Oxygen Depletion Zones In Tropical Oceans Expanding

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#1
ScienceDaily (May 2, 2008) — Scientists confirm computer model predictions that oxygen-depleted zones in tropical oceans are expanding, possibly because of climate change. An international team of physical oceanographers including a researcher from Scripps Institution of Oceanography at UC San Diego has discovered that oxygen-poor regions of tropical oceans are expanding as the oceans warm, limiting the areas in which predatory fishes and other marine organisms can live or enter in search of food.

The new study is led by Lothar Stramma from the Leibniz Institute of Marine Sciences (IFM-GEOMAR) in Kiel, Germany, and is co-authored by Janet Sprintall, a physical oceanographer at Scripps Oceanography and others. The researchers found through analysis of a database of ocean oxygen measurements that levels in tropical oceans at a depth of 300 to 700 meters (985 to 2,300 feet) have declined during the past 50 years. The ecological impacts of this increase could have substantial biological and economical consequences.

"We found the largest reduction in a depth of 300 to 700 meters (985 to 2,300 feet) in the tropical northeast Atlantic, whereas the changes in the eastern Indian Ocean were much less pronounced," said Stramma. "Whether or not these observed changes in oxygen can be attributed to global warming alone is still unresolved. The reduction in oxygen may also be caused by natural processes on shorter time scales."

Sprintall said the oxygen-poor areas have the potential to move into coastal areas via currents that flow from the mid-depth tropical oceans, where the oxygen changes were observed, and along the west coast of continents.

"The width of the low-oxygen zone is expanding deeper but also shoaling toward the ocean surface," said Sprintall, a specialist in observing changes of fluxes in ocean properties such as heat distribution.

Sprintall contributed data to the study gathered during recent cruises undertaken as part of the Climate Variability and Predictability (CLIVAR) program, a long-running study operated by the World Climate Research Programme that seeks to understand climate through ocean-atmosphere interactions.

The study, "Expanding Oxygen-Minimum Zones in the Tropical Oceans," appears in the May 2 edition of the journal Science. The research team includes Stramma, Sprintall, NOAA scientist Gregory Johnson, and Volker Mohrholz from the Institute for Baltic Sea Research in Warnemünde, Germany.

The team selected ocean regions for which they could obtain the greatest amount of data to document the decline in oxygen. Some of the more recent data came from oxygen sensors which have been added to about 150 of the profiling floats used in Argo, a worldwide network of sensors that track basic ocean conditions such as temperature and salinity. There are more than 3,000 Argo floats operating in the world's oceans, and Sprintall said the quality of the data gathered by the Argo floats suggests that more units in the network should be outfitted with oxygen sensors.

Lisa Levin, a biological oceanographer at Scripps Oceanography who studies oxygen-minimum zones that intercept the seafloor, said an expansion of oxygen-minimum zones in the oceans could lead to diminished biodiversity and to the expanded distributions of organisms that have adapted to live in hypoxic, or oxygen-poor waters.

"I think it's uncharted territory," said Levin, who was not affiliated with the study. "Thicker oxygen minimum zones could affect nutrient cycling, predator-prey relationships and plankton migrations. Where the expanding oxygen-minimum zones impinge on continental margins, we could see huge ecosystem changes."

The results of the study are an important milestone for the ongoing work of the new Collaborative Research Centre (SFB 754) "Climate -- Biogeochemistry Interactions in the Tropical Ocean" funded by the German Research Foundation, which started its first phase in January 2008 in close cooperation with the University of Kiel. The SFB aims to better define the interactions between climate and biogeochemistry on a quantitative basis
Link to report - Here

--

Our grandchildren, one day, are going to go,

"Your generation was that one that fucked us over."
 
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#4
...because there's more CO2 in said area from sea plants and plankton that we overbreed from pollution and other ways. Sea plants do take oxygen you know.

Oxygen depletion could be the result of a number of factors including natural ones, but is of most concern as a consequence of pollution and as an outcome of a process known as eutrophication in which plant nutrients enter a river, lake, or ocean, phytoplankton blooms are encouraged.
=_=

In other words, my words above are true.

Sorry Salmon. ;___;
 

Rei Ayanami

Pilot Evangelion Unit-00
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#5
...because there's more CO2 in said area from sea plants and plankton that we overbreed from pollution and other ways. Sea plants do take oxygen you know.



=_=

In other words, my words above are true.

Sorry Salmon. ;___;
There's billions of humans and animals breathing air right now and it doesn't run out.

But I know what you mean.
 
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#6
But places have a lesser oxygen % than others. The air we breath isn't pure oxygen anyway, we would get ill if it was.

>.>
 

seirei

kumo no you ni
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#7
hmm, interesting...never thought this could happen o.o

so there are areas in the ocean where the % of oxygen is smaller than it should be...
I guess this means that those areas are really big, cause if they were smaller they could mix with the areas with a normal % of oxygen,without having a big impact on marine life, right?
This sounds like many fishies are going to die:em08:
 
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#8
Uh huh, as well as fishies that we haven't discovered which could be very valuable.
 

tyron256

turnabout moderation
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#9
unfortunately, things like this are happening to our world...
 

Tengu

惣流・アスカ・ラングレー
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#10
How the hell can oxygen just disappear from an area?
Quite easy, and it can be hard to replenish as there is other gas's present which stop a vacume effect from taking oxygen from surrounding area's.