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