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This article reviews all available information on the species composition, current distribution, and origins of the neobiotic (non-indigenous and restoring the lost range) freshwater mollusks in Siberia. An extensive literary search has been carried out, and virtually all existing publications of recent decades on the findings of freshwater mollusk species new to Siberia were taken into account. We examined extensive malacological collections of some of Russia's and Kazakhstan's scientific organizations. The core of the examined material is our own observations and collections made in various parts of Siberia and adjacent areas. An annotated checklist of neobiotic species of mollusks reliably recorded in Siberia is presented, and probable mechanisms and "corridors" of infiltration of these species into the region are discussed. Most of the discovered snail species belong to a group popular among aquarists, and their source of introduction is obvious. Another large portion of species infiltrate into the region with the development of fish farming. A classification of species of neobiotic freshwater mollusks of Siberia was proposed and a forecast was made for changes in the Siberian freshwater malacofauna for the coming decades. In our opinion, at present it is possible to accept the newest stage in the genesis of the freshwater malacofauna of Siberia, occurring in conditions specific to the Anthropocene. [ABSTRACT FROM AUTHOR]

Since the end of the 19th century, the circumpolar fauna of freshwater Mollusca has not been reviewed despite the substantial increase of knowledge on this subject. A review of the freshwater mollusks of the Arctic based on an analysis of published data, own results and examination of museum collections is presented. 104 species of Mollusca have been registered, which constitutes less than 2% of the global diversity. The actual diversity of the Circumpolar freshwater molluscs may lie between 100 and 120 species. No endemic taxa are found in the Arctic. The most species-rich Arctic subregion is Siberia, whereas the North America maintains the poorest fauna. The aquatic malacofauna of Beringia is similar to that of North America, and Beringia as a biogeographic region constitutes a part of the Nearctic. The ways of formation of the Circumpolar malacofauna are discussed, with evaluation of dispersal, adaptation, and environmental filtering as the faunogenesis factors. The number of non-alien species in the Circumpolar freshwater malacofauna remains very low, and only one reliable occurrence of an alien species is known. Among the Arctic molluscs only three have a conservation status other than 'least concern' or 'data deficient', whereas most resident species are widespread and abundant. [ABSTRACT FROM AUTHOR]

Stream water chemistry were analyzed across Vatinsky Egan River Catchment (West Siberia). The objective of the study is to reveal the spatial and seasonal variations of the water quality and to assess the anthropogenic chemical inputs into the river system. Stream chemistry were monitored in 24 sampling sites for a period extended from January 2002 to December 2005. Spatial distribution of constituents in the Vatinsky Egan River basin indicated pollution from non-point sources associated with oil development. Data revealed that ion concentrations of river waters are usually negatively correlated with stream discharge. The major spatial variations of the hydrochemistry are related to the salinity. Chloride exhibited wide and high concentration range. A comparison with another rivers of West Siberia reveals that Vatinsky Egan River is the most saline and regional impacts further out in the watershed. The salinity of the river water increases substantially as it crosses Samotlor oil field. Many Cl− concentrations in the middle and lower parts of the catchment exceed the world average river values by one or more orders of magnitude. For 38% of sampling events, total petroleum hydrocarbons (TPH) concentrations were above the recommended water quality standards. [ABSTRACT FROM AUTHOR]

Unionidae is a species-rich family of large freshwater mussels with an almost worldwide distribution. In many regions of the world, these mussels are imperiled. Northern Asia, excluding the Far East, is an excellent example of a region with a sharply impoverished fauna of the Unionidae as recently thought with one native species. Since the end of the 19th century, two freshwater mussel species of the genus Unio (U. pictorum and U. tumidus) were repeatedly recorded in Siberia. In the course of this study, these finds are confirmed both morphologically and genetically, the number of known occurrences of these mussels in the waterbodies of Asiatic Russia and Kazakhstan has drastically increased, and the third species, globally endangered U. crassus , was found in the Ob' River basin. The unique U. tumidus haplotype discovered from the Upper Irtysh River basin is of probable relic origin, which may indicate the presence of a Pleistocene refugium there. Due to natural environmental changes during the last century, several genera of freshwater Mollusca that previously inhabited Western Siberia, but went completely extinct in the Pleistocene, have started to recover the North Asiatic part of their former ranges. The case of Unio is exceptional since the recovery of its lost range goes not exclusively with the humans' help but also involves the natural mechanisms of dispersal and range extension, and also because these mussels are disappearing in other parts of the world and are placed in the IUCN Red List of Threatened Species. [ABSTRACT FROM AUTHOR]

Water quality in the Agan River catchment (West Siberia, Russia) was assessed based on data obtained between 1993 and 2017 at 25 monitoring stations. The purpose of the research was to assess the impact of oil field development on the quality of surface waters. Monitoring stations were located in the oil fields characterized by various levels of impact, from "moderate" (number of wells < 0.5 per 1 km2) to "extreme" (number of wells > 1 per 1 km2). Comparisons with the thresholds indicated that metal (Ni, Hg Pb, Zn, Cu, Mn and Fe) concentrations exceeded the standard limits for fisheries in 10.8%, 14.5%, 22.3%, 24.7%, 54.7%, 88.6% and 99.2% of samples, respectively. The high contents of Mn, Fe and Cu can be generally regarded as the natural results of intensive leaching of elements from acid soils. The total petroleum hydrocarbons (TPH) value exceeds the threshold in 34.6% of samples. The water quality was estimated using the Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI). The water quality of the Agan River catchment was classified as "poor" and "marginal". The TPH values displayed a significant positive correlation with the density of wells and with the percentage of oil-contaminated lands. Positive correlations were found between Cl− and the density of wells, the frequency of accidents and the area of contaminated lands. Trends of pollution are sensitive to changes of accident rate. The decrease in accident rate for the last decade resulted in declines in TPH and Cl concentrations. [ABSTRACT FROM AUTHOR]