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. [...]"

Source: Biogeosciences
Authors: Kristin Doering et al.
DOI: 10.5194/bg-2018-118

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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

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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
DOI: 10.1038/s41598-018-23746-z

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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. [...]"

Authors: Fiona Davidson
DOI: 10.7287/peerj.preprints.26815v1

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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. [...]" 

Source: Science
Authors: Sylvia A. Earle et al.
DOI: 10.1126/science.aat0167

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Climate Change Projected to Exacerbate Impacts of Coastal Eutrophication in the Northern Gulf of Mexico


"The continental shelf in the northern Gulf of Mexico experiences expansive seasonal hypoxic conditions and eutrophication‐driven acidification in bottom waters. Rising surface ocean temperatures, freshwater and nutrient inputs, and atmospheric CO2 will further exacerbate these conditions. Using a high‐resolution, regional circulation‐biogeochemical model, we simulated the spatio‐temporal dynamics of oxygen and inorganic carbon in the northern Gulf of Mexico under present and a projected future (2100) climate state. [...]"

Source: Oceans (AGU Journal)
Authors: Arnaud Laurent et al.
DOI: 10.1002/2017JC013583

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NCCOS and NGI Lead Seventh Annual Hypoxia Research Coordination Workshop

"NCCOS is working with the Northern Gulf Institute (NGI) and Gulf of Mexico State partners to develop a robust and sustainable Gulf of Mexico-wide monitoring program for hypoxia. At the 7th Annual Hypoxia Research Coordination Workshop, planning continued for a Cooperative Hypoxia Assessment and Monitoring Program.

The Cooperative Hypoxia Assessment and Monitoring Program (CHAMP) is a bottom-up effort comprised of State (LA, AL/MS, TX) and issue-based workgroups. Eight workgroups (Fisheries, Louisiana-Mississippi/Alabama-Texas state monitoring, autonomous vehicles, Hypoxia Task Force, Oil/Gas and Ocean Acidification, and Gulf Restoration) identify and pursue leveraging and support opportunities within their local focus areas, benefiting the entire Gulf region. [...]"

Source: National Centers for Coastal Ocean Science (NCCOS)
Author: Alan Lewitus

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Gulf of Mexico dead zone not expected to shrink anytime soon

"Achieving water quality goals for the Gulf of Mexico may take decades, according to findings by researchers at the University of Waterloo.

The results, which appear in Science, suggest that policy goals for reducing the size of the northern Gulf of Mexico's dead zone may be unrealistic, and that major changes in agricultural and river management practices may be necessary to achieve the desired improvements in water quality.

The transport of large quantities of nitrogen from rivers and streams across the North American corn belt has been linked to the development of a large dead zone in the northern Gulf of Mexico, where massive algal blooms lead to oxygen depletion, making it difficult for marine life to survive.

"Despite the investment of large amounts of money in recent years to improve water quality, the area of last year's dead zone was more than 22,000 km2—about the size of the state of New Jersey," said Kimberly Van Meter, lead author of the paper and a postdoctoral fellow in the Department of Earth and Environmental Sciences at Waterloo. [...]"

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Global niche of marine anaerobic metabolisms expanded by particle microenvironments


"In ocean waters, anaerobic microbial respiration should be confined to the anoxic waters found in coastal regions and tropical oxygen minimum zones, where it is energetically favourable. However, recent molecular and geochemical evidence has pointed to a much broader distribution of denitrifying and sulfate-reducing microbes. [...]"

Source: Nature Geoscience
Authors: Daniele Bianchi et al.
DOI: 10.1038/s41561-018-0081-0

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Decreased oxygen levels could present hidden threat to marine species

"Scientists have shown that creatures which develop in hypoxic (low oxygen) conditions in the marine environment could experience previously unseen hindered development, and become compromised as adults. [...]

The prevalence of hypoxic (low oxygen) areas in coastal waters is predicted to increase in the future, both in terms of their scale and duration. And while the adults of many estuarine invertebrates can cope with short periods of hypoxia, it has previously been unclear whether that ability is present if animals are bred and reared under chronic hypoxia.[...]"

Source: (University of Plymouth)

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