NorsemanII, image
                            from Norseman Maritime Charters
BERING STRAIT MOORINGS 2015 Cruise Blog
Norseman II

  1st - 9th July 2015, Nome to Nome,
(Cruise website)
NSF logo
NSF (National Science Foundation)
Polar Programs  PLR-1416920 and ARC-1107106. 
An NSF-supported collaboration between University of Washington (UW)  (lead PI: Rebecca Woodgate),
Massachusetts Institute of Technology (MIT)
(Co PIs: Patrick Heimbach, An Nguyen),
with links also to Oregon State University (OSU) (lead PI: Laurie Juranek and Burke Hales)

Who are we?
What are we doing?
Cruise Plan
More about the Bering Strait
Daily Report
Day 1 - Arrival in Nome Day 2/3/4 - Preparing for Sea Day Day 5 - Departure from Nome
Day 6 - In the Fog
Day 7 - Mooring recovery
Day 8 - Mooring redeployment
Day 9 - Mammals in the Strait
Day 10 - A Day in the Life of a Ship
Day 11 - Biology and Chemistry at Sea
Day 12 - Currents and Physics at sea


Ship information
   More about the Norseman 2
    Where is the ship?
Questions?
Ask us


Who are we?
Photo of Rebecca
                Woodgate
Rebecca Woodgate, UW,
Physical Oceanographer

Photo of Jim
                Johnson
Jim Johnson, UW,
Field Engineer

Photo of Kate Stafford from
                  WorldscienceFestival
Kate Stafford, UW,
Marine Mammal Acoustics
Photo of An Nguyen
An Nguyen, MIT,
Physical Oceanographer
Photo of Melania Guerra
Melania Guerra, UW,
Marine Mammal Acoustics
Photo of Maggie Buktenica
Maggie Buktenica, OSU,
Chemical Oceanographer
Photo of Max
                Showalter
Max Showalter, UW,
Biological Oceanographer
Photo of Robert
                Daniels
Robert Daniels, UW,
Physical Oceanographer




What are we doing?

Map of Bering Strait
                region schematically showing currents, adapted from
                Danielson et al
Schematic of the currents in the Bering Strait region.  We will work mainly within the yellow circle.
       The Bering Strait is the only oceanic link between the Pacific and the Arctic Oceans.  The flow through the strait brings heat (which melts ice) and nutrients (which feed Arctic ecosystems) into the Arctic.  Since 1990, we have been measuring the properties of the flow through the strait to establish the effects of this flow, and see how it is changing.  

       We do this using instruments which we deploy reaching from the sea floor (about 150ft/50m) deep to near the surface.  We combine instruments into moorings (strings of instruments, with an anchor at the bottom and floats at the top - see Figure right).  These instruments record data every hour throughout the year.  Every year we have to recover the instruments to get the data.  Then we redeploy them for the next year.  We also do a survey of the waters of the region, to check that our moorings are measuring the major properties of the flow.

       The purpose of this cruise is to recover (and then redeploy) three moorings which have been in the water since summer 2014.  Because the region is covered in sea-ice in winter, we have to do this in the summer, when the region is ice-free. The top float of the mooring must be below the surface, as otherwise it would be destroyed by the sea-ice.  Thus, we need a way of finding the moorings without being able to see them. 

How do we do this?  - follow our daily adventures (below) to find out!




Schematic of Bering Strait
                  mooring
Schematic of Bering Strait mooring

Day 1 - Arrival in Nome
Saturday 27th June 2015
Leaving Seattle
Leaving "snowless Seattle"
       The science team for this cruise comes from Seattle (WA), Corvallis (OR) and Cambridge (MA), but we join the ship in Nome, the closest port to the Bering Strait.  We fly into Nome some days before the ship, so we can prepare instruments ready to deploy. 

        Nome, originally a gold rush town, has a population of ~ 4000 with "downtown" Nome about 1.5 miles long and 0.5 mile wide, quite a contrast to the 3.6 million people in the Seattle metropolitan area.   Nome is at a latitude of ~ 64.5N.  This is below the Arctic Circle, but in summer the days are still very long - sunset is now ~ 1:40am, and sunrise only ~ 3 hrs later (4:30am).   

Cigarfish on beach in Nome      We arrive too late to start work that night, but stretching our legs along the beach, we find it covered with hundreds of ~ 6inch long sardine-like fish (see picture).  A local explained these are called "Hooligan" or "Cigar" fish.  (The name is actually a corruption of Eulachon - try saying that!) and are caught by the children, dipped in flour and fried and eaten whole.  They are also called Candle fish, as they are rich in oil and burn well, indeed the oil was traded far along the coast to California.  However, we are not quite that hungry. 

"Cigar" fish on beach in Nome
with toe of boot for scale

Arriving Nome
Arriving "snowless Nome" some 9hrs later (18hrs later from Boston)



 Day 2/3/4 - Preparing for Sea
Sunday/Monday/Tuesday 28th/29th/30th June 2015
Partially loaded shipping container
"Traveling light!" Shipping container partially filled with instrumentation and hardware transported from Seattle WA to Nome AK
Preparing electronics for deployment
Turning on and programing instruments in preparation for deployment
       When working in remote regions like the Bering Strait, a first challenge is getting all required oceanographic gear to the shipping port. For this cruise, all major instruments and hardware (all 12,000 lbs of it!, see picture on left) were sent in a shipping container by ocean barge to Nome ahead of time. These types of shipments are only possible once a month making it necessary for the scientific team to prepare and ship their equipment well in advance of the cruise (the container left Seattle at the end of April, 2 months ago). 

       Once in Nome, we unpack our shipment and sort through the gear in preparation for deployment.
Since both time and space are limited on the ship, it is important to get as much work done before leaving port. In our first three days in Nome, we perform final checks on the instruments, program them to start recording (see lower left picture), and install them in the frames in which they will be deployed (see pictures on right).   We then repack the container, so everything can be easily transported to the dock for loading into the ship.

       And now we wait for the ship.  You can track the ship's position HERE.  She is currently just past St. Lawrence Island, 100 nautical miles (115 land miles) off Nome and due in Wednesday morning.

       Another important part of any research project is to share our research goals and findings with local communities. Tonight (6:30pm), Dr. Kate Stafford will give a public presentation at the University of Alaska, Fairbanks, Northwest Campus here in Nome - "Climate Change and Whales in the Arctic".  Come if you can!

Preparing Instruments for Deployment
Preparing instrumentation for deployment
Preparing upper floatation
Preparing upper instrument and floatation for deployment





Day 5 - Departure from Nome
Wednesday 1st July 2015


Prepping the shipping container on the dock
Landing the container that holds our equipment at the dock in Nome


An ADCP being hoisted onto
                  the Norseman II
  "Flying" an instrument from the container onto the ship
      Today, the Norseman II arrives in Nome. With the ship docking in harbor, we move our equipment down to the dock in preparation for loading.

       We hoist our 12,000 pounds of equipment onto the ship with the help of the crew. Once everything (and everyone!) is on board, we listen to a briefing on safety protocols and practice an abandon-ship drill. Having all freshly trained last Tuesday on cold-water safety, we are able to climb into our survival suits (jokingly called 'Gumby suits') in almost no time. Hopefully, we never have to use our training.

       After our safety drill, we jump right into getting our instruments up and running. We are ready to set sail, strengthened by a tasty BBQ prepared by the Norseman II's cook. Bellies full, we say goodbye to Nome and head off towards the Bering Strait for the first sea day of mission. By morning, we should be at our first mooring site.


Leaving Nome Harbor
The view leaving Nome Harbor at 10:30 PM.
The
                Bow of the NorsemanII
The bow of the Norseman II.


Setting up instrumentation aboard the ship Getting the instrumentation up and running as the ship gets underway





Day 6 - CTDs in the Mist
Thursday 2nd July 2015

A view out the Porthole
A view of the Bering Strait out the porthole of the Norseman II

Robert drives a CTD
Robert controls the CTD from inside the ship

      We arrive at our mooring station this morning and are greeted by heavy fog. Because the mooring recovery requires visibility, it is too risky to attempt the mooring recovery until the fog burns off. As we wait, we take several "CTD" casts to characterize the water column at the mooring sites.

       The CTD, an instrument that measures conductivity, temperature, and depth, is the workhorse of oceanography. Temperature is (obviously!) the temperature of the water.  Conductivity (the ability of a material to pass an electric current) and temperature allow us to calculate ocean salinity (how salty the water is), while pressure serves as a measure of depth.

       The sensors of salinity, temperature, and pressure (which compose the CTD) are typically attached to a metal frame (see picture right) to protect them as they are lowered toward the seafloor.  Often times, "niskin bottles" (open ended canisters which can be shut by a signal from the ship) are also connected to this metal frame (called a rosette) to collect water samples and return them to the ship. A scientist sits on the ship at a computer connected to the instruments and tells the crew on the deck when to lower or raise the CTD. From the ship we can see this data on a computer screen in real time, which appears as plots of salt content, temperature, and pressure plotted against depth in the water (see example below right for the data from this morning).

       Data collected from CTDs are used to characterize the properties of the water.  Physical oceanographers, for example, may use this information to determine where the water is coming from in the form of currents, while those studying marine mammal acoustics need to know these properties of the water in order to understand how sound waves propagate in the sea. A biological oceanographer might deploy a CTD to study if conditions are right for an algal bloom, while chemical oceanographers use the data to support chemical analysis of water samples (e.g., as you will see later, to measure ocean acidification).

       Wait .. maybe the fog is clearing .....

A hitchhiking crested
                  auklet
A hitch-hiking Crested Auklet (Aethia cristatella) joins us aboard the ship
A CTD
                in the fog
A lonely CTD sits on the aft deck of the ship in heavy fog

 
This morning's
                CTD plot
A CTD plot shows temperature and salinity measurements with depth
- straight from this morning's cast






Day 7 - A Tale of Two Moorings
Friday 3rd July 2015
The crew hooks the mooring
The crew hooks the mooring out of the sea

Flying in the mooring to the ship deck
Using the winch, the mooring is lifted from the water onto the deck
      Last night, the fog cleared to reveal a beautifully sunny evening.  Working late into the Arctic midnight sun, we successfully completed our first mooring retrieval of the cruise. Today, our spirits are high in the new morning, but we experience a feeling of deja vu - as the day starts, we're once again surrounded by fog and forced to wait for better weather.

       As we mentioned before, our moorings rest below the sea surface to prevent collision with the thick (~ 2m) ice that covers the Bering Strait in the winter. Now, in the summer, the water is still cold (about 3 degC), but with no ice - an ideal time to recover moorings. Because we cannot see the moorings under the water's surface, we use GPS coordinates to locate them. Once we are in position,  we release the mooring from its anchor with an instrument called an acoustic release. Acoustic releases utilize sound waves to communicate with us on board the ship: an operator sends a signal to the mooring to break its connection to the anchor (the standard anchor in oceanography is an old train wheel), and the acoustic release receives and executes this command. This allows the instruments to rise to the surface (they are connected to some big floats) so we can spot them. Even though the instruments are large and brightly painted, it may still be difficult to see them in the waves of the sea, so we have all eyes on deck to look for the floats as they break the surface.

       Later into the afternoon, the fog begins to clear and we forge onward with recovering our second mooring, but not without an exciting challenge. The first release reports a problem and fails to release.  The second release - (this function is so critical, we always use two releases) - confirms it has released, but still the mooring does not surface.  We suspect that the very strong currents we are experiencing (4 knots, ~ 4 times the average current) have somehow jammed the mechanism.  Our only option is to try and knock the mooring free.   We lower hooks and weights to the sea floor.  Then paying out ~ 300m of wire and with all eyes on the water, we steam in circles around the mooring position trying to snag the anchor.  The strong current repeatedly pushes us off course.  Our hopes rise every time the wire snags on something, but to no avail.  The fog hovers near the horizon.  Hours pass, until suddenly, without warning, the mooring breaks the surface to relief all round.  However, just minutes later, the wire snags on something else. . and we now must free the wire, without losing sight of the drifting mooring.  Some intense deck operations ensue - we have snagged an old mooring anchor, weighing ~ 800kg, which is now hung up on the hooks.   But finally, we free the wire and recover it, bringing up also a stowaway sea star (below right), and we can return to the recovery of the mooring itself. 


       Once the mooring has been spotted, the ship pulls along side it. Crew members hook the floating instrument (left top) and connect it to a rope line.  The crew then uses the rope line to pull the mooring at the stern (back end) of the ship, where it can be attached to the winch. We use the winch to pull the mooring onto the ship (left bottom and below, left), and returning to us instruments which have been (we hope) recording data for the last year. 

       Before reading the data, we first have to clean the instruments off.  Any surface put into open water will be colonized by sea life, and our moorings are no exception. Barnacles, algae, and other small creatures attach to the moorings and grow in a process known as biofouling. One oceanographer's noise is another oceanographer's signal.  The biologists among us catalog the organisms growing on the moorings, and then scrape them off and return them to the sea.
 
    The mooring is pulled onto
                deckThe biofouling on the mooringStar fish comes up with the mooring trawl
(left) The recovered mooring is lowered to the deck
(center) Barnacles (~5cm long) and algae cover the moorings
(right) Our stowaway sea star joins us on deck




Day 8 - A Mooring a Day...
Saturday 4th July 2015
       This Fogbow (similar to
                rainbow) CTDing from the Norseman 2 on Bering Strait
                2015 cruisemorning, we are eager to recover our last mooring ... however, we are yet again thwarted by fog.  Our experience yesterday underlines that we must have good visibility to attempt recovery.  But we don't have it.  So instead, pushing away haunting worries about the fog remaining for the whole cruise, we collect CTD data, hoping the fog will clear later in the day.

      We run the first of our CTD "sections" (a collection of casts taken in a line - think of it as a vertical slice through the ocean).  This section is ~22 nautical miles (~24 land miles) long, crossing the US half of the strait (the remaining half of the strait is in Russian waters, where we do not have permission to work).  Stopping every nautical mile to take a cast, for the next ~ 5 hours we work (through fog) from the Diomede Islands in the center of the strait eastward toward the US coast.  There, we find the Alaskan coast is clear of fog, and even though the strait is still fogged in, we head hopefully back to the mooring site (midway between the Islands and the US coast). As we go, miraculously the fog starts to lift and a view of the full strait slowly emerges - stretching from the Russian coast in the west to the US cape, Prince of Wales, in the east, with the two beautiful Diomede islands in the middle (see photo collage below). Keeping an eye on the remaining fog, we set to recovering our last mooring - and this time, the mooring releases exactly to plan, and soon we have the mooring safely on board the ship.

      As we have been recovering moorings, we have also been redeploying to continue the data collection for another year (see photo collage left).  Though the process looks simple, details are essential, as one small mistake in assembly can result in the mooring being lost during its year in the water.    Every joint between instruments has a second safety mechanism to secure it. To  reduce corrosion, components of different metals must be electrically isolated from each other.reduce corrosion, components of different metals must be electrically isolated from each other.  Extra grab-points are included to make the mooring easier to recover.  And meticulous details are kept of all this, especially of the instruments (which we will describe in later blogs).  When all is checked and rechecked, we are ready to deploy.  With the ship steaming slowly towards the desired location, we use the ship's winch to lower the top of the mooring into the water, letting the mooring stream out on the surface behind the ship. Finally, the ship's winch lifts the anchor into the water as well.  As we reach the desired deployment site, a final tug on a rope frees the anchor from the ship's crane, the anchor plunges to the sea-floor drawing the mooring down with it, and we lose sight of it ..

Steps of Mooring
                Deployment, Bering Strait 2015, from the Norseman 2.
Steps for deploying a mooring - harder than it looks. 
The Diomede Islands
                in the center of the Bering Strait
Photo collage of the Diomede Islands, finally clear of fog in the evening.  This view is from the north, looking south. From left to right - the smaller Little Diomede (in US waters) is ~ 3 nautical miles from the larger Big Diomede  (in Russian waters).  To the far right of Big Diomede, the coast of Russia (~ 20 nautical miles away) can just be seen low on the horizon. 





Day 9 - A well "Orca-strated" Whale Watch
Sunday 5th July 2015
      Midnight sun in the Chukchi sea - sun on the
                  horizon for 2 hoursWith the mooring recoveries and deployments accomplished, our remaining tasks are the downloading (and initial quality control) of the data we have recovered from the moorings and supporting surveys of the Bering Strait region, including the southern portion of the Chukchi Sea. 

       A ship at sea never sleeps. Like the ship's crew, we split into shifts to take CTD data around the clock - those now working "nights" being compensated, when the fog lifts, by glorious midnight sun effects (left), as we are now north of the Arctic circle. 

      One of the instruments on our moorings is a hydrophone - an underwater microphone. This instrument "eavesdrops" on the underwater environment of the Bering Strait by recording the sounds that are made by marine animals, sea-ice, wind and ships. These data can provide information on the timing of migration of marine mammals that move between the Bering and Chukchi Sea or identify animals that stay in the Bering Strait region all winter, even under heavy ice and 24 hours of darkness. The data are used to study, for example, the singing behavior of bowhead whales, how sea-ice influences the occurrence of bearded seals, and how often ships move through the Bering Strait on their way to and from the Arctic. Integrating the oceanographic information obtained from other instruments on the moorings allows us to determine which environmental factors influence the presence of marine mammals.

      Although we just retrieved our hydrophones, we've already found some interesting sounds from walrus and bearded seals - you can listen to these by clicking the links on the right.

      Bridge Whale
                  Watch from the Norseman 2 Bering Strait 2015 cruiseThough again hindered by the fog, we are also making visual observations of marine mammals species (and birds).  Our marine mammal experts man the bridge from 7am to 11pm, recording numbers, species and behavior in a certain area around the ship. 
We might expect both "summer whales", those that come to the Arctic only in the summer (e.g., fin, gray, minke and humpback whales), and "winter whales", those who live year-round in the Arctic. Of particular interest is the baleen (filter-feeder) bowhead whale, so-called as they have a large hump (bow) on their heads, with which they push up sea-ice (up to 1-m thick) to create an air pocket in which to breathe!  Marine mammal sightings have been few this cruise so far, not unusual in July, but today we passed a pod of about 12 orcas (killer whales, see right). Orcas have been more abundant in the Arctic in recent years, possibly due to sea-ice retreat as their prey also move north.  Here again, the mooring data allow a year-round assessment of "who" is in the Arctic when. 

        Birds are our almost constant companions.  Bird species seen thus far include: Least, parakeet, and crested auklet; common and thick-billed murres; pigeon and black guillemots; pomarine and parasitic jaegers; short-tailed shearwaters; red phalaropes; northern fulmars; Brant geese; glaucous gulls; black legged kittiwakes; king and common eiders; and horned and tufted puffins.  But our crested Auklet has left us, probably prefering company his own size.

Bering Strait birds - Common Murres
                      (left), Pomarine Jaeger (middle) and Horned Puffin
                      (right)
Some examples of birds sighted this trip (Left: Common Murres; Middle: Pomarine Jaeger; Right: Horned Puffin)

Sounds from the Sea
Brief extracts from hydrophones on the moorings we recovered this year:

Walrus in the Bering Strait in March 2015

Bearded Seal in the Bering Strait in May 2015



Orca Sighted on July 5th
Today's sighting of orcas passing the Norseman II

Harbor Porpoise

Not Nessie - but a harbor porpoise also spotted today









Day 10 - A Day in the Life of a Research Ship
Monday 6th July 2015

      A research ship is a unique environment when compared to land: its crew must function round the clock in limited space, often on unforgiving seas. For this reason, protocol dictates certain behaviors at sea to ensure a safe and productive cruise.
A
                      cabin on the Norseman II   
  A scientist on day shift starts her morning at 0600 (6:00 AM), drawing back the black-out curtains on her bed in a shared cabin (bedroom). She heads up to the main deck as breakfast and coffee is set on the tabl
e at 0630. What is a morning meal for her is a late night snack for the night watch, who transfers over any important information of what happened over the previous 12 hours to the incoming rotation. Sitting down at the computer, she radios to the deck to prepare for the next CTD cast. Elsewhere aboard, the rest of the day shift takes their respective posts performing data quality control, mammal watch, and biofouling analyses, (or blog writing).

      Old maritime tradition gives us many of the terms we use at sea, including the rooms and equipment aboard a ship. One sleeps in a stateroom (photo left), while a bathroom is referred to as the head. The captain drives the ship from the bridge, while the cook works in the galley. At the front of the ship is the bow, and at the aft (back) of the ship is the stern. Aboard the Norseman II and other research vessels there is also a science lab where instrumentation is prepared for deployment and data are monitored.

      Actually, many nautical terms have made their way back to land.  For example, to measure speed in old times, a line (rope) was tied to a log, which was then tossed off the back of a ship. As the rope was pulled off deck, one counted the passage of knots which had been tied into the rope at regular intervals, giving rise to the nautical unit of speed over water (knots). So, every time you "log on" to a computer, you harken back to the maritime tradition of writing these log-based speeds in a "log book."


      Back in the science lab, after several hours driving the CTD, the day shift scientist receives lunch relief at 1130 - another scientist fills in for her while she eats, so CTD operations can continue uninterrupted. At the lunch table, and indeed everywhere on the ship, any loose object must be tied down, Velcroed, or placed on a non-slip surface. Cups, plates, and flatware could all turn into dangerous projectiles in rough seas. People, too, must be cognizant of the roll of the ship and develop "sea-legs"- a safety paradigm of being at sea is "one hand for yourself, one hand for the ship", i.e., always keep one hand free to steady yourself against the ship's motion.

      Of course, the ship's operations could not proceed without the dedicated efforts of the Norseman II's crew members. The Captain (The Old Man), with the help of his First Officer (Mate), directs course and heading, as well as oversees all ship's operations. In the engine room, the Chief Engineer (Chief) ensures functioning mechanical, electrical, and plumbing systems. One Bosun and two able-bodied seamen (ABs) carry out deck operations, while from a tiny galley the Chief Steward (Cook), assisted by the 2nd Cook, prepares 4 meals a day (breakfast, lunch, dinner and Midrats) for the whole crew of 16 people aboard the Norseman II. As the daytime scientist ends her shift, she sits down to dinner from 1730 to 1830 (5:30 PM to 6:30 PM). Done with her day, she transfers her watch over to the night shift, who, along with the ship's night shift, maintains continuous operations of data collection and the ship.

      And so the days roll round ...


(above,  a stateroom of the Norseman II)
Galley of the
                  Norseman II
The Galley of the Norseman II , from which comes great food.

Bridge
The Bridge of the Norseman II, from which comes great direction

The Science Lab of the Norseman II
The Lab of the Norseman II, from which comes great science



Day 11 - If it moves, it's biology; if it smells, it's chemistry ...
Tuesday 7th July 2015

      The primary mission of this research is to investigate the physical oceanography of the Bering Strait, but all disciplines of oceanography benefit from interactions with others; chemical and biological oceanography represent important elements to any oceanic study. As well as having interdisciplinary sensors on the moorings, on this cruise, we also have representatives of these disciplines to investigate oceanic nutrients and acidification, and biofouling communities, as well as to help us recognize and capitalize on moments of opportunistic science.

      Recovered interdisciplinary ins
Ocean acidification sensortruments will tell us about the year-round variation in nutrients (i.e., food for ecosystems) in the water.  Newly deployed instruments (see left) should yield the first year-round quantification of ocean acidification in the strait.  One of the many consequences of the increasing CO2 in the atmosphere is an increase in the concentration of CO2 in our oceans. Once dissolved in the ocean, CO2 reacts with the water increasing the acidity of the ocean. Increased acidity inhibits the ability of marine organisms to form shells, and the speed with which ocean acidity is increasing makes it hard for organisms to adapt.  Many of these vulnerable organisms are a vital food source for the rest of the food chain, and more research is need to predict how the system will adapt.  This is not just an Arctic problem - think about oyster beds off our coast in Washington.  However, the particular (cold, fresh) properties of Arctic waters make them more susceptible to acidification, and we are seeing the effects here sooner - a bellwether for the global ocean. 
  

       Biofouling, as previously mentioned, is the process by which organisms colonize and disrupt surfaces. Marine biofouling is especially problematic on ships, piping, marine structures, and instrumentation (such as moorings). Since the advent of seafaring, humans have made attempts to circumvent biofouling through various means - on wooden ships, a thin copper plating was common, while on more modern iron vessels (which would be corroded by copper), organotin (tin-based poisons) paints, especially the harsh chemical tributyltin oxide (TBT), were common until their ban in 2001. Today, antifouling research focuses on non-corroding copper-based paints, as well as biomimetic (bio-mimicing) materials that seek to emulate the natural antifouling qualities of, for example, shark skin.

      Tiny organic particles are the firs
Biofouling organisms from a
                  mooringt elements of biofouling - they are attracted to surfaces by electrostatic Van der Waals forces (the same forces which allow you to stick a rubber balloon to the wall once you have rubbed it on your sweater). Once the surface is coated with these tiny organic particles, bacteria chemotax (swim in response to a chemical/nutrient gradient) toward the surface and begin attaching as a biofilm (a population of stationary bacteria held together by an exuded organic glue). Algae join the bacteria, giving rise to a green or brown slimy layer, followed by larger, more recognizable creatures: barnacles, sea sponges, sea slugs, etc.. We characterize the members of this fouling community (see left) to give us a sense of how organisms are responding to changing environmental conditions in the Bering Strait over the years.

        While we are on deck transferring the CTD in and out of the water, we also keep a watch for marine life that drifts by the ship during the cast. Our most common oceanic visitors have been ctenophores ("comb-jellies", looking like small, ~ 5cm clear jellyfish of various forms, see right) and salps (clear filter-feeding swimmers, again ~ 5cm long), with also frequent sightings of up to 1m long peach-colored jellyfish.  The small, simple organisms can create dazzling displays in the water as they float by in great number.   

But with the winds increasing to strengths NOAA disturbingly calls "Small Craft Advisory", our time on deck is more focused on safely catching the CTD and getting as many stations done as we can, in case the seas come up.


(Above, top) The ocean acidification assembly from our mooring

(Above, bottom) A sample of biofouling organisms collected from a mooring,
which included an annelid worm, anemones, barnacles, algae, and hydroids


Panoramic view of the
                        Chukchi at 2AM
The Chukchi Sea at 2am, reflecting the setting sun

Ctenophore I

Ctenophore

Above: examples of the diversity of ctenophores

Image top: NOAA photo gallery, via Wikimedia commons

Image bottom: OAR/National Undesea Research Program (NURP), via Wikimedia commons






Day 12 - Filling the unforgiving minute .. with CTDs
Wednesday 8th July 2015

Final CTDing off Wales,
                  Bering Strait
CTDing off Wales, in the eastern side of the Bering Strait, looking south along our route home.

Fixing the CTD
Tending to the CTD - the operation was a success

Pair of Walrus in the Bering Strait 2015
A pair of walrus spotted today by our marine mammal observers.  A grey whale was also sighted by the Diomede Islands.
     It is 1am, and we have just brought the CTD on board for the final time, and are now steaming to Nome for offloading tomorrow.  While most of the team sleeps to be ready for final packing in the morning, the remainder run through the final data collection tasks, backing up all the data, performing initial quality control, and quickly plotting up the preliminary data to see what we have "caught".  The temptation is too great not to - we can sleep tomorrow!
 
    Over the last few days, we have taken 258 casts.  As each cast is taken, it is carefully scrutinized for any technical problemsSediment and biology in the water can jam the pumps on the CTD, compromising the data unless quickly identified.  We have had tiny stones and likely jellyfish caught in parts of the CTD, but in each case have quickly been able to fix the system (see left) without data loss.

     Our focus has been on running sections (see example right).  These are data we took this morning, along the line shown in color on the map at the top of the figure (right).  The two panels below show slices through the ocean (as if you were looking north) of the temperature and the salinity of the water. 

      Temperature and salinity
measurements are the mainstay of physical oceanography. Firstly (and very remarkably) together they tell you where waters are from - you can think of them as the "accent" of sea-water, identifying the waters' origin even after a journey around half the globe.  In our section (right), the warm, fresh waters on the eastern (right hand side) of the plot are from the Alaskan Coast, and form the Alaskan Coastal CurrentThough small in volume (only about 1/10th of the flow through the strait), this current carries ~1/12th of ALL the freshwater entering the Arctic Ocean.
     
       Secondly, from temperature and salinity, you can calculate the density of the water and, from that, gain information about the currents that are flowing.  All this information, combined with data from our moorings and also measurements of water flow we are taking from the ship during our sections, allows us to estimate not just the total volume of water, but also the amount of heat and other properties that are being carried with the water.  For example, our prior work has shown that the amount of heat carried into the Arctic through the Bering Strait has doubled between 2001 and 2011While 1/3rd of this change seems to be due to changes in the local winds, one of our goals is to find out what is causing the rest of the change.  

     

 Upper
                                                          layer
                                                          temperature in
                                                          the Chukchi
                                                          Sea in July
                                                          2015 from CTDs
                                                          of Bering
                                                          Strait 2015
                                                          cruise      The Alaskan Coastal Current is a seasonal current, and our data suggest that it has arrived in the strait in the 5 days we have been here.  This map (right) shows not only the regions we have sampled, but also the temperature in the upper layers of the ocean.  The heat within this current is thought to influence the retreat of Arctic sea-ice.  The data we have collected from the moorings should elucidate the causes and timing of these changes and will advance our understanding of how the Arctic works.

      But for now (and for many days ahead of us), we must focus on securing the highest quality of the data we have collected, and ensure that these data are available quickly and  permanently (though national data archives) for use of scientists for years to come.

      We are homeward bound, and tomorrow will disperse to our own institutions - but with a wealth of information to study
the role of the Bering Strait, the Pacific Gateway to the Arctic.

BeringStrait2015 CTD section across the northern
                Bering Strait

Sections of temperature and salinity taken this morning in the northern Bering Strait.  Top shows the line on the map.  Second and third panels show slices through the ocean as if you were looking north.  The final panel is plotting temperature against salinity, a technique which allows oceanographers to identify where waters are from.  In this final panel, the blue crosses indicate waters of the Alaskan Coastal Current, while the red dots show waters that have come from the Russian side of the Bering Sea. 

The Bering Strait,
                looking west to the Diomedes and Russia
Bye Bye Bering Strait - sunset, looking east towards the Diomede Islands, as we finally leave the Strait and head back to Nome.



For use of any of these figures, please contact Rebecca Woodgate (woodgate@apl.washington.edu)

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� Polar Science Center, University of Washington, 2015

We gratefully acknowledge financial support for this work the National Science Foundation (NSF). 
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