Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Currents could disrupt ocean food chain

13.04.2005


If increased precipitation and sea surface heating from global warming disrupts the Atlantic Conveyer current – as some scientists predict – the effect on the ocean food chain in the Atlantic and other oceans could be severe, according to a new study just published in Nature.



In a worst case scenario, global productivity of phytoplankton could decrease by as much as 20 percent and in some areas, such as the North Atlantic, the loss could hit 50 percent. The study was conducted by Andreas Schmittner, an assistant professor in the College of Oceanic and Atmospheric Sciences at Oregon State University.

In his sophisticated computer model, Schmittner does not predict that the Atlantic Conveyer current, which drags warm water from the southern tropics into the North Atlantic and warms Europe, will be disrupted. Rather, his study is one of the first to examine what would happen to the ocean food chain if such a disruption did take place.


"Phytoplankton are the basis of the entire marine food web," Schmittner said. "They ultimately affect everything from zooplankton to the larger fish that people consume."

The Atlantic Conveyer current has the strongest impact in the North Atlantic, but it is a global phenomenon, Schmittner said. Surface waters from the Pacific Ocean, the Indian Ocean, the Arabian Ocean and the southern Atlantic are pulled northward where they are cooled by the atmosphere in the North Atlantic. As the water cools, it sinks 2,000 to 3,000 meters and begins flowing southward. The upwelling from the mixing of waters constantly replenishes the supply of phytoplankton at the surface, forming a rich nutrient source at the bottom of the marine food web.

There is growing concern by a number of scientists, however, that higher levels of human-generated carbon dioxide could increase water and air temperatures and decrease salinity in the North Atlantic at a rate significant enough to prevent the sinking and ultimate mixing of the water. That would not only disrupt the Atlantic Conveyer current, Schmittner said, it would prevent nutrient-rich waters from triggering phytoplankton growth.

"When the Atlantic Conveyer current works, the dead plankton sink to the bottom and are replaced at the surface with nutrient-rich water that encourages further production," Schmittner said. "When the current is disrupted, and the mixing slows, that production also is disrupted."

The shutdown of the Atlantic Conveyer current isn’t just idle speculation. A growing body of evidence suggests that it switched on and off 20 to 25 times during the last ice age.

"During the last ice age, from about 100,000 years before present to 20,000 years B.P., thick ice sheets over Canada sporadically dropped armadas of icebergs into the North Atlantic where they melted, sufficiently freshening the water to disrupt the conveyer," Schmittner said.

"There is some evidence backing that up," he added. "Deep ocean sediment core samples show pebbles from land delivered by the floating icebergs."

Schmittner said scientists also have examined ice cores from Greenland and measured isotopes that show rapid temperature changes, which coincide with changes in ocean nutrient concentrations measured in deep-sea sediment cores.

"One full oscillation of these switches took 1,500 years," Schmittner said, "but the individual transitions happened surprisingly fast. The climate went from a cold state to a warm state in as little as 20 to 50 years. Surface temperatures in Greenland increased 20 to 30 degrees Fahrenheit and water temperatures increased 10 to 20 degrees."

Schmittner said the impact of the current on the Pacific Ocean generally isn’t as great, even though the system is a global one. Still, he added, plankton production would also decrease in the Pacific if the current was reduced.

Andreas Schmittner | EurekAlert!
Further information:
http://www.osu.edu

More articles from Ecology, The Environment and Conservation:

nachricht How does the loss of species alter ecosystems?
18.05.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Excess diesel emissions bring global health & environmental impacts
16.05.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

Im Focus: Bacteria harness the lotus effect to protect themselves

Biofilms: Researchers find the causes of water-repelling properties

Dental plaque and the viscous brown slime in drainpipes are two familiar examples of bacterial biofilms. Removing such bacterial depositions from surfaces is...

Im Focus: Hydrogen Bonds Directly Detected for the First Time

For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel’s Swiss Nanoscience Institute network have reported the results in the journal Science Advances.

Hydrogen is the most common element in the universe and is an integral part of almost all organic compounds. Molecules and sections of macromolecules are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

Innovation 4.0: Shaping a humane fourth industrial revolution

17.05.2017 | Event News

Media accreditation opens for historic year at European Health Forum Gastein

16.05.2017 | Event News

 
Latest News

New approach to revolutionize the production of molecular hydrogen

22.05.2017 | Materials Sciences

Scientists enlist engineered protein to battle the MERS virus

22.05.2017 | Life Sciences

Experts explain origins of topographic relief on Earth, Mars and Titan

22.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>