The URI researchers will be joined by six colleagues from the University of Massachusetts at Boston aboard the R/V Nathaniel B. Palmer, a 308-foot research ship with icebreaking capabilities. The team will observe krill swarms in the ocean and collect samples of krill at various depths in the water, assess population densities, and examine krill stomach contents to learn what and how much they eat.
“Krill are the link in the food web between the plankton and whales,” said Edward Durbin, professor of oceanography at the URI Graduate School of Oceanography and the leader of the research team. “The fjords around Antarctica have large populations of krill. We’re interested in learning about the swimming and feeding behavior of krill in different prey environments. We want to know where they go, what they eat, and how they survive in different seasons, especially winter.”
“It costs energy to swim, so we want to know whether they adjust their swimming speed depending on the prey available,” added Susanne Menden-Deuer, associate professor of oceanography. “Do they change their behavior to minimize energy expenditures when there is no food around? How fast do they swim when actively feeding on organisms in the water column?”
One important question the researchers are hoping to answer is whether krill feed on the seafloor when there is little other food available.
“There have been long discussions among scientists about what happens to krill during the winter when it’s dark,” said Durbin. “Do they sit there and slowly starve? One suggestion is that they might gain nutrition by feeding on the seafloor through the winter period. The timing of our cruise is good for examining that phenomenon because there won’t be much food in the water.”
The researchers will also use several bioacoustics devices, camera systems and nets to try to calculate the size of the krill population in the region.
“Numbers are really important. If you want to know how an organism functions in an ecosystem, it’s really important to know how many of them there are,” said Menden-Deuer. “If you want to know how much food is available or how much plankton biomass they might consume or how much organic matter may be moving in the water column, it all depends on knowing how many organisms are out there.”
Durbin said that the expedition will be challenging because no one has attempted to conduct this type of study before.
“It’s a high risk project because we don’t know if it’s actually going to work,” he said. “We’ve been building equipment and testing it in the lab to work out the kinks, but working in Antarctic conditions in 2,000 meters of water will be quite different.”
The scientists plan to return to the area in November or January to conduct similar studies to compare their results to krill feeding behavior during the Antarctic summer when plankton will be abundantly available for krill to feed upon.
In addition to Durbin and Menden-Deuer, URI oceanography faculty members Chris Roman, Tatiana Rynearson, Rebecca Robinson and Bethany Jenkins will be participating in the expedition, along with 11 graduate and undergraduate students. All will be contributing to a daily blog about the trip that can be viewed at http://krillcruise.wordpress.com.
The expedition is funded by the National Science Foundation’s Office of Polar Programs.