Gerhard Schmiedl

Hamburg University | UHH · Department for Earth System Sciences

Recurrent deposition of organic-rich sediment layers (sapropels) in the eastern Mediterranean Sea is caused by complex interactions between climatic and biogeochemical processes. Disentangling these influences is therefore important for Mediterranean palaeo-studies in particular, and for understanding ocean feedback processes in general. Crucially,...

We have determined stable carbon isotope ratios of epifaunal and shallow infaunal benthic foraminifera to relate the inferred gradient of pore water δ13CDIC to varying trophic conditions, and to test the potential of developing a transfer function for organic matter flux rates. The data set is based on samples retrieved from a well-defined bathymet...

North Africa experienced dramatic changes in hydrology and vegetation during the late Quaternary driven by insolation-induced shifts of the tropical rain belt and further modulated by millennial-scale droughts and vegetation-climate feedbacks. While most past proxy and modelling studies concentrated on the temporal and spatial dynamics of the last...

A total of 288 modern benthic carbonate shelf foraminifera in three areas of the Western Mediterranean Sea (Alboran Platform, Oran Bight and the southwest shelf of Mallorca) have been studied and are systematically listed. This systematic description provides a list of synonyms, short remarks about morphological features of the taxa and some annota...

Lateglacial and Holocene faunal and stable-isotope records from benthic foraminifers in the eastern Mediterranean Sea (EMS) suggest a high spatiotemporal variability of deep-water oxygenation and biogeochemical processes at the sea floor during that time. Changes in the oxygenation and food availability of the deep-sea ecosystems are closely linked...

We present results of simulations performed with a physical–biogeochemical ocean model of the Mediterranean Sea for the Last Glacial Maximum (LGM) and analyse the differences in physical and biochemical states between the historical period and the LGM. Long-term simulations with an Earth system model based on ice sheet reconstructions provide the n...

In this study, we present the first well-dated, high-resolution alkenone-based sea surface temperature (SST) record (SL167) from the northeastern Oman Margin (Gulf of Oman) in the northwestern Arabian Sea. The SST reconstructions spanning the last 43 kyr reveal fluctuations of approximately 7 °C (20.1 °C to 27.4 °C) and demonstrate a higher sensiti...

Changing climatic conditions can shape the strength and extent of the oxygen minimum zone (OMZ). The presence and variability of the OMZ in the Arabian Sea is of importance to the latter's ecosystem. The state of oxygenation has, for instance, an impact on the pelagic and benthic faunal community or the nitrogen and carbon cycles. It is important t...

The Island of Rhodes, located in the Eastern Mediterranean Sea, is affected by an active convergent plate boundary. In this context, marine sediments of Plio-Pleistocene age have been uplifted and are outcropping along the eastern coast of Rhodes. These archives provide an excellent opportunity to unravel the hydrological and climatic changes of th...

We present results of simulations with a physical-biogeochemical ocean model of the Mediterranean Sea for the last glacial maximum (LGM) and analyse the difference in physical and biochemical states between the present day and the past. Long-term simulations with an Earth system model based on ice sheet reconstructions provide the necessary atmosph...

The oceanography of the Red Sea is controlled by the restricted exchange of water masses with the Indian Ocean and by high evaporation rates due to the arid climate of the surrounding land areas. In the northern Red Sea, the formation of oxygen-rich subsurface water ventilates the deeper parts of the basin, but little is known about the variability...

Climatic and associated hydrological changes controlled the transport processes and composition of the sediments in the central Red Sea during the last ca. 200 kyr. Three different source areas for mineral dust are identified. The dominant source is located in the eastern Sahara (Sudan and southernmost Egypt). We identify its imprint on Red Sea sed...

Multiperspektivische Blicke auf ein Jahrhundert Gelehrsamkeit. Anlass für diese mehrbändige Publikation, die sich der Komplexität von Universität multiperspektivisch nähert, sind 100 Jahre Hamburger Universitätsgeschichte. Nach Band 1 zu allgemeinen Aspekten und Entwicklungen (2020) enthalten die Bände 2 (2021), 3 (2022) und 4 (2023) Beiträge zu ei...

Benthic foraminifera have rarely been reported from saline springs in Germany. To fill this gap, we investigated live (Rose Bengal stained) and dead benthic foraminifera from saline ponds, springs, and meadows in central Germany. For foraminiferal investigations, we collected surface samples along transects with changes in vegetation at Sülldorf in...

The island of Rhodes in the eastern Mediterranean Sea is situated in an area affected by an ongoing plate convergence, and its Pleistocene marine environments were influenced by recurring hypoxia and changes in organic matter fluxes. This makes the island an important site to study the influence of orbital-driven climate changes and tectonic-induce...

Benthic foraminifera have rarely been reported from saline springs in Germany. To fill this gap, we investigated live (Rose Bengal stained) and dead benthic foraminifera from saline ponds, springs, and meadows in central Germany. For foraminiferal investigations, we collected surface samples along transects with changes in vegetation at Sülldorf in...

Climatic conditions and its change shape the strength and extent of the oxygen minimum zone (OMZ). The presence and variability of the OMZ in the Arabian Sea is of importance for their ecosystem. The state of oxygenation has, for instance, an impact on the pelagic and benthic faunal community or the nitrogen and carbon cycles. The understanding of...

Eutrophication is accelerating the recent expansion of oxygen-depleted coastal marine environments. Several bolivinid foraminifera are abundant in these oxygen-depleted settings, and take up nitrate through the pores in their shells for denitrification. This makes their pore density a possible nitrate proxy. This study documents three aspects relat...

Tidal wetlands are highly dynamic ecosystems that are susceptible to changes in sea level and flooding from storm surges. Among them, salt marshes play a key role in coastal protection as they contribute to wave attenuation through their regulating ecosystem services, thereby promoting sediment deposition and shoreline stabilization. However, the r...

The oceanography of the Red Sea is controlled by the restricted exchange of water masses with the Indian Ocean and by high evaporation rates due to the arid climate of the surrounding land areas. In the northern Red Sea, the formation of oxygen-rich subsurface waters ventilates the deeper parts of the basin, but little is known about the variabilit...

Benthic foraminifera assemblages can be used to trace trophic conditions and oxygen levels at the seafloor during the Early-Middle Pleistocene Transition (EMPT, 700-1250 kyr). The EMPT was an event that marked a change in how Earth's climate system responded to orbital forcing. Throughout the EMPT, the frequency of glacial-interglacial cycles shift...

Climatic and associated hydrological changes controlled the transport processes and composition of the sediments in the central Red Sea during the last ca. 200 kyr. Three different source areas for mineral dust are identified. The dominant source is located in the eastern Sahara (Sudan and southernmost Egypt). We identify its imprint on Red Sea sed...

A case study of micro-computed tomography for the destruction-free assessment of fossils in sediments is described.

Human activities in coastal areas have intensified over the last 200 years, impacting also high-latitude regions such as the Baltic Sea. Benthic foraminifera, protists often with calcite shells (tests), are typically well preserved in marine sediments and known to record past bottom-water conditions. Morphological analyses of marine shells acquired...

There is growing concern on the survival of Mediterranean forests under the projected near-future droughts as a result of anthropogenic climate change. Here we determine the resilience of Mediterranean forests across the entire range of climatic boundary conditions realized during the past 500 kyrs based on continuous pollen and geochemical records...

Analysis of benthic foraminifera assemblages from the Gulf of Cadiz reveal a considerable change in the abiotic factors such as oxygen levels and trophic conditions during the Early-Middle Pleistocene Transition (EMPT, 700-1250 kyr). The EMPT was a global climate event and characterized by a drastic change in the deep thermohaline circulation that...

Surface benthic foraminiferal assemblages associated with cold‐water coral mounds and reefs from the Irish margin and Norwegian shelf (North‐east Atlantic) are for the first time compared quantitatively. Results indicate that the considered sites share a common assemblage, dominated by elevated epibenthic and distinct infaunal species. This surface...

The African monsoon system controlled the mobilisation and delivery of clay-sized sediment particles to the Eastern Mediterranean Sea in the late Quaternary. During African Humid Periods of the last 200 kyr, smectite-rich suspension load was provided by the Nile river and by palaeo-rivers discharging into the Gulf of Sirte. After the termination of...

For the past 200 years, estuarine environments experienced intense and rapid environmental degradations due to human interventions. In addition, Global Changes are modifying the estuarine physiography, leading to a re-structuration of marginal marine benthic communities. The aim of this study is to document, the modern assemblage composition and th...

Oxygen Minimum Zones (OMZs) are expanding in modern oceans due to anthropogenically-driven climate and environmental change. In the Eastern Mediterranean Sea (EMS), OMZs developed in the early Holocene as a result of decreased intermediate water ventilation, increasing temperature, and increased Nile discharge and primary productivity. Here, we rep...

Intertidal coastal wetlands are regularly exposed to storm surges and associated flooding, resulting in the recurrent accretion of reworked sediments on the salt-marsh surfaces. In this context, well-stratified salt-marsh sediment sequences provide an exceptional archive to evaluate the response of coastal wetlands to past storm-climate variability...

Negative excursions in the stable carbon isotopic composition (δ¹³C) at Atlantic intermediate to mid‐depths are common features of millennial‐scale events named Heinrich Stadials. The mechanisms behind these excursions are not yet fully understood, but most hypotheses agree on the central role played by the weakening of the Atlantic meridional over...

Benthic foraminifera are sensitive to environmental changes and widely used as tools to monitor pollution. Rising numbers of deformed tests are often used as indicator for elevated levels of heavy metals, but little is known about the relation between heavy metal incorporation into foraminiferal tests and the formation of test deformities. Here, tw...

Estuaries are transitional ecotones influenced by both marine and terrestrial (fresh) waters. For the past 200 years, estuarine environments experienced intense and rapid environmental degradations due to anthropic action (e.g., urban sewage, industry, aquaculture, and agricultural runoff). The distribution of benthic foraminifera in estuarine area...

Pollen of middle Oligocene to early Miocene age from core sediments from the New Jersey Shallow Shelf (Atlantic Coastal Plain: IODP-Expedition 313, Site M0027A), was analyzed using light- and scanning electron microscopy, and a pollen-based bioclimatic analysis was performed. The microflora is dominated by Quercus pollen. Pollen ornamentations indi...

Endmember modelling on the terrigenous silt fraction of nine marine sediment cores spanning up to 180,000 years reveals the influx of North African dust into the Eastern Mediterranean Sea. The dust grain size modes decrease with transport distance, from >50 µm off the African coast to ca. 30 µm in the Aegean Sea. The dust signal is strongly influen...

In the Eastern Mediterranean Sea (EMS), natural climate-driven changes that impacted its physical circulation and created deep-water anoxia have led to periods of distinctive deposits referred to as sapropels. The most recent sapropel event (S1) occurred between ~6-10 kyr BP. Use of a global climate model has suggested that there was a previously u...

Carbon is one of the key elements in organisms and non-living compounds on Earth. Carbon dioxide and methane are important greenhouse gases in the atmosphere, dissolved inorganic (DIC) and organic carbon (DOC) determine water biogeochemistry, and carbonates are major constituents of marine sediments. Stable carbon isotope ratios (¹³C/¹²C), expresse...

We have studied benthic foraminiferal assemblages in a marine sediment section (Pefka E section) from the Lindos Bay Formation deposited during the early Pleistocene to provide new insights into the paleo-ecologic and neotectonic evolution of the SE part of the island of Rhodes (NE Mediterranean Sea). Relatively high amounts of eutrophic/low oxygen...

Salt marshes and other blue carbon ecosystems have been increasingly recognized for their carbon (C)‐sink function. Yet, an improved assessment of organic carbon (OC) stocks and C‐sequestration rates is still required to include blue C in C‐crediting programs. Particularly, factors inducing variability in the permanence of sequestration and allocht...

This data set contains census counts of Early Pleistocene benthic foraminifera on species level (fraction >125 µm) from a Lindos Bay Clay deposit in SE Rhodes. Census counts on genus level of the >125 and >150 µm fractions from the same samples can be found under https://doi.org/10.1594/PANGAEA.884573.

Salt-marsh sediments of the southeastern North Sea provide an archive to unravel the influences of coastal management and natural processes such as storm-tide deposition on salt-marsh development. We present a record of salt-marsh evolution during the past century from the Bay of Tümlau (northwestern Germany) based on fossil foraminiferal assemblag...

As a natural sediment trap, the marine sediments of the sheltered central part of the Maldives Inner Sea represent an exceptional archive for paleoenvironmental and climate changes in the equatorial Indian Ocean. Our multi-proxy data record reveals an enhanced dust supply during the glacial intervals, causing elevated Br XRF counts and Fe/Al ratios...

The iconic climate archive of Tenaghi Philippon (TP), NE Greece, allows the study of short-term palaeoclimatic and environmental change throughout the past 1.3 Ma. To provide high-quality age control for detailed palaeoclimate reconstructions based on the TP archive, (crypto)tephra studies of a peat core ‘TP-2005’ have been carried out for the 0–13...

We present the first tephroanalysis based on geochemical fingerprinting of volcanic glass shards from eastern Apulian shelf sediments in the Gulf of Taranto (Italy). High sedimentation rates in the gulf are ideal for high-resolution paleoclimate studies, which rely on accurate age models. Cryptotephrostratigraphy is a novel tool for the age assessm...

A 12 m long sediment sequence was recovered from the eastern Dendi Crater lake, located on the central Ethiopian Plateau and in the region of the Blue Nile headwaters. 24 AMS radiocarbon dates from bulk organic carbon samples indicate that the sediment sequence spans the last ca. 12 cal kyr BP. Sedimentological and geochemical data from the sedimen...

Mid-Oligocene to Early Miocene terrestrial palynomorphs from the New Jersey hinterland (eastern North America: IODP-Expedition 313) were analysed, using light microscopy and scanning electron microscopy, to infer altitudinal spatial and long-term temporal vegetation migration in context of global climate change. The mesophytic forest was the most w...

As a natural sediment trap, the marine sediments of the sheltered central part of the Maldives Inner Sea represent an exceptional archive for paleoenvironmental and climate changes in the equatorial Indian Ocean. To evaluate the complex interplay between high-latitude and monsoonal climate variability, related dust fluxes, and regional oceanographi...

This study examines the multi-decadal to centennial variability of benthic ecosystems, depositional environments and biogeochemical processes in the Gulf of Taranto (Italy) over the last millennium. Our study is based on sediment cores from two sites in the eastern Gulf of Taranto (Mediterranean Sea), and benthic foraminifera data of 43 surface sed...

We present paleo-water depth reconstructions for the Pefka E section deposited on the island of Rhodes (Greece) during the early Pleistocene. For these reconstructions, a transfer function (TF) using modern benthic foraminifera surface samples from the Adriatic and Western Mediterranean Seas has been developed. The TF model gives an overall predict...

Taxonomic list of species used in this study. (XLSX)

Reaction norm code (R). (R)

Additional figures and tables. Evaluation of the reaction norm test, ordination analyses, abundances of species in the samples, ecological preferences of the species, transfer function evaluation. (DOCX)

The Eastern Mediterranean Sea is a sink for terrigenous sediments from North Africa, Europe and Asia Minor. Its sediments therefore provide valuable information on the climate dynamics in the source areas and the associated transport processes. We present a high-resolution dataset of sediment core M40/4_SL71, which was collected SW of Crete and spa...

Coral mounds formed by framework-forming scleractinian cold-water corals (CWC; mainly Lophelia pertusa) are a common seabed feature along the Atlantic continental margins. While coral mound areas in the NE Atlantic reveal a climate-dependent temporal pattern of CWC occurrence and mound aggradation that is related to distinct environmental condition...

We studied the foraminiferal distribution in two naturally grown salt marshes from the southern North Sea with respect to the tidal frame, salinity, grain size and pH. The salt marshes are situated on the landward sides of the islands of Sylt (Rantum, Germany) and Fanø (Sønderho, Denmark). In both study areas, foraminifera have a vertical distribut...

We investigated the palynology of sediment cores from Site M0027 (IODP Exp. 313), 45 km off the present-day coast of New Jersey to infer palaeoenvironmental conditions during the second half of the Mid–Miocene Climatic Optimum and the transition to global cooler conditions. In sum 79 taxa were identified via light microscopy (13 gymnosperms, 63 ang...

In shelf and intertidal environments, benthic foraminiferal assemblages have been used in the past to successfully reconstruct Holocene relative sea-level changes. However, their applicability to reconstruct sea-levels in deeper habitats and over longer time-scales still needs to be investigated. Here, we present results from the application of a t...

We present a detailed multi-proxy data record to reveal the late Quaternary changes in marine sedimentation and biogeochemical processes of the upper bathyal Maldives (equatorial Indian Ocean) and how they are related to the benthic ecosystem dynamics. We investigated the sediment core SO-236-052-4 from the central part of the Inner Sea, Maldives,...

To constrain the use of, and better calibrate benthic foraminiferal carbon-isotope based proxies (δ¹³C) we analyzed live (Rose Bengal stained) benthic foraminifera from fjords, outer shelves, and the upper continental slope of SW-Svalbard. We further investigated whether the presence of widespread methane seepage altered benthic foraminiferal δ¹³C....