Anaerobic Activity Is a Big Contributor in Marine “Dead Zones”

Climate models that do not account for anaerobic microbial activity may underestimate future expansion of oxygen-depleted waters.

"Certain parts of Earth’s oceans are so oxygen depleted that they can hardly sustain life. Climate models predict that these “dead zones” will expand as global warming progresses, affecting ecosystems, fisheries, and the climate itself. Now Lengger et al. provide new evidence that such predictions do not adequately account for the activity of anaerobic microbes that consume inorganic carbon within dead zones. [...]"


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Record-setting ocean warmth continued in 2019

"A new analysis shows the world's oceans were the warmest in 2019 than any other time in recorded human history, especially between the surface and a depth of 2,000 meters. The study, conducted by an international team of 14 scientists from 11 institutes across the world, also concludes that the past ten years have been the warmest on record for global ocean temperatures, with the past five years holding the highest record. [...]"

Source: EurekAlert!

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‘Dead zones’ expanding rapidly in oceans as climate emergency causes unprecedented oxygen loss

"“Dead zones” are rapidly appearing in the world’s oceans as they lose oxygen at an unprecedented rate due to climate change, sewage pollution and farming practices, presenting an existential threat to marine life and ecosystems, according to a vast new study.

The overall level of oxygen in the oceans has dropped by roughly 2 per cent, while the number of known hypoxic “dead zones” – where oxygen levels are dangerously low – has skyrocketed from 45 known sites in the 1960s to at least 700 areas now dangerously devoid of the life-giving compound, some encompassing thousands of square miles. [...]"

Source: The Independent

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World’s Oceans Are Losing Oxygen Rapidly, Study Finds

"The world’s oceans are gasping for breath, a report issued Saturday at the annual global climate talks in Madrid has concluded.

The report represents the combined efforts of 67 scientists from 17 countries and was released by the International Union for Conservation of Nature. It found that oxygen levels in the world’s oceans declined by roughly 2 percent between 1960 and 2010. The decline, called deoxygenation, is largely attributed to climate change, although other human activities are contributing to the problem. One example is so-called nutrient runoff, when too many nutrients from fertilizers used on farms and lawns wash into waterways. [...]"

Source: The New York Times

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Ocean acidification – a silently progressing crisis

"Ocean warming, acidification, deoxygenation, and marine heatwaves are all pressing marine issues that are quietly intensifying around the world. These challenges are diverse and occur on a massive scale, making it difficult for people to understand the full extent of the problem. To shed some light on this topic, the Sasakawa Peace Foundation (SPF) spoke with Mr. Tsunoda, Senior Research Fellow at the Ocean Policy Research Institute (OPRI). [...]"

Source: Sasakawa Peace Foundation

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Marine animals hold promise for extending ocean monitoring

"An international team of researchers led by the University of Exeter suggests that a wide variety of marine species could be used for monitoring the world's oceans. Using electronic tags, scientists could exploit the natural behavior of sharks, penguins, turtles, seals and other species to fill gaps in our knowledge of the seas.

With three-quarters of the Earth's surface covered with water, having a comprehensive understanding of the oceans is very important in dealing with everything from fishing quotas to climate change. The problem is that the oceans are much bigger than most people realize and many parts aren't easily, if at all, accessible."

Source: New Atlas

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A crisis in the water is decimating this once-booming fishing town

"TOMBWA, Angola — His ancestors were Portuguese colonialists who settled on this otherworldly stretch of coast, wedged between a vast desert and the southern Atlantic. They came looking for the one thing this barren region had in abundance: fish.

By the time Mario Carceija Santos was getting into the fishing business half a century later, in the 1990s, Angola had won independence and the town of Tombwa was thriving. There were 20 fish factories strung along the bay, a constellation of churches and schools, a cinema hall built in art deco, and, in the central plaza, massive drying racks for the tons upon tons of fish hauled out of the sea. [...]"

Source: The Washington Post

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Dead-zone report card reflects improving water quality in Chesapeake Bay

"An annual model-based report on "dead-zone" conditions in the Chesapeake Bay during 2019 indicates the total volume of low-oxygen, "hypoxic" water was on the high end of the normal range for 1985 to 2018, a finding that scientists consider relatively good news.


Dr. Marjy Friedrichs, a Virginia Institute of Marine Science professor and report card co-author, says "Even with environmental conditions that favor severe hypoxia, including record-high river input and light winds, our analysis shows that the total amount of hypoxia this year was within the normal range seen over the past 35 years."


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Ocean studies look at microscopic diversity and activity across entire planet

"In an effort to reverse the decline in the health of the world's oceans, the United Nations (UN) has declared 2021 to 2030 to be the Decade of Ocean Science for Sustainable Development. One key requirement for the scientific initiative is data on existing global ocean conditions. An important trove of data is already available thanks to the Tara Oceans expedition, an international, interdisciplinary enterprise that collected 35,000 samples from all the world's oceans between 2009 and 2013. The samples were collected by researchers aboard one schooner, the Tara, at depths ranging from the surface to 1,000 meters deep. [...]"

Source: Science Daily

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Extinction of cold-water corals on the Namibian shelf due to low oxygen contents

"They were also able to link this event with a shift in the Benguela upwelling system, and an associated intensification of the oxygen minimum zone in this region. The team has now published their findings in the journal Geology.

Known as 'ecosystem engineers', cold-water corals play an important role in the species diversity of the deep sea. The coral species Lophelia pertusa is significantly involved in reef formation. [...]"

Source: EurekAlert!

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