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A Novel Eukaryotic Denitrification Pathway in Foraminifera

Abstract.

"Benthic foraminifera are unicellular eukaryotes inhabiting sediments of aquatic environments. Several species were shown to store and use nitrate for complete denitrification, a unique energy metabolism among eukaryotes. The population of benthic foraminifera reaches high densities in oxygen-depleted marine habitats, where they play a key role in the marine nitrogen cycle. However, the mechanisms of denitrification in foraminifera are still unknown, and the possibility of a contribution of associated bacteria is debated. Here, we present evidence for a novel eukaryotic denitrification pathway that is encoded in foraminiferal genomes. [...]"

Source: Current Biology
Authors: Christian Woehle et al.
DOI: 10.1016/j.cub.2018.06.027

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How nutrients are removed in oxygen-depleted regions of the ocean

"In the course of global climate change, scientists are observing the increase of low-oxygen areas in the ocean, also termed oxygen minimum zones (OMZs). Large-scale OMZs exist, for example, in the Pacific off the coast of South America or in the Indian Ocean. Since little to no oxygen is present in these regions - depending on the depth of the water - organisms whose metabolisms is independent of oxygen have a distinct advantage. These organisms include some representatives of the foraminifera: unicellular, shell-forming microorganisms, which have a nucleus and thus belong to the eukaryotes. Their life style involves a particular metabolic pathway termed anaerobic respiration. In the absence of oxygen, they convert nitrate present in the water into molecular nitrogen. [...]"

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New insights into Cenomanian paleoceanography and climate evolution from the Tarfaya Basin, southern Morocco

Abstract.

"A 325 m long continuous succession of uppermost Albian to lower Turonian pelagic (outer shelf) deposits was recovered from a new drill site in the central part of the Tarfaya Basin (southern Morocco). Natural gamma ray wireline logging, carbonate and organic carboncontent, bulk carbonate and organic carbon stable isotopes and X-ray fluorescence (XRF)-scanner derived elemental distribution data in combination with planktonic foraminiferal biostratigraphy indicate complete recovery of the Cenomanian Stage. [...]"

Source: Cretaceous Research
Authors: Sebastian Beil et al.
DOI: 10.1016/j.cretres.2017.11.006

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Mn∕Ca intra- and inter-test variability in the benthic foraminifer Ammonia tepida

Abstract.

"The adaptation of some benthic foraminiferal species to low-oxygen conditions provides the prospect of using the chemical composition of their tests as proxies for bottom water oxygenation. Manganese may be particularly suitable as such a geochemical proxy because this redox element is soluble in reduced form (Mn2+) and hence can be incorporated into benthic foraminiferal tests under low-oxygen conditions. [...]"

Source: Biogeosciences
Authors: Jassin Petersen et al.
DOI: 10.5194/bg-15-331-2018

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Ecophenotypic responses of benthic foraminifera to oxygen availability along an oxygen gradient in the California Borderland

Abstract.

"Spatial variation in environmental conditions can elicit predictable size and morphological responses in marine organisms through influences on physiology. Thus, spatial and temporal variation in marine organism size and shape are often used to infer paleoenvironmental conditions, such as dissolved oxygen concentrations. Benthic foraminifera commonly serve as a tool for reconstructing past ocean oxygen levels. [...]" 

Source: marine ecology
Authors: Caitlin R. Keating-Bitonti, Jonathan L. Payne
DOI: 10.1111/maec.12430

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