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Dissolved oxygen and pH criteria leave fisheries at risk

Abstract.

"Changes in human population centers and agricultural fertilizer use have accelerated delivery rates of nitrogen and phosphorus to coastal waters, often stimulating rapid accumulations of primary production (1). Whereas resulting eutrophication processes are of less environmental relevance in well-mixed, ocean ecosystems, when they occur in warm, stratified, and/or poorly mixed waters, they can result in hypoxia [depletion of dissolved oxygen (DO)] and acidification (decrease in pH), both of which individually can have adverse effects on aquatic life, affecting a suite of physiological processes and increasing mortality rates (23). [...]"

Source: Science
Authors: Stephen J. Tomasetti, Christopher J. Gobler
DOI: 10.1126/science.aba4896

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Physical preconditioning of oxygen depletion in shelf seas

Abstract.

"The global ocean dissolved oxygen (DO) inventory is decreasing and the areal extent of DO deficiency is increasing. In the shelf sea BML, net DO removal can occur as a result of restricted ventilation due to seasonal thermal stratification, oxygen consumption via pelagic and benthic respiration of organic matter, and nitrification. DO decline is becoming evident in several shelf seas, with recent model studies estimating that large regions of the Northwest European continental shelf seas (325,000 to 400,000 km2) have the potential to become seasonally deficient in DO in late summer. It is therefore of vital importance that DO is monitored accurately and effectively in shelf seas. [...]"

Source: EGU General Assembly 2020
Authors: Charlotte Williams et al.
DOI: 10.5194/egusphere-egu2020-20219

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Effects of hypoxia on the behavior and physiology of kelp forest fishes

Abstract.

"Forecasts from climate models and oceanographic observations indicate increasing deoxygenation in the global oceans and an elevated frequency and intensity of hypoxic events in the coastal zone, which have the potential to affect marine biodiversity and fisheries. Exposure to low dissolved oxygen (DO) conditions may have deleterious effects on early life stages in fishes.  [...]"

Source: Global Change Biology
Authors: Evan G. Mattiasen et al.
DOI: 10.1111/gcb.15076

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Global certified-reference-material- or reference-material-scaled nutrient gridded dataset GND13

Abstract.

"A global nutrient gridded dataset that might be the basis for studies of more accurate spatial distributions of nutrients in the global ocean was created and named GND13. During 30 cruises, reference materials of nutrients in seawater or their equivalents were used at all stations, and high-precision measurements were made. The precision of the nutrient analyses was better than 0.2 %. Data were collected from the hydrographic cruises in the JASMTEC R/V Mirai cruises, JMA cruise, CARINA, PACIFICA, and WGHC datasets from which nutrient data were available. [...]"

Source: Earth System Science Data
Authors: Michio Aoyama
DOI: 10.5194/essd-12-487-2020

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Application of geoacoustic inference to assess the diurnal effects of photosynthetic activity in a seagrass meadow

Abstract.

"Seagrasses provide a multitude of ecosystem services: they alter water flow, cycle nutrients, stabilize sediments, support the food web structure, and provide a critical habitat for many animals. However, due to threats to seagrass meadows and their associated ecosystems, these habitats are declining globally. Acoustical methods can be a powerful remote sensing tool to efficiently monitor seagrass meadows, alleviating the problem of space and time aliasing associated with traditional spot measurements. [...]"

Source: Earth and Space Science Open Archive
Authors: Megan Ballard et al.
DOI: 10.1002/essoar.10502265.1

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Observed spatiotemporal variation of three-dimensional structure and heat/salt transport of anticyclonic mesoscale eddy in Northwest Pacific

Abstract.

"As in-situ observations are sparse, targeted observations of a specific mesoscale eddy are rare. Therefore, it is difficult to study the three-dimensional structure of moving mesoscale eddies. From April to September 2014, an anticyclonic eddy located at 135°E–155°E, 26°N–42°N was observed using 17 rapid-sampling Argo floats, and the spatiotemporal variations in the three-dimensional structure were studied. [...]"

Source: Journal of Oceanology and Limnology
Authors: Jun Dai et al.
DOI: 10.1007/s00343-019-9148-z

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Variability of dissolved oxygen in the Arabian Sea Oxygen Minimum Zone and its driving mechanisms

Abstract.

"The Arabian Sea hosts one of the most intense, perennial Oxygen Minimum Zones (OMZ) in the world ocean. Observations along a meridional transect at 68°E extending from 8 to 21°N showed large seasonal as well as interannual changes in the dissolved oxygen and nitrite concentrations. Unlike previous studies that used observations from the periphery of the OMZ, our observations are from its core and also allow us demarcating the southern extent of the OMZ. [...]"

Source: Journal of Marine Systems
Authors: Damodar M.Shenoy et al.
DOI: 10.1016/j.jmarsys.2020.103310 

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Diel and tidal pCO2 × O2 fluctuations provide physiological refuge to early life stages of a coastal forage fish

Abstract.

"Coastal ecosystems experience substantial natural fluctuations in pCO2 and dissolved oxygen (DO) conditions on diel, tidal, seasonal and interannual timescales. Rising carbon dioxide emissions and anthropogenic nutrient input are expected to increase these pCO2 and DO cycles in severity and duration of acidification and hypoxia. [...]"

Source: Scientific Reports
Authors: Emma L. Cross et al.
DOI: 10.1038/s41598-019-53930-8

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Large projected decline in dissolved oxygen in a eutrophic estuary due to climate change

Abstract.

"Climate change is known to cause deoxygenation in the open ocean, but its effects on eutrophic and seasonally hypoxic estuaries and coastal oceans are less clear. Using Chesapeake Bay as a study site, we conducted climate downscaling projections for dissolved oxygen and found that the hypoxic and anoxic volumes would increase by 10‐30% between the late 20th and mid‐21st century. [...]"

Source: JGR Oceans
Authors: Wenfei Ni et al. 
DOI: 10.1029/2019JC015274

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Spatiotemporal changes of ocean carbon species in the western North Pacific using parameterization technique

Abstract.

"We constructed parameterizations for the estimation of dissolved inorganic carbon (DIC) and pH in the western North Pacific, including Japanese coastal regions. Parameterizations, determined as a function of potential temperature (θ) and dissolved oxygen (DO), provided strong correlations with direct measurements for DIC [the coefficient of determination (R2) = 0.99; the root mean square error (RMSE) = 8.49 µmol kg−1] and pH (R2 = 0.98, RMSE = 0.030). [...]"

Source: Journal of Oceanography
Authors: Yutaka W. Watanabe et al.
DOI: 10.1007/s10872-019-00532-7

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