黑料视频

Source: Wiley Online Library
Authors: Lia Domke et al.
DOI: 10.1111/maec.12481

Abstract

"Megafaunal diversity in the deep sea shows a parabolic pattern with depth. It can be affected by factors such as low oxygen concentration, which suppresses diversity, or the presence of submarine canyons, which enhances it. Barkley Canyon, located off the west coast of British Columbia, Canada, is a submarine canyon that extends from the continental margin (200 m) into the deep ocean (2,000 m). [...]."

Source: The Royal Society
Authors: Lillian R. McCormick & Lisa A. Levin
DOI: 10.1098/rsta.2016.0322

Abstract

"Climate change has induced ocean deoxygenation and exacerbated eutrophication-driven hypoxia in recent decades, affecting the physiology, behaviour and ecology of marine organisms. The high oxygen demand of visual tissues and the known inhibitory effects of hypoxia on human vision raise the questions if and how ocean deoxygenation alters vision in marine organisms. [...]."

Source: Wiley Online Library
Authors: Clara Mart铆nez-P茅rez et al.
DOI: 10.1111/1462-2920.14008

Abstract

"The N₂-fixing (diazotrophic) community in marine ecosystems is dominated by non-cyanobacterial microorganisms. Yet, very little is known about their identity, function and ecological relevance due to a lack of cultured representatives. Here we report a novel heterotrophic diazotroph isolated from the oxygen minimum zone (OMZ) off Peru. [...]."

Source: Wiley Online Library
Authors: G. Battaglia & F. Joos
DOI: 10.1002/2017GB005671

Abstract

"Nitrous oxide (N₂O) is a potent greenhouse gas (GHG) and ozone destructing agent, yet, global estimates of N₂O emissions are uncertain. Marine N₂O stems from nitrification and denitrification processes which depend on organic matter cycling and dissolved oxygen (O₂). We introduce N₂O as an obligate intermediate product of denitrification and as an O₂-dependent byproduct from nitrification in the Bern3D ocean model. [...]."

Source: ICES Journal of Marine Science
Authors: Kirk N Sato et al.
DOI: 10.1093/icesjms/fsx225

Abstract

"Marine fishery stakeholders are beginning to consider and implement adaptation strategies in the face of growing consumer demand and potential deleterious climate change impacts such as ocean warming, ocean acidification, and deoxygenation. This study investigates the potential for development of a novel climate change-tolerant sea urchin fishery in southern California based on Strongylocentrotus fragilis (pink sea urchin), a deep-sea species whose peak density was found to coincide with a current trap-based spot prawn fishery (Pandalus platyceros) in the 200鈥�300-m depth range. [...]."

Source: Philosophical Transactions of the Royal Society A
Authors: Andreas Oschlies et al.
DOI: 10.1098/rsta.2016.0325

Abstract

"Observational estimates and numerical models both indicate a significant overall decline in marine oxygen levels over the past few decades. Spatial patterns of oxygen change, however, differ considerably between observed and modelled estimates. Particularly in the tropical thermocline that hosts open-ocean oxygen minimum zones, observations indicate a general oxygen decline, whereas most of the state-of-the-art models simulate increasing oxygen levels. Possible reasons for the apparent model-data discrepancies are examined. [...]."

Source: Examines in Marine Biology and Oceanography
Authors: Baby Divya et al.
DOI: 10.31031/EIMBO.2017.01.000505

Abstract

"The eastern Arabian Sea has a unique and permanent oxygen minimum zone (OMZ) that extends along the western continental margin of India. In order to understand the bacterial community structure and diversity of OMZ sediment of the Arabian Sea (AS), PCR-DGGE analysis were carried out for samples collected off Ratnagiri, Goa and Karwar at 50m, 200m, 500m and 1000m depths. [...]."

Source: Phys.org
Authors: Ocean Networks Canada

"A new study led by Oregon State University (OSU) graduate student Sarah Seabrook that uses scientific data and samples from Ocean Networks Canada (ONC) focuses on the extent, variability, and complexity of species鈥攆rom microbes to tubeworms鈥攆ound at deep-sea cold seep habitats along the Cascadia fault off the west coast of North America. [...]."

Source: Wiley Online Library
Authors: Christopher M. Lowery et al.
DOI: 10.1002/2017PA003180

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. Some, like the northwest margin of Africa, were characterized by strong upwelling, but what might drive enhanced productivity on shelves not geographically suited for upwelling? [...]."

Source: Nature
Authors: Fr茅d茅ric A. C. Le Moigne et al.
DOI: 10.1038/s41598-017-16903-3

Abstract

"In marine oxygen (O₂) minimum zones (OMZs), the transfer of particulate organic carbon (POC) to depth via the biological carbon pump might be enhanced as a result of slower remineralisation under lower dissolved O₂ concentrations (DO). In parallel, nitrogen (N) loss to the atmosphere through microbial processes, such as denitrification and anammox, is directly linked to particulate nitrogen (PN) export. [...]."

Source: Environmental Monitor
Author: Mindy Cooper

"During the summer of 2017, researchers with the Louisiana Universities Marine Consortium (LUMCON) and Louisiana State University mapped the largest dead zone in the Gulf of Mexico to date. The Gulf of Mexico meets the shorelines of Alabama, Louisiana, Mississippi, Texas and western Florida and is home to a large fishing industry. Several rivers from the Midwestern watershed flow south into the Gulf, carrying with them sediment, nutrient loads, and pollution from fossil fuel burning and wastewater systems. The problem isn鈥檛 new, but it is expanding. [...]."

Source: Nature 
Authors: Chen-Tung Arthur Chen et al. 
DOI: 10.1038/s41558-017-0003-y

Abstract

"Oceans worldwide are undergoing acidification due to the penetration of anthropogenic CO₂ from the atmosphere. The rate of acidification generally diminishes with increasing depth. Yet, slowing down of the thermohaline circulation due to global warming could reduce the pH in the deep oceans, as more organic material would decompose with a longer residence time. [...]."

Source: Springer Link
Authors: Aziz Ur Rahman Shaik et al.
DOI: 10.1007/s10661-017-6344-1

Abstract

"The present study investigated the impacts of treated effluent discharge on physicochemical and biological properties of coastal waters from three pharmaceuticals situated along the coast of Visakhapatnam (SW Bay of Bengal). Seawater samples were collected (during the months of December 2013, March 2014 and April 2014) from different sampling locations (Chippada (CHP), Tikkavanipalem (TKP) and Nakkapalli (NKP)) at 0- and 30-m depths within 2-km radius (0.5 km = inner, 1 km = middle and 2 km鈥�=鈥塷uter sampling circles) from the marine outfall points. [...]."

Source: Nature
Authors: A.W. Jacobel et al.
DOI: 10.1038/s41467-017-01938-x

Abstract

"As the largest reservoir of carbon exchanging with the atmosphere on glacial鈥搃nterglacial timescales, the deep ocean has been implicated as the likely location of carbon sequestration during Pleistocene glaciations. Despite strong theoretical underpinning for this expectation, radiocarbon data on watermass ventilation ages conflict, and proxy interpretations disagree about the depth, origin and even existence of the respired carbon pool. [...]."

Source: Nature
Authors: Cole T. Edwards
DOI: 10.1038/s41561-017-0006-3

Abstract

"The largest radiation of Phanerozoic marine animal life quadrupled genus-level diversity towards the end of the Ordovician Period about 450 million years ago. A leading hypothesis for this Great Ordovician Biodiversification Event is that cooling of the Ordovician climate lowered sea surface temperatures into the thermal tolerance window of many animal groups, such as corals. [...]."

Source: Wiley Online Library
Authors: Karin E. Limburg et al. 
DOI: 10.1002/fee.1728

Abstract

"Many take for granted low oxygen as 鈥渏ust another water-quality issue鈥�. Excessive loads of nutrients from non-point and point sources, including sewage, enter aquatic ecosystems where they increase biological oxygen demand and promote eutrophic conditions that can lead to periods of hypoxia or anoxia (in coastal areas somewhat misnamed as 鈥渄ead zones鈥�). [...]."

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

"Animals need oxygen to survive, but a relative lack of oxygen in Earth鈥檚 ancient oceans helped early marine creatures evolve, a new study claims. Indeed, the 鈥淐ambrian explosion鈥濃�攖he burst of evolution about 540 million years ago that included the birth of most of the major animal groups we know today鈥攚as 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: Nature 
Authors: Alyse K. Hawley et al.
DOI: 10.1038/s41467-017-01376-9

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 鈥渕icrobial dark matter鈥� phylum Marinimicrobia along defined energy gradients. [...]."

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

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

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鈥攔eferred to as the abyssal overturning circulation鈥攊s key to quantifying the ocean鈥檚 ability to store carbon and heat on timescales exceeding a century. [...]."

Source: news.com.au
Author: Candace Sutton

"A MYSTERIOUS abyss in the ocean known as the 鈥渟hadow zone鈥� traps ancient water dating back to 400AD. We now know why it鈥檚 there. IT鈥橲 called the 鈥渟hadow zone鈥� 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: Juneau Empire

"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: Wiley Online Library
Authors: Yi Wang et al. 
DOI: 10.1002/2017GL075443

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 (Mo_EF, Re_EF, and U_EF) 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: Wiley Online Library
Authors: Christopher M. Lowery et al. 
DOI: 10.1002/2017PA003180

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: Oxford University Press
Authors: Benjamin J. Tully et al.
DOI: 10.1038/ismej.2017.187

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: University of British Columbia (media contact: Chris Balma)

"Canadian and US Department of Energy researchers have released 50 years鈥� worth of data chronicling the deoxygenating cycles of a fjord off Canada鈥檚 west coast, and detailing the response of the microbial communities inhabiting the fjord. The mass of data, collected in two new Nature family papers, could help scientists better predict the impact of human activities and ocean deoxygenation on marine environments. Currently, oxygen minimum zones (OMZs) constitute up to 7 percent of global ocean volume. Continued expansion of OMZs in the northeastern subarctic Pacific has the potential to transport oxygen-depleted waters into coastal regions, adversely affecting nutrient cycles and fisheries productivity. [...]."

Source: Biogeosciences
Authors: Michelle I. Graco et al.
DOI: 10.5194/bg-14-4601-2017

Abtract

"Over the last decades, the Humboldt Current upwelling ecosystem, particularly the northern component off the coast of Peru, has drawn the interest of the scientific community because of its unique characteristics: it is the upwelling system with the biggest catch productivity despite the fact it is embedded in a shallow and intense oxygen minimum zone (OMZ). [...]."

Source: Nature
Authors: Steven J. Hallam et al.
DOI: 10.1038/sdata.2017.158

Abstract

"Today in Scientific Data, two compendia of geochemical and multi-omic sequence information (DNA, RNA, protein) generated over almost a decade of time series monitoring in a seasonally anoxic coastal marine setting are presented to the scientific community. These data descriptors introduce a model ecosystem for the study of microbial responses to ocean deoxygenation, a phenotype that is currently expanding due to climate change. [...]."

Source: The Independent Barents Observer
Author: Levon Sevunts

"Ocean acidification combined with warming of the world oceans and loss of oxygen is having a severe impact on key Arctic marine species such as polar cod in the Barents Sea, according to a new study conducted by German scientists. [...]." 

Source: EurekAlert

"As a gigantic carbon sink, the ocean has taken up about a third of the carbon dioxide (CO2) released into the atmosphere by human activities. But when absorbed by seawater, the greenhouse gas triggers chemical reactions, causing the ocean to acidify. Ocean acidification affects ecosystems and important services the ocean provides to humankind. This includes the regulation of the Earth's climate, food provision, recreation as well as biodiversity as a condition for intact and functioning ecosystems. [...]."

Source: Wiley Online Library
Authors: D. Espinoza-Morriber贸n et al.
DOI: 10.1002/2016JC012439

Abstract

"Every 2鈥�7 years, El Ni帽o events trigger a strong decrease in phytoplankton productivity off Peru, which profoundly alters the environmental landscape and trophic chain of the marine ecosystem. Here we use a regional coupled physical-biogeochemical model to study the dynamical processes involved in the productivity changes during El Nino, with a focus on the strongest events of the 1958鈥�2008 period. Model evaluation using satellite and in situ observations shows that the model reproduces the surface and subsurface interannual physical and biogeochemical variability. [...]."

Source: Biogeosciences
Authors: Alexander Gal谩n et al.
DOI: 10.5194/bg-14-4795-2017

Abstract

"The upwelling system off central Chile (36.5掳鈥疭) is seasonally subjected to oxygen (O₂)-deficient waters, with a strong vertical gradient in O₂ (from oxic to anoxic conditions) that spans a few metres (30鈥�50鈥痬 interval) over the shelf. This condition inhibits and/or stimulates processes involved in nitrogen (N) removal (e.g. anammox, denitrification, and nitrification). During austral spring (September 2013) and summer (January 2014), the main pathways involved in N loss and its speciation, in the form of N₂ and/or N₂O, were studied using ¹⁵N-tracer incubations, inhibitor assays, and the natural abundance of nitrate isotopes along with hydrographic information. [...]."

Source: Wiley Online Library 
Authors: Muchamad Al Azhar et al. 
DOI: 10.1002/2017GL075157

Abstract

"The combination of high primary productivity and weak ventilation in the Arabian Sea (AS) and Bay of Bengal (BoB) generates vast areas of depleted oxygen, known as Oxygen Minimum Zones (OMZs). The AS OMZ is the world's thickest and hosts up to 40% of global denitrification. In contrast, the OMZ in the BoB is weaker and denitrification free. Using a series of model simulations, we show that the deeper remineralization depth (RD) in the BoB, potentially associated with organic matter aggregation with riverine mineral particles, contributes to weaken its OMZ. [...]."

Source: The Atlantic
Author:  Sarah Zhang

"The rain began on August 25, and it would fall, remarkably, for four more days. We know now that Hurricane Harvey dumped as much as 60 inches of rain over parts of Texas. Twenty trillion gallons in all. The equivalent of the entire Chesapeake Bay. Enough to push the Earth鈥檚 crust down two centimeters. [...]."

Source: Science 
Authors: Rocio I. Ruiz-Cooley et al.
DOI: 10.1126/sciadv.1701140

"Climate variability alters nitrogen cycling, primary productivity, and dissolved oxygen concentration in marine ecosystems. We examined the role of this variability (as measured by six variables) on food chain length (FCL) in the California Current (CC) by reconstructing a time series of amino acid鈥搒pecific 未¹⁵N values derived from common dolphins, an apex pelagic predator, and using two FCL proxies. [...]."

Source: Marine Ecology Progress Series
Authors: Laura M. Treible et al.
DOI: 10.3354/meps12298

Abstract

"Eutrophication-induced hypoxia is one of the primary anthropogenic threats to coastal ecosystems. Under hypoxic conditions, a deficit of O₂ and a surplus of CO₂ will concurrently decrease pH, yet studies of hypoxia have seldom considered the potential interactions with elevated pCO₂ (reduced pH). Previous studies on gelatinous organisms concluded that they are fairly robust to low oxygen and reduced pH conditions individually, yet the combination of stressors has only been examined for ephyrae. [...]."

Source: Mongabay
Author: Alexandra Popescu

"A more acidic ocean under climate change threatens to reconfigure entire ecosystems by advantaging some fish species to the detriment of others, a new study has found. The research is one of only a few that go beyond the lab to study how species interactions are changing in nature under more extreme conditions. [...]."

Source: Nature
Authors: Myrina Boulais et al.
DOI: 10.1038/s41598-017-13480-3

Abstract

"Atmospheric carbon dioxide concentrations have been rising during the past century, leading to ocean acidification (OA). Coastal and estuarine habitats experience annual pH variability that vastly exceeds the magnitude of long-term projections in open ocean regions. Eastern oyster (Crassostrea virginica) reproduction season coincides with periods of low pH occurrence in estuaries, thus we investigated effects of moderate [...] and severe OA [...] on oyster gametogenesis, fertilization, and early larval development successes. [...]."

Source: Wiley Online Library 
Authors: Xianbiao Lin et al.
DOI: 10.1002/2017JG004036

Abstract

"Global reactive nitrogen (N) has increased dramatically in coastal marine ecosystems over the past decades and caused numerous eco-environmental problems. Coastal marine sediment plays a critical role in N losses via denitrification and anaerobic ammonium oxidation (anammox) and release of nitrous oxide (N₂O). However, both the magnitude and contributions of denitrification, anammox, and N₂O production in sediments still remain unclear, causing uncertainty in defining the N budget for coastal marine ecosystems. [...]."

Source: Nature
Authors: Stefano Bonaglia et al.
DOI: 10.1038/s41598-017-13263-w

Abstract

"Methane and nitrous oxide are potent greenhouse gases (GHGs) that contribute to climate change. Coastal sediments are important GHG producers, but the contribution of macrofauna (benthic invertebrates larger than 1 mm) inhabiting them is currently unknown. Through a combination of trace gas, isotope, and molecular analyses, we studied the direct and indirect contribution of two macrofaunal groups, polychaetes and bivalves, to methane and nitrous oxide fluxes from coastal sediments. [...]."

Source: Nature
Authors: N. Keul et al.
DOI: 10.1038/s41598-017-11708-w

Abstract

"Pteropods are among the first responders to ocean acidification and warming, but have not yet been widely explored as carriers of marine paleoenvironmental signals. In order to characterize the stable isotopic composition of aragonitic pteropod shells and their variation in response to climate change parameters, such as seawater temperature, pteropod shells (Heliconoides inflatus) were collected along a latitudinal transect in the Atlantic Ocean (31掳 N to 38掳 S). [...]."

Source: Taylor & Francis Online
Author: John A. Raven
DOI: 10.1080/09670262.2017.1362593

Abstract

"Anthropogenic inputs are increasing the CO₂ content of the atmosphere, and the CO₂ and total inorganic C in the surface ocean and, to a lesser degree, the deep ocean. The greenhouse effect of the increased CO₂ (and, to a lesser extent, other greenhouse gases) is very probably the major cause of present global warming. The warming increases temperature of the atmosphere and the surface ocean to a greater extent than the deep ocean, with shoaling of the thermocline, decreasing nutrient flux to the surface ocean where there is greater mean photosynthetic photon flux density. [...]."

Source: Mind Guild

"Every year, we see wildfires wreak havoc on large regions of the West United States, and each year scientists attempt to forecast exactly how bad the upcoming fire season is going to be by assessing things like weather, moisture levels, and a bevy of different factors. [...]."

Source: Nature 
Authors: Timothy Bush et al.
DOI: 10.1038/s41467-017-00912-x

Abstract

"Although regime shifts are known from various ecosystems, the involvement of microbial communities is poorly understood. Here we show that gradual environmental changes induced by, for example, eutrophication or global warming can induce major oxic-anoxic regime shifts. We first investigate a mathematical model describing interactions between microbial communities and biogeochemical oxidation-reduction reactions. [...]."

Source: Wiley Online Library 
Authors: Daoxun Sun et al.
DOI: 10.1002/2017GB005716

Abstract

"The concentration of dissolved oxygen (O₂) plays fundamental roles in diverse chemical and biological processes throughout the oceans. The balance between the physical supply and the biological consumption controls the O₂ level of the interior ocean, and the O₂ supply to the deep waters can only occur through deep convection in the polar oceans. [...]."

Source: Phys.org

"The new study tested the capacity of European sea bass to perform not just in typical seawater but also in low-oxygen level sea water. Researchers used a novel integrated respiratory assessment paradigm (IRAP) to screen both the fish's aerobic capacity and tolerance for low-oxygen (hypoxic) levels, grouping the fish into hypoxia tolerant and hypoxia sensitive phenotypic groups. They then exposed the fish to dispersed crude oil for 48 hours. [...]."

Source: Science Direct
Authors: YangfanZhang et al.
DOI: 10.1016/j.aquatox.2017.07.020

Abstract

"We tested the hypothesis that the chronic residual effects of an acute exposure of European sea bass (Dicentrarchus labrax) to chemically dispersed crude oil is manifest in indices of hypoxic performance rather than aerobic performance. Sea bass were pre-screened with a hypoxia challenge test to establish their incipient lethal oxygen saturation (ILOS), but on discovering a wide breadth for individual ILOS values (2.6鈥�11.0% O₂ saturation), fish were subsequently subdivided into either hypoxia sensitive (HS) or hypoxia tolerant (HT) phenotypes, traits that were shown to be experimentally repeatable. [...]."

Source: The New Humanitarian
Author: Matthew O. Berger

"The effects of ocean acidification on marine life have only become widely recognized in the past decade. Now researchers are rapidly expanding the scope of investigations into what falling pH means for ocean ecosystems. [...]."

Source: Wiley Online Library 
Authors: Jackson W. F. Chu & Katie S. P. Gale
DOI: 10.1002/lno.10370

Abstract

"Expansion of oxygen deficient waters (hypoxia) in the northeast Pacific Ocean (NEP) will have marked impacts on marine life. The response of the resident communities will be a function of their ecophysiological constraints in low oxygen, although this remains untested in the NEP due to a lack of integrative studies. Here, we combine in situ surveys and lab-based respirometry experiments were conducted on three indicator species [...] of seasonally hypoxic systems in the NEP to test if metabolic constraints determine distributions and energy sequestration in a hypoxic setting. [...]."

Source: Wiley Online Library 
Authors: Daniel Pauly & William W. L. Cheung
DOI: 10.1111/gcb.13831

Abstract

"One of the main expected responses of marine fishes to ocean warming is decrease in body size, as supported by evidence from empirical data and theoretical modeling. The theoretical underpinning for fish shrinking is that the oxygen supply to large fish size cannot be met by their gills, whose surface area cannot keep up with the oxygen demand by their three-dimensional bodies. [...]."

Source: Juniper Publishers 
Authors: Jianheng Zhang et al. 
DOI: 10.19080/OFOAJ.2017.04.555646

Abstract

"A broad spectrum of events that come under the category of macroalgal blooms are recognized world-wide as a response to elevated levels of eutrophication in coastal areas. In the Yellow Sea of China, green tides have consecutively occurred 10 years, which is considered as the world鈥檚 largest Ulva blooms. However, in recently years, golden tides caused by Sargassum seaweed have also been on the rapid rise, resulting in dramatic damage to the environment and economy again. [...]."

Source: Wiley Online Library 
Authors: Miranda C. Jones & William W. L. Cheung
DOI: 10.1111/gcb.13869

Abstract

"Marine species are being impacted by climate change and ocean acidification, although their level of vulnerability varies due to differences in species' sensitivity, adaptive capacity and exposure to climate hazards. Due to limited data on the biological and ecological attributes of many marine species, as well as inherent uncertainties in the assessment process, climate change vulnerability assessments in the marine environment frequently focus on a limited number of taxa or geographic ranges. [...]."

Source: Wiley Online Library 
Authors: R. Somavilla et al. 
DOI: 10.1002/2017JC013125

Abstract

"Ocean surface warming is commonly associated with a more stratified, less productive, and less oxygenated ocean. Such an assertion is mainly based on consistent projections of increased near-surface stratification and shallower mixed layers under global warming scenarios. However, while the observed sea surface temperature (SST) is rising at midlatitudes, the concurrent ocean record shows that stratification is not unequivocally increasing nor is MLD shoaling. [...]."

Source: Nature 
Authors: Alexander J. Dickson
DOI: 10.1038/ngeo3028

Abstract

"The expansion and contraction of sulfidic depositional conditions in the oceans can be tracked with the isotopic composition of molybdenum in marine sediments. However, molybdenum-isotope data are often subject to multiple conflicting interpretations. Here I present a compilation of molybdenum-isotope data from three time intervals: the Toarcian Oceanic Anoxic Event about 183 million years ago, Oceanic Anoxic Event 2 about 94 million years ago, and two early Eocene hyperthermal events from 56 to 54 million years ago. [...]."

Source: The Royal Society 
Authors: Erik A. Sperling et al.
DOI: 10.1098/rspb.2016.0637

Abstract

"Sharp increases in atmospheric CO₂ are resulting in ocean warming, acidification and deoxygenation that threaten marine organisms on continental margins and their ecological functions and resulting ecosystem services. The relative influence of these stressors on biodiversity remains unclear, as well as the threshold levels for change and when secondary stressors become important. [...]."

Source: Wiley Online Library 
Authors: K. A. S. Mislan et al.
DOI: 10.1111/gcb.13799

Abstract

"Oxygen concentrations are hypothesized to decrease in many areas of the ocean as a result of anthropogenically driven climate change, resulting in habitat compression for pelagic animals. The oxygen partial pressure, pO₂, at which blood is 50% saturated (P₅₀) is a measure of blood oxygen affinity and a gauge of the tolerance of animals for low ambient oxygen. Tuna species display a wide range of blood oxygen affinities (i.e., P₅₀ values) and therefore may be differentially impacted by habitat compression as they make extensive vertical movements to forage on subdaily time scales. [...]."

Source: Wiley Online Library 
Authors: Caitlin R. Keating-Bitonti & Jonathan L. Payne
DOI: 10.1111/maec.12430

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: ASM Journals
Authors: J. Cameron Thrash et al.
DOI: 10.1128/mBio.01017-17

Abstract

"Marine regions that have seasonal to long-term low dissolved oxygen (DO) concentrations, sometimes called 鈥渄ead zones,鈥� are increasing in number and severity around the globe with deleterious effects on ecology and economics. One of the largest of these coastal dead zones occurs on the continental shelf of the northern Gulf of Mexico (nGOM), which results from eutrophication-enhanced bacterioplankton respiration and strong seasonal stratification. [...]."

Source: Wiley Online Library 
Authors: Kyra H. Kim et al.
DOI: 10.1002/2017JG003943

Abstract

"Beach aquifers host a dynamic and reactive mixing zone between fresh and saline groundwater of contrasting origin and composition. Seawater, driven up the beachface by waves and tides, infiltrates into the aquifer and meets the seaward-discharging fresh groundwater, creating and maintaining a reactive intertidal circulation cell. Within the cell, land-derived nutrients delivered by fresh groundwater are transformed or attenuated. We investigated this process by collecting porewater samples from multi-level wells along a shore-perpendicular transect on a beach near Cape Henlopen, Delaware and analyzing solute and particulate concentrations. [...]."

Source: Science Direct
Authors: P. Grasse et al.
DOI: 10.1016/j.epsl.2017.07.022

Abstract

"The distribution of dissolved rare earth elements (REEs) and neodymium isotopes (蔚Nd) in the open ocean traces water mass mixing and provides information on lithogenic inputs to the source regions of the water masses. However, the processes influencing the REE budget at the ocean margins, in particular source and sink mechanisms, are not yet well quantified. In this study the first dissolved REE concentrations and Nd isotope compositions of seawater from the Panama Basin (RV Meteor cruise M90) in the Eastern Equatorial Pacific (EEP) are presented. The EEP is characterized by one of the world's largest oxygen minimum zones (OMZs). It is dominated by high particle fluxes that are expected to enhance the removal of REEs from the water column by scavenging. [...]."

Source: Wiley Online Library 
Authors: Jannes Koelling et al. 
DOI: 10.1002/2017GL073933

Abstract

"Measurements of near-surface oxygen (O₂) concentrations and mixed layer depth from the K1 mooring in the central Labrador Sea are used to calculate the change in column-integrated (0鈥�1700 m) O₂ content over the deep convection winter 2014/2015. During the mixed layer deepening period, November 2014 to April 2015, the oxygen content increased by 24.3 卤 3.4 mol m^鈭�2, 40% higher than previous results from winters with weaker convection. By estimating the contribution of respiration and lateral transport on the oxygen budget, the cumulative air-sea gas exchange is derived. [...]."

Source: phys.org

"The Labrador Sea in the North Atlantic is one of the few areas in the world ocean where cold, saline seawater sinks to large depths and forms deep water. This convection process also transports oxygen into the deep sea. A team of scientists from Scripps Institution of Oceanography (San Diego, California), Dalhousie University (Halifax, Canada) and 黑料视频 Helmholtz Centre for Ocean Research Kiel have now published the analysis of data obtained from the mooring K1 in the international scientific journal Geophysical Research Letters. [...]."

Source: Biogeosciences
Authors: Emma L. Cavan et al.
DOI: 10.5194/bg-14-177-2017

Abstract

"The efficiency of the ocean's biological carbon pump (BCP_eff 鈥� here the product of particle export and transfer efficiencies) plays a key role in the air鈥搒ea partitioning of CO₂. Despite its importance in the global carbon cycle, the biological processes that control BCP_eff are poorly known. We investigate the potential role that zooplankton play in the biological carbon pump using both in situ observations and model output. Observed and modelled estimates of fast, slow, and total sinking fluxes are presented from three oceanic sites: the Atlantic sector of the Southern Ocean, the temperate North Atlantic, and the equatorial Pacific oxygen minimum zone (OMZ). [...]."

Source: Geo Science World
Authors: Thomas Kuhn et al.
DOI: 10.1130/G39091.1

Abstract

"On the basis of heat-flow measurements, seismic mapping, and sediment pore-water analysis, we demonstrate widespread and efficient ventilation of the 18鈥�22 Ma oceanic crust of the northeast equatorial Pacific Ocean. Recharge and discharge appear to be associated with basement outcrops, including seamounts and north-south鈥搕rending faults, along which sediment cover thins out and volcanic rocks are exposed. Low-temperature hydrothermal circulation through the volcanic crust leads to the reduction of heat flow through overlying sediments, with measured heat-flow values that are well below those expected from conductive cooling curves for lithosphere of this age. [...]."

Source: Nature
Authors: Haijun Song et al.
DOI: 10.1038/s41467-017-00502-x

Abstract

"Banded iron formations were a prevalent feature of marine sedimentation ~3.8鈥�1.8 billion years ago and they provide key evidence for ferruginous oceans. The disappearance of banded iron formations at ~1.8 billion years ago was traditionally taken as evidence for the demise of ferruginous oceans, but recent geochemical studies show that ferruginous conditions persisted throughout the later Precambrian, and were even a feature of Phanerozoic ocean anoxic events. [...]."

Source: Eurek Alert 

"Zone of water 30 feet below surface is increasing in acidity, threatening shellfish.

A research team, led by University of Delaware professor Wei-Jun Cai, has identified a zone of water that is increasing in acidity in the Chesapeake Bay. The team analyzed little studied factors that play a role in ocean acidification (OA)--changes in water chemistry that threaten the ability of shellfish such as oysters, clams and scallops to create and maintain their shells, among other impacts. [...]."

Source: Nature 
Authors: Wei-Jun Cai et al. 
DOI: 10.1038/s41467-017-00417-7

Abstract

"The combined effects of anthropogenic and biological CO₂ inputs may lead to more rapid acidification in coastal waters compared to the open ocean. It is less clear, however, how redox reactions would contribute to acidification. Here we report estuarine acidification dynamics based on oxygen, hydrogen sulfide (H₂S), pH, dissolved inorganic carbon and total alkalinity data from the Chesapeake Bay, where anthropogenic nutrient inputs have led to eutrophication, hypoxia and anoxia, and low pH. [...]."

Source: Wiley Online Library 
Authors: Scott M. Durski et al.
DOI: 10.1002/2017JC013089

Abstract

"Observations have suggested a trend of decreasing dissolved oxygen (DO) and increasing spiciness in summertime mid-depth slope waters and bottom shelf waters along the United States west coast over the past 50 years, but they have also demonstrated a large amount of interannual and decadal variability. Shelf bottom water and slope water properties can be influenced by both local and remote effects, including changes in circulation or changes in the characteristics of the source waters supplying the region. [...]."

Source: Wiley Online Library 
Authors: Adam B. Jost et al.
DOI: 10.1002/2017GC006941

Abstract

"The end-Triassic extinction coincided with an increase in marine black shale deposition and biomarkers for photic zone euxinia, suggesting that anoxia played a role in suppressing marine biodiversity. However, global changes in ocean anoxia are difficult to quantify using proxies for local anoxia. Uranium isotopes (未²³⁸U) in CaCO₃ sediments deposited under locally well-oxygenated bottom waters can passively track seawater 未²³⁸U, which is sensitive to the global areal extent of seafloor anoxia due to preferential reduction of ²³⁸U(VI) relative to ²³⁵U(VI) in anoxic marine sediments. [...]."

Source: Wiley Online Library
Authors: L. Coppola et al.
DOI: 10.1002/2016JC012594

Abstract

"During the winter 2013, an intense observation and monitoring was performed in the north-western Mediterranean Sea to study deep water formation process that drives thermohaline circulation and biogeochemical processes (HYMEX SOP2 and DEWEX projects). To observe intensively and continuously the impact of deep convection on oxygen (O₂) ventilation, an observation strategy was based on the enhancement of the Argo-O₂ floats to monitor the offshore dense water formation area (DWF) in the Gulf of Lion prior to and at the end of the convective period (December 2012 to April 2013). [...]."

Source: Nature
Authors: Junpeng Zhang et al. 
DOI: 10.1038/s41598-017-07904-3

Abstract

"Recent studies have enhanced our understanding of the linkage of oxygenation and metazoan evolution in Early Cambrian time. However, little of this work has addressed the apparent lag of animal diversification and atmospheric oxygenation during this critical period of Earth history. This study utilizes the geochemical proxy and N isotope record of the Ediacaran鈥揅ambrian boundary preserved in intra-shelf basin, slope, and slope basin deposits of the Yangtze Sea to assess the ocean redox state during the Early Cambrian metazoan radiation. [...]."

Source: Wiley Online Library
Authors: Xin Sun et al. 
DOI: 10.1002/2017GL074355

Abstract

"Nitrite oxidation is an essential step in transformations of fixed nitrogen. The physiology of nitrite oxidizing bacteria (NOB) implies that the rates of nitrite oxidation should be controlled by concentration of their substrate, nitrite, and the terminal electron acceptor, oxygen. The sensitivities of nitrite oxidation to oxygen and nitrite concentrations were investigated using ¹⁵N tracer incubations in the Eastern Tropical North Pacific. Nitrite stimulated nitrite oxidation under low in situ nitrite conditions, following Michaelis-Menten kinetics, indicating that nitrite was the limiting substrate. [...]."

Source: Science Direct
Authors: Florian Scholz et al. 
DOI: https://doi.org/10.1016/j.gca.2017.06.048

Abstract

"The concentration and isotope composition of molybdenum (Mo) in sediments and sedimentary rocks are widely used proxies for anoxic conditions in the water column of paleo-marine systems. While the mechanisms leading to Mo fixation in modern restricted basins with anoxic and sulfidic (euxinic) conditions are reasonably well constrained, few studies have focused on Mo cycling in the context of open-marine anoxia. Here we present Mo data for water column particulate matter, modern surface sediments and a paleo-record covering the last 140,000 years from the Peruvian continental margin. Mo concentrations in late Holocene and Eemian (penultimate interglacial) shelf sediments off Peru range from 鈭�70 to 100 碌g g^鈭�1, an extent of Mo enrichment that is thought to be indicative of (and limited to) euxinic systems. [...]."

Source: Science
Authors: Chadlin M. Ostrander et al. 
DOI: 10.1126/sciadv.1701020

Abstract

"The rates of marine deoxygenation leading to Cretaceous Oceanic Anoxic Events are poorly recognized and constrained. If increases in primary productivity are the primary driver of these episodes, progressive oxygen loss from global waters should predate enhanced carbon burial in underlying sediments鈥攖he diagnostic Oceanic Anoxic Event relic. Thallium isotope analysis of organic-rich black shales from Demerara Rise across Oceanic Anoxic Event 2 reveals evidence of expanded sediment-water interface deoxygenation ~43 卤 11 thousand years before the globally recognized carbon cycle perturbation. [...]."

Source: phys.org

"A loss of oxygen in global ocean seawater 94 million years ago led to a mass extinction of marine life that lasted for roughly half a million years. Scientists have found several potential explanations for how the loss of oxygen happened. These could include enhanced volcanic activity, increased nutrients reaching the ocean, rising sea levels, and warming sea and surface temperatures. But to point a finger at any one cause (or several of them) requires knowing how fast the oxygen loss happened. A new technique, developed by Arizona State University graduate student Chad Ostrander with colleagues at Wood Hole Oceanographic Institution (WHOI) and Florida State University (FSU), has put a timetable on the oxygen loss associated with this major ocean extinction event, which is known to science as Oceanic Anoxic Event 2. [...]."

Source: Nature
Authors: Tara S. Schraga & James E. Cloern
DOI: 10.1038/sdata.2017.98

Abstract

"The U.S. Geological Survey (USGS) maintains a place-based research program in San Francisco Bay (USA) that began in 1969 and continues, providing one of the longest records of water-quality measurements in a North American estuary. Constituents include salinity, temperature, light extinction coefficient, and concentrations of chlorophyll-a, dissolved oxygen, suspended particulate matter, nitrate, nitrite, ammonium, silicate, and phosphate. [...]."

Source: The Royal Society
Author: Andrew Bakun
DOI: 10.1098/rsta.2016.0327

Abstract

"Ocean deoxygenation often takes place in proximity to zones of intense upwelling. Associated concerns about amplified ocean deoxygenation arise from an arguable likelihood that coastal upwelling systems in the world's oceans may further intensify as anthropogenic climate change proceeds. Comparative examples discussed include the uniquely intense seasonal Somali Current upwelling, the massive upwelling that occurs quasi-continuously off Namibia and the recently appearing and now annually recurring 鈥榙ead zone鈥� off the US State of Oregon. [...]."

Source: The Royal Society
Authors: John G. Shepherd et al. 
DOI: 10.1098/rsta.2017.0240

Abstract

"Changes of ocean ventilation rates and deoxygenation are two of the less obvious but important indirect impacts expected as a result of climate change on the oceans. They are expected to occur because of (i) the effects of increased stratification on ocean circulation and hence its ventilation, due to reduced upwelling, deep-water formation and turbulent mixing, (ii) reduced oxygenation through decreased oxygen solubility at higher surface temperature, and (iii) the effects of warming on biological production, respiration and remineralization. The potential socio-economic consequences of reduced oxygen levels on fisheries and ecosystems may be far-reaching and significant. [...]."

Source: Earth System Dynamics
Authors: Daniela Niemeyer et al. 
DOI: 10.5194/esd-8-357-2017

Abstract

"Observations indicate an expansion of oxygen minimum zones (OMZs) over the past 50 years, likely related to ongoing deoxygenation caused by reduced oxygen solubility, changes in stratification and circulation, and a potential acceleration of organic matter turnover in a warming climate. The overall area of ocean sediments that are in direct contact with low-oxygen bottom waters also increases with expanding OMZs. This leads to a release of phosphorus from ocean sediments. If anthropogenic carbon dioxide emissions continue unabated, higher temperatures will cause enhanced weathering on land, which, in turn, will increase the phosphorus and alkalinity fluxes into the ocean and therefore raise the ocean's phosphorus inventory even further. [...]."

Source: The Guardian

"The global meat industry, already implicated in driving global warming and deforestation, has now been blamed for fueling what is expected to be the worst 鈥渄ead zone鈥� on record in the Gulf of Mexico. Toxins from manure and fertiliser pouring into waterways are exacerbating huge, harmful algal blooms that create oxygen-deprived stretches of the gulf, the Great Lakes and Chesapeake Bay, according to a new report by Mighty, an environmental group chaired by former congressman Henry Waxman. [...]."

Source: National Oceanic and Atmospheric Administration (NOAA)

"Scientists have determined this year鈥檚 Gulf of Mexico 鈥渄ead zone,鈥� an area of low oxygen that can kill fish and marine life, is 8,776 square miles, an area about the size of New Jersey. It is the largest measured since dead zone mapping began there in 1985. [...]."

Source: PNAS
Authors: Donald Scavia et al.
DOI: 10.1073/pnas.1705293114 

Abstract

"A large region of low-dissolved-oxygen bottom waters (hypoxia) forms nearly every summer in the northern Gulf of Mexico because of nutrient inputs from the Mississippi River Basin and water column stratification. Policymakers developed goals to reduce the area of hypoxic extent because of its ecological, economic, and commercial fisheries impacts. However, the goals remain elusive after 30 y of research and monitoring and 15 y of goal-setting and assessment because there has been little change in river nitrogen concentrations. [...]."

Source: Nature 
Authors: Alexander B. Michaud et al.
DOI: 10.1038/ngeo2992

Abstract

"Aquatic habitats beneath ice masses contain active microbial ecosystems capable of cycling important greenhouse gases, such as methane (CH₄). A large methane reservoir is thought to exist beneath the West Antarctic Ice Sheet, but its quantity, source and ultimate fate are poorly understood. For instance, O₂ supplied by basal melting should result in conditions favourable for aerobic methane oxidation. Here we use measurements of methane concentrations and stable isotope compositions along with genomic analyses to assess the sources and cycling of methane in Subglacial Lake Whillans (SLW) in West Antarctica. [...]."

Source: PNAS
Authors: Haojia Ren et al.
DOI: 10.1073/pnas.1701315114

Abstract

"The continental shelves are the most biologically dynamic regions of the ocean, and they are extensive worldwide, especially in the western North Pacific. Their area has varied dramatically over the glacial/interglacial cycles of the last million years, but the effects of this variation on ocean biological and chemical processes remain poorly understood. Conversion of nitrate to N₂ by denitrification in sediments accounts for half or more of the removal of biologically available nitrogen (鈥渇ixed N鈥�) from the ocean. The emergence of continental shelves during ice ages and their flooding during interglacials have been hypothesized to drive changes in sedimentary denitrification. [...]."

Source: Wiley Online Library
Authors: Arvind Singh et al.
DOI: 10.1002/2017GL074218

Abstract

"Diazotrophic dinitrogen (N₂) fixation contributes ~76% to 鈥渘ew鈥� nitrogen inputs to the sunlit open ocean, but environmental factors determining N₂ fixation rates are not well constrained. Excess phosphate (phosphate鈥搉itrate/16 > 0) and iron availability control N₂ fixation rates in the eastern tropical North Atlantic (ETNA), but it remains an open question how excess phosphate is generated within or supplied to the phosphate-depleted sunlit layer. [...]."

Source: The New Humanitarian
Author: Todd Woody

"After years of talks, the U.N. has taken a major step toward an international treaty to preserve the biodiversity of the high seas to combat climate change, overfishing and plastic pollution. [...]."

Source: Nature
Authors: Amal Jayakuma et al.
DOI: 10.1038/ismej.2017.97

Abstract

"Biological nitrogen fixation (BNF) was investigated above and within the oxygen-depleted waters of the oxygen-minimum zone of the Eastern Tropical North Pacific Ocean. BNF rates were estimated using an isotope tracer method that overcame the uncertainty of the conventional bubble method by directly measuring the tracer enrichment during the incubations. Highest rates of BNF (~4鈥塶M鈥塪ay^鈭�1) occurred in coastal surface waters and lowest detectable rates (~0.2鈥塶M鈥塪ay^鈭�1) were found in the anoxic region of offshore stations. [...]."

Source: Wiley Online Library
Authors: A. Landolfi et al.
DOI: 10.1002/2017GB005633

Abstract

"There is currently no consensus on how humans are affecting the marine nitrogen (N) cycle, which limits marine biological production and CO₂ uptake. Anthropogenic changes in ocean warming, deoxygenation, and atmospheric N deposition can all individually affect the marine N cycle and the oceanic production of the greenhouse gas nitrous oxide (N₂O). However, the combined effect of these perturbations on marine N cycling, ocean productivity, and marine N₂O production is poorly understood. Here we use an Earth system model of intermediate complexity to investigate the combined effects of estimated 21st century CO₂ atmospheric forcing and atmospheric N deposition. [...]."

Source: Springer Link
Authors: Zhaoyang Song et al. 
DOI: 10.1007/s00382-016-3298-x

Abstract

"The El Ni帽o/Southern Oscillation (ENSO) is the leading mode of tropical Pacific interannual variability in the present-day climate. Available proxy evidence suggests that ENSO also existed during past climates, for example during the Pliocene extending from about 5.3 million to about 2.6 million years BP. Here we investigate the influences of the Panama Seaway closing and Indonesian Passages narrowing, and also of atmospheric carbon dioxide (CO₂) on the tropical Pacific mean climate and annual cycle, and their combined impact on ENSO during the Pliocene. [...]."

Source: Nature
Authors: Alba Mar铆a Mart铆nez-P茅rez et al.
DOI: 10.1038/s41598-017-05941-6

Abstract

"Despite of the major role ascribed to marine dissolved organic matter (DOM) in the global carbon cycle, the reactivity of this pool in the dark ocean is still poorly understood. Present hypotheses, posed within the size-reactivity continuum (SRC) and the microbial carbon pump (MCP) conceptual frameworks, need further empirical support. Here, we provide field evidence of the soundness of the SRC model. We sampled the high salinity core-of-flow of the Levantine Intermediate Water along its westward route through the entire Mediterranean Sea. At selected sites, DOM was size-fractionated in apparent high (aHMW) and low (aLMW) molecular weight fractions using an efficient ultrafiltration cell. [...]."

Source: PNAS
Authors: Emilio Garcia-Robledo et al.
DOI: 10.1073/pnas.1619844114

Abstract

"Oxygen availability drives changes in microbial diversity and biogeochemical cycling between the aerobic surface layer and the anaerobic core in nitrite-rich anoxic marine zones (AMZs), which constitute huge oxygen-depleted regions in the tropical oceans. The current paradigm is that primary production and nitrification within the oxic surface layer fuel anaerobic processes in the anoxic core of AMZs, where 30鈥�50% of global marine nitrogen loss takes place. Here we demonstrate that oxygenic photosynthesis in the secondary chlorophyll maximum (SCM) releases significant amounts of O₂ to the otherwise anoxic environment. [...]."

Source: Science Daily

"Using a combination of fossils and chemical markers, scientists have tracked how a period of globally low ocean-oxygen turned an Early Jurassic marine ecosystem into a stressed community inhabited by only a few species. [...]."

Source: UPI
Author: Todd Woody

"As delegates convene at the United Nations to work out an international treaty to preserve the biodiversity of the high seas, a new report underscores the need to protect the remote ocean. Scientists at Oxford University in the United Kingdom reviewed 271 research papers published between 2012 and 2017 and synthesized the latest data on the impact of climate change, fishing and pollution on the high seas. Their findings are not encouraging: Even the most distant reaches of the ocean are suffering from chemical and plastic contamination, a loss of biodiversity and the consequences of rising temperatures. [...]."

Source: Wiley Online Library
Authors: I.N. Shilova et al.
DOI: 10.1002/lno.10590

Abstract

"Nitrogen (N) is the major limiting nutrient for phytoplankton growth and productivity in large parts of the world's oceans. Differential preferences for specific N substrates may be important in controlling phytoplankton community composition. To date, there is limited information on how specific N substrates influence the composition of naturally occurring microbial communities. We investigated the effect of nitrate ( ), ammonium ( ), and urea on microbial and phytoplankton community composition (cell abundances and 16S rRNA gene profiling) and functioning (photosynthetic activity, carbon fixation rates) in the oligotrophic waters of the North Pacific Ocean. [...]."

Source: Nature
Authors: Theodore R. Them et al.
DOI: 10.1038/s41598-017-05307-y

Abstract

"Chemical weathering consumes atmospheric carbon dioxide through the breakdown of silicate minerals and is thought to stabilize Earth鈥檚 long-term climate. However, the potential influence of silicate weathering on atmospheric pCO₂ levels on geologically short timescales (10³鈥�10⁵ years) remains poorly constrained. Here we focus on the record of a transient interval of severe climatic warming across the Toarcian Oceanic Anoxic Event or T-OAE from an open ocean sedimentary succession from western North America. [...]."

Source: Ocean Science
Authors: Johannes Hahn et al.
DOI: 10.5194/os-13-551-2017

Abstract

"Repeat shipboard and multi-year moored observations obtained in the oxygen minimum zone (OMZ) of the eastern tropical North Atlantic (ETNA) were used to study the decadal change in oxygen for the period 2006鈥�2015. Along 23掳鈥疻 between 6 and 14掳鈥疦, oxygen decreased with a rate of 鈭�5.9鈥�卤鈥�3.5鈥�碌mol鈥痥g鈭�1 decade鈭�1 within the depth covering the deep oxycline (200鈥�400鈥痬), while below the OMZ core (400鈥�1000鈥痬) oxygen increased by 4.0鈥�卤鈥�1.6鈥�碌mol鈥痥g鈭�1 decade鈭�1 on average. The inclusion of these decadal oxygen trends in the recently estimated oxygen budget for the ETNA OMZ suggests a weakened ventilation of the upper 400鈥痬, whereas the ventilation strengthened homogeneously below 400鈥痬. [...]."

Source: Nature
Authors: D. S. Grundle et al.
DOI: 10.1038/s41598-017-04745-y

Abstract

"Nitrous oxide (N₂O) is a climate relevant trace gas, and its production in the ocean generally increases under suboxic conditions. The Atlantic Ocean is well ventilated, and unlike the major oxygen minimum zones (OMZ) of the Pacific and Indian Oceans, dissolved oxygen and N₂O concentrations in the Atlantic OMZ are relatively high and low, respectively. [...]."

Source: Wiley Online Library
Authors: Yasuhiko Naito et al.
DOI: 10.1002/ece3.3202

Abstract

"Little is known about the foraging behavior of top predators in the deep mesopelagic ocean. Elephant seals dive to the deep biota-poor oxygen minimum zone (OMZ) (>800 m depth) despite high diving costs in terms of energy and time, but how they successfully forage in the OMZ remains largely unknown. Assessment of their feeding rate is the key to understanding their foraging behavior, but this has been challenging. Here, we assessed the feeding rate of 14 female northern elephant seals determined by jaw motion events (JME) and dive cycle time to examine how feeding rates varied with dive depth, particularly in the OMZ. [...]."

Source: OPB
Author: Cassandra Profita

"Millions of tubular sea creatures called pyrosomes have taken over the Pacific Ocean in an unprecedented bloom that has scientists baffled. These bumpy, translucent organisms look like sea cucumbers that range in size from six inches to more than two feet long. But they鈥檙e actually made up of hundreds of tiny animals knit together with tissue into a filter-feeding cylinder. [...]."

Source: Frontiers in Microbiology
Authors: Hongyue Dang & Chen-Tung A. Chen
DOI: 10.3389/fmicb.2017.01246

Abstract

"Transformation and mobilization of bioessential elements in the biosphere, lithosphere, atmosphere and hydrosphere constitute the Earth's biogeochemical cycles, which are driven mainly by microorganisms through their energy and material metabolic processes. Without microbial energy harvesting from sources of light and inorganic chemical bonds for autotrophic fixation of inorganic carbon, there would not be sustainable ecosystems in the vast ocean. Although ecological energetics (eco-energetics) has been emphasized as a core aspect of ecosystem analyses and microorganisms largely control the flow of matter and energy in marine ecosystems, marine microbial communities are rarely studied from the eco-energetic perspective. [...]."

Source: National Oceanic and Atmospheric Administration (NOAA)

"Larger-than-average low and no oxygen area may affect the region鈥檚 shrimp fisheries.

Federal scientists forecast that this summer鈥檚 Gulf of Mexico dead zone 鈥� an area of low to no oxygen that can kill fish and other marine life 鈥� will be approximately 8,185 square miles, or about the size of New Jersey. This would be the third largest dead zone recorded since monitoring began 32 years ago 鈥� the average Gulf dead zone since then has been 5,309 square miles. [...]."

Source: Frontiers in Microbiology
Authors: Xin Sun et al. 
DOI: 10.3389/fmicb.2017.01183

Abstract

"The ozone-depleting and greenhouse gas, nitrous oxide (N2O), is mainly consumed by the microbially mediated anaerobic process, denitrification. N2O consumption is the last step in canonical denitrification, and is also the least O2 tolerant step. Community composition of total and active N2O consuming bacteria was analyzed based on total (DNA) and transcriptionally active (RNA) nitrous oxide reductase (nosZ) genes using a functional gene microarray. The total and active nosZ communities were dominated by a limited number of nosZ archetypes, affiliated with bacteria from marine, soil and marsh environments. [...]."

Source: U.S. Geological Survey

"Scientists expect this year鈥檚 summer Chesapeake Bay hypoxic or 鈥渄ead zone鈥� 鈥� an area of low to no oxygen that can kill fish and aquatic life 鈥� will be larger than average, approximately 1.89 cubic miles, or nearly the volume of 3.2 million Olympic-size swimming pools. Measurements for the Bay鈥檚 dead zone go back to 1950, and the 30-year mean maximum dead zone volume is 1.74 cubic miles. [...]."

Source: The Guardian
Author: Dyani Lewis 

"There鈥檚 trouble brewing in Tasmania鈥檚 waterways once again. In the 1980s, protests over the proposed Franklin River hydroelectric dam threw the Apple Isle鈥檚 conservation plight onto the national stage. This time, it is the state鈥檚 salmon farming industry that is under a cloud. The relatively young industry is worth over $700m a year and now outpaces all other farming activities on the island but environmental campaigners are worried about its impact on the region鈥檚 pristine waters. [...]."

Source: Current Biology
Authors: Laura A. Bristow et al. 
DOI: 10.1016/j.cub.2017.03.030

Abstract

"Phytoplankton form the basis of the marine food web and are responsible for approximately half of global carbon dioxide (CO2) fixation (鈭� 50 Pg of carbon per year). Thus, these microscopic, photosynthetic organisms are vital in controlling the atmospheric CO2 concentration and Earth鈥檚 climate. Phytoplankton are dependent on sunlight and their CO2-fixation activity is therefore restricted to the upper, sunlit surface ocean (that is, the euphotic zone). CO2 usually does not limit phytoplankton growth due to its high concentration in seawater. [...]."

Source: PLOS
Authors: Carolina Doya et al.
DOI: 10.1371/journal.pone.0176917

Abstract

"Knowledge of the processes shaping deep-sea benthic communities at seasonal scales in cold-seep environments is incomplete. Cold seeps within highly dynamic regions, such as submarine canyons, where variable current regimes may occur, are particularly understudied. Novel Internet Operated Vehicles (IOVs), such as tracked crawlers, provide new techniques for investigating these ecosystems over prolonged periods. In this study a benthic crawler connected to the NEPTUNE cabled infrastructure operated by Ocean Networks Canada was used to monitor community changes across 60 m² of a cold-seep area of the Barkley Canyon, North East Pacific, at ~890 m depth within an Oxygen Minimum Zone (OMZ). [...]."

Source: Science 
Author: Dag L. Aksnes et al.
DOI: 10.1126/sciadv.1602468

Abstract

"The deep scattering layer (DSL) is a ubiquitous acoustic signature found across all oceans and arguably the dominant feature structuring the pelagic open ocean ecosystem. It is formed by mesopelagic fishes and pelagic invertebrates. The DSL animals are an important food source for marine megafauna and contribute to the biological carbon pump through the active flux of organic carbon transported in their daily vertical migrations. They occupy depths from 200 to 1000 m at daytime and migrate to a varying degree into surface waters at nighttime. Their daytime depth, which determines the migration amplitude, varies across the global ocean in concert with water mass properties, in particular the oxygen regime, but the causal underpinning of these correlations has been unclear. [...]."

Source: Nature
Authors: F. Chan et al.
DOI: 10.1038/s41598-017-02777-y

Abstract

"The near-term progression of ocean acidification (OA) is projected to bring about sharp changes in the chemistry of coastal upwelling ecosystems. The distribution of OA exposure across these early-impact systems, however, is highly uncertain and limits our understanding of whether and how spatial management actions can be deployed to ameliorate future impacts. Through a novel coastal OA observing network, we have uncovered a remarkably persistent spatial mosaic in the penetration of acidified waters into ecologically-important nearshore habitats across 1,000鈥塳m of the California Current Large Marine Ecosystem. [...]."

Source: Frontiers in Microbiology
Authors: Darren J. Parris et al.
DOI: 10.3389/fmicb.2014.00543

Abstract

"Molecular surveys are revealing diverse eukaryotic assemblages in oxygen-limited ocean waters. These communities may play pivotal ecological roles through autotrophy, feeding, and a wide range of symbiotic associations with prokaryotes. We used 18S rRNA gene sequencing to provide the first snapshot of pelagic microeukaryotic community structure in two cellular size fractions (0.2鈥�1.6 渭m, >1.6 渭m) from seven depths through the anoxic oxygen minimum zone (OMZ) off northern Chile. Sequencing of >154,000 amplicons revealed contrasting patterns of phylogenetic diversity across size fractions and depths. Protist and total eukaryote diversity in the >1.6 渭m fraction peaked at the chlorophyll maximum in the upper photic zone before declining by ~50% in the OMZ. [...]."

Source: PNAS
Authors: Osvaldo Ulloa et al.
DOI: 10.1073/pnas.1205009109

Abstract

"Vast expanses of oxygen-deficient and nitrite-rich water define the major oxygen minimum zones (OMZs) of the global ocean. They support diverse microbial communities that influence the nitrogen economy of the oceans, contributing to major losses of fixed nitrogen as dinitrogen (N₂) and nitrous oxide (N₂O) gases. Anaerobic microbial processes, including the two pathways of N₂ production, denitrification and anaerobic ammonium oxidation, are oxygen-sensitive, with some occurring only under strictly anoxic conditions. The detection limit of the usual method (Winkler titrations) for measuring dissolved oxygen in seawater, however, is much too high to distinguish low oxygen conditions from true anoxia. [...]."

Source: Nature
Authors: Emma F. Camp et al. 
DOI: 10.1038/s41598-017-02383-y

Abstract

"Coral reefs are deteriorating under climate change as oceans continue to warm and acidify and thermal anomalies grow in frequency and intensity. In vitro experiments are widely used to forecast reef-building coral health into the future, but often fail to account for the complex ecological and biogeochemical interactions that govern reefs. Consequently, observations from coral communities under naturally occurring extremes have become central for improved predictions of future reef form and function. Here, we present a semi-enclosed lagoon system in New Caledonia characterised by diel fluctuations of hot-deoxygenated water coupled with tidally driven persistently low pH, relative to neighbouring reefs. Coral communities within the lagoon system exhibited high richness (number of species鈥�=鈥�20) and cover (24鈥�35% across lagoon sites). [...]."

Source: Nature
Authors: Sarah J. Baker et al.
DOI: 10.1038/ncomms15018

Abstract

"The Toarcian Oceanic Anoxic Event (T-OAE) was characterized by a major disturbance to the global carbon(C)-cycle, and depleted oxygen in Earth鈥檚 oceans resulting in marine mass extinction. Numerical models predict that increased organic carbon burial should drive a rise in atmospheric oxygen (pO₂) leading to termination of an OAE after 鈭�1鈥塎yr. Wildfire is highly responsive to changes in pO₂ implying that fire-activity should vary across OAEs. Here we test this hypothesis by tracing variations in the abundance of fossil charcoal across the T-OAE. [...]."

Source: EurekAlert
Contact: Alex Morrison

"Dramatic drops in oceanic oxygen, which cause mass extinctions of sea life, come to a natural end - but it takes about a million years. The depletion of oxygen in the oceans is known as "anoxia", and scientists from the University of Exeter have been studying how periods of anoxia end. They found that the drop in oxygen causes more organic carbon to be buried in sediment on the ocean floor, eventually leading to rising oxygen in the atmosphere which ultimately re-oxygenates the ocean."

Source: Frontiers in Marine Physiology
Authors: Juan C. Capaz et al.
DOI: 10.3389/fphys.2017.00344

Abstract

"The common cuttlefish (Sepia officinalis), a dominant species in the north-east Atlantic ocean and Mediterranean Sea, is potentially subject to hypoxic conditions due to eutrophication of coastal waters and intensive aquaculture. Here we initiate studies on the biochemical response to an anticipated level of hypoxia. Cuttlefish challenged for one hour at an oxygen level of 50% dissolved oxygen saturation showed a decrease in oxygen consumption of 37% associated with an 85% increase in ventilation rate. [...]."

Source: Frontiers in Marine Science
Authors: Anja Engel et al.
DOI: 10.3389/fmars.2017.00165

Abstract

"Despite the huge extent of the ocean鈥檚 surface, until now relatively little attention has been paid to the sea surface microlayer (SML) as the ultimate interface where heat, momentum and mass exchange between the ocean and the atmosphere takes place. Via the SML, large-scale environmental changes in the ocean such as warming, acidification, deoxygenation and eutrophication potentially influence cloud formation, precipitation and the global radiation balance. Due to the deep connectivity between biological, chemical and physical processes, studies of the SML may reveal multiple sensitivities to global and regional changes. [...]."

Source: Wiley Online Library
Authors: Yassir A. Eddebbar et al.
DOI: 10.1002/2017GB005630

Abstract

"Models and observations of Atmospheric Potential Oxygen (APO鈥夆墐鈥塐₂鈥�+鈥�1.1*颁翱₂) are used to investigate the influence of El Ni帽o Southern Oscillation (ENSO) on air-sea O₂ exchange. An atmospheric transport inversion of APO data from the Scripps flask network shows significant interannual variability in tropical APO fluxes that is positively correlated with the Ni帽o3.4 index, indicating anomalous ocean outgassing of APO during El Ni帽o. Hindcast simulations of the Community Earth System Model (CESM) and the Institut Pierre-Simon Laplace (IPSL) model show similar APO sensitivity to ENSO, differing from the Geophysical Fluid Dynamic Laboratory (GFDL) model, which shows an opposite APO response. [...]."

Source: Frontiers in Marine Science
Authors: Peter Stief et al.
DOI: 10.3389/fmars.2017.00152

Abstract

"Oxygen minimum zones (OMZs) in the ocean are of key importance for pelagic fixed-nitrogen loss (N-loss) through microbial denitrification and anaerobic ammonium oxidation (anammox). Recent studies document that zooplankton is surprisingly abundant in and around OMZs and that the microbial community associated with carcasses of a large copepod species mediates denitrification. Here, we investigate the complex N-cycling associated with sinking zooplankton carcasses exposed to the steep O2 gradient in a coastal OMZ (Golfo Dulce, Costa Rica). 15N-stable-isotope enrichment experiments revealed that the carcasses of abundant copepods and ostracods provide anoxic microbial hotspots in the pelagic zone by hosting intense anaerobic N-cycle activities even in the presence of ambient O2. [...]." 

Source: PNAS
Authors: John W. Pohlman et al.
DOI: 10.1073/pnas.1618926114

Abstract

"Continued warming of the Arctic Ocean in coming decades is projected to trigger the release of teragrams (1 Tg = 10⁶ tons) of methane from thawing subsea permafrost on shallow continental shelves and dissociation of methane hydrate on upper continental slopes. On the shallow shelves (<100 m water depth), methane released from the seafloor may reach the atmosphere and potentially amplify global warming. On the other hand, biological uptake of carbon dioxide (CO₂) has the potential to offset the positive warming potential of emitted methane, a process that has not received detailed consideration for these settings. Continuous sea鈭抋ir gas flux data collected over a shallow ebullitive methane seep field on the Svalbard margin reveal atmospheric CO₂ uptake rates (鈭�33,300 卤 7,900 渭mol m^鈭�2鈰卍^鈭�1) twice that of surrounding waters and 鈭�1,900 times greater than the diffusive sea鈭抋ir methane efflux (17.3 卤 4.8 渭mol m^鈭�2鈰卍^鈭�1). [...]."

Source: Springer Link
Authors: Andrey O. Koch et al. 
DOI: 10.1007/978-3-319-54571-4_9

Abstract

"Bottom hypoxia on the shelf in the Northeast Pacific is caused by different processes than coastal hypoxia related to riverine inputs. Hypoxia off the coast of Oregon is a naturally occurring process as opposed to the anthropogenically forced hypoxia found in many coastal environments (e.g., Gulf of Mexico shelf, Chesapeake Bay). Off Oregon, bottom hypoxia occurs in summers that have large upwelling-driven near-bottom transport of high nitrate, low dissolved oxygen (DO) waters onto the shelf. The combination of low DO and high nitrate provides initially low (but not hypoxic) DO conditions near the bottom, and nitrate fertilization of shelf surface waters, leading to substantial phytoplankton production. [...]."

Source: Nature
Authors: Hannah K Marchant et al.
DOI: 10.1038/ismej.2017.51

Abstract

"Nitrogen (N) input to the coastal oceans has increased considerably because of anthropogenic activities, however, concurrent increases have not occurred in open oceans. It has been suggested that benthic denitrification in sandy coastal sediments is a sink for this N. Sandy sediments are dynamic permeable environments, where electron acceptor and donor concentrations fluctuate over short temporal and spatial scales. The response of denitrifiers to these fluctuations are largely unknown, although previous observations suggest they may denitrify under aerobic conditions. We examined the response of benthic denitrification to fluctuating oxygen concentrations, finding that denitrification not only occurred at high O₂ concentrations but was stimulated by frequent switches between oxic and anoxic conditions. [...]."

Source: Frontiers in Marine Science
Authors: Luis E. Medina et al.
DOI: 10.3389/fmars.2017.00105

Abstract

"Little is still known of the impacts of protist grazing on bacterioplankton communities in the dark ocean. Furthermore, the accuracy of assessments of in situ microbial activities, including protist grazing, can be affected by sampling artifacts introduced during sample retrieval and downstream manipulations. Potential artifacts may be increased when working with deep-sea samples or samples from chemically unique water columns such as oxygen minimum zones (OMZs). OMZs are oxygen-depleted regions in the ocean, where oxygen concentrations can drop to <20 渭M. These regions are typically located near eastern boundary upwelling systems and currently occur in waters occupying below about 8% of total ocean surface area, representing ~1% of the ocean's volume. [...]."

Source: Biogeosciences
Authors: Johannes Karstensen et al.
DOI: 10.5194/bg-14-2167-2017

Abstract

"The temporal evolution of the physical and biogeochemical structure of an oxygen-depleted anticyclonic modewater eddy is investigated over a 2-month period using high-resolution glider and ship data. A weakly stratified eddy core (squared buoyancy frequency N²鈥�舛膲鈭尖�夆赌�0.1鈥�舛膲脳舛膲舛寞10^鈭�4鈥痵^鈭�2) at shallow depth is identified with a horizontal extent of about 70鈥痥m and bounded by maxima in N². The upper N² maximum (3鈥�5鈥�鈥壝椻�夆��10^鈭�4鈥痵^鈭�2) coincides with the mixed layer base and the lower N² maximum (0.4鈥�鈥壝椻�夆��10^鈭�4鈥痵^鈭�2) is found at about 200鈥痬 depth in the eddy centre. The eddy core shows a constant slope in temperature/salinity (T鈭�S) characteristic over the 2 months, but an erosion of the core progressively narrows down the T鈭�S range. The eddy minimal oxygen concentrations decreased by about 5鈥�碌mol鈥痥g^鈭�1in 2 months, confirming earlier estimates of oxygen consumption rates in these eddies. [...]."

Source: Springer Link
Authors: Chengjie Li et al. 
DOI: 10.1007/s11802-017-2933-4

Abstract

"The influence of dissolved oxygen on calcareous deposits formed under galvanostatic polarization mode was studied. When the dissolved oxygen concentration was less than 7 mg L^鈭�1, the cathodic protection potential showed a plateau at the initial polarization, and then quickly shifted negatively. While the dissolved oxygen was more than 9 mg L^鈭�1, the potential shifted negatively in a linear form. After 168 h of polarization, the final protection potential shifted negatively with the decreasing dissolved oxygen concentration.  The deposition progress was monitored by electrochemical impedance spectroscopy, and only one single loop was found in Nyquist diagram, indicating deposits of ineffective protectiveness precipitation under the experimental conditions. [...]."

Source: Wiley Online Library
Authors: Takamitsu Ito et al.
DOI: 10.1002/2017gl073613

Abstract

"Historic observations of dissolved oxygen (O₂) in the ocean are analyzed to quantify multi-decadal trends and variability from 1958 to 2015. Additional quality control is applied and the resultant oxygen anomaly field is used to quantify upper ocean O₂ trends at global and hemispheric scales. A widespread negative O₂ trend is beginning to emerge from the envelope of interannual variability. Ocean reanalysis data is used to evaluate relationships with changes in ocean heat content (OHC) and oxygen solubility (O_2,sat). Global O₂ decline is evident after the 1980s, accompanied by an increase in global OHC. [...]."

Source: Phys.org

"Increasing water temperatures are responsible for the accumulation of a chemical called nitrite in marine environments throughout the world, a symptom of broader changes in normal ocean biochemical pathways that could ultimately disrupt ocean food webs, according to new research from the University of Georgia. [...]."

Source: ACS Publications
Authors: Sylvia C. Schaefer & James T. Hollibaugh
DOI: 10.1021/acs.est.6b03483

Abstract

"Nitrification is a two-step process linking the reduced and oxidized sides of the nitrogen cycle. These steps are typically tightly coupled with the primary intermediate, nitrite, rarely accumulating in coastal environments. Nitrite concentrations can exceed 10 渭M during summer in estuarine waters adjacent to Sapelo Island, Georgia, U.S.A. Similar peaks at other locations have been attributed to decoupling of the two steps of nitrification by hypoxia; however, the waters around Sapelo Island are aerobic and well-mixed.  Experiments examining the response to temperature shifts of a nitrifying assemblage composed of the same organisms found in the field indicate that ammonia- and nitrite-oxidation become uncoupled between 20 and 30 掳C, leading to nitrite accumulation. [...]."

Source: Wiley Online Library
Authors: Mercedes Pozo Buil & Emanuele Di Lorenzo
DOI: 10.1002/2017GL072931

Abstract

"The oxygen of the source waters that feed the upwelling in the California Current System show prominent multi-decadal fluctuations that are not significantly correlated with the dominant modes of Pacific climate variability. By combining observations and ocean reanalysis products between 1950-2010, we show that decadal changes in oxygen are linked to subsurface salinity variability and primarily controlled by ocean circulation dynamics. We find that subsurface anomalies in the core of the North Pacific Current propagate the oxygen signal downstream into the coastal upwelling system following the path of the mean gyre circulation with a timescale of 10-years. [...]."

Source: Inter-Research Science Publisher
Authors: Sara Cernadas-Mart铆n et al.
DOI: 10.3354/ame01817

Abstract

"Depth distributions of cells and functional gene copies from anaerobic ammonium-oxidizing (anammox) bacteria, aerobic ammonium-oxidizing bacteria (AOB) and archaea (AOA) in the Cariaco Basin, Venezuela were obtained using FISH and q-PCR assays. These distributions were compared to concentrations of dissolved ammonium (NH₄⁺), nitrite (NO₂^-), nitrate (NO₃^-), hydrogen sulfide (H₂S) and oxygen (O₂) along the redoxcline during 3 cruises. Cell counts of anammox bacteria and copies of their nitrite reductase gene (Scalindua-nirS) were consistently observed in 2 distinct layers: the suboxic zone (鈮�1.1 脳 10⁶ cells l^-1) and the upper euxinic zone (鈮�4.7 脳 10⁶ cells l^-1). [...]."

Source: EOS
Author: Sarah Stanley

"For the first time, scientists provide a sea-wide view of what happens to Mediterranean waters that flow into the Black Sea through the Bosporus Strait. Below a depth of about 150 meters, the Black Sea is devoid of oxygen. Only certain microbes can survive in this 鈥渄ead zone,鈥� which reaches depths of over 2000 meters. Warm, salty water flowing from the Mediterranean Sea into the Black Sea ventilates the middepth water column of the sea, trapping anoxic water below and maintaining the sea鈥檚 distinctive structure. However, the precise fate of inflowing Mediterranean waters has remained something of a mystery to scientists. [...]."

Source: Frontiers in Marine Science
Authors: Christopher J. Somes et al.
DOI: 10.3389/fmars.2017.00108

Abstract

"Nitrogen is a key limiting nutrient that influences marine productivity and carbon sequestration in the ocean via the biological pump. In this study, we present the first estimates of nitrogen cycling in a coupled 3D ocean-biogeochemistry-isotope model forced with realistic boundary conditions from the Last Glacial Maximum (LGM) ~21,000 years before present constrained by nitrogen isotopes. The model predicts a large decrease in nitrogen loss rates due to higher oxygen concentrations in the thermocline and sea level drop, and, as a response, reduced nitrogen fixation. Model experiments are performed to evaluate effects of hypothesized increases of atmospheric iron fluxes and oceanic phosphorus inventory relative to present-day conditions. [...]."

Source: Biogeosciences 
Authors: Anja Engel et al.
DOI: 10.5194/bg-14-1825-2017

Abstract

"In the ocean, sinking of particulate organic matter (POM) drives carbon export from the euphotic zone and supplies nutrition to mesopelagic communities, the feeding and degradation activities of which in turn lead to export flux attenuation. Oxygen (O2) minimum zones (OMZs) with suboxic water layers (<鈥�5鈥�碌mol O2鈥痥g鈭�1) show a lower carbon flux attenuation compared to well-oxygenated waters (>鈥�100鈥�碌mol O2鈥痥g鈭�1), supposedly due to reduced heterotrophic activity. [...]."

Source: Science Direct
Authors: J.P. Navarro-Ramirez et al.
DOI: 10.1016/j.cretres.2017.03.009

Abstract

"Little is known about the impact of the mid-Cretaceous Oceanic Anoxic Events (OAEs) on the neritic carbonate systems in South America. In order to fill this knowledge gap, the present paper reports on the record of environmental changes in the Albian鈥揟uronian neritic carbonates from the western South American domain in Peru. Owing to the very expanded and well-exposed sections in the Oyon region of central Peru, the OAE 1d and 2 intervals were sampled at high temporal resolution for both bulk micrite and bulk organic matter carbon isotopes, allowing us to compare the fingerprint of these two events between the northern and central Peruvian regions. [...]."

Source: Biogeosciences
Authors: Lea Steinle et al.
DOI: 10.5194/bg-14-1631-2017

Abstract

"Coastal seas may account for more than 75鈥�% of global oceanic methane emissions. There, methane is mainly produced microbially in anoxic sediments from which it can escape to the overlying water column. Aerobic methane oxidation (MOx) in the water column acts as a biological filter, reducing the amount of methane that eventually evades to the atmosphere. The efficiency of the MOx filter is potentially controlled by the availability of dissolved methane and oxygen, as well as temperature, salinity, and hydrographic dynamics, and all of these factors undergo strong temporal fluctuations in coastal ecosystems. [...]."

Source: The Maui News

"A groundbreaking scientific data collection program to expand the measuring of water quality off 18 West Maui shoreline sites has been forged between the state Department of Health and Maui community groups involved in the protection of the island鈥檚 nearshore waters. [...]."

Source: Bioggeosciences
Authors: Parvathi Vallivattathillam et al.
DOI: 10.5194/bg-14-1541-2017

Abstract

"The seasonal upwelling along the west coast of India (WCI) brings nutrient-rich, oxygen-poor subsurface waters to the continental shelf, favoring very low oxygen concentrations in the surface waters during late boreal summer and fall. This yearly-recurring coastal hypoxia is more severe during some years, leading to coastal anoxia that has strong impacts on the living resources. In the present study, we analyze a 1/4鈼� resolution coupled physical鈥揵iogeochemical regional oceanic simulation over the 1960鈥�2012 period to investigate the physical processes influencing the oxycline interannual variability off the WCI, that being a proxy for the variability on the shelf in our model. [...]." 

Source: Science Direct 
Authors: Klaas G.J. Nierop et al. 
DOI: dx.doi.org/10.1016/j.gca.2017.02.032

Abstract

"The Arabian Sea represents a prime example of an open ocean extended oxygen minimum zone (OMZ) with low oxygen concentrations (down to less than 2 mM) between 200 and 1000 m water depth. The OMZ impinges on the ocean floor, affect ingorganic matter (OM) mineralization. We investigated impact of oxygen depletion on the composition of macromolecularOM (MOM) along a transect through the OMZ on the slopes of the Murray Ridge. This sub-marine high in the northern Arabian Sea, with the top at approximately 500 m below sea surface (mbss), intersects the OMZ. We analyzed sediments deposited in the core of OMZ (suboxic conditions) [...]."

Source: Nature 
Authors: E. L. Cavan et al. 
DOI: 10.1038/ncomms14847

Abstract

"Biological oceanic processes, principally the surface production, sinking and interior remineralization of organic particles, keep atmospheric CO₂ lower than if the ocean was abiotic. The remineralization length scale (RLS, the vertical distance over which organic particle flux declines by 63%, affected by particle respiration, fragmentation and sinking rates) controls the size of this effect and is anomalously high in oxygen minimum zones (OMZ). Here we show in the Eastern Tropical North Pacific OMZ 70% of POC remineralization is due to microbial respiration, indicating that the high RLS is the result of lower particle fragmentation by zooplankton, likely due to the almost complete absence of zooplankton particle interactions in OMZ waters. [...]."

Source: PNAS
Authors: Andrew H. Altieri et al.
DOI: 10.1073/pnas.1621517114

Abstract

"Degradation of coastal water quality in the form of low dissolved oxygen levels (hypoxia) can harm biodiversity, ecosystem function, and human wellbeing. Extreme hypoxic conditions along the coast, leading to what are often referred to as 鈥渄ead zones,鈥� are known primarily from temperate regions. However, little is known about the potential threat of hypoxia in the tropics, even though the known risk factors, including eutrophication and elevated temperatures, are common. [...]."

Source: Wiley Online Library
Authors: Richard E. Thomson et al.
DOI: 10.1002/2016JC012512

Abstract

"Shallow sills restrict the ventilation of deep coastal fjords. Dense oceanic water seaward of the sill and lower density water within the receiving basin are generally required for oxygenated water to cross the sill and descend deep into the fjord. Here, we use concurrent 10-year time series from current meters in the fjord and on the continental shelf to examine ventilation of the 120-m deep, anoxic inner basin of Effingham Inlet on the west coast of Vancouver Island. Whereas density currents traverse the 40 m-deep sill and flow into the inner basin at mid-depth at quasi-fortnightly tidal intervals, only five current intrusions descended to the bottom of the basin over the decade-long measurement period. [...]."

Source: Science
Authors: I. Halevy & A. Bachan
DOI: 10.1126/science.aal4151

Abstract

"Although pH is a fundamental property of Earth鈥檚 oceans, critical to our understanding of seawater biogeochemistry, its long-timescale geologic history is poorly constrained. We constrain seawater pH through time by accounting for the cycles of the major components of seawater. We infer an increase from early Archean pH values between ~6.5 and 7.0 and Phanerozoic values between ~7.5 and 9.0, which was caused by a gradual decrease in atmospheric pCO₂ in response to solar brightening, alongside a decrease in hydrothermal exchange between seawater and the ocean crust. [...]."

Source: Nature
Authors: Atsushi Kubo et al.
DOI: 10.1038/srep44355

Abstract

"Most estuaries and inland waters are significant source for atmospheric CO₂ because of input of terrestrial inorganic carbon and mineralization of terrestrially supplied organic carbon. In contrast to most coastal waters, some estuaries with small freshwater discharge are weak source or sometimes sink for CO₂. Extensive surveys of pCO₂ in Tokyo Bay showed that the overall bay acts as a strong net sink for atmospheric CO₂. Although small area was a consistent source for CO₂, active photosynthesis driven by nutrient loading from the land overwhelmed the CO₂ budget in the bay. [...]."

Source: National Centers for Coastal Ocean Science (NCCOS)
Primary Contact: David Hilmer

"We are integrating existing data sets collected in the Northern Gulf of Mexico to study hypoxia impacts on coastal ecosystems and associated fisheries. We are using probabilistic, data-centric modeling to assess the spatiotemporal dynamics of hypoxia and to understand and forecast fisheries and ecosystem impacts. Our research focuses on data-driven inferences driving hypoxia and fisheries dynamics, rigorous uncertainty quantification, and prudent forecasting methodologies for all coastal areas."

. 

Source: National Centers for Coastal Ocean Science (NCCOS)
Primary Contact: David Hilmer

"We are linking a suite of well-established models to quantify fish and shrimp population responses to combinations of nutrient loadings and planned river diversions. Our scenario analyses include different land-use and agricultural practices in the watershed and alternative river diversions. The linked model system informs and supports management decisions by estimating how reduced nutrients and diversion operations affect hypoxia and key living resources." 

.

Source: Nature
Authors: Mark J. Hopwood et al.
DOI: 10.1038/srep43436

Abstract

"Hydrogen peroxide (H₂O₂) is present ubiquitously in marine surface waters where it is a reactive intermediate in the cycling of many trace elements. Photochemical processes are considered the dominant natural H₂O₂ source, yet cannot explain nanomolar H₂O₂concentrations below the photic zone. Here, we determined the concentration of H2O2 in full depth profiles across three ocean basins (Mediterranean Sea, South Atlantic and South Pacific Oceans). To determine the accuracy of H₂O₂ measurements in the deep ocean we also re-assessed the contribution of interfering species to 鈥榓pparent H₂O₂鈥�, as analysed by the luminol based chemiluminescence technique. [...]." 

Source: Wiley Online Library
Authors: L. S谩nchez-Velasco et al.
DOI: 10.1002/2016JC012622

Abstract

"Based on hydrographic data and vertical distributions of tropical species of fish larvae (Diogenichthys laternatus, Vinciguerria lucetia, Bregmaceros bathymaster and Auxis spp), effects of 鈥淕odzilla El Ni帽o 2015-2016鈥� in the shallow oxygen minimum zone off Mexico were analyzed. Zooplankton samples were collected during four cruises, before (February 2010, April 2012) and during (June 2015, March 2016) the warm event. Temporal series of sea surface temperature revealed that June 2015 was the warmest June of the last years. Conservative Temperature was鈥�>鈥�2掳C higher than normal in the surface mixed layer, and the suboxic layer (4.4 碌mol/kg) reached as shallow as 100 m depth. [...]."

Source: Biogeosciences
Authors: Teresa Beaty et al.
DOI: 10.5194/bg-14-781-2017

Abstract

"Dissolved oxygen (DO) concentration in the ocean is an important component of marine biogeochemical cycles and will be greatly altered as climate change persists. In this study a global oceanic carbon cycle model (HAMOCC 2.0) is used to address how mechanisms of oxygen minimum zone (OMZ) expansion respond to changes in CO₂ radiative forcing. Atmospheric pCO₂ is increased at a rate of 1鈥�% annually and the model is stabilized at 2鈥�脳, 4鈥壝�, 6鈥�鈥壝�, and 8鈥壝椻�塸reindustrial pCO₂ levels. With an increase in CO₂ radiative forcing, the OMZ in the Pacific Ocean is controlled largely by changes in particulate organic carbon (POC) export, resulting in increased remineralization and thus expanding the OMZs within the tropical Pacific Ocean. [...]."

Source: Nature
Authors: Panagiota-Myrsini Chronopoulou et al.
DOI: 10.1038/ismej.2017.6

Abstract

"Oxygen minimum zones (OMZs) contain the largest pools of oceanic methane but its origin and fate are poorly understood. High-resolution (<15鈥塵) water column profiles revealed a 300鈥塵 thick layer of elevated methane (20鈥�105鈥塶m) in the anoxic core of the largest OMZ, the Eastern Tropical North Pacific. Sediment core incubations identified a clear benthic methane source where the OMZ meets the continental shelf, between 350 and 650鈥塵, with the flux reflecting the concentration of methane in the overlying anoxic water. [...]." 

Source: oceanblogs.org

The deep sea is the largest environment on the planet. Most of the deep sea consists of the water column above the seafloor, the pelagic zone. In many parts of the pelagic ocean, no scientific sample or observation has ever been collected. Consequently, knowledge on deep-sea pelagic biodiversity and on the biology and ecology of organisms in this realm remain largely unknown. During MSM61 we perform deployments with the pelagic in situ observation system or PELAGIOS. This ocean instrument collects high definition video during horizontal transects while being towed on a CTD cable at various depths of interest. [...]."

.

Source: The Guardian
Author: Nicola Davis

"New study reveals negative impact of climate change, human activity, acidification and deoxygenation on ocean and its creatures.
The deep ocean and the creatures that live there are facing a desperate future due to food shortages and changing temperatures, according to research exploring the impact of climate change and human activity on the world鈥檚 seas. [...]." 

Source: Nature
Authors: Shubham Tripathi et al.
DOI: 10.1038/srep43056

Abstract

"In the Arabian Sea, South Asian monsoon (SAM)-induced high surface water productivity coupled with poor ventilation of intermediate water results in strong denitrification within the oxygen minimum zone (OMZ). Despite the significance of denitrification in the Arabian Sea, we have no long-term record of its evolution spanning the past several million years. Here, we present the first record of denitrification evolution since Late Miocene (~10.2鈥塎a) in the Eastern Arabian Sea, where the SAM generates moderate surface water productivity, based on the samples retrieved during the International Ocean Discovery Program (IODP) Expedition 355. [...]."

Source: The Guardian
Author: Susan Smillie

"Oxygen levels in oceans have fallen 2% in 50 years due to climate change, affecting marine habitat and large fish such as tuna and sharks.
The depletion of oxygen in our oceans threatens future fish stocks and risks altering the habitat and behaviour of marine life, scientists have warned, after a new study found oceanic oxygen levels had fallen by 2% in 50 years. [...]." 

Source: Science Direct
Authors: Fabio C. De Leo et al.
DOI: 10.1016/j.dsr2.2016.11.014

Abstract

"Understanding responses of benthic ecosystems to cumulative impacts of natural stressors, long-term ocean change and increasing resource exploitation is an emerging area of interest for marine ecologists and environmental managers. Few, if any, studies have quantitatively addressed cumulative effects in the deep sea. We report here on a study from the continental slope off Vancouver Island (Canada) in the northeast Pacific Ocean, where the Oxygen Minimum Zone impinges on seabed habitats that are subjected to widespread bottom trawling, primarily by the fishery for thornyhead (Sebastolobus ssp.). We examined how the benthic megafauna in this area was influenced by varying levels of dissolved oxygen and trawling activity, along a depth gradient that was also likely to shape community composition. [...]."

Source: Nature
Authors: Sunke Schmidtko et al.
DOI: 10.1038/nature21399

Abstract

"Ocean models predict a decline in the dissolved oxygen inventory of the global ocean of one to seven per cent by the year 2100, caused by a combination of a warming-induced decline in oxygen solubility and reduced ventilation of the deep ocean. It is thought that such a decline in the oceanic oxygen content could affect ocean nutrient cycles and the marine habitat, with potentially detrimental consequences for fisheries and coastal economies. [...]."

Source: The Washington Post

"A large research synthesis, published in one of the world鈥檚 most influential scientific journals, has detected a decline in the amount of dissolved oxygen in oceans around the world 鈥� a long-predicted result of climate change that could have severe consequences for marine organisms if it continues. [...]."

Source: Science
Authors: Gerdhard L. Jessen et al.
DOI: 10.1126/sciadv.1601897

Abstract

"Bottom-water oxygen supply is a key factor governing the biogeochemistry and community composition of marine sediments. Whether it also determines carbon burial rates remains controversial. We investigated the effect of varying oxygen concentrations (170 to 0 渭M O₂) on microbial remineralization of organic matter in seafloor sediments and on community diversity of the northwestern Crimean shelf break. [...]."

Source: Phys.org

"Periodic oscillations of bottom-water oxygen concentrations can alter benthic communities and carbon storage for decades, reveals a new study published in Science Advances. This is particularly relevant as low oxygen conditions are on the rise in the world's oceans. [...]."

Source: PNAS
Authors: Guijie Zhang et al.
DOI: 10.1073/pnas.1610931114

Abstract

"The end-Permian mass extinction represents the most severe biotic crisis for the last 540 million years, and the marine ecosystem recovery from this extinction was protracted, spanning the entirety of the Early Triassic and possibly longer. Numerous studies from the low-latitude Paleotethys and high-latitude Boreal oceans have examined the possible link between ocean chemistry changes and the end-Permian mass extinction. However, redox chemistry changes in the Panthalassic Ocean, comprising 鈭�85鈥�90% of the global ocean area, remain under debate. Here, we report multiple S-isotopic data of pyrite from Upper Permian鈥揕ower Triassic deep-sea sediments of the Panthalassic Ocean, now present in outcrops of western Canada and Japan. [...]."

Source: Frontiers in Marine Science
Authors: Cory C. Padilla et al.
DOI: 10.3389/fmars.2017.00023

Abstract

"Diverse planktonic microorganisms play a crucial role in mediating methane flux from the ocean to the atmosphere. The distribution and composition of the marine methanotroph community is determined partly by oxygen availability. The low oxygen conditions of oxygen minimum zones (OMZs) may select for methanotrophs that oxidize methane using inorganic nitrogen compounds (e.g., nitrate, nitrite) in place of oxygen. However, environmental evidence for methane-nitrogen linkages in OMZs remains sparse, as does our knowledge of the genomic content and metabolic capacity of organisms catalyzing OMZ methane oxidation. [...]."

Source: NCCOS

"The low oxygen conditions slow shrimp growth, leading to fewer and more expensive large shrimp. 
A NOAA-funded study led by Duke University has found that the Gulf of Mexico ' dead zone ' drives up the price of large shrimp relative to small shrimp, creating an economic impact that directly affects consumers, fishermen and seafood markets. The study, conducted in collaboration with NOAA's National Marine Fisheries Service and funded by the National Centers for Coastal Ocean Science (NCCOS) provides the first evidence linking Gulf of Mexico hypoxia to economic impacts. [...]."

Source: The Guardian

"Long treated as a bottomless resource pit, over-exploitation of the ocean, pollution and rising sea levels are having a catastrophic impact on life in the bay. [...]."

Source: Wiley Online Library
Authors: Renato Salvatteci et al.
DOI: 10.1111/gcb.13991

Abstract

"The Humboldt Current System (HCS) has the highest production of forage fish in the world, although it is highly variable and the future of the primary component, anchovy, is uncertain in the context of global warming. Paradigms based on late 20th century observations suggest that large-scale forcing controls decadal-scale fluctuations of anchovy and sardine across different boundary currents of the Pacific. We develop records of anchovy and sardine fluctuations since 1860 AD using fish scales from multiple sites containing laminated sediments and compare them with Pacific basin-scale and regional indices of ocean climate variability. [...]."

Source: Wiley Online Library
Authors: R. A. Beinart et al.
DOI: 10.1111/mec.14465

Abstract

"Symbioses between anaerobic or microaerophilic protists and prokaryotes are common in anoxic and oxygen-depleted habitats ranging from marine sediments to gastrointestinal tracts. Nevertheless, little is known about the mechanisms of metabolic interaction between partners. In these putatively syntrophic associations, consumption of fermentative end products (e.g., hydrogen) by the prokaryotic symbionts is thought to facilitate protistan anaerobic metabolism. [...]."