Oxygen isotope composition of the final chamber of planktic foraminifera provides evidence of vertical migration and depth-integrated growth

The translation of the original seawater signal (i.e. ambient temperature and δ18Osw) into distinct chambers of a single shell of a foraminifer during calcification can influence our interpretation of surface ocean conditions of the past, when based upon oxygen and carbon stable isotope geochemistry. In this study three different hypotheses were tested to gain more insight into biological and ecological processes that influence the resultant composition of stable isotopes of oxygen (δ18O) in the shells of planktonic foraminifera. These hypotheses were related to the shell size; the differences in isotopic composition between the final chamber and the remaining shell; and the differences between different species. Shells of Trilobatus sacculifer, Globigerinoides ruber white and Neogloboquadrina dutertrei were picked from the top of multi-core GS07-150-24, of modern age, offshore of north-eastern Brazil (3∘46.474′ S, 37∘03.849′ W) and analysed for single-shell and single-chamber stable isotope analysis. We show that the mean value of δ18O of the final chambers (δ18OF) is 0.2 ‰ ± 0.4 ‰ (1σ) higher than the mean value δ18O of the test minus the final chamber (δ18O<F) of T. sacculifer. The formation of the final chamber happens at temperatures that are approximately 1 ∘C cooler than the chambers formed prior, suggesting both ontogenetic depth migration to deeper water and a potential offset from the surface signal. Furthermore, we show that there is no statistical difference in the δ18Osacculifer values of shells of three different size classes of T. sacculifer, although the pattern between the different size classes indicates depth migration during the life and growth of T. sacculifer. Comparison of vital effect corrected δ18Oshell between T. sacculifer, G. ruber white and N. dutertrei suggests that G. ruber has a slightly shallower depth habitat (∼90–120 m) compared to the other two species (∼100–130 m). Disentangling depth vs. seasonal habitat is complicated given the commonality between isotope values from similar depths but different seasons; for instance, the same average isotope value will have a shallower depth habitat in May than September. Calculation of seasonal-depth habitat was therefore tested. Our results highlight the complicated nature of interpreting oxygen isotopes even for the modern record.

Oxygen isotope composition of final chamber of planktic foraminifera provides evidence for vertical migration and depth integrated growth

The translation of the original seawater signal (i.e., ambient temperature, salinity and δ18Osw) into distinct chambers of a single shell of a foraminifer during calcification can influence our interpretation of surface ocean conditions of the past, when based upon oxygen and carbon stable isotope geochemistry. Three different hypotheses related to: the size; the composition of the final chamber vs. the remaining shell; and species-specific offsets were tested to gain more insight into biological and ecological processes that influence the resultant composition of stable isotopes of oxygen (δ18O) in the shells of planktonic foraminifera. Shells of Trilobatus sacculifer, Globigerinoides ruber white and Neogloboquadrina dutertrei were picked from the top of the RETRO multi-core GS07-150-24, of Modern age, offshore of North-East Brazil (3°46.474' S, 37°03.849' W) and analysed for single shell and chamber stable isotope analysis. We show that there is a significant difference, of 0.203 ‰ ± 0.40 ‰ (1σ), in δ18O between the final chamber (δ18OF) and the test minus the final chamber (δ18O

On the Taxonomic Identity of the Planktonic Foraminiferal Species Globorotalia Barisanensis Le Roy, 1939

Examination of the holotype of Globorotalia barisanensis Le Roy, 1939, has revealed that this species from the Middle Miocene of central Sumatra is non-keeled, contradicting the synonymizing of G. barisanensis with Globorotalia fohsi. Because the type sample is untraceable, we examined the available type specimens (holotype and eight paratypes), notes and data presented by previous researchers, and material from the near-topotype locality of Paragloborotalia siakensis, to clarify Le Roy's concept of G. barisanensis. Our investigation has revealed that the Middle Miocene of central Sumatra contains two different groups of globorotaliids: the Globorotalia menardii group and the G. fohsi group, and that G. barisanensis belongs to the latter. The paratypes examined belong to Globorotalia peripheroacuta and to forms transitional between G. peripheroacuta and Globorotalia praefohsi. The holotype, as described by Le Roy, is included in G. peripheroacuta as well, despite the observation that it differs from the paratypes in the abnormally inflated final chamber. In retrospect, the specimen selected as the holotype was an unfortunate choice as it has long been misinterpreted and used to denominate the earliest representatives of the G. fohsi group (viz. G. fohsi barisanensis) until G. barisanensis was reinterpreted as a junior synonym of G. fohsi based on a flawed redrawing of a fully keeled holotype of G. barisanensis. We conclude that Le Roy's concept of G. barisanensis was broad and may have included G. fohsi and Globorotalia peripheroronda as well. Remarkably, after 67 years of misinterpretation since Bolli (1950), G. barisanensis appears to be a valid name and a senior synonym of G. peripheroacuta. However, we recommend that it will be more practical to conserve the latter name, which is well established in the literature.

Results with a Multi Stage System of Filtration Employing a Cyclone

The development of a new prototype multi stage filter was described at TMS 2008 in which a ceramic foam filter was applied in a first chamber operating in cake mode; grain refiner added in a second chamber and a cyclone deployed in a final chamber to ensure removal of any oxides or agglomerates arising from the grain refiner addition or release events from the foam filter. The first industrial prototype was installed at Trimet Aluminium at Essen in Germany and demonstrated that liquid metal could pass through the cyclone successfully without excessive turbulence or splash. The further development of the prototype based on new water modeling work is described.

Clone culture studies of a new rosalinid foraminifer from Plymouth, England and Wellington, New Zealand

A formal description of Rosalina leei sp.nov. (Foraminifera) includes an account of the great morphological variation found among adult agamonts obtained over a period of 14 months from clone cultures. Variation in chamber number, direction of coiling, overall shape, the degree of inflation of the final chamber and suture characters are detailed.