Articles | Volume 19, issue 3
https://doi.org/10.5194/bg-19-585-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-19-585-2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
02 Feb 2022
Research article |
| 02 Feb 2022
| 02 Feb 2022
Distribution of coccoliths in surface sediments across the Drake Passage and calcification of Emiliania huxleyi morphotypes
Nele Manon Vollmar
CORRESPONDING AUTHOR
Department of Geosciences, University of Bremen, P.O. Box 33 04 40, 28334 Bremen, Germany
Karl-Heinz Baumann
Department of Geosciences, University of Bremen, P.O. Box 33 04 40, 28334 Bremen, Germany
Mariem Saavedra-Pellitero
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK
Iván Hernández-Almeida
Geological Institute, Department of Earth Science, ETH Zurich, Sonneggstrasse 5, 8092, Zurich, Switzerland
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In this manuscript we combine micropalaeontology and remote-sensing. We compare the calcium carbonate produced by tiny marine algae called coccolithophores to satellite-derived particulate organic carbon in the Southern Ocean. They show good agreement north of the polar front, but hugely differ south of it. We argue that those highly reflective values could be due to small opal particles and we highlight the need to improve satellite algorithms in this unexplored part of the ocean.
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Biogeosciences, 16, 3679–3702, https://doi.org/10.5194/bg-16-3679-2019, https://doi.org/10.5194/bg-16-3679-2019, 2019
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Open ocean phytoplankton include coccolithophore algae, a key element in carbon cycle regulation with important feedbacks to the climate system. We document latitudinal variability in both coccolithophore assemblage and the mass variation in one particular species, Emiliania huxleyi, for a transect across the Drake Passage (in the Southern Ocean). Coccolithophore abundance, diversity and maximum depth habitat decrease southwards, coinciding with changes in the predominant E. huxleyi morphotypes.
Yuji Kato, Iván Hernández-Almeida, and Lara F. Pérez
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In this study, we propose an age framework for an interval of 4.8–3.1 million years ago, using fossil records of marine plankton such as diatoms and radiolarians derived from a sediment core collected in the Southern Ocean. Specifically, a total of 19 bioevents (i.e., extinction/appearance events of selected age marker species) were detected, and their precise ages were calculated. The updated biostratigraphy will contribute to future paleoceanographic work in the Southern Ocean.
Heather M. Stoll, Leopoldo D. Pena, Ivan Hernandez-Almeida, José Guitián, Thomas Tanner, and Heiko Pälike
Clim. Past, 20, 25–36, https://doi.org/10.5194/cp-20-25-2024, https://doi.org/10.5194/cp-20-25-2024, 2024
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The Oligocene and early Miocene periods featured dynamic glacial cycles on Antarctica. In this paper, we use Sr isotopes in marine carbonate sediments to document a change in the location and intensity of continental weathering during short periods of very intense Antarctic glaciation. Potentially, the weathering intensity of old continental rocks on Antarctica was reduced during glaciation. We also show improved age models for correlation of Southern Ocean and North Atlantic sediments.
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EGUsphere, https://doi.org/10.5194/egusphere-2023-2801, https://doi.org/10.5194/egusphere-2023-2801, 2023
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In this manuscript we combine micropalaeontology and remote-sensing. We compare the calcium carbonate produced by tiny marine algae called coccolithophores to satellite-derived particulate organic carbon in the Southern Ocean. They show good agreement north of the polar front, but hugely differ south of it. We argue that those highly reflective values could be due to small opal particles and we highlight the need to improve satellite algorithms in this unexplored part of the ocean.
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Based on the analysis of the response of coccolithophores’ morphological attributes in a laboratory dissolution experiment and surface sediment samples from the South China Sea, we proposed that the thickness shape (ks) factor of fossil coccoliths together with the normalized ks variation, which is the ratio of the standard deviation of ks (σ) over the mean ks (σ/ks), is a robust and novel proxy to reconstruct past changes in deep ocean carbon chemistry.
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Benthic foraminifera are key components of the ocean benthos and marine sediments. Determining their geographic distribution is highly relevant for improving our understanding of the recent and past ocean benthic ecosystem and establishing adequate conservation strategies. Here, we contribute to this knowledge by generating an open-access database of previously documented quantitative data of benthic foraminifera species from surface sediments of the eastern Pacific (BENFEP).
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Biogeosciences, 20, 597–618, https://doi.org/10.5194/bg-20-597-2023, https://doi.org/10.5194/bg-20-597-2023, 2023
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We generated high-resolution records of carbonate accumulation rate from the Miocene to the Quaternary in the tropical Atlantic Ocean to characterize the variability in pelagic carbonate production during warm climates. It follows orbital cycles, responding to local changes in tropical conditions, as well as to long-term shifts in climate and ocean chemistry. These changes were sufficiently large to play a role in the carbon cycle and global climate evolution.
Jessica G. M. Crumpton-Banks, Thomas Tanner, Ivan Hernández Almeida, James W. B. Rae, and Heather Stoll
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Past ocean carbon is reconstructed using proxies, but it is unknown whether preparing ocean sediment for one proxy might damage the data given by another. We have tested whether the extraction of an organic proxy archive from sediment samples impacts the geochemistry of tiny shells also within the sediment. We find no difference in shell geochemistry between samples which come from treated and untreated sediment. This will help us to maximize scientific return from valuable sediment samples.
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The effect of environmental conditions on the degree of calcification of marine phytoplankton remains unclear. This study implements a new microscopic approach to quantify the calcification of ancient coccolithophores, using North Atlantic sediments. Results show significant differences in the thickness and shape factor of coccoliths for samples with minimum dissolution, providing the first evaluation of phytoplankton physiology adaptation to million-year-scale variable environmental conditions.
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Low-oxygen eddies in the eastern subtropical North Atlantic can form an oasis for phytoplankton growth. Here we report on particle flux dynamics at the oligotrophic Cape Verde Ocean Observatory. We observed consistent flux patterns during the passages of low-oxygen eddies. We found distinct flux peaks in late winter, clearly exceeding background fluxes. Our findings suggest that the low-oxygen eddies sequester higher organic carbon than expected for oligotrophic settings.
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Oscar E. Romero, Karl-Heinz Baumann, Karin A. F. Zonneveld, Barbara Donner, Jens Hefter, Bambaye Hamady, Vera Pospelova, and Gerhard Fischer
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Monitoring of the multiannual evolution of populations representing different trophic levels allows for obtaining insights into the impact of climate variability in marine coastal upwelling ecosystems. By using a multiyear, continuous (1,900 d) sediment trap record, we assess the dynamics and fluxes of calcareous, organic and siliceous microorganisms off Mauritania (NW Africa). The experiment allowed for the recognition of a general sequence of seasonal variations of the main populations.
Mariem Saavedra-Pellitero, Karl-Heinz Baumann, Miguel Ángel Fuertes, Hartmut Schulz, Yann Marcon, Nele Manon Vollmar, José-Abel Flores, and Frank Lamy
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Open ocean phytoplankton include coccolithophore algae, a key element in carbon cycle regulation with important feedbacks to the climate system. We document latitudinal variability in both coccolithophore assemblage and the mass variation in one particular species, Emiliania huxleyi, for a transect across the Drake Passage (in the Southern Ocean). Coccolithophore abundance, diversity and maximum depth habitat decrease southwards, coinciding with changes in the predominant E. huxleyi morphotypes.
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Our study provides insights into the factors governing the spatio-temporal variability of coccolithophores in the equatorial North Atlantic and illustrates how this supposedly oligotrophic and stable open-ocean region actually reveals significant ecological variability. We provide evidence for Saharan dust and the Amazon River acting as fertilizers for phytoplankton and highlight the the importance of the thermocline depth for coccolithophore productivity in the lower photic zone.
Gerhard Fischer, Johannes Karstensen, Oscar Romero, Karl-Heinz Baumann, Barbara Donner, Jens Hefter, Gesine Mollenhauer, Morten Iversen, Björn Fiedler, Ivanice Monteiro, and Arne Körtzinger
Biogeosciences, 13, 3203–3223, https://doi.org/10.5194/bg-13-3203-2016, https://doi.org/10.5194/bg-13-3203-2016, 2016
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Particle fluxes at the Cape Verde Ocean Observatory in the eastern tropical North Atlantic for the period December 2009 until May 2011 are discussed based on deep sediment trap time-series data collected at 1290 and 3439 m water depths. The typically open-ocean flux pattern with weak seasonality is modified by the appearance of a highly productive and low oxygen eddy in winter 2010. The eddy passage was accompanied by high biogenic and lithogenic fluxes, lasting from December 2009 to May 2010.
B. Ausín, I. Hernández-Almeida, J.-A. Flores, F.-J. Sierro, M. Grosjean, G. Francés, and B. Alonso
Clim. Past, 11, 1635–1651, https://doi.org/10.5194/cp-11-1635-2015, https://doi.org/10.5194/cp-11-1635-2015, 2015
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Coccolithophore distribution in 88 surface sediment samples in the Atlantic Ocean and western Mediterranean was mainly influenced by salinity at 10m depth. A quantitative coccolithophore-based transfer function was developed and applied to a fossil sediment core to estimate sea surface salinity (SSS). The quality of this function and the reliability of the SSS reconstruction were assessed by statistical analyses and discussed. Several centennial SSS changes are identified for the last 15.5 ka.
I. Hernández-Almeida, F.-J. Sierro, I. Cacho, and J.-A. Flores
Clim. Past, 11, 687–696, https://doi.org/10.5194/cp-11-687-2015, https://doi.org/10.5194/cp-11-687-2015, 2015
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This manuscript presents new Mg/Ca and previously published δ18O measurements of Neogloboquadrina pachyderma sinistral for MIS 31-19, from a sediment core from the subpolar North Atlantic. The mechanism proposed here involves northward subsurface transport of warm and salty subtropical waters during periods of weaker AMOC, leading to ice-sheet instability and IRD discharge. This is the first time that these rapid climate oscillations are described for the early Pleistocene.
M. T. Horigome, P. Ziveri, M. Grelaud, K.-H. Baumann, G. Marino, and P. G. Mortyn
Biogeosciences, 11, 2295–2308, https://doi.org/10.5194/bg-11-2295-2014, https://doi.org/10.5194/bg-11-2295-2014, 2014
C. Berger, K. J. S. Meier, H. Kinkel, and K.-H. Baumann
Biogeosciences, 11, 929–944, https://doi.org/10.5194/bg-11-929-2014, https://doi.org/10.5194/bg-11-929-2014, 2014
Karl-Heinz Baumann and Babette Boeckel
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Jeremy N. Bentley, Gregory T. Ventura, Clifford C. Walters, Stefan M. Sievert, and Jeffrey S. Seewald
Biogeosciences, 19, 4459–4477, https://doi.org/10.5194/bg-19-4459-2022, https://doi.org/10.5194/bg-19-4459-2022, 2022
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Biogeosciences, 19, 1195–1209, https://doi.org/10.5194/bg-19-1195-2022, https://doi.org/10.5194/bg-19-1195-2022, 2022
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Measurements on sea-dwelling shelled organisms called foraminifera retrieved from deep-sea sediment cores have been used to reconstruct sea surface temperature (SST) variation. To evaluate the method, we use a computer model to simulate millions of single foraminifera and how they become mixed in the sediment after being deposited on the seafloor. We compare the SST inferred from the single foraminifera in the sediment core to the true SST in the water, thus quantifying method uncertainties.
Thore Friesenhagen
Biogeosciences, 19, 777–805, https://doi.org/10.5194/bg-19-777-2022, https://doi.org/10.5194/bg-19-777-2022, 2022
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Size measurements of the planktonic foraminifer Globorotalia menardii and related forms are used to investigate the shell-size evolution for the last 8 million years in the eastern tropical Atlantic Ocean. Long-term changes in the shell size coincide with major climatic, palaeogeographic and palaeoceanographic changes and suggest the occurrence of a new G. menardii type in the Atlantic Ocean ca. 2 million years ago.
Catherine V. Davis, Karen Wishner, Willem Renema, and Pincelli M. Hull
Biogeosciences, 18, 977–992, https://doi.org/10.5194/bg-18-977-2021, https://doi.org/10.5194/bg-18-977-2021, 2021
Práxedes Muñoz, Lorena Rebolledo, Laurent Dezileau, Antonio Maldonado, Christoph Mayr, Paola Cárdenas, Carina B. Lange, Katherine Lalangui, Gloria Sanchez, Marco Salamanca, Karen Araya, Ignacio Jara, Gabriel Easton, and Marcel Ramos
Biogeosciences, 17, 5763–5785, https://doi.org/10.5194/bg-17-5763-2020, https://doi.org/10.5194/bg-17-5763-2020, 2020
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We analyze marine sedimentary records to study temporal changes in oxygen and productivity in marine waters of central Chile. We observed increasing oxygenation and decreasing productivity from 6000 kyr ago to the modern era that seem to respond to El Niño–Southern Oscillation activity. In the past centuries, deoxygenation and higher productivity are re-established, mainly in the northern zones of Chile and Peru. Meanwhile, in north-central Chile the deoxygenation trend is maintained.
Luka Šupraha and Jorijntje Henderiks
Biogeosciences, 17, 2955–2969, https://doi.org/10.5194/bg-17-2955-2020, https://doi.org/10.5194/bg-17-2955-2020, 2020
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The cell size, degree of calcification and growth rates of coccolithophores impact their role in the carbon cycle and may also influence their adaptation to environmental change. Combining insights from culture experiments and the fossil record, we show that the selection for smaller cells over the past 15 Myr has been a common adaptive trait among different lineages. However, heavily calcified species maintained a more stable biogeochemical output than the ancestral lineage of E. huxleyi.
Niels J. de Winter, Clemens V. Ullmann, Anne M. Sørensen, Nicolas Thibault, Steven Goderis, Stijn J. M. Van Malderen, Christophe Snoeck, Stijn Goolaerts, Frank Vanhaecke, and Philippe Claeys
Biogeosciences, 17, 2897–2922, https://doi.org/10.5194/bg-17-2897-2020, https://doi.org/10.5194/bg-17-2897-2020, 2020
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In this study, we present a detailed investigation of the chemical composition of 12 specimens of very well preserved, 78-million-year-old oyster shells from southern Sweden. The chemical data show how the oysters grew, the environment in which they lived and how old they became and also provide valuable information about which chemical measurements we can use to learn more about ancient climate and environment from such shells. In turn, this can help improve climate reconstructions and models.
Hannah M. Palmer, Tessa M. Hill, Peter D. Roopnarine, Sarah E. Myhre, Katherine R. Reyes, and Jonas T. Donnenfield
Biogeosciences, 17, 2923–2937, https://doi.org/10.5194/bg-17-2923-2020, https://doi.org/10.5194/bg-17-2923-2020, 2020
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Modern climate change is causing expansions of low-oxygen zones, with detrimental impacts to marine life. To better predict future ocean oxygen change, we study past expansions and contractions of low-oxygen zones using microfossils of seafloor organisms. We find that, along the San Diego margin, the low-oxygen zone expanded into more shallow water in the last 400 years, but the conditions within and below the low-oxygen zone did not change significantly in the last 1500 years.
Yuanyuan Hong, Moriaki Yasuhara, Hokuto Iwatani, and Briony Mamo
Biogeosciences, 16, 585–604, https://doi.org/10.5194/bg-16-585-2019, https://doi.org/10.5194/bg-16-585-2019, 2019
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This study analyzed microfaunal assemblages in surface sediments from 52 sites in Hong Kong marine waters. We selected 18 species for linear regression modeling to statistically reveal the relationship between species distribution and environmental factors. These results show environmental preferences of commonly distributed species on Asian coasts, providing a robust baseline for past environmental reconstruction of the broad Asian region using microfossils in sediment cores.
Jorge Domingo Carrillo-Briceño, Zoneibe Luz, Austin Hendy, László Kocsis, Orangel Aguilera, and Torsten Vennemann
Biogeosciences, 16, 33–56, https://doi.org/10.5194/bg-16-33-2019, https://doi.org/10.5194/bg-16-33-2019, 2019
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By combining taxonomy and geochemistry, we corroborated the described paleoenvironments from a Neogene fossiliferous deposit of South America. Shark teeth specimens were used for taxonomic identification and as proxies for geochemical analyses. With a multidisciplinary approach we refined the understanding about the paleoenvironmental setting and the paleoecological characteristics of the studied groups, in our case, for the bull shark and its incursions into brackish waters.
Anna Binczewska, Bjørg Risebrobakken, Irina Polovodova Asteman, Matthias Moros, Amandine Tisserand, Eystein Jansen, and Andrzej Witkowski
Biogeosciences, 15, 5909–5928, https://doi.org/10.5194/bg-15-5909-2018, https://doi.org/10.5194/bg-15-5909-2018, 2018
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Primary productivity is an important factor in the functioning and structuring of the coastal ecosystem. Thus, two sediment cores from the Skagerrak (North Sea) were investigated in order to obtain a comprehensive picture of primary productivity changes during the last millennium and identify associated forcing factors (e.g. anthropogenic, climate). The cores were dated and analysed for palaeoproductivity proxies and palaeothermometers.
Sami A. Jokinen, Joonas J. Virtasalo, Tom Jilbert, Jérôme Kaiser, Olaf Dellwig, Helge W. Arz, Jari Hänninen, Laura Arppe, Miia Collander, and Timo Saarinen
Biogeosciences, 15, 3975–4001, https://doi.org/10.5194/bg-15-3975-2018, https://doi.org/10.5194/bg-15-3975-2018, 2018
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Oxygen deficiency is a major environmental problem deteriorating seafloor habitats especially in the coastal ocean with large human impact. Here we apply a wide set of chemical and physical analyses to a 1500-year long sediment record and show that, although long-term climate variability has modulated seafloor oxygenation in the coastal northern Baltic Sea, the oxygen loss over the 20th century is unprecedentedly severe, emphasizing the need to reduce anthropogenic nutrient input in the future.
Saúl González-Lemos, José Guitián, Miguel-Ángel Fuertes, José-Abel Flores, and Heather M. Stoll
Biogeosciences, 15, 1079–1091, https://doi.org/10.5194/bg-15-1079-2018, https://doi.org/10.5194/bg-15-1079-2018, 2018
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Changes in atmospheric carbon dioxide affect ocean chemistry and the ability of marine organisms to manufacture shells from calcium carbonate. We describe a technique to obtain more reproducible measurements of the thickness of calcium carbonate shells made by microscopic marine algae called coccolithophores, which will allow researchers to compare how the shell thickness responds to variations in ocean chemistry in the past and present.
Ulrich Kotthoff, Jeroen Groeneveld, Jeanine L. Ash, Anne-Sophie Fanget, Nadine Quintana Krupinski, Odile Peyron, Anna Stepanova, Jonathan Warnock, Niels A. G. M. Van Helmond, Benjamin H. Passey, Ole Rønø Clausen, Ole Bennike, Elinor Andrén, Wojciech Granoszewski, Thomas Andrén, Helena L. Filipsson, Marit-Solveig Seidenkrantz, Caroline P. Slomp, and Thorsten Bauersachs
Biogeosciences, 14, 5607–5632, https://doi.org/10.5194/bg-14-5607-2017, https://doi.org/10.5194/bg-14-5607-2017, 2017
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We present reconstructions of paleotemperature, paleosalinity, and paleoecology from the Little Belt (Site M0059) over the past ~ 8000 years and evaluate the applicability of numerous proxies. Conditions were lacustrine until ~ 7400 cal yr BP. A transition to brackish–marine conditions then occurred within ~ 200 years. Salinity proxies rarely allowed quantitative estimates but revealed congruent results, while quantitative temperature reconstructions differed depending on the proxies used.
Shuichang Zhang, Xiaomei Wang, Huajian Wang, Emma U. Hammarlund, Jin Su, Yu Wang, and Donald E. Canfield
Biogeosciences, 14, 2133–2149, https://doi.org/10.5194/bg-14-2133-2017, https://doi.org/10.5194/bg-14-2133-2017, 2017
Liza M. Roger, Annette D. George, Jeremy Shaw, Robert D. Hart, Malcolm Roberts, Thomas Becker, Bradley J. McDonald, and Noreen J. Evans
Biogeosciences, 14, 1721–1737, https://doi.org/10.5194/bg-14-1721-2017, https://doi.org/10.5194/bg-14-1721-2017, 2017
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The shell compositions of bivalve species from south Western Australia are described here to better understand the factors involved in their formation. The shell composition can be used to reconstruct past environmental conditions, but certain species manifest an offset compared to the environmental parameters measured. As shown here, shells that experience the same conditions can present different compositions in relation to structure, organic composition and environmental conditions.
Johan Vellekoop, Lineke Woelders, Sanem Açikalin, Jan Smit, Bas van de Schootbrugge, Ismail Ö. Yilmaz, Henk Brinkhuis, and Robert P. Speijer
Biogeosciences, 14, 885–900, https://doi.org/10.5194/bg-14-885-2017, https://doi.org/10.5194/bg-14-885-2017, 2017
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The Cretaceous–Paleogene boundary, ~ 66 Ma, is characterized by a mass extinction. We studied groups of both surface-dwelling and bottom-dwelling organisms to unravel the oceanographic consequences of these extinctions. Our integrated records indicate that a reduction of the transport of organic matter to the sea floor resulted in enhanced recycling of nutrients in the upper water column and decreased food supply at the sea floor in the first tens of thousands of years after the extinctions.
Johan Renaudie
Biogeosciences, 13, 6003–6014, https://doi.org/10.5194/bg-13-6003-2016, https://doi.org/10.5194/bg-13-6003-2016, 2016
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Marine planktonic diatoms are today both the main silica and carbon exporter to the deep sea. However, 50 million years ago, radiolarians were the main silica exporter and diatoms were a rare, geographically restricted group. Quantification of their rise to dominance suggest that diatom abundance is primarily controlled by the continental weathering and has a negative feedback, observable on a geological timescale, on the carbon cycle.
Jelena Vidović, Rafał Nawrot, Ivo Gallmetzer, Alexandra Haselmair, Adam Tomašových, Michael Stachowitsch, Vlasta Ćosović, and Martin Zuschin
Biogeosciences, 13, 5965–5981, https://doi.org/10.5194/bg-13-5965-2016, https://doi.org/10.5194/bg-13-5965-2016, 2016
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We studied the ecological history of the Gulf of Trieste. Before the 20th century, the only activity here was ore mining, releasing high amounts of mercury into its northern part, Panzano Bay. Mercury did not cause changes to microorganisms, as it is not bioavailable. In the 20th century, agriculture caused nutrient enrichment in the bay and increased diversity of microorganisms. Industrial activities increased the concentrations of pollutants, causing only minor changes to microorganisms.
Aurélie Penaud, Frédérique Eynaud, Antje Helga Luise Voelker, and Jean-Louis Turon
Biogeosciences, 13, 5357–5377, https://doi.org/10.5194/bg-13-5357-2016, https://doi.org/10.5194/bg-13-5357-2016, 2016
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This paper presents new analyses conducted at high resolution in the Gulf of Cadiz over the last 50 ky. Palaeohydrological changes in these subtropical latitudes are discussed through dinoflagellate cyst assemblages but also dinocyst transfer function results, implying sea surface temperature and salinity as well as annual productivity reconstructions. This study is thus important for our understanding of past and future productivity regimes, also implying consequences on the biological pump.
William Hardy, Aurélie Penaud, Fabienne Marret, Germain Bayon, Tania Marsset, and Laurence Droz
Biogeosciences, 13, 4823–4841, https://doi.org/10.5194/bg-13-4823-2016, https://doi.org/10.5194/bg-13-4823-2016, 2016
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Our approach is based on a multi-proxy study from a core collected off the Congo River and discusses surface oceanic conditions (upwelling cells, river-induced upwelling), land–sea interactions and terrestrial erosion and in particular enables us to spatially constrain the migration of atmospheric systems. This paper thus presents new data highlighting, with the highest resolution ever reached in this region, the great correlation between phytoplanktonic organisms and monsoonal mechanisms.
Philippine Campagne, Xavier Crosta, Sabine Schmidt, Marie Noëlle Houssais, Olivier Ther, and Guillaume Massé
Biogeosciences, 13, 4205–4218, https://doi.org/10.5194/bg-13-4205-2016, https://doi.org/10.5194/bg-13-4205-2016, 2016
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Diatoms and biomarkers have been recently used for palaeoclimate reconstructions in the Southern Ocean. Few sediment-based ecological studies have investigated their relationships with environmental conditions. Here, we compare high-resolution sedimentary records with meteorological data to study relationships between our proxies and recent atmospheric and sea surface changes. Our results indicate that coupled wind pattern and sea surface variability act as the proximal forcing at that scale.
Niels A. G. M. van Helmond, Appy Sluijs, Nina M. Papadomanolaki, A. Guy Plint, Darren R. Gröcke, Martin A. Pearce, James S. Eldrett, João Trabucho-Alexandre, Ireneusz Walaszczyk, Bas van de Schootbrugge, and Henk Brinkhuis
Biogeosciences, 13, 2859–2872, https://doi.org/10.5194/bg-13-2859-2016, https://doi.org/10.5194/bg-13-2859-2016, 2016
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Over the past decades large changes have been observed in the biogeographical dispersion of marine life resulting from climate change. To better understand present and future trends it is important to document and fully understand the biogeographical response of marine life during episodes of environmental change in the geological past.
Here we investigate the response of phytoplankton, the base of the marine food web, to a rapid cold spell, interrupting greenhouse conditions during the Cretaceous.
Thomas C. Brachert, Markus Reuter, Stefan Krüger, Julia Kirkerowicz, and James S. Klaus
Biogeosciences, 13, 1469–1489, https://doi.org/10.5194/bg-13-1469-2016, https://doi.org/10.5194/bg-13-1469-2016, 2016
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We present stable isotope proxy data and calcification records from fossil reef corals. The corals investigated derive from the Florida carbonate platform and are of middle Pliocene to early Pleistocene age. From the data we infer an environment subject to intermittent upwelling on annual to decadal timescales. Calcification rates were enhanced during periods of upwelling. This is likely an effect of dampened SSTs during the upwelling.
B. A. A. Hoogakker, D. J. R. Thornalley, and S. Barker
Biogeosciences, 13, 211–221, https://doi.org/10.5194/bg-13-211-2016, https://doi.org/10.5194/bg-13-211-2016, 2016
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Models predict a decrease in future ocean O2, driven by surface water warming and freshening in the polar regions, causing a reduction in ocean circulation. Here we assess this effect in the past, focussing on the response of deep and intermediate waters from the North Atlantic during large-scale ice rafting and millennial-scale cooling events of the last glacial.
Our assessment agrees with the models but also highlights the importance of biological processes driving ocean O2 change.
M. Hermoso, I. Z. X. Chan, H. L. O. McClelland, A. M. C. Heureux, and R. E. M. Rickaby
Biogeosciences, 13, 301–312, https://doi.org/10.5194/bg-13-301-2016, https://doi.org/10.5194/bg-13-301-2016, 2016
B. Metcalfe, W. Feldmeijer, M. de Vringer-Picon, G.-J. A. Brummer, F. J. C. Peeters, and G. M. Ganssen
Biogeosciences, 12, 4781–4807, https://doi.org/10.5194/bg-12-4781-2015, https://doi.org/10.5194/bg-12-4781-2015, 2015
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Iron biogeochemical budgets during the natural ocean fertilisation experiment KEOPS-2 showed that complex circulation and transport pathways were responsible for differences in the mode and strength of iron supply, with vertical supply dominant on the plateau and lateral supply dominant in the plume. The exchange of iron between dissolved, biogenic and lithogenic pools was highly dynamic, resulting in a decoupling of iron supply and carbon export and controlling the efficiency of fertilisation.
J. P. D'Olivo, M. T. McCulloch, S. M. Eggins, and J. Trotter
Biogeosciences, 12, 1223–1236, https://doi.org/10.5194/bg-12-1223-2015, https://doi.org/10.5194/bg-12-1223-2015, 2015
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The boron isotope composition in the skeleton of massive Porites corals from the central Great Barrier Reef is used to reconstruct the seawater pH over the 1940-2009 period. The long-term decline in the coral-reconstructed seawater pH is in close agreement with estimates based on the CO2 uptake by surface waters due to rising atmospheric levels. We also observed a significant relationship between terrestrial runoff data and the inshore coral boron isotopes records.
J. Schönfeld, W. Kuhnt, Z. Erdem, S. Flögel, N. Glock, M. Aquit, M. Frank, and A. Holbourn
Biogeosciences, 12, 1169–1189, https://doi.org/10.5194/bg-12-1169-2015, https://doi.org/10.5194/bg-12-1169-2015, 2015
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Today’s oceans show distinct mid-depth oxygen minima while whole oceanic basins became transiently anoxic in the Mesozoic. To constrain past bottom-water oxygenation, we compared sediments from the Peruvian OMZ with the Cenomanian OAE 2 from Morocco. Corg accumulation rates in laminated OAE 2 sections match Holocene rates off Peru. Laminated deposits are found at oxygen levels of < 7µmol kg-1; crab burrows appear at 10µmol kg-1 today, both defining threshold values for palaeoreconstructions.
S. C. Löhr and M. J. Kennedy
Biogeosciences, 11, 4971–4983, https://doi.org/10.5194/bg-11-4971-2014, https://doi.org/10.5194/bg-11-4971-2014, 2014
R. Hoffmann, J. A. Schultz, R. Schellhorn, E. Rybacki, H. Keupp, S. R. Gerden, R. Lemanis, and S. Zachow
Biogeosciences, 11, 2721–2739, https://doi.org/10.5194/bg-11-2721-2014, https://doi.org/10.5194/bg-11-2721-2014, 2014
T. J. Algeo, P. A. Meyers, R. S. Robinson, H. Rowe, and G. Q. Jiang
Biogeosciences, 11, 1273–1295, https://doi.org/10.5194/bg-11-1273-2014, https://doi.org/10.5194/bg-11-1273-2014, 2014
C. Berger, K. J. S. Meier, H. Kinkel, and K.-H. Baumann
Biogeosciences, 11, 929–944, https://doi.org/10.5194/bg-11-929-2014, https://doi.org/10.5194/bg-11-929-2014, 2014
T. Caley, S. Zaragosi, J. Bourget, P. Martinez, B. Malaizé, F. Eynaud, L. Rossignol, T. Garlan, and N. Ellouz-Zimmermann
Biogeosciences, 10, 7347–7359, https://doi.org/10.5194/bg-10-7347-2013, https://doi.org/10.5194/bg-10-7347-2013, 2013
N. Preto, C. Agnini, M. Rigo, M. Sprovieri, and H. Westphal
Biogeosciences, 10, 6053–6068, https://doi.org/10.5194/bg-10-6053-2013, https://doi.org/10.5194/bg-10-6053-2013, 2013
I. Polovodova Asteman, K. Nordberg, and H. L. Filipsson
Biogeosciences, 10, 1275–1290, https://doi.org/10.5194/bg-10-1275-2013, https://doi.org/10.5194/bg-10-1275-2013, 2013
J.-E. Tesdal, E. D. Galbraith, and M. Kienast
Biogeosciences, 10, 101–118, https://doi.org/10.5194/bg-10-101-2013, https://doi.org/10.5194/bg-10-101-2013, 2013
L. Durantou, A. Rochon, D. Ledu, G. Massé, S. Schmidt, and M. Babin
Biogeosciences, 9, 5391–5406, https://doi.org/10.5194/bg-9-5391-2012, https://doi.org/10.5194/bg-9-5391-2012, 2012
C. A. Grove, J. Zinke, T. Scheufen, J. Maina, E. Epping, W. Boer, B. Randriamanantsoa, and G.-J. A. Brummer
Biogeosciences, 9, 3063–3081, https://doi.org/10.5194/bg-9-3063-2012, https://doi.org/10.5194/bg-9-3063-2012, 2012
D. Wall-Palmer, M. B. Hart, C. W. Smart, R. S. J. Sparks, A. Le Friant, G. Boudon, C. Deplus, and J. C. Komorowski
Biogeosciences, 9, 309–315, https://doi.org/10.5194/bg-9-309-2012, https://doi.org/10.5194/bg-9-309-2012, 2012
S. F. Rella and M. Uchida
Biogeosciences, 8, 3545–3553, https://doi.org/10.5194/bg-8-3545-2011, https://doi.org/10.5194/bg-8-3545-2011, 2011
M. C. Nash, U. Troitzsch, B. N. Opdyke, J. M. Trafford, B. D. Russell, and D. I. Kline
Biogeosciences, 8, 3331–3340, https://doi.org/10.5194/bg-8-3331-2011, https://doi.org/10.5194/bg-8-3331-2011, 2011
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Short summary
We studied recent (sub-)fossil remains of a type of algae (coccolithophores) off southernmost Chile and across the Drake Passage, adding to the scarce knowledge that exists in the Southern Ocean, a rapidly changing environment. We found that those can be used to reconstruct the surface ocean conditions in the north but not in the south. We also found variations in shape in the dominant species Emiliania huxleyi depending on the location, indicating subtle adaptations to environmental conditions.
We studied recent (sub-)fossil remains of a type of algae (coccolithophores) off southernmost...
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