Search Results (13)

The round goby Neogobius melanostomus is a notoriously invasive fish originating from the Ponto-Caspian region that in recent decades has successfully spread across the globe. One of its primary impacts is direct predation; in addition, when entering new ecosystems, the round goby is likely to become a food resource for many higher native predators. However, little is known either about the indirect effects of predators on the round goby as prey or its feeding behaviour and activity. The non-consumptive effect of the presence of higher native predators presumably plays an important role in mitigating the impact of non-native round gobies as mesopredators on benthic invertebrate communities, especially when both higher- and mesopredators occupy the same habitat. We tested the food consumption probability and gut evacuation rates in round gobies in response to chemical signals from a higher predator, the European eel Anguilla anguilla. Gobies were placed individually in experimental arenas equipped with shelters and exposed to water from a tank in which (a) the higher predator had actively preyed on a heterospecific prey, earthworms Lumbricus sp. (the heterospecific treatment; HS); (b) the higher predator had fed on round gobies (the conspecific treatment; CS); or (c) the water was provided as a control treatment (C). To ensure exposure to the chemical stimuli, this study incorporated the application of skin extracts containing damaged-released alarm cues from the CS treatment; distilled water was used for the remaining treatments. No significant differences were observed in either the food consumption probability or gut evacuation rate in the tested treatments. Despite the lack of reaction to the chemical stimuli, round gobies did exhibit high evacuation rates (R = 0.2323 ± 0.011 h⁻¹; mean ± SE) in which complete gut clearance occurred within 16 h regardless of the applied treatment. This rapid food processing suggests high efficiency and great pressure on resources regardless of the presence or not of a higher predator. These findings hint at the boldness of round gobies, which did not exhibit any pronounced threat sensitivity. This would seem to suggest great efficiency in food processing and a potential competitive advantage over local native species when colonising new ecosystems, irrespective of the presence of native predators. Our study did not detect any non-consumptive effect attributable to the higher predator, given that the feeding activity of the invasive round goby was not altered. Full article

The recent distribution of the Ponto-Caspian calanoid copepod, Eurytemora velox, in Western and Eastern Europe has been well-documented; however, there are no studies on the genetic diversity of the recently discovered Western Siberian species population. To contribute towards filling this gap, genetic diversity and distribution were investigated for E. velox collected in the Urals and Western Siberia of the Russian Federation to compare with the European populations. In this study, 44 specimens were dissected for the morphological studies, and 22 specimens of E. velox from different geographical points were analyzed for mitochondrial cytochrome oxidase I (CO1), nuclear ITS1-ITS2 (nITS) and nuclear ribosomal RNA (18SrRNA) gene fragments. Analysis of the CO1 gene region showed that the studied populations from the Urals and Western Siberia differ significantly from European ones and represent a separate genetic line. However, the nuclear nITS and 18SrRNA genes, as well as the results of morphological analysis, did not show such isolation of the Trans-Ural populations from those in Europe. As in many studies on E. velox, we found atypical structural features of the fifth prosomal leg among females in the Ob Bay. Their share was 36% of the number of studied individuals. The CO1 shows that the divergence of genetic lines occurred approximately in the Middle Pleistocene, and the species itself is Paleogene–Neogene by origin. Based on these data, a different scenario of E. velox distribution or possible refuge survival is discussed. Full article

The duck mussel Anodonta anatina is widely distributed throughout the freshwater basins of Northern, Central, and Western Eurasia, and it has a comprehensive genetic structure. This study was devoted to the analysis of lineages, which are defined based on COI gene sequences. Our new dataset was expanded by samples from freshwater basins of Northern and Central Eurasia. It allowed us to reveal a high level of genetic diversity for the widely distributed trans-Eurasian lineage of A. anatina for the first time. As for results, representative samples from the Russian Plain, Southern Siberia, and the Ural region showed the presence of multiple interactions between duck mussel populations, indicating the existence of connections between freshwater basins in this region during the Late Quaternary. The genetic group from the freshwater basins of Northern Eurasia may be divided into two sub-lineages, which have differences in genetic structure and distribution patterns. It was revealed that there was a post-glacial expansion of duck mussels in the freshwater basins of Northern Eurasia after deglaciations of these territories and that the wide distribution of this species in this region was shaped via ancient connections between periglacial waterbodies. The lineage of A. anatina from the Ponto-Caspian region is a genetically rich and diverged group, which is present in the riverine basins of West-Central Asia related to the Caspian Sea. Full article

This article describes the results of a three-year study of invasive species of aquatic ecosystems in the vicinity of Ust-Luga, the largest Russian seaport in the Baltic. Taking into account the great importance of the participation of marine vessels in the dispersal of invasive species, an experimental study of the seasonality of accumulation of resting stages of aquatic invertebrates in the ballast compartments of a vessel located in the Baltic Sea of the Gulf of Finland was carried out. Experiments show that the time of filling the ballast compartments in late summer and autumn poses the greatest risk for the spread of aquatic invertebrates with ship ballast water. In the Baltic Russian port, 11 invasive species of zooplankton and zoobenthos were found, which comprises 15% of the biodiversity in the samples. Copepoda demonstrated the highest presence of invasive species in class among zooplankton groups (14%) and Malacostraca among benthos groups (80%). Alien species findings correspond to the main vectors of invasive species dispersal for the Baltic Sea: North America, Indochina, and the Ponto-Caspian region. Full article

Non-indigenous species may pose a threat to native ecosystems worldwide. In aquatic environments, invasives may have a negative impact on human food security and livelihoods. Several water fleas (Crustacea: Branchiopoda: Cladocera) are notorious invasive alien species influencing large freshwater lake systems and even inland seas. In the current review, we discuss the state of knowledge regarding non-indigenous species in the Cladocera and their invasiveness potential in different continents. We argue that the potential impacts and occurrence of cladoceran exotics may be higher than generally assumed. We critically review 79 cases from literature sources, involving 61 cladoceran taxa where records outside of their natural distribution ranges were previously interpreted as invasions. We assessed the probability of natural range expansions versus human-mediated introductions and we discuss several major corridors of invasion. We estimate human-mediated transportations for at least 43 taxa (out of 61; ca 70%), while other cases can be seen as natural expansions of their distribution ranges (not necessarily/not likely human-mediated) and/or taxonomical confusion. We confirm non-indigenous presence in recipient regions for at least 41 cladoceran taxa, of which several are true invasives (i.e., with negative impacts on native ecosystems). The majority are zooplankters with effects on pelagic freshwater ecosystems, yet we also report on introductions by littoral taxa. We argue that cryptic introductions of cladocerans are taking place on a global scale, yet they remain under the radar. We highlight several striking case studies, such as the Ponto–Caspian onychopods that have invaded the Baltic Sea and the Laurentian Great Lakes, and several clones of the anomopod genera Daphnia and Bosmina that have successfully colonised new environments, causing equilibria shifts in native aquatic worlds. At the same time, we dispel some myths about taxa that were misconstrued as invasive in certain localities. Based on our review, the first of its kind for freshwater zooplankton, future environmental monitoring tools including molecular techniques and detailed surveys with rigorous and critical taxonomical assessments may help to provide a clearer picture on the extent of invasiveness of cladocerans. Full article

The Dniester is one of the largest transboundary rivers of the Black Sea basin, and its lower reaches integrate the influence of climate change and hydropower plant (HPP) impact on the waterway. The decrease in precipitation and average annual air temperature increase and intensive hydroelectric construction have led to a decline in the total water content of the river, during the last 10 years, being below the long-term historical “norm”. The shifts in the river flow result in multidirectional seasonal dynamics of nutrient concentrations. During the modern period, a stabilization of nutrient concentrations takes place, being lower than at the peak of eutrophication in the 1970s–1980s, but higher than in the natural flow period. The construction of reservoirs leads to a long-term decline in silica concentrations, continuing in the modern period. The concentration of heavy metals and metalloids in water and bottom sediments of the river generally corresponds to the ecological status of “Moderate”. Biological communities show a high β-diversity of microalgae, but low diversity of plankton and benthic invertebrates. Biological communities respond to the impact of HPP in both the short- and long-term. Hydroelectric dams change the bioavailability of nutrients downstream which, in the long-term, causes shifts in phytoplankton composition, especially the reduction of Bacillariophyta due to the lack of silicates that are deposited in reservoirs. However, in the short-term, after the discharge from the HPP dam, the concentration of silicates and the proportion of diatoms increase. Long-term changes also include a decline in the proportion of Rotifera and an increase in Copepoda in the total abundance of zooplankton and the unification of the benthic community with an increase in the biomass of gastropods in the area, which can be considered as indicators of the impact of hydroelectric power plants. The saprobity index, calculated both for zooplankton and macrozoobenthos, characterised the water as moderately polluted; benthic biotic indexes (Biological monitoring working party (BMWP), Belgian Biotic Index (BBI), Danish Stream Fauna Index (DSFI)) calculated on macrozoobenthos described the condition as “low” quality. Full article

The Ponto-Caspian region is the main donor of invasive amphipods to freshwater ecosystems, with at least 13 species successfully established in European inland waters. Dikerogammarus spp. and Pontogammarus robustoides are among the most successful, due to their strong invasive impact on local biota. However, genomic knowledge about these invaders is scarce, while phylogeography and population genetics have been based on short fragments of mitochondrial markers or nuclear microsatellites. In this study, we provide: (i) a reconstruction of six mitogenomes for four invasive gammarids (D. villosus, D. haemobaphes, D. bispinosus, and P. robustoides); (ii) a comparison between the structure of the newly obtained mitogenomes and those from the literature; (iii) SNP calling rates for individual D. villosus and D. haemobaphes from different invasion sites across Europe; and (iv) the first time-calibrated full mitogenome phylogeny reconstruction of several Ponto-Caspian taxa. We found that, in comparison to other gammarids, the mitogenomes of Ponto-Caspian species show a translocation between the tRNA-E and tRNA-R positions. Phylogenetic reconstruction using the mitogenomes identified that Ponto-Caspian gammarids form a well-supported group that originated in the Miocene. Our study supports paraphyly in the family Gammaridae. These provided mitogenomes will serve as vital genetic resources for the development of new markers for PCR-based identification methods and demographic studies. Full article

This work aims to analyze the zoogeographic distribution of Calanoida in Kazakhstan. Kazakhstan belongs to the Palaearctic region, and its territory is ascribed to the European–Siberian and Nagorno–Asian biogeographical subregions. The European–Siberian subregion includes the Volga–Ural, Irtysh, and Turkestan–Aral provinces. The Balkhash province belongs to the Nagorno–Asian subregion. Studies of the Calanoida fauna were carried out between 1997 and 2019. For this purpose, 7250 zooplankton samples were taken in 130 different water bodies. Findings of 26 species of Calanoida have been documented. The richest in species composition (20) is the Calanoida fauna of the Irtysh province. Ten Calanoida species have been recorded in the Volga–Ural province, 8 in the Turkestan–Aral province, 7 in the Balkhash province, and 5 in the Ponto–Caspian region. The distribution of the species richness of the order is determined by a complex of climatic factors, including the density of the hydrographic network, a variety of hydrochemical conditions, and accidental acclimatization of species. Far Eastern species (Sinodiaptomus sarsi, Neutrodiaptomus incongruens, Neodiaptomus schmackeri) entered the inland water bodies of Kazakhstan, most likely through the introduction of non-native fish species. The Black Sea species Acartia tonsa and Calanipeda aquaedulcis were introduced into the Caspian Sea with ballast waters. Three autochthonous species (Limnocalanus macrurus, Eurytemora grimmi, Eurytemora minor), formerly inhabiting the Caspian Sea, can now be considered extinct. Acanthodiaptomus denticornis, Arctodiaptomus (R.) salinus, Phyllodiaptomus blanci, and Eudiaptomus graciloides are widespread in the region. Endemic species (Gigantodiaptomus irtyshensis, Arctodiaptomus naurzumensis) and species are new for Kazakhstan (Diaptomus (Chaetodiaptomus) mirus, Eudiaptomus transylvanicus, Arctodiaptomus dentifer, A. (Rh.) ulomskyi were found in small waterbodies; they are known only from single occurrence sites as well as Eurytemora caspica. The last one was described from the northern part of the Caspian Sea, in the coastal zone. Further research into small water bodies that are poorly studied may expand our knowledge of the diversity of Calanoida in Kazakhstan. Calanoida fauna of Kazakhstan was closest to the fauna of countries with a continental climate and most strongly differed from countries with subtropical and Mediterranean types of climates. Full article

For externally fertilising organisms in the aquatic environment, the abiotic fertilisation medium can be a strong selecting force. Among bony fishes, sperm are adapted to function in a narrow salinity range. A notable exception is the family Gobiidae, where several species reproduce across a wide salinity range. The family also contains several wide-spread invasive species. To better understand how these fishes tolerate such varying conditions, we measured sperm performance in relation to salinity from a freshwater and a brackish population within their ancestral Ponto-Caspian region of the round goby, Neogobius melanostomus. These two ancestral populations were then compared to nine additional invaded sites across northern Europe, both in terms of their sperm traits and by using genomic SNP markers. Our results show clear patterns of ancestral adaptations to freshwater and brackish salinities in their sperm performance. Population genomic analyses show that the ancestral ecotypes have generally established themselves in environments that fit their sperm adaptations. Sites close to ports with intense shipping show that both outbreeding and admixture can affect the sperm performance of a population in a given salinity. Rapid adaptation to local conditions is also supported at some sites. Historical and contemporary evolution in the traits of the round goby sperm cells is tightly linked to the population and seascape genomics as well as biogeographic processes in these invasive fishes. Since the risk of a population establishing in an area is related to the genotype by environment match, port connectivity and the ancestry of the round goby population can likely be useful for predicting the species spread. Full article

Common carp (Cyprinus carpio) is a widespread freshwater fish species of the Cyprinidae family, one of the largest and most diverse fish families. The natural habitats of C. carpio extend from Western Europe to South-East Asia. Common carp has remained an economically important fish species in aquaculture for many centuries and its production nowadays exceeds 4 million tons worldwide and continues to grow. The taxonomy of C. carpio is complicated, since this species is usually distinguished in two, three, and even four distinct subspecies. In the present study, we used ddRAD-sequencing to genotype 30 specimens from five wild common carp populations from the Ponto-Caspian, Balkhash-Ile, and Aral Sea geographical regions. It is demonstrated that they differ at the population level according to F-statistics analysis. At the same time, the subspecies status of C. carpio aralensis has not yet been confirmed. We found several loci that can be used as a discriminant for Aral and Ponto-Caspian wild common carp populations. It is suggested that Aral carp (C. carpio aralensis), which inhabits Balkhash-Ile and Aral Sea basins, is related to Ponto-Caspian or European carp (C. carpio carpio). Moreover, Aral carp might be the ancestor for European carp subspecies. Our results can be used to develop population-specific, high-density SNP marker panels, allowing the trade control of common carp production in the Eurasian Economic Union. Full article

Analysis of zoogeographic, paleogeographic, and molecular data has shown that the ancestors of many fresh- and brackish-water cold-tolerant hydrobionts of the Mediterranean region and the Danube River basin likely originated in East Asia or Central Asia. The fish genera Gasterosteus, Hucho, Oxynoemacheilus, Salmo, and Schizothorax are examples of these groups among vertebrates, and the genera Magnibursatus (Trematoda), Margaritifera, Potomida, Microcondylaea, Leguminaia, Unio (Mollusca), and Phagocata (Planaria), among invertebrates. There is reason to believe that their ancestors spread to Europe through the Paratethys (or the proto-Paratethys basin that preceded it), where intense speciation took place and new genera of aquatic organisms arose. Some of the forms that originated in the Paratethys colonized the Mediterranean, and overwhelming data indicate that representatives of the genera Salmo, Caspiomyzon, and Ecrobia migrated during the Miocene from the region of the modern Caspian through the Araks Strait, which existed at that time. From the Ponto-Caspian and the Mediterranean regions, noble salmon, three-spined stickleback, European pearl mussel, seals, and mollusks of the genus Ecrobia spread to the Atlantic Ocean and colonized the Subarctic and Arctic regions of Europe and North America. Our study indicates that the area of the former Paratethys retains its significance as a center of origin of new species and genera and that it has been the starting point of migration “corridors” up to the present time. Full article

Freshwater mussels (Bivalvia: Unionoida) play an important role in freshwater habitats as ecosystem engineers of the water environment. Duck mussel Anodonta anatina is widely distributed throughout Europe, Siberia, and Western and Central Asia, which makes it a convenient object for biogeographic studies. In this study, we analyzed the divergence of A. anatina populations and discovered a separate genetic lineage distributed in rivers of the Azov Sea basin. This was confirmed by the high genetic distances between this group and previously defined populations, and by the position of this clade in the Bayesian phylogeny calibrated by an external substitution rate. Based on our approximate Bayesian computation (ABC) analysis, biogeographic scenarios of A. anatina dispersal in Europe and Northern, Western, and Central Asia over the Neogene–Quaternary were simulated. The haplogroup’s isolation in the rivers of the Azov Sea basin most likely occurred in the Late Pliocene that was probably facilitated by rearrangement of freshwater basins boundaries in the Ponto-Caspian Region. Population genetic indices show the stability of this group, which allowed it to exist in the river basins of the region for a long time. The discovery of a long-term refugium in the rivers of the Azov Sea led to a better understanding of freshwater fauna evolution in the Neogene–Quaternary and highlighted the importance of conservation of these freshwater animals in the region as a source of unique genetic diversity. Full article

Hypanis colorata (Eichwald, 1829) (Cardiidae: Lymnocardiinae) is a bivalve relict species with a Ponto-Caspian distribution and is under strict protection in Romania, according to national regulations. While the species is depressed in the western Black Sea lagoons from Romania and Ukraine, it is also a successful invader in the middle Dniepr and Volga regions. Establishing a conservation strategy for this species or studying its invasion process requires knowledge about the genetic structure of the species populations. We have isolated and characterized nine polymorphic microsatellite markers in H. colorata. The number of alleles per locus ranged from 4 to 28 and the observed heterozygosity ranged from 0.613 to 1.000. The microsatellites developed in the present study are highly polymorphic and they should be useful for the assessment of genetic variation within this species. Full article