Intraspecific structure of the Coregonus lavaretus complex in water bodies of Siberia: a case of postglacial allopatric origin of Yukagirian whitefish

The results of morphological and genetic analyses of forms/species of the Coregonus lavaretus pidschian (Gmelin, 1789) complex from the Indigirka and Kolyma river basins are presented in the context of there being recent postglacial speciation events. It has been found that the studied whitefishes belong to the sparsely rakered and low lateral-line forms and have previously been described as Coregonus lavaretus pidschian n. jucagiricus Drjagin (Berg), 1932. Based on these characters, this whitefish does not differ from most Arctic whitefish populations (in particular from Coregonus lavaretus glacialis Kirillov, 1972). Analysis of variability of the ND1 gene (mtDNA) showed that whitefishes from the Indigirka and Kolyma basins belong to a distant phylogenetic lineage, which is significantly different from all previously studied whitefish lineages from the Ob, Yenisei, Lena, Anadyr, and Amur river basins. Analysis of variability of the ITS1 fragment (nDNA) showed that all studied forms/species (from Ob River to Amur River basins), including C. l. pidschian n. jucagiricus, have a tandem arrangement of two identical nucleotide fragments and very similar nucleotide composition of the ITS1 region. Based on contemporary data, this phylogenetic lineage of the C. pidschian complex could be considered a young postglacial allopatric species.

Effect of Permafrost Thawing on Discharge of the Kolyma River, Northeastern Siberia

With permafrost warming, the observed discharge of the Kolyma River in northeastern Siberia decreased between 1930s and 2000; however, the underlying mechanism is not well understood. To understand the hydrological changes in the Kolyma River, it is important to analyze the long-term hydrometeorological features, along with the changes in the active layer thickness. A coupled hydrological and biogeochemical model was used to analyze the hydrological changes due to permafrost warming during 1979–2012, and the simulated results were validated with satellite-based products and in situ observational records. The increase in the active layer thickness by permafrost warming suppressed the summer discharge contrary to the increased summer precipitation. This suggests that the increased terrestrial water storage anomaly (TWSA) contributed to increased evapotranspiration, which likely reduced soil water stress to plants. As soil freeze–thaw processes in permafrost areas serve as factors of climate memory, we identified a two-year lag between precipitation and evapotranspiration via TWSA. The present results will expand our understanding of future Arctic changes and can be applied to Arctic adaptation measures.

Minimal Evidence of Permafrost Carbon in Siberia’s Kolyma River

New research finds that Arctic rivers currently transport limited permafrost-derived dissolved organic carbon, which has implications for understanding the region’s changing carbon cycle—and its potential to accelerate climate change.

Seasonal methane and carbon dioxide emissions from the coastal nearshore of the Kolyma river, Siberia.

<p>Arctic rivers deliver ≈11% of global river discharge into the Arctic Ocean, while this ocean represents only ≈1% of the global ocean volume. Ongoing climate warming across the Arctic, and specifically Siberia, has led to regional-scale changes in precipitation patterns, greater rates of permafrost thaw and active layer deepening, as well as enhanced riverbank and coastal erosion. Combined, these climatic and cryospheric perturbations have already resulted in increased freshwater discharge and changes to constituent loads (e.g. dissolved organic carbon - OC) supplied from land to the Arctic Ocean.</p><p>To date, the majority of studies examining terrestrial organic matter (OM) delivery to the Arctic Ocean have focused almost entirely on freshwater (riverine) or fully-marine environments and been conducted during late summer seasons – often due to logistical constraints. Despite this, an improved understanding of how OC is transformed, mineralised and released during transit through the highly reactive nearshore estuarine environment is critical for examining the fate and influence of terrestrial OM on the Arctic Ocean. Capturing seasonality over the open water period is also necessary to identify current OM fluxes to the ocean vs the atmosphere, and aid in constraining how future changes may modify them.</p><p>Here we focus upon carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) measurements collected during six repeated transects of the Kolyma River and nearshore zone (covering ~120 km) from 2019. Transects spanned almost the entirety of the riverine open water season (June to September). We use these results, in parallel with gas concentrations derived from prior studies, to develop and validate a simple box-model of gas emissions from the nearshore zone.</p><p>Observations and model‐derived output data reveal that more than 50% of the cumulative gross delivery of CH<sub>4</sub> and CO<sub>2</sub> to the coastal ocean occurred during the freshet period with dissolved CH<sub>4</sub> concentrations in surface water reaching 660 Nanomole per liter [nmol/l]. These results demonstrate the relevance of seasonal dynamics and its spatial variability which are needed in order to estimate greenhouse gas fluxes on an annual basis.</p><p>More accurate understanding of land-ocean carbon fluxes in the Arctic is therefore crucial to mitigate the effects of climate change and to support the decisions of policy makers.</p>

Geoinformation analysis of spatial location of flood susceptible settlements in Yakutia

The subject of this research is the structure and content of the developed by the author Geographic Information System (GIS) “Flood susceptible settlements in the territory of Sakha Republic (Yakutia)”. The object of this research is 128 floodable settlements included in the list of the established flood zones in the Sakha (Yakutia), their analytical processing and cartographic interpretation. The sources for the creation of GIS contain published sources, statistical data, passports of socioeconomic development of the municipalities, archival documents, and information provided by the departmental organizations. The author conducted different types of geoinformation analysis (analysis of the geography of settlements by river basins, dynamics of the number of floods in the settlements (for the period 1929 – 2017), density of floodable settlements) in ArcGIS. It is determined that most of the settlements susceptible to flood are located in the middle reach  the Lena River and along its major tributaries – Aldan, Amga, Olekma; in the northeast of Yakutia, floodable settlements are mainly located in the upper reaches of the rivers Yana, Indigirka, Alazeya, as well as in the lower and middle reaches of the Kolyma River and its tributaries. The author notes that in some settlements, the number of floods over the period from 1930 to 2017 amounted to 30-40. It is also indicated that highest density of the settlements susceptible to flood is observed in Central Yakutia in the places of the highest concentration of population in the republic. The developed GIS can be used for adopting recommendations to protection the settlements from flooding.

Geochemical composition of Holocene and Late Pleistocene ice wedges in the yedoma of Stanchikovsky Yar and near the Chersky town, Northern Yakutia

The subject of this research is the Late Pleistocene and Holocene ice wedges exposed near Chersky settlement, lower Kolyma River, and in the yedoma strata of the Stanchikovsky Yar on the Maly Anyuy River. In the yedoma of the Stanchikovsky Yar, multi-tiered syngenetic ice wedges were exposed at different levels – from 10 to 35 m above river level. Ice wedge in the lower tier was sampled in detail. In the yedoma strata near Chersky relatively small fragments of ice wedges up to 1.5 m wide and up to 2 m high were exposed. 1.5-2 km from Chersky within the lacusrtine-paludal depression Holocene ice wedges were exposed. Ice wedges in these three sections was sampled to clarify the geochemical conditions of their formation. It is shown that concentration of Na+, K+, Mg2+, Cl- and SO42- in Holocene and Late Pleistocene ice wedges is very low and mean values do not exceed 5 mg/L. The highest values were obtained for Ca2+, which corresponds to the predominance of this ion in the modern snow of Yakutia and indicates that ice wedges were formed mainly from melted snow. Rather high values of NO3-, reaching 14-27 mg/L, are quite likely due to the swampy environment within polygonal landscapes, where organic matter of both plant and animal origin is decomposed. For comparison, in the water of the Kolyma and Maly Anyu rivers, concentration of nitrates is quite low and does not exceed 0.3 mg/L.

INFLUENCE OF LARGE-SCALE ATMOSPHERIC PROCESSES ON SEASONAL RUNOFF OF LARGE SIBERIAN RIVERS

Based on daily runoff volumes of four large Siberian rivers (the Ob, Yenisei, Lena, and Kolyma) for 1936-2018, the regime and changes in the total annual and seasonal runoff are analyzed. High synchronous and asynchronous correlations between monthly river runoff and atmospheric circulation indices of hemispheric and regional scales are revealed. In recent decades, the total annual runoff and its variations have increased (the rate of increase is most pronounced for the Kolyma River). A change in water content within a year is heterogeneous: weak positive trends are characteristic of the spring flood runoff and the summer-autumn period, and a significant increase occurred in the winter months. High correlations with a 1-8-month shift made it possible to identify the most informative regions, the atmospheric circulation over which makes a certain contribution to the variance of river runoff.

Features of natural plant complexes restoration and land reclamation in the area of Ust-Srednekanskaya hydroelectric power plant on the Kolyma river

The low resistance of the landscapes of the North-East of Russia to anthropogenic influences is shown. The features of natural plant complexes restoration and land reclamation in the area of the Ust-Srednekanskaya hydroelectric power station are considered. In order to create conditions for the successful restoration of vegetation cover after the impact of anthropogenic factors, it is recommended to carry out measures for leveling the disturbed surface and terracing it. It is proposed to carry out artificial sowing of cereals, which are characterized by regular and abundant fruiting.