ALBERT

Description: Assemblages of organic-walled dinoflagellate cysts (dinocysts) from 116 marine surface samples have been analysed to assess the relationship between the spatial distribution of dinocysts and modern local environmental conditions [e.g. sea surface temperature (SST), sea surface salinity (SSS), productivity] in the eastern Indian Ocean. Results from the percentage analysis and statistical methods such as multivariate ordination analysis and end-member modelling, indicate the existence of three distinct environmental and oceanographic regions in the study area. Region 1 is located in western and eastern Indonesia and controlled by high SSTs and a low nutrient content of the surface waters. The Indonesian Throughflow (ITF) region (Region 2) is dominated by heterotrophic dinocyst species reflecting the region's high productivity. Region 3 is encompassing the area offshore north-west and west Australia which is characterised by the water masses of the Leeuwin Current, a saline and nutrient depleted southward current featuring energetic eddies.

Description: Long-term changes in vegetation and climate of southern Brazil, as well as ocean dynamics of the adjacent South Atlantic, were studied by analyses of pollen, spores and organic-walled dinoflagellate cysts (dinocysts) in marine sediment core GeoB2107-3 collected offshore southern Brazil covering the last 73.5 cal kyr BP. The pollen record indicates that grasslands were much more frequent in the landscapes of southern Brazil during the last glacial period if compared to the late Holocene, reflecting relatively colder and/or less humid climatic conditions. Patches of forest occurred in the lowlands and probably also on the exposed continental shelf that was mainly covered by salt marshes. Interestingly, drought-susceptible Araucaria trees were frequent in the highlands (with a similar abundance as during the late Holocene) until 65 cal kyr BP, but were rare during the following glacial period. Atlantic rainforest was present in the northern lowlands of southern Brazil during the recorded last glacial period, but was strongly reduced from 38.5 until 13.0 cal kyr BP. The reduction was probably controlled by colder and/or less humid climatic conditions. Atlantic rainforest expanded to the south since the Lateglacial period, while Araucaria forests advanced in the highlands only during the late Holocene. Dinocysts data indicate that the Brazil Current (BC) with its warm, salty and nutrient-poor waters influenced the study area throughout the investigated period. However, variations in the proportion of dinocyst taxa indicating an eutrophic environment reflect the input of nutrients transported mainly by the Brazilian Coastal Current (BCC) and partly discharged by the Rio Itajaí (the major river closest to the core site). This was strongly related to changes in sea level. A stronger influence of the BCC with nutrient rich waters occurred during Marine Isotope Stage (MIS) 4 and in particular during the late MIS 3 and MIS 2 under low sea level. Evidence of Nothofagus pollen grains from the southern Andes during late MIS 3 and MIS 2 suggests an efficient transport by the southern westerlies and Argentinean rivers, then by the Malvinas Current and finally by the BCC to the study site. Major changes in the pollen/spore and dinocyst assemblages occur with similar pacing, indicating strongly interlinked continental and marine environmental changes. Proxy comparisons suggest that the changes were driven by similar overarching factors, of which the most important was orbital obliquity.

Description: The pollen, spore and organic walled dinoflagelletas cyst associations of two marine sediment cores from the Java Sea off the mouths of Jelai River (South Kalimantan) and Solo River (East Java) reflect environment and vegetation changes during the last ca 3500 years in the region. A decline in primary forest taxa (e.g. Agathis, Allophylus, Dacrycarpus, Dacrydium, Dipterocarpaceae, Phyllocladus, and Podocarpus) suggest that the major change in vegetation is caused by the forest canopy opening that can be related to human activity. The successively increase of pollen of pioneer canopy and herb taxa (e.g. Acalypha, Ficus, Macaranga/Mallotus, Trema, Pandanus) indicate the development of a secondary vegetation. In Java these changes started much earlier (ca at 2950 cal yr BP) then in Kalimantan (ca at 910 cal yr BP) and seem to be more severe. Changes in the marine realm, reflected by the dinoflagellate cyst association correspond to changes in vegetation on land. They reflect a gradual change from relatively well ventilated to more hypoxic bottom/pore water conditions in a more eutrophic environment. Near the coast of Java, the shift of the water trophic status took place between ca 820 and 500 cal yrs BP, while near the coast of Kalimantan it occurred as late as at the beginning of the 20th century. We observe an increasing amount of the cyst of Polykrikos schwarzii, cyst of P. kofoidii, Lingulodinium machaerophorum, Nematosphaeropsis labyrinthus and Selenopemphix nephroides at times of secondary vegetation development on land, suggesting that these species react strongly on human induced changes in the marine environment, probably related to increased pollution and eutrophication.

Description: The timing of the Monte Peron Landslide is revised to 2890 cal. BP based on a radiocarbon-dated sediment stratigraphy of Lago di Vedana. This age fosters the importance of hydroclimatic triggers in the light of accelerating global warming with a predicted increase of precipitation enhancing the regional predisposition to large landslides. Moreover, a layer enriched in allochthonous organic and minerogenic detritus dating to the same wet period is interpreted as response to a younger and yet unidentified mass wasting event in the catchment of Lago di Vedana. Rock debris of the Monte Peron Landslide impounded the Cordevole River valley and created a landslide-dammed lake. Around AD 1150, eutrophication of this lacustrine ecosystem started with intensified human occupation – a process that ended 150 years later, when the river was diverted back into its original bed. Most likely, this occurred due to artificial opening of the river dam. In consequence, Lago di Vedana was isolated from an open and minerogenic to an endorheic and carbonaceous lacustrine system. After a monastery was established nearby in AD 1457, a second eutrophication process was initiated due to intensified land use linked with deforestation. Only in the 18th and 19th century, deposition of organic matter decreased coinciding with climatic (Little Ice Age) and cultural changes. Conversational measures are the likely reasons for a trend towards less eutrophic conditions since AD 1950.

Description: The dataset represents pollen and sedimentary charcoal counting data as well as XRF and grain size data of the lacustrine sediment core recovered from Lake Maudit in Montagne d'Ambre (northern Madagascar, 1,250 m asl). From the center of the Lake Maudit, accessible from a peat bog, two parallel sediment cores (LM1A and LM1B) with lengths of 10.5 m and 10.75 m were recovered in 2017 using a Russian peat corer in June 2017 by Vincent Montade, Laurent Bremond and Sandratrinirainy Ranarilalatiana. For pollen and extraction, 0.5 cm3 subsamples at an interval varying between 8 and 48 cm on LM1B were treated with hydrochloric acid, hydrofluoric acid, acetolysis mixture and stored in glycerol. A minimum sum of 300 terrestrial pollen grains was counted for each subsample using a light microscope at 400x magnification. Pollen and fern-spore percentages were calculated on the terrestrial pollen sum. For charcoal-particle extraction, 1 cm3 of sediment was sampled every cm along the core LM1B and soaked in a 3% NaP2O4 solution plus bleach for several hours to deflocculate sediments and oxidize organic matter. Samples were sieved through a 160 μm mesh and charcoal particles were counted using a stereomicroscope at x40 magnification coupled to a digital camera. Semi-quantitative measurements of inorganic chemical elements were conducted using an ITRAX (CS-8) X-Ray fluorescence (XRF) core scanner with a molybdenum (Mo) tube at the Geomorphological–Sedimentological Laboratory of the Geomorphology and Polar Research (GEOPOLAR), University of Bremen. XRF scanning was conducted at 55 kV and 30 mA with 10 s of exposure time at 0.2 mm resolution from both sediment cores, LM1A and LM1B. These elements were normalized to the counts of incoherent radiation (“Mo inc”) derived from the XRF scanner, to account for lithological changes and sediment matrix effects. Using the XRF data, a Principal Component Analysis (PCA) was carried out, using the selected elements (Si, K, Ca, Ti, Mn, Fe, and Ni) as input variables. Prior to this multivariate statistic, the normalized elements were transformed using standard “z-transformation”. The PCA carried out with XRF data resulted in three main axes, with Axis 1 representing 61.5%, Axis 2 24.4%, and Axis 3 9.4% of the total data variance. For the grain size analysis ~1 cm3 subsamples at an interval of 5 cm were taken on LM1A and measured after destroying carbonates and organic matter according to standard protocols with HCl and H2O2. Measurements were carried out with a laser diffraction particle-size analyzer (LS 13320 Beckman Coulter) in seven cycles of 60 s each. The first reproducible signal was considered as reliable and final distribution data were calculated using the Fraunhofer optical model. Based on the lithological description (marker layers), the XRF-element patterns, and digital and radiographic images, LM1A and LM1B were parallelized and combined to a composite core (depth 1). In addition, several event-related deposits (deposited within only hours or maybe days) originating from the catchment have been identified. These events disturbed the normal sedimentation process and were removed to correct the master core depth (depth 2) before establishing the age-depth model. Between 0 and 208 cm the sediment core corresponds to peat sediment and below 208 cm to lacustrine sediment. Age-depth model have been only established on the lacustrine sediment section.

Description: The brGDGT abundances was microwave extracted from the sediment using (DCM):MeOH solvent twice. Then the polar and apolar part were separated and undergo High Performance Liquid Chromatography Mass Spectrometery (HPLC-APCI-MS, Agilent 1200) to quantify brGDGT concentration and fractional abundances.