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The distribution of planktonic foraminiferal species in two cores, ENAM 30 and ENAM 94-13, taken within the framework of the European North Atlantic Margin (ENAM) project from water depths of around 1200 m, south-west of the Faeroe Islands, were investigated. The oxygen isotope record of the polar Neogloboquadrina pachyderma sinistral includes Oxygen Isotope Stages (OIS) 4 to OIS 1 in core ENAM 30, whereas that of core ENAM 94-13 precedes the OIS 6/7 boundary. The age of the sediments is based on AMS 14C measurements. The micropaleontological record suggests much more variable hydrographic conditions during OIS 7 to OIS 3, compared to the more stable OIS 2 and OIS 1. Trends of dramatic warming through glacial-interglacial boundaries are followed by a general trend of decreasing temperatures towards the end of interglacial stages. This implies that colder episodes could also develop in the near future of the Holocene at a sub-Milankovitch time scale, after the end of the recent warming phase. The oxygen and carbon isotopic signal of the sub-polar species N. pachyderma dextral, Turborotalita quinqueloba and Globigerina bulloides, from deglacial, interglacial and interstadial sediments, were analyzed for comparison with the signal of N. pachyderma sinistral. Our investigation shows that the low relative abundance of the polar morphotype of N. pachyderma in sediments from warmer climates can yield an isotopic signal that does not correspond to the prevailing climatic conditions of the area at the time slice studied, probably for not being the most representative species of the sample. This fact is further supported by the older AMS 14C age of N. pachyderma, compared to the ages of the sub-polar species from the same level. The signals of the three sub-polar species, on the other hand, show a more coherent trend in the intervals investigated and may reflect better the actual environmental conditions. Warm climatic episodes within Oxygen Isotope Stage 6, indicated by the high relative abundance of sub-polar species, were not apparent in the oxygen isotope record of N. pachyderma sinistral, while the lower values of the isotopic records of the sub-polar species accurately reflect these warmer intervals.

The intra-species variability of magnesium in calcitic tests of the planktic foraminifer Neogloboquadrina pachyderma sinistral, its relationship to water temperature, salinity and diagenesis, and its potential for paleoceanographic interpretations are investigated. Core-top samples from high northern and southern latitudes and long sediment cores from the Norwegian Sea are investigated for their Recent foraminiferal magnesium content and the variability of magnesium during the past approximately 180,000 years. The quantitative measurement of magnesium was performed by electronmicroprobe analysis. Sample contamination as well as the influence of early diagenetic processes, potentially altering the original element content, can be ruled out for the samples and the time period considered here. Magnesium concentrations in N. pachyderma sinistral are generally lower than published concentrations within other species. Moreover, the foraminiferal tests appear to be undersaturated with respect to magnesium for the water temperatures they have exper i e n c e d . Magnesium concentrations in Recent N. pachyderma sinistral covary most closely with surface water temperature. Salinity changes are of minor importance. Downcore magnesium variations covering the last climatic changes correlate to sedimentological and geochemical parameters. In general, relatively high magnesium concentrations appear during interglacials, whereas low magnesium concentrations occur during glacial periods. Even short climatic events, such as the Younger Dryas cooling, are reflected in the magnesium signal. It is therefore suggested that magnesium in foraminiferal tests reflects relative water temperature variations even at high latitudes, and thus may serve as a paleoceanographic tool to reconstruct changes in surface water circulation.

The pelagic foraminifer Neogloboquadrina pachyderma (Ehrenberg, 1861) occurs in new ice, congelation ice, and the underlying water column of the Weddell Sea. Neogloboquadrina pachyderma is incorporated into the ice in large numbers at the time of its formation. The average number of foraminifers per liter of ice was 87 and numbers ranged between 0 and 1,075. Sea ice contained 70 times more foraminifers per unit volume than the underlying water column and on an areal basis the sea ice cover has approximately the same number of specimens as 60 m of underlying water column. The foraminifera are usually incorporated into the ice when it is being formed dynamically and are thus subsequently associated mainly with granular ice. Many foraminifers are able to survive and grow in the ice where algal biomass in winter is high compared to the water column, perhaps indicating an overwintering strategy. Arctic sea ice, on the other hand, is practically devoid of foraminifers. These observations may have implications for paleoceanographers who use N. pachyderma as a tool to reconstruct past surface water conditions.

Pliocene and lower Pleistocene dextral and sinistral forms referred to Globorotalia pseudopachyderma, paleoclimatic indicator

Juvenile specimens associated with diatom community, probably Globigerina pachyderma or G. quinqueloba

Twenty-five taxa (Turborotalia quinqueloba lingulata n. ssp.) described, taxonomic revisions, "Globigerina" pachyderma referred to Neogloboquadrina, Turborotalia name restricted, correlation of New Zealand stages with global biostratigraphic zones

Both forms have self-contained histories and are separate species, distribution, the two populations (left-coiling and right-coiling) appear to be mutually exclusive