Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Discover New Trigger for Immense North Atlantic Plankton Bloom

09.07.2012
Phenomenon of spring and summer is jump-started by swirling currents of seawater

On this July 4th week, U.S. beachgoers are thronging their way to seaside resorts and parks to celebrate with holiday fireworks.


The North Atlantic Bloom: swirling artwork in the sea, phytoplankton bloom each spring southwest of Iceland. Credit: NASA Earth Observatory

Across the horizon and miles out to sea toward the north, the Atlantic Ocean's own spring and summer ritual is unfolding: the blooming of countless microscopic plant plankton, or phytoplankton.

In what's known as the North Atlantic Bloom, an immense number of phytoplankton burst into color, first "greening" then "whitening" the sea as one species follows another.

In research results published in this week's issue of the journal Science, scientists report evidence of what triggers this huge bloom.

Whirlpools, or eddies, swirl across the surface of the North Atlantic Ocean sustaining phytoplankton in the ocean's shallower waters where they can get plenty of sunlight to fuel their growth, keeping them from being pushed downward by the ocean's rough surface.

The result is a burst of spring and summer color atop the ocean's waters.

How important is the bloom to the North Atlantic Ocean and beyond--to the global carbon cycle?

Much like forests, springtime blooms of microscopic plants in the ocean absorb enormous quantities of carbon dioxide, emitting oxygen via photosynthesis.

Their growth contributes to the oceanic uptake of carbon dioxide, amounting globally to about one-third of the carbon dioxide humans put into the air each year through the burning of fossil fuels.

The North Atlantic is critical to this process; it's responsible for more than 20 percent of the ocean's uptake of carbon dioxide.

An important scientific question is how this "biological pump" for carbon might change in the future as Earth's climate evolves.

In winter, strong winds generate mixing that pushes phytoplankton into deeper waters, robbing them of sunlight but drawing up nutrients from the depths. As winter turns to spring, days are longer and plankton are exposed to more sunlight, fueling their growth.

"Our results show that the bloom starts through eddies, even before the sun begins to warm the ocean," says Amala Mahadevan, an oceanographer at the Woods Hole Oceanographic Institution in Massachusetts and lead author of the Science paper.

Co-authors of the paper are Eric D'Asaro and Craig Lee of the University of Washington, and Mary Jane Perry of the University of Maine.

The National Science Foundation (NSF) funded the research.

"Every undergraduate who takes an introductory oceanography course learns about the ecological and climate significance of the North Atlantic Bloom--as well as what causes it," says Don Rice, program director in NSF's Division of Ocean Sciences, which funded the research. "This study reminds us that, when it comes to the ocean, the things we think we know hold some big surprises."

The newly discovered mechanism helps explain the timing of the spring and summer bloom, known to mariners and fishers for centuries and clearly visible in satellite images.

It also offers a new look at why the bloom has a patchy appearance: it is shaped by eddies that, in essence, orchestrate its formation.

Making the discovery was no easy feat. "Working in the North Atlantic Ocean is challenging," says Perry, "but we were able to track a patch of seawater off Iceland and follow the progression of the bloom in a way that hadn't been done before."

"Our field work was set up with floats, gliders and research ships that all worked tightly together," adds D'Asaro. "They were in the same area, so we could put together a cohesive picture of the bloom."

The scientists focused on phytoplankton known as diatoms. Diatoms live in glass houses--walls made of silica. "When conditions are right, diatom blooms spread across hundreds of miles of ocean," says Lee, "bringing life-sustaining food to sometimes barren waters."

In April 2008, Lee, Perry and D'Asaro arrived in a storm-lashed North Atlantic aboard the Icelandic research vessel Bjarni Saemundsson.

They launched specially-designed robots in the rough seas. A float that hovered below the water's surface was also deployed. It followed the motion of the ocean, moving around, says D'Asaro, "like a giant phytoplankton."

Lurking alongside the float were six-foot-long, teardrop-shaped gliders that dove to depths of up to 1,000 meters. After each dive, the gliders, working in areas 20 to 50 kilometers around the float, rose to the surface, pointed their antennas skyward and transmitted their stored data back to shore.

The float and gliders measured the temperature, salinity and velocity of the water, and gathered information about the chemistry and biology of the bloom itself--oxygen, nitrate and the optical signatures of the phytoplankton.

Scientists aboard two ships, the Woods Hole-operated research vessel Knorr and Iceland's Bjarni Saemundsson, visited the area four times.

Soon after measurements from the float and gliders started coming in, the scientists saw that the bloom had started, even though conditions still looked winter-like.

"It was apparent that some new mechanism, other than surface warming, was behind the bloom's initiation," says D'Asaro.

To find answers, the researchers needed sophisticated computer modeling.

Enter Mahadevan, who then used three-dimensional computer models to look at information collected at sea by Perry, D'Asaro and Lee.

She generated eddies in a model, using the north-to-south variation of temperature in the ocean. The model showed that without eddies, the bloom happened several weeks later and didn't have the space and time structures actually observed in the North Atlantic.

In future research, the scientists hope to put the North Atlantic Bloom into a broader context. They believe that much could be learned by following the bloom's evolution across an entire year, especially with gliders and floats outfitted with new sensors. The sensors would look at the zooplankton that graze on a phytoplankton smorgasbord.

These data could be integrated, say the oceanographers, into models that would offer a more complete story.

"What we're learning about eddies is that they're a critical part of life in the ocean," says Perry. "They shape ocean ecosystems in countless ways."

Eddies and phytoplankton, the researchers believe, are central to the oceanic cycling of carbon, without which climate on Earth would look very different.

"We envision using gliders and floats to make measurements--and models--of ocean physics, chemistry and biology," says D'Asaro, "that span wide regions of the world ocean."

And that, says Lee, would spark a new understanding of the sea, all from tiny plankton that each spring and summer bloom by the millions and millions.

Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
Related Websites
North Atlantic Bloom Webinar Series: http://cosee.umaine.edu/programs/webinars/nab/

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2012, its budget is $7.0 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives over 50,000 competitive requests for funding, and makes about 11,000 new funding awards. NSF also awards nearly $420 million in professional and service contracts yearly.

Cheryl Dybas | EurekAlert!
Further information:
http://www.nsf.gov
http://www.nsf.gov/news/news_summ.jsp?cntn_id=124622&org=NSF&from=news

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | 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: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>