News

Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition

Abstract.

"The ocean is the main source of thermal inertia in the climate system. Ocean heat uptake during recent decades has been quantified using ocean temperature measurements. However, these estimates all use the same imperfect ocean dataset and share additional uncertainty due to sparse coverage, especially before 2007. Here, we provide an independent estimate by using measurements of atmospheric oxygen (O2) and carbon dioxide (CO2) – levels of which increase as the ocean warms and releases gases – as a whole ocean thermometer. [...]"

Source: Scientific Reports
Authors: L. Resplandy et al.
DOI: 10.1038/s41598-019-56490-z

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Climate Change and Harmful Algal Blooms: Insights and perspective

Abstract.

"Climate change is transforming aquatic ecosystems. Coastal waters have experienced progressive warming, acidification, and deoxygenation that will intensify this century. At the same time, there is a scientific consensus that the public health, recreation, tourism, fishery, aquaculture, and ecosystem impacts from harmful algal blooms (HABs) have all increased over the past several decades. [...]"

Source: Harmful Algae
Author: Author links open overlay panelChristopher J.Gobler
DOI: 10.1016/j.hal.2019.101731

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Greenhouse Gas Emissions From Native and Non-native Oysters

Abstract.

"Non-native species introductions are associated with a range of ecosystem changes such as habitat destruction, competition with native species, and biodiversity losses. Less well known is the role non-native species play in altering biogeochemical processes, such as the emission of greenhouse gases (GHGs). In this study we used laboratory incubations to compare seasonal (spring, summer, fall) emissions of the GHGs nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2) from native (Crassostrea virginica) and non-native (Ostrea edulis) oysters collected from a northern temperate estuary (Duxbury Bay, Massachusetts, USA). [...]"

Source: Frontiers in Environmental Science
Authors: Gretchen J. McCarthy et al.
DOI: 10.3389/fenvs.2019.00194

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Greenhouse gas cycling by the plastisphere: The sleeper issue of plastic pollution

Abstract.

"Plastic is an allochthonous material to marine ecosystems but is rapidly colonized by marine microbial communities, with an as yet unclear contribution to biogeochemical cycles. In this study, we investigated the influence of an active microbial community grown on microplastic particles (the plastisphere) on CO2 and N2O recycling and its potential role in greenhouse gas inventories and air-sea exchange. Microplastics were collected during two cruises (Cimar 21 and FIP Montes Submarinos) from the surface layer (5 m depth) from several contrasting trophic regions of the South Pacific Ocean, i.e., from a transition zone off the eutrophic coastal upwelling of Chile, to a mesotrophic transition area of oceanic seamounts and, finally, to an oligotrophic zone in the South Pacific Subtropical Gyre. [...]"

Source: Chemosphere
Authors: MarcelaCornejo-D’Ottone et al.
DOI: 10.1016/j.chemosphere.2019.125709

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Denitrification Aligns with N2 Fixation in Red Sea Corals

Abstract.

"Denitrification may potentially alleviate excess nitrogen (N) availability in coral holobionts to maintain a favourable N to phosphorous ratio in the coral tissue. However, little is known about the abundance and activity of denitrifiers in the coral holobiont. The present study used the nirS marker gene as a proxy for denitrification potential along with measurements of denitrification rates in a comparative coral taxonomic framework from the Red Sea: Acropora hemprichiiMillepora dichotoma, and Pleuractis granulosa. [...]"

Source: Scientific Reports
Authors: Arjen Tilstra et al.
DOI: 10.1038/s41598-019-55408-z

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Warming climate will impact dead zones in Chesapeake Bay

"In recent years, scientists have projected increasingly large summer dead zones in the Chesapeake Bay, areas where there is little or no oxygen for living things like crabs and fish to thrive, even as long-term efforts to reduce nutrient pollution continue. Researchers factored in local impacts of climate change to make projections of what the oxygen content of the Chesapeake Bay will look like in the future. [...]"

Source: Science Daily

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Intensified ocean deoxygenation during the end Devonian mass extinction

Abstract.

"The end‐Devonian mass extinction (~359 Ma) substantially impacted marine ecosystems and shaped the roots of modern vertebrate biodiversity. Although multiple hypotheses have been proposed, no consensus has been reached about the mechanism inducing this extinction event. In this study, I/Ca ratio of carbonate was used to unravel the changes in local oxygen content of the upper water column during this critical interval. The Devonian‐Carboniferous boundary was recorded in two shallow water carbonate sections in South China. [...]"

Source: Geochemistry, Geophysics, Geosystems
Authors: Jiangsi Liu et al.
DOI: 10.1029/2019GC008614

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Post-depositional manganese mobilization during the last glacial period in sediments of the eastern Clarion-Clipperton Zone, Pacific Ocean

Abstract.

"Numerous studies have provided compelling evidence that the Pacific Ocean has experienced substantial glacial/interglacial changes in bottom-water oxygenation associated with enhanced carbon dioxide storage in the glacial deep ocean. Under postulated low glacial bottom-water oxygen concentrations (O2bw), redox zonation, biogeochemical processes and element fluxes in the sediments must have been distinctively different during the last glacial period (LGP) compared to current well-oxygenated conditions. [...]"

Source: Earth and Planetary Science Letters
Authors: Jessica B.Volz et al.
DOI: 10.1016/j.epsl.2019.116012

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Stepwise Earth oxygenation is an inherent property of global biogeochemical cycling

Abstract.

"Oxygenation of Earth’s atmosphere and oceans occurred across three major steps during the Paleoproterozoic, Neoproterozoic, and Paleozoic eras, with each increase having profound consequences for the biosphere. Biological or tectonic revolutions have been proposed to explain each of these stepwise increases in oxygen, but the principal driver of each event remains unclear. Here we show, using a theoretical model, that the observed oxygenation steps are a simple consequence of internal feedbacks in the long-term biogeochemical cycles of carbon, oxygen, and phosphorus, and that there is no requirement for a specific stepwise external forcing to explain the course of Earth surface oxygenation. [...]"

Source: Science
Authors: Lewis J. Alcott et al.
DOI: 10.1126/science.aax6459

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Multidisciplinary Observing in the World Ocean’s Oxygen Minimum Zone Regions: From Climate to Fish — The VOICE Initiative

Abstract.

"Multidisciplinary ocean observing activities provide critical ocean information to satisfy ever-changing socioeconomic needs and require coordinated implementation. The upper oxycline (transition between high and low oxygen waters) is fundamentally important for the ecosystem structure and can be a useful proxy for multiple observing objectives connected to eastern boundary systems (EBSs) that neighbor oxygen minimum zones (OMZs). [...]"

Source: Frontiers in Marine Science
Authors: Véronique Garçon et al.
DOI: 10.3389/fmars.2019.00722

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