Sikuliaq shares a sea of surprises at Strait Science Series
Returning from a remarkable November cruise on the research vessel Sikuliaq, scientists Seth Danielson from the University of Alaska Fairbanks and Jackie Grebmeier from the University of Maryland Center for Environmental Science shared some of their findings with an audience as part of the Strait Science Series at the UAF Northwest campus.
Cruises this late in the year being quite rare, Danielson said that they “came away with some really intriguing observations, some of which might have been a little unexpected.” Digging back through the data, he found examples of previous measurements taken in 1960, but then not again until 2011.
Grebmeier said that she had never sampled in November, and that as they now go look at the data they collected, they’re “going to find some really interesting results.”
The most unexpected thing for Danielson, scientifically, was finding pockets of warm water underneath near freezing waters, seen in hydrographic cross sections. At each of the Distributed Biological Observatory sites, DBO for short, they took measurements over around 100 miles, down to the seabed, creating an image of a section of the sea. Then, they plotted temperature, salinity, density and oxygen, among others. This allowed them to see where, and at what depth, certain temperatures were. A site off the coast of Point Hope, for example, exhibited an interesting finding.
“This entire line had sea ice along it… Here, the salinity difference between the surface and the bottom is strong enough that it is maintaining stratification. We’ve got near freezing waters at the surface, and we’ve got above freezing waters at the sea floor,” Danielson said. This heat can influence ice formation.
A potential explanation for this is that the currents carried ice over the region, and that the ice didn’t form in place. Grebmeier added that heading north, they saw currents coming from the west, the center of the Chukchi Sea.
At the longest and oldest observation site, running southwest from Gambell about 200 miles into the Bering Sea, has a much different cross-section, but the middle depths of around 100-130 feet, showed a similar warmer patch. This could be explained by the salinity and density of the water beneath that.
Another scientist on the trip, Catherine Berchok, with NOAA, was “surprised by how few bowheads [she] saw, and how many gray whales and humpbacks there were out there.”
Grebmeier, agreed, saying there was much more marine mammal life than expected, describing a Minke whale up close, “nuzzling up to the side of the vessel in the moonlight with ice in the background.”
“I think we got a phenomenal amount accomplished, actually, for being just a nine day, 10 day, effort that we were able to pull together at the last minute,” Danielson concluded.
The primary goal of the voyage was to “evaluate ecosystem status and change at time series stations as part of the Distributed Biological Observatory (DBO) and deploy/retrieve NOAA moorings and Chukchi Environmental Observatory (CEO) mooring.” The cruise represented a fourth project as well, the Arctic Marine Biodiversity Observation Network.