Sabine Schmidt

Université de Bordeaux, Pessac, France · UMR5805 EPOC

The study of manganese (Mn) and iron (Fe) cycling in early diagenetic processes in estuaries is crucial for understanding the functioning of these vital ecosystems and predicting their responses to environmental change. The present study investigates the dynamic interplay of Mn and Fe in early diagenetic processes at highly contrasted hydrosediment...

The French coast facing the Bay of Biscay (North-East Atlantic) is characterised by the presence of small macrotidal and turbid estuaries, including the Charente, which is geographically located between the two large estuaries of the Gironde and the Loire (south-west France). Multi-year, multi-site and high-frequency water quality surveys have show...

Sediment discharged from the Greenland Ice Sheet delivers nutrients to marine ecosystems around Greenland and shapes seafloor habitats. Current estimates of the total sediment flux are constrained by observations from land-terminating glaciers only. Addressing this gap, our study presents a budget derived from observations at 30 marine-margin locat...

Iron (Fe) is an essential micronutrient for diazotrophs, which are abundant in the Western Tropical South Pacific Ocean (WTSP). Their success depends on the numerous trace metals, particularly Fe, released from shallow hydrothermal vents along the Tonga Arc. This study aimed to explore the spatio‐temporal impact of hydrothermal fluids on particulat...

The French coast facing the Bay of Biscay (north-east Atlantic) is characterised by the presence of small macrotidal and turbid estuaries, including the Charente, geographically located between the two large estuaries of the Gironde and the Loire (south-west France). Multi-year, multi-site, high-frequency water quality surveys have shown that the L...

Coastal marshes offer natural solutions for adapting to and mitigating the effects of climate change and sea level rise. However, the resilience of the marsh physical system and, with it, the ecosystem services that it provides, is largely site specific. This calls for the increase in the spatial cover of coastal marsh studies in order to assess th...

We here present the preliminary results of an ongoing study performed on natural temporary ponds of the Landes de Gascogne (South-West of France). Here, about two thousand oligotrophic ponds develop on a sandy substrate within a landscape impacted by intensive crop farming and forestry. Global warming is expected to lengthen and intensify the dryin...

Since 30 years, an active consortium of researchers and territory managers strives for the preservation of about 3 000 temporary ponds within the SW of France, by nature conservation and restoration programs, scientific research and awareness improvement in collaboration with private and public stakeholders. Within the Natura 2000 network and natur...

Iron (Fe) is an essential micronutrient for phytoplankton, particularly diazotrophs, which are abundant in the Western Tropical South Pacific Ocean (WTSP). Their success depends on the numerous trace metals, particularly iron, released from shallow hydrothermal vents along the Tonga Arc. This study aimed to explore the impact of hydrothermal fluids...

Despite 20 years of control on eutrophication, episodes of summer hypoxia still occur in the Loire estuary, impacting water quality and posing a key scientific and management challenge. This work aimed to quantify the contribution of the benthic compartment to hypoxia in the Loire estuary by direct measurement of water–sediment fluxes and an in-dep...

The environmental variability of Northern Chilean Patagonia during the last millennia is evaluated using a multi-proxy analysis of sediment cores from Lake Esponja (45°S 72°W) to decipher if the sediment deposition is controlled by volcanic eruptions, landslides induced by earthquake or heavy rainfall. The lake is located in a glacio-tectonic valle...

Although not systematically considered as oxygen minimum zones, River-dominated Ocean Margins are sensitive to oxygen depletions. For example, the continental shelf off the Gironde, which flows into the Bay of Biscay, had not yet been studied from this perspective although recent simulations suggested that this area should already have experienced...

The benthic compartment of River-dominated Ocean Margins (RiOMar) is largely affected by sedimentary processes, as well as by natural and anthropogenic disturbances. Recent studies have confirmed the major importance of riverine inputs and local hydrodynamics in the spatial structuration of low- and high-energy temperate RiOMar, respectively. Diffe...

The Mediterranean Sea is generally described as an oligotrophic area where primary productivity is limited to a few coastal environments with nutrient-enriched fluvial input. However, several studies have revealed that the hydrology of the western Mediterranean has major seasonal productive patterns linked either to significant riverine input or to...

This paper explores extreme storms with marine flooding events in historical times. It focuses on the challenges associated with detecting these events with a degree of certainty in a changing environment. The paleoenvironmental changes which turned the Gulf of Pictons into the Belle Henriette lagoon have required the reconstruction of events to be...

Interactions among climate change, ozone depletion, and ultraviolet radiation affect aquatic ecosystems. Meteorological and biological monitoring is often too brief, however, to record the magnitudes of past changes in ultraviolet fluxes and their effects. This study presents an analysis of fossil pigments and environmental conditions in the oligot...

Live (Rose Bengal stained) shelf foraminiferal faunas have been studied at seven stations located along a shore-open ocean transect between 39 and 69-m depth in the West-Gironde Mud Patch (WGMP) (Bay of Biscay, NE Atlantic) to understand how complex environmental conditions (e.g., organic matter, oxygenation, sedimentary facies) control their ecolo...

Dans le contexte actuel du changement climatique, l’analyse croisée de l’évolution paléoenvironnementale et paléosociétale d’un secteur littoral vulnérable illustre différentes formes d’occupations humaines liées à leur environnement durant les derniers millénaires. Une analyse sédimentologique couplée avec des cartographies historiques permet de r...

The Antarctic coastal zone is an area of high primary productivity, particularly within coastal polynyas, where large phytoplankton blooms and drawdown of CO2 occur. Reconstruction of historical primary productivity changes and the associated driving factors could provide baseline insights on the role of these areas as sinks for atmospheric CO2, es...

Paleoclimate studies in Patagonia show a high Holocene climate variability, strongly controlled by the intensity and latitudinal position of the Southern Westerly Winds. In this study, environmental and climate variability, and in particular winter precipitation, was reconstructed over the last centuries through sedimentological and geochemical ana...

Marine microcharcoal records provide invaluable information to understand changes in biomass burning and its drivers over multiple glacial and interglacial cycles and to evaluate fire models under warmer climates than today. However, quantitative reconstructions of burnt area, fire intensity and frequency from these records need calibration studies...

We report high-resolution multiproxy analyses [lithology, μXRF and magnetic susceptibility (MS)] of two short gravity sediment cores from the crater Lake Gölcük, southwest Turkey. Our results provide a detailed hydroclimatic record for the last ~290 years. Aided with factor analysis of μXRF data and 210 Pb and 137 Cs dating, our multiproxy data sho...

Climate and human pressures can influence the evolution of estuarine sediment dynamics concurrently, but the understanding and quantification of their cause–effect relationships are still challenging due to the occurrence of complex hydro‐morpho‐sedimentary feedbacks. The Garonne Tidal River (GTR, upper Gironde Estuary, France) is a clear example o...

The MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon fluxes in the Mackenzie River estuary and the Beaufort Sea. During the campaign, an extensive suite of physical, chemical and biological variables were measured across seven shelf–basin transects (south–north)...

Paleolimnological reconstructions from the mid and high latitudes in the Southern Hemisphere are still relatively scarce. Anthropogenic impacts have evidenced trophic state changes and an increase in cyanobacterial blooms in the lacustrine system of San Pedro de la Paz in the last decades. Here, we reconstructed primary production and sedimentologi...

On the Bay of Biscay continental shelf, there are several mid-shelf mud patches including La Grande Vasière to the north, the West Gironde Mud Patch (WGMP) off the Gironde estuary and the Basque Mud Patch close to the Spanish border. In general, these deposits are several meters thick and cover coarser substrate. Questions remain about their storag...

Knowledge of the Marine Reservoir Effect (MRE) correction is fundamental in palaeoceanographic research to establish an accurate age-depth model for marine sedimentary records. However, during the last decades different MRE corrections have been applied in inconsistent ways for the same locality and same sediment cores, at Soledad Basin, Baja Calif...

To evaluate the stability and resilience1 of coastal ecosystem communities to perturbations that occurred during the Anthropocene,2 pre-industrial biodiversity baselines inferred from paleoarchives are needed.3,4 The study of ancient DNA (aDNA) from sediments (sedaDNA)5 has provided valuable information about past dynamics of microbial species6-8 a...

The spatial distributions of (1) surface sediment characteristics (D0.5, Sediment Surface Area (SSA), Particulate Organic Carbon (POC), Chlorophyll-a (Chl-a), Phaeophytin-a (Phaeo-a), Total and Enzymatically Hydrolyzable Amino Acids (THAA, EHAA), δ13C) and (2) sediment profile image (apparent Redox Potential Discontinuity (aRPD), numbers and depths...

Natural hazards such as earthquakes, volcanic activity, and heavy rainfall causing floods and debris avalanches are common phenomena in many tropical settings, including the island of Sumatra, located in the Indonesian archipelago. To enhance our understanding of the recurrence of these often destructive events, we studied the sedimentary infill of...

The past few decades have seen a marked acceleration in the amount of marine observation data derived using both in situ and remote sensing measurements. For example, high-frequency monitoring of key physical-chemical parameters has become an essential tool for assessing natural and human-induced changes in coastal waters as well as their consequen...

This work exposes the paleoenvironmental evolution of the Belle-Henriette lagoon and suggests a hypothesis about the infilling of the former Golfe des Pictons, in western France. Nowadays known as the Marais poitevin, this marsh is the second biggest wetland in France, covering nearly 100,000 ha. A transect composed of five sediment cores was colle...

The MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon Fluxes in the Mackenzie River estuary and the Beaufort Sea. During the campaign, an extensive suite of physical, chemical and biological variables was measured across seven shelf–basin transects (south-north)...

Grain size analysis and end‐member modeling of a long sediment core from Aysén Fjord (southern Chile) allows to identify over 25 seismo‐turbidites in the last 9,000 years. Considering the shaking intensities required to trigger these turbidites (V½‐VI½), the majority can be related to megathrust earthquakes. Multiple studies in south‐central Chile...

Outer shelf sedimentary records are promising for determining the recurrence intervals of tsunamis. However, compared to onshore deposits, offshore deposits are more difficult to access, and so far, studies of outer shelf tsunami deposits are scarce. Here, an example of studying these deposits is presented to infer implications for tsunami-related...

To improve knowledge of marine-terminating glaciers in western Greenland, marine sediment cores from the Ata Sund fjord system, hosting two outlet glaciers, Eqip Sermia and Kangilerngata Sermia, were investigated. The main objective was to reconstruct glacial activity and paleoceanographic conditions during the past 600 years. Ice-rafted debris (IR...

Environmental contextTrace elements in coastal environments represent an environmental concern and their monitoring in sediment cores provides insight into their historical sources. A well-dated core from Kiel Bay, western Baltic Sea, provided trace element data, including lead, cadmium, rare earth elements, mercury and methyl mercury. Lead and mer...

The NW Madagascar continental margin receives high loads of terrigenous particulate organic matter during the wet season and especially linked to extreme events, originating from two major rivers, the Betsiboka and the Mahavavy Rivers. This particulate matter contains a high content of iron minerals from the weathering of red ferruginous/ferralitic...

Abstract. The Antarctic coastal zone is an area of high primary productivity, particularly within coastal polynyas where large phytoplankton blooms and drawdown of CO₂ occur. Reconstruction of historical primary productivity changes, and the associated driving factors, could provide baseline insights on the role of these areas as sinks f...

The biological processes involved in the preservation, viability, and revival of long‐term dormant dinoflagellate cysts buried in sediments remain unknown. Based on studies of plant seed physiology, we tested whether the revival of ancient cysts preserved in century‐old sediments from the Bay of Brest (France) could be stimulated by melatonin and g...

The Capbreton submarine canyon is a striking feature of the south-east of the Bay of Biscay. This canyon forms a deep incision through the continental shelf and slope, and displays remarkable structures linked to its present-day hydrosedimentary activity. Its head has been disconnected from the Adour River since 1310 AD, but remains close enough to...

The Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiq...

Aysén Fjord is located in southern Chile, about 200 kilometers east of the Peru-Chile subduction trench, one of the tectonically most active regions in the world. More specifically, it is located along the southern section of this subduction zone (Valdivia segment) that hosted the largest ever instrumentally recorded earthquake. The latter is known...

Coastal-water hypoxia is increasing globally due to global warming and urbanization, and the need to define management solutions to improve the water quality of coastal ecosystems has become important. The lower tidal Garonne River (TGR; southwestern France), characterized by the seasonal presence of a turbidity maximum zone (TMZ) and urban water d...

The Green Edge initiative was developed to investigate the processes controlling the primary productivity and the fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Q...

Abstract New information on palaeoenvironmental conditions over the past ~2700 years in the Central Mediterranean Sea have been acquired through the high-resolution study of calcareous nannofossils preserved in the sediment core SW104-ND14Q recovered in the Southern Adriatic Sea (SAS) at 1013-m water depth. The surface water properties at this open...

The mass loss from the Greenland Ice Sheet has increased over the past 2 decades. Marine-terminating glaciers contribute significantly to this mass loss due to increased melting and ice discharge. Periods of rapid retreat of these tidewater glaciers have been linked to the concurrent inflow of warm Atlantic-sourced waters. However, little is known...

The 2004 Sumatra-Andaman earthquake revealed that communities in Sumatra Indonesia), particularly the Padang area, are at risk of suffering large subduction-zone earthquakes. Besides these often high-magnitude earthquakes (Mw>8), the area inland of Padang is regularly affected by earthquakes along the Great Sumatra Fault, a strike-slip fault runnin...

Globally, there has been a decrease in dissolved oxygen in the oceans, that is more pronounced in coastal waters, resulting in more frequent hypoxia exposure for many marine animals. Managing hypoxia requires an understanding of the dynamics of dissolved oxygen (DO) where it occurs. The French coast facing the Bay of Biscay (N-E Atlantic Ocean) hos...

Early diagenesis processes in the Bay of Biscay have been studied previously on short interface cores. In order to complete the data base and to characterize anoxic biogeochemical processes that affect Quaternary deposits, 1–3 m long gravity cores were collected at 150, 550, 1000 and 2000 m water depth on the continental slope of the south-eastern...

Records of ice‐rafted debris (IRD) in sediments are commonly used as a proxy for iceberg production and to reconstruct past changes of glacier stability. However, the interpretation of IRD is complex as multiple processes modulate its variability. This study investigates the relationship between IRD variability and glaciological change by measuring...