Navigation Links
Death -- not just life -- important link in marine ecosystems

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
National Science Foundation

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:
Related Image:
Death -- not just life -- important link in marine ecosystems
(Date:5/24/2016)... Ampronix facilitates superior patient care by providing unparalleled technology to leaders of the medical ... premium product recently added to the range of products distributed by Ampronix. ... ... ... Ampronix News ...
(Date:5/9/2016)... 2016 Elevay is currently known ... freedom for high net worth professionals seeking travel for ... connected world, there is still no substitute for a ... sealing your deal with a firm handshake. This is ... advantage of citizenship via investment programs like those offered ...
(Date:4/26/2016)... India and LONDON ... Infosys Finacle, part of EdgeVerve Systems, a product ... and Onegini today announced a partnership to integrate ... solutions.      (Logo: ... to provide their customers enhanced security to access ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... June 23, 2016   EpiBiome , a precision ... million in debt financing from Silicon Valley Bank (SVB). ... and to advance its drug development efforts, as well ... "SVB has been an incredible strategic partner ... a traditional bank would provide," said Dr. Aeron ...
(Date:6/23/2016)... 23, 2016 Apellis Pharmaceuticals, Inc. today ... trials of its complement C3 inhibitor, APL-2. The ... ascending dose studies designed to assess the safety, ... injection in healthy adult volunteers. Forty ... a single dose (ranging from 45 to 1,440mg) ...
(Date:6/23/2016)... ... 23, 2016 , ... ClinCapture, the only free validated electronic ... showcase its product’s latest features from June 26 to June 30, 2016 for ... Disrupting Clinical Trials in The Cloud during the conference. DIA (Drug Information ...
(Date:6/23/2016)... 2016 adds 2016 ... its pharmaceuticals section with historic and forecast data ... more. Complete report on the Cell ... 15 companies and supported with 261 tables and ... . The Global Cell Culture Media ...
Breaking Biology Technology: