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Effects of Experimental Ocean Acidification on the Larval Morphology and Metabolism of a Temperate Sparid, Chrysoblephus laticeps

Abstract.

"Ocean acidification is predicted to have widespread impacts on marine species. The early life stages of fishes, being particularly sensitive to environmental deviations, represent a critical bottleneck to recruitment. We investigated the effects of ocean acidification (∆pH = −0.4) on the oxygen consumption and morphometry during the early ontogeny of a commercially important seabream, Chrysoblephus laticeps, up until flexion. Hatchlings appeared to be tolerant to hypercapnic conditions, exhibiting no difference in oxygen consumption or morphometry between treatments, although the yolk reserves were marginally reduced in the low-pH treatment. The preflexion stages appeared[...]"

 

Source: MDPI
Authors: Cuen Muller et al.
DOI: https://doi.org/10.3390/oceans2010002

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Os isotopic composition of western Aleutian adakites: Implications for the Re/Os of oceanic crust processed through hot subduction zones

Abstract.

"Constraining the behaviour of Re and Os during eclogite melting is required to understand the Re and Os budget and 187Os/188Os of recycled slabs produced at warm subduction zones. It is particularly relevant to early Earth history, a period during which slab melting could have prevailed over dehydration due to higher mantle temperatures. There are however currently few constraints on Re and Os mobility during slab melting. Accordingly, we measured Os, Re and 187Os/188Os in primitive submarine lavas (Mg# ˃ 0.6) from the western Aleutian Arc. These include strongly adakitic rocks shown[...]"

 

Source: Science Direct
Authors: Rachel Bezard et al.
DOI: https://doi.org/10.1016/j.gca.2020.10.009

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Limited iodate reduction in shipboard seawater incubations from the Eastern Tropical North Pacific oxygen deficient zone

Abstract.

"The relative abundance of the inorganic iodine species, iodide and iodate, are applied to characterize both modern and ancient marine oxygen deficient zones (ODZs). However, the rates and mechanisms responsible for in situ iodine redox transformations are poorly characterized, rendering iodine-based redox reconstructions uncertain. Here, we provide constraints on the rates and mechanisms of iodate reduction in the Eastern Tropical North Pacific (ETNP) offshore ODZ using a shipboard tracer–incubation method. Observations of iodate reduction from incubations[...]"

 

Source: Science Direct
Authors: D.S. Hardisty et al.
DOI: https://doi.org/10.1016/j.epsl.2020.116676

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Sensitivity of 21st-century projected ocean new production changes to idealized biogeochemical model structure

Abstract.

"While there is agreement that global warming over the 21st century is likely to influence the biological pump, Earth system models (ESM) display significant divergence in their projections of future new production. This paper quantifies and interprets the sensitivity of projected changes in new production in an idealized global ocean-biogeochemistry model. The model includes two tracers that explicitly represent nutrient transport, light- and nutrient-limited nutrient uptake by the ecosystem (new production), and export via sinking organic particles. Globally, new production declines with warming due to reduced surface nutrient availability, as expected. However, the magnitude[...]"

 

Source: Biogeosciences
Authors: Genevieve Jay Brett et al.
DOI: https://doi.org/10.5194/bg-2020-479

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Simulating shrubs and their energy and carbon dioxide fluxes in Canada's Low Arctic with the Canadian Land Surface Scheme Including biogeochemical Cyc

Abstract.

"The Arctic is warming more rapidly than other regions of the world leading to ecosystem change including shifts in vegetation communities, permafrost degradation and alteration of tundra surface-atmosphere energy and carbon (C) fluxes, among others. However, year-round C and energy flux measurements at high-latitude sites remain rare. This poses a challenge for evaluating the impacts of climate change on Arctic tundra ecosystems and for developing and evaluating process-based models, which may be used to predict regional and global energy and C feedbacks to the climate system. Our study used 14 years of seasonal eddy covariance (EC) measurements of carbon dioxide (CO2), water and energy fluxes and winter soil chamber CO2 flux measurements at a dwarf-shrub tundra site underlain by continuous permafrost in Canada's Southern Arctic ecozone to evaluate the incorporation[...]"

Source: Biogeosciences
Authors: Gesa Meyer et al.
DOI: https://doi.org/10.5194/bg-2020-458


A transient swing to higher oxygen levels in the atmosphere and oceans at ~1.4 Ga

Abstract.

"The mid-Proterozoic (1.8–0.8 Ga) may have witnessed persistent and predominant anoxia at the Earth’s surface. However, recent studies suggest that there was a period around ~1.4 Ga where oxygen levels might have been transiently elevated, both in the atmosphere and oceans. In order to shed light on this debated topic, we analyzed rare earth elements plus Y (REY) and Cr isotope profiles of the carbonate rocks from the ~1.44-Gyr-old Tieling Formation consisting of the lower Daizhuangzi (DZZ) and upper Laohuding (LHD) Members at the Jixian section, North China. The DZZ samples are characterized by middle REE enriched, hump-shaped REY distribution patterns, while those of the LHD Member display[...]"

 

Source: Science Direct
Authors: Wei Wei et al.
DOI: https://doi.org/10.1016/j.precamres.2020.106058

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The role of environmental factors in the long-term evolution of the marine biological pump

Abstract.

"The biological pump—the transfer of atmospheric carbon dioxide to the ocean interior and marine sediments as organic carbon—plays a critical role in regulating the long-term carbon cycle, atmospheric composition and climate. Despite its centrality in the Earth system, the response of the biological pump to biotic innovation and climatic fluctuations through most stages of Earth’s history has been largely conjectural. Here we use a mechanistic model of the biological carbon pump to revisit the factors controlling the transfer efficiency of carbon from surface waters to the ocean interior and marine sediments[...]".

 

Source: Nature Geoscience 
Authours: Mojtaba Fakhraee et al.
DOI: https://doi.org/10.1038/s41561-020-00660-6

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Glacial heterogeneity in Southern Ocean carbon storage abated by fast South Indian deglacial carbon release

Abstract.

"Past changes in ocean 14C disequilibria have been suggested to reflect the Southern Ocean control on global exogenic carbon cycling. Yet, the volumetric extent of the glacial carbon pool and the deglacial mechanisms contributing to release remineralized carbon, particularly from regions with enhanced mixing today, remain insufficiently constrained. Here, we reconstruct the deglacial ventilation history of the South Indian upwelling hotspot near Kerguelen Island, using high-resolution 14C-dating of smaller-than-conventional foraminiferal samples and multi-proxy deep-ocean oxygen[...]"

 

Source: Nature Communications 
Authors: Julia Gottschalk et al.
DOI: https://doi.org/10.1038/s41467-020-20034-1

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In situ observations show vertical community structure of pelagic fauna in the eastern tropical North Atlantic off Cape Verde

Abstract.

"Distribution patterns of fragile gelatinous fauna in the open ocean remain scarcely documented. Using epi-and mesopelagic video transects in the eastern tropical North Atlantic, which features a mild but intensifying midwater oxygen minimum zone (OMZ), we established one of the first regional observations of diversity and abundance of large gelatinous zooplankton. We quantified the day and night vertical distribution of 46 taxa in relation to environmental conditions. While distribution may be driven by multiple factors, abundance peaks of individual taxa were observed in the OMZ[...]"

 

Source: Nature Scientific Reports
Authors: H. J. T. Hoving et al.
DOI: https://doi.org/10.1038/s41598-020-78255-9

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The influence of plastic pollution and ocean change on detrital decomposition

Abstract.

"Plastic pollution and ocean change have mostly been assessed separately, missing potential interactions that either enhance or reduce future impacts on ecosystem processes. Here, we used manipulative experiments with outdoor mesocosms to test hypotheses about the interactive effects of plastic pollution, ocean warming and acidification on macrophyte detrital decomposition. These experiments focused on detritus from kelp, Ecklonia radiata, and eelgrass, Zostera muelleri, and included crossed treatments of (i) no, low and high plastic pollution, (ii) current/future ocean temperatures, and (iii) ambient/future ocean partial pressure of carbon dioxide (pCO2). High levels of plastic pollution significantly reduced[...]"

 

Source: Science Direct
Authors: Sebastian G. Litchfield et al.
DOI: https://doi.org/10.1016/j.marpolbul.2020.111354

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