). Blue crabs generally lost weight in both experiments, suggesting potential nutritional limitations under enclosed conditions. By integrating experimental functional responses with field-based abundance data, this study provides an empirical assessment of trophic impacts in a Mediterranean freshwater ecosystem. Our findings highlight how invasive resources can support invasive consumers forming an all-invasive trophic chain, and underscore the need for management strategies that consider food-web interactions rather than focusing on single species in isolation.
Invasive shrubs can modify ecosystem structure and functioning in ways that depend on their ontogenetic stage, yet this dimension of invasion impacts is rarely examined. We investigated how the ageing of Rosa rugosa thickets influences vegetation, soil properties and microbial functioning in grey dunes of the Baltic coast. By sampling the centres and edges of shrub patches, as well as adjacent resident vegetation and sparsely vegetated bare sand, we assessed how invasion effects vary along a demographic gradient. Ageing thickets formed partially open centres (due to shoot senescence and dieback), creating microsites favourable to late-successional and shrub-associated species. At the same time, the concurrent development of a dense root-litter mat inhibited the recovery of specialist grey dune flora, thereby stabilising a successional shift towards more widespread, mesic-tolerant assemblages. Changes in soil physicochemical properties were moderate and largely associated with organic-layer build-up and sea-spray interception, whereas microbial communities showed rapid and pronounced functional responses, particularly in respiration and enzyme activity. These results demonstrate that R. rugosa acts as an ecosystem transformer whose impacts intensify and change through ontogeny. Importantly, natural senescence of thickets does not reverse invasion effects, but reinforces successional advancement, highlighting the need for active management to protect grey dune biodiversity.
Biological invasions represent a major threat to global biodiversity, yet alien invertebrates remain among the most understudied taxonomic groups despite their severe ecological and socio-economic impacts. At European level, the EU Regulation 1143/2014 emphasizes the need for coordinated monitoring and management of invasive alien species, but implementation is hindered by the scarcity and fragmentation of information, particularly in Central and Eastern Europe. To tackle these shortcomings, we compiled a comprehensive, FAIR-compliant dataset detailing alien invertebrate occurrences in Romania, using data from scientific literature (1865–2023), field surveys (2020–2022), and citizen science observations (up to 2023). This dataset encompasses 23415 records of 297 alien species, of which 212 are terrestrial (71.38%), 27 are freshwater (9.09%), and 58 are marine species (19.53%). Our results show that 170 species (57%) were recorded by only one source, whether scientific literature, fieldwork, or citizen science, while the remaining 127 species (43%) were documented by two or more sources combined. Scientific literature yielded the highest number of species (241), but 119 of these were not confirmed by our recent fieldwork or citizen-science observations. Citizen scientists reported 60 alien species, eight of which were recorded solely through this approach. The dataset also emphasizes spatial clustering around major urban areas in Romania and waterways, reflecting introduction pathways and sampling bias. In terms of management priorities, three species of EU concern, i.e., Faxonius limosus (Rafinesque, 1817), Procambarus virginalis Lyko, 2017, and Eriocheir sinensis (H. Milne-Edwards, 1853), exhibit sparse occurrence records despite their invasive potential. By mobilizing existing data into standardized and openly accessible formats, we promote evidence-based implementation of policies at national and international levels. Moving forward, comprehensive management of biological invasions requires enhanced coordination among researchers, citizen scientists, and policymakers, supported by interoperable information systems that facilitate rapid data flows.
Invasive non-native fish species are key drivers of biodiversity decline and functional homogenization in freshwater ecosystems. As a typical subtropical coastal river, the Jiulong River Basin faces a high risk of non-native fish invasions, with tilapia species dominating non-native fish biomass. However, quantitative understanding of the nutritional interactions between tilapia species and native fishes remains limited. This study used carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope analyses to assess the trophic structure, ecological niche width, and niche overlap of fish communities in the Jiulong River Basin, China. The results showed that fish δ 13 C and δ 15 N values ranged from −27.27‰ to −14.88‰ and 7.54‰ to 14.15‰, respectively, with trophic levels ranging from 2.33 to 4.27. Non-native fish species contributed nearly 50% of the total biomass, with tilapia species accounting for 39.16%. The average isotopic niche width of tilapia species (SEAc = 3.06‰ 2 ± 0.79) was significantly larger than that of native species (SEAc = 1.30‰ 2 ± 1.54). Moreover, the average niche overlap between tilapia species and native fishes was 50.78%, reaching 95%, 81%, and 66% for Pseudogobio vaillanti (Sauvage, 1878), Acrossocheilus fasciatus (Steindachner, 1892), and Gnathopogon argentatus (Sauvage & Dabry de Thiersant, 1874), respectively. The results indicate that non-native fishes, especially tilapia species, occupy broader ecological niches and exhibit substantial trophic overlap with native fishes, potentially affecting native fish populations. These findings provide a scientific reference for invasion risk assessment and management in subtropical river ecosystems.
The marbled crayfish (Procambarus virginalis) is an invasive, parthenogenetically reproducing species that has spread to freshwater ecosystems in more than 24 countries across North America, Europe, Africa, and the Middle East. To date, the trophic ecology of the marbled crayfish has been studied only in European lentic and lotic perennial ecosystems. This study aimed to shed light on the trophic ecology of the marbled crayfish in ephemeral streams of semi-arid environments in the Middle East. Three distinct habitats were compared using δ13C and δ15N stable isotope analysis to evaluate spatial variation in trophic position and resource use. A diet regime experiment was also conducted to test the impact of herbivorous and omnivorous diets on crayfish survival. In agreement with studies elsewhere, the analysis confirmed that P. virginalis functions as a flexible omnivore, occupying an intermediate trophic level (trophic position: 2.3–2.9), with the highest values observed during summer. The diet regime experiment indicated that juveniles can survive on various diets, with only small differences in survival rates among the three diets tested. The highest survival rate was observed under the poor plant-based diet. Adults and sub-adults also showed high survival rates under all tested diets, as well as some extent of cannibalism, which was amplified when they were fed purely plant-based diets. Cannibalism was primarily directed at small-sized juveniles (0–2 months old). In contrast, cannibalism among adults and sub-adults was very limited, even when they were reared at high densities.
Plastic pollution and biological invasions are two of the most pervasive and persistent drivers of ecological change. Although both have been widely studied in isolation, their potential interactions remain poorly understood. This review synthesises 146 peer-reviewed scientific articles published up to December 2024, providing the first global assessment of research at the intersection between plastic pollution and biological invasions. We found that the literature is taxonomically narrow, geographically skewed and methodologically fragmented. Research focuses on aquatic invertebrates, especially Mollusca and Arthropoda and is largely restricted to microplastics, with limited attention to mesoplastics, nanoplastics or terrestrial systems. Most studies use standardised ecotoxicological assays under laboratory or field conditions, leaving broader ecological processes, such as context-dependent interactions at the population, community and ecosystem levels, habitat modification by non-native species interacting with plastic debris and plastic-driven disruptions to ecosystem functioning and services, largely underexplored. Despite these limitations, we identified three recurrent pathways through which plastics and biological invasions interact: (1) non-native species dispersal and colonisation via plastic debris; (2) altered biotic interactions and (3) the experimental use of non-native species to assess plastic toxicity, with a focus on species-specific physiological responses. These interactions may influence bioaccumulation dynamics, contaminant transfer across trophic levels and compromise the resilience of invaded ecosystems. Our findings highlight key research gaps that include the limited integration of ecological responses in natural ecosystems, the under-representation of many taxonomic groups and the lack of comparative analyses exploring how non-native species may act as vectors for plastic transport and bioaccumulation. This situation implies the need for more mechanistic, context-sensitive and cross-disciplinary approaches. We also emphasise the urgent need to incorporate plastic pollution into non-native risk assessments and management frameworks. Strengthening methodological standardisation and public engagement, for instance through citizen science, will be critical for addressing the combined impacts of these two global stressors and mitigating their impacts.
Human introductions of plant species often lead to secondary invasions by non-native insects or range expansions of native ones. For instance, native insects may undergo extralimital spread when they adopt non-native plants that are closely related to their native host plants. Leptocoris soapberry bugs feeding on plants in the soapberry family (Sapindaceae) provide prime examples of such host shifts. In Australia and South Africa, the introduction of non-native sapindaceous plants, as well as human-mediated changes in the distributions of native ones, has the potential to impact the ecology and evolutionary dynamics of native soapberry bugs. Observations indicated that, in both countries, the ranges of some native Leptocoris species have expanded substantially due to the human-mediated movement and introduction of native and non-native sapindaceous species. In Australia, the native L. rufomarginatus has established in the Sydney region, where native Alectryon species have been introduced and naturalised well outside their historical ranges, i.e., extralimital host plant species, and the introduced non-native L. vicinus was found to be localised at its initial introduction site in Darwin on the non-native Schleichera oleosa. Species distribution models showed that vast areas in Australia currently have a suitable climate for both the native and non-native host plants of soapberry bugs. This suggests that range expansions by these host plants and insects are likely to continue. In South Africa, the native L. mutilatus now occurs ~1,000 km beyond its previously described range, feeding on the invasive balloon vine Cardiospermum grandiflorum and the non-native Australian tree A. connatus. Evidence is provided for differentiation in the proboscis length of L. mutilatus insects feeding on different non-native, invasive, and native host plants. In Australia, the native L. tagalicus was also successfully hybridised and backcrossed with the non-native L. vicinus, providing the first report of interspecific hybridisation for soapberry bugs under laboratory conditions. The shared evolutionary history between soapberry bugs and sapindaceous host plants suggests that further changes in these insects’ distributions and adaptive responses to novel host plants are likely to occur. Taken together, these results demonstrate how human-mediated plant dispersal affect the ecology, distribution, and evolution of native insects.
Invasive populations are managed most effectively when surveillance aligns with periods and places of maximal activity. Understanding the conditions influencing breeding of invasive species may help provide information for studies of population dynamics and range expansion. Despite their continued successful advances, the patterns and drivers of invasive cane toad (Rhinella marina) calling activity, as a signal of potential breeding activities, remain poorly resolved at broad scales in Australia. Using continent-wide passive acoustic recording data paired with a machine-learning acoustic classifier, we describe patterns in cane toad choruses across most of their current range in Australia, spanning three States and climate zones (~ 15° latitude and 27° longitude). A total of 163,701 minutes of cane toad calls from 33,799 nights of recordings showed that they chorused nearly year-round, with seasonal peaks. Cane-toad calling probability and intensity increased on dark, calm, humid nights and near lentic systems or temporary water, with low- to medium- canopy cover and decreased with increasing wind and moonlight. Social cues appeared important: prior-week calling activity strongly elevated both probability and intensity of calling. Interestingly, temperature effects were context-dependent, without a prior chorus, calling probability and intensity peaked at moderate temperatures; following chorusing, both metrics remained high across a broader thermal range. However, variable importance differed amongst climate zones: atmospheric and lunar factors were more influential for initiating choruses in subtropical and semi-arid sites, whereas habitat and hydrology contributed more to sustaining choruses in the Tropics. Together, these results reveal a detailed picture of cane toad calling ecology in Australia, identifying when, where and under what conditions chorusing is favoured. More broadly, this study demonstrates the value of ecoacoustics for investigating vocal invasive species at large spatial scales and provides a useful basis for future monitoring and modelling. Graphical abstract
Invasion-driven ecological transitions remain underrepresented in fine-scale analyses, despite their central role in reshaping native vegetation. This study investigated how the invasive species Asclepias syriaca alters community structure at the boundaries of invaded and non-invaded sandy grasslands in Central Hungary. Using high-resolution transect sampling and quantitative boundary detection methods (Moving split window analysis with Squared Euclidean distance and Differential Renkonen index), compositional discontinuities were assessed across six transects representing spatial replicates of invasion front zones within a shared invasion context. The results reveal that significant vegetation boundaries – termed “novel ecotones” – frequently precede or lag behind the visible shoot front of A. syriaca , indicating complex, non-linear invasion dynamics. These boundaries vary in sharpness, width, and spatial offset, suggesting that A. syriaca impacts community structure beyond its current spatial distribution. Contrary to expectations, species richness remained relatively stable, with shifts primarily affecting species dominance patterns rather than outright loss. The identification of ecotonal dissimilarity maxima demonstrates that spatial boundary metrics can help reveal invasion-related spatial patterns and can inform conservation and management strategies, particularly in identifying ecologically sensitive transitional zones. The approach appears more suitable for detailed ecological assessment and management planning than for rapid early detection. In particular, it may help identify transition zones where early intervention could be more effective. This study contributes to the integration of invasion ecology and boundary theory, emphasizing the spatial dimension of biotic restructuring by invasive species.
Lists of alien taxa facilitate the link between evidence and action and are thus essential for integrated governance. However, the recent IPBES IAS Assessment identified significant gaps in the completeness and availability of lists of alien taxa in the Global South. This article, also available in French, Portuguese and Spanish, introduces three joint special issues based on data collected from over 40 countries – 11 articles in African Biodiversity & Conservation addressing issues in Africa, five articles in Bioinvasiones addressing issues in Latin America and the Caribbean, and 12 articles in NeoBiota addressing issues of broader interest or from other regions. The articles: describe lists of alien taxa from different groups, environments and regions, (including countries, islands, and protected areas); compare lists from different countries; present workflows and protocols to address specific issues; and discuss experiences and lessons in the process of creating lists. The importance of applying and adapting approaches and terminologies to local contexts and languages rather than imposing them externally is discussed. However, it is also important that workflows and translation tables are available to ensure data are more accessible and interoperable, e.g. by explicitly linking to relevant taxonomic backbones, using Darwin Core terms, and contributing to the Global Register of Introduced and Invasive Species. Achieving these two aims will help lists be useful to local end-users and facilitate international collaboration, especially South–South initiatives.
Hydrological droughts driven by climate change threaten freshwater biodiversity, including relatively immobile bivalve fauna, unable to escape from air-exposed areas. Furthermore, they may exacerbate biological invasions by more resistant alien species. We measured survival and behavioural responses (migration following receding water line and burrowing) of the vulnerable native fingernail clam Sphaerium rivicola and the invasive Asian clam (Corbicula complex) to water level reduction and sandy substratum drying in a laboratory setting, to assess their susceptibility to a hydrological drought. Corbicula exhibited higher drought resistance with all clams surviving 15 days of air exposure, whereas S. rivicola reached LT50 (time at which 50% mortality occurred) in 5 days and LT90 (time at 90% mortality) in 8 days. During water level reduction, S. rivicola migrated by crawling downwards to wetter areas and reduced their burrowing depth, whereas Corbicula clams remained in place, burrowing deeper into the sediments. We demonstrate that the invasive Corbicula clams are superior to S. rivicola in surviving air exposure, and their burrowing confers an advantage in drought-prone habitats. In the context of climate change, increased drought frequency and duration may facilitate Corbicula’s dominance and replacement of less drought-resilient native bivalves, such as S. rivicola.
