Search Results (35)

Introduction: The global ornamental fish trade is a rapidly expanding sector and a major pathway for the introduction of non-native species, particularly in freshwater ecosystems in developed countries. The introduction of non-native species can result in a range of ecological impacts, including predation, competition, hybridization, and disease transmission, often leading to ecosystem degradation and biotic homogenization. Therefore, it represents a clear ecological risk, especially serious in freshwater systems with a high endemism rate, such as the Iberian Peninsula. The occurrence of ornamental non-native species in the Iberian Peninsula has been common, yet little has been done to describe the overall ornamental fish trade as a first step to evaluate invasion risk. Objective: This study characterizes the import dynamics of ornamental freshwater fish in Portugal between 2020 and 2024 and evaluates its potential role as a pathway for species introductions. Methodology: Data were obtained from the Institute for Nature Conservation and Forests database, including information on species composition, quantities, sizes, prices, and countries of origin. A total of 431 records were analyzed, resulting in 27,689 validated entries of imported freshwater fish, which were taxonomically verified and filtered to retain only freshwater species. Results: A total of 666 species from 88 families were identified, with an average of 380 species imported annually, reflecting high taxonomic diversity. Import volumes increased from approximately 1.25 million individuals in 2020 to 1.75 million in 2024, while total import value nearly doubled from €300,000 to €600,000. Imports were predominantly from five Southeast Asian countries, particularly Indonesia and Vietnam, and largely supported by aquaculture production (88%). A stable core of highly traded species, including Carassius auratus, Poecilia reticulata, and Paracheirodon innesi, suggests a sustained and very high propagule pressure, while some species variability was observed on yearly basis, suggesting the importance of monitoring programs on actual imports. Conclusions: Overall, the ornamental fish trade represents a significant and growing pathway for biological invasions in Portugal. The combination of increasing trade volume, high species diversity, and persistent dominance of key taxa highlights the need for improved monitoring, regulatory frameworks, and public awareness to mitigate ecological risks. Full article

Invasive alien species (IAS) threaten coastal wetland ecosystems, and smooth cordgrass (Spartina alterniflora) is among the most damaging invaders along the coast of China. We compiled occurrence records from the invaded range (China) and native range (United States) and retained 358 and 291 spatially thinned occurrences after quality control and definition of coastal-accessible areas. We assembled climatic, topographic, land use, soil and anthropogenic predictors and fitted species distribution models using the biomod2 ensemble-modeling framework, complemented by an ecospat-based comparison of native and invaded niche spaces. The ensemble model (EM) showed high predictive accuracy (China: AUC = 0.98, TSS = 0.99; USA: AUC = 0.99, TSS = 0.94). Elevation (73.6%) and human influence (6.0%) were the strongest predictors, highlighting the role of intertidal geomorphology and human-mediated propagule pressure. Niche overlap between ranges was low (Schoener’s D = 0.13), and the invaded niche showed substantial unfilling (0.36), indicating additional environmental space at risk of colonization in China. The current suitable habitat forms a continuous coastal belt from the Bohai Rim through the Yellow Sea–East China Sea to the South China Sea. Projections under future climate change suggest predominantly stable suitable areas with localized expansions but potential contractions in some periods. Our results may support the early warning, surveillance prioritization, and adaptive management of S. alterniflora under climate change. Full article

Introduction: Freshwater ecosystems are global biodiversity hotspots, yet they remain highly vulnerable to biological invasions. Non-native freshwater fish species (NNFS) have established self-sustaining populations across nearly all biogeographic realms, reshaping regional ichthyofaunas and driving community-level impacts through predation, competition, hybridisation and ecosystem disruption. Critically, both foreign introductions and within-country translocations (extralimital species) contribute to this process, yet the latter remain more weakly regulated and consistently under-studied in invasion risk frameworks. Objective: We developed a stage-structured profiling framework to jointly evaluate foreign and extralimital NNFS in Greece and predict three sequential invasion outcomes, establishment, spread and integration, with the goal of identifying the ecological traits and pathway variables that best explain invasion success at each stage and informing management policy. Methodology: We compiled a dataset of 63 NNFS recorded in Greek freshwaters (36 foreign, 27 extralimital), characterised by eleven ecological, biogeographic and anthropogenic attributes. Logistic and multiple regression models and classification and regression trees (CART) were fitted independently for each invasion stage, with cross-validated predictor screening to limit multicollinearity and a taxonomy-based covariate to account for phylogenetic non-independence. Results: All 27 extralimital translocations established successfully, compared with only 11 of 36 foreign introductions, underscoring the disproportionate establishment success of within-country movements. Establishment probability was positively associated with high physiological tolerance and proximity to the nearest native source, and negatively associated with maximum adult size; propagule pressure provided only weak additional support. Spread across drainage basins was driven primarily by introduction effort and physiological tolerance. Integration increased with introduction effort, while the CART identified distance from the nearest native source as the primary partition of widespread, high-abundance outcomes, with trophic level further structuring outcomes among extralimital taxa. Conclusions: Our results indicate that management frameworks focused solely on foreign NNFS substantially underestimate invasion risk from within-country translocations. A compact set of predictors, biogeographic proximity, physiological tolerance and introduction effort, offers a practical, pathway-inclusive screening tool to guide prevention, surveillance and early detection in Mediterranean river networks, addressing a recognised European policy gap where extralimital movements remain more weakly regulated than foreign introductions. Full article

Introduction of species represents today one of the most important problems of nature conservation. Special attention is paid to alien vascular plants and vertebrates. In the Afrotropical Region (sub-Saharan Africa), however, there is a lack of comprehensive review of alien amphibians and reptiles. The presented paper constitutes an attempt to overview the status, distribution and threats posed by introduced herp species to sub-Saharan Africa since the second half of the 18th century. This review includes 21 amphibian (including 10 established) and 57 reptile (including 33 established) species introduced to sub-Saharan Africa. Most species introduced to sub-Saharan Africa which subsequently developed viable populations originated from the Malagasy (32%), Afrotropical (30%), and Oriental (27%) Regions. Most introductions were made in the last two decades, mostly as results of an increase in international trade and herp pet industry, especially in South Africa. Stowaway and pet trade are the most common pathways of introductions. Several factors determine the successful establishment of introduced alien herp species in sub-Saharan Africa, viz. behavioral and morphological traits, propagule pressure, climate and habitat overlap, and presence of potentially competing species. The impact of alien herps in sub-Saharan Africa on the local biodiversity is not well investigated. In comparison with other continents the number of introduced and established herp species in sub-Saharan Africa is relatively low. The Malagasy Region has the highest number of introduced herp species in sub-Saharan Africa. Full article

Railway corridors create persistent linear habitats embedded within intensively managed agricultural landscapes and can simultaneously support native biodiversity and facilitate the spread of undesirable taxa. We evaluated vegetation composition across five habitat types associated with railway line no. 250 (Havlíčkův Brod–Tišnov, Czech Republic): railway yard, railway embankment, railway land, field margin, and adjacent arable land. Vegetation was recorded using phytosociological relevés (10 m²) at four localities during three surveys in the 2021 growing season. In total, 83 plant taxa were identified, with pronounced differences among habitat types. Species richness and vegetation structure were highest in railway embankments, railway land, and field margins, whereas the railway yard and arable land exhibited lower diversity consistent with high disturbance intensity and substrate constraints. Canonical correspondence analysis distinguished habitat-affinity assemblages, indicating strong habitat filtering along the railway–agriculture gradient. Classification by origin and invasion status showed that non-native and invasive taxa were concentrated predominantly in railway embankments and adjacent habitats, suggesting elevated propagule pressure and potential spread into surrounding farmland. Colonization success (ICS) and colonization potential (ICP) indices indicated that railway-associated habitats can host taxa with high establishment capacity, contributing to successional stability within the corridor. These findings highlight railways as multifunctional elements of agricultural landscapes that require integrated vegetation management to balance biodiversity benefits with operational safety and invasive species risk. Full article

Neltuma juliflora (Sw.) Raf. (syn. = Prosopis juliflora (Sw.) DC.) is among the world’s most aggressive woody invaders, yet its ecological impacts remain poorly quantified in hyper-arid environments, where soils are calcareous and ecosystems recover slowly from disturbance. In this study, we tested two hypotheses: (1) the presence of N. juliflora changes native plant diversity, as well as soil and key physicochemical properties in hyper-arid Qatar, and (2) agricultural farms act as primary sources of N. juliflora invasion. Using a comparative observational design across 62 sites (45 invaded and 17 non-invaded), we applied a generalised additive model (GAM) and a generalised linear mixed model (GLMM) to quantify invasion drivers and the impact of invasion on perennial species diversity, respectively. Additionally, we used the Wilcoxon rank-sum test to compare the soil properties in the invaded and non-invaded sites. Our results indicate that N. juliflora is positively associated with farms, with the probability of occurrence declining by ca. 20% for each kilometre farther away from agricultural farms. This pattern suggests substantial propagule pressure from agricultural farms. Perennial species richness declined from 7.5 species at 0% N. juliflora cover to 4.8 species at full cover (36% reduction). Invaded sites were characterised by higher amounts of coarse sand (16%); reduced silt–clay fractions (5%); and elevated salinity indicators, including electrical conductivity (0.744 dS m⁻¹) and total dissolved solids (476 mg L⁻¹), while major N–P–K pools remained unchanged. These findings demonstrate measurable invasion-related changes in soil conditions and native perennial diversity in hyper-arid ecosystems and highlight the role of agricultural land use as a key driver of biological invasion. From a sustainability perspective, early detection, targeted control near agricultural and grazing zones, and integration of invasive species monitoring into land-use planning frameworks are essential to prevent further ecosystem degradation, protect biodiversity, and enhance the resilience of desert landscapes under increasing climate and land-use pressures. Full article

Ornamental horticulture represents one of the dominant pathways for the introduction of alien plant species and has played a central role in shaping current and future invasion dynamics. Many ornamental plants escape cultivation after long lag phases, driven by high propagule pressure, human-mediated selection of functional traits, and increasing climatic suitability. As a result, ornamental species contribute substantially to Europe’s invasion debt, with many future invasions already “locked in” under ongoing global change. In this review, we synthesize current knowledge on the invasive risk of ornamental plants in Europe, examining introduction pathways, biological traits promoting invasiveness, the role of climate change, and the ecological, economic, and social impacts associated with ornamental plant invasions. We highlight that beyond biodiversity loss, invasive ornamental plants pose underappreciated threats to agriculture and related activities, including increased management costs, weed problems in managed landscapes, and disruption of water management and irrigation infrastructure, particularly through invasive aquatic species. We further review tools for risk assessment and prevention, including weed risk assessment frameworks, green lists, horizon scanning, and climate-informed spatial forecasting, emphasizing the importance of proactive, pathway-based approaches. Where prevention fails, management of established invasive ornamentals relies on integrated strategies combining mechanical, chemical, and biological control, often generating large quantities of biomass and long-term economic costs. We discuss the emerging but still limited potential of invasive plant biomass valorization as a complementary management option, highlighting both opportunities and constraints. Finally, we discuss implications for horticultural practices, policy development, and future research, arguing that reconciling ornamental horticulture with biodiversity conservation and sustainable agriculture will require anticipatory governance, stakeholder engagement, and climate-aware decision-making. By aligning horticultural innovation with invasion risk awareness, it may be possible to reduce future invasions while maintaining the social and economic benefits of ornamental plant use in Europe. Full article

Background: Avicennia marina (Forsk.) Vierh., a widely distributed mangrove species, is known for its diverse secondary metabolites with potential pharmacological applications. Despite its dominance in the Arabian Gulf, where A. marina may have adapted to extreme environmental conditions with a distinct set of bioactive molecules, research in this region remains limited. Methods: This study investigates the phytochemical composition, antioxidant activity, and in vitro cytotoxicity of extracts from different plant parts, including roots, leaves, propagules, pericarps, and cotyledons, collected in the United Arab Emirates (UAE). Extracts were analyzed using ultra-pressure liquid chromatography coupled with high-resolution mass spectrometry (UPLC-HRMS). Antioxidant activity was assessed using DPPH and ABTS assays, while cytotoxicity was evaluated against human cancer and normal cell lines. Results: Analysis revealed 49 compounds, including iridoid glycosides, hydroxycinnamic acids, phenylethanoid glycosides, flavonoid glycosides, and triterpene saponins, several reported for the first time in A. marina and mangroves. The pericarp and root extracts exhibited the highest scavenging activity (DPPH: 187.14 ± 2.87 and 128.25 ± 1.12; ABTS: 217.16 ± 2.67 and 147.21 ± 2.42 μmol TE/g, respectively), correlating with phenylethanoid content. The root extract also displayed the highest cytotoxicity, with IC₅₀ values of 58.46, 81.98, and 108.10 μg/mL against MDA-MB-231, SW480, and E705, respectively. In silico analysis identified triterpene saponins as potential contributors. Conclusions: These findings highlight the root extract of A. marina as a promising source of bioactive compounds with potential antioxidant and anticancer applications, supporting further exploration for novel therapeutic candidates. Full article

Invasive species often defy theoretical expectations, successfully establishing and spreading despite reduced propagule pressure and limited genetic diversity. What genomic mechanisms underpin this paradox? How do adaptive processes and host–pathogen interactions shape invasion outcomes? And which genes drive resistance and modulate pathogen virulence? Here, we address these questions using a model of co-invasion: the Asian topmouth gudgeon (Pseudorasbora parva) and its fungal parasite the Rosette agent (Sphaerothecum destruens), a system with profound ecological and economic consequences. Here by (1) mapping the reads obtained by Illumina sequencing on a previously deposited P. parva genome from Germany, (2) identifying SNPs and (3) creating a consensus sequence, we generated the first whole genome of an invasive P. parva population in France and compared it to a German population to explore patterns of genetic diversity, local adaptation, and potential signatures of pathogen resistance. Despite historical bottlenecks, our results reveal unexpectedly high levels of genomic diversity between these invasive populations. We identify candidate loci linked to immune function and provide insights into the evolutionary dynamics of co-introduction. These findings offer a rare window into how invasive species maintain adaptability and how pathogens may co-evolve during range expansion. Beyond advancing our understanding of invasion biology, the genomic resources generated here pave the way for translational approaches, including the development of genome-editing strategies aimed at mitigating the impact of invasive species and their associated pathogens. This work marks a critical step toward unraveling the complex interplay between genetics, ecology, and evolution in biological invasions. Full article

The tree Ligustrum lucidum (W. T. Aiton, Oleaceae), native to East Asia (China), has become an aggressive invader of subtropical and temperate forests around the world. To understand how its local small-scale spread is controlled, we studied (48 plots of 4 m⁻²), in a subtropical forest of Uruguay, the distribution and survival of seedlings, saplings, and poles to assess the effects of dispersal from mother trees (distance), microsite type (forest stands defined by dominant species), and past control measures. The propagule pressure of L. lucidum, estimated through seedlings density, was between 100 and 1000 times higher than that of other species of the community and was concentrated around mother trees (<10 m of distance). Spatial variability of seedlings, saplings, and poles densities were explained by the interaction between distance to mother trees and forest stands. Significative lower densities were observed in the forest patches (stands) dominated by Jodina rhombifolia, and a field survival experiment confirmed lower survival of poles at Jodina stands, demonstrating that some resistance mechanism is operating there. We propose two biotic mechanisms of resistance: herbaceous competition and/or roots hemiparasitism by J. rhombifolia, reducing seedling and sapling survival. We concluded that a high propagule pressure, small-scale dispersal from mother trees, and patchy biotic resistance at Jodina stands control the local spread and domination process of the tree L. lucidum in the studied forest. Full article

Crambe sventenii Pett. ex Bramwell & Sunding and Pleudia herbanica (A.Santos & M.Fernández) M.Will, N.Schmalz & Class.-Bockh. are two single-island endemic species from Fuerteventura (Canary Islands), inhabiting the same areas and similar habitats. They are under the “Critically Endangered” category due to historical herbivore pressure, mainly goats, leading to habitat fragmentation and poor population recruitment. The main aim of our study was to provide insights into the conservation genetics and habitat suitability of these two species. For this purpose, we sampled all known populations on the island and developed two new sets of microsatellite markers. Moreover, to assist restoration plans, we performed species distribution models to determine the most suitable areas for reintroduction. While Crambe sventenii is highly fragmented, with low genetic diversity indices in some populations, Pleudia herbanica’s genetic structure is quite homogeneous, grouped in three main regions, with signs of inbreeding and an overall low genetic diversity. Both species could present moderate to high levels of autogamy. Our findings can provide guidance to local governments regarding conservation actions to be implemented in the field, like the identification of propagule sources and new suitable areas for restoration. Full article

Mangrove ecosystems are some of the most productive on our planet but have declined globally by 30–50%. Many species rely on mangrove habitats; thus, their conversion to aquaculture farms has led to noticeable losses in commodities such as wild fish stocks. This study aimed to assess the influence of aquaculture and restoration projects on the ecosystem’s ability to provide resources. We collected data on mangrove vegetation (i.e., biomass, richness, and abundance), soil nutrients (i.e., organic carbon, aluminium, and nitrogen), crab abundance, and fishing pressure at six sites. We set up 15 plots at each site and collected data between May and July 2023. Via generalised linear mixed models, we found that the abundance and richness of crabs was significantly higher in aquaculture plots than in non-aquaculture plots. Aquaculture plots had higher topsoil aluminium, higher topsoil and subsoil nitrogen, and lower topsoil carbon than non-aquaculture sites. Restored sites had less nitrogen in the topsoil than unmanaged sites. The biomass did not change between aquaculture, restored, and unmanaged plots. We found a negative correlation between crab abundance and richness and mangrove diameter at breast height (DBH), suggesting that the species of crabs present preferred areas with propagules for feeding (e.g., Grapsidae crabs). The content of nitrogen in the subsoil was positively correlated with mangrove richness, diversity, and height, suggesting the importance of nitrogen availability for mangrove growth. The content of aluminium in the subsoil was negatively correlated with the content of organic carbon in both the topsoil and subsoil, suggesting the detrimental effect of aluminium on the carbon cycle. Fishing practices were observed at all sites during the data collection period. Despite the lack of significant impact on most vegetation parameters and the limited differences between managed and unmanaged sites, key variables such as soil aluminium, carbon, and nitrogen contents and crab assemblages exhibited high variability, highlighting the complex interactions within mangrove ecosystems. Full article

Germination traits are components of invasion potential, and comparing seed traits in sympatric native and invasive species can offer insights into the invasion process. We characterized seed germination traits and how they influenced the success of Eragrostis mexicana, a native species, and Eragrostis tenuifolia, an exotic species (Poaceae) in Mexico, in the context of their potential for biological invasion. Seeds from both species were collected from four sites in a natural protected area in Mexico City, and the germination of seeds of different ages was conducted in experiments at different temperatures. E. tenuifolia exhibited higher germination percentages than the native E. mexicana across all treatments. Seed age had differential effects, with older seeds of the native E. mexicana germinating better, while E. tenuifolia performed better with younger seeds. Temperature positively impacted germination for both species, although E. mexicana was limited at lower temperatures. Exotic E. tenuifolia can germinate over a wider temperature range with earlier germination rates, and generate a seed bank lasting several years, which may contribute to naturalization. The importance of germination traits in the context of invasive species establishment underscores the potential role of seed banks in facilitating biological invasions. Full article

Biological invasions are one of the main threats to biodiversity, but they also offer insights on different ecological processes, as highlighted by the hypotheses posited to explain the phenomenon. We explore the relative importance of different hypotheses using biotic (native diversity) and abiotic factors (climate and landscape configuration) as proxies driving the spatial pattern of alien plant biodiversity in Greece. The strongest predictor of alien species richness is native species richness. Landscape heterogeneity boosts this relationship, but native and alien species prefer different conditions. Landscape composition and configuration explain more of the variance of alien diversity than of native diversity, with native diversity increasing at more naturally vegetated areas and alien diversity at agricultural lands. Climate is associated more strongly with native diversity than with alien diversity, with native diversity increasing in colder regions and alien diversity in warmer regions. The transportation network was associated with higher alien species richness but not with native species richness, highlighting the importance of propagule/colonization pressure. These differences might indicate that aliens occupy part of the niche space that is not preferred by the natives and thus allow us to speculate on the role of limiting similarity as a driving force. Full article

North American bean thrips, Caliothrips fasciatus, native to California U.S., has been detected inside the navels of navel oranges exported from California for more than 120 years. Despite this long history of accidental movement into new areas, this thrips has failed to establish populations outside of its native range. The cold accumulation hypothesis postulates that increasing levels of cold stress experienced by thrips overwintering inside navels is compounded when harvested fruit is shipped under cold storage conditions. Consequently, the fitness of surviving thrips is compromised, which greatly diminishes invasion potential. At the time this study was conducted, the effects of temperature on C. fasciatus fitness were unknown. To address this shortcoming, the effects of nine fluctuating temperatures that averaged 8, 10, 15, 20, 25, 30, 32, 35, and 37 °C over a 24 h period on the developmental and reproductive biology of C. fasciatus were evaluated. One linear and five nonlinear regression functions were fit to egg-to-adult development rate data for parent and offspring thrips to characterize thermal performance curves. Estimates of minimum, optimal, and maximum temperature thresholds for development were in the ranges of −4.37–6.52 °C (i.e., T_min), 31.19–32.52 °C (i.e., T_opt), and 35.07–37.98 °C (i.e., T_max), respectively. Degree day accumulation to complete development, estimated from linear regression, ranged 370.37–384.61. Average development times for eggs, first and second instar larvae, propupae, pupae, and adult longevity, and mean lifetime fecundity of females were significantly affected by temperature. These biological responses to temperature may provide insight into how this abiotic variable affects the invasion potential of C. fasciatus. Full article