News

When oxygen disappeared, early marine animals really started evolving

"Animals need oxygen to survive, but a relative lack of oxygen in Earth’s ancient oceans helped early marine creatures evolve, a new study claims. Indeed, the “Cambrian explosion”—the burst of evolution about 540 million years ago that included the birth of most of the major animal groups we know today—was enabled by oxygen deprivation, the researchers say. The finding comes in the wake of a better understanding of how oxygen levels in the oceans and the atmosphere fluctuated in the deep past, and may shift how scientists think animal evolution can proceed. [...]"

Source: Science Magazine
Author: Lucas Joel
DOI: 10.1126/science.aar5252

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Diverse Marinimicrobia bacteria may mediate coupled biogeochemical cycles along eco-thermodynamic gradients

Abstract.

"Microbial communities drive biogeochemical cycles through networks of metabolite exchange that are structured along energetic gradients. As energy yields become limiting, these networks favor co-metabolic interactions to maximize energy disequilibria. Here we apply single-cell genomics, metagenomics, and metatranscriptomics to study bacterial populations of the abundant “microbial dark matter” phylum Marinimicrobia along defined energy gradients. [...]"

Source: Nature Communications
Authors: Alyse K. Hawley et al.
DOI: 10.1038/s41467-017-01376-9

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A Three-Dimensional Mapping of the Ocean Based on Environmental Data

Abstract.

"The existence, sources, distribution, circulation, and physicochemical nature of macroscale oceanic water bodies have long been a focus of oceanographic inquiry. Building on that work, this paper describes an objectively derived and globally comprehensive set of 37 distinct volumetric region units, called ecological marine units (EMUs). They are constructed on a regularly spaced ocean point-mesh grid, from sea surface to seafloor, and attributed with data from the 2013 World Ocean Atlas version 2. The point attribute data are the means of the decadal averages from a 57-year climatology of six physical and chemical environment parameters (temperature, salinity, dissolved oxygen, nitrate, phosphate, and silicate). [...]"

Source: Oceanography
Authors: Roger G. Sayre
DOI: 10.5670/oceanog.2017.116

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Abyssal ocean overturning shaped by seafloor distribution

Abstract.

"The abyssal ocean is broadly characterized by northward flow of the densest waters and southward flow of less-dense waters above them. Understanding what controls the strength and structure of these interhemispheric flows—referred to as the abyssal overturning circulation—is key to quantifying the ocean’s ability to store carbon and heat on timescales exceeding a century. [...]"

Source: Nature
Authors: C. de Lavergne et al.
DOI: 10.1038/nature24472

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Mysterious ‘shadow zone’ traps 2000-year-old water

"A MYSTERIOUS abyss in the ocean known as the “shadow zone” traps ancient water dating back to 400AD. We now know why it’s there.
 

IT’S called the “shadow zone” and it lies around two kilometres below the surface in an ocean abyss where trapped water dates back to the fourth century.

This ancient water, which is between 1000 and 2000 years old, dates back to when the ancient Germanic tribe the Goths instigated the end of the Western Roman Empire and the rise of Medieval Europe. [...]"

Source: new.com.au

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M/V Columbia starts its study of ocean acidification

"An Alaska state ferry recently started work doubling as an ocean research platform.

The M/V Columbia, which conducts weekly runs between Bellingham, Washington and Alaska, has been installed with a seawater monitoring system to study ocean acidification, a byproduct of human-caused climate change which could affect sea life in Alaska and around the world. [...]"

Source: Juneau Empire

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Climate and anthropogenic controls of coastal deoxygenation on interannual to centennial timescales

Abstract.

"Understanding dissolved oxygen variability in the ocean is limited by the short duration of direct measurements, however sedimentary oxidation-reduction reactions can provide context for modern observations. Here we use bulk sediment redox-sensitive metal enrichment factors (MoEF, ReEF, and UEF) and scanning X-ray fluorescence (XRF) records to examine annual-scale sedimentary oxygen concentrations in the Santa Barbara Basin from the Industrial Revolution (AD ~1850) to present. [...]"

Source: Geophysical Research Letters
Authors: Yi Wang, Ingrid Hendy, Tiffany J. Napier
DOI: 10.1002/2017GL075443

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The Northern Gulf of Mexico During OAE2 and the Relationship Between Water Depth and Black Shale Development

Abstract.

"Despite their name, Oceanic Anoxic Events (OAEs) are not periods of uniform anoxia and black shale deposition in ancient oceans. Shelf environments account for the majority of productivity and organic carbon burial in the modern ocean, and this was likely true in the Cretaceous as well. However, it is unlikely that the mechanisms for such an increase were uniform across all shelf environments. [...]"

Source: Paleoceanography
Authors: Christopher M. Lowery
DOI: 10.1002/2017PA003180

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Hydrography in the Mediterranean Sea during a cruise with RV Tethys 2 in May 2015

Abstract.

"We report on data from an oceanographic cruise, covering western, central and eastern parts of the Mediterranean Sea, on the French research vessel Tethys 2 in May 2015. This cruise was fully dedicated to the maintenance and the metrological verification of a biogeochemical observing system based on a fleet of BGC-Argo floats. During the cruise, a comprehensive dataset of parameters sensed by the autonomous network was collected. [...]"

Source: Earth System Science Data (unter review)
Authors: Vincent Taillandier et al.
DOI: 10.5194/essd-2017-119

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A dynamic microbial community with high functional redundancy inhabits the cold, oxic subseafloor aquifer

Abstract.

"The rock-hosted subseafloor crustal aquifer harbors a reservoir of microbial life that may influence global marine biogeochemical cycles. Here we utilized metagenomic libraries of crustal fluid samples from North Pond, located on the flanks of the Mid-Atlantic Ridge, a site with cold, oxic subseafloor fluid circulation within the upper basement to query microbial diversity. [...]"

Source: The ISME Journal
Authors: Benjamin J. Tully et al.
DOI: 10.1038/ismej.2017.187

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