ALBERT

Description: Wildfires play an essential role in the ecology of boreal forests. In eastern Siberia, fire activity has been increasing in recent years, challenging the livelihoods of local communities. Intensifying fire regimes also increase disturbance pressure on the boreal forests, which currently protect the permafrost beneath from accelerated degradation. However, long-term relationships between changes in fire regime and forest structure remain largely unknown. We assess past fire-vegetation feedbacks using sedimentary proxy records from Lake Satagay, Central Yakutia, Siberia, covering the past c. 10,800 years. Results from macroscopic and microscopic charcoal analyses indicate high amounts of burnt biomass during the Early Holocene, and that the present-day, low-severity surface fire regime has been in place since c. 4,500 years before present. A pollen-based quantitative reconstruction of vegetation cover and a terrestrial plant record based on sedimentary ancient DNA metabarcoding suggest a pronounced shift in forest structure toward the Late Holocene. Whereas the Early Holocene was characterized by postglacial open larch-birch woodlands, forest structure changed toward the modern, mixed larch-dominated closed-canopy forest during the Mid-Holocene. We propose a potential relationship between open woodlands and high amounts of burnt biomass, as well as a mediating effect of dense larch forest on the climate-driven intensification of fire regimes. Considering the anticipated increase in forest disturbances (droughts, insect invasions, and wildfires), higher tree mortality may force the modern state of the forest to shift toward an open woodland state comparable to the Early Holocene. Such a shift in forest structure may result in a positive feedback on currently intensifying wildfires. These new long-term data improve our understanding of millennial-scale fire regime changes and their relationships to changes of vegetation in Central Yakutia, where the local population is already being confronted with intensifying wildfire seasons.

Description: Pronounced glacial and interglacial climate cycles characterized northern ecosystems during the Pleistocene. Our understanding of the resultant community transformations and past ecological interactions strongly depends on the taxa found in fossil assemblages. Here, we present a shotgun metagenomic analysis of sedimentary ancient DNA (sedaDNA) to infer past ecosystem-wide biotic composition (from viruses to megaherbivores) from the Middle and Late Pleistocene at the Batagay megaslump, East Siberia. The shotgun DNA records of past vegetation composition largely agree with pollen and plant metabarcoding data from the same samples. Interglacial ecosystems at Batagay attributed to Marine Isotope Stage (MIS) 17 and MIS 7 were characterized by forested vegetation (Pinus, Betula, Alnus) and open grassland. The microbial and fungal communities indicate strong activity related to soil decomposition, especially during MIS17. The local landscape likely featured more open, herb-dominated areas, and the vegetation mosaic supported birds and small omnivorous mammals. Parts of the area were intermittently/partially flooded as suggested by the presence of water-dependent taxa. During MIS 3, the sampled ecosystems are identified as cold-temperate, periodically flooded grassland. Diverse megafauna (Mammuthus, Equus, Coelodonta) coexisted with small mammals (rodents). The MIS 2 ecosystems existed under harsher conditions, as suggested by the presence of cold-adapted herbaceous taxa. Typical Pleistocene megafauna still inhabited the area. The new approach, in which shotgun sequencing is supported by metabarcoding and pollen data, enables the investigation of community composition changes across a broad range of taxonomic groups and inferences about trophic interactions and aspects of soil microbial ecology.

Description: Climate change is expected to cause major shifts in boreal forests which are in vast areas of Siberia dominated by two species of the deciduous needle tree larch (Larix). The species differ markedly in their ecosystem functions, thus shifts in their respective ranges are of global relevance. However, drivers of species distribution are not well understood, in part because paleoecological data at species level are lacking. This study tracks Larix species distribution in time and space using target enrichment on sedimentary ancient DNA extracts from eight lakes across Siberia. We discovered that Larix sibirica, presently dominating in western Siberia, likely migrated to its northern distribution area only in the Holocene at around 10,000 years before present (ka BP), and had a much wider eastern distribution around 33 ka BP. Samples dated to the Last Glacial Maximum (around 21 ka BP), consistently show genotypes of L. gmelinii. Our results suggest climate as a strong determinant of species distribution in Larix and provide temporal and spatial data for species projection in a changing climate.

Description: Alpine ecosystems on the Tibetan Plateau are being threatened by ongoing climate warming and intensified human activities. Ecological time-series obtained from sedimentary ancient DNA (sedaDNA) are essential for understanding past ecosystem and biodiversity dynamics on the Tibetan Plateau and their responses to climate change at a high taxonomic resolution. Hitherto only few but promising studies have been published on this topic. The potential and limitations of using sedaDNA on the Tibetan Plateau are not fully understood. Here, we (i) provide updated knowledge of and a brief introduction to the suitable archives, region-specific taphonomy, state-of-the-art methodologies, and research questions of sedaDNA on the Tibetan Plateau; (ii) review published and ongoing sedaDNA studies from the Tibetan Plateau; and (iii) give some recommendations for future sedaDNA study designs. Based on the current knowledge of taphonomy, we infer that deep glacial lakes with freshwater and high clay sediment input, such as those from the southern and southeastern Tibetan Plateau, may have a high potential for sedaDNA studies. Metabarcoding (for microorganisms and plants), metagenomics (for ecosystems), and hybridization capture (for prehistoric humans) are three primary sedaDNA approaches which have been successfully applied on the Tibetan Plateau, but their power is still limited by several technical issues, such as PCR bias and incompleteness of taxonomic reference databases. Setting up high-quality and open-access regional taxonomic reference databases for the Tibetan Plateau should be given priority in the future. To conclude, the archival, taphonomic, and methodological conditions of the Tibetan Plateau are favorable for performing sedaDNA studies. More research should be encouraged to address questions about long-term ecological dynamics at ecosystem scale and to bring the paleoecology of the Tibetan Plateau into a new era.

Description: This dataset comprises new data and previously published data on marine lipid biomarkers (brassicasterol, dinosterol, C37 alkenones, and the sum of them [∑PB]) in surface suspended particles at 334 stations from seven cruises between 2010 and 2015, and in surface sediments at 258 stations from eight cruises between 2006 and 2012 in the eastern China marginal seas (ECMS). Of all marine lipid biomarker data, 107 surface suspended particle samples were newly measured, with 227 surface suspended particle samples and 258 sediment samples previously published. We also provide the following oceanographic data, most of which were collected from published results (as described in the publication): sea surface temperature (SST, n = 273, from five cruises in summer of 2010–2015), salinity (n = 273, from five cruises in summer of 2010–2015), nutrient concentrations (dissolved inorganic nitrogen [DIN], dissolved inorganic phosphorus [DIP] and silicate [Si]) (n = 133, from three cruises in summer of 2011 and 2015) and Chl a (chlorophyll a, n = 229, from five cruises in summer of 2010–2014) in the surface water, as well as terrestrial biomarker [∑(C27 + C29 + C31) n-alkanes] contents (n = 226), TOC (total organic carbon content, n = 200), δ13CTOC (stable carbon isotope values for TOC, n=269), and sedimentation rate (n = 220) in surface sediments. Some data were measured using in situ CTD instrument in this study: sea surface temperature and salinity in the East China Sea in June 2010 and July 2013 (n = 54), and Chl a in the Changjiang River Estuary in August 2015 (n = 33). The contents of ∑(C27 + C29 + C31) n-alkanes in the southern Yellow Sea in April 2012 (n = 32) were also newly measured. The surface suspended particle samples were obtained by filtering on Whatman GF/F filters, and the surface sediments were collected by multiple corers or stainless-steel grab samplers. Marine and terrestrial lipid biomarkers were analyzed by gas chromatograph (Agilent 6890N) according to the method in Zhao et al. 2006 (doi: 10.1016/j.orggeochem.2005.08.022) and Wu et al. 2016 (doi: 10.1002/2015JG003167). The study resulting from this analysis has been published in Frontiers in Marine Science (doi:10.3389/fmars.2022.824181).

Description: 3D reflection seismic data were acquired using the P-Cable system of the National Oceanographic Centre, Southampton, UK during cruise 178 Leg 2 onboard RRS Charles Darwin between the 5th and 8th of April 2006. The responsible PI's was C. Berndt, Southampton Oceanography Centre, Southampton, UK. The aim of this cruise was to map submarine landslides on the eastern slopes of the Eivissa Channel, western Mediterranean Sea located between the islands of Ibiza-Formentera and the Spanish mainland. Berndt et al. (2012) used the acquired data to study repeated slope failure linked to fluid migration, while Lafuerza et al. (2012) studied geotechnical aspects of slope stability using this as additional data. Acquisition parameters: The source during seismic acquisition consisted of four 40 in3 Bolt 600B air guns spaced 0.75 m apart and tower at a depth of 1.5 m about 20 m behind the stern of the vessel (Berndt et al., 2012). The air guns are fitted with wave shape kits that emit approximately 10 in3 of air prior to the main volume to reduce the bubble pulse. The air pressure is 2000 psi, and the gun controller triggers the guns to figure every 7 seconds. The data were collected with 11 single-channel analogue streamers that were towed 10 m apart. The seismic cube in the Eivissa Channel covers an area of ca. 14 km2 (ca. 6.4 EW x 2.2 NS km) located at 306091.83 4280497.41; 305951.42 4278353.92; 312321.94 4277936.57 in UTM zone 31N. 3D seismic processing: Data were frequency filtered from 45 to 220 Hz and binned at 10 m bin interval before a Stolt time migration with a migration velocity of 1500 ms-1 was carried out. The resolution of the data is approximately 5-6 m vertically and for the 10 m inline and crossline spacing the horizontal resolution is 10-15 m (Berndt et al., 2012). Seismic data acquisition was performed between 10:05 PM on the 5th of April until 08:30 PM on the 7th of April 2006 (CD178 cruise report). The seismic cube is located at water depths of 550 to 825 m from east to west. Raw data is available here:doi:10.1594/PANGAEA.943523.

Description: 3D reflection seismic data were acquired using the P-Cable system of the National Oceanographic Centre, Southampton, UK during cruise 178 Leg 2 onboard RRS Charles Darwin between the 5th and 8th of April 2006. The responsible PI's was C. Berndt, Southampton Oceanography Centre, Southampton, UK. The aim of this cruise was to map submarine landslides on the eastern slopes of the Eivissa Channel, western Mediterranean Sea located between the islands of Ibiza-Formentera and the Spanish mainland. Berndt et al. (2012) used the acquired data to study repeated slope failure linked to fluid migration, while Lafuerza et al. (2012) studied geotechnical aspects of slope stability using this as additional data. Acquisition parameters: The source during seismic acquisition consisted of four 40 in3 Bolt 600B air guns spaced 0.75 m apart and tower at a depth of 1.5 m about 20 m behind the stern of the vessel (Berndt et al., 2012). The air guns are fitted with wave shape kits that emit approximately 10 in3 of air prior to the main volume to reduce the bubble pulse. The air pressure is 2000 psi, and the gun controller triggers the guns to figure every 7 seconds. The data were collected with 11 single-channel analogue streamers that were towed 10 m apart. The seismic cube in the Eivissa Channel covers an area of ca. 14 km2 (ca. 6.4 EW x 2.2 NS km) located at 306091.83 4280497.41; 305951.42 4278353.92; 312321.94 4277936.57 in UTM zone 31N. 2D seismic processing: During seismic processing of the 3D dataset significant ghost-artefacts were identified because some of the streamers were towed too deep. This required de-ghosting. Unfortunately, these attempts did not yield improved quality of the 3D seismic data. This was mainly because the 12.5 m streamers were too short for commonly used de-ghosting technique used in the industry. To increase vertical resolution individual 2D profiles were extracted from the raw dataset. Processing steps included frequency bandpass filtering, burst noise attenuation, binning, NMO-correction, stacked, and a Stolt migration with 1520 ms-1 was applied that resulted in higher resolution 2D profiles for 85 lines and 11 streamers (channels).

Description: This dataset contains the bulk sediment parameters (total organic carbon (TOC), carbon nitrogen ratio (C/N), δ13C), lipid biomarker (branched glycerol dialkyl glycerol tetraethers (brGDGTs), crenarchaeol, long-chain diols, long-chain n-alkanes, alkenones, sterols) and palynological (dinoflagellate cysts, pollen) content of 20 surface sediments (0-2 cm) from the northern Gulf of Mexico, near the Mississippi and Atchafalaya river mouths. Samples were retrieved from three land-sea transects; (1) offshore the Mississippi river, (2) offshore the Atchafalaya river and (3) on the 20 m isobar on the Louisiana shelf, during a research cruise in February 2020. Samples were analysed on their organic carbon composition, which was divided into soil-, fluvial- and plant-derived terrestrial organic carbon, and marine produced organic carbon, to investigate if the composition and quality of the terrestrial carbon had an influence on their dispersal patterns.

Description: The relative contribution and the composition of terrestrial organic matter were assessed by the analysis of phenolic lignin oxidation products and by the stable isotope composition of organic carbon in surface sediments of the Baltic Sea. For analyses, sub samples of lyophilized, ground and homogenized surface sediment (0-1 cm) material from the collection of surface sediments of the Institut fuer Ostseeforschung Warnemuende were used. Methods Lignin analysis: Between 500 to 2000 mg of dried and homogenised sediment were oxidized at 170°C for 2 h in the presence of 2 mol/L NaOH, CuO, and (NH)4Fe(SO4)2. After centrifugation, the supernatants were acidified to pH 2 with 6 mol/L HCl. The humic acids, which precipitated, were removed by centrifugation. The supernatant was further purified by solid phase extraction. The lignin-derived phenols were sorbed from the acidic solution on C18 material and later eluted with ethyl acetate. The solvent was removed by rotary evaporation, and the phenolic oxidation products were transferred to autosampler vials with methanol that was then removed under a flux of N2. Before analysis by GC/MS, the samples were dissolved in acetonitrile and derivatized with N,O-bis-(trimethylsilyl)trifluoroacetamid (BSTFA) for 1 h at room temperature. Thereafter, they were diluted with acetonitrile according to the expected phenol concentrations. One microliter of each sample was injected in splitless mode, and the phenols were separated in a HP 6890 gas chromatograph equipped with a HP5MS column (30 m x 250 micrometer x 0.25 micrometer). The temperature program of the gas chromatograph was 100°C isothermal for 4 min, ramp to 220°C at 4°C min^-1 with a 5-min isothermal period at 120°C, isothermal at 220°C for 3 min, ramp to 300°C at 30°C min^-1, and final isothermal period for 10 min. The transfer line to the mass spectrometer was kept at 325°C throughout the analysis. The HP 5973 mass spectrometer was operated in the EI mode at 70 eV. The ion source temperature was 230°C, and the quadrupole was kept at 150°C. Compounds were quantified by integration of the base ions and by comparison of the peak areas with those of synthetic standards. Before oxidation, ethylvanillin was added as an internal standard for the determination of recovery. To rule out possible transformations of the internal standard during the oxidation step, blanks containing only ethylvanillin and the reagents were also processed. GC-FID analysis of these blanks displayed a single peak with the retention time of ethylvanillin, and there was no evidence of any transformation of ethylvanillin during the oxidation step under the experimental conditions. The internal standard was added at the beginning of the analysis to ensure that the internal standard and the lignin oxidation products have the same history during the entire analysis. On average, 75% of the added ethylvanillin was recovered after the complete analytical procedure; the range of recoveries was from 50% to 105%. Concentrations and delta13C of total organic carbon Approximately 20 mg of the homogenized sample were weighed into tared sample vessels for elemental composition (total carbon, total nitrogen, organic carbon) and for isotope analyses (delta13C of organic carbon). Total carbon was determined in a Carlo Erba/Fisons 1108 Elemental Analyzer after combustion. A second weighed sample split in tared silver foil vessels was treated with 2N HCl to remove inorganic carbon. On this sub-sample, the concentrations of TOC and isotope ratio delta13C of organic carbon (given in permil versus V-PDB) were determined simultaneously in a Carlo Erba/Fisons 1108 Elemental Analyzer connected to an isotope-ratio mass spectrometer (Finnigan Delta S). The reference gas was pure CO2 from a cylinder calibrated against carbonate (NBS- 18, 19, 20). The standard deviation for replicate analyses of delta13C was less than 0.2 permil. The original data were corrected for the addition of anthropogenic CO2 (Suess effect) by substracting – 1.48 permil from the measured delta13C values of total organic carbon.

Description: Dumped munitions contain various harmful substances which can affect marine biota like fish. One of them is mercury (Hg), included in the common explosive primer. Another is 4-aminodinitrotoluene (4-ADNT), an explosive-metabolite. 251 individual dab (Limanda limanda L.) caught at the dump site Kolberger Heide a and nearby reference sites in 2017 and 2018 were analysed. The table contain individual data on Hg, 4-aminodinitrotoluene, age, length, weight, sex and condition factor.