We returned to Nome on the afternoon of August 22. Our scientists successfully completed their objectives and have returned to Oregon State University, the Virginia Institute of Marine Science, UC Santa Cruz, and the Hakai Institute. This is a brief update on the last leg of the cruise before we came into port. This post was written both by Deb Greene and Kim Kenny.
While the moon passed in front of the sun and our friends across the country donned their eclipse glasses last week, the R/V Sikuliaq steamed across the Bering Sea. Fog was draped over the ship as scientists took their last measurements and began to pack up their gear. A long single blast of the foghorn went off every few minutes.
Our last full day at sea began with a blue nose ceremony. I’m not permitted to give details, but let’s just say it’s a fun way to initiate people crossing the Arctic Circle by sea for the first time. On this voyage, twelve people got their blue noses.
Later that day we passed the Crystal Serenity, a new cruise ship currently doing its second-ever trip from Seward, Alaska to New York City through the Northwest Passage.
On the Chukchi Shelf
Over this two and a half week period, the Sikuiaq’s course took us out of Nome and back again. The deepest waters we ever found ourselves in were roughly 150 meters. Most of the time we were travelling in open ocean no more than 70 meters deep, and usually much shallower.
Most sampling was done in the Chukchi Sea, the body of water above the Chukchi Shelf. Part of what makes the Chukchi Shelf unique and so interesting to study is that it’s the largest, flattest area on the entire surface of the planet. It extends down south to the Aleutian chain and north up past Barrow. It also extends north to the Chukchi Plateau and west across the top of the Siberian shelf.
Lines and Stations
Our route began with a transit from Nome into the Bering Sea, through the Bering Strait, to the Chukchi Sea until we arrived just west of Point Barrow. From there our activities followed a somewhat predictable pattern, though they call the white board on the ship where plans are written “The Board of Lies” or “The Board of Good Intentions” for good reason – sometimes plans change or adjustments are made to better suit the science. But for the most part, we towed the SuperSucker along a line for 12-24 hours depending on the length of the line. When the SuperSucker wasn’t deployed, we’d collect water using the CTD at every station along the line and collect sediment using the multi-core at every other station. There were a couple of days of steaming between lines, and the transit to and from Nome. All the while surface underway water was collected and filtered.
The SuperSucker was first deployed as we traversed across Barrow Canyon from inshore to offshore. Then the CTD was deployed at every station as we ran back over the same line offshore to inshore. Multi-core samples were taken at alternating stations.
After finishing with Barrow Canyon, we transited to just offshore of the village of Wainwright. Again we SuperSuckered away from shore, then returned to our original point running the CTD and multi-core.
Next we steamed to DBO 4 (Distributed Biological Observatory). DBO 4 is an agreed upon line of stations used by an international community of Arctic scientists to collect data. Data collected at DBO sites is shared freely by this group in order to create a more robust set of measurements. The Sikuliaq did both CTD and multi-core measurements along this line, and then ran the Supersucker back offshore.
Our next transit brought us to Hannah Shoal, where we ran the CTD and multi-core. Then we moved onto the Hannah Barrow Shoal line and ran the CTD and multi-core along the stations as we headed to the southeast. This line intersects with the Barrow Canyon line, so once there we SuperSuckered the Barrow Canyon line all the way inshore.
Once close to Barrow (Utkqiagvik), the CTD was deployed at every station. But this time, instead of multi-coring at every other station, we put in the net tow. This type of net tow is called a Tucker Trawl. It’s a mid-water tow that has a 10 foot conical net pulled behind the ship. Water depth was targeted for each tow dependent on the information interpreted off the onboard fish sonar. Zooplankton were collected in the tow and became a source of excitement after being hauled in.
At the Barrow Hannah Shoal line, we ran the SuperSucker heading northwest. We next jumped over to the Wainwright line, running the CTD at every station and towing the net at every other station; then turned around and SuperSuckered our way offshore.
Finally, we again hopped over to the DBO 4 line and ran the CTD from offshore to inshore.
In a nutshell, we ran every line twice in a methodical pattern so that we could collect the most data.
We started the journey with general knowledge and not yet fully analyzed data from last year’s cruise.
There were three big basic differences on this year’s cruise: we came earlier in the season (August instead of September), we saw no ice, and we sampled closer to shore.
On this cruise we saw two main spots of high productivity, during the transit up and along one of the lines.
Also, looking at the data collected on this voyage and comparing it to both last year and measurements taken by other research vessels, we found much warmer water temperatures.
Although data from mud sediments will not be analyzed until they can be dried back in the lab, initial layers show oxygen depletion only a few centimeters below the surface. This could be a positive sign showing productivity in the oceans. This potentially means that oxygen is being used in the marine ecosystem and therefore sediments are oxygen poor.
It’s too soon to make too many general conclusions about the scientists’ findings. The teams need time to analyze their data and collaborate on how their pieces of information fit with the bigger picture.
Thank you for following along on the second part of our Dynamic Arctic adventure. We hope it inspired you to learn more about science, the Arctic, the Sikuliaq, or was just fun to read. Happy sailing!