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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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Autotrophic Carbon Fixation Pathways Along the Redox Gradient in Oxygen‐Depleted Oceanic Waters

Abstract.

"Anoxic marine zones (AMZs), also known as ‘oxygen‐deficient zones’, contribute to the loss of fixed nitrogen from the ocean by anaerobic microbial processes. While these microbial processes associated with the nitrogen cycle have been extensively studied, those linked to the carbon cycle in AMZs have received much less attention, particularly the autotrophic carbon fixation —a crucial component of the carbon cycle. [...]"

Source: Environmental Microbiology Reports
Authors: Paula Ruiz‐Fernández et al.
DOI: 10.1111/1758-2229.12837

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Warming stimulates sediment denitrification at the expense of anaerobic ammonium oxidation

Abstract.

"Temperature is one of the fundamental environmental variables governing microbially mediated denitrification and anaerobic ammonium oxidation (anammox) in sediments. The GHG nitrous oxide (N2O) is produced during denitrification, but not by anammox, and knowledge of how these pathways respond to global warming remains limited. [...]"

Source: Nature Climate Change
Authors: Ehui Tan et al.
DOI: 10.1038/s41558-020-0723-2

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Observing phytoplankton via satellite

"Thanks to a new algorithm, researchers can now use satellite data to determine in which parts of the ocean certain types of phytoplankton are dominant. In addition, they can identify toxic algal blooms and assess the effects of global warming on marine plankton, allowing them to draw conclusions regarding water quality and the ramifications for the fishing industry. [...]"

Source: Science Daily

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On the co‐evolution of surface oxygen levels and animals

Abstract.

"Few topics in geobiology have been as extensively debated as the role of Earth's oxygenation in controlling when and why animals emerged and diversified. All currently described animals require oxygen for at least a portion of their life cycle. Therefore, the transition to an oxygenated planet was a prerequisite for the emergence of animals. Yet, our understanding of Earth's oxygenation and the environmental requirements of animal habitability and ecological success is currently limited; estimates for the timing of the appearance of environments sufficiently oxygenated to support ecologically stable populations of animals span a wide range, from billions of years to only a few million years before animals appear in the fossil record. [...]"

Source: Geobiology
Authors: Devon B. Cole et al.
DOI: 10.1111/gbi.12382

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Associations between redox‐sensitive trace metals and microbial communities in a Proterozoic ocean analogue

Abstract.

"Constraints on Precambrian ocean chemistry are dependent upon sediment geochemistry. However, diagenesis and metamorphism can destroy primary biosignatures, making it difficult to consider biology when interpreting geochemical data. Modern analogues for ancient ecosystems can be useful tools for identifying how sediment geochemistry records an active biosphere. The Middle Island Sinkhole (MIS) in Lake Huron is an analogue for shallow Proterozoic waters due to its low oxygen water chemistry and microbial communities that exhibit diverse metabolic functions at the sediment–water interface. [...]"

Source: Geobiology
Authors: Kathryn I. Rico
DOI: 10.1111/gbi.12388

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Anoxic metabolism after the 21st century in oxygen minimum zones

Abstract.

"Global models project a decrease of marine oxygen over the course of the 21th century. The future of marine oxygen becomes increasingly uncertain further into the future after yr 2100 , partly because ocean models differ in the way organic matter remineralisation continues under oxygen- and nitrate-free conditions. Using an Earth system model of intermediate complexity we found that under a business-as-usual CO2-emission scenario ocean deoxygenation further intensifies for several centuries until eventually ocean circulation re-establishes and marine oxygen increases again. (Oschlies et al. 2019, DOI 10.1038/s41467-019-10813-w). [...]"

Source: EGU General Assembly 2020
Authors: Wolfgang Koeve and Angela Landolfi
DOI: 10.5194/egusphere-egu2020-13038

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Temperature-related body size change of marine benthic macroinvertebrates across the Early Toarcian Anoxic Event

Abstract.

"The Toarcian Oceanic Anoxic Event (TOAE, Early Jurassic, ~182 Ma ago) was characterised by severe environmental perturbations which led to habitat degradation and extinction of marine species. Warming-induced anoxia is usually identified as main driver, but because marine life was also affected in oxygenated environments the role of raised temperature and its effects on marine life need to be addressed. [...]"

Source: Scientific Reports
Authors: Veronica Piazza et al.
DOI: 10.1038/s41598-020-61393-5

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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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