M Mojtahid
email: meryem.mojtahid@univ-angers.fr

R Hennekam

De Nooijer

W Boer

Le Houedec

De Lange

Evaluation and application of foraminiferal Element/Calcium ratios: assessing riverine fluxes and environmental conditions during sapropel S1 in the southeastern Mediterranean

Keywords: Sapropel S1, Levantine basin, Productivity, Oxygenation, Salinity, Stable isotopes, Mg/Ca, Ba/Ca, Mn/Ca, Na/Ca

Paleostudies often rely on foraminiferal calcite chemistry, which reflect past sea water condition through so-called proxy relationships. One way to evaluate robustness of these proxy relationships is to test them in well-studied and during well-constrained climate transitions. The southeastern (SE) Mediterranean is a perfect natural laboratory with a large range of past environmental conditions. These range from low productivity well-ventilated waters like they are at present, to poorly ventilated, high productivity conditions during sapropels. We here explore the reliability of recently developed foraminiferal-based proxies (Ba/Ca, Mn/Ca, Na/Ca) as tracers for changes in productivity, oxygenation and salinity during the most recent sapropel S1. We use laser ablation ICP-MS analyses of the planktonic G. ruber and six benthic species (B. alata, G. affinis, G. altiformis, G. orbicularis, H. boueana, U. peregrina). Our results show that planktonic Ba/Ca is a reliable tracer for Ba 2+ -enriched Nile outflow, where benthic Ba/Ca traces enhanced paleo(export) productivity relatively well. The interpretation of Mn/Ca data is less straightforward, and the low values may suggest a lower precipitation of Mn-oxides under prevailing hypoxia. The decrease in planktonic and benthic Na/Ca is coherent with excess Nile runoff lowering salinities in the <500m water column. However, when applying the existing calibrations, unrealistic salinity values are found, highlighting potential secondary controls on Na-incorporation. Benthic Ba/Ca time series analyses highlight a multicentennial variability in paleo(export) productivity, consistently with redox proxies. We conclude that benthic Ba/Ca records the close coupling between Ba cycling, export productivity, and redox conditions during S1 in the SE Mediterranean.

Introduction

Element concentrations and stable isotope ratios in the tests of foraminifera can be used to reconstruct past environments and climates (e.g. [START_REF] Lea | Trace elements in foraminiferal calcite[END_REF][START_REF] Lynch-Stieglitz | Tracers of Past Ocean Circulation[END_REF][START_REF] Katz | Traditional and emerging geochemical proxies in foraminifera[END_REF][START_REF] Lea | 8.14 -Elemental and Isotopic Proxies of Past Ocean Temperatures[END_REF].

Application of foraminiferal calcite chemistry depends on calibrations between incorporated elements/fractionated isotopes and one or more environmental parameters (e.g. [START_REF] Nehrke | A new model for biomineralization and trace-element signatures of Foraminifera tests[END_REF][START_REF] Mewes | The impact of Mg contents on Sr partitioning in benthic foraminifers[END_REF][START_REF] Langer | Sr partitioning in the benthic foraminifera Ammonia aomoriensis and Amphistegina lessonii[END_REF]. For instance, foraminiferal δ 18 O, which is one of the most widely applied proxies, depends on the temperature and the δ 18 O of the seawater, which in turn is defined as a function of both global ice volume and local salinity affected by evaporation and precipitation (e.g. [START_REF] Shackleton | Attainment of isotopic equilibrium between ocean water and the benthonic foraminifera genus Uvigerina: isotopic changes in the ocean during the last glacial[END_REF][START_REF] Rohling | Stable oxygen and carbon isotopes in foraminiferal carbonate shells[END_REF]. The use of foraminiferal trace/minor element incorporation (El/Ca) as an environmental proxy started with [START_REF] Hester | Water chemistry control of cadmium content in Recent benthic foraminifera[END_REF] showing that Cadmium (Cd) is incorporated into benthic foraminiferal tests proportionally to the Cd concentration of ambient seawater. This allowed thereby applying Cd/Ca as a proxy for deep-ocean circulation and nutrient chemistry (e.g. [START_REF] Marchitto | Deep water mass geometry in the glacial Atlantic Ocean: A review of constraints from the paleonutrient proxy Cd/Ca[END_REF][START_REF] Lynch-Stieglitz | Atlantic Meridional Overturning Circulation During the Last Glacial Maximum[END_REF].

Since then, calibrations were developed for a suite of elements using culture experiments, plankton tows, sediment traps and core-top studies (e.g. [START_REF] Boyle | Limits on benthic foraminiferal chemical analyses as precise measures of environmental properties[END_REF][START_REF] Rosenthal | Temperature control on the incorporation of magnesium, strontium, fluorine, and cadmium into benthic foraminiferal shells from Little Bahama Bank: Prospects for thermocline paleoceanography[END_REF][START_REF] Lea | Trace elements in foraminiferal calcite[END_REF][START_REF] Lea | Experimental determination of barium uptake in shells of the planktonic foraminifera Orbulina universa at 22°C[END_REF][START_REF] Elderfield | Calibrations for benthic foraminiferal Mg/Ca paleothermometry and the carbonate ion hypothesis[END_REF][START_REF] Rosenthal | Temperature calibration of Mg/Ca ratios in the intermediate water benthic foraminifer Hyalinea balthica[END_REF][START_REF] Schmittner | Calibration of the carbon isotope composition (δ13C) of benthic foraminifera[END_REF]. Ideally, these proxies are influenced by a single environmental variable, which in reality is rarely the case (e.g. Nürnberg et al., 1996;[START_REF] Elderfield | Calibrations for benthic foraminiferal Mg/Ca paleothermometry and the carbonate ion hypothesis[END_REF]. Despite the acknowledged limitations and uncertainties, the Mg/Ca ratio of foraminiferal calcite is a widely applied empirical proxy for ocean temperature (e.g. Elderfield and Ganssen, 2000;[START_REF] Lea | Climate Impact of Late Quaternary Equatorial Pacific Sea Surface Temperature Variations[END_REF][START_REF] Nürnberg | Paleo-sea surface temperature calculations in the equatorial east Atlantic from Mg/Ca ratios in planktic foraminifera: A comparison to sea surface temperature estimates from U37K′, oxygen isotopes, and foraminiferal transfer function[END_REF][START_REF] De Garidel-Thoron | Stable sea surface temperatures in the western Pacific warm pool over the past 1.75 million years[END_REF][START_REF] Bohaty | Foraminiferal Mg/Ca evidence for Southern Ocean cooling across the Eocene-Oligocene transition[END_REF][START_REF] Branson | The coordination of Mg in foraminiferal calcite[END_REF][START_REF] Gray | The effects of temperature, salinity, and the carbonate system on Mg/Ca in Globigerinoides ruber (white): A global sediment trap calibration[END_REF][START_REF] Gray | Nonthermal Influences on Mg/Ca in Planktonic Foraminifera: A Review of Culture Studies and Application to the Last Glacial Maximum[END_REF]. However, in addition to species-specific differences that can be overcome by robust calibration studies (e.g. Nürnberg et al., 1996;Anand et al., 2003;[START_REF] Elderfield | Calibrations for benthic foraminiferal Mg/Ca paleothermometry and the carbonate ion hypothesis[END_REF], evidence suggests that foraminiferal Mg incorporation is affected by other environmental parameters such as salinity (e.g. [START_REF] Lea | Controls on magnesium and strontium uptake in planktonic foraminifera determined by live culturing[END_REF][START_REF] Dueñas-Bohórquez | Interindividual variability and ontogenetic effects on Mg and Sr incorporation in the planktonic foraminifer Globigerinoides sacculifer[END_REF][START_REF] Honisch | The influence of salinity on Mg/Ca in planktic foraminifers -evidence from cultures, core-top sediments and complementary δ18O[END_REF], carbonate ion concentration (e.g. [START_REF] Elderfield | Calibrations for benthic foraminiferal Mg/Ca paleothermometry and the carbonate ion hypothesis[END_REF][START_REF] Rosenthal | Temperature and carbonate ion effects on Mg/Ca and Sr/Ca ratios in benthic foraminifera: Aragonitic species Hoeglundina elegans[END_REF] and Mg/Ca of the seawater (e.g. [START_REF] Segev | Effect of Mg/Ca ratio in seawater on shell composition in shallow benthic foraminifera[END_REF]. More recently Ba/Ca, Mn/Ca, and Na/Ca ratios in foraminiferal calcite were proposed as proxies for productivity, oxygenation and salinity, respectively: Incorporation of Barium in foraminiferal calcite is proportional to seawater Ba concentrations (e.g. Lea andBoyle, 1989, 1990;[START_REF] Lea | Experimental determination of barium uptake in shells of the planktonic foraminifera Orbulina universa at 22°C[END_REF][START_REF] De Nooijer | Ba incorporation in benthic foraminifera[END_REF]. In surface waters adjacent to the continent, seawater [Ba 2+ ] can reflect salinity due to the relatively high Ba/Ca of rivers or meltwater input (Guay andKenison Falkner, 1997, 1998) and thus Ba/Ca in planktonic foraminifera can be used to reconstruct past salinities in these environments (e.g. [START_REF] Weldeab | Centennial scale climate instabilities in a wet early Holocene West African monsoon[END_REF][START_REF] Weldeab | The pace of East African monsoon evolution during the Holocene[END_REF][START_REF] Bahr | Comparison of Ba/Ca and δOWATER18 as freshwater proxies: A multi-species core-top study on planktonic foraminifera from the vicinity of the Orinoco River mouth[END_REF]. Because biogenic barite (BaSO4) forms as microcrystals in decaying organic debris, BaSO4 burial fluxes are strongly linked to surface marine productivity (e.g. [START_REF] Dymond | Barium in Deep-Sea Sediment: A Geochemical Proxy for Paleoproductivity[END_REF][START_REF] Dymond | Particulate barium fluxes and their relationships to biological productivity[END_REF][START_REF] Paytan | The Role of Marine Organic Carbon and Calcite Fluxes in Driving Global Climate Change[END_REF][START_REF] Liguori | Barium and its Importance as an Indicator of (Paleo)Productivity[END_REF]. After burial at the seafloor, BaSO4 partially dissolves in undersaturated bottom waters and as such, Ba/Ca in benthic foraminifera can be used as a proxy for bottom-water Ba concentrations and implicitly, paleoproductivity (e.g. Ní Fhlaithearta et al., 2010).

Manganese is a redox-sensitive element, mainly present as Mn 2+ in sea water but precipitating as Mn oxyhydroxides under oxygenated conditions. Under low-oxygen conditions in the sediment and/or in bottom waters, Mn oxyhydroxides are reduced and Mn 2+ is released (see review in [START_REF] Lea | Trace elements in foraminiferal calcite[END_REF]. Thus, ideally, when benthic foraminifera precipitate in these conditions, more Mn will be incorporated into their calcite tests and high Mn/Ca may therefore be used as a proxy for low-oxygen conditions (e.g. [START_REF] Reichart | Single foraminiferal test chemistry records the marine environment[END_REF][START_REF] Ní Fhlaithearta | Reconstructing the seafloor environment during sapropel formation using benthic foraminiferal trace metals, stable isotopes, and sediment composition[END_REF][START_REF] Groeneveld | Mg/Ca and Mn/Ca ratios in benthic foraminifera: the potential to reconstruct past variations in temperature and hypoxia in shelf regions[END_REF][START_REF] Mckay | A comparison of benthic foraminiferal Mn / Ca and sedimentary Mn / Al as proxies of relative bottom-water oxygenation in the low-latitude NE Atlantic upwelling system[END_REF][START_REF] Koho | Benthic foraminiferal Mn / Ca ratios reflect microhabitat preferences[END_REF][START_REF] Barras | Experimental calibration of manganese incorporation in foraminiferal calcite[END_REF].

The link between Na content of biogenic carbonates and salinity was first proposed by [START_REF] Rucker | Salinity Response of Trace Element Concentration in Crassostrea virginica[END_REF] for the Atlantic oyster Crassostrea virginica, and confirmed later by [START_REF] Gordon | The influence of environmental factors on the sodium and manganese content of barnacle shells[END_REF] in fossil barnacle shells. More recently, several studies report a positive correlation between the Na/Ca of foraminiferal tests and Na which resulted in a newly proposed paleosalinity proxy (e.g. [START_REF] Wit | A novel salinity proxy based on Na incorporation into foraminiferal calcite[END_REF]Allen et al., 2016;[START_REF] Mezger | Salinity controls on Na incorporation in Red Sea planktonic foraminifera[END_REF][START_REF] Mezger | Taphonomic and Ontogenetic Effects on Na/Ca and Mg/Ca in Spinose Planktonic Foraminifera From the Red Sea[END_REF][START_REF] Mezger | Planktonic foraminiferal spine versus shell carbonate Na incorporation in relation to salinity[END_REF]. This correlation was explained by a relative increase in activity of free [Na + ] compared to [Ca 2+ ] activity with increasing salinity [START_REF] Wit | A novel salinity proxy based on Na incorporation into foraminiferal calcite[END_REF].

The eastern Mediterranean is a perfect natural laboratory to validate the reliability of these proxies due to the succession of sapropel deposits (e.g. De [START_REF] De Lange | Synchronous basin-wide formation and redox-controlled preservation of a Mediterranean sapropel[END_REF]. Deposition of these organic-rich layers is caused by: (i) freshwater flooding leading to stagnant bottom waters with reducing conditions, and (ii) high primary production (e.g. [START_REF] Rossignol-Strick | After the deluge: Mediterranean stagnation and sapropel formation[END_REF][START_REF] Rohling | Review and new aspects concerning the formation of eastern Mediterranean sapropels[END_REF][START_REF] Van Der Meer | Hydrogen isotopic compositions of long-chain alkenones record freshwater flooding of the Eastern Mediterranean at the onset of sapropel deposition[END_REF], both of which allow validating (novel) proxies. The driving force for these events is strongly associated to North African monsoon intensity fueling rivers such as the Nile, affecting the Mediterranean surface and deep water circulation (e.g. De [START_REF] De Lange | Synchronous basin-wide formation and redox-controlled preservation of a Mediterranean sapropel[END_REF][START_REF] Rohling | Mediterranean climate and oceanography, and the periodic development of anoxic events (sapropels)[END_REF].

The present study focuses on the most recent sapropel (S1; ~10 to 6 cal ka BP) from a marine sediment core PS009PC located in the southeastern (SE) Levantine Basin (Fig. 1). Core PS009PC was earlier studied for its inorganic geochemical sediment properties (Ti/Al, Ba/Al, V/Al), the oxygen and carbon isotope composition of the planktonic foraminifer Globigerinoides ruber and planktonic foraminiferal assemblages and size properties [START_REF] Hennekam | X-ray fluorescence core scanning of wet marine sediments: methods to improve quality and reproducibility of high-resolution paleoenvironmental records[END_REF][START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF][START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF]. In this study, we explore the potential of using single-chamber Ba/Ca, Mn/Ca, and Na/Ca, analyzed with laser ablation ICP-MS (LA-ICP-MS) in the planktonic foraminifer Globigerinoides ruber and in six species of benthic foraminifera (Bolivina alata, Globobulimina affinis, Gyroidina altiformis, Gyroidina orbicularis, Hanzawaia boueana, Uvigerina peregrina), as potential proxies for past changes in productivity, oxygenation and salinity during sapropel S1. In addition to contributing to a better constraint of the tested paleoproxies for future paleoenvironmental applications, this study presents a unique coupled planktonic-benthic foraminiferal dataset of laser-ICPMS elemental ratios performed on single species from the eastern Mediterranean and during a sapropel event.

Material and Methods

Core location and oceanographic settings

Piston core PS009PC (32°07.7'N, 34°24.4'E, 552 m water depth, 690 cm length) was recovered from the SE Levantine Sea in the Nile shore-parallel mud-belt during the PASSAP cruise with the R/V Pelagia (May-June 2000). The core was retrieved from a topographic elevation in order to avoid possible turbidite pathways and effects of downslope transport [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF] (Fig. 1a). At this location, sediments are composed mainly of smectites sourced from the Nile River [START_REF] Hamann | Modern and late Quaternary clay mineral distribution in the area of the SE Mediterranean Sea[END_REF] with a flux estimated at 120×10 6 t a -1 for the pre-Aswan modern times (Revel et al., 2010 and references therein). Nile-derived suspended fine sediments and freshwater are transported to our core location by means of the counterclockwise surface circulation of the eastern Mediterranean basin.

In terms of oceanographic setting, and as shown by the CTD cast performed in August 1999 during the cruise Smilable, the SE Levantine Sea comprises three main water masses (Fig. 1b). ( 1) The Modified Atlantic Water (MAW) is present in the surface 50 to 200 m and consists of a mixture of highly saline Levantine Surface Water and less saline Atlantic Water [START_REF] Manca | Physical and biochemical averaged vertical profiles in the Mediterranean regions: an important tool to trace the climatology of water masses and to validate incoming data from operational oceanography[END_REF]UNEP/MAP, 2012). This water mass increases in salinity with increasing evaporation to the east with a maximum of 38 -39 PSU in the Levantine basin [START_REF] Wüst | On the vertical circulation of the Mediterranean Sea[END_REF][START_REF] Kress | Temporal evolution of physical and chemical characteristics of the water column in the Easternmost Levantine basin (Eastern Mediterranean Sea) from 2002 to 2010[END_REF]. Temperatures vary from ~17°C in winter to ~28°C in summer [START_REF] Marullo | The sea surface temperature field in the Eastern Mediterranean from advanced very high resolution radiometer (AVHRR) data[END_REF]. [START_REF] Reimer | IntCal09 and Marine09 radiocarbon age calibration curves, 0-50[END_REF] The Levantine intermediate water (LIW) between 200 and 600 m water depth is characterized by temperatures of ~15.5°C and salinities of ~39.1 [START_REF] Kress | Temporal evolution of physical and chemical characteristics of the water column in the Easternmost Levantine basin (Eastern Mediterranean Sea) from 2002 to 2010[END_REF]. LIW is formed in the Rhodes gyre in winter, as a result of downwelling of the saline MAW after being cooled down by northern winds (UNEP/MAP, 2012). (3) The eastern Mediterranean Deep Water (EMDW), which fills up the deeper part of the basin, is cooler (~13.5°C) and less saline (~38.7) than the LIW [START_REF] Kress | Temporal evolution of physical and chemical characteristics of the water column in the Easternmost Levantine basin (Eastern Mediterranean Sea) from 2002 to 2010[END_REF].

Age model

For an accurate comparison between the proxies measured in core PS009PC, we use the same age model as published in [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF] and [START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF]. In short, the age model is based on eleven 210 Pb and seven 14 C data. The 14 C analyses were performed on approximately 10 Mg of planktonic foraminifer tests of different species. Accelerator Mass Spectrometry (AMS) 14 C ages were converted to calendar ages (years before present, BP) using the depositional model provided by OxCaL 4. 1.7 (Ramsey, 2009) based on the Marine09 radiocarbon calibration curve [START_REF] Reimer | IntCal09 and Marine09 radiocarbon age calibration curves, 0-50[END_REF] after applying a 21 year local reservoir correction. Following the age model, a sedimentation rate of ~12 cm/ka was recorded during sapropel S1.

Sedimentary geochemical analyses

The bulk inorganic analyses for Al, Ba, V and Mn were made by X-ray fluorescence using glass beads at the Institute of Chemistry and Biology of the Marine Environment (ICBM) in Oldenburg with a Philips PW 2400 X-ray spectrometer. For total organic carbon content (Corg), the samples were decalcified using 1 M hydrogen chloride, and were subsequently measured with a Fisons type NA 1500 NCS elemental analyzer (See [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF] for detailed methodology). All results reported here were published in [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF] except for Mn/Al.

Foraminiferal-based analyses

Stable oxygen and carbon isotopes

Approximately 20-30 specimens for the planktonic foraminifer Globigerinoides ruber (white) and ~5-10 specimens for each of the benthic foraminifera Uvigerina peregrina and Uvigerina mediterranea were manually selected from the 250-300 μm and >250 µm fractions, respectively. For G. ruber, δ 18 O and δ 13 C were performed at a 1-cm resolution (average of ~74 yr per sample; 95 samples from ~5 to 12 cal ka BP), and at a 4-cm resolution (average of ~296 yr per sample) for the benthic species provided there were enough tests for one measurement (21 samples with at least one of the two species from ~5 to 12 cal ka BP). The methodology and the results of δ 18 O and δ 13 C of G. ruber are published in [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF] and [START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF], respectively. In order to correct for the global effect of glacio-eustatic changes on the δ 18 OG. ruber record and therefore isolate local climatic effects (e.g. Nile freshwater input), we calculated the δ 18 O 'residuals' beyond 68% lower confidence limit following the method described in [START_REF] Grant | The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes[END_REF]. For the benthic δ 18 O and δ 13 C, cleaning of the foraminiferal samples before mass spectrometry analyses followed the same protocol as for G. ruber (i.e. cleaning with 10% hydrogen peroxide (H2O2) then methanol (CH3OH); [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF].

The cleaned foraminiferal tests were then crushed and mixed, and an amount of 20-60 µg was weighed before placing it into the Kiel-III carbonate preparation device. After reaction of the carbonate with H3PO4, the stable isotope values were measured with the MAT253 mass spectrometer at Utrecht University. Standard deviation of ± 0.04 ‰ for δ 13 C and ± 0.06‰ for δ 18 O obtained from 48 measurements of the NBS-19 standard. All oxygen and carbon isotope data are reported per mil (‰) relative to the Vienna PeeDee Belemnite.

Single foraminifera ICP-MS analyses

About 25 specimens of the planktonic foraminifer G. ruber were picked every 6 to 14 cm (8 samples in total) from ~11.0 to ~5.7 cal ka BP. For benthic foraminiferal analyses, six species (Bolivina alata, Globobulimina affinis, Gyroidina altiformis, Gyroidina orbicularis, Hanzawaia boueana, and Uvigerina peregrina) were selected from every 2 cm (33 samples in total) from ~10.8 to ~5.5 cal ka BP. Depending on the density of benthic foraminifera at each sampled level, an average of five specimens per species and per level were analyzed. The tests were cleaned by addition of ~10% hydrogen peroxide (H2O2) for 20 minutes to remove organic matter. The H2O2 was removed using a pipette and rinsed three times with double deionized water. Samples were subsequently rinsed with Methanol (CH3OH) for approximately 10 min. The specimens were then rinsed two more times with double deionized water and dried for at least 24 hours in an active fume hood (50°C). After each rinsing step, samples were ultrasonified. Foraminiferal Mg/Ca, Ba/Ca, Mn/Ca and Na/Ca were determined using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS), performed at the NIOZ (benthic foraminifera) and Utrecht University (planktonic foraminifera). The NIOZ setup consists of a NWR193UC (New Wave Research) LA-system equipped with a two-volume cell (TV2 and iCAP-Q quadrupole ICPMS (Thermo Fisher Scientific), while the Utrecht University setup consists of a 193-nm wavelength COMPex 102 ArF excimer LA system (Lambda Physik, Göttingen, Germany) connected to an Element 2 ICP-MS (Thermo Scientific, Bremen, Germany). Two chamber of each specimen of G. ruber were measured (F-1 and F-2) and each specimen of the six benthic species was measured three times on average in 3 to 4 different chambers' positions. Because of the complex organization of benthic tests, it is challenging to determine the exact chamber's position relatively to the final chamber (F). Therefore, we use the numbers 4 to 1 to represent the ontogenetic stages from the oldest to the youngest (Fig. S1). In total and all levels combined, 239 measurements were performed on G. ruber (on average 30 measurements for each sampled level) and 1374 measurements were performed on benthic specimens of the six species (on average 42 measurements for each sampled level). Analyzed masses included 23 Na, 137 Ba, 55 Mn, 43 Ca, 44 Ca, 25 Mg, 27 Al, and 57 Fe. All laser spots were 60-80 μm in diameter (depending on chamber size), repetition rate was set at 6Hz and laser energy density was set at 1 J.cm -2 . Time resolved signals were selected for integration, background subtracted, internally standardized to 43 Ca, and calibrated against a glass standard (NIST SRM610), using Thermo Qtegra software version 2.2.1465.44 and reference values from [START_REF] Jochum | Determination of Reference Values for NIST SRM 610-617 Glasses Following ISO Guidelines[END_REF]. The glass standard was ablated at a higher energy density (5 J cm -2 ). Using different ablation energies for glass and calcite was previously shown not to affect the analyses [START_REF] Wit | Approaches to unravel seasonality in sea surface temperatures using paired single-specimen foraminiferal δ18O and Mg/Ca analyses[END_REF].

Integration windows that separate the calcitic signal from background and detection of any contaminants at the test surface were done using Thermo Qtegra software version 2.2.1465.44. Each laser ablation measurement was screened for contamination and diagenetic surface coatings by monitoring Al, Mn, and Fe. On encountering surficial clay contamination (indicated by Al and Fe peaks) the data integration interval was adjusted to exclude the zone of Al, Mn, and Fe enrichment (if present). However, it has been shown that Mn-rich diagenetic overgrowths are not merely restricted to the test surface but are pervasive throughout the test (e.g. [START_REF] Sexton | Microstructural and geochemical perspectives on planktic foraminiferal preservation: "Glassy" versus "Frosty[END_REF][START_REF] Schneider | Diagenetic alteration of benthic foraminifera from a methane seep site on Vestnesa Ridge (NW Svalbard)[END_REF].

In that sense, the removal of Mn-rich contaminant phases may have required an additional reductive cleaning step [START_REF] Boyle | Comparison of Atlantic and Pacific paleochemical records for the last 215,000 years: changes in deep ocean circulation and chemical inventories[END_REF]. Here again, it has been suggested to preferentially dissolve Mg-rich biogenic carbonate, potentially introducing an analytical bias in Mg/Ca and possibly in other El/Ca ratios. An alternative way was recently proposed by [START_REF] Hasenfratz | Determination of the Mg/Mn ratio in foraminiferal coatings: An approach to correct Mg/Ca temperatures for Mn-rich contaminant phases[END_REF] to correct for Mg in the contaminant phase that may occur inside the tests. Indeed, by finding a nearly constant Mg/Mn ratio of ∼0.2 mol/mol in the Mn coating of several foraminiferal species from different settings, the following the equation ( 1) can be applied (ox represents the oxidative cleaning procedure):

(1) corrected = ox -( ox r coating)

After applying this correction to all our Mg/Ca ratios, the results show only a minor effect of this inner tests Mg-Mn rich overgrowths (~0.2 -3.5%) on the final Mg/Ca signature.

In order to convert Mg/Ca ratios into water temperatures, we used different calibration equations depending on the species. For G. ruber white, we used the pCO2 protocol of Gray and Evans ( 2019 peregrina.

Benthic foraminiferal counts and low oxygen indicative species

From ~5.5 to 10.9 cal ka BP, thirty-seven samples (every 2 cm) were analyzed for their benthic foraminiferal content. Samples were dried and washed over a 150 μm sieve. Benthic foraminiferal specimens were picked under a stereomicroscope, stored in separate Chapman slides (for each sample), and identified at a species level. In this study we only present the total number of counted specimens and the cumulative percentages of low oxygen indicative species (Cassidulinoides bradyi, Chilostomella oolina, Fursenkoina rotundata and Globobulimina affinis) as defined by Schmiedl et al.

(2010) from the nearby sediment core SL112 (Fig. 1a). To calculate the cumulative percentages, a statistical threshold of 10 individuals was established.

Time series analyses

In order to explore the frequencies in the temporal variability of selected parameters (Ba/Alsed, V/Alsed, PFAR, Ba/Cabenthics), we removed the dominant low-frequency 'precession' peak by applying a bandpass filter stopping wavelengths >2.6 kyr and analyzed the filtered records using REDFIT analyses.

These were performed using the PAST software package [START_REF] Hammer | PAST: Paleontological statistics software package for education and data analysis[END_REF]. Prior to these analyses, data were resampled (i.e. interpolated between data points) at continuous and even spaced time resolution (according to the average time-resolution; Ba/Al sed and V/Alsed = 39 yrs, PFAR = 175 yrs, and Ba/Ca benthics = 170 yrs). To overcome the large intraspecimen and interspecimen variability that is a common feature in all El/Ca ratios, analyses of Ba/Cabenthics were performed on the 2-pt average values of Ba/Cabenthics measurements including all species.

Results

Globigerinoides ruber (white) analyses

The averaged Mg/CaG.ruber values range from 3.49±0.15 to 5.23±0.30 mmol/mol (Fig. 2c). The Mg/CaG.ruber record starts with an overall decreasing trend until reaching minimum values at 7.5 cal ka BP, followed by an increase to reach maximum values at ~5.75 cal ka BP (Fig. 2c). The averaged Ba/CaG.ruber values range from 1.28 10 -3 ± 8.7 10 -5 to 2.89 10 -3 ±8.0 10 -5 mmol/mol (Fig. 2d). We observe overall high Ba/Ca values during S1 deposition with a rapid increase from 11.0 to 9.6 cal ka BP followed by a progressive decrease until 6.4 cal ka BP, and thereafter a further decrease until reaching minimum values at 5.75 cal ka BP (Fig. 2d). The average Mn/CaG.ruber values range from 0.059±0.005 to 0.12±0.009 mmol/mol (Fig. 2e). A rapid decrease in Mn/CaG.ruber values is recorded from a maximum at 11.0 to a minimum at 9.6 cal ka BP, followed by a gradual increase to reach 0.11±0.009 mmol/mol at 5.75 cal ka BP (Fig. 2e). The average Na/CaG.ruber values range from 5.80±0.11 to 6.44±0.09 mmol/mol (Fig. 2f). We observe an increase in Na/CaG.ruber values from ~11.0 to 10.0 cal ka BP, followed by a decrease to reach minimum values at 8.15 ka, and thereafter a general increase is recorded to reach maximum values at ~5.75 cal ka BP (Fig. 2f).

Benthic foraminiferal analyses

Results of oxygen isotopes (δ 18 O) measured on the benthic species U. peregrina and U. mediterranea show a gradual trend from heavy values of ~3.6‰ at 11.8 cal ka BP to more depleted values around 7.0 cal ka BP (δ 18 OU. peregrina = 1.9‰ and δ 18 O U. mediterranea = 2.1‰) (Fig. 3a). Thereafter, stable δ 18 O values of ~2.1 ‰ are recorded for both species (Fig. 3a). δ 13 CUvigerina spp. show overall low values during S1, with lighter absolute values for U. peregrina compared to U. mediterranea (Δδ 13 CU.

mediterranea-U. peregrina ~ 1.1 ‰) (Fig. 3b). δ 13 CU. peregrina values range from a minimum of -1.6‰ at ~7.6 cal ka BP to a maximum of -0.8‰ reached at 8.0 and 5.8 cal ka BP whereas δ 13 CU. mediterranea values range from a minimum of -0.3‰ at ~7.0 cal ka BP to a maximum of 0.3‰ at 10.5 cal ka BP. We observe a large variability in δ 13 CU. peregrina during the S1b phase (Fig. 3b). No data are available between 10.0 and 8.3 cal ka BP because of insufficient amounts of Uvigerina tests being present in this interval.

The total number of benthic foraminifera range from a minimum of 0 individuals at 9.4 cal ka BP to a maximum of 990 counted specimens (~1644 ind./cm²/ka) at 10.4 cal ka BP (Fig. 3b). Overall low values are present across the S1 deposit with two critical periods (9.6 -8.5 and at 7.7 ka cal BP)

presenting less than 30 individuals (Fig. 3c). These periods are characterized by a high percentage of low oxygen indicative species (C. bradyi, C. oolina, F. rotundata and G. affinis) (Fig. 3d). An interruption at ~8 cal ka BP is observed through an increase in abundances reaching 480 individuals (Fig. 3c), accompanied with a noticeable decrease in the percentage of low oxygen indicative species (Fig. 3d).

Considering all benthic foraminiferal species, Mg/Cabenthics values range from 2.12±0.13 to 14.81±1.12 mmol/mol, with an overall decreasing trend from 11 to 6.5 cal ka BP, followed by increasing values until 5.5 cal ka BP (Fig. 3e). Ba/Cabenthics values range from 1.96 10 -3 ± 0.11 10 -3 to 6.19 10 -3 ±1.4710 -3 mmol/mol, with overall high Ba/Ca values during S1 (Fig. 3f). Mn/Cabenthics values vary between 0.02±0.002 and 0.75±0.06 mmol/mol with generally low Mn/Cabenthics ratios during S1 (Fig. 3g).

Na/Cabenthics values range between 4.02±0.16 mmol/mol and 5.75±0.17 mmol/mol with an overall decreasing trend from ~11 to 7.5 cal ka BP, followed by increasing values until 5.5 cal ka BP (Fig. 3h). When considering the measured species separately, the record shows significant inter-species differences (Fig. 3e-h). The most systematic difference with respect to all elements (Mg, Ba, Mn, Na) is U. peregrina showing significantly lower El/Ca values compared to all other species (Fig. 3e-h; Table 1). Globobulimina affinis and B. alata show significantly higher Mg/Ca ratios that the other species with values ranging from 8.37±0.82 to 14.81±1.12 and 2.12±0.13 to 6.06± 0.36 mmol/mol, respectively (Fig. 3e). El/Ca ratios measured on G. orbicularis, G. altiformis and H. boueana show no significant differences except for Ba/CaH. boueana values being higher and with a larger scatter than for the other species (Fig. 3f), and for Mn/Ca values being very different between G. orbicularis and G. altiformis (Fig. 3f).

Discussion

Planktonic and benthic foraminiferal tests as reliable geochemical signal carriers during S1 in core PS009PC

In the SE Levantine basin, the planktonic species Globigerinoides ruber (white) is abundant throughout S1 in core PS009PC [START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF]. This tropical-subtropical symbiont-bearing species tolerates a large salinity gradient (~20-49 PSU; [START_REF] Bijma | Temperature and salinity limits for growth and survival of some planktonic foraminifers in laboratory cultures[END_REF]. As such, it proliferates during sapropels in low-saline and productive surface waters resulting from enhanced Nile River runoff (e.g. [START_REF] Rohling | Reconstructing past planktic foraminiferal habitats using stable isotope data: a case history for Mediterranean sapropel S5[END_REF][START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF][START_REF] Weldeab | The pace of East African monsoon evolution during the Holocene[END_REF][START_REF] Grimm | Late glacial initiation of Holocene eastern Mediterranean sapropel formation[END_REF][START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF]. Benthic foraminifera are nearly continuously present across S1 (Fig. 3c), a feature also found in nearby core SL112 [START_REF] Schmiedl | Climatic forcing of eastern Mediterranean deep-water formation and benthic ecosystems during the past 22 000 years[END_REF]. This implies that either intermittent ventilation or continuous hypoxia prevailed [START_REF] Casford | A dynamic concept for eastern Mediterranean circulation and oxygenation during sapropel formation[END_REF][START_REF] Schmiedl | Climatic forcing of eastern Mediterranean deep-water formation and benthic ecosystems during the past 22 000 years[END_REF]. Seafloor anoxia is unlikely due to the shallow position of the core (550 m water depth). That said, an exception can be made for the ~9.6-8.6 cal ka BP time period characterized by extremely low foraminiferal abundances (0 to 13 specimens; Fig. 3c) and the near exclusive presence of the deep infaunal species

Globobulimina affinis and Chilostomella oolina (Fig. 3d), suggesting that anoxia may have prevailed during this period, also at this depth. However, the surprising near-continuous presence of benthic faunas during S1 leads us to consider whether the ablated specimens are autochthonous or transported.

An autochthonous origin is most likely since Gyroidina orbicularis/altiformis, Hanzawaia boueana and Uvigerina peregrina were found as part of several sapropelic foraminiferal successions in the Mediterranean (e.g. [START_REF] Nolet | Benthic foraminiferal evidence for reduced deep-water circulation during sapropel deposition in the eastern Mediterranean[END_REF][START_REF] Casford | A dynamic concept for eastern Mediterranean circulation and oxygenation during sapropel formation[END_REF][START_REF] Kuhnt | Deep-sea ecosystem variability of the Aegean Sea during the past 22 kyr as revealed by Benthic Foraminifera[END_REF][START_REF] Schmiedl | Climatic forcing of eastern Mediterranean deep-water formation and benthic ecosystems during the past 22 000 years[END_REF][START_REF] Triantaphyllou | Holocene Climatic Optimum centennial-scale paleoceanography in the NE Aegean (Mediterranean Sea)[END_REF]. The water depth of 550 m is a typical depth limit in the eastern Mediterranean for most of the present species [START_REF] De Rijk | Organic flux control on bathymetric zonation of Mediterranean benthic foraminifera[END_REF], so that reworking from shallower sites would be an unlikely source. Core PS009PC was also retrieved from a topographic elevation, thus largely avoiding possible slumping pathways and other downslope transport features [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF]. However, because of the extremely low abundances at ~9.6 -8.6 cal ka BP, the autochthonous character of the ablated G. affinis and G. altiformis at this time interval can be questioned, suggesting that these specimens might be reworked from older samples or nearby settings.

Hence, this short period characterized most likely by a severe dysoxia should be interpreted with care, if only for the low numbers of measurements performed compared to the rest of the Sapropel record. (Fig. 2a) is closely linked to Nile River discharges. After correcting for the effect of glacio-eustatic sea-level changes [START_REF] Rohling | Sea-level and deep-sea-temperature variability over the past 5.3 million years[END_REF][START_REF] Grant | The timing of Mediterranean sapropel deposition relative to insolation, sea-level and African monsoon changes[END_REF], the effect of Nile freshwater inflow can be isolated (Fig. 2a). Furthermore, the enhanced Nile discharge introduced depleted δ 13 C terrestrial carbon explaining most of the depleted δ 13 CG. ruber values during S1 (Fig. 2b) [START_REF] Grimm | Late glacial initiation of Holocene eastern Mediterranean sapropel formation[END_REF][START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF]. The δ 18 O measured on Uvigerina spp. records the expected glacial-interglacial transition similar to the global benthic stack record of [START_REF] Lorraine | A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records[END_REF] and the other eastern Mediterranean records (e.g. ODP967; [START_REF] Ziegler | The precession phase of the boreal summer monsoon as viewed from the eastern Mediterranean (ODP Site 968)[END_REF]. Likewise, the overall depletion during S1 in δ 13 CUvigerina spp. (Fig. 3b) is similar to other Mediterranean benthic records implying significantly higher residence times of deep-water masses and/or higher influx of terrestrial dissolved organic carbon via enhanced river runoff (e.g. [START_REF] Kuhnt | Stable isotopic composition of Holocene benthic foraminifers from the Eastern Mediterranean Sea: Past changes in productivity and deep water oxygenation[END_REF][START_REF] Schmiedl | Climatic forcing of eastern Mediterranean deep-water formation and benthic ecosystems during the past 22 000 years[END_REF][START_REF] Grimm | Late glacial initiation of Holocene eastern Mediterranean sapropel formation[END_REF].

The ~1.1 ‰ difference between δ 13 CU. peregrina and δ 13 CU. mediterranea has been reported before and can be explained partly by the "vital effect" and the microhabitat preferences within the sediment (see review in [START_REF] Ravelo | Chapter Eighteen The Use of Oxygen and Carbon Isotopes of Foraminifera in Paleoceanography[END_REF][START_REF] Fontanier | Stable oxygen and carbon isotopes of live benthic foraminifera from the Bay of Biscay: Microhabitat impact and seasonal variability[END_REF].

In our record, sea surface temperatures (SST) vary between ~21.24±1.36 and 27.00±1.23°C (Fig. 2c).

These values are overall within the range of SST values reconstructed using alkenone unsaturation ratios in the Levantine during S1 (16.7 -21.9 °C at ODP967, [START_REF] Emeis | Temperature and salinity variations of Mediterranean Sea surface waters over the last 16,000 years from records of planktonic stable oxygen isotopes and alkenone unsaturation ratios[END_REF]22.3 -24 °C at GeoB 7702-3, Castañeda et al., 2010). However, these studies show that SST either remained stable or slightly increased, which is inconstant with the decrease we record in Mg/CaG. ruber values during S1 (Fig. 2c). For both methods, several effects are known to bias temperature reconstructions. While alkenone paleotemperature determinations suffer from seasonality and water depth biases (e.g. [START_REF] Castañeda | Millennial-scale sea surface temperature changes in the eastern Mediterranean (Nile River Delta region) over the last 27,000 years[END_REF]Tierney and Tingley, 2018), foraminiferal-based Mg/Ca SST reconstructions can be affected by diagenesis, salinity and pH amongst others (e.g. [START_REF] Gray | The effects of temperature, salinity, and the carbonate system on Mg/Ca in Globigerinoides ruber (white): A global sediment trap calibration[END_REF][START_REF] Gray | Nonthermal Influences on Mg/Ca in Planktonic Foraminifera: A Review of Culture Studies and Application to the Last Glacial Maximum[END_REF]. In our samples, the insignificant difference (~0.2 -3.5%) between the measured Mg/Ca and the corrected ratios [START_REF] Hasenfratz | Determination of the Mg/Mn ratio in foraminiferal coatings: An approach to correct Mg/Ca temperatures for Mn-rich contaminant phases[END_REF], and the lack of a statistically significant correlation between Mg/Ca and Mn/Ca ratios seem to indicate a minor diagenetic effect. However, in such environmental setting, these arguments might be insufficient to assert a complete absence of such diagenetic effect.

Based on eastern Mediterranean Sea core top sediments, several studies show that foraminiferal trace elements are diagenetically altered by post-depositionally precipitated high Mg carbonate calcites, most likely induced by oversaturation of carbonate ion concentration and high salinity (e.g. [START_REF] Ferguson | Systematic change of foraminiferal Mg/Ca ratios across a strong salinity gradient[END_REF][START_REF] Hoogakker | Mg/Ca paleothermometry in high salinity environments[END_REF][START_REF] Dueñas-Bohórquez | Effect of salinity and seawater calcite saturation state on Mg and Sr incorporation in cultured planktonic foraminifera[END_REF][START_REF] Kontakiotis | Field-based validation of a diagenetic effect on G. ruber Mg/Ca paleothermometry: Core top results from the Aegean Sea (eastern Mediterranean)[END_REF]. This is therefore consistent with an oversaturation-induced diagenesis leading to high Mg/Ca and Mn/Ca in G. ruber (Figs 2c; 2e) before and after the episode of runoff-induced (i.e. low salinity) S1 formation.

Salinity itself is also known to affect the incorporation of Mg into foraminiferal calcite (e.g. [START_REF] Dueñas-Bohórquez | Effect of salinity and seawater calcite saturation state on Mg and Sr incorporation in cultured planktonic foraminifera[END_REF][START_REF] Dissard | Impact of seawater pCO2 on calcification and Mg/Ca and Sr/Ca ratios in benthic foraminifera calcite: results from culturing experiments with Ammonia tepida[END_REF][START_REF] Wit | Approaches to unravel seasonality in sea surface temperatures using paired single-specimen foraminiferal δ18O and Mg/Ca analyses[END_REF][START_REF] Hönisch | The influence of salinity on Mg/Ca in planktic foraminifers -Evidence from cultures, core-top sediments and complementary δ18O. Geochim[END_REF]. This effect can be expected during S1, a period known for a large shift in surface salinity. When applying a sensitivity of ~3%/PSU [START_REF] Hönisch | The influence of salinity on Mg/Ca in planktic foraminifers -Evidence from cultures, core-top sediments and complementary δ18O. Geochim[END_REF][START_REF] Gray | The effects of temperature, salinity, and the carbonate system on Mg/Ca in Globigerinoides ruber (white): A global sediment trap calibration[END_REF], our Mg/CaG. ruber (3.5 -5.2 mmol/mol) results in an improbable ~16 PSU change, where literature in the area report 2 -4 PSU drop in surface salinity during S1 [START_REF] Kallel | Enhanced rainfall in the Mediterranean region during the last sapropel event[END_REF][START_REF] Emeis | Temperature and salinity variations of Mediterranean Sea surface waters over the last 16,000 years from records of planktonic stable oxygen isotopes and alkenone unsaturation ratios[END_REF]. Other factors such as the carbonate system (e.g. [START_REF] Gray | The effects of temperature, salinity, and the carbonate system on Mg/Ca in Globigerinoides ruber (white): A global sediment trap calibration[END_REF] or the [Mg 2+ ] of seawater itself can be also accounted for. For instance, it has been shown that the contribution of the Mg-rich Ethiopian basaltic sediments (i.e. Blue Nile) to the Nile delta were higher compared to present and progressively decreased from 12 to 5 ka cal BP (Fig. 5c; [START_REF] Revel | 21,000 Years of Ethiopian African monsoon variability recorded in sediments of the western Nile deep-sea fan[END_REF].

For benthic species, the Mg/Ca-derived bottom water temperatures are 17 ± 2.3 °C on average for G.

affinis [START_REF] Skinner | Millennial-scale variability of deep-water temperature and δ18Odw indicating deep-water source variations in the Northeast Atlantic, 0-34 cal[END_REF] and 17 ± 2.6 °C for U. peregrina when using the exponential equation of [START_REF] Lea | Experimental determination of barium uptake in shells of the planktonic foraminifera Orbulina universa at 22°C[END_REF] (Fig. 3e). These temperatures reconstructions are reasonable when compared to the present value of ~15°C at 550 m depth (Fig. 1b). However, note that most of the other calibrations available for Uvigerina genus (see review in [START_REF] Elderfield | A record of bottom water temperature and seawater δ18O for the Southern Ocean over the past 440kyr based on Mg/Ca of benthic foraminiferal Uvigerina spp[END_REF] give unrealistically warm BWT's when applied to our data, highlighting perhaps significant inter and intra-species differences within the genus [START_REF] Elderfield | A record of bottom water temperature and seawater δ18O for the Southern Ocean over the past 440kyr based on Mg/Ca of benthic foraminiferal Uvigerina spp[END_REF]. Furthermore, there appears to be an overall drop in benthic Mg/Ca during S1 (Fig. 3e) that resembles that of bottom water salinities modeled by [START_REF] Rohling | Review and new aspects concerning the formation of eastern Mediterranean sapropels[END_REF] (Fig. 6e).

Here again, several possible sources of biases, amongst which the salinity effect, are probably hampering the use of Mg/Ca as a precise paleo-thermometer in our study area and time-period.

Sapropel characteristics as derived from foraminiferal Ba/Ca ratios

The general trend of Ba/CaG. ruber is consistent with the results of [START_REF] Weldeab | The pace of East African monsoon evolution during the Holocene[END_REF] from the nearby core SL112, although with slightly higher absolute values in our study (Fig. 4a-b). This difference might be due to the use of two different forms of G. ruber, the white form in our study and the pink form in the study of [START_REF] Weldeab | The pace of East African monsoon evolution during the Holocene[END_REF]. These authors argue that the enhanced input of Ba 2+enriched Nile freshwaters during S1 served as an additional local source of Ba 2+ to the Levantine (e.g. [START_REF] Bahr | Comparison of Ba/Ca and δOWATER18 as freshwater proxies: A multi-species core-top study on planktonic foraminifera from the vicinity of the Orinoco River mouth[END_REF][START_REF] Weldeab | The pace of East African monsoon evolution during the Holocene[END_REF]. In our samples, the close link between Ba/CaG. ruber and Nile River discharges is corroborated by the comparable trend of δ 18 OG. ruber 'residuals' tracing Nile freshwater input (Fig. 4b). Hence, we interpret the variation of Ba/CaG. ruber to primarily reflect changes in Nile River discharge and so humidity changes over the Nile basin [START_REF] Weldeab | The pace of East African monsoon evolution during the Holocene[END_REF].

Benthic foraminiferal Ba/Ca ratios plot within the normal observed ranges of "small" benthic foraminiferal (i.e. opposed to tropical "large" benthic foraminifera) shell abundances (e.g. [START_REF] Lea | Trace elements in foraminiferal calcite[END_REF] 0.0015-0.005 mmol/mol) (Fig. 4e). The overall high Ba/Cabenthics values during S1 are simultaneous to high values of known paleo(export) productivity proxies from the same PS009PC core (i.e. Ba/Alsed, organic carbon content-Corg, planktonic foraminiferal accumulation rates-PFAR; Fig. 4) (e.g. [START_REF] Thomson | Review of recent advances in the interpretation of eastern Mediterranean sapropel S1 from geochemical evidence[END_REF][START_REF] Mercone | Duration of S1, the most recent sapropel in the eastern Mediterranean Sea, as indicated by accelerator mass spectrometry radiocarbon and geochemical evidence[END_REF][START_REF] De Lange | Synchronous basin-wide formation and redox-controlled preservation of a Mediterranean sapropel[END_REF][START_REF] Jilbert | Short-time-scale variability in ventilation and export productivity during the formation of Mediterranean sapropel S1[END_REF][START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF][START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF]. Therefore, the observed simultaneous increase in sedimentary Ba and incorporated Ba in benthic foraminiferal tests indicates a close coupling between Ba/Cabenthics and export productivity during S1 in the SE Levantine Basin. The same conclusions are drawn by Ní Fhlaithearta et al. ( 2010) from Ba/Ca ratios measured on Hoeglundina elegans in core SLA-9 from the Aegean Sea (Fig. 4f). However, many additional factors may affect the Ba integrated in benthic foraminiferal calcite and hence explain part of the variability reported here. For instance, the decrease in surface salinities during S1 may have decreased slightly BaSO4 precipitation (~8% at most for a salinity decrease of 2-4 units;[START_REF] Ní Fhlaithearta | Reconstructing the seafloor environment during sapropel formation using benthic foraminiferal trace metals, stable isotopes, and sediment composition[END_REF] by reducing complexation and increasing the release of free Ba 2+ (e.g. [START_REF] Millero | Use of the ion pairing model to estimate activity coefficients of the ionic components of natural waters[END_REF]. However, this effect was probably limited because Ba/Cabenthics and Ba/Alsed were ~2-3 times higher during S1 relative to the background values (Fig. 4). Alternatively, enhanced Ba/Cabenthics could be related to reduced bottom water ventilation, leading to increased residence time of deeper water Ba 2+ (Ní Fhlaithearta et al., 2010). We also note important inter-species differences (Fig. 4e) which are nonetheless common for all El/Ca ratios among benthic foraminifera and are probably the result of a combination of several effects which are not yet well constrained (e.g. calcification rate and ontogenetic effects, different biomineralization mechanisms, diagenesis and dissolution effects, microhabitat effect, etc) (e.g. Hintz et al., 2006 and references therein;[START_REF] De Nooijer | Ba incorporation in benthic foraminifera[END_REF]. In our samples, U. peregrina and H. boueana systematically yield respectively lower and higher Ba/Ca values that the other species (Fig. 4e). et al. (1995) excluded pore water effects for Ba/Ca ratios and proposed long time scale calcite recrystallization and/or dissolution effect as possibly substantially lowering Ba/Ca ratio for some species.

McCorkle

Sapropel characteristics as derived from foraminiferal Mn/Ca ratios

The overall high values of Mn/CaG. ruber ratios (0.05-0.12 mmol/mol; Fig. 5a) are unexpected as dissolved Mn is very low in surface waters (few nmol/L; e.g. [START_REF] Statham | Dissolved manganese in the North Atlantic Ocean, 0-35[END_REF]. Mn/Ca in living and recent planktonic foraminifera are typically well below 0.05 mmol/mol (e.g. [START_REF] Boyle | Manganese carbonate overgrowths on foraminifera tests[END_REF][START_REF] Russell | Uranium in foraminiferal calcite as a recorder of seawater uranium concentrations[END_REF][START_REF] Eggins | Mg/Ca variation in planktonic foraminifera tests: implications for reconstructing palaeo-seawater temperature and habitat migration[END_REF][START_REF] Barker | A study of cleaning procedures used for foraminiferal Mg/Ca paleothermometry[END_REF]. This suggests that in our case, either (i) surface waters were enriched in Mn and/or (ii) most of the Mn is of post-depositional origin. (i)

During the African Humid Period (~11.0 -8 cal ka BP; [START_REF] Revel | 21,000 Years of Ethiopian African monsoon variability recorded in sediments of the western Nile deep-sea fan[END_REF] and until the end of S1, Mn may have originated from both atmospheric input of Saharan dust and/or Nile River discharge or recycling from deeper anoxic/dysoxic water. These multiple sources may have enriched the Mn 2+ pool in the eastern Mediterranean surface waters compared to present. Nonetheless, within the range of the overall high Mn/CaG. ruber values, we observe a clear decrease during S1 that parallels the dynamics of Nile River discharges (Fig. 5a-b). This pattern might result from the relative decline in dust input into the Levantine during a period of greening of the Sahara (e.g. deMenocal et al., 2000), as shown by the ƐNd signature in the nearby MS27PT core sediments (Fig. 5c; [START_REF] Revel | 21,000 Years of Ethiopian African monsoon variability recorded in sediments of the western Nile deep-sea fan[END_REF]. (ii) The high values of Mn/CaG. ruber may also be indicative of the presence of diagenetic Mn oxyhydroxides inside the test (e.g. [START_REF] Boyle | Manganese carbonate overgrowths on foraminifera tests[END_REF][START_REF] Lea | Trace elements in foraminiferal calcite[END_REF][START_REF] Barker | A study of cleaning procedures used for foraminiferal Mg/Ca paleothermometry[END_REF]. As such, the lower Mn/CaG.ruber values recorded during S1 relative to before and after (Fig. 2e) may suggest a lower precipitation of Mn-oxides due to prevailing low-oxygen conditions.

In PS009PC and the nearby core SLA-9, the release of Mn 2+ into pore and bottom waters is reflected by the depleted sedimentary Mn (Mn/Al sed) during S1 (Fig. 5e-f). The major interest of measuring Mn/Ca in foraminifera is that, unlike the reactive Mn/Alsed, Mn concentration remains fixed once the foraminiferal calcite precipitated [START_REF] Koho | Combining benthic foraminiferal ecology and shell Mn/Ca to deconvolve past bottom water oxygenation and paleoproductivity[END_REF][START_REF] Mckay | A comparison of benthic foraminiferal Mn / Ca and sedimentary Mn / Al as proxies of relative bottom-water oxygenation in the low-latitude NE Atlantic upwelling system[END_REF]. Here again, Mn/Cabenthics values are higher (~0.1-0.8 mmol/mol; Fig. 5d) than the typical range of living and recent benthic foraminiferal calcite (<0.001 to 0.15 mmol/mol) (e.g. [START_REF] Boyle | Comparison of Atlantic and Pacific paleochemical records for the last 215,000 years: changes in deep ocean circulation and chemical inventories[END_REF][START_REF] Lea | Trace elements in foraminiferal calcite[END_REF][START_REF] Glock | EMP and SIMS studies on Mn/Ca and Fe/Ca systematics in benthic foraminifera from the Peruvian OMZ: a contribution to the identification of potential redox proxies and the impact of cleaning protocols[END_REF], probably for the same reasons as mentioned for G. ruber. Also, a significant positive correlation is found between Mn/Alsed and Mn/Ca measured on G. altiformis, G. orbicularis and U.

peregrina, which might indicate that during S1, less Mn-oxides precipitated on benthic foraminifera because of the low oxygen conditions. Additionally, there is a large variability in Mn/Ca values and trends recorded by our six benthic species (Fig. 5a). This can be either due to microhabitat preferences between the different species that calcify in different pore waters (e.g. [START_REF] Koho | Benthic foraminiferal Mn / Ca ratios reflect microhabitat preferences[END_REF] or to diagenetic processes resulting in heterogeneous Mn distribution between and within tests (e.g. [START_REF] Klinkhammer | Increased dissolved terrestrial input to the coastal ocean during the last deglaciation[END_REF][START_REF] Glock | EMP and SIMS studies on Mn/Ca and Fe/Ca systematics in benthic foraminifera from the Peruvian OMZ: a contribution to the identification of potential redox proxies and the impact of cleaning protocols[END_REF].

Sapropel characteristics as derived from foraminiferal Na/Ca ratios

Recent calibrations based on cultured and field-collected G. ruber show that Na incorporation into shell calcite increases with salinity (e.g. Allen et al., 2016;[START_REF] Mezger | Salinity controls on Na incorporation in Red Sea planktonic foraminifera[END_REF], albeit that these trends are lost in the sediment [START_REF] Mezger | Taphonomic and Ontogenetic Effects on Na/Ca and Mg/Ca in Spinose Planktonic Foraminifera From the Red Sea[END_REF]. In our case study, the overall decrease in Na/CaG. ruber during S1 is coherent with excess Nile River runoff decreasing the surface salinity of the Levantine basin [START_REF] Emeis | Temperature and salinity variations of Mediterranean Sea surface waters over the last 16,000 years from records of planktonic stable oxygen isotopes and alkenone unsaturation ratios[END_REF] (Figs. 6a-c). After applying the G. ruber (white) calibration equation of [START_REF] Mezger | Salinity controls on Na incorporation in Red Sea planktonic foraminifera[END_REF] (Na/Ca=0.57S-12.38), the reconstructed surface salinities in our record range from ~31.9 to 33.0 PSU (Fig. 6a). Pioneer studies suggest a decrease of up to 4.0 units from present (~39; Fig. 1b) (e.g. [START_REF] Vergnaud-Grazzini | Stable isotopic fractionation, climate change and episodic stagnation in the eastern Mediterranean during the late Quaternary[END_REF][START_REF] Cita | Paleoclimatic record of a long deep sea core from the eastern Mediterranean[END_REF][START_REF] Mangini | The formation of Eastern Mediterranean sapropels[END_REF], a result corroborated by [START_REF] Kallel | Enhanced rainfall in the Mediterranean region during the last sapropel event[END_REF] through modeling. More recently, by using residual variations of δ 18 OG. ruber after temperature and ice volume correction in a deep-sea core south of Cyprus (ODP967), [START_REF] Emeis | Temperature and salinity variations of Mediterranean Sea surface waters over the last 16,000 years from records of planktonic stable oxygen isotopes and alkenone unsaturation ratios[END_REF] report a decrease of about 2.0 units compared to modern surface salinity (Fig. 6c). Therefore, our Na/CaG. ruber -derived salinity estimates using the calibration equation of [START_REF] Mezger | Salinity controls on Na incorporation in Red Sea planktonic foraminifera[END_REF] appear to underestimate both the absolute values and the net salinity drop (1.0 vs. 2.0 to 4.0 units drop in the literature). The established large impact of carbonate preservation [START_REF] Mezger | Taphonomic and Ontogenetic Effects on Na/Ca and Mg/Ca in Spinose Planktonic Foraminifera From the Red Sea[END_REF]2019) from sapropel to non-sapropel conditions likely interferes with a straightforward interpretation. The very few studies tackling the use of Na/Ca on planktonic foraminifera as a potential salinity proxy face many constraints that currently hamper its quantification. For instance, recent studies show that Na is enriched in the spines of G. ruber and that the loss of spines during settling of foraminifera through the water column might explain some of the variability [START_REF] Mezger | Taphonomic and Ontogenetic Effects on Na/Ca and Mg/Ca in Spinose Planktonic Foraminifera From the Red Sea[END_REF][START_REF] Mezger | Planktonic foraminiferal spine versus shell carbonate Na incorporation in relation to salinity[END_REF]. In our data, we observe that minimum Na/CaG. ruber values (Fig. 6a) do not coincide with maximum Nile runoff as traced by Ba/CaG.ruber and δ 18 O residuals (Fig. 6b), but rather coincides with minimum Mg/CaG.ruber (Fig. 2c) (R 2 Na/Ca -Mg/Ca = 0.56). This suggests that other processes than salinity are involved in Na/Ca incorporation. For instance, some studies report that high-Mg bands in foraminiferal calcite coincide with elevated concentrations of organic molecules (e.g. Na, S), which were linked to the proximity of organic linings (e.g. [START_REF] Erez | The Source of Ions for Biomineralization in Foraminifera and Their Implications for Paleoceanographic Proxies[END_REF][START_REF] Geerken | Impact of salinity on element incorporation in two benthic foraminiferal species with contrasting magnesium contents[END_REF]. More recently, [START_REF] Mezger | Planktonic foraminiferal spine versus shell carbonate Na incorporation in relation to salinity[END_REF] showed that the Na values measured on the isolated linings indicate only a negligible relative contribution to the overall shell Na∕Ca.

Na/Ca measured on benthic foraminifera show overall low values during S1 (Fig. 6d) which might reflect a decrease in bottom water salinities. Because most sapropels were devoid of benthic microfossils, only very few estimates of past bottom water salinities are available for S1 at comparable water depths. By using an ocean general model to simulate the thermohaline circulation in the eastern Mediterranean during S1 deposition, [START_REF] Rohling | Review and new aspects concerning the formation of eastern Mediterranean sapropels[END_REF] and [START_REF] Myers | Modeling the paleocirculation of the Mediterranean: The Last Glacial Maximum and the Holocene with emphasis on the formation of sapropel S1[END_REF] show a reduction in salinity at 450-500 m water depth during S1 attaining ~37.4 (Fig. 6e). This confirms the potential of Na/Cabenthics proxy as a tracer of past bottom water salinities. In order to estimate quantitatively past salinities, we applied for the six benthic species the Na/Ca-salinity calibrations for the intertidal benthic species Ammonia tepida of [START_REF] Wit | A novel salinity proxy based on Na incorporation into foraminiferal calcite[END_REF] (Na/Ca=0.22S-0.75) and of [START_REF] Geerken | Impact of salinity on element incorporation in two benthic foraminiferal species with contrasting magnesium contents[END_REF] (Na ∕ Ca=0.064S+3.29). This correction results in both cases in unrealistic bottom waters salinities (~22. respectively) compared to the literature (~37.4 -41.0) (Figs. 6de). As for G. ruber, several biases may explain this result. The active precipitation of calcite by foraminifera, as living organisms, argues for significant biological or kinetic controls on trace element substitution, so that El/Ca signature is species specific and so should be the calibration equations (e.g. [START_REF] Lea | Trace elements in foraminiferal calcite[END_REF][START_REF] Toyofuku | Evaluation of Mg/Ca thermometry in foraminifera: Comparison of experimental results and measurements in nature[END_REF][START_REF] Geerken | Impact of salinity on element incorporation in two benthic foraminiferal species with contrasting magnesium contents[END_REF]. This is highlighted in our results by the differences in Na/Ca values between the six studied benthic species (Fig. 6d).

What processes during Sapropel 1 formation can be drawn from El/Ca proxies?

Despite the numerous limitations that may question at present the reliability of benthic foraminiferal Ba/Ca, Mn/Ca and Na/Ca ratios as paleo-proxies, the uniqueness of the present study's El/Cabenthicsdataset justifies the following attempt to uncover the environmental signal hidden behind these biases.

Amongst the three tested El/Ca proxies, Ba/Cabenthics appears to be the most reliable one, because the increase in Ba/Cabenthics during S1 is coherent with increased sedimentary Ba/Al and hence with the expected enhanced productivity as shown also by the PFAR values [START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF] (Fig. 7). In our core study and throughout S1, [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF] report that export productivity (Ba/Al) and bottom water redox conditions (V/Al) vary simultaneously with Nile discharge (δ 18 OG. ruber) on multicentennial time scales with a significant cyclicity in the 500-1000 yr band. This is supported by [START_REF] Casford | A dynamic concept for eastern Mediterranean circulation and oxygenation during sapropel formation[END_REF] who hypothesized, through observations of oxyphilic benthic foraminifera from the Aegean Sea and offshore Libya, the possibility of multiple interruptions (without precision on their duration and frequency) in the anoxia occurring throughout sapropels deposition.

In order to assess if such cyclicity is recorded by our foraminiferal productivity indicators, we bandpass filtered (i.e. remove the dominant precession-related sapropel wavelength) selected proxies from core PS009PC: Ba/Alsed and V/Al [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF], PFAR [START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF], and the averaged Ba/Ca benthics (Fig. 7). These filtered records show a similar variability (Fig. 7b) with the same significant frequency peaks in the ~1700-2200 yr, 800-1000 yr, and 400-600 yr bands during S1 formation (Fig. 7c). The ~1700-2200 yr peak is probably associated to the well-known 8.2 kyr-event, interrupting S1 (e.g. [START_REF] Rohling | Holocene atmosphere-ocean interactions: records from Greenland and the Aegean Sea[END_REF][START_REF] Tachikawa | Eastern Mediterranean Sea circulation inferred from the conditions of S1 sapropel deposition[END_REF]. Internal processes, such as a more pronounced Siberian high-pressure system involving winter cooling in the northern high latitudes (e.g. [START_REF] Pross | Massive perturbation in terrestrial ecosystems of the Eastern Mediterranean region associated with the 8[END_REF][START_REF] Schmiedl | Climatic forcing of eastern Mediterranean deep-water formation and benthic ecosystems during the past 22 000 years[END_REF][START_REF] Triantaphyllou | Holocene Climatic Optimum centennial-scale paleoceanography in the NE Aegean (Mediterranean Sea)[END_REF], and a southward migration of the intertropical convergence zone weakening the monsoon systems (e.g. [START_REF] Fleitmann | Holocene ITCZ and Indian monsoon dynamics recorded in stalagmites from Oman and Yemen (Socotra)[END_REF][START_REF] Triantaphyllou | Late Glacial-Holocene climate variability at the south-eastern margin of the Aegean Sea[END_REF] have been proposed to cause the 8.2 interruption during S1 formation. The ~800-1000 yr, and 400-600 yr peaks describe a multicentennial variability. [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF] show that the multicentennial variability observed in PS009PC δ 18 OG. ruber, Ba/Al and V/Al records is strongly resembling the atmospheric Δ 14 Cres variability [START_REF] Stuiver | INTCAL98 radiocarbon age calibration, 24,000-0 cal BP[END_REF] which mainly reflects changes in the strength of the solar activity [START_REF] Stuiver | Sun, ocean, climate and atmospheric 14CO2 : an evaluation of causal and spectral relationships[END_REF]. This corroborates a multicentennial time scale control of solar forcing on Nile discharges, productivity and deep-sea ventilation [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF], superimposed on the 21 ka-orbitally induced solar insolation cycle responsible for sapropel deposits [START_REF] Rossignol-Strick | After the deluge: Mediterranean stagnation and sapropel formation[END_REF][START_REF] Rohling | Review and new aspects concerning the formation of eastern Mediterranean sapropels[END_REF]. Solar forcing may act on Nile discharges through the modulation of the southwest Indian summer Monsoon [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF]. By bringing more nutrients to the Levantine Basin, river input likely influences productivity and thus oxygen consumption through organic matter decay [START_REF] De Lange | Synchronous basin-wide formation and redox-controlled preservation of a Mediterranean sapropel[END_REF]. Solar forcing on ventilation and productivity of the eastern Mediterranean during S1 has been also reported for a 3400 m-deep Ionian site, but with higher frequency (100 -300 to 300 -600 years cycles) [START_REF] Jilbert | Short-time-scale variability in ventilation and export productivity during the formation of Mediterranean sapropel S1[END_REF]. This difference may be partly attributed to the differing climate controls on the hydrology of northern and southern Mediterranean subbasins influenced by high (e.g. Siberian high) and south latitude climate (e.g. Indian summer monsoon, west African monsoon) respectively [START_REF] Rohling | Holocene atmosphere-ocean interactions: records from Greenland and the Aegean Sea[END_REF][START_REF] Jilbert | Short-time-scale variability in ventilation and export productivity during the formation of Mediterranean sapropel S1[END_REF][START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF]. All in all, these results confirm that, despite the analytical uncertainties, potential biases, imperfect quantitative calibrations and the lower sampling resolution, our foraminiferal-based proxies record fairly well the close multicentennial and millennial coupling between Ba cycling, export productivity, and redox conditions, during S1 in the SE Mediterranean.

Conclusions

This study provides a unique El/Ca-dataset measured on planktonic and benthic foraminifera from the SE Mediterranean. The study of the well-constrained sapropel S1 period allowed us to evaluate the robustness of newly developed proxies (Ba/Ca, Mn/Ca, Na/Ca). We draw the following key conclusions:

1) Ba/Ca, Mn/Ca and Na/Ca ratios in fossil planktonic and benthic foraminifera follow in many cases the expected surface and bottom water characteristics during S1 formation. Ba/CaG. ruber is a reliable tracer for Ba 2+ -enriched Nile freshwaters, whereas Ba/Cabenthics track enhanced paleo(export) productivity. The overall decrease in Na/Ca of both planktonic and benthic foraminifera during S1 is coherent with excess Nile River runoff resulting in a decrease in surface and bottom water salinities in the <500m water column of the Levantine basin. The interpretation of Mn/Ca data is less straightforward, probably because of additional sources of Mn to the Levant during S1, and inner tests Mn-rich overgrowths. Nevertheless, all Mn/Ca ratios show lower values during S1 suggesting a lower precipitation of Mn-oxides under prevailing hypoxic conditions.

2) Although the obtained El/Ca ratios revealed to be promising overall as paleoproxies, several issues arise. These issues are partly linked to their relatively recent development, so that not enough data are available. Amongst these, we show existing strong interspecies differences in all analyzed El/Ca and potential co-variations in elements (e.g. Mg/Ca and Na/Ca). Therefore, there is need for more species-specific calibrations from empirical, in-situ, core-top and culturing approaches in order to correct more precisely for the multiple potential sources of biases.

3) Times series analyses performed on Ba/Cabenthics highlight a multicentennial variability, in coherency with other paleo(export) productivity (Ba/Alsed, PFAR) and redox (V/Alsed) proxies from the same studied core. We therefore conclude that benthic foraminiferal Ba/Ca records the close coupling between Ba cycling, export productivity, and redox conditions, during S1 in the SE Mediterranean.

Acknowledgments

This study is part of a project MADHO (MediterraneAn Deltas in the Holocene) financed by the international program MISTRALS PaleoMEX. The "Région Pays de la Loire" is acknowledged for financial support to TANDEM project (PI: M. Mojtahid) involving the 18-month postdoctoral fellowship provided to Sandrine Le Houedec. NWO is acknowledged for financial support to PASSAP cruise and PASS2 and PALM projects. Data to support this article are from University of Angers (France) and University of Utrecht (The Netherlands). The data are available online as supplementary material and/or by contacting the first author (e-mail: meryem.mojtahid@univ-angers.fr).

Allen, K.A., Hönisch, B., Eggins, S.M., Haynes, L.L., Rosenthal, Y., Yu, J., 2016. Trace element proxies for surface ocean conditions: A synthesis of culture calibrations with planktic foraminifera. Geochim. Cosmochim. Acta 193, of G. ruber beyond 68% lower confidence limit. Note the conventional glacial-interglacial inversion of the axis values; b) δ 13 C of G. ruber [START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF]; (c-f) El/Ca ratios in mmol/mol. Mg/Ca ratios are corrected for Mg-Mn contamination phase (see text). Each dot represents the average El/Ca values of all measurements performed on G. ruber specimens at each sediment level. The colored areas represent the standard errors. Mg/Ca-SST values, presented a dashed blue curve in (c) with a with 1-sigma error, are calculated using the pCO2 protocol of [START_REF] Gray | Nonthermal Influences on Mg/Ca in Planktonic Foraminifera: A Review of Culture Studies and Application to the Last Glacial Maximum[END_REF]. Each dot represents the average El/Ca values of all measurements performed on all specimens of the same species at each sediment level. The colored areas represent the standard errors. BWT: Bottom water temperatures calculated using the equations of [START_REF] Lea | Experimental determination of barium uptake in shells of the planktonic foraminifera Orbulina universa at 22°C[END_REF] for U. peregrina (Mg/Ca=0.924e 0.061T ) and [START_REF] Skinner | Millennial-scale variability of deep-water temperature and δ18Odw indicating deep-water source variations in the Northeast Atlantic, 0-34 cal[END_REF] for G. affinis (Mg/Ca=2.91e 0.080T ).

Figure 4. a) Ba/CaG. ruber from core PS009PC; b) Ba/CaG. ruber from core SL112 [START_REF] Weldeab | The pace of East African monsoon evolution during the Holocene[END_REF] and δ 18 O residuals of G. ruber from core PS009PC. Note the conventional glacial-interglacial inversion of the δ 18 O axis values; c) Organic carbon content (Corg) and XRF-(Ba/Al) ratio in the sediment (Ba/Alsed) in core PS009PC [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF]; d) Planktonic foraminiferal accumulation rates (PFAR) from core PS009PC [START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF]. PP: Primary production; e) Ba/Ca ratios in mmol/mol for the six measured benthic foraminiferal species from core PS009PC.

Each dot represents the average El/Ca values of all measurements performed on all specimens of the same species at each sediment level. The colored areas represent the standard errors; f) Ba/Ca ratios in µmol/mol measured on the benthic foraminiferal species Hoeglundina elegans and XRF-(Ba/Al) ratio in the sediment (Ba/Alsed) from core SLA-9 (Ní Fhlaithearta et al., 2010). Thick red line represents 500 year Gaussian smoothing of (Ba/Ca)H. elegans data. 'residuals' measured on G. ruber from core PS009PC; c) Radiogenic 143 Nd/ 144 Nd (ƐNd) measured on the terrigenous fraction (<63 µm) after removal of the biogenic components in core MS27PT [START_REF] Revel | 21,000 Years of Ethiopian African monsoon variability recorded in sediments of the western Nile deep-sea fan[END_REF]; d) Mn/Ca ratios in mmol/mol of the six measured benthic foraminiferal species from core PS009PC. Each dot represents the average El/Ca values of all measurements performed on all specimens of the same species at each sediment level. The colored areas represent the standard errors ; e) XRF-(Mn/Al) ratio in the sediment in core PS009PC [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF]; f) Mn/Ca ratios in µmol/mol measured on the benthic foraminiferal species Hoeglundina elegans and XRF-(Mn/Al) ratios in the sediment from core SLA-9 (Ní Fhlaithearta et al., 2010). Thick red line represents 500 year Gaussian smoothing of (Ba/Ca)H. elegans data. Surface salinities calculated from δ 18 OG.ruber corrected for temperatures using the alkenone unsaturation index UK'37 [START_REF] Emeis | Temperature and salinity variations of Mediterranean Sea surface waters over the last 16,000 years from records of planktonic stable oxygen isotopes and alkenone unsaturation ratios[END_REF]. d) Na/Ca ratios in mmol/mol for the six measured benthic foraminiferal species from core PS009PC. Salinities are reconstructed using the equation of [START_REF] Wit | A novel salinity proxy based on Na incorporation into foraminiferal calcite[END_REF] (Na/Ca=0.22S-0.75). Each dot represents the average El/Ca values of all measurements performed on all specimens of the same species at each sediment level. The colored areas represent the standard errors; e) Schematic representation of changes in the salinity of S1 analogues of modern LIW (Levantine Intermediate Water) and EMDW (Eastern Mediterranean Deep Water) as constrained by salinity estimates derived from oxygen isotope studies in the Eastern Mediterranean [START_REF] Rohling | Review and new aspects concerning the formation of eastern Mediterranean sapropels[END_REF][START_REF] Myers | Modeling the paleocirculation of the Mediterranean: The Last Glacial Maximum and the Holocene with emphasis on the formation of sapropel S1[END_REF]. [START_REF] Hennekam | Solar forcing of Nile discharge and sapropel S1 formation in the early-to mid-Holocene eastern Mediterranean[END_REF], 2-pt moving average (red tick line) of Ba/Cabenthics in core PS009PC all benthic foraminiferal species included (each dot represents the average El/Ca values of all measurements performed on all specimens of the same species at each sediment level), and PFAR from core PS009PC [START_REF] Mojtahid | Thirteen thousand years of southeastern Mediterranean climate variability inferred from an integrative planktic foraminiferal-based approach[END_REF]; b) Band-pass filtered records of the same proxies described in (a). All frequencies >2.6 kyrs were removed; c)

  Elemental ratios with respect to Ca were based on the average of each ablation profile. The error bars of El/Ca ratios presented in Figs. 2-6 and Fig. S1 represent the standard errors of the means (= RSD/√ n); RSD being the relative standard deviation and n the number of measurements per sediment level and species.

  ) (R software package MgCaRB) to correct for pH and salinity effects. Salinity values (S) during sapropel 1 were derived from Emeis et al. (2000) and total alkalinity (AT) values were derived from the equation of Hassoun et al. (2019) from the eastern Levantine basin for surface waters (AT = 27.28*S + 1533.4). The Mg/Ca bottom water temperatures (T) are derived from the equation of Skinner et al. (2003) (Mg/Ca = 2.91e 0.08T ) for G. affinis and Lear et al. (2002) (Mg/Ca = 0.924e 0.061T ) for U.

4. 2 . 2 . 1 .

 221 Surface and deep water conditions during S1 derived from foraminiferal El/Ca 4.Geochemical signals assessed by the conventional foraminiferal-based proxies δ 18 O, δ 13 C and Mg/Ca The most conventional foraminiferal-based proxies (δ 18 O, δ 13 C) measured on G. ruber and Uvigerina spp. in core PS009PC show the expected patterns for surface and deep water characteristics during S1 (Figs. 2a-c; 3a-b). Hennekam et al. (2014) argued that the depleted G. ruber δ 18 O signal during S1

Figures captions Figure 1 .

 captions1 Figures captions

Figure 2 .

 2 Figure 2. G. ruber results from core PS009PC: a) δ 18 O (Hennekam et al., 2014) and δ 18 O 'residuals'

Figure 3 .

 3 Figure 3. Benthic foraminiferal results from core PS009PC: a-b) δ 18 O and δ 13 C measured on U. peregrina and U. mediterranea. Note the conventional glacial-interglacial inversion of the δ 18 O axis values; c) Absolute densities of benthic foraminifera; d) Cumulative percentages of low oxygen indicative species (C. bradyi, C. oolina, F. rotundata and G. affinis); (e-h) El/Ca ratios in mmol/mol measured for six benthic foraminiferal species (B. alata, G. affinis, G. orbicularis, G. altiformis, H. boueana, and U. peregrina). Mg/Ca ratios are corrected for Mg-Mn contamination phase (see text).

Figure 5 .

 5 Figure 5. a) Mn/Ca ratios in mmol/mol measured on G. ruber from core PS009PC; b) δ 13 C and δ 18 O

Figure 6 .

 6 Figure 6. a) Na/Ca of G. ruber from core PS009PC. Salinities are reconstructed using the equation of Mezger et al. (2016) (Na/Ca=0.57S-12.38); b) δ 18 O residuals of G. ruber from core PS009PC; c)

Figure 7 .

 7 Figure 7. a) Ba/Alsed and V/Alsed from core PS009PC (Hennekam et al., 2014), 2-pt moving average

  ://doi.org/10.1016/j.gca.2016.08.015 Anand, P., Elderfield, H., Conte, M.H., 2003. Mg/Ca and d18O measurements of planktonic foraminifera from Sargasso Sea. Suppl. Anand P Al 2003 Calibration MgCa Thermom. Planktonic

Table caption Table 1 .

 caption1 The averaged difference between El/Ca ratios in U. peregrina and the other benthic species found at the same sediment level.

REDFIT analyses of the filtered records in (b). All designated frequency peaks are above the theoretical red noise model AR [START_REF] Ramsey | Bayesian Analysis of Radiocarbon Dates[END_REF].

Supplementary material captions