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 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: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>