Micropaleontological investigation of sediment core Kronsmoor

Benthic foraminiferal and calcareous nannofossil assemblages, as well as stable isotope data from the Campanian/Maastrichtian boundary interval (~71.4 to ~70.7 Ma) of the Kronsmoor section (North German Basin), were investigated in order to characterize changes in surface-water productivity and oxygen content at the seafloor and their link to climatic and paleoceanographic changes. A nutrient index based on calcareous nannofossils is derived for the high-latitude, epicontinental North German Basin, reflecting changes in surface-water productivity. Oxygen isotopes of well-preserved planktic foraminiferal specimens of Heterohelix globulosa reflect warmer surface-water temperatures in the lower part of the studied succession and a cooling of up to 2°C (0.5 per mil) in the upper part (after 71.1 Ma). For the lower and warmer part of the investigated succession, benthic foraminiferal assemblages and the calcareous nannofossils indicate well-oxygenated bottom waters and low-surface water productivity. In contrast, the upper part of the succession is characterized by cooler conditions, lower oxygen content at the seafloor and increasing surface-water productivity. It is proposed that the cooling phase starting at 71.1 Ma was accompanied by increasing surface-water mixing caused by westerly winds. As a consequence of mixing, nutrients were advected from sub-surface waters into the mixed layer, resulting in increased surface-water productivity and enhanced organic matter flux to the seafloor. We hypothesize that global sea-level fall during the earliest Maastrichtian (~71.3 Ma), indicated by decreasing carbon isotope values, may have led to a weaker water mass exchange through narrower gateways between the Boreal Realm and the open North Atlantic and Tethys oceans. Both the weaker water mass exchange and enhanced surface-water productivity may have led to slightly less ventilated bottom waters of the upper part of the studied section. Our micro-paleontological and stable isotopic approach indicates short-term (<100 kyr) changes in oxygen consumption at the seafloor and surface-water productivity across the homogeneous Boreal White Chalk succession of the North German Basin.

Grain-size, lithic grains, foraminifera-derived and dinocyst-derived data of sediment core MD99-2281

The last glacial period was punctuated by abrupt climatic events with extrema known as Heinrich and Dansgaard-Oeschger events. These millennial events have been the subject of many paleoreconstructions and model experiments in the past decades, but yet the hydrological processes involved remain elusive. In the present work, high-resolution analyses were conducted on the 12-42 ka BP section of core MD99-2281 retrieved southwest of the Faeroe Islands, and combined with analyses conducted in two previous studies (Zumaque et al., 2012; Caulle et al., 2013). Such a multiproxy approach, coupling micropaleontological, geochemical and sedimentological analyses, allows us to track surface, subsurface, and deep hydrological processes occurring during these rapid climatic changes. Records indicate that the coldest episodes of the studied period (Greenland stadials and Heinrich stadials) were characterized by a strong stratification of surface waters. This surface stratification seems to have played a key role in the dynamics of subsurface and deep-water masses. Indeed, periods of high surface stratification are marked by a coupling of subsurface and deep circulations which sharply weaken at the beginning of stadials, while surface conditions progressively deteriorate throughout these cold episodes; conversely, periods of decreasing surface stratification (Greenland interstadials) are characterized by a coupling of surface and deep hydrological processes, with progressively milder surface conditions and gradual intensification of the deep circulation, while the vigor of the subsurface northward Atlantic flow remains constantly high. Our results also reveal different and atypical hydrological signatures during Heinrich stadials (HSs): while HS1 and HS4 exhibit a "usual" scheme with reduced overturning circulation, a relatively active North Atlantic circulation seems to have prevailed during HS2, and HS3 seems to have experienced a re-intensification of this circulation during the middle of the event. Our findings thus bring valuable information to better understand hydrological processes occurring in a key area during the abrupt climatic shifts of the last glacial period.

Distribution of desmoscolecida (Nematoda) in surface sediments of the Iberian Deep-Sea, North Atlantic (Table 1)

1. Desmoscolecida from the continental slope and the deep-sea bottom (59-4354 m) off the Portuguese and Moroccan coasts are described. 18 species were identified: Desmoscolex bathyalis sp. nov., D. chaetalatus sp. nov., D. eftus sp. nov., D. galeatus sp. nov., D. lapilliferus sp. nov., D. longisetosus Timm, 1970, D. lorenzeni sp. nov., D. perspicuus sp. nov., D. pustulatus sp. nov., Quadricoma angulocephala sp. nov., Q. brevichaeta sp. nov., Q. iberica sp. nov., Q. loricatoides sp. nov., Tricoma atlantica sp. nov., T. bathycola sp. nov., T. beata sp. nov., T. incomposita sp. nov., T. meteora sp. nov., T. mauretania sp. nov. 2. The following new terms are proposed: "Desmos" (ring-shaped concretions consisting of secretion and concretion particles), "desmoscolecoid" and "tricomoid" arrangement of the somatic setae, "regelmaessige" (regular), "unregelmaessige" (irregular), "vollstaendige" (complete) and "unvollstaendige" (incomplete) arrangement of somatic seta (variations in the desmoscolecoid arrangement of the somatic setae). The length of the somatic setae is given in the setal pattern. 3. Desmoscolecida identical as to genus and species exhibit no morphological differences even if forthcoming from different bathymetrical zones (deep sea, sublitoral, litoral) or different environments (marin, freshwater, coastal subsoil water, terrestrial environment). 4. Lorenzen's (1969) contention that thearrangement of the somatic setae is more significant for the natural relationships between the different genera of Desmoscolecida than other characteristics is further confirmed. Species with tricomoid arrangement of somatic setae are regarded as primitive, species with desmoscolecoid arrangement of somatic setae are regarded as more advanced. 5. Three new genus are established: Desmogerlachia gen. nov., Desmolorenzenia gen. nov. and Desmofimmia gen. nov. - Protricoma Timm, 1970 is synonymized with Paratricoma Gerlach, 1964 and Protodesmoscolex Timm, 1970 is synonymized with Desmoscolex Claparede,1863. 6. Checklists of all species of the order Desmoscolecida and keys to species of the subfamilies Tricominae and Desmoscolecinae are provided. 7. The following nomenclatorial changes are suggested: Desmogerlachia papillifer (Gerlach, 1956) comb. nov., D .pratensis (Lorenz, 1969) comb. nov., Desmotimmia mirabilis (Timm, 1970) comb. nov., Paratricoma squamosa (Timm, 1970) comb. nov., Desmolorenzenia crassicauda (Timm, 1970) comb. nov., D. desmoscolecoides (Timm, 1970) comb. nov., D. eurycricus (Filipjev, 1922) comb. nov., D. frontalis (Gerlach, 1952) comb. nov., D. hupferi (Steiner, 1916) comb. nov., D. longicauda (Timm, 1970) comb. nov., D. parva (Timm, 1970) comb. nov., D. platycricus (Steiner, 1916) comb. nov., D. viffata (Lorenzen, 1969) comb. nov., Desmoscolex anfarcficos (Timm, 1970) comb. nov.

The near-bottom plankton and benthic invertebrate fauna of Josephine and Great Meteor Seamounts (Table 2)

15 samples obtained with Beyer's epibenthic closing net were studied quantitatively. The numbers of epi- and endobenthic animals were found to be correlated with the volume of sediment in the samples. Among the planktonic components, calanoid copepodes were strongly predominant. In the samples obtained on the Great Meteor Seamount, very much larger numbers of these animals were caught in the daytime than at night. Possible explanations for this difference are suggested.

Benthic foraminifera in surface sediments, South Atlantic

Sixty surface sediment samples from the eastern South Atlantic Ocean including the Walvis Ridge, the Angola and Cape basins, and the Southwest African continental margin were analysed for their benthic foraminiferal content to unravel faunal distribution patterns and ecological preferences. Live (stained with Rose Bengal) and dead faunas were counted separately and then each grouped by Q-mode principal component analysis into seven principal faunal end-members. Then, multiple regression technique was used to correlate Recent assemblages with available environmental variables and to finally differentiate between four principal groups of environmental agents acting upon the generation of benthic foraminiferal assemblages: (1) seasonality of food supply and organic carbon flux rates, together with oxygen content in the pore and bottom waters; (2) lateral advection of deep-water masses; (3) bottom water carbonate corrosiveness; and (4) energetic state at the benthic boundary layer and grain size composition of the substrate. Food supply and corresponding dissolved oxygen contents in the pore and bottom waters turned out to be the most important factors which control the distribution pattern of the Recent benthic foraminifera. At the continental margin, in the zone of coastal upwelling and its mixing area, benthic foraminiferal assemblages are dominated by stenobathic high-productivity faunas, characterized by elevated standing stocks, low diversities and a large number of endobenthic living species. At the continental shelf and upper continental slope the live assemblages are characterized by Rectuvigerina cylindrica, Uvigerina peregrina s.1., Uvigerina auberiana and Rhizammina spp. while the dead assemblages are characterized by Cassidulina laevigata, Bolivina dilatata, Bulimina costata and B. mexicana. At the lower continental slope strong influence of high organic matter fluxes on the species composition is restricted to the area off the Cunene river mouth, where the live assemblage is dominated by Uvigerina peregrina s.1., the corresponding dead assemblage by Melonis barleeanum and M. zaandamae. In the adjacent areas of the lower continental slope the biocoenosis is characterized by Reophax bilocularis, and Epistominella exigua which becomes dominant in the corresponding dead assemblage. At the Walvis Ridge and in the abyssal Angola and Cape basins, where organic matter fluxes are low and highly seasonal, benthic foraminiferal assemblages reflect both the oligotrophic situation and the deep and bottom water mass configuration. The top and flanks of the Walvis Ridge are inhabited by the Rhizammina, Psammosphaera and R. bilocularis live assemblages, the corresponding dead assemblages are dominated by G. subglobosa on the ridge top and E. exigua on the flanks. Within the highly diverse E. exigua dead assemblage several associated epibenthic species coincide with the core of NADW between about 1600 and 3700 m water depth. These species include Osangularia culter, Cibicidoides kullenbergi, Melonis pompilioides, Bolivinita pseudothalmanni and Bulimina alazanensis. The assemblages of the abyssal Cape and Angola basins are characterized by Nuttallides umbonifer and a high proportion of agglutinated species. These species are adapted to very low organic matter fluxes and a carbonate corrosive environment.

Benthos activity, abundance and biomass in surface sediments off Morocco, Northwest Africa

Macro- and meiobenthic abundance and biomass as well as metabolic activity (respiration, ETS activity) have been studied along a transect ranging from 130 to 3000 m water depth off northern Morocco (35° N) during "Meteor" cruise No. 53 (1980). The distribution of chloroplastic pigment concentration (chlorophyll a, pheophytins) in the sediment has been investigated as a measure of sedimented primary organic matter. High chloroplastic pigment concentrations were found on the shelf and around the shelf break, but values declined rapidly between 200 and 600 m depth. Below 1200 m pigment concentrations remained at a relatively uniform low level. Macrobenthic abundance and biomass (wet weight) decreased with increasing water depth and with distance from the shore. Significant changes occurred between the shelf and upper slope and below 2000 m depth. Meiobenthic abundance and biomass (ash free dry weight) followed the same general pattern, but changes were found below 400 and 800 m depth. In the depth range of 1200 to 3000 m values differ only slightly. Meiofauna abundance and biomass show a good correlation with the sedimentary chloroplastic pigment concentrations. Respiratory activity of sediment cores, measured by a shipboard technique at ambient temperatures, decreased with water depth and shows a good correlation with the pigment concentrations. ETS activity was highest on the shelf and decreased with water depth, with significant changes between 200 and 400 m, and below 1200 m depth, respectively. Activity was generally highest in the top 5 cm of the sediment and was measurable, at all stations, down to 15 cm sediment depth. Shelf and upper slope stations exhibited a vertical distribution pattern of ETS activity in the sediment column, different from that of deeper stations. The importance of biological activity measurements as an estimate of productivity is discussed. To prove the thesis that differences in benthic abundance, biomass and activity reflect differences in pelagic surface primary production, in the case of the NW-African coast caused by different upwelling intensities, the values from 35° N were compared with data from 21° N (permanent upwelling activity) and 17° N (ca. 9 months upwelling per year). On the shelf and upper slope (< 500 m) hydrographical conditions (currents, internal waves) influence the deposition of organic matter and cause a biomass minimum between 200 and 400 m depth in some regions. But, in general, macrobenthic abundance and biomass increases with enhanced upwelling activity and reaches a maximum in the area off Cape Blanc (21° N). On the shelf and in the shelf break region meiofauna densities are higher at 35° N in comparison to 21° N; but in contrast to the decreasing meiofauna abundance with increasing water depth at 35° N, an abundance maximum between 400 and 1200 m depth is formed in the Cape Blanc region; this maximum coincides with the maximum of sedimentary chloroplastic pigment equivalents. The comparison of ETS activities between 35° N and 21° N shows on the shelf activity at 21° N is up to 14 times higher and on the slope 4-9 times higher, which demonstrates that benthic activity responds to the surface productivity regime.

Living benthic foraminifers from the central Arctic Ocean

Fifty short sediment cores collected with a multiple corer and five box cores from the central Arctic Ocean were analysed to study the ecology and distribution of benthic foraminifers. To work out living faunal associations, standing stock and diversity, separate analyses of living (Rose Bengal stained) and dead foraminifers were carried out for the sediment surface. The size fractions between 63 and 125 µm and >125 µm were counted separately to allow comparison with former Arctic studies and with studies from the adjacent Norwegian-Greenland Sea, Barents Sea and the North Atlantic Ocean. Benthic foraminiferal associations are mainly controlled by the availability of food, and competition for food, while water mass characteristics, bottom current activity, substrate composition, and water depth are of minor importance. Off Spitsbergen in seasonally ice-free areas, high primary production rates are reflected by high standing stocks, high diversities, and foraminiferal associations (>125 µm) that are similar to those of the Norwegian-Greenland Sea. Generally, in seasonally ice-free areas standing stock and diversity increase with increasing food supply. In the central Arctic Ocean, the oligotrophic permanently ice-covered areas are dominated by epibenthic species. The limited food availability is reflected by very low standing stocks and low diversities. Most of these foraminiferal associations do not correspond to those of the Norwegian-Greenland Sea. The dominant associations include simple agglutinated species such as Sorosphaerae, Placopsilinellae, Komokiacea and Aschemonellae, as well as small calcareous species such as Stetsonia horvathi and Epistominella arctica. Those of the foraminiferal species that usually thrive under seasonally ice-free conditions in middle bathyal to lower bathyal water depth are found under permanently ice-covered conditions in water depths about 1000 m shallower, if present at all.

Geochemical investigations of sediment profiles in the Norwegian-Greenland Sea

High-, i.e. 15-140-yr-resolution climate records from sediment cores 23071, 23074, and PS2644 from the Nordic Seas were used to recon:;truct changes in the surface and deep water circulation during marine isotope stages 1-5.1, i.e. the last 82 000 yr. From this the causal links between the paleoceanographic signals and the Dansgaard-Oeschger events 1-21 revealed in 0180-ice-core records from Greenland were determined. The stratigraphy of the cores is based on the planktic 0180 curves, the minima of which were directly correlated with the GISP2-0180 record, numerous AMS 14C ages, and some ash layers. The planktic d18O and dl3C curves of all three cores reveal numerous meltwater events, the most pronounced of which were assigned to the Heinrich events 1-6. The meltwater events, among other things also accompanied by cold sea surface temperatures and high IRD concentration, correlate with the stadial phases of the Dansgaard-Oeschger cycles and in the western Iceland Sea also to colder periods or abrupt drops in 0180 within a few longer interstadials. Besides being more numerous, the meltwater events also show isotope values lighter in the Iceland Sea than in the central Norwegian Sea, especially if compared to core 23071. This implies a continuous inflow of relative warm Atlantic water into the Norwegian Sea and a cyclonic circulation regime.

Ostracoda in surface sediments of the Arctic Ocean

Ostracodes were studied from deep Arctic Ocean cores obtained during the Arctic 91 expedition of the Polarstern to the Nansen, Amundsen and Makarov Basins, the Lomonosov Ridge, Morris Jesup Rise and Yermak Plateau, in order to investigate their distribution in Arctic Ocean deep water (AODW) and apply these data to paleoceanographic reconstruction of bottom water masses during the Quaternary. Analyses of coretop assemblages from Arctic 91 boxcores indicate the following: ostracodes are common at all depths between 1000 and 4500 m, and species distribution is strongly influenced by water mass characteristics and bathymetry; quantitative analyses comparing Eurasian and Canada Basin assemblages indicate that distinct assemblages inhabit regions east and west of the Lomonosov Ridge, a barrier especially important to species living in lower AODW; deep Eurasian Basin assemblages are more similar to those living in Greenland Sea deep water (GSDW) than those in Canada Basin deep water; two upper AODW assemblages were recognized throughout the Arctic Ocean, one living between 1000 and 1500 m, and the other, having high species diversity, at 1500-3000 m. Downcore quantitative analyses of species' abundances and the squared chord distance coefficient of similarity reveals a distinct series of abundance peaks in key indicator taxa interpreted to signify the following late Quaternary deep water history of the Eurasian Basin. During the Last Glacial Maximum (LGM), a GSDW/AODW assemblage, characteristic of cold, well oxygenated deep water > 3000 m today, inhabited the Lomonosov Ridge to depths as shallow as 1000 m, perhaps indicating the influence of GSDW at mid-depths in the central Arctic Ocean. During Termination 1, a period of high organic productivity associated with a strong inflowing warm North Atlantic layer occurred. During the mid-Holocene, several key faunal events indicate a period of warming and/or enhanced flow between the Canada and Eurasian Basins. A long-term record of ostracode assemblages from kastenlot core PS2200-5 (1073 m water depth) from the Morris Jesup Rise indicates a quasi-cyclic pattern of water mass changes during the last 300 kyr. Interglacial ostracode assemblages corresponding to oxygen isotope stages 1, 5, and 7 indicate rapid changes in dissolved oxygen and productivity during glacial-interglacial transitions.

Determination of heat capacities and thermodynamic properties of 2-(chloromethylthio)benzothiazole by an adiabatic calorimeter

The molar heat capacities of 2-(chloromethylthio)benzothiazole (molecular formula C8H6ClNS2, CA registry no. 28908-00-1) were measured with an adiabatic calorimeter in the temperature range between (80 and 350) K. The construction and procedures of the calorimeter were described in detail. The performance of the calorimetric apparatus was evaluated by heat capacity measurements on alpha-Al2O3. The deviation of experiment heat capacities from the corresponding smoothed values lies within 0.3%, whereas the uncertainty is within +/-0.5%, compared with that of the recommended reference data over the whole experimental temperature range. A fusion transition was found from the C-p-T curve of 2-(chloromethylthio)benzothiazole. The melting temperature and the molar enthalpy and entropy of fusion of the compound were determined to be T-m = (315.11 +/- 0.04) K, Delta(fus)H(m) = (17.02 +/- 0.03) kJ(.)mol(-1), and Delta(fus)S(m) = (54.04 +/- 0.05) J(.)mol(-1.)K(-1), respectively. The thermodynamic functions (H-T - H-298.15) and (S-T - S-298.15) were also derived from the heat capacity data. The molar fraction purity of the 2-(chloromethylthio)benzothiazole sample used in the present calorimetric study was determined to be 99.21 by fraction melting.

Diversity and faunal composition of benthic foraminifera in Hole 44-390A on the Blake Nose Plateau

Benthic foraminiferal assemblages are a widespread tool to understand changes in organic matter flux and bottom-water oxygenation and their relation to paleoceanographic changes in the Upper Cretaceous oceans. In this study, assemblage data (diversity, total number, and number per species and gram) from Deep Sea Drilling Project (DSDP) Site 390 (Blake Nose, western North Atlantic) were processed for the lower Maastrichtian (Globotruncana falsostuarti - Gansserina gansseri Planktic Foraminiferal Zone). These data document significant changes in nutrient flux to the sea floor as well as bottom-water oxygenation during this time interval. Parallel to the observed changes in the benthic foraminiferal assemblages the number of inoceramid shells decreases, reflecting also a significant increase in bottom-water oxygenation. We speculate, that these data could reflect the onset of a shift from warmer low-latitude to cooler high-latitude deep-water sources. This speculation will predate the major reorganization of the oceanic circulation resulting in a circulation mode similar to today at the Early/Late Maastrichtian boundary by ~1 Ma and therefore improves our understanding of Late Cretaceous paleoceanography.

Planktonic foraminifera in the latest Maastrichtian of Walvis Ridge, South Atlantic

An abrupt global warming of 3-4°C occurred near the end of the Maastrichtian at 65.45-65.10 Ma. The environmental effects of this warm event are here documented based on stable isotopes and quantitative analysis of planktonic foraminifera at the South Atlantic DSDP Site 525A. Stable isotopes of individual species mark a rapid increase in temperature and a reduction in the vertical water mass stratification that is accompanied by a decrease in niche habitats, reduced species diversity and/or abundance, smaller species morphologies or dwarfing, and reduced photosymbiotic activity. During the warm event, the relative abundance of a large number of species decreased, including tropical-subtropical affiliated species, whereas typical mid-latitude species retained high abundances. This indicates that climate warming did not create favorable conditions for all tropical-subtropical species at mid-latitudes and did not cause a massive retreat in the local mid-latitude population. A noticeable exception is the ecological generalist Heterohelix dentata Stenestad that dominated during the cool intervals, but significantly decreased during the warm event. However, dwarfing is the most striking response to the abrupt warming and occurred in various species of different morphologies and lineages (e.g. biserial, trochospiral, keeled globotruncanids). Dwarfing is a typical reaction to environmental stress conditions and was likely the result of increased reproduction rates. Similarly, photosymbiotic activity appears to have been reduced significantly during the maximum warming, as indicated by decreased delta13C values. The foraminiferal response to climate change is thus multifaceted resulting in decreased species diversity, decreased species populations, increased competition due to reduced niche habitats, dwarfing and reduced photosymbiotic activity.