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: Scientific Data
Authors: Steven J. Hallam, Mónica Torres-Beltrán & Alyse K. Hawley
DOI: 10.1038/sdata.2017.158

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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.

"The eight-year interdisciplinary study, which began in 2009 and involved more than 250 scientist in the German research network on ocean acidification BIOACID (Biological Impacts of Ocean Acidification), investigated how different marine species respond to ocean acidification – a change in the ocean chemistry that occurs when carbon dioxide (CO2) from the atmosphere dissolves in seawater.

In addition to ocean acidification, the study, Exploring Ocean Change: Biological Impacts of Ocean Acidification, also examined the cascading effect of other stressors such as ocean warming, deoxygenation, overfishing and eutrophication – the increased concentration of nutrients in estuaries and coastal waters that causes harmful algal blooms, ocean dead zones and fish kills. [...]"

Source: The Independent Barents Observer

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"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: EurekAlert

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Abstract.

"Every 2–7 years, El Niño 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 1958–2008 period. Model evaluation using satellite and in situ observations shows that the model reproduces the surface and subsurface interannual physical and biogeochemical variability. [...]"

Source: Journal of Geophysical Research: Oceans
Authors: D. Espinoza-Morriberón
DOI: 10.1002/2016JC012439

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Abstract.

"The upwelling system off central Chile (36.5° S) 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 (30–50 m 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: Biogeosciences
Authors: Alexander Galán et al.
DOI: 10.5194/bg-14-4795-2017

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Abstract.

"Abstract. The Puyuhuapi Fjord is an atypical fjord, with two mouths, located in northern Patagonia (44.7° S). One mouth lies to the south, close to the Pacific Ocean, whilst the second connects with the Jacaf Channel to the north where a shallow sill inhibits deep water ventilation contributing to the hypoxic conditions below ~ 100 m depth. Acoustic Doppler Current Profiler moorings, scientific echo sounder transects, and in-situ abundance measurements were used to study zooplankton assemblages and migration patterns along Puyuhuapi Fjord and Jacaf Channel. […]"

Source: Ocean Science (in review)
Authors: Iván Pérez-Santos et al.
DOI: 10.5194/os-2017-89

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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: Geophysical Research Letters
Authors: Muchamad Al Azhar, Zouhair Lachkar, Marina Lévy, Shafer Smith
DOI: 10.1002/2017GL075157

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"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’s crust down two centimeters. [...]

What oceanographers do know about the interface of freshwater and ocean comes from studying rivers that naturally empty into the sea. The key is density. Because freshwater lacks dissolved salt, it is less dense and floats atop seawater. It becomes a barrier between the air and the ocean water, which can have nasty consequences. “The freshwater sitting on the salty water cuts off the oxygen from the atmosphere getting into the ocean, and then you get the dead zone,” says Steve DiMarco [...]"

Source: The Atlantic

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Abstract.

"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–specific δ¹⁵N values derived from common dolphins, an apex pelagic predator, and using two FCL proxies.  [...]"

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

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

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"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.

Researchers from the University of Adelaide and the University of Hong Kong showed that a higher concentration of carbon dioxide in the oceans, which reacts to turn seawater more acidic, favors common fish species, allowing them to double their populations. But that might also mean the downfall of rarer, subordinate competitors, leading to biodiversity loss and a total restructuring of fish communities, with numerous ecological impacts. [...]"

Source: Mongabay

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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: Scientific Reports
Authors: Myrina Boulais et al.
DOI: 10.1038/s41598-017-13480-3

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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: Biogeosciences
Authors: Xianbiao Lin et al.
DOI: 10.1002/2017JG004036

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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: Scientific Reports
Authors: Stefano Bonaglia et al.
DOI: 10.1038/s41598-017-13263-w

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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° N to 38° S). [...]"

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

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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: European Journal of Phycology 
Author: John A. Raven
DOI: 10.1080/09670262.2017.1362593

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In June, federal scientists predicted a bigger-than-average oxygen-deprived dead zone in the Chesapeake Bay this summer, and it turns out they were right.

Researchers with the Virginia Institute of Marine Science who study bay hypoxia announced Monday that the total amount of dead zones this summer was the worst since 2014, and a 10 percent increase over last year.

Source: Daily Press

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"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: Mind Guild

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

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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: Global Biogeochemical Cycles
Authors: Daoxun Sun, Takamitsu Ito, Annalisa Bracco
DOI: 10.1002/2017GB005716

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"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: Phys.org

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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 (2.6–11.0% 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: Aquatic Toxicology
Authors: YangfanZhang et al.
DOI: 10.1016/j.aquatox.2017.07.020

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"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: NewsDeeply: Oceans Deeply

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