The CTD returns to the ship with several gallons of pure premium Bering Sea salt water and priceless information regarding the chemistry and health of the Bering Sea.
Like her sister ship HEALY, Polar Sea'S missions include scientific and logistical support for US interests in both polar regions.
Track Polar Sea through the sea ice of the northern Bering Sea (24-hr delay)
The 75,000 horsepower ship is designed to move through 6 feet of ice at a speed of 3 knots.
The scientists and crew on Polar Sea are happy to report a successful cruise despite rough late winter weather and heavy ice in the Bering Sea.
YOUR CORRESPONDENT: Matt Sexson is a USGS biologist studying spectacled eiders as part of his PhD work at UAF. In his spare time, he's out on a US Coast Guard icebreaker, assisting BEST-BSIERP investigator Lee Cooper and his team. All photos by Matt Sexson except where noted otherwise.
ON THE AIR: KMXT Public Radio journalist Diana Gish toured Polar Sea when the ship docked in Kodiak before heading north into the Bering Sea. Listen to the story
A major component of our science mission on Polar Sea involves one of the most versatile sampling instruments on board. It’s called a CTD, which stands for Conductivity, Temperature, and Depth. It might as well be short for “collects tons o’ data,” because that's exactly what it does.
A CTD measures multiple characteristics of the water column -- including temperature, conductivity, and light penetration at various depths -- simultaneously. Plus, it can collect water at up to 12 separate depths. This water will be used by scientists who are studying aspects of the Bering Sea such as chlorophyll content, an important source of nutrients in the Arctic.
The CTD (right) is outfitted with an array of sensors and lasers, plus 12 bottles arranged in a circle. Each bottle is attached to a trigger, which when pulled seals the bottle.
As soon as we are on station, Coast Guard Marine Science Technicians (MSTs) carefully pull the CTD out of its hangar. They use a winch to carefully lift it off the deck and lower it into the water. The cable connected to the CTD can transmit data to and from a computer on the ship.
An operator monitors the CTD from the ship and directs the winch operator to lower and raise the instrument to various depths. As soon as the CTD is at depth, the operator sends a signal to the instrument to close specific bottles, capturing water from that depth.
All the while, sensors collect data that would have taken scientists hours to collect, if at all. Starting at the bottom and working its way up, the CTD returns to the ship with several gallons of pure premium Bering Sea salt water and priceless information regarding the chemistry and health of the Bering Sea. Right: Polar Sea makes her way through the sea ice, as seen from a US Coast Guard helicopter.
Want to know more about how a CTD works and what it's teaching us about the ocean? NOAA researcher Peggy Sullivan explains.
Few of us can say that we’ve walked on the Bering Sea. For sea ice biologists on Polar Sea, it happens weekly as they investigate the ecology of sea ice. Scientists reach the ice by ladder, crane, or helicopter. Towing equipment in sleds, they make their way across ice and snow adjacent to the ship. Coast Guard bear lookouts accompany the science team, just in case. All the while, the team is working in negative temperatures and strong arctic winds.
On site, scientists drill several holes in the ice using a gas powered auger (left). Various pieces of equipment are then employed to capture silt, sand, and algae that naturally falls off the underside of the ice; or to film animals that might be crawling on the underside. Finally they take water samples and measure water temperature at various depths below the ice.
Using a drill and long tubular bit, scientists also collect ice cores. The cores are cylinder shaped and about the width of a can of soup, but up to 3 feet long depending on the thickness of the ice. The cores are cut into sections representing different layers of the ice. The sections are returned to Polar Sea where they are allowed to thaw. Scientists then use microscopes to scan the resulting water for tiny animals that were living within the ice.
Growing up, I would have never thought that many animals could live in the harsh conditions of the northern Bering Sea. Maybe walrus and polar bears, but surely nothing within the ice. However, there are thousands of tiny animals living in and under the sea ice. We are just starting to learn about the importance these organisms and their ice habitat within the arctic food web.
Imagine being in a helicopter, flying over seamless sheets of ice and snow.
As the endless plain of white begins to lose its novelty, a dark oasis appears on the horizon. It isn't a lead or pool of dark blue water. It is a large mass of nearly 350,000 Spectacled Eiders in a winding lead of open water.
As you fly closer, the mass transforms into individual birds. Closer yet, you're able to discern males (black and white) and females (brown) and you begin to grasp the enormity of the flock.
Yesterday, I am confident that I saw nearly every Spectacled Eider in the world. A once in a lifetime sight! Click for larger image
From November through March, the world population of threatened Spectacled Eiders overwinters in the northern Bering Sea. Here, they depend on abundant clams and worms to survive the winter. I track their movements throughout the year using satellite transmitters that I attach to individual eiders.
On Polar Sea, we are using current locations from marked eiders to observe sea ice conditions in areas where eiders occur. The marked birds also guide our benthic sampling, which will help us better understand what eiders prefer to eat. Other biologists on this cruise are observing the sea ice in areas where eiders historically wintered, trying to learn why the population has shifted its winter distribution in the past 20 years.
One of our missions out here is to collect sediment and benthic organisms from the sea floor so we can better understand the ecology of the northern Bering. Predators including eider ducks, walrus, and fish depend on the organisms that live in and on the bottom of the ocean as a primary source of food. Changes in the distribution and abundance of the organisms on the sea floor could trigger change in populations of upper level predators or lower level prey.
A large clam-shell looking device called a Van Veen grab is lowered to the sea floor by a Coast Guard technician. Right: The grab must be sprayed with hot water as it is lowered to keep it from freezing open before it goes under the sea surface. (Tom Van Pelt)
When the grab reaches the bottom about 60 meters below, it digs into the mud and sand. When the technician retrieves the grab, the two halves close, scooping up about 30 pounds of mud and the organisms within.
Slowly the grab is brought to the surface, opened, and dumped into a large wash tub. Spoonfuls of mud are taken from the grab and later analyzed for nutrient content and sediment grain size.
Then biologists carry the tub over to a sieve, where a sea water rinse reveals buried clams, snails, worms, brittle stars, and the occasional fish or crab (right). See larger image
Sampling occurs both night and day, in temperatures that are well below freezing. Hoses and nozzles cease to work, equipment and tools freeze in place, and ice coats the gloves, face masks, and protective clothing of those fortunate enough to work on the deck.
Later, the organisms will be identified and counted to estimate their distribution and abundance across the northern Bering Sea. Samples will also be used to evaluate the diet of spectacled eiders, which are thought to depend on specific clam species to survive harsh winter conditions.
After much anticipation, Polar Sea arrived at her first sampling station yesterday. The sampling area in the northern Bering Sea is a little over 9,000 square miles in size. Within this area approximately 30 points, or stations, have been designated as sampling sites. Some of the stations are being sampled in multiple years to look at differences and similarities over time. As soon as the ship is in position, a number of teams are deployed to collect samples, with some work occurring regardless of time of day or temperature.
Sea ice scientists and their equipment leave the ship via helicopter or on a freight platform (right) attached to a crane. Researchers interested in invertebrates, water chemistry, and sediments work off the port side where a Coast Guard winch operator assists in the lowering of various nets, grabs, and instruments.
Spectacled Eider biologists survey surrounding areas for suitable ice habitat and wintering eiders. At the conclusion of each station, scientists return to labs on the ship where samples are processed, analyzed, and/or stored for future research. Then Polar Sea continues to the next station while scientists and crew process samples, rest, or visit the mess hall.
This morning was my first full shift on the benthic sampling crew, 11:30 PM (13 March) to 11:30 AM. The temperature was -9°F, with a -23°F wind chill.
East of the Pribilof Islands, Polar Sea makes her way north. As the ship drives through sea ice toward the main research area located south of St. Lawrence Island, pieces of ice sometimes 3 feet thick can be heard splitting across the bow and scraping down the port and starboard sides.
All the while, US Fish and Wildlife Service biologists scan for sea birds and marine mammals from the bridge. Over leads and pockets of open water, they spot Common Murres, Black Guillemots, and Kittlitz’s Murrelets. Seals often pop up before dipping under water again. The data collected by the Fish and Wildlife Service will contribute to our understanding of the distribution of these species in an ice filled Bering Sea.
Other scientists are busy preparing for sampling in the days to come. Scientists evaluating marine sediments, invertebrates, water, ice, and algae are setting up collection and analysis equipment on deck and in lab spaces, and Spectacled Eider biologists are using real-time satellite telemetry data to prepare for surveys by helicopter.
Aboard Polar Sea, I left Kodiak on a beautiful Sunday morning bound for the northern Bering Sea. There, the scientists and crew of the most powerful icebreaker in the US will survey for sea birds and ducks, collect invertebrate samples from the sea floor, measure aspects of the water column, and collect sea ice and algae samples.
Most of the scientists on board have been on research cruises in the past and many have been to the northern Bering in winter. As for me, this is my first cruise on a live-aboard vessel of any kind; every experience is new, most are exciting, some are gut wrenching. The rhythmic and sometimes violent roll of the ship, the endless labyrinth of passageways and stair towers, the sound of waves crushing against the bow, and the combined scent of axle grease and the mess hall are unique to this floating home away from home.
Over the next month, I’ll post log entries that describe my experiences and the science being conducted aboard Polar Sea.
The public was invited to tour the 75,000 horsepower ship when Polar Sea docked in Kodiak on 5 March. Right: Dutch Harbor. (Carin Ashjian)
The study is conducted in an area where Arctic animals such as walruses, bearded seals and spectacled eiders use sea ice as a platform to take advantage of abundant seafood on the sea floor. Changing ice conditions are likely to influence potential expansion of Bering Sea fisheries farther north as well as shrink Arctic habitat currently available on the shallow continental shelf.
Some data and samples to be collected include seafloor sediments, sea ice, and water samples and plankton. Other research includes studies of the distribution of bird and marine mammals, including the world’s population of spectacled eiders.