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Benthic fluxes of oxygen and heat from a seasonally hypoxic region of Saanich Inlet fjord observed by eddy covariance

Abstract.

"Benthic habitats within fjords are predominantly insulated from the high energy physical dynamics of open coastlines. As a result, fjords may have atypical mass and heat transfer rates at the seafloor. This study presents aquatic eddy covariance (EC) measurements made continuously from late May 2013 through December 2013, in Saanich Inlet fjord, British Columbia, to assess areal-averaged benthic fluxes of dissolved oxygen and heat, and their relationships to bottom boundary layer dynamics and water properties. The measurements were achieved by the connection of a system of underwater EC sensors to Ocean Network Canada's Victoria Experimental Network Under the Sea (VENUS) observatory that has a primary seafloor node[...]"

 

Source: Science Direct
Authors: Clare E. Reimers et al.
DOI: https://doi.org/10.1016/j.ecss.2020.106815

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Recovery from multi-millennial natural costal hypoxia in the Stockholm Archipelago, Baltic Sea, terminated by modern human activity

Abstract.

"Enhanced nutrient input and warming have led to the development of low oxygen (hypoxia) in coastal waters globally. For many coastal areas, insight into redox conditions prior to human impact is lacking. Here, we reconstructed bottom water redox conditions and sea surface temperatures (SSTs) for the coastal Stockholm Archipelago over the past 3000 yr. Elevated sedimentary concentrations of molybdenum indicate (seasonal) hypoxia between 1000 b.c.e. and 1500 c.e. Biomarker[...]"

 

Source: ASsociation for the Sciences of Limnology and Oceanography
Authors: Niels A. G. M. van Helmond et al.
DOI: https://doi.org/10.1002/lno.11575

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Benthic fluxes of oxygen and nutrients under the influence of macrobenthic fauna on the periphery of the intermittently hypoxic zone in the Baltic Sea

Abstract.

"Understanding the role of benthic organisms in marine sediments is becoming increasingly important with the growing problem of eutrophication of marine ecosystems around the world, including the Baltic Sea. Therefore, we have conducted a series of incubation experiments on sediment cores collected from sites characterized by varying oxygen conditions and measured the influx (uptake by sediment) of oxygen as well as the sediment–water exchange of phosphate, ammonia and silicate.[...]"

 

Source: Science Direct
Authors: Halina Kendzierska et al.
Doi: https://doi.org/10.1016/j.jembe.2020.151439

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Impacts of climate change on dissolved oxygen concentration relevant to the costal and marine environment around the UK

Abstract.

"The decline in dissolved oxygen and onset of oxygen deficiency and hypoxia are naturally occurring phenomenon in aquatic environments, typically occurring on seasonal timescales. Over decadal timescales, there has been a measurable decline in dissolved oxygen concentrations in the global ocean due to warming caused by anthropogenic activity. Approximately 15% of the global decline in oxygen has been attributed to reduced solubility in response to ocean warming, with the remaining 85% due to intensified stratification. The relative contribution of these factors in coastal and shelf-sea waters is currently unknown. In UK waters, sustained observations in the North[...]"

 

Source: MCCIP Science Review
Authors: Mahaffey, C et al.
DOI: https://doi.org/10.14465/2020.arc02.oxy

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Metabolic trait diversity shapes marine biogeography

Abstract.

"Climate and physiology shape biogeography, yet the range limits of species can rarely be ascribed to the quantitative traits of organisms1,2,3. Here we evaluate whether the geographical range boundaries of species coincide with ecophysiological limits to acquisition of aerobic energy4 for a global cross-section of the biodiversity of marine animals. We observe a tight correlation between the metabolic rate and the efficacy of oxygen supply, and between the temperature sensitivities[...]"

 

Source: Nature
Authors: Curtis Deutsch et al.
DOI: https://doi.org/10.1038/s41586-020-2721-

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Geoengineered Ocean Vertical Water Exchange Can Accelerate Global Deoxygenation

Abstract.

"Ocean deoxygenation is a threat to marine ecosystems. We evaluated the potential of two ocean intervention technologies, that is, “artificial downwelling (AD)” and “artificial upwelling (AU),” for remedying the expansion of Oxygen Deficient Zones (ODZs). The model‐based assessment simulated AD and AU implementations for 80 years along the eastern Pacific ODZ.[...]"

Source: Advancing Earth And Space Science 
Authors: Ellias Yuming Feng et al.
DOI: https://doi.org/10.1029/2020GL088263

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Slightly smaller-than-average 2020 ‘dead zone’ predicted for Chesapeake Bay

"Researchers from the University of Michigan, the Chesapeake Bay Program and the University of Maryland Center for Environmental Science are forecasting a slightly smaller-than-average Chesapeake Bay “dead zone” this year, due to reduced rainfall and less nutrient-rich runoff flowing into the bay from the watershed this spring. [...]"

Source: University of Michigan

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Quantifying the contributions of riverine vs. oceanic nitrogen to hypoxia in the East China Sea

Abstract.

"In the East China Sea, hypoxia (oxygen ≤ 62.5 mmol m−3) is frequently observed off the Changjiang (or Yangtze River) estuary covering up to about 15 000 km2. The Changjiang is a major contributor to hypoxia formation because it discharges large amounts of freshwater and nutrients into the region. However, modeling and observational studies have suggested that intrusions of nutrient-rich oceanic water from the Kuroshio Current also contribute to hypoxia formation.  [...]"

Source: Biogeosciences
Authors: Fabian Große et al.
DOI: 10.5194/bg-17-2701-2020

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Short-term effects of hypoxia are more important than effects of ocean acidification on grazing interactions with juvenile giant kelp

Abstract.

"Species interactions are crucial for the persistence of ecosystems. Within vegetated habitats, early life stages of plants and algae must survive factors such as grazing to recover from disturbances. However, grazing impacts on early stages, especially under the context of a rapidly changing climate, are largely unknown. [...]"

Source: Scientific Reports
Authors: Crystal A. Ng & Fiorenza Micheli 
DOI: 10.1038/s41598-020-62294-3

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Effects of spatial variability on the exposure of fish to hypoxia: a modeling analysis for the Gulf of Mexico

Abstract.

"The hypoxic zone in the northern Gulf of Mexico varies spatially (area, location) and temporally (onset, duration) on multiple scales. Exposure to hypoxic dissolved oxygen (DO) concentrations (< 2 mg L−1) is often lethal and exposure to 2 to 4 mg L−1 often causes the sublethal effects of decreased growth and fecundity on individuals of many fish species. We simulated the movement of individual fish within a high-resolution 3-D coupled hydrodynamic-water quality model (FVCOM-WASP) configured for the northern Gulf of Mexico to examine how spatial variability in DO concentrations would affect fish exposure to hypoxic and sublethal DO concentrations. [...]"

Source: Biogeosciences
Authors: Elizabeth D. LaBone et al.
DOI: 10.5194/bg-2020-51

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