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 Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>