Danube river which flows through ten European countries serves as an important resource for human life, agriculture and industry. The anthropogenic activities, especially those in the upper stream, put an environmental pressure on the river which need to be monitored and prevented. Faxonius limosus sampled in the polluted area of Danube in Serbia (Slankamen municipality), was studied as the test animal for the bioaccumulation of selected toxic and potentially toxic metals. Uptake and potential accumulation of the cadmium (Cd), arsenic (As), lead (Pb) and mercury (Hg) by abdominal muscles, hepatopancreas and exoskeleton were measured by MP-AES and data compared with metadata from the available references. The study found that metal uptake was indeed occurring, with significant levels detected in some tissues. Data provided should draw attention on the food chain risks of the studied crayfish, while at the same time, analysis can serve as the bioindicator of the pollution in the studied area, especially that of the sediment.

The rapid spread of invasive crayfish poses a major threat to freshwater biodiversity, making the assessment of newly established populations essential for understanding invasion processes and supporting effective management. The invasive spiny-cheek crayfish has been present in Serbia for more than two decades and has progressively expanded from the Danube into major tributaries, smaller watercourses, and reservoirs. This study aimed to assess the population structure and sexual dimorphism of the recently established spiny-cheek crayfish population in the Ćelije Reservoir using linear and geometric morphometric approaches and condition indices. A total of 63 individuals were analysed. The population was characterised by a balanced sex ratio, a high proportion of mature individuals, pronounced sexual dimorphism, and clear differences in condition indices between sexes. Males were generally larger, heavier, and in better condition than females, while sexual dimorphism was primarily reflected in the morphology of the chelae, cephalothorax, and cephalon. These findings provide new insights into the population structure of this invasive species in a reservoir habitat and suggest that the observed population characteristics are consistent with favourable conditions for its persistence in the Ćelije Reservoir. The results establish a valuable baseline for future ecological studies and invasion monitoring and highlight the importance of integrating long-term population monitoring with timely prevention, containment, and control measures tailored to local ecological conditions. Such an integrated approach should support evidence-based management strategies to reduce the ecological impacts of invasive crayfish and protect native freshwater biodiversity.

Macrobrachium nipponense (De Haan, 1849) is a highly resilient and prolific decapod species. Owing to its ecological flexibility, this East and Southeast Asian native prawn has begun spreading across the globe during the second half of the 20th and early 21st century. The Danube basin is one of its main recipient areas in Europe (already established in Ukraine, Moldova, Romania, Bulgaria, Hungary, and Germany), with most records being quite recent. Here, we report the first findings of M. nipponense from Serbia. Three specimens of the Oriental river prawn were independently caught at three different sites, namely the Sava River above Belgrade, the Danube in Veliko Gradi & scaron;te, and the confluence of the Danube with the Boljetin River close to Lepenski Vir during routine biological monitoring in 2025. These sites span around 175 river kilometres, with the latter two bordering Romania. The present findings increase the total number of non-native decapod species for the Serbian fauna to four. Considering the species' habitat preferences and ongoing climate change, its further spread in Serbian waters, as well as in central and northern Europe, can be expected.

In the Western Balkans, fishery management and legislation do not recognize the high molecular diversity of native brown trout. For this reason, stocking of streams relies on brown trout of non-native origin. In recent years, there have been new findings about the life-history features, dispersal and molecular characterisation of nominal taxa of brown trout in the Western Balkans. This has prompted to a re-evaluation of their risk of invasiveness in the region. In this study, based on a screening of six non-native lineages of brown trout, four lineages were ranked as high risk and two as medium risk of invasiveness under current climate conditions, whereas one lineage was ranked as high risk and the other five as medium risk under predicted global warming scenarios. Variation in scores and risk outcomes were related to life-history traits differing among lineages, with most pronounced differences in dispersal mechanisms. The results of this study point to the need for improvement of relevant legislation in several sectors of fishery management. Management strategies should aim to mitigate the conflicts arising among stakeholders, which contribute to the deterioration of the native traits of brown trout stocks throughout the Western Balkans.

The study was conducted on the Obedska Bara Ramsar site at two localities, Krstonošića okno and canal Vok, to provide insight into fish community status by analysing fish biomass, biodiversity, and changes after restoration measures. A total of 685 fish samples were examined across four periods, from 2011 to 2023. Biodiversity index, relative biomass, and non-native species were analysed to evaluate the restoration measures’ influence. All parameters showed a negative trend until the restoration works were implemented, after which they increased. This study also provides recommendations to improve the site considering the Mission Restore our Ocean and Waters by 2030.

Wetlands play a vital role in conserving waterbirds, particularly along major European river systems such as the Danube River and its tributaries. To promote the importance of wetlands and address the lack of data on bird biodiversity in aquatic ecosystems, this study was conducted to assess the baseline status of a demonstration site within the European project DaWetRest. The research focused on a lesser-studied pilot area, the Danube North of Kopački rit, near the village of Draž, located in the tri-border region of Croatia, Hungary, and Serbia. Systematic ornithological monitoring was carried out monthly from January to December 2024 across three monitoring areas (total transect length: 4200 m). A total of 26 bird taxa were recorded, comprising 2148 individual observations. The most dominant species were the Mallard (Anas platyrhynchos), Grey Heron (Ardea cinerea), and Great Cormorant (Phalacrocorax carbo). Conversely, the species that were the least present were White Stork (Ciconia ciconia), Squacco Heron (Ardeola ralloides), Great Crested Grebe (Podiceps cristatus), Eurasian Teal (Anas crecca), and Black Stork (Ciconia nigra). This study also examines the seasonal dynamics of waterbirds, providing essential baseline data for evaluating the effectiveness of upcoming restoration measures planned for the area.

Recent molecular analyses of the stone crayfish have revealed a high degree of genetic diversity. The greatest diversity is found in the western Balkans (Dinarides), where more than half of the known phylogroups exist in a relatively small geographical area, some of them having smaller distribution range than the others. While the Croatian and Slovenian parts of the Austropotamobius torrentium areal are well described, data from Bosnia and Herzegovina (BA) are lacking. Here we provide data from 13 different localities in the northwestern parts of BA. We analysed two mtDNA markers and the results revealed high genetic diversity with a total of 12 MT-COI and nine MT-16SrRNA haplotypes, with the majority of novel haplotypes. Both genes confirmed the presence of two known phylogroups and the discovery of a new group named VOJ. The CSE phylogroup was the most widespread and restricted to the Vrbas basin. The first detection of the BAN phylogroup in BA indicates its wider distribution and connects previously isolated findings from Croatia. The discovery of 18 unique haplotypes as well as a new phylogroup is of particular interest, but further studies are needed to clarify their exact relationship to other lineages.

Danube crayfish, one of the native European crayfish species, is on decline in many parts of its range. The Sava River and its tributaries are under increased pressure from invasive crayfish spreading. Providing data on resident native crayfish species is thus of utmost importance for their better conservation and protection. The population of Pontastacus leptodactylus (Eschscholtz, 1823) from a small tributary of the Sava River, The Matura River, has been investigated from May to August 2021. Our research encompassed a sample of 54 adult P. leptodactylus specimens (31 males and 23 females). Crayfish were sampled, measured and released unharmed. A standardized set of 12 morphometric parameters as well as body weight were taken. Positive correlation was found between body length and weight (♂ R2=0.9111; ♀ R2=0.9116), body weight and claws length (♂ R2=0.8923; ♀ R2=0.9596), as well as carapace width and body length (♂ R2=0.9761; ♀ R2=0.8838). Pronounced sexual dimorphism regarding most of the measured parameters was confirmed. Fulton's condition factor and the Crayfish constant both indicate males are in better fitness, which is in line with the results of previous research in Europe. Apart from crayfish data, the main physical and chemical parameters of the habitat and present aquatic macroinvertebrates community were measured as complementary data. Moderate level of organic pollution is present, with N and P (nitrogen and phosphorus) being the main threats, mostly due to intensive agriculture in the area. The macroinvertebrates community consists of 14 identified taxa, with gastropods as the most diverse and abundant group (57%). Crustaceans (Amphipoda and Isopoda) are the subdominant group in terms of relative abundance (30%). The recorded macroinvertebrate community indicates moderate organic pollution, and it is quite typical for similar watercourses in the region.

Ichthyological research conducted in 2019 on the Serbian part of the lower reaches of the Danube, downstream of the "Đerdap 2" dam, at two sampling sites, indicates the presence of 33 species of fish. At the examined localities, 51.5% of the ichthyofauna is under protection, and the community is 75.8% autochthonous. The indices of diversity indicated the more diverse and uniform community at the Radujevac site than the ušće Timok site. Saprobity in both localities was of b-mesosaprobic character, water quality class II was determined. The ecological characterization of the researched localities based on the composition of the community points to communities of the potamon type (Radujevac) and communities of the lower ritron (ušće Timok).

Huchen or Danube salmon Hucho hucho (Linnaeus 1758) is one of the largest salmonid species in the world and the largest species native to the Danube basin in Europe. In Serbia, this species inhabits the Drina river system, as well as the upper reaches of the River Ibar. It has already been introduced into the rivers Moravica and Đetinja, which are part of the Zapadna Morava catchment area. Most recently, huchen was stocked from its native habitat into the rivers Jerma and Nišava in the Južna Morava river system, and into the River Mlava which flows into the Danube. Huchen is listed as an endangered (EN) species on the IUCN Red List of Threatened Species and is protected in Serbia, and a Conservation Action Plan has already been adopted. In this report, we present the first record of this species in the River Grza, which is a part of the Velika Morava river system, outside its native range. The ichthyofauna of this recipient river consists of brown trout Salmo trutta L. and Eurasian minnow Phoxinus phoxinus L. In a small river of a fragile ecosystem such as this, the introduction of huchen as an apex predator can seriously harm the species of the native fish community, which warns of the illegal stocking measures currently in process.

The aim of this study was to assess the frequency of spicule malformations in freshwater sponges in relation to selected environmental parameters of the streams and the presence of river pollutants. A total of 50 sponge samples were collected from ten rivers in Serbia. Selected parameters of the water varied considerably at every site where sponges were found. After spicule preparation, the samples were subjected to morphological analysis by light and scanning electron microscopy, and the number of anomalies were recorded (spicules with bulbous enlargements, sharply bent, bifurcated, scissor- and cross-like, and t-shaped). The frequencies and types of malformations within the analyzed specimens varied from 1 to 100 per 1000 spicules, with an average number of 12 per 1000. The main types of anomalies were single- and double-bent spicules. The highest number of anomalies was found in a specimen of Eunapius fragilis collected at Markovac (Velika Morava River), and the lowest number was found in a specimen of Ephydatia fluviatilis from Kanjiža (Tisa River). The sites with the lowest and the highest numbers of anomalies showed statistically significant differences in concentrations of ammonia, orthophosphates, sodium, chloride, manganese, and lead. This study indicates that several pollutants potentially affect the occurrence of spicule anomalies.

Twenty-three morphometric characteristics of spiny-cheek crayfish Faxonus limosus from Danube, Serbia, were analyzed to describe the general body shape. Forty-eight specimens were caught in May 2022 and January 2023 and measured for morphometric variation. Also, the values of two crayfish condition indices, Fulton?s condition factor (FCF) and crayfish constant (CC), were determined. Most of the analyzed characteristics were moderately variable (CV 10-30%). Principal component analysis (PCA) was applied to the morphological measurements. All the variables make similar contributions to the variance of the first principal component. The highest contributions are from variables CEF and ARL.ARW, CPH, ABH, CPW, and ROW significantly contributed to the second principal component variance. The population of spiny-cheek crayfish at the investigated site has a relatively stable age structure.

Over the last 14 years, ichthyological and ecological parameters have been monitored in the Labudovo okno Ramsar site. This area is important for its biodiversity as it is home to many rare and endangered plants and animal species. A total of 3861 fish specimens were sampled and measured at six sampling sites four times during the sampling period. An analysis of biodiversity indexes, relative biomass (kg/ha), and relative annual production (kg/ha) was carried out to assess the effectiveness of existing conservation measures. The results obtained show a trend decline in biodiversity, relative biomass, and relative annual production. This indicates a biodiversity conservation problem that should be addressed through other mechanisms in addition to the principles of the Ramsar Convention.

This sighting record of marbled polecat Vormela peregusna is the westernmost for this globally vulnerable (VU) carnivore out of the native distribution range and the first one for Bosnia and Herzegovina. The current national conservational status is unknown. Hence, this species should be data deficient (DD) in the national legislative.

A pool of data already existing about D-loop, i.e., the Control Region (CR) haplotypes of the mitochondrial DNA (mtDNA) of brown trout, Salmo trutta Linnaeus, 1758, tentative Adriatic trout Salmo farioides Karaman, 1938, and tentative Macedonian trout, Salmo macedonicus (Karaman, 1924), and their reconstructed phylogeography makes a good starting point for resolving their evolutionary history. That includes the dating of particular events in it. The events have hitherto been dated using the method of a molecular clock. Various calibrations were applied for the mutation rate, owing to the incongruence between the time of divergence that various authors notified and general knowledge about events in geological history and the periods in which they occurred in the Mediterranean region. Since geological history events were mandatory for setting the scene for the evolutionary history of brown trout, the incongruence between them has questioned the molecular clock calibration’s validity. From results about both the phylogeography and phylogenetic relations between native haplotypes (both partial and whole CR sequences) and the population genetics that characterized particular populations, we calculated the time of divergence between haplotypes in the regions of the western part of the Balkans: Iron Gate broader area in eastern Serbia, continental Montenegro and south-eastern Serbia. The distinct status of adjacent populations was verified by frequencies of microsatellites’ alleles and the STRUCTURE analysis that examined the significance of differences between them. In particular, we examined the populations that were clearly separated either by physical barriers, such as a waterfall in eastern Serbia (e.g., the upper and lower River Rečka supplemented by nearby rivers Vratna and Zamna), or by underground drops in Montenegro (e.g., upper and lower River Zeta, and rivers Nožica and lower River Mrtvica as isolated counterparts). We used the so far most common substitution rate of 1% in a million years’ (MY) period. The divergence times we obtained were compared to the events known for the region from available geological history data. There was a fairly good congruence between the dating obtained by the molecular clock method and that by geological history where the advanced, i.e., modern haplotypes, were concerned. In contrast, the congruence was worse for dating of divergence when more ancient haplotypes were in question, being much better if the mutational rate would be decreased to lower rates. That supported results both from the Rate Correlation Test about the independence of evolutionary rates in different lineages of brown trout, and from the Molecular Clock Test, which revealed that the evolutionary rate throughout the phylogenetic tree is not equal. That implies a difference in the speed of evolution in them, which was likely slower and faster, in the ancient, pre-Pleistocene haplotypes and the advanced, Pleistocene ones, respectively. The setting of the variable, or non-linear (i.e., logarithmic) speed of evolving seems helpful, since the early cladogenesis with the dominance of mutations was most likely combined afterwards with the acting of other evolutionary mechanisms, especially of genetic drift in populations that passed through the bottleneck episodes of the abrupt decrease in population size during the unfavourable periods of their evolutionary history.

This paper provides an overview of the qualitative composition and structure of the microcrustacean of the Grliško reservoir based on field research conducted from 11 June 2019 to 9 July 2019. Sampling was carried out every seven days at sub-sites with different macrofauna, using the standard hydrobiological methodology. A total of 18 zooplankton taxa were recorded, belonging to the following groups: Rotifera (1 taxon), Cladocera (12 taxa), and Copepoda (5 taxa). The largest number of taxa was found in June. The total number of taxa was almost the same in the sub-areas with a lot of macrovegetation and without vegetation but differed in the qualitative composition of zooplankton species, spatially and temporally. Since the main purpose of the Grliško reservoir is to provide water for the population, it is necessary to constantly monitor the zooplankton, as it can be an important indicator of the state of this aquatic ecosystem.

Understanding the development of adaptation studies and the restrictions, requirements, and possibilities of literature-to-film adaptations enables an effective engagement with adaptations of narrative literature into film.An overview of the disparate approaches to defining adaptations, of Robert Stam's reevaluation of adaptations on the basis of 'intertextual dialogism', and of Linda Hutcheon's layered understanding of adaptations as processes and products sets up the essential framework for understanding text-to-screen adaptations.The demands for transfer and adaptation proper within adaptations of literary texts to films, and the similarities and differences between cinematic and literary codes complement the essential framework for effectively evaluating text-to-screen adaptations.

Brown trout is a common type of fish grown for consumption in open and flowing fish ponds on the rivers of Bosnia and Herzegovina. We conducted this study during three seasons (spring, summer and autumn) to obtain a complete picture of the morphological and histological characteristics of selected trout tissues. The physicochemical characteristics of the water from the Pliva River near Pljeva and the fish pond where intensive breeding of trout is carried out were analyzed. These analyses have shown that there are no major deviations in water quality and that the water in the pond is of excellent quality. A total of 90 trout were harvested during all three seasons and their morphometric characteristics were determined by analyzing ten parameters. After the dissection of all individuals, histological and stereological analysis was performed to compare the tissues of the liver, stomach, gills and muscles. These analyses showed significant differences in the histoarchitecture of selected trout tissues from the pond compared to the river. Liver tissue had altered hepatocyte shape and presence of adipocytes; stomach tissue had stronger mucosa and weaker muscle layer; gill tissue had lower respiratory lamellae; while muscle tissue had a significant presence of adipose tissue in brown trout living in the fish pond compared to those in the river. All these changes are due to the quality of commercial feed and the inability to move freely.

Salmonids are an extensively hatchery-reared group of fishes that have been introduced worldwide mainly for their high commercial and recreational value. The Balkan Peninsula (south-eastern Europe) is characterised by an outstanding salmonid diversity that has become threatened by the introduction of non-native salmonids whose potential risk of invasiveness in the region remains unknown and especially so under predicted climate change conditions. In this study, 13 extant and four horizon non-native salmonid species were screened for their risk of invasiveness in the Danube and Adriatic basins of four Balkan countries. Overall, six (35%) of the screened species were ranked as carrying a high risk of invasiveness under current climate conditions, whereas under predicted conditions of global warming, this number decreased to three (17%). Under current climate conditions, the very high risk (‘top invasive’) species were rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta (sensu stricto), whereas under predicted climate change, this was true only of O. mykiss. A high risk was also attributed to horizon vendace Coregonus albula and lake charr Salvelinus namaycush, and to extant Atlantic salmon Salmo salar and brook trout Salvelinus fontinalis, whose risk of invasiveness, except for S. fontinalis, decreased to medium. For the other eleven medium-risk species, the risk score decreased under predicted climate change, but still remained medium. The outcomes of this study reveal that global warming will influence salmonids and that only species with wider temperature tolerance, such as O. mykiss will likely prevail. It is anticipated that the present results may contribute to the implementation of appropriate management plans to prevent the introduction and translocation of non-native salmonids across the Balkan Peninsula. Additionally, adequate measures should be developed for aquaculture facilities to prevent escapees of non-native salmonids with a high risk of invasiveness, especially into recipient areas of high conservation value.