Navigation Links
Death -- not just life -- important link in marine ecosystems
Date:4/13/2011

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.


'/>"/>

Contact: Cheryl Dybas
cdybas@nsf.gov
703-292-7734
National Science Foundation
Source:Eurekalert  

Related biology news :

1. Whale and dolphin death toll during Deepwater disaster may have been greatly underestimated
2. Human virus linked to deaths of endangered mountain gorillas
3. Orchid wears the scent of death
4. Jekyll and Hyde: Cells executioner can also stave off death
5. Designing new molecular tools to study the life and death of a cancer cell
6. BU School of Public Health finds simple interventions reduce newborn deaths in Africa
7. Death in the bat caves: UC Davis experts call for action against fast-moving disease
8. Cell death pathway linked to mitochondrial fusion
9. Deaths from anesthesia during childbirth plummet
10. Poor response to anti-anemia drug predicts higher risk of heart disease or death
11. Comprehensive report on sudden oak death
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Death -- not just life -- important link in marine ecosystems
(Date:6/3/2016)... LONDON , June 3, 2016 /PRNewswire/ ... Transport Management) von Nepal ... ,Angebot und Lieferung hochsicherer geprägter Kennzeichen, einschließlich ... weltweit führend in der Produktion und Implementierung ... an der Ausschreibung im Januar teilgenommen, aber ...
(Date:6/2/2016)... June 2, 2016 Perimeter Surveillance ... Unmanned Systems, Physical Infrastructure, Support & Other Service  ... visiongain offers comprehensive analysis of the global ... will generate revenues of $17.98 billion in 2016. ... Inc, a leader in software and hardware technologies for ...
(Date:5/20/2016)... 20, 2016  VoiceIt is excited to announce ... By working together, VoiceIt and VoicePass ... and VoicePass take slightly different approaches to voice ... security and usability. ... new partnership. "This marketing and technology ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... SILVER SPRING, Md. , June 23, 2016 ... evidence collected from the crime scene to track the criminal ... sick, and the U.S. Food and Drug Administration (FDA) uses ... Sound far-fetched? It,s not. ... whole genome sequencing to support investigations of foodborne illnesses. Put ...
(Date:6/23/2016)... 2016  The Biodesign Challenge (BDC), a university competition ... harness living systems and biotechnology, announced its winning teams ... New York City . The ... projects at MoMA,s Celeste Bartos Theater during the daylong ... senior curator of architecture and design, and Suzanne ...
(Date:6/23/2016)... ... , ... In a new case report published today in STEM CELLS Translational ... lymphedema after being treated for breast cancer benefitted from an injection of stem cells ... this debilitating, frequent side effect of cancer treatment. , Lymphedema refers to ...
(Date:6/23/2016)... YORK , June 23, 2016 ... trading session at 4,833.32, down 0.22%; the Dow Jones Industrial ... S&P 500 closed at 2,085.45, down 0.17%. Stock-Callers.com has initiated ... INFI ), Nektar Therapeutics (NASDAQ: NKTR ), ... Therapeutics Inc. (NASDAQ: BIND ). Learn more about ...
Breaking Biology Technology: