News

Persistent eutrophication and hypoxia in the coastal ocean

Abstract. 

"Coastal eutrophication and hypoxia remain a persistent environmental crisis despite the great efforts to reduce nutrient loading and mitigate associated environmental damages. Symptoms of this crisis have appeared to spread rapidly, reaching developing countries in Asia with emergences in Southern America and Africa. The pace of changes and the underlying drivers remain not so clear. To address the gap, we review the up-to-date status and mechanisms of eutrophication and hypoxia in global coastal oceans, upon which we examine the trajectories of changes over the 40 years or longer in six model coastal systems [...]".

 

Source: Cambridge University Press
Authors: Minhan Dai et al. 
DOI: https://doi.org/10.1017/cft.2023.7

Read the full article here.


A molecular perspective on the invasibility of the southern ocean benthos: The impact of hypoxia and temperature on gene expression

Abstract. 

"When an organism makes a long-distance transition to a new habitat, the associated environmental change is often marked and requires physiological plasticity of larvae, juveniles, or other migrant stages. Exposing shallow-water marine bivalves (Aequiyoldia cf. eightsii) from southern South America (SSA) and the West Antarctic Peninsula (WAP) to changes in temperature and oxygen availability, we investigated changes in gene expression in a simulated colonization experiment of the shores of a new continent after crossing of the Drake Passage, and in a warming scenario in the WAP. [...]".

 

Source: Frontiers
Authors: Mariano Martínez et al.
DOI: https://doi.org/10.3389/fphys.2023.1083240

Read the full article here.


Early detection of anthropogenic climate change signals in the ocean interior

Abstract. 

"Robust detection of anthropogenic climate change is crucial to: (i) improve our understanding of Earth system responses to external forcing, (ii) reduce uncertainty in future climate projections, and (iii) develop efficient mitigation and adaptation plans. Here, we use Earth system model projections to establish the detection timescales of anthropogenic signals in the global ocean through analyzing temperature, salinity, oxygen, and pH evolution from surface to 2000 m depths. For most variables, anthropogenic changes emerge earlier in the interior ocean than at the surface, due to the lower background variability at depth. [...]".

 

Source: Nature 
Authors: Jerry F. Tjiputra et al.
DOI: https://doi.org/10.1038/s41598-023-30159-0

Read the full article here.


Aquatic Productivity under Multiple Stressors

Abstract. 

"Aquatic ecosystems are responsible for about 50% of global productivity. They mitigate climate change by taking up a substantial fraction of anthropogenically emitted CO2 and sink part of it into the deep ocean. Productivity is controlled by a number of environmental factors, such as water temperature, ocean acidification, nutrient availability, deoxygenation and exposure to solar UV radiation. Recent studies have revealed that these factors may interact to yield additive, synergistic or antagonistic effects. While ocean warming and deoxygenation are supposed to affect mitochondrial respiration oppositely [...]".

 

Source: MDPI
Authors: Donat-P. Häder & Kunshan Gao
DOI: https://doi.org/10.3390/w15040817

Read the full article here.


Climate Change Impacts on Dissolved Oxygen Concentration in Marine and Coastal Waters around the UK and Ireland

Abstract. 

"What is already happening

  • Since the 1960s, the global oceanic oxygen content has declined by more than 2%.
  • Sustained observations in the North Sea reveal the recent onset of oxygen deficiency in late summer, partly due to ocean warming. The intensity and extent of oxygen deficiency has also increased over time. [...]".

 

Source: Marine Climate Change Impacts Partnership  
Authors: Claire Mahaffey et al.
DOI: 10.14465/2023.reu07.oxy

Read the full article here.


Arctic deep-water anoxia and its potential role for ocean carbon sink during glacial periods

Abstract. 

"Deep water freshening beneath pan-Arctic ice shelves has recently been proposed based on the absence of excess thorium in glacial Arctic sediments. This profound proposal requires scrutiny of Arctic paleohydrology during past glacial periods. Here, we present structural and geochemical results of inorganic authigenic carbonates in deep-sea glacimarine sediments from the Mendeleev Ridge, western Arctic Ocean over the last 76 kyr. Our results suggest that Polar Deep Water in the western Arctic became brackish and anoxic during stadial periods. We argue that sediment-laden hyperpycnal meltwater discharged from paleo-ice sheets filled much of the water column [...]".

 

Source: Nature 
Authors: Kwangchul Jang et al.
DOI: https://doi.org/10.1038/s43247-023-00708-6

Read the full article here.


Global ocean redox changes before and during the Toarcian Oceanic Anoxic Event

Abstract. 

"Mesozoic oceanic anoxic events are recognized as widespread deposits of marine organic-rich mudrocks temporally associated with mass extinctions and large igneous province emplacement. The Toarcian Oceanic Anoxic Event is one example during which expanded ocean anoxia is hypothesized in response to environmental perturbations associated with emplacement of the Karoo–Ferrar igneous province. However, the global extent of total seafloor anoxia and the relative extent of euxinic (anoxic and sulfide-rich) and non-euxinic anoxic conditions during the Toarcian Oceanic Anoxic Event are poorly constrained. [...]".

 

Source: Nature
Authors: Alexandra Kunert & Brian Kendall
DOI: https://doi.org/10.1038/s41467-023-36516-x

Read the full article here.


Physiological and gene expression responses of the mussel Mytilus galloprovincialis to low pH and low dissolved oxygen

Abstract. 

"The prevalence and frequency of hypoxia events have increased worldwide over the past decade as a consequence of global climate change and coastal biological oxygen depletions. On the other hand, anthropogenic emissions of CO2 and consequent accumulation in the sea surface result in a perturbation of the seawater carbonate system, including a decrease in pH, known as ocean acidification. While the effect of decreases in pH and dissolved oxygen (DO) concentration is better understood, their combined effects are still poorly resolved. [...]". 

 

Source: Science Direct 
Authors: Murat Belivermiş et al.
DOI: https://doi.org/10.1016/j.marpolbul.2023.114602

Read the full article here.


Editorial: Regional coastal deoxygenation and related ecological and biogeochemical modifications in a warming climate

Abstract. 

"Coastal ecosystems play tremendous roles in socio-economic development, but their functions are degrading due to human activities. One of the most alarming degradations is coastal deoxygenation, driven primarily by the over-enrichment of anthropogenic nutrients and organic matter (eutrophication) in the coastal waters. The coastal deoxygenation has led to the worldwide spread of hypoxic zones (where dissolved oxygen concentration is less than 2 mg/L), with the number of reported hypoxic sites increasing from 45 in the 1960s to around 700 nowadays. Besides being perturbed by human activities locally, coastal waters respond more rapidly than [...]".

 

Source: Frontiers 
Authors: Wenxia Zhang et al.
DOI: https://doi.org/10.3389/fmars.2023.1146877

Read the full article here.


Warming, Acidification and Deoxygenation of the Ocean

Abstract. 

"The ocean plays an essential role in regulating Earth’s climate. The ocean provides many services, but two crucial ones are its ability to take up heat and carbon dioxide (CO2) from the atmosphere and cycle both around the world in its vast currents, as well as store them away long term. The ocean is changing rapidly and often unnoticed by the general public. However, as the effects of climate change become more prevalent on the ocean, we will start to see a direct impact on human society. This chapter discusses three main climate change effects on the ocean: ocean warming, acidification, and loss of oxygen. [...]".

 

Source: Springer Nature
Authors: Helen S. Findlay
DOI: https://doi.org/10.1007/978-3-031-10812-9_2

Read the full article here.


Effects of different oxygen regimes on ecological performance and bioenergetics of a coastal marine bioturbator, the soft shell clam Mya arenaria

Abstract. 

"Benthic species are exposed to oxygen fluctuations that can affect their performance and survival. Physiological effects and ecological consequences of fluctuating oxygen are not well understood in marine bioturbators such as the soft-shell clam Mya arenaria. We explored the effects of different oxygen regimes (21 days of exposure to constant hypoxia (~4.1 kPa PO2), cyclic hypoxia (~2.1–~10.4 kPa PO2) or normoxia (~21 kPa PO2)) on energy metabolism, oxidative stress and ecological behaviors (bioirrigation and bioturbation) of M. arenaria. Constant hypoxia and post-hypoxic recovery in cyclic hypoxia led to oxidative injury of proteins and [...]".

 

Source: Science Direct 
Authors: Natascha Ouillon et al.
DOI: https://doi.org/10.1016/j.scitotenv.2022.160459

Read the full article here.


Frontiers in Marine Science special issue on ocean deoxygenation: Call for papers

Call for paper manuscripts

We would like to draw your attention to a call for paper manuscripts for a special issue on "Constraining Uncertainties in Hindcasts and Future Projections of Marine Deoxygenation" in Frontiers in Marine Science.

The paper manuscript submission deadline is 7 April 2023.

Further informationhttps://www.frontiersin.org/research-topics/24190/constraining-uncertainties-in-hindcasts-and-future-projections-of-marine-deoxygenation


ASLO Aquatic Sciences Meeting 2023: Registration and Abstract Submission

Call for Abstract and Early Registration closing on 23 February 2023

ASLO Aquatic Sciences Meeting 2023: 4–9 June 2023 in Palma de Mallorca, Spain

Resilience and Recovery in Aquatic Systems

Sessions on ocean oxygen, deoxygenation, anoxia, and hypoxia:

  • SS015 Deoxygenation in the Past, Present and Future Ocean
  • SS050 Disentangling Complex Long-Term pH and O2 Trends in Coastal and Estuarine Systems From Global and Regional Drivers
  • SS107 Oxic-Anoxic Interfaces: Pathways, Dynamics and Exchanges

For further information, please visit the event's homepagesessions list, registration information, and abstract preparation guide


Euxinia and hydrographic restriction in the Tethys Ocean: Reassessing global oceanic anoxia during the early Toarcian

Abstract. 

"Despite carbon-cycle perturbations at a global scale during the early Toarcian, the extent of anoxia during the ∼182-Ma Toarcian Oceanic Anoxic Event (T-OAE) remains in debate. A common factor in the development of oceanic anoxia is watermass restriction, which is thought to have been important in the NW European Seaway, but whose influence elsewhere is relatively unstudied. Here, we analyze Mo/TOC (a proxy for watermass restriction) and redox proxies (e.g., Corg/P) in two sections of the Asturian Basin (northern Iberian Paleomargin), and we integrate these results with data from a suite of global Toarcian sections in order to reassess [...]".

 

Source: Science Direct 
Authors: Javier Fernández-Martínez et al.
DOI: https://doi.org/10.1016/j.gloplacha.2022.104026

Read the full article here.


Marine osmium‑uranium‑sulfur isotope evidence for the interaction of volcanism and ocean anoxia during the Middle Pleistocene

Abstract.

"Before the Quaternary, the Earth experienced a series of environmental perturbations. The causal links between large volcanic events, extreme climatic change, and ocean anoxia have been examined in the context of these perturbations. However, to date, the correlation between oceanic anoxia and large volcanic activity in the Pleistocene remains poorly constrained. Identifying the physical processes that can control changes to the marine osmium, uranium, and sulfur isotope ratios is critical to understanding how volcanic activity, climate changes, and ocean anoxia have coevolved throughout the Quaternary. [...]".

 

Source: Science Direct 
Authors: Wenlong Pei et al. 
DOI: https://doi.org/10.1016/j.palaeo.2022.111360

Read the full article here.


The effects of seawater thermodynamic parameters on the oxygen minimum zone (OMZ) in the tropical western Pacific Ocean

Abstract.

"The continuous expansion of the oxygen minimum zone (OMZ) is a microcosm of marine hypoxia problem. Based on a survey in M4 seamount area of Tropical Western Pacific Ocean, the effects of thermodynamic parameters on OMZ were discussed. The study showed thermodynamic parameters mainly affect the upper oxycline of OMZ. The increase in temperature aggravates seawater stratification, which not only shallows oxycline but also increases the strength of DO stratification, promoting the expansion of OMZ. [...]".

 

Source: Science Direct 
Authors: Jun Ma et al. 
DOI: https://doi.org/10.1016/j.marpolbul.2023.114579

Read the full article here.


Temporal and spatial variability in hydrography and dissolved oxygen along southwest Nova Scotia using glider observations

Abstract. 

"Dissolved oxygen (DO) in the global ocean is on the decline, resulting in the degradation of coastal habitats. As aquaculture production occurs in these regions, proper understanding of coastal DO dynamics is important for improved farm management (e.g. site selection). The main objective of this study was to quantify along-shore and cross-shore variability in DO dynamics, as well as onshore advection of offshore waters to the bays that could contain aquaculture farms. [...]".

 

Source: Science Direct 
Authors: Meredith Burke et al.
DOI: https://doi.org/10.1016/j.csr.2022.104908

Read the full article here.


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