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 Making Oceans Plastic Free - Project tackles the problem of plastic pollution in the oceans
31.05.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

nachricht Nitrogen Oxides Emissions: Traffic Dramatically Underestimated as Major Polluter
31.05.2017 | Universität Innsbruck

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: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

Im Focus: Optoelectronic Inline Measurement – Accurate to the Nanometer

Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.

New Manufacturing Technologies for New Products

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

A new technique isolates neuronal activity during memory consolidation

22.06.2017 | Life Sciences

Plant inspiration could lead to flexible electronics

22.06.2017 | Materials Sciences

A rhodium-based catalyst for making organosilicon using less precious metal

22.06.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>