Wetlands provide essential ecosystem services for human well-being but despite their importance, they continue to disappear globally and with them, their biodiversity. A major threat to wetland biodiversity are biological invasions. This study therefore aims to assess the spread and ecological impacts of populations of non-native and translocated species in three wetlands (Lake Manyas, Lake Uluabat, and the Kocaçay Delta) located in the Marmara Region of Türkiye. For this, we used the recently developed Dispersal-Origin-Status-Impact (DOSI) framework, which allows for a holistic analysis of (i) how non-native species are dispersed, (ii) their origin, (iii) their current population status, and (iv) impacts on a given assessment area. Through this application, a total of 34 population-based assessments were conducted, reflecting the distribution of 18 species of fish, macroinvertebrates, and plants; seven of which being identified in all three ecosystems, two in two, and only nine in a single ecosystem. The majority of species were intentionally introduced to the region through human actions such as fisheries, bio-control, and recreational activities. Carassius gibelio, Gambusia holbrooki, Physella acuta, and all plants stand out as the species presenting the highest threat according to the DOSI scoring. These species’ effects, such as altering habitat structure, competing with native species and disrupting trophic networks, threaten the ecological integrity of these wetlands. Early intervention and long-term control strategies should be developed, especially for species with high impact levels.

This study investigated the length–weight relationships (LWRs) and condition factors (CF) of five fish species (Atherina pontica, Engraulis encrasicolus, Neogobius melanostomus, Chelon auratus, and Knipowitschia caucasica) inhabiting the Küçükçekmece Lagoon (Istanbul, Türkiye). Fish samples were collected using gillnets and seine nets between September 2023 and August 2024. A total of 1213 individuals from five fish species were analyzed for LWR and CF. The allometric coefficient (b) estimated from the linear regression model of the LWR ranged from 3.071 for A. pontica to 3.454 for N. melanostomus, it was determined that the relationships of the species examined exhibited allometric growth. The coefficient of determination (R2) values of the LWRs ranged from 0.9581 (E. encrasicolus) to 0.9897 (C. auratus). Fulton’s CF values ranged from 0.27 in E. encrasicolus to 2.00 in K. caucasica. This study provides the first report of LWR and CF parameters for four species (E. encrasicolus, N. melanostomus, C. auratus and K. caucasica) in this lagoon. These findings contribute to future assessments of ecosystem health and its impact on fish growth within the lagoon basin.

The small killifish Aphanius almiriensis (Kottelat, Barbieri & Stoumboudi, 2007) inhabits from brackish springs to estuaries and coastal lagoons in the eastern Mediterranean basin. This study focused on the detailed characterization of Aphanius almiriensis from a hypersaline geothermal spring (Tuzla, Çanakkale, NW Anatolia), where extreme salinity (61.14 ppt in winter, January 2023) and temperature (42.7°C in summer, July 2023) conditions were observed. The obtained specimens of killifish in the sampling site, with a slightly convex dorsal head profile and a more angular ventral head profile, are similar in this respect to specimens from Greece. In most individuals (25 out of 27), the two frontal scales do not contact each other. Genetic analyses indicate that the species exhibits a minimum p-distance of 3.1% from Aphanius fasciatus in the mitochondrial cytochrome c oxidase subunit I (COI) region. Although previously reported, this population had not been thoroughly characterized up to date; however, based on the present study, it exhibits genetic and morphological characteristics consistent with A. almiriensis specimens from Greece.

Abstract The small killifish Aphanius almiriensis (Kottelat, Barbieri & Stoumboudi, 2007) inhabits from brackish springs to estuaries and coastal lagoons in the eastern Mediterranean basin. This study focused on the detailed characterization of Aphanius almiriensis from a hypersaline geothermal spring (Tuzla, Çanakkale, NW Anatolia), where extreme salinity (61.14 ppt in winter, January 2023) and temperature (42.7°C in summer, July 2023) conditions were observed. The obtained specimens of killifish in the sampling site, with a slightly convex dorsal head profile and a more angular ventral head profile, are similar in this respect to specimens from Greece. In most individuals (25 out of 27), the two frontal scales do not contact each other. Genetic analyses indicate that the species exhibits a minimum p‐distance of 3.1% from Aphanius fasciatus in the mitochondrial cytochrome c oxidase subunit I (COI) region. Although previously reported, this population had not been thoroughly characterized up to date; however, based on the present study, it exhibits genetic and morphological characteristics consistent with A. almiriensis specimens from Greece.

This study offers the first detailed investigation of the ichthyofauna of the K & uuml;& ccedil;& uuml;k & ccedil;ekmece Lagoon (& Idot;stanbul, T & uuml;rkiye) in nearly 30 years, with the aim of characterizing the current structure of the fish community in this anthropogenically pressured lagoon. Seasonal samplings were conducted between September 2023 and August 2024, and fishing was conducted at five different stations within the lagoon using multimesh gillnets and at two coastal sites using a seine net. A total of 18 fish species belonging to 12 families were identified. Only five species (Atherina pontica, Engraulis encrasicolus, Chelon auratus, Chelon ramada, and Mugil cephalus) were captured using gillnets. On the other hand, 17 species were recorded with a seine net in areas close to the lagoon's connection with the Sea of Marmara. Atherina pontica was the most abundant species in both fishing methods, while Salaria pavo, Belone belone Neogobius fluviatilis, Gobius niger, and Sparus aurata were each represented by a single specimen. The current species composition indicates a community dominated by euryhaline species, which differs from historical records that included freshwater taxa. The absence of freshwater species in the catch coincides with the observed salinity levels (up to 14.12). Except for a few resident species (e.g., A. pontica and E. encrasicolus), the lagoon is predominantly inhabited by euryhaline species, especially during spring and summer. Serving as a structured baseline, this study documents the current ecological status of fish assemblages in the lagoon following long-term environmental change.

An alternative strategy to mitigate the ecological and economic challenges posed by invasive fish species is to transform these organisms into valuable resources, generating economic benefits while simultaneously addressing ecosystem-related concerns. However, while the search for sustainable feedstocks continues, the specific potential of highly resilient invasive fish species for high-yield biodiesel production has not yet been evaluated. The aim of this study was to address this research gap by producing high-yield biodiesel using the invasive fish Carassius gibelio as an oil source. In this context, lipase immobilized MnFe2O4- polyhydroxymethyl methacrylate magnetic nanogels were prepared and the production system conditions (lipase amount, methanol/oil molar ratio, and temperature) were optimized. Optimal conditions were obtained using a 4000 U lipase amount, a 5:1 methanol/oil molar ratio and a temperature of 55 °C. A 97.45% biodiesel yield was achieved with this system prepared under optimum conditions, and this prepared biocatalysis system was able to produce biodiesel with at least 50% yield 13 times. This study is the first to use the highly invasive C. gibelio as a sustainable raw material for biodiesel production. It introduces a novel biocatalytic approach by integrating invasive fish species utilization with a reusable MnFe2O4-pHEMA nanogel system, achieving both high efficiency and operational stability.

Background Synaptula reciprocans, originally native to the Indo-Pacific region, is widespread in the Red Sea. The species entered the Mediterranean during the 1970s and 1980s and has been reported along the Turkish coastline since 2003, where it has established invasive populations. European Union Regulation No. 1143/2014 encourages the investigation of alternative uses and the assessment of the economic potential of invasive species as part of management and control strategies. This study aims to evaluate the nutritional value and elemental composition of S. reciprocans, an invasive species in the Mediterranean, in order to assess its suitability for human consumption and potential alternative applications. Methods S. reciprocans were sampled from two different stations (L1: Gokova Bay and L2: Gulluk Bay) over two seasons, as winter (S1) and summer (S2), and transported to the laboratory under cold chain conditions (+4 °C). Moisture, ash, crude protein, crude fat, fatty acid, amino acid, and elemental content analyses were performed using standardized methods, including gravimetric, Kjeldahl, GC/MS, LC/MS-MS, and ICP-OES techniques. Results The findings indicate that both locality and season significantly influence the species’ nutritional properties (p < 0.05). Dry matter content exhibited considerable variation across seasons, with the highest concentration observed in L2/S2 and L2/S1. Crude protein levels peaked in winter across both regions (L2S1, L1S1), while fat content was consistently higher in Bodrum samples compared to Gokova (p < 0.05). Ash content was highest in Gokova across both seasonal periods (p < 0.05). The fatty acid profile demonstrated notable seasonal and regional differences (p < 0.05), with linoleic acid (C 18:2) emerging as the predominant polyunsaturated ω-6 fatty acid. Additionally, amino acid analysis revealed significant variation (p < 0.05), identifying alanine, asparagine, glutamine, and proline as the dominant amino acids. Elemental analysis highlighted the absence of copper (Cu) in all sampled tissues, while sodium (Na) was consistently the most abundant mineral.

Objective: Bithynia gonensis D. A. Odabaşı, 2024 is a narrowly endemic freshwater snail restricted to the Gönen Stream in northwestern Türkiye. Despite the reported diversity of Bithyniidae in Türkiye, species identifications have largely relied on morphologic characteristics without molecular support. This study aimed to investigate the phylogenetic position of B. gonensis using mitochondrial COI barcode data.Materials and Methods: Specimens were collected from the type locality, and genomic DNA was extracted from foot tissue. A partial fragment of the mitochondrial cytochrome c oxidase subunit I gene was amplified using modified LCO/HCO primers. Sequences were aligned and analyzed in MEGA X, and phylogenetic relationships were inferred using the neighbor-joining method based on uncorrected p-distances with 1000 bootstrap replicates.Results: The analyses revealed that B. gonensis forms a distinct and well-supported monophyletic lineage. It appears as a sibling group to a clade comprising Bithynia sp. from Lake Eğirdir and B. zeta Glöer & Pešić, 2007, with moderate bootstrap support. The species shows clear genetic divergence from B. tentaculata and B. cettinensis.Conclusion: This study provides the first molecular data for a bithyniids species from Türkiye and supports the distinct taxonomic status of B. gonensis. The findings emphasize the importance of integrating molecular approaches into the taxonomy of Turkish freshwater gastropods.

Biological invasions, driven by the spread of non-native species, have become a critical global issue because of their far-reaching ecological and socioeconomic impacts. Effective communication of the risks of biological invasions is essential for implementing robust policy and legislation and gaining public support for conservation efforts. However, current policies often suffer from fragmentation and ineffectiveness, largely due to inadequate risk communication and complex multi-level governance. To address this challenge, we develop a global framework designed to enhance clearer communication about biological invasion risks. The framework contextualizes key terms across three domains in invasion science: species invasiveness, risk analysis, and decision support tools. Using both diffusion-of-English and ecology-of-language paradigms, and following a three-step process involving preliminary consensus, AI querying, and ground-truthing with final consensus, we validate the framework in 70 non-English languages which, together with English, have official status in at least one country and collectively cover all 195 countries worldwide. Our findings reveal that while terminology for risk analysis is well established, terminology for species invasiveness and, especially, for decision support tools remains underdeveloped in many languages, hindering effective communication and policy implementation. Our framework underscores the importance of cultural and political neutrality. By promoting clearer risk communication among scientists, policymakers, and the public globally, we aim to reduce policy fragmentation and foster enhanced collaboration in risk mitigation. We recommend expanding multilingual decision support tools to include the full risk analysis process: risk identification, risk assessment, and risk management. This will support intergovernmental mitigation efforts and promote a unified global response to biological invasions.

This study aims to understand the bioecological traits of an extremophile fish, Aphanius almiriensis, in order to explore how it survives and colonizes extreme habitat conditions. To achieve this, the bioecological characteristics-condition, diet, and feeding strategy-of A. almiriensis inhabiting the Tuzla thermal spring, which is characterized by extreme habitat conditions in terms of physicochemical water parameters, were studied. Among the physicochemical parameters measured, salinity and temperature were remarkably high, ranging from 23.7°C (in winter) to 42.7°C (in summer) and from 47.7 ppt (in autumn) to 60.7 ppt (in winter). A total of 248 fish individuals were collected from the thermal spring, and the diet analyzed seasonally consisted of 17 different food items, and their importance values (MI% and IRI%) varied seasonally. According to the F%, IRI%, and MI% values, the population fed mainly on Diatom, Cyanobacteria, and Diptera, resulting in niche breadth with low values ranging from 0.25 to 0.54. The extreme conditions of the thermal spring indicated that the environment was poor in terms of macroinvertebrate diversity (six taxa), and fish showed food selectivity (E) for Chironomidae and Ceratopogonidae in winter, spring, and summer and for Ephydridae in autumn (E > 0; positive selectivity). Seasonally influenced fish condition was represented by high values in summer (K = 1.43 ± 0.14) and was positively correlated with both water temperature and the increasing importance of the genus Phormidium in its diet. This study provides the first comprehensive insight into the seasonal diet and condition of A. almiriensis, shedding light on its survival strategies in harsh ecological conditions.

The Eastern mosquitofish Gambusia holbrooki Girard, 1859, has been widely introduced into tropical and temperate countries as a biological agent to control mosquitos, which are associated with diseases such as malaria and yellow fever. However, the species exhibits invasive characteristics by competing with native species for food and habitat use. This study investigates the feeding ecology of G. holbrooki populations from three distinct freshwater environments (Lake Iris, Eğlenhoca Reservoir, and Parlak Reservoir) on the Karaburun Peninsula (North-Western Türkiye), a region outside its native range. The primary aim was to evaluate seasonal and spatial variations in the diet of the species. A total of 871 specimens were analysed: 247 from Iris Lake, 318 from Parlak Reservoir, and 306 from Eğlenhoca Reservoir. Low percentages of empty stomachs (≤20%) across all populations indicate high feeding intensity. The results reveal that G. holbrooki exhibits a generalist feeding strategy, consuming a wide range of food items such as insects, zooplankton, and plant material across all the investigated environments. The relative importance of food groups (determined by the Importance Index, MI%) varied seasonally but not spatially. In all three populations, the most important food source in the spring was dipterans, followed by plants in the summer and fall, and cladocerans in the winter. Plants accounted for the largest percentage of the diet in every population (MI% >65%). These findings suggest that G. holbrooki adapts its diet to seasonal food availability.

This study reports the recent discovery of the pumpkinseed Lepomis gibbosus in the Bayramiç Reservoir, which is located in the Karamenderes Basin (NW Türkiye). A total of five specimens were captured with a portable electrofishing unit. Total length (TL) and body weight (W) measurements were recorded with an accuracy of 0.1 cm and 0.01 g, respectively. The length and weight ranges of the specimens were 41–88 mm and 7.2–14.3 g, respectively. The presence of this non-native species in the study area could be attributed to either natural expansion or multiple (deliberate/indeliberate) introductions.

Multiple factors can facilitate invasion success, with the absence of natural enemies, such as predators and parasites, recognised as conferring a significant advantage on invasive over native species. Pumpkinseed Lepomis gibbosus (Centrarchidae) represents one of the most successful freshwater fish invaders in Europe. Previous research has highlighted genetic differences between pumpkinseed populations in Türkiye and those in other European regions, attributed to rapid adaptation to new environmental conditions. This study aimed to investigate whether these highly adapted pumpkinseed populations in Türkiye benefit from a potential release from parasites, as proposed by the enemy-release hypothesis. Genetic characterisation of pumpkinseed populations from both European and Asian parts of Türkiye revealed that they share the same cytochrome c oxidase I haplotype as European populations. Microsatellite analysis indicated low genetic diversity, with STRUCTURE analysis confirming the clustering of all Turkish populations, suggesting a common source. Consistent with the low genetic diversity indicative of a small founding population, we observed a limited number of co-introduced parasite species, including the myxozoan Myxobolus dechtiari, the monogenean Onchocleidus dispar, and the digenean Posthodiplostomum centrarchi. Parasite infection by local parasites acquired in Türkiye was rare. Parasite diversity, species richness, and equitability were low, with only nine parasite taxa identified in all four pumpkinseed populations. The most diverse parasite community was found in Değirmenköy Reservoir, located in the European part of Türkiye, where seven parasite taxa were identified. While our study did not uncover genetically distinct pumpkinseed populations in Türkiye, the fish demonstrated resilience against most local parasite species, potentially providing them with an advantage over native species, aligning with the enemy-release hypothesis.

Petroleuciscus borysthenicus is a species with a wide distribution from the eastern, western, and northern Black Sea and Azov Sea basins, the Aegean Sea basin, and Northwestern Türkiye. However, there has been relatively little attention on the genetic variability of this species in their native distribution range, and nearly no study has been conducted in Türkiye despite its importance in biodiversity. The aim of this study was to elucidate the genetic variability and population structure of P. borysthenicus from Northwestern Türkiye using an integrated molecular method. A total of 72 specimens were collected from 13 localities in the Northwestern part of Türkiye. A total of six haplotypes were identified in all specimens. A relatively low level of genetic variability was found for P. borysthenicus throughout the study region based on the indices of genetic diversity including haplotype diversity and nucleotide diversity for the cytochrome oxidase subunit I (h = 0.507, π = 0.0027). The pairwise FST values between the samples ranged from −0.123 to 1.000. Furthermore, our results revealed no provable recent demographic expansion for P. borysthenicus from Northwestern Türkiye. However, more studies using additional geographic sampling and molecular analysis are needed to enhance our knowledge of the diversity and distribution of this species.

Despite the widespread occurrences of development plasticity in non-native populations, its underlying causes and consequences for species fitness remain unclear. This study aims to assess the potential invasion characteristics of Gambusia holbrooki in different habitats (lotic vs. lentic) of an island ecosystem (Gökçeada, Turkey), by using metrics related to growth and diet. Fish specimens were collected by electrofishing quarterly between September 2019 and July 2020 in Büyük Stream and the shorelines of the Uğurlu Reservoir. The growth metrics of the species were similar in both habitats, showing positive allometry (b > 3) and high condition (K > 2). The vacuity index (VI), showing low values for each habitat (12.7 in lotic vs. 19.3 in lentic), was a mark of high feeding density of the species. Aquatic insects and zooplankton were the main food items in the diet of this invasive fish, and it exhibited generalist feeding habits with specifics depending on the habitats. Because the species fed heavily on Diptera in the lotic habitat and Cladocera in the lentic habitat, niche breadth values were low (0.16–0.22). It was determined that different habitat types did not have an effect on the LWR and condition of G. holbrooki, but changed its feeding strategy. Positive allometric growth and good condition, a comprehensive food range, high levels of feeding density, and high nutritional plasticity can be considered essential parameters in explaining the invasion success of this fish species living in two different habitat types.

Geographical barriers to invasive species dispersion are being acceleratingly annihilated by human actions through deliberately or accidentally introductions as species were translocated of their region to the new environment across the world. Molecular markers could be useful to comprehend invasion scenarios of non-native species within this context. The aim of this study was to elucidate genetic diversity and dispersal patterns of non-native species ( Carassius gibelio , Gambusia holbrooki and Pseudorasbora parva ) from the westernmost part of Turkey, Gökçeada Island using mitochondrial COI marker. The present results discover three main findings: (i) a total of 13 haplotypes from COI was detected of which 11 were unique; (ii) high genetic diversity was determine for all non-native species ( h = 0.680 and π = 0.0023 for C. gibelio , h = 0.776 and π = 0.0027 for G. holbrooki , and h = 0.479 and π = 0.0262 for P. parva ); (iii) non-native species may have entered Turkey first from over Europe (i.e., invasive zone) after being introduced from their native distribution areas and then into Gökçeada Island from the mainland (i.e., Anatolia) through common stocking practices. The results of the present study indicated that non-native species were translocated or still being introduced to the Island. If the findings of this study are evaluated by public associations, the management activities can be better arranged on non-native species for the Island.

Bio-ecological studies and life-history traits of small-bodied fishes are critical for the understanding of their ecolog-ical role as well as the assessment of their position and continuity in the ecosystems. The current study goals to present initial data on growth and feeding habit of small-bodied Petroleuciscus borysthenicus inhabited in an island ecosystem (Gökçeada, Turkey). During the seasonally sampling surveys from May 2020 to January 2021, a total of 163 specimens were collected from Şahinkaya Reservoir using electrofishing. SL and W values of samples ranged from 2.6–10.0 cm and 0.32–25.68 g, respectively. LWR and K values were estimated for all specimens as W=0.017×SL3.114 (r=0.988) and 2.04 (±0.28), respectively. F:M sex ratio was calculated as 1:1.33 with no signifi-cant difference from the ratio of 1:1 (2=0.02; p>0.05). Diet of the species comprised of ten different food items. Plant (63.6%) was the most preferred food item from the point of frequency of occurrence (F%), pursued by Dip-tera (31.8%) and Odonata (12.7%). According to IRI (%) values of food items, Diptera was the dominant food item in all seasons. B and BA values were estimated as 3.18 and 0.24, respectively. The results showed that P. borysthenicus was more selective on conveniently accessible food materials in the environment and its food pref-erence was affected by seasonal food supply.

Objective: Fish can be used as bio-indicators to determine whether freshwater habitat has been altered. As habitat discontinuity occurs due to the presence of mechanical barriers, species composition can be altered upstream and downstream. Since the beginning of the 1980s, the amount of European eel Anguilla anguilla entering inland waters in Türkiye and European countries has decreased significantly. Our study describes for the first time the presence of A. anguilla from the freshwater bodies in the Karaburun Peninsula. Materials and Methods: From November 2020 to August 2021, fish specimens were collected through electrofishing in one lotic system and three transitional waters of the study area. Clove oil was used to anesthetize live fish specimens after capture. Total length (TL) was measured for each sample to the nearest 1.0 mm. With a digital balance that was accurate to 0.01 g, we weighed the total body weight (W). Results: We collected four adult specimens of A. anguilla from the study area. Total lengths and body weights of the specimens were 311 mm and 62.4 g for Balıklıova Stream; 360 mm and 95.3 g for Küçükbahçe Stream; 325 mm 56.3 g for Salman Reservoir and 280 mm and 34.7 g for Yelkentaş Stream, respectively. Conclusion: We could not discuss our findings since no study has been done in the study area before, but it is thought that the low number of individuals caught may be related to the habitat degradation and different types of constructions at the stream mouths. The construction of fishways suitable for the study area can be a start to solving the distribution problem of this species.

Abstract Pterois miles (Bennett, 1828), one of the most destructive marine invaders, was reported from the Mediterranean in 1991. It has invaded most parts of the Mediterranean from 2013, when it was reported for the second time, until today. On 7th October 2020, a single specimen of P. miles was collected by the bottom trawl from the Edremit Bay (Northern Aegean Sea). COI barcode region was used for the molecular identification of the specimen. DNA barcode data suggest that the specimen used in the present study is P. miles with a 99.69% probability. The current study is presented by providing the northernmost occurrence of the P. miles from the Aegean Sea with molecular confirmation.

The present study aims to investigate the condition, length-weight (LWRs) and length-length relationships (LLRs) of four introduced freshwater fish species (Carassius gibelio, Cyprinus carpio, Gambusia holbrooki, and Pseudorasbora parva) inhabited in the inland waters of Gökçeada (Çanakkale, Turkey). Fish samples were collected using electrofishing from one lentic (Büyük Stream) and four lotic (Aydıncık, Dereköy, Gökçeada, and Uğurlu Reservoirs) ecosystems between April 2019 and September 2020. The calculated values of parameter b in the LWRs were 3.275 and 3.230 for G. holbrooki (Uğurlu and Büyük populations, respectively), 3.031 and 2.937 for C. carpio (Aydıncık and Dereköy populations, respectively), 3.129 for C. gibelio and 3.047 for P. parva. Values of Fulton's condition factor (K) varied between 1.72 ± 0.23 (P. parva, Gökçeada population) and 3.60 ± 0.33 (C. carpio, Dereköy population). The coefficients of correlation (r) for all the LLR equations were greater than 0.95 and significantly linear. The present study provides the first knowledge about the selected biological parameters for four introduced freshwater fish species in Gökçeada.