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Drivers and Potential Consequences of Observed Extreme Hypoxia Along the Canadian Pacific Continental Shelf

Abstract. 

"Bottom waters of the northeast Pacific continental shelf naturally experience localized hypoxic conditions, with significant influences on food webs and biogeochemical cycling. In August 2021, extreme hypoxia was detected from several measurement platforms along the southern British Columbia continental shelf, with oxygen concentration <60 μmol kg−1, and a difference from the seasonal climatology of more than 2 standard deviations. Early and intense remote upwelling and local density shifts were associated with an anomalously strong spring phytoplankton bloom, which likely stimulated localized respiration of subsurface organic matter. [...]".

 

Source: Wiley Online Library 
Authors: Ana C. Franco et al.
DOI: https://doi.org/10.1029/2022GL101857

Read the full article here.


Impact of warming and deoxygenation on the habitat distribution of Pacific halibut in the Northeast Pacific

Abstract. 

"Ocean warming and deoxygenation are already modifying the habitats of many aerobic organisms. Benthic habitat in the Northeast Pacific is sensitive to deoxygenation, as low oxygen concentrations occur naturally in continental shelf bottom waters. Here, we examine the potential impacts of deoxygenation and ocean warming on the habitat distribution of Pacific halibut (Hippoglossus stenolepis), one of the most commercially important groundfish in North America. [...]".

 

Source: Wiley Online Library  
Authors: Ana C. Franco et al.
DOI: https://doi.org/10.1111/fog.12610

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Rain-fed streams dilute inorganic nutrients but subsidise organic-matter-associated nutrients in coastal waters of the northeast Pacific Ocean

Abstract.

"In coastal regions, rivers and streams may be important sources of nutrients limiting to primary production in marine waters; however, sampling is still rarely conducted across the land-to-ocean aquatic continuum, precluding conclusions from being drawn about connectivity between freshwater and marine systems. Here we use a more-than-4-year dataset (2014–2018) of nutrients (nitrogen, phosphorus, silica, iron) and dissolved organic carbon spanning streams draining coastal watersheds and nearshore marine surface waters along the Central Coast of British Columbia, Canada, at the heart of the North Pacific coastal temperate[...]"

 

Source: Biogeosciences
Authors: Kyra A. St. Pierre et al.
DOI: https://doi.org/10.5194/bg-18-3029-2021

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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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Oregon Shelf Hypoxia Modeling

Abstract.

"Bottom hypoxia on the shelf in the Northeast Pacific is caused by different processes than coastal hypoxia related to riverine inputs. Hypoxia off the coast of Oregon is a naturally occurring process as opposed to the anthropogenically forced hypoxia found in many coastal environments (e.g., Gulf of Mexico shelf, Chesapeake Bay). Off Oregon, bottom hypoxia occurs in summers that have large upwelling-driven near-bottom transport of high nitrate, low dissolved oxygen (DO) waters onto the shelf. The combination of low DO and high nitrate provides initially low (but not hypoxic) DO conditions near the bottom, and nitrate fertilization of shelf surface waters, leading to substantial phytoplankton production. [...]"

Source: Modeling Coastal Hypoxia (pp 215-238)
Authors: Andrey O. Koch, Yvette H. Spitz, Harold P. Batchelder
DOI: 10.1007/978-3-319-54571-4_9

Full article


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