In modern environments, pore water geochemistry and modelling simulations allow the study of methane (CH) sources and sinks at any geographic location. However, reconstructing CH dynamics in geological records is challenging. Here, we show that the benthic foraminiferal δS can be used to reconstruct the flux (i.e., diffusive vs. advective) and timing of CH emissions in fossil records. We measured the δS of Cassidulina neoteretis specimens from selected samples collected at Vestnesa Ridge, a methane cold seep site in the Arctic Ocean. Our results show lower benthic foraminiferal δS values (∼20‰) in the sample characterized by seawater conditions, whereas higher values (∼25-27‰) were measured in deeper samples as a consequence of the presence of past sulphate-methane transition zones. The correlation between δS and the bulk benthic foraminiferal δC supports this interpretation, whereas the foraminiferal δO-δS correlation indicates CH advection at the studied site during the Early Holocene and the Younger-Dryas - post-Bølling. This study highlights the potential of the benthic foraminiferal δS as a novel tool to reconstruct the flux of CH emissions in geological records and to indirectly date fossil seeps.
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http://dx.doi.org/10.1038/s41598-020-58353-4 | DOI Listing |
ISME J
December 2024
Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.
Investigations of the metabolic capabilities of anaerobic protists advances our understanding of the evolution of eukaryotic life on Earth and for uncovering analogous extraterrestrial complex microbial life. Certain species of foraminiferan protists live in environments analogous to early Earth conditions when eukaryotes evolved, including sulfidic, anoxic, and hypoxic sediment porewaters. Foraminifera are known to form symbioses as well as to harbor organelles from other eukaryotes (chloroplasts), possibly bolstering the host's independence from oxygen.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2024
Environmental Biophysics and Molecular Ecology Program, Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901.
Foraminifera are unicellular protists capable of precipitating calcite tests, which fossilize and preserve geochemical signatures of past environmental conditions dating back to the Cambrian period. The biomineralization mechanisms responsible for the mineral structures, which are key to interpreting palaeoceanographic signals, are poorly understood. Here, we present an extensive analysis of the test-bound proteins.
View Article and Find Full Text PDFPeerJ
December 2024
Ocean Sciences, NIOZ-Netherlands Institute for Sea Research, Texel, Netherlands.
Marine biogenic calcium carbonate production plays a role in the exchange of CO between ocean and atmosphere. The effect of increased CO on calcification and on the resulting chemistry of shells and skeletons, however, is only partly understood. Foraminifera are among the main marine CaCO producers and the controls on element partitioning and isotope fractionation is the subject of many recent investigations.
View Article and Find Full Text PDFSci Data
November 2024
Department of Genetics and Evolution, University of Geneva, 1211, Geneva 4, Switzerland.
Sci Total Environ
December 2024
Department of Analytical Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Poznań, Poland.
Polar ecosystems are considered very fragile, however, due to the short observation record it is hard to assess the recovery processes of the coastal and fjord environments after a major disturbance. Here, we provide a unique case study from South Georgia (sub-Antarctic), an area seriously affected by the whaling industry. The study focuses on King Edward Cove, serving as a sheltered harbor for the former whaling station at Grytviken, as well as other parts of Cumberland Bay considered to represent generally pristine areas.
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