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(Appendix A) Radiolarian abundances in ODP Hole 175-1084A

<p>The changing composition of radiolarian faunas from late Neogene deep-sea sediments has been used in recent years as a proxy for changes in marine paleoproductivity. We examine radiolarian faunas, organic carbon content (TOC), opal and coarse-fraction components over the last 270,000 years in sediments from ODP Hole 1084A, drilled in a high productivity upwelling region within the Benguela Upwelling System off the west coast of Africa. Age control is provided by stable oxygen isotope measurements of benthic foraminifera. Prior research has established that late Pleistocene glacial intervals in this upwelling system generally had higher productivity than interglacials. The radiolarian WADE (water-depth ecology) paleoproductivity index correlates well with TOC and opal in these samples, and all three parameters change in synchrony with the benthic isotope curve over all but the MIS 5e–6 time interval. WADE inferred productivity is significantly higher in glacials than interglacials. We conclude that the WADE index is a useful proxy for paleoproductivity at this location, as are also opal and organic carbon accumulation rates. Carbonate and carbonate based indices such as the accumulation rate of benthic foraminifera (BFAR) by contrast do not correlate well either to productivity indices or to the glacial–interglacial cycle, and are interpreted to primarily reflect carbonate dissolution.</p>

Schwerpunktprogramm (SPP) 527: Bereich Infrastruktur - International Ocean Discovery Program, Teilprojekt: Terrestrische Ökosystem- und Klimadynamik in SE-Afrika für den Zeitraum der Entwicklung, des Vorkommens und des Aussterbens archaischer Hominiden (4-2 Ma) basierend auf Kernmaterial von IODP-Expedition 361

Das beantragte Projekt hat zum Ziel, die terrestrische Ökosystem- und Klimadynamik - und damit die naturräumlichen Rahmenbedingungen für die Evolution früher Hominiden - in SE-Afrika während des 'mittleren' Pliozäns und frühen Pleistozäns zu rekonstruieren. Um dieses Ziel zu erreichen, soll an Hand von Kernmaterial von IODP Expedition 361 ('Southern African Climates') eine Land/Meer-Korrelation vor SE-Afrika erarbeitet werden; diese wird die erste kontinuierliche Rekonstruktion der terrestrischen Ökosystem- und Klimaänderungen in SE-Afrika während des 'mittleren' Pliozäns bis frühen Pleistozäns liefern. Methodisch basiert das Projekt auf einem integrierten Ansatz, der palynologische (Pollen und Sporen) und elementgeochemische (XRF-Scanning) Analysen vereint und auf den Splice von IODP-Site U1478 (Straße von Mosambik) angewendet werden soll. Eine präzise Alterskontrolle wird durch die hochauflösende Benthos-Sauerstoffisotopenstratigraphie ermöglicht, die aktuell für Site U1478 erarbeitet wird. Site U1478 ist für die hier vorgeschlagenen Untersuchungen aus einer Reihe von Gründen ideal geeignet: (i) er stellt ein stratigraphisch außergewöhnlich vollständiges Archiv dar und verfügt dabei über hohe Sedimentationsraten; (ii) seine proximale Lage in Bezug auf das Limpopo-Delta gewährleistet einen hohen Anteil terrigenen Inputs im Kernmaterial; (iii) die Ursprungsregion dieser terrigenen Komponenten lässt sich hervorragend eingrenzen; (iv) er ist gegenüber terrestrischen Klimaänderungen hoch empfindlich, wie frühere Studien an nahe gelegenen Kurzkernen belegen; (v) die für das vorgeschlagene Projekt durchgeführten Pilotstudien an Kernfänger-Material belegen, dass seine Sedimente in Bezug auf Pollen und Sporen extrem produktiv sind; er liegt in einer proximal Position hinsichtlich der paläoanthropologischen 'Cradle of Humankind'-Fundstätten in Südafrika. Unter Berücksichtigung des gegenwärtigen Forschungsstandes zur Evolution archaischer Hominiden (insbesondere Australopithecus africanus) fokussiert das Projekt auf den Zeitraum zwischen 4 und 2 Ma; kritische Intervalle der Evolution archaischer Hominiden sollen in besonders hoher zeitlicher Auflösung analysiert werden. Die Integration der palynologischen und elementgeochemischen Proxy-Daten wird detaillierte Aussagen zum Charakter und Zeitpunkt wie auch zur Stärke und Geschwindigkeit der Ökosystem- und Klimavariabilität im Einzugsgebiet des Limpopo River und damit in der 'Cradle of Humankind'-Region erlauben. Dadurch wird nicht nur die Klärung der Frage möglich, inwiefern Intervalle mit besonders ausgeprägtem Umweltwandel tatsächlich mit Schritten in der Hominiden-Evolution einhergehen, sondern es lassen sich auch die einzelnen Komponenten dieses Umweltwandels identifizieren. Diese Informationen können neues Licht auf die aktuelle Diskussion um potenzielle kausale Zusammenhänge zwischen Umwelt-'Forcing' und menschlicher Evolution werfen.

Modeled environmental data-layers and changes predicted under RCP2.6, 4.5 and 8.5 for the deep Atlantic Ocean

The data layers provided show current values for seawater temperature, pH, calcite and aragonite saturation (%), oxygen concentration, and particulate organic carbon (POC) flux to the seafloor at different depths (500, 1000, 2000, 3000, and 4000m) at the present day (1951-2000) and changes in these variables expected between 2041-2060 and 2081-2100 under different RCP scenarios. The data layers were generated following the methods described in Levin et al. (2020). In short, in 2019, we obtained the present day and future ocean projections for the different years which were compiled from all available data generated by Earth Systems Models as part of the Coupled Model Inter-comparison Project Phase 5 (CMIP5) to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Three Earth System Models, including GFDL‐ESM‐2G, IPSL‐CM5A‐MR, and MPI‐ESM‐MR were collected and multi-model averages of temperature, pH, O2 , export production at 100-m depth (epc100), carbonate ion concentration (co3), and carbonate ion concentration for seawater in equilibrium with aragonite (co3satarg) and calcite (co3satcalc) were calculated. The epc100 was converted to export POC flux at the seafloor using the Martin curve (Martin et al., 1987) following the equation: POC flux = export production*(depth/export depth)0.858. The export depth was set to 100 m, and the water depth using the ETOPO1 Global Relief Model (Amante and Eakins, 2008). Seafloor aragonite and calcite saturation were computed by dividing co3 by co3satarg and co3satcalc. All variableswere reported as the inter-annual mean projections between 1951-2000, 2041-2060, and 2081-2100. The data for calcite and aragonite saturation can be found in Morato et al. (2020).

The influence of seawater pH on U/ Ca ratios in the scleractinian cold-water coral Lophelia pertusa

The increasing pCO2 in seawater is a serious threat for marine calcifiers and alters the biogeochemistry of the ocean. Therefore, the reconstruction of past-seawater properties and their impact on marine ecosystems is an important way to investigate the underlying mechanisms and to better constrain the effects of possible changes in the future ocean. Cold-water coral (CWC) ecosystems are biodiversity hotspots. Living close to aragonite undersaturation, these corals serve as living laboratories as well as archives to reconstruct the boundary conditions of their calcification under the carbonate system of the ocean. We investigated the reef-building CWC Lophelia pertusa as a recorder of intermediate ocean seawater pH. This species-specific field calibration is based on a unique sample set of live in situ collected L. pertusa and corresponding seawater samples. These data demonstrate that uranium speciation and skeletal incorporation for azooxanthellate scleractinian CWCs is pH dependent and can be reconstructed with an uncertainty of ±0.15. Our Lophelia U / Ca-pH calibration appears to be controlled by the high pH values and thus highlighting the need for future coral and seawater sampling to refine this relationship. However, this study recommends L. pertusa as a new archive for the reconstruction of intermediate water mass pH and hence may help to constrain tipping points for ecosystem dynamics and evolutionary characteristics in a changing ocean.

Seawater carbonate chemistry and behavioural trait expression of polar invertebrates

Here, we examine the ecosystem ramifications of changes in sediment-dwelling invertebrate bioturbation behaviour—a key process mediating nutrient cycling—associated with nearfuture environmental conditions (+ 1.5 °C, 550 ppm [pCO2]) for species from polar regions experiencing rapid rates of climate change. This dataset is included in the OA-ICC data compilation maintained in the framework of the IAEA Ocean Acidification International Coordination Centre (see https://oa-icc.ipsl.fr). Original data were downloaded from Polar Data Centre (see Source) by the OA-ICC data curator. In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2024) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2024-07-11.

Global particulate organic carbon flux derived from Th-234: 13 ocean regions, 3 export depths

The 234Th–238U disequilibrium technique has been widely used to estimate the amount of particulate organic carbon (POC) exported from surface ocean layers to the deep sea. This method is based on determining 234Th fluxes from vertical 234Th–238U profiles in the water column and converting them into POC fluxes using POC/234Th ratios measured in sinking particles at a given calculation depth. We present here an extensive repository of POC fluxes, together with Th fluxes and POC/234Th ratios. Covering all the global ocean, classified in 13 regions, season and moment of the bloom and calculated at three different depths: i) a fixed depth (100 m) ii) the reference depth in the paper associated to the base of the euphotic zone iii) the 234Th–238U equilibrium depth. To ensure a compilation representative of the global ocean, the dataset were selected using the division areas proposed by the international network JETZON (Joint Exploration of the Twilight Zone Ocean Network); that agreed a division of the oceans in 13 regions based on their contrasted physics and biogeochemical characteristics. The stations from 234Th publications associated to each JETZON region were carefully selected according to their ability to represent regional environmental conditions. Furthermore, station selection was based on essential criteria such as data quality and accessibility, availability of time series, clear definition of export depth, measurements from established programs, e.g. GEOTRACES, and the presence of other additional relevant ancillary data. The data in the compilation are thus organized by region and include geographic coordinates, season, selected export depth, and other key factors (such as a description of the flux evaluation depth or the export depth zone). After 234Th–238U compilation, 234Th fluxes were calculated, when possible, at the three different depths, i), ii) and iii), under the assumption of steady-state conditions, following Le Moigne et al. 2013. Using POC/234Th ratios, POC fluxes are estimated from Th fluxes and both fluxes were included in the repository. POC/234Th ratios were chosen from pump samples, prioritizing particles larger than 53 μm when available. These ratios must be estimated at the flux calculation depth [i), ii) and iii)]. When they were not available at the calculation depth POC/234Th values were interpolated as described in the readme text file. The values of the ratios are included in the repository, specifying the depth at which they were determined and indicating whether they have been interpolated. Similarly, when 234Th, 238U concentrations were not available at the calculation depth, values were interpolated (see readme text file).

Mean Deep Ocean volume-weighted stacks

Mean Deep Ocean stacked records weighted by ocean basin volume are also provided for: benthic δ18O, MDOT and δ18Oseawater and compiled from records described for the non-weighted stacks. The weighted stacks were created using basin weights defined using fixed deep ocean volume fractions following the volumetric approach of Lisiecki and Stern (2016) (see their Table S2), and renormalised to unity at each time step to reflect the ocean volume represented by the available records.

Atlantic, Pacific and Mean Deep Ocean temperature and δ¹⁸Oseawater stacks

Stacked deep-water (>2500m) deconvolved benthic Mg/Ca–δ18O records spanning the past 1.5 Myr for: the North Atlantic comprising IODP Site U1385 [Uvigerina peregrina and Globobulimina affinis] and DSDP Site 607 [Cibicidoides wuellerstorfi, Oridorsalis umbonatus, and Uvigerina spp.] (Sosdian and Rosenthal, 2009; Ford et al., 2016); the Pacific incorporating ODP Sites 1123 [Uvigerina spp.] (Elderfield et al., 2012) and Site 1208 [Uvigerina spp.] (Ford and Raymo, 2020); and, Mean Deep Oceans including all of the above plus ODP Site 1094 [Melonis pompilioides] (Hasenfratz et al., 2019). To investigate changes in abyssal ocean density stratification across the Middle Pleistocene Transition estimates of deep-water temperature and δ18Oseawater were generated with error propagation using PSU Solver in MATLAB (Thirumalai, Quinn and Marino, 2016). PSU Solver-derived δ18O, temperature and δ18Oseawater records for each site were interpolated on a 3 kyr interval and bootstrapped. Stacks were manually created by first identifying gaps in each site's original data and then averaging the means and errors across each age interval.

4.5 million years of deep ocean carbon isotope gradients and trace metals redox data

This dataset contains a 4.5 million year record of the benthic stable carbon isotope gradient between Ocean Drilling Program Sites 982 and 807 and a long trace metals dataset from ODP Site 1208. In addition, we include compiled timeslice data from throughout the deep ocean that characterize the stable carbon isotope difference between benthic stable isotope composition of C. wuellerstorfi at Site 982 and that site.

Schwerpunktprogramm (SPP) 527: Bereich Infrastruktur - International Ocean Discovery Program, Teilprojekt: Sauerstoffentzug im Pazifischen Ozean während des Pliozäns

Der Sauerstoffgehalt der Weltozeane ist notwendig zum Überleben der meisten Organismen und seine Abnahme hat damit einen enormen wirtschaftlichen Einfluss. Weil sich das globale Klima weiter ändert, werden nicht nur die Meere immer wärmer wodurch sie immer weniger Sauerstoff aufnehmen können, auch werden immer mehr Nährstoffe von den Kontinenten in den Meere gespült so dass viele Küstenregionen immer mehr Sauerstoff verlieren. Um den Einfluss des abnehmenden Sauerstoffgehalts auf marine Ökosysteme besser zu verstehen, brauchen wir Rekonstruktionen aus der Vergangenheit um zu verstehen was genau in der Zukunft passieren wird. Foraminiferen sind der ideale 'Proxy' um diese Änderungen zu rekonstruieren, weil sie nicht nur unter niedrigen Sauerstoffbedingungen überleben können sondern sogar auch weiter kalzifizieren, was notwendig ist um die Geochemie der Schalen zu nutzen. Während der Kalzifizierung werden z.B. redox-empfindliche Elemente wie Mangan in den Schalen eingebaut, was als Hinweis für frühere Sauerstoffbedingungen genutzt werden kann. Mit diesem Antrag plane ich, Mn/Ca in Foraminiferen zu nutzen, um zu zeigen wie der Pazifik im späten Pliozän den Großteil seinem Sauerstoffs verloren hat und damit seinen heutigen sauerstoffarmen Zustand erreichte. In diesem Projekt werde ich die nachfolgenden Hypothesen prüfen; zum ersten dass der Pazifik sein Sauerstoffgehalt innerhalb kürzester Zeit, nach dem Beginn der Nordhemisphären Vereisung (ca. 2.7 Ma), durch Wassermassenstratifizierung im Nordpazifik verloren hat; zweitens dass die Stratifizierung im Nordpazifik während des M2-Glazial (ca. 3.3 Ma) für die Abnahme des Sauerstoffgehalts des gesamten Pazifiks verantwortlich war; und drittens dass sich der Sauerstoffgehalt des Pazifik während der ersten Interglaziale (ca. 2.5 Ma) nach dem Beginn der Nordhemisphäre Vereisung zeitweise erholte.

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