Search

The sediment succession of Lake Emanda in the Yana Highlands was investigated to reconstruct the regional late Quaternary climate and environmental history. Hydro‐acoustic data obtained during a field campaign in 2017 show laminated sediments in the north‐western and deepest (up to ̃15 m) part of the lake, where a ̃6‐m‐long sediment core (Co1412) was retrieved. The sediment core was studied with a multi‐proxy approach including sedimentological and geochemical analyses. The chronology of Co1412 is based on 14C AMS dating on plant fragments from the upper 4.65 m and by extrapolation suggests a basal age of c. 57 cal. ka BP. Pronounced changes in the proxy data indicate that early Marine Isotope Stage (MIS) 3 was characterized by unstable environmental conditions associated with short‐term temperature and/or precipitation variations. This interval was followed by progressively colder and likely drier conditions during mid‐MIS 3. A lake‐level decline between 32.0 and 19.1 cal. ka BP was presumably related to increased continentality and dry conditions peaking during the Last Glacial Maximum (LGM). A subsequent rise in lake level could accordingly have been the result of increased rainfall, probably in combination with seasonally high meltwater input. A milder or wetter Lateglacial climate increased lake productivity and vegetation growth, the latter stabilizing the catchment and reducing clastic input into the lake. The Bølling‐Allerød warming, Younger Dryas cooling and Holocene Thermal Maximum (HTM) are indicated by distinct changes in the environment around Lake Emanda. Unstable, but similar‐to‐present‐day climatic and environmental conditions have persisted since c. 5 cal. ka BP. The results emphasize the highly continental setting of the study site and therefore suggest that the climate at Lake Emanda was predominantly controlled by changes in summer insolation, global sea level, and the extent of ice sheets over Eurasia, which influenced atmospheric circulation pa

During the last glacial–interglacial cycle, Arctic biotas experienced substantial climatic changes, yet the nature, extent and rate of their responses are not fully understood1–8. Here we report a large-scale environmental DNA metagenomic study of ancient plant and mammal communities, analysing 535 permafrost and lake sediment samples from across the Arctic spanning the past 50,000 years. Furthermore, we present 1,541 contemporary plant genome assemblies that were generated as reference sequences. Our study provides several insights into the long-term dynamics of the Arctic biota at the circumpolar and regional scales. Our key findings include: (1) a relatively homogeneous steppe–tundra flora dominated the Arctic during the Last Glacial Maximum, followed by regional divergence of vegetation during the Holocene epoch; (2) certain grazing animals consistently co-occurred in space and time; (3) humans appear to have been a minor factor in driving animal distributions; (4) higher effective precipitation, as well as an increase in the proportion of wetland plants, show negative effects on animal diversity; (5) the persistence of the steppe–tundra vegetation in northern Siberia enabled the late survival of several now-extinct megafauna species, including the woolly mammoth until 3.9 ± 0.2 thousand years ago (ka) and the woolly rhinoceros until 9.8 ± 0.2 ka; and (6) phylogenetic analysis of mammoth environmental DNA reveals a previously unsampled mitochondrial lineage. Our findings highlight the power of ancient environmental metagenomics analyses to advance understanding of population histories and long-term ecological dynamics.

The late Quaternary climatic and environmental history of the Severnaya Zemlya Archipelago in the Russian High Arctic has been the focus of many palaeoenvironmental studies since the 1970s. However, the existing data are highly fragmentary and sometimes contradictory. New information concerning the archipelago's environmental history was derived from a 2.46-m-long sediment core from Lake Tvyordoe, located in the northwestern part of Bolshevik Island. The core was investigated by a multi-proxy approach that comprises radiocarbon dating as well as lithological, granulometrical, palynological and geochemical analyses. The results provide new insights into the vegetation history as well as changes in lake level, lake-ice cover, and water and sediment input since the Last Glacial Maximum (LGM). Fine-grained, laminated sediments at the core base, which were dated to c. 24.2 cal. ka BP, suggest lacustrine sedimentation under a permanent ice cover with low meltwater supply. This, along with a lack of glacial and glacial-lacustrine deposits, supports earlier assumptions that Bolshevik Island was not covered by the Barents-Kara Ice Sheet during the LGM. Furthermore, even the Mushketov Ice Cap, the closest ice mass to Lake Tvyordoe, did not expand from the denudation plateau to the lake. During the terminal Pleistocene, starting c. 14.5 cal. ka BP, warmer and wetter climate conditions resulted in higher sediment loads. The most favourable environmental conditions prevailed on Bolshevik Island throughout the Early and Middle Holocene (c. 11.7-6.5 cal. ka BP), when low shrub tundra associations with dwarf birch, willow and alder dominated the vegetation. After c. 10.0 cal. ka BP, a shift to climate drying occurred, which, after 6.5 cal. ka BP, was accompanied by a climate cooling. The Late Holocene climate, according to pollen data (suggesting sparse lichen-moss-grass cover) and relatively low total organic carbon (TOC) contents, was rather similar to that during the Lateglacial

The new pollen record from the upper 12.75m of a sediment core obtained in Lake Ladoga documents regional vegetation and climate changes in northwestern Russia over the last 13.9cal. ka. The Lateglacial chronostratigraphy is based on varve chronology, while the Holocene stratigraphy is based on AMS C-14 and OSL dates, supported by comparison with regional pollen records. During the Lateglacial (c.13.9-11.2cal. ka BP), the Lake Ladoga region experienced several climatic fluctuations as reflected in vegetation changes. Shrub and grass communities dominated between c.13.9 and 13.2cal. ka BP. The increase in Picea pollen at c.13.2cal. ka BPprobably reflects the appearance of spruce in the southern Ladoga region at the beginning of the AllerOd interstadial. After c.12.6cal. ka BP, the Younger Dryas cooling caused a significant decrease in spruce and increase in Artemisia with other herbs, indicative of tundra- and steppe-like vegetation. A sharp transition from tundra-steppe habitats to sparse birch forests characterizes the onset of Holocene warming c.11.2cal. ka BP. Pine forests dominated in the region from c.9.0 to 8.1cal. ka BP. The most favourable climatic conditions for deciduous broad-leaved taxa existed between c.8.1 and 5.5cal. ka BP. Alder experiences an abrupt increase in the local vegetation c.7.8cal. ka BP. The decrease in tree pollen taxa (especially Picea) and the increase in herbs (mainly Poaceae) probably reflect human activity during the last 2.2cal. ka. Pine forests have dominated the region since that time. Secale and other Cerealia pollen as well as ruderal herbs are permanently recorded since c. 0.8cal. ka BP.

Lake Ladoga hosts preglacial sediments, although the Eurasian ice sheet overrode the area during the LGM. These sediments were first discovered by a seismic survey and are investigated using a 22.75-m-long core. Its upper 13.30m comprise Holocene and Lateglacial sediments separated from the lower 11.45m of preglacial sediments by a hiatus. They consist of highly terrigenous lacustrine sediments, which according to OSL dating, were deposited during an early stage of the last ice age (MIS 5). The palynological data allow a first reconstruction of the Early Weichselian environmental history for northwestern Russia. Birch and alder forests with broad-leaved taxa dominated during MIS 5d (c.118-113 ka), suggesting a climate more favourable than in the Holocene. A high content of well-sorted sands and poorly preserved palynomorphs indicates a shallow-water environment at least temporarily. More fine-grained sediments and better preserved organic remains suggest deeper water environments at the core location during MIS 5c (c.113-88 ka). Pine and spruce became dominant, while broad-leaved taxa started to disappear, especially after c.90 ka, pointing to a gradual climate cooling. An increase in open herb-dominated habitats at the beginning of MIS 5b (c.88-86 ka) reflects a colder and dryer climate. However, later (c.86-82 ka) pine and spruce again became more common. Birch and alder forests dominated in the area c.82-80 ka (beginning of MIS 5a). Although open treeless habitats also became more common at this time, a slight increase in hazel may point to somewhat warmer climate conditions coinciding with the beginning of MIS 5a. The studied sediments also contain numerous remains of freshwater algae and cysts of marine and brackish-water dinoflagellates and acritarchs documenting that the present lake basin was part of a brackish-water basin during the Early Weichselian, probably as a gulf of the Pre-Baltic Sea.

Lake El'gygytgyn, located in central Chukotka, Russian Arctic, was the subject of an international drilling project that resulted in the recovery of the longest continuous palaeoclimatic and palaeoenvironmental record for the terrestrial Arctic covering the last 3.6 million years. Here, we present the reconstruction of the lake-level fluctuations of Lake El'gygytgyn since Marine Isotope Stage (MIS) 7 based on lithological and palynological as well as chronological studies of shallow-water sediment cores and subaerial lake terraces. Reconstructed lake levels show an abrupt rise during glacial-interglacial terminations (MIS 6/5 and MIS 2/1) and during the MIS 4/3 stadial-interstadial transition. The most prominent lowstands occurred during glacial periods associated with a permanent lake-ice cover (namely MIS 6, MIS 4 and MIS 2). Major triggering mechanisms of the lake-level fluctuations at Lake El'gygytgyn are predominantly changes in air temperature and precipitation. Regional summer temperatures control the volume of meltwater supply as well as the duration of the lake-ice cover (permanent or seasonal). The duration of the lake-ice cover, in turn, enables or hampers near-shore sediment transport, thus leading to long-term lake-level oscillations on glacial-interglacial time scales by blocking or opening the lake outflow, respectively. During periods of seasonal ice cover the lake level was additionally influenced by changes in precipitation. The discovered mechanism of climatologically driven level fluctuations of Lake El'gygytgyn are probably valid for large hydrologically open lakes in the Arctic in general, thus helping to understand arctic palaeohydrology and providing missing information for climate modelling.

Lake Ladoga in northwestern Russia is Europe's largest lake. The postglacial history of the Ladoga basin is for the first time documented continuously with high temporal resolution in the upper 13.3m of a sediment core (Co1309) from the northwestern part of the lake. We applied a multiproxy approach including radiographic imaging, (bio-)geochemical and granulometric analyses. Age control was established combining radiocarbon dating with varve chronology, the latter anchored to a correlated radiocarbon age from a lake close by. The age-depth model reveals the onset of glacial varve sedimentation at 13910 +/- 140cal. a BP, when Lake Ladoga was part of the Baltic Ice Lake. Linear extrapolation of published retreat rates of the Scandinavian Ice Sheet provides a formation age of the Luga moraine close to Lake Ladoga's southern shore of 14.5-15.9cal. ka BP, older than previously assumed. Varve sedimentation covers the BOlling/AllerOd interstadial, the Younger Dryas stadial and the Early Holocene. Varve-thickness variations, conjoined with grain-size and geochemical variations, inform about the relative position of the Scandinavian Ice Sheet and the climate during the deglaciation phase. The upper limit of the varved succession marks the change from glaciolacustrine to normal lacustrine sedimentation and post-dates the drainage of the Baltic Ice Lake as well as the formation of the Salpausselka II moraine north of Lake Ladoga, by c.250years. The Holocene sediment record is divided into three periods in the following order: (i) a lower transition zone between the Holocene boundary and c.9.5cal. ka BP, characterized by mostly massive sediments with low organic content, (ii) a phase with increased organic content from c.9.5 to 4.5cal. ka BP corresponding to the Holocene Thermal Maximum, and (iii) a phase with relatively stable sedimentation in a lacustrine environment from c.4.5cal. ka BP until present.

A multi-channel, high-resolution seismic reflection survey using a Micro-GI airgun was carried out in the framework of the Russian-German project PLOT (Paleolimnological Transect) on Lake Levinson-Lessing, Taymyr Peninsula, in 2016. In total, similar to 70km of seismic reflection profiles revealed in unprecedented detail the glacial and postglacial sedimentary infill of the lake basin. Five main seismic units have been recognized and interpreted as glacial (Unit V), subglacial and proglacial (Unit IV), marine (Unit III), fluvial-lacustrine (Unit II) and lacustrine (Unit I) sediments. Of particular significance are imbricated, south-orientated structures present in the southernmost part of the lake basin within Unit V and a large topographic ridge recognized in front of those structures. We interpret these structures as push moraines and an end moraine, respectively, left by the glacier after its retreat. The depositional pattern of the units above the moraines documents past lake-level fluctuations. We interpret Unit IV, Unit III and Unit I as highstand deposits, and Unit II as lowstand deposits. Gas-charged sediments dominate the northern part of the lake basin, whilst they occur only sporadically and in limited spatial extent in the central and southern parts of the lake. In the latter areas, the seismic and echo-sounder data suggest recent tectonic activity. Our study contributes to the reconstruction of environmental conditions in the Taymyr Peninsula directly following the Early Weichselian deglaciation and shows that deep tectonic lake basins affected by several glaciations can preserve important palaeoenvironmental records, which contributes significantly to our understanding of palaeoenvironmental changes in the Taymyr Peninsula and the central Russian Arctic.

Lake Ladoga hosts preglacial sediments, although the Eurasian ice sheet overrode the area during the LGM . These sediments were first discovered by a seismic survey and are investigated using a 22.75‐m‐long core. Its upper 13.30 m comprise Holocene and Lateglacial sediments separated from the lower 11.45 m of preglacial sediments by a hiatus. They consist of highly terrigenous lacustrine sediments, which according to OSL dating, were deposited during an early stage of the last ice age (MIS 5). The palynological data allow a first reconstruction of the Early Weichselian environmental history for northwestern Russia. Birch and alder forests with broad‐leaved taxa dominated during MIS 5d (c . 118–113 ka), suggesting a climate more favourable than in the Holocene. A high content of well‐sorted sands and poorly preserved palynomorphs indicates a shallow‐water environment at least temporarily. More fine‐grained sediments and better preserved organic remains suggest deeper water environments at the core location during MIS 5c (c . 113–88 ka). Pine and spruce became dominant, while broad‐leaved taxa started to disappear, especially after c . 90 ka, pointing to a gradual climate cooling. An increase in open herb‐dominated habitats at the beginning of MIS 5b (c . 88–86 ka) reflects a colder and dryer climate. However, later (c . 86–82 ka) pine and spruce again became more common. Birch and alder forests dominated in the area c . 82–80 ka (beginning of MIS 5a). Although open treeless habitats also became more common at this time, a slight increase in hazel may point to somewhat warmer climate conditions coinciding with the beginning of MIS 5a. The studied sediments also contain numerous remains of freshwater algae and cysts of marine and brackish‐water dinoflagellates and acritarchs documenting that the present lake basin was part of a brackish‐water basin during the Early Weichselian, probably as a gulf of the Pre‐Baltic Sea.

Modern process studies of the hydrologic balance of Lake El'gygytgyn, central Chukotka, and the sediment income from the catchment were carried out during a field campaign in spring and summer 2003. Despite high uncertainties due to the limited data, the results provide important first estimates for better understanding the modern and past sedimentation processes in this basin. Formed ca. 3.6 million years ago as a result of a meteorite impact, the basin contains one of the longest paleoclimate records in the terrestrial Arctic. Fluvial activity is concentrated over the short snowmelt period (about 20 days in second part of June). Underground outflow plays a very important role in the water balance and predominates over surface outflow. The residence time of the lake water is estimated to be about 100 yr.

Late Quaternary sediments in a permafrost environment recovered from the Elgygytgyn Impact Crater were studied to determine regional palaeoenvironmental variability and infer past water-level changes of the crater lake. Stratigraphic analysis of a 5 m long permafrost core is based on various lithological (grain size, total organic carbon, magnetic susceptibility) and hydrochemical (oxygen isotope composition, major cation content) properties and pore ice content. The results show that alluvial sediments accumulated on top of cryogenically weathered volcanic rock. Changes in the hydrochemical properties reflect different stages of cryogenic weathering. The lithological characteristics mark the transition from an erosive site to a site with accumulation. This environmental change is linked to a relative lake level highstand at >13 000 yr BP, when a shoreline bar was formed leading to slope sedimentation. Lake level dropped by 4 m during the Holocene.

During the last glacial–interglacial cycle, Arctic biotas experienced substantial climatic changes, yet the nature, extent and rate of their responses are not fully understood1–8. Here we report a large-scale environmental DNA metagenomic study of ancient plant and mammal communities, analysing 535 permafrost and lake sediment samples from across the Arctic spanning the past 50,000 years. Furthermore, we present 1,541 contemporary plant genome assemblies that were generated as reference sequences. Our study provides several insights into the long-term dynamics of the Arctic biota at the circumpolar and regional scales. Our key findings include: (1) a relatively homogeneous steppe–tundra flora dominated the Arctic during the Last Glacial Maximum, followed by regional divergence of vegetation during the Holocene epoch; (2) certain grazing animals consistently co-occurred in space and time; (3) humans appear to have been a minor factor in driving animal distributions; (4) higher effective precipitation, as well as an increase in the proportion of wetland plants, show negative effects on animal diversity; (5) the persistence of the steppe–tundra vegetation in northern Siberia enabled the late survival of several now-extinct megafauna species, including the woolly mammoth until 3.9 ± 0.2 thousand years ago (ka) and the woolly rhinoceros until 9.8 ± 0.2 ka; and (6) phylogenetic analysis of mammoth environmental DNA reveals a previously unsampled mitochondrial lineage. Our findings highlight the power of ancient environmental metagenomics analyses to advance understanding of population histories and long-term ecological dynamics.