The significance of long-term biodiversity monitoring studies for the protection of natural biodiversity and human well-being is well recognised by the Turkish scientific community. Despite understanding the ecological importance of freshwater ecosystems, spatially or temporally congruent studies using high resolution biodiversity monitoring data from Turkish freshwater resources remain scarce. To determine a biodiversity baseline for future studies, biological and environmental sampling was carried out in 15 different locations from the highly anthropogenically impacted Bakırçay River and its catchment in Western Anatolia between 2017 and 2018. A total of 17 fish species from 10 families were recorded, belonging mainly to the Cyprinidae and Leuciscidae families. These included six non-native, six regionally endemic, and five native species. The endangered endemic Alburnus attalus was the most widespread species, whereas several non-native species were restricted to single sites. Patterns in community composition were primarily associated with pH and stream order. However, community metrics such as species richness, Pielou's evenness, and the Shannon-Wiener diversity index were not significant. Intensifying anthropogenic activity within the Bakırçay basin suggests that sources of pollution and other detrimental stressors like non-native species should be managed to protect riverine biodiversity and maintain the provision of ecosystem services. Our findings therefore not only present a baseline for future studies on fish biodiversity and community composition, but also the possible onset of future monitoring studies in the region. Our findings underline the importance of long-term biomonitoring studies for the conservation of Türkiye's freshwater ecosystems to monitor changes occurring over time.

• Klíčová slova
• Bakırçay river, Ecological modeling, Fish ecology, Freshwater fish, West anatolia,
• MeSH
• biodiverzita * MeSH
• Cyprinidae MeSH
• ekosystém * MeSH
• monitorování životního prostředí MeSH
• řeky * chemie   MeSH
• roční období * MeSH
• ryby * klasifikace   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Turecko MeSH

The introduction of non-native aquatic species has fundamentally transformed aquatic assemblages, primarily due to human activities, such as aquaculture, fisheries enhancement, aquarium trade, the creation of artificial corridors, and deliberate and accidental releases. Despite growing concern for biological invasions, there is no overall global appraisal of successful non-native fishes. This study compiled a comprehensive dataset from several global sources to examine the taxonomic diversity, geographical distribution, introduction pathways, and ecological impacts of non-native freshwater and marine fishes. Our dataset includes 1535 established non-native fish species in 193 countries (82% of the global coverage), with Leuciscidae, Cichlidae, Salmonidae, and Cyprinidae being the most represented families. Although the incline in first reportings appears almost linear, annual reporting has been declining for decades, suggesting fish introduction rates are decreasing. The main introduction pathways are aquarium trade, aquaculture, fishery augmentation, and the creation of artificial corridors. The importance of introduction pathways substantially differed between freshwater species (primarily the aquarium trade and aquaculture) and marine species (corridors). While extensive records exist for hundreds of non-native fish species, information on their impact types and impact mechanisms remains available only for a third of these species, highlighting broad knowledge deficiencies. Available impact information indicates that non-native fish species may threaten native biodiversity through primarily competition and predation as dominant mechanisms. The magnitude of highest-risk invasions suggests remediation is possible through urgent proactive policy and management interventions. This comprehensive global evaluation of established fish species and their ecological effects thus addresses critical data deficiencies, strengthens risk assessment frameworks, and supports the development of targeted biosecurity policies on priority pathways, approaches essential for helping mitigate the environmental and economic impacts of non-native fish introductions.

• Klíčová slova
• aquatic ecosystem, aquatic habitat, biological invasion, freshwater ecosystem, introduction pathways, invasive species,
• MeSH
• biodiverzita * MeSH
• rybářství MeSH
• ryby * fyziologie   klasifikace   MeSH
• vodní hospodářství MeSH
• zachování přírodních zdrojů * MeSH
• zavlečené druhy * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Assessing actual and potential impacts of non-native species is necessary for prioritising their management. Traditional assessments often occur at the species level, potentially overlooking differences among populations. The recently developed Dispersal-Origin-Status-Impact (DOSI) assessment scheme addresses this by treating biological invasions as population-level phenomena, incorporating the complexities affecting populations of non-native species. We applied the DOSI scheme to the non-native and translocated species reported in a shallow alluvial lake (Lake Gala) and a reservoir (Sığırcı Reservoir) in north-western Türkiye. DOSI identified 12 established species across both ecosystems, including nine fish, two invertebrates, and one mammal. Most species received High and Medium-High priority rankings, in both sites. In contrast, Medium and Low priority rankings were less common, each occurring once in Lake Gala and four times in Sığırcı Reservoir. These high-priority species warrant targeted management interventions due to their established status, autonomous spread, and observed negative impacts. By enabling a more nuanced and context-specific approach, DOSI facilitates the development of targeted strategies for managing species posing the highest risks. Moreover, DOSI's focus on population-level assessment within ecosystems is highly relevant for stakeholders, decision-makers, and environmental managers, because it provides a more detailed and precise unit of evaluation.

• Klíčová slova
• Callinectes sapidus, Gymnocephalus cernua, Myocastor coypus, Biological invasions, Invasive species, Lake Gala, Sığırcı reservoir,
• MeSH
• bezobratlí MeSH
• biodiverzita MeSH
• ekosystém * MeSH
• jezera * MeSH
• ryby MeSH
• zachování přírodních zdrojů * metody   MeSH
• zavlečené druhy * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Biological invasions are a major threat to global biodiversity, with freshwater ecosystems being among the most susceptible to the successful establishment of non-native species and their respective potential impacts. In Poland, the introduction and spreading of non-native fish has led to biodiversity loss and ecosystem homogenisation. METHODS: Our study applies the Dispersal-Origin-Status-Impact (DOSI) assessment scheme, which is a population-level specific assessment that integrates multiple factors, including dispersal mechanisms, origin, status, and impacts, providing a nuanced framework for assessing invasion risks at local and regional levels. We used this tool to evaluate the risks associated with non-native fish species across three major Polish rivers (Pilica, Bzura, and Skrwa Prawa) and to prioritise them for management actions. RESULTS: Using DOSI, we assessed eight non-native species identified in the three studied rivers: seven in both Pilica and Bzura and four in Skrwa Prawa. The DOSI assessment scheme identified high variability in the ecological impacts and management priorities among the identified non-native species. Notably, species such as the Ponto-Caspian gobies exhibited higher risk levels due to their rapid spread and considerable ecological effects, contrasting with other species that demonstrated lower impact levels and, hence, received a lower priority for intervention. CONCLUSION: The adoption of the DOSI scheme in three major rivers in Poland has provided valuable insights into the complexities of managing biological invasions, suggesting that localised, detailed assessments are crucial for effective conservation strategies and highlighting the importance of managing non-native populations locally.

• Klíčová slova
• Biological invasions, Invasive species, Risk assessment, Species management,
• MeSH
• biodiverzita * MeSH
• ekosystém MeSH
• řeky * MeSH
• ryby * MeSH
• zachování přírodních zdrojů metody   MeSH
• zavlečené druhy * MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Polsko MeSH