Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Huge iceberg wreaks havoc on Antarctic marine ecosystem, study finds

06.10.2003


For the second time in 26 months, a massive iceberg has clogged a large portion of Antarctica’s Ross Sea, causing what could turn out to be a devastating loss of penguins and other marine life, according to a NASA-funded study by Stanford scientists.



Using satellite data, geophysicists Kevin Arrigo and Gert L. van Dijken monitored the movements of a giant iceberg named "C-19," which calved off the western face of the Ross Ice Shelf in May 2002. C-19 is one of the largest icebergs ever recorded -- 19.2 miles wide and 124 miles long, or nearly twice as big as Rhode Island.

Arrigo is an assistant professor of geophysics, and van Dijken is a science and engineering associate in the department. In a study published in the American Geophysical Union’s Geophysical Research Letters, the authors described how C-19 drifted northward from May until November 2002, when it apparently ran aground. By January 2003, the iceberg had become trapped against a shallow bank, eventually forming a perpendicular barrier that prevented sea ice from moving out of the southwestern Ross Sea for the next three months -- a crucial time of year when tons of microscopic marine algae, called phytoplankton, normally bloom in open water.


Phytoplankton are a major food source for krill, which in turn are consumed by fish, seals, penguins and whales. Without massive amounts of phytoplankton, the entire food chain in the Ross Sea can collapse.

Like plants, phytoplankton grow through the process of photosynthesis, using chlorophyll to convert sunlight into food. But unusually high levels of sea ice will block sunshine, preventing phytoplankton from growing.

Green waters

To determine phytoplankton production levels in the Ross Sea, the researchers examined data from SeaWIFS -- the Sea-viewing Wide Field-of-view Sensor aboard NASA’s SeaStar satellite.

"SeaWIFS measures the amount of light coming out of the ocean at different wavelengths," noted Arrigo. "Phytoplankton contain green chlorophyll, and with SeaWIFS you can measure the intensity of the greenness of the water. The greener the water, the more phytoplankton there are."

According to the authors, SeaWIFS data from November 2002 through April 2003 revealed that the Ross Sea contained only a fraction of the chlorophyll usually seen during those months.

"Phytoplankton blooms in the region were diminished dramatically, and primary production was reduced by over 90 percent, relative to normal years," Arrigo and van Dijken wrote. The likely reason for the sharp decline, they noted, was the unusually high sea ice cover caused by C-19.

Penguins in peril

In the study, the authors cited their 2002 analysis of an even larger iceberg, called "B-15," which fell into the Ross Sea in March 2000. Using NASA data, Arrigo and van Dijken found that the excessive build up of sea ice in 2000 and 2001 had resulted in a 40 percent decline in phytoplankton productivity, which had a cascading effect on other species higher up in the food web -- including Adélie penguins. Nearly a third of the world’s total Adélie population is found in the Ross Sea.

According to the authors, the reduced phytoplankton production caused by B-15 "forced Adélie penguins to forage further form their nests, and the increased ice cover resulted in the penguins switching from a diet of predominantly silverfish to one consisting mostly of crystal krill." As a result, many Adélie colonies experienced a sharp decline in 2000 and 2001, the authors said.

"Considering that the calving of C-19 resulted in a far greater loss of production than B-15, it is likely that [penguins and other animals] that rely either directly or indirectly on phytoplankton production as a source of metabolic fuel were even more heavily impacted in 2002-03 than they had been in 2000-01," the authors concluded.

"Calving events over the last two decades indicate reduced primary productivity may be a typical consequence of large icebergs that drift through the southwestern Ross Sea during spring and summer," Arrigo added, noting that, by July 2003, C-19 had finally drifted out of the Ross Sea, having diminished little in size.

According to Arrigo, most of the face of the Ross Ice Shelf has already calved, although another large crack has appeared. However, predicting if and when another large iceberg will fall into the Ross Sea will be very difficult, he cautioned.

Rob Gutro and Krishna Ramanujan, science writers with the NASA Goddard Space Flight Center, contributed to this story.

Mark Shwartz | Stanford University

More articles from Ecology, The Environment and Conservation:

nachricht Loss of habitat causes double damage to species richness
02.04.2019 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Deep decarbonization of industry is possible with innovations
25.03.2019 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

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: Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

A stellar flare 10 times more powerful than anything seen on our sun has burst from an ultracool star almost the same size as Jupiter

  • Coolest and smallest star to produce a superflare found
  • Star is a tenth of the radius of our Sun
  • Researchers led by University of Warwick could only see...

Im Focus: Quantum simulation more stable than expected

A localization phenomenon boosts the accuracy of solving quantum many-body problems with quantum computers which are otherwise challenging for conventional computers. This brings such digital quantum simulation within reach on quantum devices available today.

Quantum computers promise to solve certain computational problems exponentially faster than any classical machine. “A particularly promising application is the...

Im Focus: Largest, fastest array of microscopic 'traffic cops' for optical communications

The technology could revolutionize how information travels through data centers and artificial intelligence networks

Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers...

Im Focus: A long-distance relationship in femtoseconds

Physicists observe how electron-hole pairs drift apart at ultrafast speed, but still remain strongly bound.

Modern electronics relies on ultrafast charge motion on ever shorter length scales. Physicists from Regensburg and Gothenburg have now succeeded in resolving a...

Im Focus: Researchers 3D print metamaterials with novel optical properties

Engineers create novel optical devices, including a moth eye-inspired omnidirectional microwave antenna

A team of engineers at Tufts University has developed a series of 3D printed metamaterials with unique microwave or optical properties that go beyond what is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

Fraunhofer FHR at the IEEE Radar Conference 2019 in Boston, USA

09.04.2019 | Event News

 
Latest News

New automated biological-sample analysis systems to accelerate disease detection

18.04.2019 | Life Sciences

Explosion on Jupiter-sized star 10 times more powerful than ever seen on our sun

18.04.2019 | Physics and Astronomy

New eDNA technology used to quickly assess coral reefs

18.04.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>