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Pteropods are excellent recorders of surface temperature and carbonate ion concentration

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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The possible roles of algae in restricting the increase in atmospheric CO2 and global temperature

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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Chesapeake Bay dead zone this summer worst since 2014

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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Low Oxygen Dead Zones in the Pacific Ocean are Growing

"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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Oxic-anoxic regime shifts mediated by feedbacks between biogeochemical processes and microbial community dynamics

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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Oceanic uptake of oxygen during deep convection events through diffusive and bubble mediated gas exchange

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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European sea bass show chronic impairment after exposure to crude oil

"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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Exposure of European sea bass [...] to chemically dispersed oil has a chronic residual effect on hypoxia tolerance but not aerobic sc

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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What Scientists Are Learning About the Impact of an Acidifying Ocean

"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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Ecophysiological limits to aerobic metabolism in hypoxia determine epibenthic distributions and energy sequestration in the northeast Pacific ocean

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: Limonology and Oceanography
Authors: Jackson W. F. Chu, Katie S. P. Gale
DOI: 10.1002/lno.10370

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