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Concept: Danube


Rescue excavations recovered a skeleton that resurrect the contemporary dramatic history of Austria in the 17th century as troops besieged Vienna in the second Osmanic-Habsburg war. Unique for Central Europe is the evidence of a completely preserved camel skeleton uncovered in a large refuse pit. The male individual of slender stature indicates a few but characteristic pathological changes revealing not a beast of burden but probably a valuable riding animal. Anatomical and morphometrical analyses suggest a hybrid confirmed by the ancient DNA analyses resulting in the presence of a dromedary in the maternal and a Bactrian camel in the paternal line.

Concepts: Slovakia, Germany, Austria, Hungary, Camelid, Danube, 17th century, Vienna


Coupled measurements of nitrate (NO3(-)), nitrogen (N), and oxygen (O) isotopic composition (δ(15)NNO3 and δ(18)ONO3) were used to investigate the sources and processes of N cycling, while the microbial source tracking (MST) method was used to identify microbiological pollution in the surface water of the Sava River Basin (SRB) in autumn in 2014 and 2015 during high and low water discharge. Atmospheric nitrate deposition or nitrate-containing fertilizers were found not to be significant sources of riverine nitrate in the SRB. The ranges of isotope values suggest that NO3(-) in the SRB derives from soil nitrification, sewage, and/or manure, which were further supported by MST analysis. Microbiological indicators show the existence of hotspots of fecal pollution in the SRB, which are human associated. Long-term observations indicate persistent fecal contamination at selected locations caused by continuous discharge of untreated wastewaters into the SRB.

Concepts: Bacteria, Water, Nitrogen, Hydrology, Isotope, Guano, Manure, Danube


The transition from hunting and gathering to farming involved profound cultural and technological changes. In Western and Central Europe, these changes occurred rapidly and synchronously after the arrival of early farmers of Anatolian origin [1-3], who largely replaced the local Mesolithic hunter-gatherers [1, 4-6]. Further east, in the Baltic region, the transition was gradual, with little or no genetic input from incoming farmers [7]. Here we use ancient DNA to investigate the relationship between hunter-gatherers and farmers in the Lower Danube basin, a geographically intermediate area that is characterized by a rapid Neolithic transition but also by the presence of archaeological evidence that points to cultural exchange, and thus possible admixture, between hunter-gatherers and farmers. We recovered four human paleogenomes (1.1× to 4.1× coverage) from Romania spanning a time transect between 8.8 thousand years ago (kya) and 5.4 kya and supplemented them with two Mesolithic genomes (1.7× and 5.3×) from Spain to provide further context on the genetic background of Mesolithic Europe. Our results show major Western hunter-gatherer (WHG) ancestry in a Romanian Eneolithic sample with a minor, but sizeable, contribution from Anatolian farmers, suggesting multiple admixture events between hunter-gatherers and farmers. Dietary stable-isotope analysis of this sample suggests a mixed terrestrial/aquatic diet. Our results provide support for complex interactions among hunter-gatherers and farmers in the Danube basin, demonstrating that in some regions, demic and cultural diffusion were not mutually exclusive, but merely the ends of a continuum for the process of Neolithization.

Concepts: Germany, Serbia, Neolithic, Hungary, Poland, Romania, Danube, Moldova


The Croatian part of the Danube River extends over 188 km and comprises 58 % of the country’s overall area used for commercial freshwater fishing. To date, the heavy metal contamination of fish in the Croatian part of the Danube has not been studied. The main purpose of this study was to determine heavy metal levels in muscle tissue of sampled fish species and to analyze the measured values according to feeding habits of particular groups. Lead ranged from 0.015 μg(-1) dry weight in planktivorous to 0.039 μg(-1) dry weight in herbivorous fish, cadmium from 0.013 μg(-1) dry weight in herbivorous to 0.018 μg(-1) dry weight in piscivorous fish, mercury from 0.191 μg(-1) dry weight in omnivorous to 0.441 μg(-1) dry weight in planktivorous fish and arsenic from 0.018 μg(-1) dry weight in planktivorous to 0.039 μg(-1) dry weight in omnivorous fish. Among the analyzed metals in muscle tissue of sampled fish, only mercury exceeded the maximal level (0.5 mg kg(-1)) permitted according to the national and EU regulations determining maximum levels for certain contaminants in foodstuffs, indicating a hazard for consumers of fish from the Danube River.

Concepts: River, Toxicology, Lead, Serbia, Heavy metal music, Heavy metal, Romania, Danube


SUMMARY Species introduced into new areas often show a reduction in parasite and genetic diversity associated to the limited number of founding individuals. In this study, we compared microsatellite and parasite diversity in both native (lower Danube) and introduced populations of 4 Ponto-Caspian gobies, including those (1) introduced from within the same river system (middle Danube; Neogobius kessleri and N. melanostomus), and (2) introduced from a different river system (River Vistula; N. fluviatilis and N. gymnotrachelus). Microsatellite data confirmed the lower Danube as a source population for gobies introduced into the middle Danube. Both native and introduced (same river system) populations of N. kessleri and N. melanostomus had comparable parasite species richness and microsatellite diversity, possibly due to multiple and/or continual migration/introduction of new individuals and the acquisition of local parasites. Reduced parasite species richness and microsatellite diversity were observed in introduced (different river system) populations in the Vistula. A low number of colonists found for N. fluviatilis and N. gymnotrachelus in the Vistula potentially resulted in reduced introduction of parasite species. Insufficient adaptation of the introduced host to local parasite fauna, together with introduction into an historically different drainage system, may also have contributed to the reduced parasite fauna.

Concepts: Biodiversity, Symbiosis, River, Rhine, Romania, Danube, Danube Delta


This study focuses on the issues related to the waste management in river ports in general and, particularly, in ports on the river Danube’s flow through Serbia. The ports of Apatin, Bezdan, Backa Palanka, Novi Sad, Belgrade, Smederevo, Veliko Gradiste, Prahovo and Kladovo were analyzed. The input data (number of watercrafts, passengers and crew members) were obtained from harbor authorities for the period 2005-2009. The quantities of solid waste generated on both cruise and cargo ships are considered in this article. As there is no strategy for waste treatment in the ports in Serbia, these data are extremely valuable for further design of equipment for waste treatment and collection. Trends in data were analyzed and regression models were used to predict the waste quantities in each port in next 3 years. The obtained trends could be utilized as the basis for the calculation of the equipment capacities for waste selection, collection, storage and treatment. The results presented in this study establish the need for an organized management system for this type of waste, as well as suggest where the terminals for collection, storage and treatment of solid waste from ships should be located.

Concepts: Serbia, Waste, Danube, Syrmia, Vojvodina, Novi Sad, Belgrade, Ba ka


Pikeperch (Sander lucioperca), European catfish (Silurus glanis), common carp (Cyprinus carpio), and gobies (Neogobius gymnotrachelus, Neogobius melanostomus) were collected from the Danube River (Belgrade section), and samples of liver, muscle, or whole-body composites (in the case of gobies) were analyzed for As, Cu, Fe, Hg, Mn, and Zn with inductively coupled plasma optical spectrometry to find out if there was a correlation between accumulation of these elements in predatory and prey species, as well as in pairs of species with overlapping diets. Concentrations of all analyzed elements were either higher (Cu, Fe, Mn, Zn) in liver than in muscle, or equal (As, Hg), except for Hg in carp, which was higher in muscle. Mercury concentration in liver and muscle of predators (catfish, pikeperch) was significantly (<10(-4)) higher than in prey fishes (carp and gobies). The results indicate that Hg concentration was biomagnified through the food chain. Concentrations of As, Fe, and Hg in carp liver and gobies whole-body composite were similar, but carp had significantly (<10(-4)) higher values of Zn and Cu in liver. The regression analysis and trendline equations indicate that the concentrations of all tested elements, except for As in liver, and Mn and Fe in muscle, were similar in predatory fish (pikeperch and catfish), on one hand, and in prey fish (carp and gobies), on the other hand. Distinctly high Zn concentration in carp is very common in this species due to its physiology. Concentrations of Hg and Zn were higher than the maximum acceptable concentration due to the high pollution level in this section of the Danube River, accordingly posing a risk for the human consumption of these fish species.

Concepts: Fish, Predation, Serbia, Aquaculture, Danube, Wels catfish, Belgrade, Sava


Studies of metal accumulation in fish are mainly focused on the muscle tissue, while the metal accumulation patterns in other tissues have been largely neglected. Muscle is not always a good indicator of the whole fish body contamination. Elemental accumulation in many fish tissues and organs and their potential use in monitoring programs have not received proper attention. In the present study, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn concentrations were assessed by inductively coupled plasma mass spectrometry (ICP-MS) in the following 14 tissues of the wels catfish (Silurus glanis) from the Danube River: muscle, gills, spleen, liver, kidneys, intestine, gizzard, heart, brain, gallbladder, swim bladder, vertebra, operculum, and gonads. A high level of differential elemental accumulation among the studied tissues was observed. The maximum overall metal accumulation was observed in the vertebra, followed by the kidneys and liver, with the metal pollution index (MPI) values of 0.26, 0.25, and 0.24, respectively. The minimum values were observed in the gallbladder, muscle, brain, and swim bladder, with MPI values of 0.03, 0.06, 0.07, and 0.09, respectively. Average metal concentrations in the fish muscle were below the maximum allowed concentrations for human consumption. The mean As, Cd, Pb, Cu, Fe, and Zn concentrations in the muscle were 0.028, 0.001, 0.001, 0.192, 3.966, and 3.969 μg/g wet weight, respectively. We believe that the presented findings could be of interest for the scientific community and freshwater ecosystem managers. There is a need for further research that would assess less studied tissues in different fish species.

Concepts: Fish, Urinary bladder, River, Organs, Catfish, Siluridae, Danube, Wels catfish


Few studies have systematically investigated differences in performance, morphology and parasitic load of invaders at different stages of an invasion. This study analyzed phenotype-environment correlations in a fish invasion from initial absence until establishment in the headwater reach of the second largest European river, the Danube. Here, the round goby (Neogobius melanostomus) formed 73% of the fish abundance and 58% of the fish biomass in rip-rap bank habitats after establishment. The time from invasion until establishment was only about two years, indicating rapid expansion. Founder populations from the invasion front were different from longer established round goby populations in demography, morphology, feeding behaviour, sex ratio and parasitic load, indicating that plasticity in these traits determines invasion success. Competitive ability was mostly dependent on growth/size-related traits rather than on fecundity. As revealed by stable isotope analyses, specimens at the invasion front had a higher trophic position in the food web and seem to benefit from lower food competition. Somatic performance seems to be more important than investment in reproduction during the early stages of the invasion process and upstream-directed range expansion is not caused by out-migrating weak or juvenile individuals that were forced to leave high density areas due to high competition. This mechanism might be true for downstream introductions via drift. Greater abundance and densities of acanthocephalan endoparasites were observed at the invasion front, which contradicts the expectation that invasion success is determined by lower parasitic pressure in newly invaded areas. Overall, the pronounced changes in fish and invertebrate communities with a dominance of alien species suggest invasional meltdown and a shift of the upper Danube River towards a novel ecosystem with species that have greater resistance to goby predation. This seems to contribute to overcoming biological resistance and improve rapidity of dispersal.

Concepts: Population, Ecology, Symbiosis, River, Romania, Danube, Danube Delta, Round goby


An intense debate concerning the nature and mode of Neolithic transition in Europe has long received much attention. Recent publications of paleogenetic analyses focusing on ancient European farmers from Central Europe or the Iberian Peninsula have greatly contributed to this debate, providing arguments in favor of major migrations accompanying European Neolithization and highlighting noticeable genetic differentiation between farmers associated with two archaeologically defined migration routes: the Danube valley and the Mediterranean Sea. The aim of the present study was to fill a gap with the first paleogenetic data of Neolithic settlers from a region (France) where the two great currents came into both direct and indirect contact with each other. To this end, we analyzed the Gurgy ‘Les Noisats’ group, an Early/Middle Neolithic necropolis in the southern part of the Paris Basin. Interestingly, the archaeological record from this region highlighted a clear cultural influence from the Danubian cultural sphere but also notes exchanges with the Mediterranean cultural area. To unravel the processes implied in these cultural exchanges, we analyzed 102 individuals and obtained the largest Neolithic mitochondrial gene pool so far (39 HVS-I mitochondrial sequences and haplogroups for 55 individuals) from a single archaeological site from the Early/Middle Neolithic period. Pairwise FST values, haplogroup frequencies and shared informative haplotypes were calculated and compared with ancient and modern European and Near Eastern populations. These descriptive analyses provided patterns resulting from different evolutionary scenarios; however, the archaeological data available for the region suggest that the Gurgy group was formed through equivalent genetic contributions of farmer descendants from the Danubian and Mediterranean Neolithization waves. However, these results, that would constitute the most ancient genetic evidence of admixture between farmers from both Central and Mediterranean migration routes in the European Neolithization debate, are subject to confirmation through appropriate model-based approaches.

Concepts: Mediterranean Sea, Iberian Peninsula, Europe, Spain, Turkey, Archaeology, Romania, Danube