ALBERT

Description: FOR DOWNLOAD THE COMPLETE FILE PLEASE USE THE "OTHER VERSION". A joined data set of CTD profiles (conductivity, temperature, density, salinity, voltage and pressure) with metereological variables (daily mean, maximum and minimum air temperature; daily range temperature ?max-min); atmospheric pressure; relative humidity; precipitation; visibility; mean and max wind speed of day; wind gut; direction and cloud cover ) in Potter Cove, Carlini Station, King George Island (Isla 25 de Mayo). Stations have been merged within a neighbourhood of 0-100 m and concerning their membership to a geochemical cluster analysis (https://doi.pangaea.de/10.1594/PANGAEA.856971). 85 stations are remaining from the original data set (doi parent). The depth has been classified into three categories: 0-5 m; 5-15 m and over 15 m. Comment: As soon as there are CTD sample without metereology abailable it exists empty rows. Device used: CTD/Rosette (CTD-RO).

Description: The sediment trap experiment started in 1986 and was expanded into the Bay of Bengal only one year later in 1987. The fieldwork ended at around 1998. In 2007 and 2008, we tried to reinitiate a sediment trap program in the Arabian Sea, although this could not be followed up due to piracy, which became an issue in the region at that time. The sediment trap sites in the northern and central Bay of Bengal were shifted slightly southward in some years, whereby the stations NBBT and CBBT were spilt into northern (NBBT-N, CBBT-N) and southern sites (NBBT-S, CBBT-S). Between 2001 and 2004 additional sediment trap experiments were carried out in the upwelling system off South Java.

Description: Scavenger guilds are composed of a variety of species, co-existing in the same habitat and sharing the same niche in the food web. Niche partitioning among them can manifest in different feeding strategies, e.g. during carcass feeding. In the bentho-pelagic realm of the Southern Ocean, scavenging amphipods (Lysianassoidea) are ubiquitous and occupy a central role in decomposition processes. Here we address the question whether scavenging lysianassoid amphipods employ different feeding strategies during carcass feeding, and whether synergistic feeding activities may influence carcass decomposition. To this end, we compared the relatively large species Waldeckia obesa with the small species Cheirimedon femoratus, Hippomedon kergueleni, and Orchomenella rotundifrons during fish carcass feeding (Notothenia spp.). The experimental approach combined ex situ feeding experiments, behavioural observations, and scanning electron microscopic analyses of mandibles. Furthermore, we aimed to detect ecological drivers for distribution patterns of scavenging amphipods in the Antarctic coastal ecosystems of Potter Cove. In Potter Cove, the climate-driven rapid retreat of the Fourcade Glacier is causing various environmental changes including the provision of new marine habitats to colonise. While in the newly ice-free areas fish are rare, macroalgae have already colonised hard substrates. Assuming that a temporal dietary switch may increase the colonisation success of the most abundant lysianassoids C. femoratus and H. kergueleni, we aimed to determine their consumption rates (g food x g amphipods -1 x day -1) and preferences of macroalgae and fish.

Description: ICP-OES and ICP-MS data of trace elements in sediment and pore waters of the DISCOL area, Peru Basin, SE Pacific

Description: At present the Arabian Sea has a permanent oxygen minimum zone (OMZ) at water depths between about 100 m and 1200 m. Active denitrification in this OMZ is recorded by enhanced d15N values in the sediments. Sediment cores show a d15N increase from early to late Holocene which is contrary to the trend in other regions of water column denitrification. We calculated composite sea surface temperature (SST) and d15N in time slices of 1000 years of the last 25 ka to better understand the reasons for the establishment of the Arabian Sea OMZ and its response to changes in the Asian monsoon system. Pleistocene stadial d15N values of 4-6 per mil suggest that denitrification was inactive or weak. During interstadials (IS) and the entire Holocene, d15N values of 〉7 per mil indicate enhanced denitrification and a stronger OMZ. This coincides with active monsoonal upwelling along the western margins of the basin as indicated by low SST. Stronger ventilation of the OMZ in the early to mid-Holocene period during the most intense southwest monsoon and vigorous upwelling is reflected in lower d15N compared to the late Holocene. The displacement of the core of the OMZ from the region of maximum productivity in the western Arabian Sea to its present position in the northeast was established during the last 4-5 ka. This was probably caused by (i) rising oxygen consumption due to enhanced northeast monsoon driven biological productivity, in combination with (ii) reduced ventilation due to a longer residence time of OMZ waters.

Description: The Indian Monsoon and the westerlies strongly influence the sedimentation in the northeastern Arabian Sea by impacting rainfall and erosion on land and on biogeochemical processes in the ocean. To disentangle the terrestrial and oceanic processes, we analysed mineralogical and bulk geochemical components of a Holocene sediment core offshore Pakistan. Endmember modelling of grain sizes and principal component analyses (PCA) of major and trace elements identify the origin of sediments and their dominant mode of transport. Sedimentation processes during the early Holocene (10.8–8.2 ka BP) were influenced by the post-glacial sea level rise and orbitally forced strengthening of the Indian summer monsoon (ISM) and westerlies. This led to a shift from rather terrestrial-dominated towards a marine-dominated sedimentation, whereas the fluvial source shifted from the Makran rivers to the Hab River near Karachi. During the mid-Holocene (8.2–4.2 ka BP) a combination of weakening ISM and southward displacement of the ITCZ enhanced the influence of the westerlies, together decreasing river discharges and enhancing aeolian input (probably from the Sistan Basin region). This trend continued during the last ca. 4 ka when the increasing aridification of the Hab River catchment further increased the aeolian inputs. Solar and lunar driven short-term variations as well as Bond events known from the North Atlantic Ocean superpose these trends. They lead to a pronounced increase of fluvial inputs between 8.6–8.4 ka BP and at ca. 3 ka BP as well as to dry events around 4.2 ka and 1.2–1 ka BP. Our study highlights the increasing influence of the westerlies on the sedimentation processes in the northeastern Arabian Sea towards the late Holocene.

Description: To understand the fate of the increasing amount of macroalgal detritus in Antarctic shallow subtidal sediments, a mesocosm experiment was conducted to track 13C and 15N labelled macroalgal detritus into the benthic bacterial, meio- and macrofaunal biomass and respiration of sediments from Potter Cove (King George Island). We compared the degradation pathways of two macroalgae species: one considered palatable for herbivores (the red algae Palmaria decipiens), and one considered non-palatable for herbivores (the brown algae Desmarestia anceps). 15 sediment cores were taken from station Faro at 20m water depth. 13C and 15N labelled macroalgae were added to 10 cores: 5 cores received Desmarestia anceps, 5 cores received Palmaria decipiens. 5 cores did not receive any macroalgae and acted as a control. At different points in time, the cores were closed airtight for a dark incubation of 12h, during which oxygen was measured to calculate Total Oxygen Uptake (TOU), next to 13C-DIC, total nutrients and 15N-labelled nutrients (NH4, NOx and N2). The next day, the cores were sacrificed to determine the assimilation of macroalgae detritus in bacteria, microphytobenthos, meiofauna, macrofauna. Also the remaining large (〉1mm) macroalgae fragments were recovered and the bulk POC and PN of the sediment was measured. The sampling points are 1d after addition, and 7, 14 and 21 and 26 days after addition of macroalgae detritus.

Description: This is a an inventory of 86, mainly published, temperature records of northeastern North America and the northwestern Atlantic, covering the Holocene. Most records were published before and some of these have been updated applying new modern training sets for reconstruction and/or updated chronologies. Reconstructions were obtained from marine and terrestrial sites and a range of proxies, including pollen, dinocysts, chironomids, alkenones, varve characteristics and isotopes. Reconstruction and age uncertainties are provided when available.