Abstract.

"The French coast facing the Bay of Biscay (north-east Atlantic) is characterised by the presence of small macrotidal and turbid estuaries, including the Charente, geographically located between the two large estuaries of the Gironde and the Loire (south-west France). Multi-year, multi-site, high-frequency water quality surveys have shown that the Loire, and to a lesser extent the Gironde, suffer from summer hypoxia. These observations raised the question of the possible occurrence of hypoxia, particularly in one of these small estuaries, the Charente, which flows into the Bay of Marennes-Oléron, the first oyster-producing area in France. [...]".

Source: Biogeosciences
Authors: Sabine Schmidt & Ibrahima I. Diallo
DOI: https://doi.org/10.5194/bg-2023-150

Read the full article here.

Abstract.

"Marine hypoxia has had major consequences for both economically and ecologically critical fish species around the world. As hypoxic regions continue to grow in severity and extent, we must deepen our understanding of mechanisms driving population and community responses to major stressors. It has been shown that food availability and habitat use are the most critical components of impacts on individual fish leading to observed outcomes at higher levels of organization. However, differences within and among species in partitioning available energy for metabolic demands – or metabolic prioritization – in response to stressors are often ignored. [...]".

Source: Frontiers in Marine Science
Authors: Elizabeth Duskey
DOI: https://doi.org/10.3389/fmars.2023.1206506

Read the full article here.

Full title: "Bottom-water hypoxia in the Paracas Bay (Peru, 13.8°S) associated with seasonal and synoptic time scale variability of winds and water stratification"

Abstract.

"Coastal hypoxia can occur naturally in inshore areas of the Eastern Boundary Upwelling Systems, influenced by the nutrient-rich and low-oxygen upwelling waters. This study aims to explore the influence of water stratification and winds on bottom-water hypoxia of the Paracas Bay, an area subjected to the most intense alongshore winds and active coastal upwelling in the Peruvian coast. [...]".

Source: Science Direct
Authors: Lander Merma-Mora et al.
DOI: https://doi.org/10.1016/j.jmarsys.2023.103918

Read the full article here.

Abstract.

"Over the last 1,000 years, changing climate strongly influenced the ecosystem of coastal oceans such as the Baltic Sea. Sedimentary records revealed that changing temperatures could be linked to changing oxygen levels, spreading anoxic, oxygen-free areas in the Baltic Sea. However, the attribution of changing oxygen levels remains to be challenging. This work simulates a preindustrial period of 850 years, covering the Medieval Climate Anomaly (MCA) and the Little Ice Age using a coupled physical-biogeochemical model. [...]".

Source: Frontiers in Marine Science
Authors: Florian Börgel et al.
DOI: https://doi.org/10.3389/fmars.2023.1174039

Read the full article here.

Abstract.

"Multiple climate-driven stressors, including warming and increased nutrient delivery, are exacerbating hypoxia in coastal marine environments. Within coastal watersheds, environmental managers are particularly interested in climate impacts on terrestrial processes, which may undermine the efficacy of management actions designed to reduce eutrophication and consequent low-oxygen conditions in receiving coastal waters. However, substantial uncertainty accompanies the application of Earth system model (ESM) projections to a regional modeling framework when quantifying future changes to estuarine hypoxia due to climate change. [...]".

Source: Biogeosciences
Authors: Kyle E. Hinson et al.
DOI: https://doi.org/10.5194/bg-20-1937-2023

Read the full article here.

Full title: "Natural hypoxic conditions do not affect the respiration rates of the cold-water coral Desmophyllum pertusum (Lophelia pertusa) living in the Angola margin (Southeastern Atlantic Ocean)"

Abstract.

"Large, well-developed and flourishing reefs dominated by the cold-water coral Desmophyllum pertusum have recently been discovered along the Angola margin in the southeastern Atlantic Ocean living under very low oxygen concentrations (0.6–1.5 mL L⁻¹). This study assessed the respiration rates of this coral in a short-term (10 days) aquarium experiment under naturally [...]".

Source: Science Direct
Authors: Andrea Gori et al.
DOI: https://doi.org/10.1016/j.dsr.2023.104052

Read the full article here.

Abstract.

"Hypoxia and ocean warming are two mounting global environmental threats influencing marine ecosystems. However, the interactive effects of rising temperature and depleted dissolved oxygen (DO) on marine protists remains unknown. Here, we conducted a series of laboratory experiments on four protozoa with distinct cell sizes to investigate the combined effects of temperature (19, 22, 25, 28, and 31 °C) and oxygen availability (hypoxia, 2 mg DO L−1 and normoxia, 7 mg DO L−1) on their physiological performances (i.e., growth, ingestion, and respiration rates). The hypoxia-induced inhibition in three physiological rates increased with the biovolume of the protists. [...]".

Source: Science Direct
Authors: Cheng Qian et al.
DOI: https://doi.org/10.1016/j.scitotenv.2023.163568

Read the full article here.

Abstract. 

"Loss of oxygen in the ocean is accelerating and threatening the coral reef ecosystem. In this study, the impacts of hypoxia on the scleractinian coral Pocillopora damicornis were explored. The algal symbiont density, chlorophyll a + c2 content, energy consumption of corals, as well as energy available and consumption of their symbionts, decreased significantly post hypoxia stress. Meanwhile, the malondialdehyde contents in corals and symbionts, together with the caspase-3 activation level in corals, increased significantly in response to hypoxia stress. [...]".

Source: Science Direct
Authors: Kaidian Zhang et al.
DOI: https://doi.org/10.1016/j.marpolbul.2023.114897

Read the full article here.

Abstract. 

"The exchange of water masses between deep fjords and the open ocean is commonly constrained by a topographical barrier called the sill. While fjord water above the sill depth communicates relatively freely with the open ocean, water below the sill depth is caught inside the fjord basin. This basin water may remain stagnant in deep fjords for many successive years. During these periods, the biological consumption of dissolved oxygen is larger than the supply of new oxygen, and the fjord basin might experience hypoxia and even anoxia. [...]".

Source: Science Direct
Authors: Dag L. Aksnes et al.
DOI: https://doi.org/10.1016/j.ecss.2023.108286 

Read the full article here.

Abstract. 

"Dissolved oxygen concentrations both in the open ocean and coast have been declining due to the interaction of global climate change and human activity. Fish have evolved different adaptative strategies to cope with possibly damage induced by hypoxic environments. Black rockfish as important economic fish widely reared in the offshore sea cage, whereas related physiological response subject to hypoxia stress remained unclear. In this study, hepatic anti-oxidant enzymes (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GSH-Px]), aminotransferase (AST) and alanine aminotransferase (ALT) activities [...]".

Source: Science Direct
Authors: Yudong Jia et al.
DOI: https://doi.org/10.1016/j.aquatox.2023.106502

Read the full article here.