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 Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

nachricht International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

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: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>