Down-core sedimentary Sr-Nd isotope records from two Cape Basin sediment cores in the South Atlantic: GeoB3603-2 (Meteor cruise M34/1) and MD02-2594 (Marion Dufresne cruise MD128)

We report down-core sedimentary Nd isotope (epsilon Nd) records from two South Atlantic sediment cores, MD02-2594 and GeoB3603-2, located on the western South African continental margin. The core sites are positioned downstream of the present-day flow path of North Atlantic Deep Water (NADW) and close to the Southern Ocean, which makes them suitable for reconstructing past variability in NADW circulation over the last glacial cycle. The Fe-Mn leachates epsilon Nd records show a coherent decreasing trend from glacial radiogenic values towards less radiogenic values during the Holocene. This trend is confirmed by epsilon Nd in fish debris and mixed planktonic foraminifera, albeit with an offset during the Holocene to lower values relative to the leachates, matching the present-day composition of NADW in the Cape Basin. We interpret the epsilon Nd changes as reflecting the glacial shoaling of Southern Ocean waters to shallower depths combined with the admixing of southward flowing Northern Component Water (NCW). A compilation of Atlantic epsilon Nd records reveals increasing radiogenic isotope signatures towards the south and with increasing depth. This signal is most prominent during the Last Glacial Maximum (LGM) and of similar amplitude across the Atlantic basin, suggesting continuous deep water production in the North Atlantic and export to the South Atlantic and the Southern Ocean. The amplitude of the epsilon Nd change from the LGM to Holocene is largest in the southernmost cores, implying a greater sensitivity to the deglacial strengthening of NADW at these sites. This signal impacted most prominently the South Atlantic deep and bottom water layers that were particularly deprived of NCW during the LGM. The epsilon Nd variations correlate with changes in 231Pa/230Th ratios and benthic d13C across the deglacial transition. Together with the contrasting 231Pa/230Th: epsilon Nd pattern of the North and South Atlantic, this indicates a progressive reorganization of the AMOC to full strength during the Holocene.

Alkenones and TEX86 temperature proxies for core-top sediments from the southern Adriatic Sea

The Mediterranean Sea is at the transition between temperate and tropical air masses and as such of importance for studying climate change. The Gulf of Taranto and adjacent SW Adriatic Sea are at the heart of this region. Their sediments are excellently suited for generating high quality environmental records for the last millennia with a sub-decadal resolution. The quality of these records is dependent on a careful calibration of the transfer functions used to translate the sedimentary lipid signals to the local environment. Here, we examine and calibrate the UK'37 and TEX86 lipid-based temperature proxies in 48 surface sediments and relate these to ambient sea surface temperatures and other environmental data. The UK'37-based temperatures in surface sediments reflect winter/spring sea surface temperatures in agreement with other studies demonstrating maximum haptophyte production during the colder season. The TEX86-based temperatures for the nearshore sites also reflect winter sea surface temperatures. However, at the most offshore sites, they correspond to summer sea surface temperatures. Additional lipid and environmental data including the distribution of the BIT index and remote-sensed chlorophyll-a suggest a shoreward increase of the impact of seasonal and spatial variability in nutrients and control of planktonic archaeal abundance by primary productivity, particle loading in surface waters and/or overprint by a cold-biased terrestrial TEX86 signal. As such the offshore TEX86 values seem to reflect a true summer signal to the effect that offshore UK'37 and TEX86 reconstruct winter and summer temperature, respectively, and hence provide information on the annual temperature amplitude.

(Table 1) Elemental composition of benthic foraminifera from South Atlantic core top samples

The ocean plays a major role in the global carbon cycle, and attempts to reconstruct past changes in the marine carbonate system are increasing. The speciation of dissolved uranium is sensitive to variations in carbonate system parameters, and previous studies have shown that this is recorded in the uranium-to-calcium ratio (U/Ca) of the calcite shells of planktonic foraminifera. Here we test whether U/Ca ratios of deep-sea benthic foraminifera are equally suited as an indicator of the carbonate system. We compare U/Ca in two common benthic foraminifer species (Planulina wuellerstorfi and Cibicidoides mundulus) from South Atlantic core top samples with the calcite saturation state (Delta [CO3**2-] = [CO3**2-]in situ - [CO3**2-]sat) of the ambient seawater and find significant negative correlations for both species. Compared with planktonic foraminifera, the sensitivity of U/Ca in benthic foraminifera to changes in Delta [CO3**2-] is about 1 order of magnitude higher. Although Delta [CO3**2-] exerts the dominant control on the average foraminiferal U/Ca, the intertest and intratest variability indicates the presence of additional factors forcing U/Ca.

Nematode abundance in cold seep sediments of the Nordic Margins (Nyregga, Styregga, Haakon Mosby Mud Volcano)

Cold-seep environments and their associated symbiont-bearing mega faunal communities create islands of primary production for macro-and meiofauna in the otherwise monotonous and nutrient-poor deep-sea environment. To examine the spatial variation and distribution patterns of metazoan meiobenthos in different seepage-related habitats, samples were collected in two regions off Norway: several pockmarks associated with the Storegga Slide including the Nyegga pockmark area, and the active, methane-venting Haakon Mosby Mud Volcano west of the Barents Sea during the Vicking cruise aboard the RV ''PourquoiPas?'' in May-June 2006. Meiofaunal samples at control sites were sampled with a multiple corer, while the other sites were sampled with push cores operated by the ROV Victor6000.The meiofaunal samples were fixed in 4% buffered formaldehyde and washed over a 32 mm-mesh sieve. Metazoan meiofauna were extracted by density gradient centrifugation. All material was fixed with 4% buffered formalin and stained with Rose Bengal. The metazoan meiofauna was sorted out, enumerated and identified down to major taxa under the stereomicroscope. Afterwards, abundances of Nematodes were depth integrated over the top 5 cm to gain individual abundances per 10 cm**2.