Multiple episodes of extensive marine anoxia linked to global warming and continental weathering following the latest Permian mass extinction
"Explaining the ~5-million-year delay in marine biotic recovery following the latest Permian mass extinction, the largest biotic crisis of the Phanerozoic, is a fundamental challenge for both geological and biological sciences. Ocean redox perturbations may have played a critical role in this delayed recovery. However, the lack of quantitative constraints on the details of Early Triassic oceanic anoxia (for example, time, duration, and extent) leaves the links between oceanic conditions and the delayed biotic recovery ambiguous. [...]"
Source: Science Advances
Authors: Feifei Zhan et al.
Read the full article here.
Ocean euxinia and climate change "double whammy" drove the Late Ordovician mass extinction
"The Late Ordovician mass extinction (LOME, ca. 445 Ma) was the first of the "Big Five" Phanerozoic extinction events and comprised two extinction pulses. Proposed kill mechanisms include glacially induced global cooling and the expansion of water-column anoxia and/or euxinia (sulfidic conditions), but no general consensus has been reached with regard to the precise role of these mechanisms. [...]"
Authors: Caineng Zou et al.
A model for the oceanic mass balance of rhenium and implications for the extent of Proterozoic ocean anoxia
"Emerging geochemical evidence suggests that the atmosphere-ocean system underwent a significant decrease in O2 content following the Great Oxidation Event (GOE), leading to a mid-Proterozoic ocean (ca. 2.0–0.8 Ga) with oxygenated surface waters and predominantly anoxic deep waters. The extent of mid-Proterozoic seafloor anoxia has been recently estimated using mass-balance models based on molybdenum (Mo), uranium (U), and chromium (Cr) enrichments in organic-rich mudrocks (ORM). [...]"
Source: Geochimica et Cosmochimica Acta
Authors: Alex I.Sheen et al.
Ocean Deoxygenation Conference Deadline
This is a quick reminder that the abstract submission deadline for the Ocean Deoxygenation Conference ends tomorrow Saturday, 14th April 2018 at 23.59h.
The hunt for the most-wanted chemolithoautotrophic spookmicrobes
"Microorganisms are the drivers of biogeochemical methane and nitrogen cycles. Essential roles of chemolithoautotrophic microorganisms in these cycles were predicted long before their identification. Dedicated enrichment procedures, metagenomics surveys and single-cell technologies have enabled the identification of several new groups of most-wanted spookmicrobes, including novel methoxydotrophic methanogens that produce methane from methylated coal compounds and acetoclastic ‘Candidatus Methanothrix paradoxum’, which is active in oxic soils. [...]"
Source: FEMS Microbiology Ecology
Authors: Michiel H in ‘t Zandt et al.
Latitudinal variations of δ30Si and δ15N signatures along the Peruvian shelf:
quantifying the effects of nutrient utilization versus denitrification over the past 600 years
"The sedimentary stable nitrogen isotope compositions of bulk organic matter (δ15Nbulk) and silicon isotope composition of diatoms (δ30SiBSi) both mainly reflect the degree of past nutrient utilization by primary producers. However, in ocean areas where anoxic and suboxic conditions prevail, the δ15Nbulk signal ultimately recorded within the sediments is also influenced by water column denitrification causing an increase in the subsurface δ15N signature of dissolved nitrate (δ15NO3−) upwelled to the surface. [...]"
Authors: Kristin Doering et al.
New Study in Oxygen-Deprived Black Sea Provides Insights on Future Carbon Budget
"Scientists are studying the oxygen-deprived waters of the Black Sea to help answer questions about the deepest parts of the ocean and Earth’s climate.
A new study led by researchers at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science found that even in the absence of oxygen, the chemical and biological processes occurring in the Black Sea resemble those in the oxygenated deep ocean. [...]"
Source: University of Miami Rosenstiel School of Marine & Atmospheric Science
Local oceanographic variability influences the performance of juvenile abalone under climate change
"Climate change is causing warming, deoxygenation, and acidification of the global ocean. However, manifestation of climate change may vary at local scales due to oceanographic conditions. Variation in stressors, such as high temperature and low oxygen, at local scales may lead to variable biological responses and spatial refuges from climate impacts. We conducted outplant experiments at two locations separated by ~2.5 km and two sites at each location separated by ~200 m in the nearshore of Isla Natividad, Mexico to assess how local ocean conditions (warming and hypoxia) may affect juvenile abalone performance. [...]"
Source: Scientific Reports
Authors: C.A. Boch
Species distribution modeling of deep sea sponges in the North Pacific Ocean.
"Knowledge of deep-sea species and their ecosystems is limited due to the inaccessibility of the areas and the prohibitive cost of conducting large-scale field studies. My graduate research has used predictive modeling methods to map hexactinellid sponge habitat extent in the North Pacific, as well as climate-induced changes in oceanic dissolved oxygen levels and how this will impact sponges. [...]"
Source: PeerJ (NOT PEER-REVIEWED)
Authors: Fiona Davidson
Ocean deoxygenation: Time for action
"In their Review "Declining oxygen in the global ocean and coastal waters" [...] D. Breitburg et al. summarize evidence showing that oxygen has declined in the open ocean and in coastal waters over the past 50 years as a result of increased greenhouse gas emissions and nutrient discharges to coastal waters. We also urgently need more data on the role and speed of microbial engagement, including how deoxygenation is altering microbial pathways and rates of processes within the water column and the deep ocean. [...]"
Authors: Sylvia A. Earle et al.