Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Satellites see big changes since 1980s in key element of ocean’s food chain

09.08.2002


Since the early 1980s, ocean phytoplankton concentrations that drive the marine food chain have declined substantially in many areas of open water in Northern oceans, according to a comparison of two datasets taken from satellites. At the same time, phytoplankton levels in open water areas near the equator have increased significantly. Since phytoplankton are especially concentrated in the North, the study found an overall annual decrease in phytoplankton globally.



The authors of the study, Watson Gregg, of NASA’s Goddard Space Flight Center, Greenbelt, Md., and Margarita Conkright, a scientist at the National Oceanic and Atmospheric Administration’s (NOAA) National Oceanographic Data Center, Silver Spring, Md., also discovered what appears to be an association between more recent regional climate changes, such as higher sea surface temperatures and reductions in surface winds, and areas where phytoplankton levels have dropped.

Phytoplankton consist of many diverse species of microscopic free-floating marine plants that serve as food to other ocean-living forms of life. "The whole marine food chain depends on the health and productivity of the phytoplankton," Gregg said.


The researchers compared two sets of satellite data -- one from 1979 to 1986 and the other from 1997 to 2000 -- that measured global ocean chlorophyll, the green pigment in plants that absorbs the Sun’s rays for energy during photosynthesis. The earlier dataset came from the Coastal Zone Color Scanner (CZCS) aboard NASA’s Nimbus-7 satellite, while the latter dataset was from the Sea-Viewing Wide Field of View Sensor (SeaWiFS) on the OrbView-2 satellite.

The researchers re-analyzed the CZCS data with the same processing methods used for the SeaWiFS data, and then blended both satellite measurements with surface observations of chlorophyll from ocean buoys and research vessels over corresponding time periods. By doing so, the researchers reduced errors and made the two records compatible.

Results indicated that phytoplankton in the North Pacific Ocean dropped by over 30 percent during summer from the mid- 80s to the present. Phytoplankton fell by 14 percent in the North Atlantic Ocean over the same time period.

Also, summer plankton concentrations rose by over 50 percent in both the Northern Indian and the Equatorial Atlantic Oceans since the mid-80s. Large areas of the Indian Ocean showed substantial increases during all four seasons.

"This is the first time that we are really talking about the ocean chlorophyll and showing that the ocean’s biology is changing, possibly as a result of climate change," said Conkright. The researchers add that it remains unclear whether the changes are due to a longer-term climate change or a shorter-term ocean cycle.

Phytoplankton thrive when sunlight is optimal and nutrients from lower layers of the ocean get mixed up to the surface. Higher sea surface temperatures can reduce the availability of nutrients by creating a warmer surface layer of water. A warmer ocean surface layer reduces mixing with cooler, deeper nutrient-rich waters. Throughout the year, winds can stir up surface waters, and create upwelling of nutrients from below, which also add to blooms. A reduction in winds can also limit the availability of nutrients.

For example, in the North Pacific, summer sea surface temperatures were .4 degrees Celsius (.7 Fahrenheit) warmer from the early 1980s to 2000, and average spring wind stresses on the ocean decreased by about 8 percent, which may have caused the declines in summer plankton levels in that region.

Phytoplankton currently account for half the transfer of carbon dioxide from the atmosphere back into the biosphere by photosynthesis, a process in which plants absorb carbon dioxide (CO2) from the air for growth. Since carbon dioxide acts as a heat-trapping gas in the atmosphere, the role phytoplankton play in removing carbon dioxide from the atmosphere helps reduce the rate at which CO2 accumulates in the atmosphere, and may help mitigate global warming.

The paper appears in the current issue of Geophysical Research Letters.



David E. Steitz | EurekAlert!
Further information:
http://www.gsfc.nasa.gov/topstory/20020801plankton.html

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 >>>