Some like it hot, but Arctic cod do not

A team of scientists from home and abroad headed to Alaska’s northern coast near Utqiagvik (formerly Barrow)  from the Port of Nome Nov. 7 aboard the RV Sikuliaq, a 261-ft, ice-capable research vessel. The ship, owned by the National Science Foundation and operated by University of Alaska Fairbanks is currently a base for surface and under-ice trawl surveys to study storms, ice and the food chain under the program Coastal Ocean Dynamics in the Arctic, or CODA for short.
NSF is funding the wave-ice-ocean research.
The research team, comprising scientists are working an area of Flaxman Island, Johnson islands and Icy Cape to gain more knowledge of the “new autumn” in the “new Arctic.”
Three scientists from the team—an oceanographer, a marine ecologist and a fisheries oceanographer described a project to investigate ocean dynamics and the significant coastal erosion, the loss of ice impact on food sources and the impact of the loss of sea ice on a selected keystone species— Arctic cod (called polar cod elsewhere).
The “new” Arctic is when there is less ice and the ice is slow to return, Jim Thomson, oceanographer, explained. The ice is not present to cover the water during fall storms or attached to shore to help protect loss of coast in some cases, measured in meters.
CODA is a program from University of Washington Applied Physics Lab, headed by Jim Thomson, PhD, senior principle oceanographer and lead scientist in the CODA research voyage.
Several days into the expedition, the team was working in winter conditions, against loss of light, close to time when the sun would slip below the horizon and stay for weeks, in temperatures of 6°F with a wind chill reduction to -10° F. The U.S. Coast Guard has already left the area.
Hauke Flores is an expert in the role of sea ice in Arctic ecosystems and metabolic parameters and migration patterns of polar cod and Atlantic cod.
Flores came to Nome to join the FV Sikuliaq expedition by way of a 30-hour flight from Europe. He is based at Alfred Wegener Institute in Bremerhaven, Germany.
Flores joined an information session presented by the science team at Strait Science on Nov. 5. A number of other shipboard researchers also attended the meeting, and were available for questions.
“We are interested in sea ice. Why are we interested in the sea ice and in what’s happening underneath the sea ice?  It is because sea ice is the source of life,” Flores said. People unfamiliar with sea ice or not into biology might not realize that “sea ice can host diverse community of life,” he added. “This life is supported by algae that grows inside and under the sea ice.”
The algae beneath the sea ice supports fauna that can support the food web and different kinds of animals living beneath the ice consuming the algae and each other, according to Flores.
Thus the ice produces carbon and the carbon is transferred up through the food web by tiny animals on the sea ice to fish, notably polar cod which Alaskans call Arctic cod, then to seals and to the top predator, the polar bear.
But now both the extent and the timing of the sea ice have changed.
“My personal research interest is really about this whole food chain and how time change affects the food web dynamics in this change, who are the winners and the losers from the changes that are about to come” Flores said.
This year the expedition, among other investigations, has a focus on Arctic cod, “ a cornerstone” of the arctic food chain as a staple food of seals and beluga whales, upon which subsistence food gatherers rely in the region’s coastal communities.
“Without polar cod, everything else doesn’t work anymore,” Flores said. “It’s not so interesting for fishermen, this fish, but it’s really, really interesting for all the rest of the life forms in the Arctic region.”
Arctic cod, or polar cod, have developed interesting traits, not the least interesting of which is the ability to survive in freezing conditions. They have a substance in their blood, which prevents them from freezing, according to Flores.
“This makes them very strong for surviving in a cold environment, but not so competitive when this environment warms up,” Flores said “So we are interested in finding out how the sea ice changes affect the distribution of this ecological keystone species.”
Logistical and scientific issues attend the study of the effects of sea ice on marine life. Sea ice is very dynamic in terms of distribution of types of sea ice, its physical properties and space availability when waves are moving everything around and causing stress and so on, according to Flores.
So understanding the heterogeneity of this habitat is really the key to understand how organisms are distributed in this environment, he said.
“We use ice cores to really look at the microscopic scale of what’s going on,” Flores explained.  Scientists use GoPro cameras and underwater vehicles to map the underside of sea ice, look at the different conditions and observe ice algae distribution.
The project is also using an under-the-ice trawl, produced by a member of the expedition, fitted with sensors that not only spot creatures, but also record the physical and bio-chemical properties of the sea. The trawl tool is pulled along side the ship or behind to allow it to go beneath the ice, according to Flores. The trawl allows the scientists to learn about temperatures, salinity and distribution of the algae residing both in the water and in the ice.
The sensors also yield information about the light transmission properties of the sea ice.
Hauke Flores contributes expertise on Arctic ecology and the role of sea ice in Arctic ecosystems to a project on the food sources, metabolic parameters and migration patterns of polar cod and Atlantic cod.
Franz Mueter, PhD of University of Alaska Fairbanks College of Fisheries and Ocean Sciences also shared information with the group concerning Arctic (polar) cod and the impacts of sea ice and warming in the Chukchi and Beaufort seas.
He is working to get the RV Sikuliaq set up for collecting more under-the-ice biological samples. Please stay tuned.
Strait Science is a lecture series sponsored by Northwest Campus UAF and Alaska Sea Grant.