d15N of trap WR2

Temporal changes in d15N values of sinking particles collected with sediment traps in the Benguela upwelling regime off southwest Africa mirrored variations in the input of inorganic nitrogen to the surface water. Reductions in d15N (to as low as 2.5 per mil) corresponded to low sea surface temperatures during austral spring and late austral autumn/early winter, indicating increased nitrate availability due to the presence of recently upwelled water. High particulate fluxes accompanied the low d15N values and sea surface temperatures, reflecting increased productivity, fueled by the upwelled nutrients. High d15N values (up to 13.1 per mil) coincided with high sea surface temperatures and low particle fluxes. In this area, the seaward extension of upwelling filaments, which usually occurs twice yearly, brings nutrient-rich water to the euphotic zone and leads to elevated productivity and relatively lower d15N values of the particulate nitrogen. Satellite images of ocean chlorophyll show that productivity variations coincide with d15N changes. The observed isotopic pattern does not appear to have been caused by variations in the species composition of the phytoplankton assemblage. Calculations based on d15N of the sinking particulate nitrogen show that the surface nitrate pool was more depleted during late austral summer/early fall and mid-winter and that supply exceeded demand during the intense spring bloom and in late austral fall. The main uncertainty associated with these estimates is the effect of diagenesis on d15N and possible variability in preservation of the isotope signal between periods of high and low particle flux.

47 ground-penetrating radar lines of Area 4 - Gravel spit system from Potter Cove, King George Island, Antarctic Peninsula

During two field campaigns (Austral springs 2011 and 2012) the sedimentary architecture of a polar gravel-spit system at the northern coast of Potter Peninsula (Area 4) was revealed using ground-penetrating radar (GPR, Geophysical Survey Systems, Inc. SIR-3000). 47 profiles were collected using a mono-static 200 MHz antenna operated in common offset mode. Trace increment was set to 0.05 m. A differential global-positioning system (dGPS, Leica GS09) was used to obtain topographical information along the GPR lines. GPR data are provided in RADAN-Format, dGPS coordinates are provided in ascii format; projection is UTM (WGS 84, zone 21S).

Paleoclimate investiations on sediment core MD01-2378

We present a high-resolution (not, vert, similar 60-110 yr) multi-proxy record spanning Marine Isotope Stage 3 from IMAGES Core MD01-2378 (13°04.95'S and 121°47.27'E, 1783 m water depth), located in the Timor Sea, off NW Australia. Today, this area is influenced by the Intertropical Convergence Zone, which drives monsoonal winds during austral summer and by the main outflow of the Indonesian Throughflow, which represents a key component of the global thermohaline circulation system. Thus, this core is ideally situated to monitor the linkages between tropical and high latitude climate variability. Benthic d18O data (Planulina wuellerstorfi) clearly reflect Antarctic warm events (A1-A4) as recorded by the EPICA Byrd and Dronning Maud Land ice cores. This southern high latitude signal is transferred by deep and intermediate water masses flowing northward from the Southern Ocean into the Indian Ocean. Planktonic d18O shows closer affinity to northern high latitudes planktonic and ice core records, although only the longer-lasting Dansgaard-Oeschger warm events, 8, 12, 14, and 16-17 are clearly expressed in our record. This northern high latitude signal in the surface water is probably transmitted through atmospheric teleconnections and coupling of the Asian-Australian monsoon systems. Benthic foraminiferal census counts suggest a coupling of Antarctic cooling with carbon flux patterns in the Timor Sea. We relate increasing abundances of carbon-flux sensitive species at 38-45 ka to the northeastward migration of the West Australian Current frontal area. This water mass reorganization is also supported by concurrent decreases in Mg/Ca and planktonic d18O values (Globigerinoides ruber white).

Distribution of organic-walled dinoflagellate cysts in surface sediments of the Benguela upwelling system

To obtain insight in the relationship between the spatial distribution of organic-walled dinoflagellate cysts (dinocysts) and local environmental conditions, fifty-eight surface sediment samples from the coastal shelf off SW Africa were investigated on their dinocyst content with special focus on the two main river systems and the active upwelling that characterise this region. To avoid possible overprint by species-selective preservation, samples have been selected mainly from shelf sites where high sedimentation rates and/or low bottom water oxygen concentrations prevail. Multivariate ordination analyses have been carried out to investigate the relationship between the distribution patterns of individual species to environmental parameters of the upper water column and sediment transport processes. The main oceanographical variables at the surface (temperature, salinity, nutrients chlorophyll-a) in the region show onshore-offshore gradients. This pattern is reflected in the dinocyst associations with high relative abundances of heterotrophic dinocyst species in neritic regions characterised by high chlorophyll-aand low salinity conditions in surface waters. Phototrophic dinocyst species, notably Operculodinium centrocarpum, dominate in the more oceanic area. Differences in the distribution of phototrophic dinocyst species can be related to sea surface salinity and sea surface temperature gradients and to a lesser extent to chlorophyll-a concentrations. Apart from longitudinal gradients the dinocyst distribution clearly reflects regional environmental features. Six groups of species can be distinguished, characteristic for (1) coastal regions (cysts of Polykrikos kofoidii and Selenopemphix quanta), (2) the vicinity of active upwelling (Brigantedinium spp., Echinidinium aculeatum, Echinidinium spp. and Echinidinium transparantum), (3) river mouths (Lejeunecysta oliva, cysts of Protoperidinium americanum, Selenopemphix nephroides and Votadinium calvum), (4) slope and open ocean sediments (Dalella chathamense, Impagidinium patulum and Operculodinium centrocarpum, (5) the southern Benguela region (south of 24°S) (Spiniferites ramosus) and (6) the northern Benguela region (north of 24°S) (Nematosphaeropsis labyrinthus and Pyxidinopsis reticulata). No indication of overprint of the palaeo-ecological signal by lateral transport of allochthonous species could be observed.

Benthic foraminifers in Mesozoic and Cenozoic sediments of the southwestern Atlantic

Benthic foraminiferal assemblages in Mesozoic and Cenozoic sediments were studied at Sites 511, 512, 513, and 514 drilled during Leg 71 in the southwestern Atlantic on the Maurice Ewing Bank and in the Argentine Basin. Benthic foraminifers in almost all stratigraphic subdivisions of Sites 511 and 512 reflect the gradual subsidence of the Falkland Plateau from shelf depths in the Barremian-Albian, when a semiclosed basin with restricted circulation of water masses and anaerobic conditions existed, to lower bathyal depths in the Late Cretaceous and Cenozoic, with an abrupt acceleration at the boundary of Lower and Upper Cretaceous. The composition, distribution, and preservation of Late Cretaceous assemblages of benthic foraminifers suggest considerable fluctuations of the foraminiferal lysocline and the CCD. This is evidenced by dissolution facies and foraminiferal assemblages in which agglutinated and resistant calcareous forms predominated during high stands of the CCD and by calcareous facies in which rich assemblages of calcareous species predominated during low stands. The highest position of the CCD on the Plateau (less than 1500-2000 m) was in the late Cenomanian, Turonian, and Coniacian. In the Santonian and Campanian the CCD was at depths below 1500-2000 meters. At the end of the Campanian the CCD shifted again to depths comparable with those of Cenomanian and Turonian time. In the latest Campanian and the Maestrichtian the CCD was low and nanno-foraminiferal oozes with a rich assemblage of benthic foraminifers accumulated. Foraminiferal assemblages at Sites 513 and 514 in the Argentine Basin also testify to oceanic subsidence from lower bathyal depths in the Oligocene to abyssal ones at present. This process was complicated by the influence of geographical migrations of the Polar Front caused by extensions of the ice sheet in the Antarctic after the opening of the Drake Passage during the Oligocene. In Mesozoic and Cenozoic deposits of the Falkland Plateau and the Argentine Basin seven assemblages of benthic foraminifers were distinguished by age: early-middle Albian, middle-late Albian, Late Cretaceous (including four groups), middle Eocene, late Eocene-early Miocene, middle-late Miocene, and Pliocene-Quaternary. The Albian assemblages contain many species common to the foraminiferal fauna of the Austral Biogeographical Province. The Late Cretaceous assemblage contains, along with Austral species, species common to foraminifers of North America, Western Europe, the Russian platform, and the south of the U.S.S.R. Deep-sea cosmopolitan species prevail in Cenozoic assemblages.

Paleotemperature reconstructions on sediment core GIK161603-3

Different proxies for sea surface temperature (SST) often exhibit divergent trends for deglacial warming in tropical regions, hampering our understanding of the phase relationship between tropical SSTs and continental ice volume at glacial terminations. To reconcile divergent SST trends, we report reconstructions of two commonly used paleothermometers (the foraminifera G. ruber Mg/Ca and the alkenone unsaturation index) from a marine sediment core collected in the southwestern tropical Indian Ocean encompassing the last 37,000 years. Our results show that SSTs derived from the alkenone unsaturation index (UK'37) are consistently warmer than those derived from Mg/Ca by ~2-3°C except for the Heinrich Event 1. In addition, the initial timing for the deglacial warming of alkenone SST started at ~15.6 ka, which lags behind that of Mg/Ca temperatures by 2.5 kyr. We argue that the discrepancy between the two SST proxies reflects seasonal differences between summer and winter rather than post-depositional processes or sedimentary biases. The UK'37 SST record clearly mimics the deglacial SST trend recorded in the North Atlantic region for the earlier part of the termination, indicating the early deglacial warming trend attributed to local summer temperatures was likely mediated by changes in the Atlantic Meridional Overturning Circulation at the onset of the deglaciation, In contrast, the glacial to interglacial SST pattern recorded by G. ruber Mg/Ca probably reflects cold season SSTs. This indicates that the cold season SSTs was likely mediated by climate changes in the southern hemisphere, as it closely tracks the Antarctic timing of deglaciation. Therefore our study reveals that the tropical southwestern Indian Ocean seasonal SST was closely linked to climate changes occurring in both hemispheres. The austral summer and winter recorded by each proxy is further supported with seasonal SST trends modeled by AOGCMs for our core site. Our interpretation that the alkenone and Mg/Ca SSTs are seasonally biased may also explain similar proxy mismatches observed in other tropical regions at the onset of the last termination.

(Table 1) Concentration of iron, DIP and silicic acid in water samples taken during Nathaniel B. Palmer cruises NBP06-01 and NBP06-08 (CORSACS I+II), Ross Sea

The Ross Sea polynya is among the most productive regions in the Southern Ocean and may constitute a significant oceanic CO2 sink. Based on results from several field studies, this region has been considered seasonally iron limited, whereby a "winter reserve" of dissolved iron (dFe) is progressively depleted during the growing season to low concentrations (~0.1 nM) that limit phytoplankton growth in the austral summer (December-February). Here we report new iron data for the Ross Sea polynya during austral summer 2005-2006 (27 December-22 January) and the following austral spring 2006 (16 November-3 December). The summer 2005-2006 data show generally low dFe concentrations in polynya surface waters (0.10 ± 0.05 nM in upper 40 m, n = 175), consistent with previous observations. Surprisingly, our spring 2006 data reveal similar low surface dFe concentrations in the polynya (0.06 ± 0.04 nM in upper 40 m, n = 69), in association with relatively high rates of primary production (~170-260 mmol C/m**2/d). These results indicate that the winter reserve dFe may be consumed relatively early in the growing season, such that polynya surface waters can become "iron limited" as early as November; i.e., the seasonal depletion of dFe is not necessarily gradual. Satellite observations reveal significant biomass accumulation in the polynya during summer 2006-2007, implying significant sources of "new" dFe to surface waters during this period. Possible sources of this new dFe include episodic vertical exchange, lateral advection, aerosol input, and reductive dissolution of particulate iron.

Respiration rate and ammonium excretion data for the squat lobster Pleuroncodes monodon measured during METEOR cruise M93

Sampling was conducted during RV Meteor cruise M93 in austral summer 2013 in an area from 11ºS to 14ºS and approximately 120 km offshore to within 10 km of the Peruvian coast. Specimens were collected using a Hydrobios Multinet Maxi (0.5 m2 mouth opening, 330 µm mesh size, 9 nets) and a WP-2 net (Hydrobios, 0.26 m2 mouth opening, 200 µm mesh size). P. monodon were identified according to http://researchdata.museum.vic.gov.au/squatlobster/delta/deltakey.html. Specimens were transferred into filtered, well-oxygenated seawater immediately after the catch and maintained for 4 to 16 hours prior to physiological experiments. Maintenance and physiological experiments were conducted at 13°C as the temperature observed at 100 to 200 m depth in the OMZ ranged from 13.7 to 12.7°C.

Depth profiles of iodide and iodate during POLARSTERN cruise ANT-XXIV/3 to the Atlantic sector of the Southern Ocean

The biogeochemistry of iodine in the waters of the Atlantic sector of the Southern Ocean was investigated during the Polarstern cruise ANTXXIV-3 ZERO&DRAKE. The speciation and distribution of iodine (iodate and iodide) in seawater was examined across gradients of iron concentrations and phytoplankton abundance, ranging from an open ocean region along the Zero Meridian to the Weddell Sea and Drake Passage. Iodine cycling in high latitudes differs from that in low latitudes due to differences in the plankton community composition and the physicochemical characteristics. Iodate concentrations ranged between 400 and 450 nmol/L from the surface to the bottom. Surface concentrations of iodide (17 to over 60 nmol/L) were about an order of magnitude higher than below the pycnocline. The peak values of iodide lay nearly always within the euphotic zone and showed a weak, positive correlation with nitrite concentrations in the upper 200 m. In all vertical profiles a pronounced sub-surface maximum in iodide appears between 50 and 200 m depth indicating an iodide drawdown at the near surface. Iodide distribution in the Weddell Sea showed elevated levels in Weddell Sea Bottom Water (WSBW) indicating slow oxidation kinetics and the potential for iodide as a tracer of WSBW formation.

Maestrichtian planktonic foraminifera of the Maud Rise

The southernmost record of Maestrichtian pelagic carbonate sedimentation was recovered from ODP Leg 113 Holes 689B and 690C, drilled on the Maud Rise in the eastern Weddell Sea sector of the Southern Ocean (65°S). Well preserved and abundant planktonic foraminifers occur throughout Maestrichtian cores from both holes, providing a nearly complete biogeographic and biostratigraphic history of this region. Diversity is low compared to tropical and subtropical assemblages, with a maximum within sample diversity of 16 planktonic foraminifer species and a diversity total for the Maestrichtian of 24 species. The assemblages are dominated throughout by Heterohelix, Globigerinelloides, and a new species of Archaeoglobigerina, whereas keeled taxa are completely absent from the lower Maestrichtian and rare in the middle through upper Maestrichtian sediments. Three planktonic foraminifer species are described as new and are recognized as being endemic to the Austral Province. These include Archaeoglobigerina australis n. sp., Hedbergella sliteri n. sp., and Archaeoglobigerina mateola n. sp. The former two species were previously illustrated in reports on Late Cretaceous foraminifers from the Falkland Plateau and the northern Antarctic Peninsula. Two keeled and five non-keeled planktonic foraminifers, previously not found in high latitude Maestrichtian sediments, first appeared at the Maud Rise during the late early and late Maestrichtian. Correlation with their stratigraphic ranges in low latitude sequences shows that their first appearance datums are considerably younger at the Maud Rise than in the lower latitudes. The most likely explanation for this observation is that there was a warming in the south polar region during the late early and late Maestrichtian and a concomitant poleward migration of stenothermal taxa. However, oxygen isotopic paleotemperature results from Sites 689 and 690 (Barrera and Huber, 1990, doi:10.2973/odp.proc.sr.113.137.1990) show a long-term cooling trend throughout the Maestrichtian, indicating that other factors may have played a more important role than temperature in the distribution of Maestrichtian planktonic foraminifers. A new biostratigraphic scheme is proposed for the Antarctic because of the absence of thermophilic planktonic foraminifers used to identify existing low to middle latitude zones. The Globigerinelloides impensus Partial Range Zone is defined for the late Campanian-Maestrichtian, the Globotruncanita havanensis Partial Range Zone is redefined for the early to late early Maestrichtian, and the Abathomphalus mayaroensis Total Range Zone is recognized. Good quality magnetic polarity data obtained from both Maud Rise sites (Hamilton, 1990, doi:10.2973/odp.proc.sr.113.179.1990) enables magnetobiostratigraphic correlation of twelve foraminifer datums with the geomagnetic polarity time scale of Haq et al. (1987). The geochronology thus obtained is crucial for accurate cross-latitudinal correlation and interpretation of the paleoceanographic history of the Antarctic region during the Maestrichtian time period.

Sedimentation in the vicinity of Leg 92 Drill Sites: Studies of site survey cores

Surveys of the areas surrounding the sites drilled on the Leg 92 19°S transect showed that sedimentation at all except the oldest site is dominated by calcium carbonate deposition. The sediments in the area of the oldest site, west of the Austral Fracture Zone, are being deposited beneath the calcium carbonate compensation depth and are dominated by terrigenous and metal-rich hydrogenous and hydrothermal sediments. The noncarbonate sediments in all of the areas east of the Austral Fracture Zone are dominated by hydrothermal sediment similar in composition to that presently being deposited at the East Pacific Rise. Although no biogenic microfossils were present in smear slides of the sediment, geochemical partitioning suggests that a remnant signal of siliceous biogenic deposition may be preserved, especially in gravity core (GC) 8, which was collected from a high heat flow zone near Site 600. The siliceous sediment may also result from the deposition of amorphous hydrothermal silica from the higher concentrations of pore water SiO2 characteristic of the upwelling waters. Sedimentation on the broad plateaus that characterize each area is quite uniform and suggests that sites on these plateaus will be broadly representative of pelagic sedimentation in the area.

Distribution of benthic foraminifera in lower Cretaceous sediments of the Cuvuer Abyssal Plain in the Indian Ocean

Analysis of 66 samples from DSDP Site 263 (Cores 263-4R-4 to 263-29R-4) reveals a unique faunal composition with a predominance of agglutinated taxa, many of them previously unrecorded from any other DSDP and ODP Indian Ocean sites. A total of 66 agglutinated and 31 calcareous taxa are documented and five new species are described: Hippocrepina gracilis n.sp., "Textuluriopsis" elegans n.sp., Aaptotoichus challengeri n.sp., "Gaudryinopsis" pseudobettenstaedti n.sp. and "Gaudryina" cuvierensis n.sp. Three assemblages are recognized based on changes in the composition of dominant taxa and occurrences of stratigraphically important species: (1) a high-diversity Valanginian to Barremian Bulbobaculites-Recurvoides Assemblage (Cores 263-29R to - 18R), comprised of numerous elongate agglutinated forms, rare nodosariids, and variable numbers of tubes and ammodiscids; (2) a moderately diverse Aptian to Albian Rhizammina-Ammodiscus-Glomospira Assemblage (Cores 263-18R to -7R) with highly fluctuating numbers of the nominate taxa and Haplophragmoides, Trochammina, Verneuilinoides spp., and Verneuilina howchini; (3) a very low diversity Albian or younger Assemblage (Cores 263-6R to -4R) containing sparse agglutinated foraminifera, rare nodosariids and rotaliids. We interpret the assemblages as shelf to lower slope and consider them to reflect a deepening palaeobathymetry as the Cuvier margin subsided after the initial breakup of East Gondwana during the Valanginian. Our interpretation is in sharp contrast with initial palaeodepth estimates of less than 100 m, as well as with original chronostratigraphic interpretations based on foraminifera and nannofossils which correlated the base of the recovered interval with the Aptian. The absence of many cosmoplitan forms, despite high diversity suggests strong faunal differentiation in the Austral realm or endemisn within the Cuvier Basin during the Early Cretaceous.

Environmental analyses of cyclic Middle Eocene sediments and palynomorph records of ODP Hole 189-1172A

The influence of orbital precession on early Paleogene climate and ocean circulation patterns in the southeast Pacific region is investigated by combining environmental analyses of cyclic Middle Eocene sediments and palynomorph records recovered from ODP Hole 1172A on the East Tasman Plateau with climate model simulations. Integration of results indicates that in the marine realm, direct effects of precessional forcing are not pronounced, although increased precipitation/runoff could have enhanced dinoflagellate cyst production. On the southeast Australian continent, the most pronounced effects of precessional forcing were fluctuations in summer precipitation and temperature on the Antarctic Margin. These fluctuations resulted in vegetational changes, most notably in the distribution of Nothofagus (subgenus Brassospora). The climate model results suggest significant fluctuations in sea ice in the Ross Sea, notably during Austral summers. This is consistent with the influx of Antarctic heterotrophic dinoflagellates in the early part of the studied record. The data demonstrate a strong precessionally driven climate variability and thus support the concept that precessional forcing could have played a role in early Antarctic glaciation via changes in runoff and/or precipitation.

Oceanographic Data of the 37th Japanese Antarctic Research Expedition from November 1995 to March 1996

The results of oceanographic observations on board the icebreaker "Shirase" and tidal observations at Syowa Station, Antarctica, are presented in this report. The oceanographic observations were carried out by the summer party of the 37th Japanese Antarctic Research Expedition (JARE-37) during the austral summer of 1995/1996. The tidal observations were carried out by the winter party of JARE-36 from February 1995 to January 1996.