Paleostudies of the Indonesian Throughflow (ITF) are largely based on temperature and salinity reconstructions of its near surface component, whereas the variability of its lower thermocline flow has rarely been investigated. We present a multi-proxy record of KeywordsIndonesian Throughflow, Timor Sea, lower thermocline, Hoeglundina elegans Mg/Ca, Xray fluorescence core scanning.

We present core top Mg/Ca, Sr/Ca and  18 O measurements for Cibicidoides wuellerstorfi and Hoeglundina elegans from the Timor Sea and the Makassar Strait, which span a bottom water temperature (BWT) range from 2 to 18 °C. In both species Mg/Ca ratios are positively and significantly correlated with BWT, while  18 O measurements are significantly anti-correlated with BWT. Comparison of calcification temperatures derived from Mg/Ca ratios and  18 O measurements yield comparable results and closely match CTD-measured temperatures. We integrate our results with previously published data sets from the Atlantic, Indian and Pacific Oceans and provide temperature calibration equations over the temperature range from 2 to 12 °C for H. elegans and from 0 to 10 °C for C. wuellerstorfi. We found geographical differences in the relation of benthic Mg/Ca ratios to BWT: C. wuellerstorfi shows Mg/Ca sensitivity to BWT of 19% increase in Mg/Ca per °C for the Atlantic Ocean and of 15% per °C for the Indian and Pacific Oceans. Hoeglundina elegans shows Mg/Ca sensitivity to BWT of 16% increase in Mg/Ca per °C for the Atlantic Ocean and of 14% per °C for the Indian and Pacific Oceans. Cibicidoides wuellerstorfi Sr/Ca variability appears to be driven by carbonate ion saturation, whereas H. elegans Sr/Ca variability is closely linked to BWT in the compiled data sets from the Atlantic, Indian and Pacific Oceans. 2.1. Introduction The recognition that substitution of magnesium for calcium in both planktonic and benthic foraminiferal tests occurs as a temperature-controlled process [Savin and Douglas, 1973; Bender at al., 1975] led to the development of Mg/Ca ratios as a proxy for paleotemperature reconstructions [e.g.:

Marine mollusk shells have been extensively used to provide radiocarbon (14C)-based chronologies in paleoenvironmental and archaeological studies, however uncertainties in age measurements are introduced because secondary factors such as vital effects and diet may influence 14C incorporation into these shells. Deep burrowing and deposit feeding mollusks, in particular, may incorporate “old” carbon resulting in apparently older ages than their contemporary environment. In this study, we present paired 14C and stable isotope (δ13C and δ18O) measurements for nine species of known-age bivalves having different feeding strategies and collected in six localities around the NE Atlantic. We exclude potential “old” carbon contamination in these known-age mollusk shells, acquire a better understanding of local ecology and provide an improved context for the environmental interpretation of 14C ages. Our results indicate that, in the NE Atlantic, marine mollusk-derived 14C ages provide a reliable basis for environmental and archaeological investigation, independently of vital effects and differences in microhabitats, feeding strategies and sample location—all of which are apparent from stable isotopes.

Abstract. Fjords have been described as hotspots for carbon burial, potentially playing a key role within the carbon cycle as climate regulators over multiple timescales. Nevertheless, little is known about the long-term fate of the carbon that may become stored in fjordic sediments. One of the main reasons for this knowledge gap is that carbon arriving on the seafloor is prone to post-depositional degradation, posing a great challenge when trying to discriminate between an actual change in the carbon deposition rate and post-depositional carbon loss. In this study, we evaluate the use of modern benthic foraminifera as bio-indicators of organic carbon content in six voes (fjords) on the west coast of Shetland. Benthic foraminifera are known to be sensitive to changes in organic carbon content in the sediments, and changes in their assemblage composition therefore reflect synchronous variations in the quantity and quality of carbon reaching the seafloor. We identified four environments based on the relationship between benthic foraminiferal assemblages and organic carbon content in the sediments: (1) land-locked regions influenced by riverine and/or freshwater inputs of organic matter, namely the head of fjords with a restricted geomorphology; (2) stressed environments with a heavily stratified water column and sediments rich in organic matter of low nutritional value; (3) depositional environments with moderate organic content and mild or episodic current activity; and (4) marginal to coastal settings with low organic content, such as fjords with an unrestricted geomorphology. We conclude that foraminifera potentially provide a tool to disentangle primary organic carbon signals from post-depositional degradation and loss of organic carbon because of their environmental sensitivity and high preservation potential in the sedimentary record.

<p><strong>Abstract.</strong> Fjords have been described as hotspots for carbon burial, potentially playing a key role within the carbon cycle as climate regulators over multiple timescales. Nevertheless, little is known about the long-term fate of the carbon that may become stored in fjordic sediments. One of the main reasons for this knowledge gap is that carbon arriving on the seafloor is prone to post-depositional degradation, posing a great challenge when trying to discriminate between an actual change in carbon deposition rate and post depositional carbon loss. In this study, we evaluate the use of modern benthic foraminifera as bio-indicators of carbon content in six voes (fjords) on the west coast of Shetland. Benthic foraminifera are sensitive to changes in carbon content in the sediments, and changes in their assemblage composition therefore reflect synchronous variations in the quantity and quality of carbon reaching the seafloor. We identified four environments based on the relationship between benthic foraminiferal assemblages and carbon content in the sediments: 1) Land-locked regions influenced by riverine/freshwater inputs of organic matter, namely the head of fjords with a restricted geomorphology; 2) Stressed environments with a heavily stratified water column and sediments rich in organic matter of low nutritional value; 3) Depositional environments with moderate organic content and mild or episodic current activity; 4) Marginal to coastal settings with low organic content, such as fjords with an unrestricted geomorphology. We conclude that foraminifera potentially provide a tool to disentangle primary carbon signals from post-depositional degradation and loss of carbon because of their environmental sensitivity and high preservation potential in the sedimentary record.</p>

No abstract

This study attempts to reveal benthic foraminiferal responses to organic carbon in fjords system. Previous studies have revealed that benthic foraminifera are useful proxies for various environmental factors, such as oxygen content and food supply in many field. Each voe may have each sediment system because their bottom topography, surrounding environment, and river and current systems are different. These differences control the distributions of grain size, organic carbon, and benthic foraminifera. However, detailed environmental factors of each voe are not described in the manuscript.

Review of the ms "Organic carbon rich sediments: benthic foraminifera as bioindicators of depositional environments" by Elena Lo Giudice Cappelli et al. The review is based on the version of the manuscript received in April 2019. The aim of the present study is "To investigate the relationships between sedimentary OC in six west Shetland voes and the associated changes in benthic foraminiferal assemblages.. ." in order ".. .to: 1) Fingerprint the source (terrestrial vs. marine) and quality (refractory vs. labile) of organic matter and the form (organic vs. inorganic) C1