Biological invasions lead to substantial changes in global biodiversity. Non-native species invade local ecosystems, interacting also with already established invaders. The presence of invasive species in ecosystem may facilitate secondary invasions by positive interactions. Alternatively, the success of invasion may be diminished by negative relationships among newly and previously introduced/established non-native species. However, few studies have determined joint effect of co-invasive competitors and predators on previous invaders. Our study aimed to estimate potential synergistic effects of the fish predator, Babka gymnotrachelus, and stronger interspecific competitor, Dikerogammarus villosus, on population dynamics of the prior invader, D. haemobaphes, all of Ponto-Caspian origin and invading many major European river basins. We hypothesized that abundance and distribution of prior invader would be negatively affected by presence of D. villosus and fish, either alone or simultaneously. Using mesocosm and laboratory experiments, we showed that the secondary co-invaders affected distribution and abundance of D. haemobaphes, depending on ontogenetic stage of the latter. Abundance of juvenile D. haemobaphes was reduced in presence of D. villosus, while presence of predator had no effect. Reversely, adult D. haemobaphes avoided the predators, but not competitors. In the simultaneous presence of both co-invaders, reactions of juvenile D. haemobaphes have reinforced: they were no longer able to hide against D. villosus and suffered greater abundance decline, pointing to synergistic negative effect of the competitor and predator. We provide experimental evidence demonstrating how negative interactions among invasive species may shape community structure. Moreover, as nowadays dispersal of species is driven by climate change, our results may be extrapolated to native communities, undergoing composition changes due to phenomena other than biological invasions.

Freshwater amphipods often include highly divergent molecular lineages with limited morphological variation, resulting in many reported cryptic species. However, most of these cases rely solely on mitochondrial markers, lacking nuclear and morphological characters. This study integrates multilocus phylogenetics and morphological examination to describe three new species in the Gammarus balcanicus complex from Romania. Gammarus balcanicus consists of narrowly endemic lineages spanning south-eastern Europe to Central Asia, many of which remain undescribed due to morphological stasis. The newly described species, Gammarus carausui sp. nov., G. dobrogicus sp. nov., and G. pinkfloydorum sp. nov., show significant divergence at mitochondrial and nuclear levels, along with consistent, yet subtle morphological differences compared to each other and to topotypical G. balcanicus from Montenegro. These species diverged in the Late Miocene, pre-dating Quaternary glaciations. Despite extensive sampling, two are known only from their type localities in the Carpathians, while G. dobrogicus is endemic to the Dobrogea plateau. Considering global threats to freshwater habitats, these species may already be endangered. This work highlights the role of molecular tools in resolving cryptic species' taxonomy and highlights the Carpathians as a crucial refugial region for relict pre-Quaternary fauna.

The groundwater amphipod genus Niphargus is highly diverse in southern Europe but has few representatives towards the northern limits of its range, where repeated Pleistocene glaciations have shaped its distribution. Two competing hypotheses have been proposed for northern Germany: survival north of the ice sheet during glacial periods versus post-glacial colonisation from southern refugia. To test these alternatives, we surveyed 58 sites in formerly glaciated northern Germany and analysed mitochondrial COI sequences from 23 collected specimens, supplemented with 123 sequences from previous studies. All specimens were assigned to Niphargus aquilex sensu stricto. Genetic diversity was extremely low in the northernmost group from formerly glaciated northern Germany, and its haplotypes were either unique or shared with nearby unglaciated groups. Analysis of Molecular Variance and pairwise Fst values indicated strong genetic structuring among geographic groups, whereas Mantel test showed no correlation between genetic and geographic distance. These results reject the hypothesis that the species survived north of the Pleistocene glaciation limit and instead support post-glacial colonisation from a very limited subset of southern mitochondrial lineages. Dispersal may have been facilitated by deep Pleistocene tunnel systems, as other dispersal pathways are less supported by the current data. Colonisation of northern Germany by N. aquilex appears to represent a rare, chance event within the genus. Understanding such restricted dispersal processes is essential for predicting responses of groundwater fauna to future environmental change.

The Biodiversity Genomics Europe (BGE) Project has the overarching aim of accelerating the use of genomic science to enhance understanding of biodiversity, monitor biodiversity change, and guide interventions to address its decline. The BGE Project comprises activities focused on DNA Barcoding (Barcoding Stream) and Reference Genome Generation (Genomes Stream) for eukaryotic species across Europe, bringing together two European networks: the International Barcode of Life in Europe (iBOL Europe) and the European Reference Genome Atlas (ERGA). This publication is an abridged version of the successful grant proposal developed jointly by iBOL Europe and ERGA in response to the Horizon Europe call HORIZON-CL6-2021-BIODIV-01-01. Two key strands of genomic science form the basis of this proposal: DNA barcoding - sequencing short, standardised genomic regions to tell the world’s species apart, transforming the speed of completion of the inventory of life on Earth and providing the foundations of a global bio-surveillance system for biodiversity; and genome sequencing - generating high-quality complete reference genomes for all species on Earth, transforming understanding of biodiversity at the genetic level, and delivering fundamental knowledge of how biological systems function and how species respond and adapt to environmental change. The BGE Project objectives are focused on (i) Capacity: To establish functioning biodiversity genomics networks at the European level to connect and grow community capacity to use genomic tools to tackle the biodiversity crisis; (ii) Production: To establish and implement large-scale biodiversity genomic data generation pipelines for Europe to accelerate the production and accessibility of genomic data for biodiversity characterisation, conservation, and biomonitoring; and (iii) Application: To apply genomic tools to enhance understanding of pan-European biodiversity and biodiversity declines to improve the efficacy of management interventions and biomonitoring programmes.

The River Habitat Survey (RHS) is a method used to assess the condition of river channels and valleys by considering hydromorphological factors. It evaluates the degree of naturalness or anthropogenic alterations based on physical and landscape data. The study hypothesized that the quality of river habitats, as demonstrated by the RHS, should correlate with the composition of aquatic bugs (Heteroptera) fauna. The research was conducted in the River Krąpiel, a small lowland river in north-western Poland, across 6 sites and 43 sub-sites. Our analyses suggest that the RHS method can predict the composition and quality of aquatic bug fauna. Other indicators, such as the Habitat Quality Assessment (HQA) and the Riverine Habitat Quality Index (RHQI), are associated with different habitat types. Depending on the geographic location and river type, these indicators may reflect differences between habitats associated with the mainstream river and mineral substrates versus those covered by vegetation with relatively slow water flow. Linking the size and character of the river, RHS may be a good method for estimating the water bug fauna.

ABSTRACT DNA barcoding is a highly effective tool for species identification, complementing taxonomic and phylogenetic studies while also playing a key role in biomonitoring and uncovering cryptic diversity. Techniques such as DNA barcoding, metabarcoding and environmental DNA (eDNA) analysis are widely applied in biodiversity conservation, tracking invasive species and studying trophic interactions. To carry out this type of research effectively, a robust DNA barcode library is essential, built upon high‐quality genetic sequences and accurate taxonomic identification. Here, we present the results of a large‐scale DNA barcoding study of Polish diplopod species (Myriapoda: Diplopoda), providing an up‐to‐date checklist of species recorded in Poland and a reference DNA barcode library. We deliver data on 981 individuals identified to species level, of which 468 have COI sequence data. 58 out of 93 species recorded for Poland were successfully barcoded, representing 62% of the national fauna. Additionally, we explore future research directions, potential cryptic diversity and shifts in the national fauna, including newly recorded species for Poland—Melogona broelemanni (Verhoeff, 1897). Our findings highlight the significance of ongoing monitoring and molecular methods in tracking biodiversity changes.

The epikarst, forming the uppermost layer of the vadose zone, is the interface between surface water and groundwater in karst aquifers, influencing hydrology and providing habitats for subterranean invertebrates. Epikarst invertebrates, including copepods, play important ecological roles. However, copepod taxonomic and molecular diversity in epikarst waters remains poorly understood. We examined diversity patterns and their relationship to environmental variation in epikarst seepage within the Demä nová Karst, Slovakia. Copepods were sampled monthly from May 2019 to July 2020, using 27 epikarst water filtering devices installed across four caves. Specimens were morphologically identified, largely to species level, and genetically characterised using mitochondrial COI barcode sequences. We quantified haplotype and nucleotide diversity, evaluated population structure, inferred demographic patterns and analysed relationships between environmental variables, copepod occurrence and assemblage composition. Analysis of 536 copepod individuals revealed distinct mitochondrial lineages within Elaphoidella and Bryocamptus species. Elaphoidella droppai showed signals consistent with recent expansion, whereas Elaphoidella phreatica exhibited more complex demographic patterns. Environmental variables, particularly drip rate, pH and ceiling thickness were associated with variation in copepod occurrence and assemblage composition. These results indicate that variation in both hydrological and structural characteristics of the epikarst influences copepod assemblages. The occurrence of multiple mitochondrial lineages within several species further suggests that species diversity in epikarst copepods may be underestimated when based solely on morphology. By integrating ecological measurements with genetic data, this study refines understanding of how environmental gradients and demographic processes shape copepod assemblages in epikarst habitats. Our findings highlight the importance of environmental conditions for the occurrence and composition of groundwater communities and demonstrate that morphology-based assessments alone may underestimate copepod diversity.

ABSTRACT Biological invasions pose major threats to ecosystems, with aquatic habitats particularly vulnerable due to high connectivity and biodiversity. The Ponto‐Caspian region is widely recognised as a major source of highly invasive non‐native aquatic species, yet a global synthesis of their spatial, taxonomic and temporal invasion patterns has been lacking. Here, we provide the first global review of the taxonomic diversity of non‐native aquatic Ponto‐Caspian species from published literature and biodiversity records, including information on invasion pathways, spatial distribution and temporal reporting trends. Our analysis of 146 non‐native aquatic Ponto‐Caspian species revealed a strong taxonomic bias, with arthropods (53%) and fishes (23%) accounting for over three‐quarters of recorded taxa, while crustaceans (Malacostraca) were markedly over‐represented relative to global non‐native aquatic taxa. Canal‐mediated connectivity among European waterbodies remained the dominant invasion pathway, whereas ballast water has been the primary pathway to North America. Geographically, invasions were concentrated in Europe and the Laurentian Great Lakes, with few records from other continents. From a temporal perspective, reporting showed fluctuating trends associated with canal construction, management actions and growing scientific attention. Overall, our findings suggest that invasion risks from Ponto‐Caspian species are largely context‐dependent, mainly affecting Europe and North America, but increasing trends highlight the need for strengthened prevention, control and international cooperation under ongoing environmental change.

ABSTRACT Aim Our research aimed to assess the beta diversity of Chironomidae (Diptera) and faunal connections across springs, streams, and rivers within the Skadar Lake basin, a Mediterranean biodiversity hotspot, using DNA barcoding. Location Skadar Lake basin—a Mediterranean biodiversity hotspot. Methods We analysed mitochondrial cytochrome c oxidase subunit I sequences from larvae collected at 56 sites, employing Barcode Index Numbers (BINs) as proxies for species. Results Our analysis revealed high overall diversity (224 BINs) along high site heterogeneity and a large proportion of rare BINs. Nearly two‐thirds of BINs were represented by fewer than four specimens, and 84% occurred at three or fewer sites. We observed extremely low faunal overlap between ecosystems, with only nine BINs shared among springs, streams, and rivers. Springs had the highest richness (169 BINs) and exceptional uniqueness, hosting 126 exclusive BINs (ca. 56%). No significant large‐scale geographical or altitudinal diversity gradients were detected, suggesting local factors override broader patterns. Main Conclusions The major conclusion is that hydrogeological isolation within the karst landscape profoundly shapes chironomid diversity, creating unique and isolated spring communities. These distinct, often rare assemblages indicate that chironomids are a sensitive indicator of habitat fragmentation and the vulnerability of these unique Mediterranean freshwater ecosystems to environmental change and localised impacts.

The International Barcode of Life (iBOL) initiative is building a globally accessible DNA-based system for species identification and discovery. This paper outlines the mission and strategic priorities for the iBOL community in Europe (iBOL Europe), set in a global context. The mission of iBOL Europe is to produce, curate, and provide access to a complete DNA barcode reference library of European eukaryotic biodiversity, catalyzing species discovery and enabling comprehensive, harmonized species identification and biomonitoring, and supporting the global iBOL program. Immediate objectives include completing reference libraries for priority taxa, democratizing access to sequencing technologies, and strengthening a distributed community of practice. Key actions identified span five thematic areas: community building, sample collection and taxonomic verification, sequencing infrastructure, data management, and mainstreaming DNA-based approaches to meet societal needs. The strategy emphasizes integration with European research infrastructures to ensure long-term sustainability and resilience for biodiversity genomics in Europe.

Environmental DNA (eDNA) has emerged as a transformative tool for monitoring aquatic biodiversity, offering a non-invasive and highly sensitive approach to detecting organisms across diverse ecosystems. However, its effective downstream application across Europe in environmental management is hindered by inconsistencies in data standardisation, metadata reporting, and accessibility. This perspective comprehensively evaluates current data repositories, data submission workflows, and standardisation efforts within the European aquatic eDNA landscape. By employing a multi-method approach, including an inventory of eDNA databases, a metadata assessment, a stakeholder questionnaire, and a generative Artificial Intelligence (AI)-driven analysis of scientific literature, our findings reveal substantial variability in metadata reporting practices, with several areas misaligned with Findable, Accessible, Interoperable, and Reusable (FAIR) principles. While some repositories demonstrate strong data curation and accessibility, others lack essential metadata descriptors, limiting interoperability. We identify critical gaps in metadata submission, particularly concerning sampling methods and wet lab workflows, which heavily impact data reusability. The use of generative AI in this study further enabled large-scale identification of recurring reporting weaknesses, highlighting structural challenges that extend beyond individual studies. Addressing these gaps and leveraging advanced computational approaches through international standards and harmonised guidelines represents a clear way forward, as articulated in the recent “Making eDNA FAIR” paper by Takahashi et al. (2025), which is based on the use of Darwin Core (DwC) and Genomics Standards Consortium (GSC) MIxS standards, as well as Global Biodiversity Information Facility (GBIF)’s “Publishing DNA-derived data through biodiversity data platforms” guidelines. Furthermore, additional complementary principles strengthen this framework. The Collective benefit, Authority to control, Responsibility, Ethics (CARE) principles emphasise Indigenous data governance and responsible sample stewardship, while the Transparency, Responsibility, User focus, Sustainability, Technology (TRUST) principles provide criteria for repository reliability and long-term digital preservation. Together, the combined application of FAIR, CARE, and TRUST principles provides a structured foundation for ensuring robust, interoperable, and ethically managed eDNA data that support aquatic biodiversity research, management, and conservation across Europe.

DNA barcoding has become a cornerstone for species identification and biodiversity monitoring, enabling applications from ecological research to conservation and environmental policy. The International Barcode of Life (iBOL) provides global coordination, but national nodes are essential for implementing barcoding at scale, building local capacity and translating scientific advances into practice. This paper synthesises experiences from 20 countries (17 in Europe), drawing on a survey and a workshop conducted under the Horizon Europe Biodiversity Genomics Europe project. We examine how national nodes are initiated, governed and sustained and identify common challenges, such as defining scope, securing funding, harmonising methods and engaging stakeholders. Most nodes were initiated by research communities and operate as informal networks with heterogeneous governance and staffing models. Key priorities include constructing comprehensive DNA barcode reference libraries, aligning activities with biomonitoring needs and promoting FAIR and CARE data principles. We highlight strategies for capacity building, methodological standardisation and stakeholder engagement, alongside approaches for diversifying funding and strengthening communication. Based on these insights, we present ten practical recommendations to guide the establishment and long-term success of national DNA barcoding nodes. Strengthening these infrastructures will enhance Europe’s ability to deliver robust DNA-based biodiversity monitoring, underpin metabarcoding and metagenomic studies and contribute to global efforts in species discovery, conservation and environmental management.

This study examines cryptic diversity and speciation processes within stygobiotic harpacticoid copepods of the genus Elaphoidella, which inhabit the epikarst of the Dem & auml;nov & aacute; Valley Karst in Slovakia. Using an integrative taxonomic approach, we employed molecular phylogenetic analyses of COI and 28S rRNA gene fragments, molecular species delimitation methods, and traditional taxonomy to describe a new species, Elaphoidella droppai sp. n. Genetic data revealed significant divergence between E. droppai sp. n. and E. phreatica, which was supported by distinct clustering in phylogenetic trees. Molecular species delimitation methods consistently identified E. droppai sp. n. as a separate evolutionary unit. Despite sharing the same swimming leg pattern, notable morphological differences were observed, particularly in the P5, the furca, and the row of spines on the anal segment. The highly reduced female P5 represents a unique feature within Elaphoidella. Further analysis of the genital segments of females in both species revealed significant differences in segment dimensions and genital pore structure, suggesting reproductive isolation. These findings demonstrate that karstic vadose zones, particularly the epikarst, can act as a driver of speciation in subterranean fauna and a reservoir of hidden biodiversity. This integrative taxonomic study not only expands the known diversity of Elaphoidella in the Carpathian region but also underscores the importance of integrating genetic and morphological data for species discovery and understanding evolutionary processes in isolated subterranean habitats.

Ponto-Caspian gammarids comprise dozens of endemic taxa. Many are invasive throughout the world, being exceptionally adaptable thanks to the dynamic geological history of the region where they have evolved. Many species described from the Caspian basin were found in the Pontic (Black Sea) basin only in the last century. It remains unclear whether they are native or non-native in this region. Herein, we investigate whether Amathillina cristata, originally described from the Caspian Sea and occasionally listed as an invasive species in the Black Sea, is in fact native to the Black Sea basin. To achieve this goal, we analyse molecular data from Ukraine and – for the first time ever – from Turkey; we also review the entire geographical distribution of the species. For descriptive purposes, we document for the first time the cuticle ultrastructure throughout the body, appendages and mouthparts using scanning electron microscopy. Our results show that A. cristata is distributed in the NW-W part of the Black Sea basin and all investigated Black Sea drainages contain unique haplotypes that appear to have been isolated since the Late Pleistocene, demonstrating that this species is native throughout this basin. Ultrastructure investigation revealed a uniform pattern of pores and sensilla throughout all body regions except the urosome. At least two colour morphs were observed in living specimens. We consider that this species is vulnerable, in particular the Ukrainian populations, due to the high anthropogenic pressure in the region. The destruction of the Kakhovka reservoir in June 2023 most likely affected the known populations in the lower reaches of the Dnieper and Southern Bug rivers.

The study of present-day species distributions often raises questions about historical demography. A particularly interesting phenomenon to put in historical context is contemporary human-induced atlantification and its role in reshaping Arctic ecosystems. Despite this, the colonisation history of the Arctic remains generally understudied. In this study, we investigated the demographic history of the northern acorn barnacle, Semibalanus balanoides, a typically boreal species on the Svalbard Archipelago. Our focus was to determine the source and timing of its colonisation of this Arctic archipelago. Using low-coverage whole-genome sequence data, we evaluated two competing hypotheses: whether S. balanoides populations colonised Svalbard through ancient natural processes before the Anthropocene, or if their appearance is more recent, either natural or a consequence of growing anthropogenic influences, such as increased connectivity and global warming. Our results suggest that this boreal species expanded into the Arctic during the later phase of the Holocene Thermal Optimum, well before human-induced climate change.

The expansion of myriapod species outside their native range is a well-known phenomenon, although well-studied only in the western part of Europe. Our study reports a recent rapid eastward range extension of Polydesmus angustus Latzel, 1884, from Germany to Poland, where its new eastern limit of distribution is probably the Vistula River. We confirm that the species occupies disturbed, anthropogenic habitats, supporting its human-mediated dispersal scenario. We also consider the possibility of competition between this species and its closest relative, Polydesmus complanatus (Linnaeus, 1761).We also point out that in the case of taxonomic groups containing externally similar species, the verification of citizen sciencebased records by specialists examining morphological details of specimens and, if possible, by DNA barcodes, is necessary for reliable insight into the range extension of alien species.

Cryptic species complexes-genetically divergent lineages with similar phenotypes may appear cryptic not due to true similarity, but because high within-species morphological variation masks interspecies differences, particularly in heterogeneous environments. This study tests whether such lineages exhibit morphological convergence across similar environmental gradients or context-dependent divergence, challenging their cryptic status. We propose a theoretical framework to assess phenotypic differentiation and apply it using the amphipod complex Gammarus roeselii, which diversified in the Balkan Peninsula before one lineage expanded into Central Europe. We examined five lineages across similar environmental gradients to evaluate their phenotypic divergence. Our findings confirmed their cryptic status. However, phenotypic differentiation along environmental gradients revealed MOTU-specific adaptive trajectories: traits under strong selection (e.g., anti-predator defences) showed convergent responses, while morphological (e.g., body length) and physiological traits (e.g., gill area) diverged, likely due to local selection. Some MOTUs exhibited distinct, partially divergent sexual dimorphism, suggesting varied reproductive or ecological strategies within cryptic lineages. Phenotypic variation was greater within than between MOTUs, reinforcing their cryptic status and revealing strong local adaptive responses. This complex exemplifies how adaptive divergence and biogeographic history jointly shape biodiversity, with morphological stasis despite genetic and ecological differentiation exposing hidden speciation and environmental responses.

Mayflies (Ephemeroptera) are among the crucial water and habitat quality bioindicators. However, despite their intensive long-term use in various studies, more reliable mayfly DNA barcode data have been produced in a negligible number of countries, and only similar to 40% of European species had been barcoded with less than 50% of families covered. Despite being carried out in a small area, our study presents the second-most species-rich DNA reference library of mayflies from Europe and the first comprehensive view from an important biodiversity hotspot such as the Western Carpathians. Within 1153 sequences, 76 morphologically determined species were recorded and added to the Barcode of Life Data System (BOLD) database. All obtained sequences were assigned to 97 BINs, 11 of which were unique and three represented species never barcoded before. Sequences of 16 species with high intraspecific variability were divided into 40 BINs, confirming the presence of cryptic lineages. Due to the low interspecific divergence and the non-existing barcoding gap, sequences of six species were assigned to three shared BINs. Delimitation analyses resulted in 79 and 107 putative species respectively. Bayesian and maximum-likelihood phylogenies confirmed the monophyly of almost all species and complexes of cryptic taxa and proved that DNA barcoding distinguishes almost all studied mayfly species. We have shown that it is still sufficient to thoroughly investigate the fauna of a small but geographically important area to enrich global databases greatly. In particular, the insights gained here transcend the local context and may have broader implications for advancing barcoding efforts.

The River Habitat Survey (RHS) is a method for assessing the conditions of a river channel and valley, taking into account hydromorphological factors, and assessing the degree of naturalness or the degree of anthropogenic alteration within the channel and valley based on physical and landscape data. The hypothesis tested in this study was that the quality of river habitats demonstrated using the RHS should translate into the composition of their fauna. We investigated aquatic bugs (Heteroptera Aquatica), which are a group with considerable dispersal abilities and, at the same time, composed of stenotopic species associated with a particular environment as well as of eurytopic elements inhabiting a wide range of environments (REF). The research was carried out in a small lowland river, the River Krąpiel (north-western Poland) at 6 sites with 43 sub-sites included. Our analyses suggest the RHS method can predict the composition and quality of the aquatic bug fauna inhabiting a given river. Indicators of river habitat quality (HQA and RHQ) will be associated with different habitat types depending on the geographic location and type of river, once indicating habitats associated with the mainstream river and mineral substrate (mountain and small lowland rivers) and at other times habitats covered by vegetation with relatively slow water flow (large and medium lowland rivers). Therefore, RHS may be a good method for estimating the water bug fauna, linking it to the size and character of the river.

Zamierzeniem badawczym tekstu jest próba muzeologicznej interpretacji i autorskiej analizy wystawy stałej ilustrującej dzieje Gdyni przy użyciu formuły „dzieła otwartego” proponowanej przez Umberto Eco. Udostępniona publiczności w 2017 roku ekspozycja oferuje szereg mikrohistorii bazujących na losach anonimowych mieszkańców, a w kreowaniu narracji wykorzystuje przedmioty/eksponaty do niedawna należące do prywatnych właścicieli. „Dzieło otwarte” to nie tylko parafraza zwrotu „miasto otwarte”, ale i zachęta do tworzenia własnej ścieżki zwiedzania i budowania z tych dostępnych tropów własnego obrazu miasta i jego „wyobrażonego potencjału”. Antropologia codzienności, prezentowanie losów anonimowych, nieznanych z historii mieszkańców oraz przenikanie się licznych tropów linowych, sieciowych i hipertekstowych to elementy stanowiące prymarne założenia tego projektu. Oprócz analizy dyskursu wizualnego i werbalnego przybliżone zostaną założenia modelu wystawy prezentującej miasto, które wykorzystuje założenia wystawy narracyjnej w nieco odmienny sposób.