News

'Dead zone' volume more important than area to fish, fisheries

Dubravko Justic, the Texaco Distinguished Professor in the LSU Department of Oceanography & Coastal Sciences, and Research Associate Lixia Wang recently co-authored a study suggesting that measuring the volume rather than the area of the Gulf of Mexico's dead zone, is more appropriate for monitoring its effects on marine organisms.

 

"The dead zone, a hypoxic zone, is a region of low oxygen that results from runoff of high nutrients, such as nitrogen and phosphorus, often found in fertilizer, flowing from the Mississippi River into the coastal ocean. It is the largest recurring hypoxic zone in the U.S., occurring most summers, and is located off the coast of Louisiana. This nutrient pollution, coupled with other factors, is believed to have a negative impact on fisheries because it depletes the oxygen required to support most marine life in bottom and near-bottom waters. [...]"

Source: Science Daily

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Job Offer: Postdoctoral Researcher

Postdoctoral Researcher in the area of ocean physical and biogeochemical coupling to work with Professor Resplandy in the Princeton University Geosciences department. The postdoc will investigate the physical and biological processes at both global and local scale that control the evolution of the tropical Oxygen Minimum Zone in the Indian Ocean. Details of the project can be found at https://environment.princeton.edu/grandchallenges/research/energy/dead_zones. Ideally, candidates will have a strong background in numerical modeling, but candidates with the necessary background in geophysical fluid dynamics and/or ocean biogeochemistry will be given full consideration.

Applicants should include a cover letter, a curriculum vitae including a publication list, and contact information for three references by applying at https://www.princeton.edu/acad-positions/position/9941. Applications should be received by April 15, 2019.


Tool to Capture Marine Biological Activity Gets Coastal Upgrade

"Upwelling hinders an efficient method to estimate a key measure of biological productivity in coastal waters, but accounting for surface temperatures could boost accuracy.

 

Although coastal waters make up only about 10% of the surface area of the ocean, they harbor most of its life. Measuring biological activity in these regions can reveal their impact on fisheries, low-oxygen dead zones, and the global carbon cycle, but coastal zones remain understudied. Now new research by Teeter et al. suggests how to improve the accuracy of a method that uses oxygen and argon measurements to quickly estimate marine biological activity. [...]"

Source: EOS

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Characterization of “dead-zone” eddies in the eastern tropical North Atlantic (2016)

Abstract.

"Localized open-ocean low-oxygen “dead zones” in the eastern tropical North Atlantic are recently discovered ocean features that can develop in dynamically isolated water masses within cyclonic eddies (CE) and anticyclonic mode-water eddies (ACME). Analysis of a comprehensive oxygen dataset obtained from gliders, moorings, research vessels and Argo floats reveals that “dead-zone” eddies are found in surprisingly high numbers and in a large area from about 4 to 22°N, from the shelf at the eastern boundary to 38°W. [...]"

Source: Biogeosciences
Authors: Florian Schütte et al.
DOI: 10.5194/bg-13-5865-2016

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Expanding 'dead zone' in Arabian Sea raises climate change fears

In the waters of the Arabian Sea, a vast "dead zone" the size of Scotland is expanding and scientists say climate change may be to blame. In his lab in Abu Dhabi, Zouhair Lachkar is labouring over a colourful computer model of the Gulf of Oman, showing changing temperatures, sea levels and oxygen concentrations.His models and new research unveiled earlier this year show a worrying trend.Dead zones are areas of the sea where the lack of oxygen makes it difficult for fish to survive and the one in the Arabian Sea is "is the most intense in the world," says Lachkar, a senior scientist at NYU Abu Dhabi in the capital of the United Arab Emirates.

Source: phys.org

Read the full articlere here.

 


Chesapeake Bay: Larger-than-average summer 'dead zone' forecast for 2018 after wet spring

"Ecologists from the University of Michigan and the University of Maryland Center for Environmental Science are forecasting a larger-than-average Chesapeake Bay "dead zone" in 2018, due to increased rainfall in the watershed this spring.
 

This summer's Chesapeake Bay hypoxic or dead zone, an area of low to no oxygen that can kill fish and other aquatic life, is expected to be about 1.9 cubic miles (7.9 cubic kilometers), according to the forecast released today by the two universities. [...]"

Source: Phys.org

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Gulf of Mexico 'dead zone' forecasted to exceed the size of Connecticut

"Scientists have predicted the dead zone, or area with little to no oxygen in the northern Gulf of Mexico, will become larger than the state of Connecticut by the end of July. The dead zone will cover about 6,620 square miles of the bottom of the continental shelf off Louisiana and Texas. While there are more than 500 dead zones around the world, the northern Gulf of Mexico dead zone is the second largest human-caused coastal hypoxic area in the world."

Source: Phys.org

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Physical controls on oxygen distribution and denitrification potential in the north west Arabian Sea

Abstract.

"At suboxic oxygen concentrations, key biogeochemical cycles change and denitrification becomes the dominant remineralization pathway. Earth system models predict oxygen loss across most ocean basins in the next century; oxygen minimum zones near suboxia may become suboxic and therefore denitrifying. Using an ocean glider survey and historical data, we show oxygen loss in the Gulf of Oman (from 6‐12 to < 2 μmol kg‐1) not represented in climatologies. [...]"

Source: Grophysical Research Letters
Authors: B. Y. Queste et al.
DOI: 10.1029/2017GL076666

Read the full article here.


Growing 'dead zone' confirmed by underwater robots in the Gulf of Oman

"New research reveals a growing 'dead zone' in the Gulf of Oman. Little data has been collected in the area for almost 50 years because of piracy and geopolitical tensions. The area devoid of oxygen was confirmed by underwater robots. Reasearchers found an area larger than Scotland with almost no oxygen left. The environmental disaster is worse than expected with dire consequences for fish and marine plants, plus humans who rely on the oceans for food and employment. "

Source: Science Daily

Read the full article here.


Nancy Rabalais - The "dead zone" of the Gulf of Mexico

"Ocean expert Nancy Rabalais tracks the ominously named "dead zone" in the Gulf of Mexico -- where there isn't enough oxygen in the water to support life. The Gulf has the second largest dead zone in the world; on top of killing fish and crustaceans, it's also killing fisheries in these waters. Rabalais tells us about what's causing it -- and how we can reverse its harmful effects and restore one of America's natural treasures."

Watch the full TED Talk here.


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