Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Death--Not Just Life--Important Link in Marine Ecosystems

14.04.2011
Carcasses of copepods--numerous organisms in world seas--provide insights into oceanic food webs

Tiny crustaceans called copepods rule the world, at least when it comes to oceans and estuaries.

The most numerous multi-cellular organisms in the seas, copepods are an important link between phytoplankton and fish in marine food webs.

To understand and predict how copepods respond to environmental change, scientists need to know not only how many new copepods are born, but how many are dying, say biological oceanographers David Elliott of the University of Maryland Center for Environmental Science and the Virginia Institute of Marine Science (VIMS), and Kam Tang of VIMS.

Elliott and Tang realized there was only one way to discover the answer: find the copepods' carcasses.

Mortality of copepods and other zooplankton is often assumed to be the result of predators.

Several studies have observed, however, that many dead copepods are found in samples of seawater. "This is more indicative of non-predatory mortality," says Elliott.

But traditional sampling often ignores the live/dead "status" of the copepods, Elliott says, and little is known about how many copepod carcasses are in fact floating around in the water.

Using a newly improved staining method to help distinguish between live and dead copepods in water samples from Chesapeake Bay, Elliott and Tang observed substantial numbers of intact copepod carcasses.

An average of 12 to 30 percent of the developmental stages of the abundant coastal copepod species Acartia tonsa were dead.

They found that these were likely the result of mortality for other reasons than predators.

"Using a relatively simple staining procedure to distinguish live from dead copepods, Elliott and Tang have been able to arrive at a more accurate picture of predation versus other sources of mortality for estuarine copepod populations," says David Garrison, program director in the National Science Foundation's (NSF) Division of Ocean Sciences, which funded the research.

The results were published today in the journal Marine Ecology Progress Series.

To better understand the fate of the copepod carcasses, they conducted a series of field and laboratory experiments to investigate where the copepod carcasses eventually ended up.

"We found that mixing in the water was enough to keep many carcasses in suspension in places like the shallows of Chesapeake Bay," says Elliott.

"Applying the results to the deeper open ocean, copepod carcasses become less dense as they decompose, such that they can reach neutral buoyancy and float around for some time before reaching the sea floor."

Much of the organic matter from copepods that die of non-predatory causes is recycled in sea water, he believes, rather than being directly transferred to the ocean-bottom as the remains of copepods sink.

The information on the fate of copepod carcasses was then used to estimate the rate at which copepods in Chesapeake Bay die from non-predatory causes.

Non-predatory copepod deaths accounted for more than ten percent of all mortality. The finding provides a more accurate view of how copepod abundance changes throughout the year.

"The presence of copepod carcasses in the marine environment indicates the importance of non-predatory mortality factors," says Elliott. "It represents a diversion of energy from the traditional food chain that supports fish, to one that fuels microbes.

"A better understanding of the factors causing non-predatory mortality will improve predictability of the amount of copepod prey available to fish."

That knowledge, in turn, may lead to new ways of looking at the abundance of fish in Chesapeake Bay--and beyond.

Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2010, its budget is about $6.9 billion. NSF funds reach all 50 states through grants to nearly 2,000 universities and institutions. Each year, NSF receives over 45,000 competitive requests for funding, and makes over 11,500 new funding awards. NSF also awards over $400 million in professional and service contracts yearly.

Cheryl Dybas | EurekAlert!
Further information:
http://www.nsf.gov

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>