Seasonal nearshore ocean acidification and deoxygenation in the Southern California Bight


"The California Current System experiences seasonal ocean acidification and hypoxia (OAH) owing to wind-driven upwelling, but little is known about the intensity, frequency, and depth distribution of OAH in the shallow nearshore environment. Here we present observations of OAH and dissolved inorganic carbon and nutrient parameters based on monthly transects from March 2017 to September 2018 extending from the surf zone to the ~ 40 m depth contour in La Jolla, California. Biologically concerning OAH conditions were observed at depths as shallow as 10 m and as close as 700 m to the shoreline. [...]".


Source: Scientific Reports
Authors: Samuel A. H. Kekuewa et al. 

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Short- and long-term impacts of variable hypoxia exposures on kelp forest sea urchins


"Climate change is altering the intensity and variability of environmental stress that organisms and ecosystems experience, but effects of changing stress regimes are not well understood. We examined impacts of constant and variable sublethal hypoxia exposures on multiple biological processes in the sea urchin Strongylocentrotus purpuratus, a key grazer in California Current kelp forests, which experience high variability in physical conditions. [...]"

Source: Scientific Reports
Authors: Natalie H. N. Low & Fiorenza Micheli 
DOI: 10.1038/s41598-020-59483-5

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Response of Sea Urchin Fitness Traits to Environmental Gradients Across the Southern California Oxygen Minimum Zone


"Marine calcifiers are considered to be among the most vulnerable taxa to climate-forced environmental changes occurring on continental margins with effects hypothesized to occur on microstructural, biomechanical, and geochemical properties of carbonate structures. Natural gradients in temperature, salinity, oxygen, and pH on an upwelling margin combined with the broad depth distribution (100–1,100 m) of the pink fragile sea urchin, Strongylocentrotus (formerly Allocentrotus) fragilis, along the southern California shelf and slope provide an ideal system to evaluate potential effects of multiple climate variables on carbonate structures in situ. [...]"

Source: Frontiers in Marine Science
Authors: Kirk N. Sato et al.
DOI: 10.3389/fmars.2018.00258

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The evolving response of mesopelagic fishes to declining midwater oxygen concentrations in the southern and central California Current


"Declining oxygen concentrations in the deep ocean, particularly in areas with pronounced oxygen minimum zones (OMZs), are a growing global concern related to global climate change. Its potential impacts on marine life remain poorly understood. A previous study suggested that the abundance of a diverse suite of mesopelagic fishes off southern California was closely linked to trends in midwater oxygen concentration. [...]"

Source: ICES Journal of Marine Science
Authors: J Anthony Koslow et al.
DOI: 10.1093/icesjms/fsy154

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Reconstructing Aragonite Saturation State Based on an Empirical Relationship for Northern California


"Ocean acidification is a global phenomenon with highly regional spatial and temporal patterns. In order to address the challenges of future ocean acidification at a regional scale, it is necessary to increase the resolution of spatial and temporal monitoring of the inorganic carbon system beyond what is currently available. One approach is to develop empirical regional models that enable aragonite saturation state to be estimated from existing hydrographic measurements, for which greater spatial coverage and longer time series exist in addition to higher spatial and temporal resolution. [...]"

Source: Estuaries and Coasts
Authors: Catherine V. Davis et al.
DOI: 10.1007/s12237-018-0372-0

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Persistent spatial structuring of coastal ocean acidification in the California Current System


"The near-term progression of ocean acidification (OA) is projected to bring about sharp changes in the chemistry of coastal upwelling ecosystems. The distribution of OA exposure across these early-impact systems, however, is highly uncertain and limits our understanding of whether and how spatial management actions can be deployed to ameliorate future impacts. Through a novel coastal OA observing network, we have uncovered a remarkably persistent spatial mosaic in the penetration of acidified waters into ecologically-important nearshore habitats across 1,000 km of the California Current Large Marine Ecosystem.  [...]"

Source: Scientific Reports
Authors: F. Chan et al.
DOI: 10.1038/s41598-017-02777-y

Full article


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