Markus Raitzsch

• PhD
• Data Engineer at private company

Most climate proxies of sea surface temperatures suffer from severe limitations when applied to cold temperatures that characterize Arctic environments. These limitations prevent us from constraining uncertainties for some of the most sensitive climate tipping points that can trigger rapid and dramatic global climate change such as Arctic/Polar Amp...

The geological record encodes the relationship between climate and atmospheric carbon dioxide (CO 2 ) over long and short timescales, as well as potential drivers of evolutionary transitions. However, reconstructing CO 2 beyond direct measurements requires the use of paleoproxies and herein lies the challenge, as proxies differ in their assumptions...

A new matrix‐matched reference material has been developed – NFHS‐2‐NP (NIOZ Foraminifera House Standard‐2‐Nano‐Pellet) – with element mass fractions, and isotope ratios resembling that of natural foraminiferal calcium carbonate. A 180–355 µm size fraction of planktic foraminifera was milled to nano‐particles and pressed to pellets. We report refer...

The middle Miocene climate transition ∼ 14 Ma marks a fundamental step towards the current “ice-house” climate, with a ∼ 1 ‰ δ18O increase and a ∼ 1 ‰ transient δ13C rise in the deep ocean, indicating rapid expansion of the East Antarctic Ice Sheet associated with a change in the operation of the global carbon cycle. The variation of atmospheric CO...

seacarbx is a seacarb extension written in R, which enables to use seacarb (Gattuso et al., 2019) for deep-time carbonate system calculations or for culturing studies carried out in seawater with modified [Mg2+] and [Ca2+]. For this, the functions carb, K0, K1, K2, Ks, Kw, Kb, Kspa, and Kspc were modfied to account for the effect of seawater [Mg2+]...

Most studies designed to better understand biomineralization by foraminifera focus mainly on their shell chemistry in order to retrace processes responsible for element uptake and shell formation. Still, shell formation is a combination of not only chemical and biological processes, but is also limited by structural features. Since the processes in...

We reconstruct climate and changes in water-mass properties in relation to variations in palaeoproductivity at the south-western Svalbard margin throughout the last 2000 years. Environmental conditions in subsurface (ca. 250–75 m) and near-surface to surface water (75–0 m) were studied on the basis of the distribution patterns and fluxes of plankti...

The boron isotopic composition (δ11B) of benthic foraminifera provides a valuable tool to reconstruct past deep-water pH. As the abundance of monospecific species might be limited in sediments, microanalytical techniques can help to overcome this problem, but such studies on benthic foraminiferal δ11B are sparse. In addition, microanalytics provide...

The middle Miocene climate transition ~14 Ma marks a fundamental step towards the current "icehouse" climate, with a ~1 ‰ δ 18 O increase and a ~1 ‰ transient δ 13 C rise in the deep ocean, indicating rapid expansion of the East Antarctic Ice Sheet associated with a change in the operation of the global carbon cycle. The variation of atmospheric CO...

The boron isotopic composition (δ 11 B) of benthic foraminifera provides a valuable tool to reconstruct past deep-water pH. As the abundance of monospecific species might be limited in sediments, microanalytical techniques can help to overcome this problem, but such studies on benthic foraminiferal δ 11 B are sparse. In addition, microanalytics pro...

'ScarFace' is a Shiny web application that has been developed to facilitate the usage of the R-package 'seacarb' (http://CRAN.R-project.org/package=seacarb). 'seacarb' is used to calculate the carbonate chemistry of seawater requiring a command-line usage. For non-friends of bare code, 'ScarFace' enables to use 'seacarb' via an user interface (ui)...

Significance Unicellular organisms form endless variability of complex skeletons that serve as archives of Earth’s history and play a crucial role in global geochemical cycles. A longstanding question is how single cells control morphogenesis and mineralization of skeletal structures. Although already addressed by Sir D’Arcy W. Thompson, this probl...

We present a high-resolution record of properties in the subsurface (250–100m), near surface (100–30m) and surface (30–0m) water masses at the SW Svalbard margin in relation to climate changes during the last 2000 years. The study is based on planktic foraminiferal proxies including the distribution patterns of planktic foraminiferal faunas, δ¹⁸O a...

Morphogenesis and biomineralization of polythalamous foraminiferal tests are directly associated with processes of the chamber formation. The main objective of this study is to identify structural components responsible for the test formation. We used fluorescent live imaging applied to juvenile specimens of Amphistegina lessonii d’Orbigny stained...

Actin is a protein that forms one of the main components of the cytoskeleton in eukaryotic cells. This protein as a building block of microfilaments has a crucial role in motility and shaping the cell. Microfilaments are also involved in some modes of intracellular transport. As actin is essential for numerous physiological processes it has been su...

The boron isotopic composition of planktonic foraminiferal shell calcite (δ11BCc) provides valuable information on the pH of ambient water at the time of calcification. Hence, δ11BCc of fossil surface-dwelling planktonic foraminifera can be used to reconstruct ancient aqueous pCO2 if information on a second carbonate system parameter, temperature a...

Aragonitic shells of a hyaline radial foraminifer Hoeglundina elegans consist of a thin top layer and micrometer-scale columnar domains that are regarded as bundled pillars comprising iso-oriented nanograins.

Globothalamean foraminifera (Pawlowski et al., 2013) colonized nearly all marine paleoenvironments, including benthic and planktonic habitats. Their tests are used for biostratigraphic markers and palaeoenvironmental proxies, recently further applied for monitoring studies. Globothalamean tests, like tubothalamean ones, are either agglutinated or s...

In order to fully constrain paleo-carbonate systems, proxies for two out of seven parameters, plus temperature and salinity, are required. The boron isotopic composition (δ11B) of planktonic foraminifera shells is a powerful tool for reconstructing changes in past surface ocean pH. As B(OH)4- is substituted into the biogenic calcite lattice in plac...

In order to fully constrain paleo-carbonate systems, proxies for two out of seven parameters, plus temperature and salinity are required. The boron isotopic composition (δ11B) of planktonic foraminifera shells is a powerful tool to reconstruct changes in past surface ocean pH. As B(OH)4− is substituted into the biogenic calcite lattice in place of...

To examine the sea-surface temperature (SST) evolution during interglacial Marine Isotope Stage (MIS) 11, we compiled a database of 78 SST records from 57 sites. We aligned these records by oxygen-isotope stratigraphy and subjected them to an Empirical Orthogonal Function (EOF) analysis. The principal SST trend (EOF1) reflects a rapid deglacial war...

In field studies of active hydrocarbon seeps the carbon isotopic composition of Rose Bengal stained benthic foraminiferal tests (δ13Ctest) and bottom water DIC (δ13CDIC) deviate from their normal marine ratios. This circumstance led to ongoing discussions on whether aerobic foraminifers like Cibicides wuellerstorfi are capable of living at seepage...

Foraminifera are excellent tracers of palaeoceanographic conditions recorded in their shell (test) morphology and chemical composition. Understanding foraminiferal morphology controlled by chamberwise growth can be reduced to processes of chamber formation. However, little is known about how foraminifera control the shape of the chamber wall to be...

The Marine Isotope Stage (MIS) 11 (424–374 ka) was characterized by a protracted deglaciation and an unusually long climatic optimum. It remains unclear to what degree the climate development during this interglacial reflects the unusually weak orbital forcing or greenhouse gas trends. Previously, arguments about the duration and timing of the MIS1...

The Marine Isotope Stage (MIS) 11 (424-374 ka) was characterized by a protracted deglaciation and an unusually long climatic optimum. It remains unclear to what degree the climate development during this interglacial reflects the unusually weak orbital forcing or greenhouse gas trends. Previously, arguments about the duration and timing of the MIS1...

We present a global compilation of sea-surface temperature (SST) records from marine sediment cores spanning the interval between ~300 and ~500 ka and use this data to investigate the spatial and temporal patterns of surface ocean conditions during MIS 11. Our compilation contains a total of 78 SST records from 57 sites, all associated with plankti...

The boron isotopic composition of seawater (δ11Bsw) is a prerequisite for reliably estimating past variation of seawater pH from boron isotopes in marine carbonates (δ11Bc). Here we compose a 50 m.y. stack of δ11Bc from Atlantic and Pacific Ocean deep-sea sediments, and discuss the potential effects of deep-sea pH and δ11Bsw on our record. Using mo...

The marine isotope stage (MIS) 11 (424–374 ka) was characterized by a protracted deglaciation and an unusually long climatic optimum. It remains unclear to what degree the climate development during this interglacial reflects the unusually weak orbital forcing or greenhouse gas trends. Previously, arguments about the duration and timing of the MIS1...

Laboratory culture experiments were conducted to determine effects of seawater carbonate ion concentration ([CO32-]), and thereby calcite saturation state (Ω), on Mg and Sr incorporation into calcite of two species of shallow-water benthic foraminifera: Ammonia tepida and Heterostegina depressa. Impact on Mg and Sr incorporation by increased seawa...

Incorporation of boron into foraminiferal shells is thought to be primarily governed by the carbonate chemistry of the ambient seawater, suggesting that it can be reconstructed from B/Ca ratios. To this end, B/Ca ratios of the benthic foraminifer Planulina wuellerstorfi from South Atlantic core top samples have been analyzed using laser ablation-in...

Due to its strong gradient in salinity and small temperature gradient the Mediterranean provides an ideal setting to study the impact of salinity on the incorporation of Mg into foraminiferal tests. We have investigated tests of Globorotalia inflata and Globigerina bulloides in plankton tow and core top samples from the Western Mediterranean using...

The ocean plays a major role in the global carbon cycle, and attempts to reconstruct past changes in the marine carbonate system are increasing. The speciation of dissolved uranium is sensitive to variations in carbonate system parameters, and previous studies have shown that this is recorded in the uranium-to-calcium ratio (U/Ca) of the calcite sh...

Laboratory culture experiments were conducted to determine effects of seawater carbonate ion concentration ([CO32-]), and thereby calcite saturation state, on Mg and Sr incorporation into calcite of two species of shallow-water benthic foraminifera: Ammonia tepida and Heterostegina depressa. Impact on Mg and Sr incorporation by increased seawater [...

Boron isotopes (delta11B) in marine carbonates have been evaluated as a proxy for paleoacidity and Plio/Pleistocene estimates of surface and deep ocean pH are consistent with ice core measurements of varying pCO2 and deep ocean carbonate preservation. We have applied this proxy to quantify the extent of deep ocean acidification associated with the...

We investigated the effect of the calcium concentration in seawater and thereby the calcite saturation state (Ω) on the magnesium and strontium incorporation into benthic foraminiferal calcite under laboratory conditions. For this purpose individuals of the shallow-water species Heterostegina depressa (precipitating high-Mg calcite, symbiont-bearin...

We investigated the effect of the calcium concentration in seawater and thereby the calcite saturation state (omega) on the magnesium and strontium incorporation into benthic foraminiferal calcite under laboratory conditions. For this purpose individuals of the shallow-water species Heterostegina depressa (precipitating high-Mg calcite, symbiont-be...

The boron isotopic composition (delta11B) of biogenic and inorganic carbonates is strongly controlled by the pH of the seawater that carbonates precipitate from. Based on this relationship, delta11B in fossil shells of planktic foraminifers is a powerful tool for reconstructing past variations in surface ocean pH. In combination with estimations on...

We investigated the effect of the calcium concentration in seawater and thereby the calcite saturation state (Ω) on the magnesium and strontium incorporation into benthic foraminiferal calcite under laboratory conditions. For this purpose individuals of the shallow-water species Heterostegina depressa (precipitating high-Mg calcite, symbiont-bearin...

We used modern epibenthic foraminifer tests of Cibicidoides mundulus and Planulina wuellerstorfi from South Atlantic core top sediments in order to establish Mg/Ca-temperature relationships for the temperature range from 0 to 15°C. We obtained the following calibrations: Mg/Ca (mmol/mol) = 0.830*exp(0.145*BWT (°C)) for P. wuellerstorfi, and Mg/Ca (...

Mg/Ca ratios in benthic foraminiferal shells are frequently used in paleoceanographic studies to estimate past bottom water temperatures. Apart from temperature, other factors may exert additional influences on foraminiferal Mg/Ca. These include the Mg/Ca ratio of seawater, partial dissolution of shell calcite, salinity, physiological effects, and,...

We used modern epibenthic foraminifer tests of Cibicidoides mundulus and Planulina wuellerstorfi from South Atlantic core top sediments in order to establish Mg/Ca-temperature relationships for the temperature range from 0 to 15°C. We obtained the following calibrations: Mg/Ca (mmol/mol) = 0.830*exp(0.145*BWT (°C)) for P. wuellerstorfi, and Mg/Ca (...

The active continental margin off south-central Chile (36° to 40°S) is transitional between the tectonically erosive, empty-trench margin north of Juan Fernandez Ridge and the accretionary, trench-filled margin south of the Chile Triple Junction. The small width of the presently active accretionary wedge (maximum width of 25 to 50 km) argues for pa...