Overview
Rolf Gradinger studies the role sea ice algae play for Bering Sea plankton and the benthos (ocean floor). (Photo by Andrew Trites)
Above: Amphipods are small, shrimp-like crustaceans. (NOAA)
Spotlight On ... Life in the Ice
HLY0801: Healy in the Bering Sea
- March 13-26, 2008. Posted by Nora Deans
Rolf Gradinger stood for hours on the bridge, peering through binoculars and conferring with Captain Ted Lindstrom.
Slowly, Healy moved forward, sometimes slicing through thin ice, other times heaving up on top of thick, snow-covered ridges that eventually gave way under the reinforced hull, but not without slowing us to a crawl. In our wake, ice chunks turned belly up to the sky, streaked with brown -- a telltale sign that Rolf was in the right territory.
Rolf searched for the perfect ice to land the research team, and their gear. The ship nestled into the chosen spot as carefully as a 420-foot vessel can, gliding to a stop with the wind on her starboard side to keep her secure up against the ice. The engines idled, keeping her in place without cracking open new leads under the feet of the research team.
The moment the ice brow (gangway) was in place, Rolf, Sarah Story, Karen Frey, Craig Kasemodel, Jinping Zhao, Yutian Jiao and others hurried to the ice. Even while sleds of gear slid down the ramp, Rolf drilled holes through the ice - one, two, three. As others moved forward to lower equipment into the water, Rolf switched tools and started taking ice cores.
"This is the closest to the equator I've ever done research," said Rolf, an Arctic ice biologist from the University of Alaska Fairbanks who studies algae living in the ice. He suggested that their habitat -- tiny pockets of briny fluid left within the ice when sea water freezes -- is as extreme as that of a hydrothermal vent.
On this cruise he's looking to see if the same species live in the Bering Sea as in the Chukchi and Beaufort, where's he's found new species, including one named for his young daughter -- Sympagohydra tuuli.
While he hasn't studied the Bering Sea samples in detail yet, he's seeing different algae species, although in quantities he expected this time of year. At the peak of a bloom, up to 10,000 can be found in one square meter of ice. As the ice melts, the algae slip into the water where grazers can get at them. He's surprised that that he hasn't seen any tiny animals called amphipods grazing on the algae on the underside of the ice, and that euphausiids turned up under the ice in relatively shallow water.
Rolf needs more ice stations to determine snow depth and ice thickness and its influence on what lives in the ice in the eastern Bering Sea. He'll be on board for a few more weeks as part of the second Healy BSIERP-BEST cruise that departed Dutch Harbor on March 29.
Why care so much about what lives in sea ice? These tiny plankton fuel a vital food web, and in early spring sink to the seafloor, feeding clams and other creatures living in and on the mud that are eaten by walrus, eiders, gray whales, and others.
Photos, top to bottom: Sea ice, Nora Deans; gangway, Craig Kasemodel; coring ice; Christian Morel/Our Polar Heritage; ice after coring, Nora Deans.
