ALBERT

Description: The Indian Summer Monsoon (ISM) is a major global climatic phenomenon. Long-term precipitation proxy records of the ISM, however, are often fragmented and discontinuous, impeding an estimation of the magnitude of precipitation variability from the Last Glacial to the present. To improve our understanding of past ISM variability, we provide a continuous reconstructed record of precipitation and continental vegetation changes from the lower Ganges-Brahmaputra-Meghna catchment and the Indo-Burman ranges over the last 18,000 years (18 ka). The records derive from a marine sediment core from the northern Bay of Bengal (NBoB), and are complemented by numerical model results of spatial moisture transport and precipitation distribution over the Bengal region. The isotopic composition of terrestrial plant waxes (dD and d13C of n-alkanes) are compared to results from an isotope-enabled general atmospheric circulation model (IsoCAM) for selected time slices (pre-industrial, mid-Holocene and Heinrich Stadial 1). Comparison of proxy and model results indicate that past changes in the dD of precipitation and plant waxes were mainly driven by the amount effect, and strongly influenced by ISM rainfall. Maximum precipitation is detected for the Early Holocene Climatic Optimum (EHCO; 10.5-6 ka BP), whereas minimum precipitation occurred during the Heinrich Stadial 1 (HS1; 16.9-15.4 ka BP). The IsoCAM model results support the hypothesis of a constant moisture source (i.e. the NBoB) throughout the study period. Relative to the pre-industrial period the model reconstructions show 20% more rain during the mid-Holocene (6 ka BP) and 20% less rain during the Heinrich Stadial 1 (HS1), respectively. A shift from C4-plant dominated ecosystems during the glacial to subsequent C3/C4-mixed ones during the interglacial took place. Vegetation changes were predominantly driven by precipitation variability, as evidenced by the significant correlation between the dD and d13C alkane records. When compared to other records across the ISM domain, precipitation and vegetation changes inferred from our records and the numerical model results provide evidence for a coherent regional variability of the ISM from the Last Glacial to the present.

Description: The core descriptions (chapter 7) summarize the most important results of the analysis of each sediment core following procedures applied during ODP/IODP expeditions. All cores were opened, described, and color-scanned. In the core descriptions the first column displays the lithological data that are based on visual analysis of the core and are supplemented by information from binocular and smear slide analyses. The sediment classification largely follows ODP/IODP convention. Lithological names consist of a principal name based on composition, degree of lithification, and/or texture as determined from visual description and microscopic observations. In the structure column the intensity of bioturbation together with individual or special features (turbidites, volcanic ash layers, plant debris, shell fragments, etc.) is shown. The hue and chroma attributes of color were determined by comparison with the Munsell soil color charts and are given in the color column in the Munsell notation. A GretagMacbethTM Spectrolino spectrophotometer was used to measure percent reflectance values of sediment color at 36 wavelength channels over the visible light range (380-730 nm) on all of the cores. The digital reflectance data of the spectrophotometer readings were routinely obtained from the surface (measured in 1 cm steps) of the split cores (archive half). The Spectrolino is equipped with a measuring aperture with folding mechanism allowing an exact positioning on the split core and is connected to a portable computer. The data are directly displayed within the software package Excel and can be controlled simultaneously. From all the color measurements, for each core the red/blue ratio (700 nm/450 nm) and the lightness are shown together with the visual core description. The reflectance of individual wavelengths is often significantly affected by the presence of minor amounts of oxyhydroxides or sulphides. To eliminate these effects, we used the red/blue ratio and lightness.

Description: The Baltic coast of Mecklenburg-Vorpommern is located in the transition Zone between the region of Fennoscandian Uplift and the Central European Depression. In relation to the eustatic sea-level rise, the northeast coast shows a slower inundation, while for the southwestern area a faster transgression is indicated, which can be attributed to crustal movements. To determine the spatial and temporal differences since the onset of the Littorina Transgression, three relative sea-level curves have been established along a transect parallel to the gradient of upliftlsubsidence. The Wismar Bay area is one endpoint of the transect demonstrating today 10 Abb., 2 Tab. a relative sea-level rise of 1.4 mm/a. To determine the relative sea-level curve for the Wismar Bay, two sites were investigated on Rustwerder Spit (Poel) and Redentin. They provided reliable depth-age data, while the stratigraphy was additionally supported by lithological/geochemical, pollen, diatom and macrofossil data. Additional evidence was provided by archaeological submarine surveys and excavations. Comparing the new relative sea-level curve with a curve from the Vorpommern coast, it can be shown that for the period from 4000 cal BC until present, the differences between the two curves are caused by a constant neotectonic movement, while for the older periods an increasing isostatic component must be taken into account.

Description: Euphausiids constitute major biomass component in shelf ecosystems and play a fundamental role in the rapid vertical transport of carbon from the ocean surface to the deeper layers during their daily vertical migration (DVM). DVM depth and migration patterns depend on oceanographic conditions with respect to temperature, light and oxygen availability at depth, factors that are highly dependent on season in most marine regions. Changes in the abiotic conditions also shape Euphausiid metabolism including aerobic and anaerobic energy production. Here we introduce a global krill respiration model which includes the effect of latitude (LAT), the day of the year of interest (DoY), and the number of daylight hours on the day of interest (DLh), in addition to the basal variables that determine ectothermal oxygen consumption (temperature, body mass and depth) in the ANN model (Artificial Neural Networks). The newly implemented parameters link space and time in terms of season and photoperiod to krill respiration. The ANN model showed a better fit (r**2=0.780) when DLh and LAT were included, indicating a decrease in respiration with increasing LAT and decreasing DLh. We therefore propose DLh as a potential variable to consider when building physiological models for both hemispheres. We also tested for seasonality the standard respiration rate of the most common species that were investigated until now in a large range of DLh and DoY with Multiple Linear Regression (MLR) or General Additive model (GAM). GAM successfully integrated DLh (r**2= 0.563) and DoY (r**2= 0.572) effects on respiration rates of the Antarctic krill, Euphausia superba, yielding the minimum metabolic activity in mid-June and the maximum at the end of December. Neither the MLR nor the GAM approach worked for the North Pacific krill Euphausia pacifica, and MLR for the North Atlantic krill Meganyctiphanes norvegica remained inconclusive because of insufficient seasonal data coverage. We strongly encourage comparative respiration measurements of worldwide Euphausiid key species at different seasons to improve accuracy in ecosystem modelling.