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Vertical distribution in the sediment of the different animal groups found in station CON01-427 (Posolskoe Bank) in the dimictic zone of Lake Baikal, expressed as the number of individuals per m2.

The vertical distribution of organisms in the sediment indicates that animals can be present as deep as 15 cm although at very low abundance at such depths (Fig. 4, Fig. 5 and Fig. 6). Oligochaetes and nematods are the only groups able to deeply penetrate into the sediment at significant densities (Fig. 4) in contrast to all other groups, which stay closer to the sediment surface. Maximal densities however seem to shift to the sediment surface with increasing bathymetric depth, as suggested in Fig. 5 and Fig. 6, so that all animal groups are more concentrated near the surface in the deepest parts of Lake Baikal. In such case, the depth of sediment mixing due to bioturbation appears to decrease with increasing bathymetric depth (Fig. 2b).

Densities of benthic taxa with depth (CON 01-01 and CON 01-04 expeditions).

In all abyssal stations, densities are never over an average of c. 3100 individuals m−2 (Fig. 3, Table 1). In contrast, the shallow station (CON01-427, Posolskoe Bank) harbours the highest observed densities (oligochaetes reach densities as high as 13573 individuals m−2 on average). Gammarids are present in this latter station at 128 m deep, while they are absent from all deep stations. The presence of some groups is anecdotal, such as Hydrachnidia (one specimen in a core at 388 m and two specimens in a core at 625 m) and chironomid larvae (two larvae in a core at 625 m). Interestingly, the two deepest Vydrino cores (CON01-105-7, 600 m, and CON01-106-3, 700 m) are virtually free from animals, suggesting that these stations are perhaps the best choice for the study of stratigraphy and climate proxies.

Tiefenverteilung von häufigen benthischen Wirbellosen im Stechlinsee

Im August 2006 wurden Macrozoobenthosorganismen alle 5 m entlang eines ost-west Tiefengradienten von 5-50 m in der Nordbucht des Stechlinsees untersucht. Von 18 nachgewiesenen Organismengruppen waren 10 auf die oberen 15 m Wassertiefe beschränkt. Chironomiden, Oligochaeten und Megacyclops copepoden waren die häufigsten Organismen in allen Tiefen. Die Artendiversität und die Abundanz der Macrozoobenther nahmen mit zunehmender Tiefe ab.

Individual valve counts of diatoms in sediment core Haem13 from lake Hämelsee

This dataset provides counts of diatom valves for the Lateglacial sediment sequence retrieved from Lake Hämelsee (Germany) in 2013. Counts per taxon are presented against both depth (m) and age (cal yr. BP). The diatom data provides information on Lateglacial ecosystem dynamics and the dataset was used to interpret changes in aquatic diversity as well as in palaeolimnological conditions. A total of 78 samples were selected for diatom analysis using 2-5 cm sample intervals throughout the Lateglacial section of the core sequence, with a higher sampling resolution (1 cm intervals) around key transitions. Organic matter was removed from the samples (ca. 0.01 grams dried sediment) by oxidation using 5 ml of H2O2 (30%) and heating in a water bath at 70 °C for 24-28 hrs. Subsequently, a few drops of HCl (50%) were added to remove residual H2O2 and carbonates. Samples were washed by adding distilled water, shaking vigorously, centrifuging at 1200 rpm for 4 minutes, and removing the liquid using a pipette. This process was repeated 5 times, and a few drops of ammonia (NH3) were added to the solution prior to the final wash to prevent clumping of diatoms. Diatom slides were mounted using Naphrax and diatoms were identified using Krammer and Lange-Bertalot (1986–1991) and Camburn and Charles (2000). For several samples the target count sum of 300 diatom valves could not be reached due to low concentrations or poor diatom preservation. Prior to analysis and interpretation, and where possible, neighbouring samples with a low count sum were amalgamated until a count of at least 100 valves was reached; if this was not possible the samples were deleted from our dataset prior to subsequent analysis (note that these samples are still included in the dataset provided here). All analyses were performed in the laboratories of University College London, UK.

Dry mass concentrations of individual n-alkanes in sediment core Haem13 from lake Hämelsee

This dataset provides concentrations of n-alkanes for the Lateglacial sediment sequence retrieved from Lake Hämelsee (Germany) in 2013. Concentrations of n-alkanes (ug/g), the Carbon Preference Index (CPI) and the Average Chain Length C21-C33 (ACL) are all presented against both depth (m) and age (cal yr. BP). The n-alkane concentration data provides information on the Lateglacial dynamics of local plant productivity, whereas the ACL and CPI of the sediment samples were determined to estimate origin and preservation condition. A total of 167 samples from the Lateglacial section of the core were processed using a Dionex 350 accelerated solvent extraction (ASE) system. Solid phase extraction (SPE) was used to separate the extracts into an aliphatic, aromatic and alcohol/fatty acid fraction. Separation was achieved by loading the extracts on activated silica columns and eluting each fraction with hexane, hexane/DCM (1:1 v/v) and DCM/MeOH (9:1 v/v) successively. The aliphatic fraction, containing the n-alkanes, was analyzed by gas chromatography-mass spectrometry (GC/MS). The peak areas for each n-alkane homologue were compared to the peak areas from an internal standard (5α-androstane) and an external n-alkane standard mixture for absolute quantification. We refer to Rach et al. (2020) for further details on the exact analytical setup. All measurements were performed in the laboratories of GeoForschungsZentrum Potsdam.

Chironomidae whole or half head capsules counts in sediment core Haem13 from lake Hämelsee

This dataset provides counts of chironomid head capsules for the Lateglacial sediment sequence retrieved from Lake Hämelsee (Germany) in 2013. Counts per taxon are presented against both depth (m) and age (cal yr. BP), and the total amount of material used for analysis (in g) is provided as well. The chironomid data provides information on Lateglacial ecosystem dynamics and were used to interpret changes in aquatic diversity as well as in local climate conditions. A total of 123 samples from the Lateglacial section of the core were treated with warm KOH (10%) to de-flocculate the material and subsequently rinsed through a sieve with a 100-µm mesh. Chironomid head capsules (HCs) were hand-picked from the residue using a Bogorov sorting tray and mounted on permanent microscope slides using Euparal mounting medium. HCs were identified using Brooks et al. (2007) and the dataset presented here has been matched to the taxonomy of the merged Norwegian/Swiss chironomid-climate calibration dataset. Several samples had low chironomid concentrations and for these we amalgamated adjacent samples (within lithological boundaries) to reach a minimum count sum of 50 head capsules per sample. This process resulted in the final chironomid dataset that is presented here, containing 97 samples. All analyses were performed in the laboratories of the University of Amsterdam, the Netherlands.

GDGTs in sediment core Haem13 from lake Hämelsee

This dataset provides glycerol dialkyl glycerol tetraethers (GDGTs) concentrations for the Lateglacial sediment sequence retrieved from Lake Hämelsee (Germany) in 2013. GDGTs concentrations (ng/g) are presented against both depth (m) and age (cal yr. BP). The GDGTs dataset was used to calculate the GDGT-0/crenarchaeol ratio, which was interpreted to represent lake water oxygenation, which, given the local settings, was likely driven by changes in windiness. Additionally, the GDGT dataset was used to calculate the degree of methylation of 5-methyl brGDGTs (MBT'5me), which can be used to reconstruct past temperature change through translation MBT'5me into mean temperature of the months above freezing. As such, the GDGT data provides information on LGIT climate dynamics at lake Hämelsee. Of the 167 samples used for lipid extraction (see https://doi.pangaea.de/10.1594/PANGAEA.964524), the alcohol/fatty acid fraction of 94 samples was further processed to analyse glycerol dialkyl glycerol tetraethers (GDGTs), which are membrane lipids of certain archaea and bacteria (Schouten et al., 2013). In short, a known amount of internal standard was added to each fraction, which was then redissolved in hexane:isopropanol 99:1 and passed over a 0.45 µm PTFE filter prior to injection on a Agilent 1260 Infinity ultra-high performance liquid chromatograph coupled to an Agilent 6130 single quadrupole mass spectrometer following the settings and elution protocol of Hopmans et al. (2016). A minimum peak area of 3000 and a signal-to-noise ratio of >3 was maintained as detection limit. Quantification of the GDGTs is based on the assumption that the mass spectrometer equally responds to the GDGTs and the internal standard. All analyses were performed in the laboratories of Utrecht University, the Netherlands.

δDeuterium measurements of selected n-alkanes (corrected to the VSMOW scale) in sediment core Haem13 from lake Hämelsee

This dataset provides delta-Deuterium data for the Lateglacial sediment sequence retrieved from Lake Hämelsee (Germany) in 2013. Compound-specific hydrogen isotope ratios (expressed as δD) normalized to the Vienna Standard Mean Ocean Water (VSMOW) as well as measurement uncertainties (expressed as SD) are presented against both depth (m) and age (cal yr. BP). The data provides information on the Lateglacial development of local climate dynamics: the plant-wax derived δD signal is typically considered to reflect the hydrogen-isotopic composition of plant leaf water and, by extension, precipitation. We therefore interpret the trends in δD record here as an indicator of past hydrological change (cf Sachse et al., 2012). A total of 167 samples from the Lateglacial section of the core were processed using a Dionex 350 accelerated solvent extraction (ASE) system. Solid phase extraction (SPE) was used to separate the extracts into an aliphatic, aromatic and alcohol/fatty acid fraction. Prior to isotope ratio measurement, the aliphatic fraction was further fractionated on a Pasteur pipette column containing activated AgNO3 (10%) coated silica gel. Compound-specific hydrogen isotope ratios (expressed as δD) were subsequently measured on an isotope ratio mass spectrometer. All δD values are normalized to the Vienna Standard Mean Ocean Water (VSMOW) scale using a linear regression function between measured and certified δD values of a standard mix. We refer to Rach et al. (2020) for further details on the exact analytical setup. All measurements were performed in the laboratories of GeoForschungsZentrum Potsdam.

Vertical distribution in the sediment of the different animal groups found in station CON01-416 (Continent Ridge) in the abyssal zone of Lake Baikal, expressed as the number of individuals per m2.

The vertical distribution of organisms in the sediment indicates that animals can be present as deep as 15 cm although at very low abundance at such depths (Fig. 4, Fig. 5 and Fig. 6). Oligochaetes and nematods are the only groups able to deeply penetrate into the sediment at significant densities (Fig. 4) in contrast to all other groups, which stay closer to the sediment surface. Maximal densities however seem to shift to the sediment surface with increasing bathymetric depth, as suggested in Fig. 5 and Fig. 6, so that all animal groups are more concentrated near the surface in the deepest parts of Lake Baikal. In such case, the depth of sediment mixing due to bioturbation appears to decrease with increasing bathymetric depth (Fig. 2b).

Besiedlung von Totholz in Baechen des Mittelgebirges und des Tieflandes Nordrhein-Westfalens

In Abschnitten naturnaher Mittelgebirgs- und Tieflandbaeche in der Eifel und im Muensterland wird z.Zt. saemtliches im Gewaesserbett vorhandene Totholz kartiert. Um in den naechsten Jahren Abbau, Neuanfall und Verlagerung von Totholz bestimmen zu koennen, werden alle Totholzstuecke markiert. Auf diese Art soll Totholzeintrag und -stabilitaet in naturnahen Baechen untersucht werden. Mit Hilfe von Benthosaufsammlungen, Emergenzfaengen und Darminhaltsanalysen wird die Besiedlung aquatischen Totholzes mit xylophagen Arthropoden untersucht. Der Schwerpunkt der Arbeiten liegt auf Quellbaechen im Mittelgebirgsbereich und auf naturnahen Tieflandbaechen. Aufbauend auf den geschilderten Untersuchungen werden Arbeiten zur Oekologie ausgewaehlter totholzbewohnender Insektenarten (Trichoptera, Coleoptera, Diptera: Limoniidae und Chironomidae) durchgefuehrt. Schwerpunkte sind die Ernaehrungsgewohnheiten der Larven, das Ausbreitungsverhalten der Larven und der Imagines sowie die Eiablage.

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