Bering Sea Ice Expedition 2007

An abundance of cameras for all the photos taken during this Bering Sea Expedition.

A plethora of photo equipment on this cruise. Photo by D.Hyrenbach

** USCGC Healy: Saturday, May 12, 2007 (see images for this day)

This morning we were awakened by the rumbling noise of the Healy docking. We finished packing,cleaned our state rooms, said our farewells to the crew of the Healy and to the scientists staying onboard for the next expedition. Then we made our way to the airport. Once we get home, we will start analyzing the megabytes and megabytes of data we have collected in the last 33 days at sea. This includes organizing all of our digital photos. We had many avid photographers equipped with a vast array of photographic equipment. As a result, we stored over 7000 digital photographs on the Healy's public computer drive. Link here to see some of the most spectacular photos from this cruise.

We are rapidly approaching the end of the cruise, as we continue to sail southwest towards deep water off the continental shelf. During this transect, we have crossed a marked front over the shelf-break (200 m depth), characterized by an increase in near-surface water temperature (from 2.0-2.4 to 3.4-3.4 degrees C) and salinity (from 31.2-31.4 to 31.8-32.0 p.s.u.).

Even though the cooler and fresher water from the sea ice melt on the shelf was replaced by warmer water offshore, we did not encounter the patch of Walleye Pollock larvae we had been hoping for. The series of seven CTD/net tow stations along this onshore-offshore line yielded only several eggs and one larva (with a size of 4.41 mm; see photograph at right from a different cruise). This result suggests that the fish had not spawned in this area yet. Nevertheless, the acoustics data collected during the cruise will give NOAA researchers information on the distribution and abundance of adult fish within the study area. Together with the CTD data, the acoustics information will help fishery managers determine whether the adult fish may have shifted their distributions during the spring of 2007, possibly in response to the large extent of cold water on the shelf.

Walleye Pollock are schooling fish, occurring between 100-300 m depth. The adult fish generally move inshore during summer and offshore in winter, occupying greater depths during the cold-water months. Spawning occurs at different seasons depending upon the geographic location; in Alaska it happens between March and May. Females spawn in several batches over a few weeks, producing up to 2 million eggs each. The eggs hatch in 1-3 weeks at the depth of spawning (usually 100-250 m), and the larvae develop in shallow water (< 30m). Young-of-the-year juveniles feed on plankton near the surface at night and descend deeper in the water column during the day. To learn more about the ecology and the fishery for Walleye Pollock, visit the NOAA/AFSC Walleye Pollock Research page.

Above the water surface, the weather has turned worse and worse during the day. As if the Bering Sea wanted to remind us of what it is capable of, the Healy has been battered by big seas and 40 knot winds. All the scientists are busy packing their gear and backing-up data, thankful there are no more CTD casts and net tows to do in this weather. We will be in Dutch Harbor tomorrow morning, and many of us fly out in the early afternoon as our cruise comes to completion.

We have been sailing towards the southwest, running an 180 nautical mile (335 kilometer) across-shelf transect, from the inner shelf (40 m depth) to the slope (2000 m depth). We are going to stop every 30 nautical miles for a station, where we will complete a CTD cast (CTD cast movie)and a bongo net tow. Like the percussion instrument of the same name, these nets consist of two separate circular frames and nets, which allow researchers to obtain two distinct samples (bongo net deployment movie).

For example, one sample is stored in formalin and used to quantify the presence and abundance of zooplankton, and the other sample is frozen to perform population genetics analyses. Alternatively, each bongo is equipped with a different mesh net to filter different size classes of plankton, such as the young stages of copepods (copepodites). During this cruise, we have equipped the bongos with additional sensors to enhance our ability to interpret the plankton abundance data. Flow meters are used to quantify the amount of water going through each of the nets, which then allows researchers to calculate a normalized metric of plankton abundance (biomass = grams of wet weight of plankton for 1000 cubic centimeters of water filtered). A seacat CTD sensor is used to measure the

temperature and salinity in the water column, as the net makes its way through the water column. These profiles provide information on the physical structure of the water column where the plankton were collected.

We have sampled about half of the seven stations long this line, and have collected lots of phytoplankton in the cod end (see the attached photo of the greenish soup in the bucket) but no traces of pollock larvae. We did find some Pollock eggs in the middle of the shelf, but no larval fish yet. Once we encounter a patch of larvae, we will sample it repeatedly to harvest specimens for studies of their condition and genetics. We will continue with this sampling plan until we reach the deep water offshore of the shelf.

Offshore of the shelf-break (200 m depth contour), we will deploy the iron vane for the last time, to measure traces of iron in the water column, which researchers believe are advected onshore by currents. We also anticipate crossing a temperature and salinity front along the shelf break, with warmer and saltier water offshore. Over these deep waters we also expect to encounter oceanic birds, including our last look at storm-petrels and albatrosses, and perhaps some fin whales.

We have been sailing eastward toward Bristol Bay, through dense fog and snow fall. Even though the visibility is very low (200-300 meters), the flat seas and gentle swell make for pretty good conditions for whale detection. However, we have only seen a group of harbor porpoise since we left the ice. Our eyes are peeled for cetaceans, especially the highly-endangered northern right whales, as well as for short-tailed shearwaters. An estimated 6-20 million of these far-ranging seabirds migrate each year from their breeding grounds in Tasmania and South Australia to the Bering Sea, where they molt

their feathers and spend the austral winter. Large flocks of shearwaters forage on euphausiids and forage fish, often in association with humpback whales. We have not seen any yet, but we hope to encounter some shearwaters and whales farther west, when we approach the shelf-break on our way back to Dutch Harbor.

Before the weather took a turn back into winter-time conditions, we took advantage of the warm conditions and got an outdoor group photo of this cruises' participants. All the scientists and Healy crew gathered on the helicopter deck of the Healy (see photo right) . By now, the deck is a more appropriate place for a snow ball fight; 1-2 inches of snow have built up in the last day.

The science is winding down as we approach our destination: everybody is processing the final samples of the cruise and packing up the equipment. Yet, some of the scientists have been conducting additional experiments with the last supplies of liquid nitrogen. Manufacturing ice cream and juice sorbet are some of the unexpected benefits of the cruise wrap up.

But not all of the science is done onboard the Healy. The acoustic/seabird surveys will continue until we run the final CN (Cape Newenham) line on Thursday/Friday. In fact, one study has not even begun yet. Fisheries scientists from the Alaska Fisheries Science Center (NOAA/AFSC) in Seattle, will sample the CN line with CTDs and net tows in search of pollock and crab larvae. In addition to sampling the water column with standardized oblique net tows to obtain a quantifiable metrics of larval abundance in the water column, the scientists are planning a series of adaptive tows to obtain specimens for studies of natural history and population genetics. The objective of this research is to understand what oceanographic conditions enhance the survivorship of these larvae, and eventually their recruitment to the population in the southeastern Bering Sea shelf. In particular, researchers are focusing on the influence of water temperature on larval conditions and survivorship, and plan to investigate whether larvae in colder and warmer waters have genetic differences that make them better suited for living in these different conditions. Came back tomorrow to find out more about pollock larvae and other cruise results.

Today is Tuesday once more, and the beginning of our fifth and final week onboard the Healy. Today we completed the 200th station of the cruise, well beyond the 187 we originally anticipated, and the count will go on all the way back to Dutch Harbor.

We experienced the last signs of winter today. In the morning, we woke up with a thick carpet of snow covering the decks of the Healy and a blanket of fog surrounding us. We were at the eastern end of the shelf, off Nunivak Island, and the morning helicopter flight had to be cancelled. Later on in

the afternoon, three final helicopter seal surveys took place. In the meantime, the Healy encountered scattered groups of walrus (pairs and trios) swimming in open water. These encounters culminated with the sighting of a large group (approximately 50 animals) resting on the ice. We waved farewell to the walrus and started sailing to the south and west, heading towards the Pribilof Islands.

Throughout the day, it was evident that we were heading into open water. The ice looked frail and tired, and the open water leads and pools seemed to be getting progressively larger and larger. At 11:15 at night we finally crossed into open water, leaving the ice edge behind us. The seal observations and the ice log are done for the cruise. Only the hydrographic observations (underway and CTD stations), the net tows for zooplankton and larval fish, and the seabird observations will go on for the next three days.

In the evening, we held a meeting in the science conference room to discuss some of the findings during the cruise and how they relate to the larger objectives of the Bering Sea Ecosystem Study (BEST) program. For more information about the program's goals and ecological change in the Bering Sea, please visit these web-sites:

Today we have sailed through alternating areas of young ice (grayish, thin and frail) and thicker

jumbled up pack, as we make our way eastwards towards Nunivak Island. During our transit, we have encountered thousands of murres aligned in strings and flying high off the water; they cross our track heading north and east, possibly returning to their breeding colonies in St. Matthew and St. Lawrence Islands.

In the afternoon, we completed the seventh ice coring station of the cruise in a location with some jumbled up ice and open water leads. The scientists on the ice noticed brown stains, which they attributed to ice-associated diatoms. Upon closer inspection, they found the same brownish strands in the water. By collecting a sample, Ray Sambrotto was able to identify the phytoplankton responsible for these strands: the pagophylic (or ice loving) diatom species Melosira arctica. See the close-up photograph from the microscope.

In the evening, we continued making our way eastwards, sampling hydrographic stations every 30 nautical miles (54 kilometers). Even though some of the research programs like the mud multi-corer have completed their work, other groups onboard the Healy will continue sampling until we reach Dutch Harbor. In particular, we anticipate completing a series of CTD and net tow stations in Bristol Bay, to compare the current conditions with those we encountered at the beginning of the cruise.

Sunday is a great day for a BBQ - even in the middle of the Bering Sea. We rolled the helicopter out

onto the helo pad and set up a lunch-time feast in the hanger. Despite the fog and the chilly air temperatures, the grilled goodies (hot dogs, hamburgers, veggie burgers, chicken patties) and assorted salads got us in a spring-time mood.

While the BBQ was being set up, we deployed a group of scientists onto the ice to take ice cores and water samples. The rescue diver and bear watch-man were deployed to keep an eye out for the scientists working in the fog. This was the sixth ice coring station of the cruise, and was completed without a glitch. After lunch, we set sail again towards our final destination: Dutch Harbor is five days away.

We spent most of the day sailing southwards along the 70-m isobath, making our way through heavy ice, jumbled up into high piles, and a heavy snow fall. It was a far cry from the spring-time conditions ideal for seabird/seal observations (and BBQs). In fact, the fog was so thick that the helicopter flights were cancelled for the day. Nevertheless, the seal and bird observers continued their watches from the bridge. Most of the birds we encountered were northern fulmars flying high off the ice, possibly individuals prospecting their colonies on St. Matthew and Hall Islands.

In spite of the winter-time weather conditions, the satellite imagery from the Special Sensor Microwave/Imager (SSM/I) reveals drastic changes in the sea ice during the

last two weeks. This satellite, capable of mapping sea ice concentrations through clouds and fog, shows that the sea ice has disappeared from large areas of the shelf, creating two large open water gaps south of Saint Matthew Island (SM) and north of Nunivak Island (NI). When we consider this larger-scale picture, we realize that we have been sailing through the last pocket of dense sea ice (80%-90% cover) left in the southeastern Bering Sea shelf this year. You can see the ship track to the SE of Saint Matthew Island (SM) on the "late" panel to the right. Once more, the satellites overhead give us a very different perspective than the view from the bridge of the Healy.

Cinco de Mayo on the Healy. To give the cooks a rest, the crew of the Healy takes turns preparing dinner every Saturday night. Today is the turn of the scientific party, and we are making a Mexican

feast with enchiladas, chili, quesadillas, churros and flan. In addition to cooking, we did get some "ciencia" done.

Today we traversed a very heterogeneous landscape, with ever changing types and amounts of ice. In the morning, we started out in open water. Later on in the day, we encountered thick pieces of sea ice (up to 3 m or 9 feet thick) jumbled up into huge piles. Only the occasional fulmar/murre flew by and a ribbon/spotted seal sat on the ice. The area of jumbled ice eventually gave way to a vast expanse of thin grayish ice, with the bearded seals resting on some of the thicker ice cakes embedded in this matrix of ice (see Healy aloft camera for hourly ice photos).

At the end of the Nunivak line (NI), David Shull and Allan Duval deployed the multi-corer for the final time this cruise. They have performed over 25 drops and have retrieved approximately 4000 pounds of mud from the Bering Sea shelf and slope. This is equivalent to the weight of a small walrus, or for those not accustomed to this unit of mass, about the weight of a VW bug. Check out some of the organisms that Jerry McCormick-Ray has found in the mud, including worms, echinoderms, mollusks and foraminifera (note: the organisms are not all shown at the same scale in the photos).

After making our way to the west of the Nunivak line, we took a right-hand turn towards the 70-m

isobath line west of St. Matthew Island. During this transit, we revisited a series of CTD/net tow stations we sampled about 10 days ago. Since our first visit, the ice has retreated and the near-surface water temperatures (8 m deep) had warmed substantially (by 1 to 2 degrees C). Check out the map comparing the near-surface water temperatures in the early and the late time periods of the cruise.

Throughout the day, we encountered different types of seals: ribbon, spotted and bearded. Even the walrus made a come back in the evening, once we encountered the thicker and jumbled ice pack. The seal team deployed their small boats and tagged a ribbon seal in the afternoon; the third one during this trip. Check out the photos of the seal team in action on our Images-of-the-Day.

The Healy is heading due west towards the shelf-break along the Nunivak Island (NI) line. Tonight, we will take a right-hand turn and start heading northeast towards the northern end of the 70-m isobath transect. We occupied this line earlier in the cruise. This 70-meter isobath line (70-m map) bisects the middle shelf from south to north (Bristol Bay to St. Lawrence Island) and connects the four oceanographic moorings. A second transect along this line will allow us to investigate how the physical and biological conditions have changed during the last two weeks. As we move into spring and the sea ice retreats, we anticipate that the belt of high chlorophyll concentrations will migrate northwards with the ice-edge bloom. We also expect to find the tell-tale signs that the bloom has come and gone farther south via depleted nutrients (nitrate and silicate) near the surface, high chlorophyll concentrations at depth (from the sinking phytoplankton), and higher levels of recycled nutrients (ammonium) in the water column.

In addition to the progressive northward shift of the ice edge, we have observed from the remote sensing imagery the "rotting out" of the ice and the formation of large open water areas. As we now return north, it is really apparent that the ice-covered shelf is opening up in front of our eyes. What once was ice pack with scattered open water leads, now resembles a layer of swiss cheese with popcorn sprinkled over the top.

As the Healy sails through this disorganized and jumbled mess, the punctured ice cakes appear fragile and tired. The water column, on the other hand, is teeming with activity and productivity. Check out the microscope photos of phytoplankton. Under water, the submerged ice ledges are covered by the brownish stains of the ice algae. Above the water, ribbon and spotted seals rest on the jumbled ice; perhaps wondering how much longer they will be able to bask in the sun.

The day started with a PolarTREC live event in the science library. The two teachers onboard, Maggie and Robyn, use the iridium phone connection in a conference call to get in touch with teachers and school children across the country and abroad. Today's guests were the Healy's

Captain Lindstrom and our chief scientist (Ray Sambrotto). We have held three of these events thus far, and have scheduled one additional event on the last day of the cruise (May 11th). Together with the blogs available online, these live events allow Maggie and Robyn to bring our work and experiences into classrooms, increasing the educational and outreach impacts of this research.

In the afternoon, we held a science meeting to review the progress to date and to discuss the next steps for the cruise. All the researchers are very satisfied with the amount of work we have completed thus far. Working from the Healy has allowed us to cover a lot of ground because this vessel can cruise at high speed (8-12 knots) in ice-covered regions. Furthermore, we have been very fortunate and have not

experienced any weather delays, which often happens during research cruises. With nine days left in the cruise, our top priorities are to take more ice core samples in the area close to Saint Lawrence Island, re-sample the stations along the 70-m isobath transect, and revisit some of the stations we sampled in the early part of the cruise in Bristol Bay as we head south.

This evening we completed station number 164, which included a CTD cast, net tows, a deployment of the iron vane and two multi-core drops. This was a fairly shallow station (91 meters or 273 feet) at the outer-most (offshore) end of a line zigg-zagging across the shelf. Tonight, we will transit northeast back towards the ice and the

shallow water, where we will eventually rejoin the Nunivak Island (NI) line.

As we approach ice-covered regions of the shelf, the Healy comes within helicopter range of seal and walrus habitat. We have been launching two helicopter flights each day to explore sea ice conditions and to survey for seals and walrus over vast expanses of the shelf. These flights, which usually last up to 2 hours, provide the Healy with a larger-scale perspective of the surrounding sea ice conditions. Check out some of the sea ice photos (today and prior days) from the helicopter. NOAA researchers will use these surveys to develop population abundance indices for ice seals, and to study their associations with different sea ice habitats.

Today we traversed the continental slope and the shelf break in the area of Zhemchug Canyon, and traveled northwards towards the ice-covered region of the shelf. Large numbers (hundreds) of gulls aggregated around the Healy during the deep stations. They seemed disappointed when the CTD or the multi-core emerged from the water. Such a long wait deserves, well, a fish...or two. The

researchers also wait long hours for the samples to come up from depth. Once they are onboard, a frenzy of activity begins.

During this 245 nautical mile (132 kilometer) offshore-onshore transect, we traversed three regions with distinct physical characteristics and faunas:

In addition to these changes in the type and amount of sea ice, we traveled along the shelf break (at 200-m depth contour). We encountered the highest bird densities along this steep bathymetric gradient, with murres and gulls concentrated along a fairly narrow (5-10 km) band. We also encountered a frontal area, separating different water masses, immediately onshore of Zhemchug canyon. We saw some bull kelp and two pieces of marine debris (a piece of plastic and a float), which suggest that this was an area where bouyant material was concentrated and retained by surface currents.

We encountered another frontal zone during the northward transit along the 70-meter isobath, when we crossed from warmer waters to the south, to cooler waters to the north. South of this frontal system a phytoplankton bloom, characterized by high chlorophyll concentrations and elevated oxygen saturation levels near the surface, was underway. We hope to revisit this area on our way back to Dutch Harbor, to determine how the progression of the seasons has influenced the north-south distributions of physical and biological conditions across the shelf.

The attached map of the near-surface water temperatures measured by the Healy's underway system, which pumps water from a depth of 8 meters below the surface, shows the warmer water (yellow) offshore and the cooler water (blue) onshore, separated by a band of intermediate water temperature (see other data track maps). Notice the fronts, highlighted by drastic changes in water temperature, we have traversed during the cruise. Because these frontal zones may be ecologically important areas where organisms concentrate and localized productivity is enhanced, researchers are very interested in mapping their extent and dynamics.

During the three weeks we have been on the Healy, we have completed 154 stations and consumed about 210 gallons of milk. Both the excitement of scientific discoveries, and our friends at the "Java shack" keep us going strong. Caffeine (via coffee, tea and chocolate) has proven critical to keep the

science efforts underway. The weather, which has been superb for the last few days, has allowed us to make great progress and to cover lots of ground. The last couple of days we have experienced high atmospheric pressure (1009 millibars) and low wind speeds (below 10 knots). The sunshine enhances the contrast between the ice cakes and the dark water, turning the sea into a black and white checkerboard.

We are occupying the southern-most (offshore) station along a line spanning from the shallow (< 70 m) ice-covered shelf to the deep waters (> 3000 m) off the continental slope. We have encountered new species in this deep-water region,

including oceanic seabirds (e.g., storm-petrels) and large whales (e.g., tall and skinny blows sighted off in the horizon, likely from fin whales). Later on in the summer, we would expect mottled petrels from New Zealand and sperm whales

We will remain at this station for about 8 hours, completing very deep multi-core drops and a CTD cast to 3300 m, equivalent to 331 atmospheres (atm) of pressure. For every ten meters of water depth, the pressure increases by one atmosphere, plus we have to add the weight of the atmosphere above the sea surface. These deep casts provide a perfect opportunity for an oceanographic tradition. We have decorated styrofoam cups with colorful designs. They will be attached to the CTD and sent down to depth, causing them to compress and shrink to a minuscule size with the pressure. An 8 ounce cup looks like a 1-ounce espresso shot (or smaller) once it has been to depth/pressure.

Today we transited towards the southwest, heading along the outbound leg of the "N" pattern in search for ice edge phytoplankton blooms. We sailed through the broken pack and an area of lighter sea ice cover (20-40% of the sea surface) littered with ribbon and spotted seals resting on ice cakes. Even the scientists are coming out on deck to enjoy the Sun and the (relatively) warm air (go to today's photos to see a variety of basking mammals).

In the early afternoon, the underway data recording system onboard the Healy documented a high-chlorophyll patch indicative of elevated localized productivity. We abandoned the pre-determined transect and engaged in a fine-scale sampling grid to document the spatial extent of this high productivity area. During the adaptive sampling phase of the cruise, we will take advantage of these opportunities to sample areas of enhanced biological activity as they become apparent to us. Because of the cloud cover, we have not been able to obtain remote sensing (satellite) imagery to assess chlorophyll concentrations in open water areas of the Bering Sea. However, if we continue having sunny days like today, we may obtain some good satellite images of phytoplankton blooms in the open water areas of the shelf and the slope. In particular, the area of the "green belt" (article, image)and the slope front may support high chlorophyll concentrations.

As part of our attempt to identify oceanographically and ecologically interesting areas to sample, we have relied on satellite imagery to assess how fast the sea ice is retreating northward in the Bering Sea. This image illustrates the sea ice melt back we have witnessed during the last two weeks, by comparing sea ice extent during an early period (April 15-17) and a later period (April 28-30). Remember how to interpret these images: areas covered by sea ice appear "rough", while open water areas appear "smooth". Notice the large area of open water northwest of St. Lawrence Island and off Russia, which is apparent in the second mage but is not visible in the first picture.

Researchers rely on longer-term data (also called climatologies) to assess whether the current conditions are above or below the average. One of the metrics we use to gauge whether sea ice conditions are abnormal for any given year is the comparison of monthly data from year-to-year (see maps of ice cover in April from 1990-2005). Understanding how this year-to-year variability in the physical oceanography affects the ecosystem structure of the Bering Sea is a critical component of the BEST program

The Healy has started a series of 25 CTD/net stations along three lines arranged in a zipper-like pattern (like the mirror image of a capital "N") zig-zagging across the shelf. The onshore end of the

lines is anchored on the ice-covered section of the shelf (depth < 70 m) and the offshore end is over the slope (depth > 2000 m). By repeatedly crossing the transition between the ice pack and the open water, we will be able to compare the hydrography (water properties), the productivity (in the water column and the mud) and the animal distributions (zooplankton, fish, seals, birds) across different ice domains. Last year, this marginal ice zone proved to be an area of seabird (murres) and whale (rorquals) concentrations. So far, we have only encountered two minke whales in the area.

As the sea ice melts and retreats, we expect this marginal ice zone to migrate northwards. However, the prevalent wind patterns will greatly influence the fate of the sea ice in the next two weeks. Winds from the north should push the sea ice south, spreading the broken pack into a series of thin bands and strips. Conversely, winds from the south should push the ice northwards, causing it to pile up. In addition to the prevailing winds, changes in the air temperature may speed up the spring melt-back.

As we approached the end of the first line, southwest of Nunivak Island, we sighted large pieces of sea ice stained with dark bands, unlike the more orange-looking patches and bands of sea ice algae we had seen earlier in the cruise. Carleton Ray confirmed that these dark bands were sediments entrained in the sea ice when it froze. The presence of these terrigenous (or land) signatures are evidence that some of this "fast ice" formed on the shore and drifted offshore.

During our northward transit, the physical oceanographers onboard (Carol Ladd, Nancy Kachel and Dylan Righi) deployed an Argos drifter. This oceanographic instrument consists of two parts: a transmitter encased in a float, tethered to a long tubular drogue which sinks to depth (in our case 40 meters). The drogue portion is referred to as "holey sock". These drifters provide oceanographers data on the movements of the near-surface part of the water column, which are then used to infer advection (lateral movement) of water masses and weakly-swimming organisms, like fish and crab larvae. [movie of drifter launch, 10MB, Quicktime]

In the evening, we searched for a large floe sturdy enough to deploy the ice coring team. The team went on the ice via the "man basket" and successfully completed the third ice coring station of the cruise.

Today is a major turn-over day at the Healy: the end of the fist leg of the cruise and the start of the second. Several scientists are leaving the ship and being replaced by a new batch, and the personnel transfer is taking place in St. Paul. Scientists, luggage and equipment will be shuttled from the Healy to the local airport via helicopter or small boat, depending on the weather conditions. To ensure

these personnel exchanges go smoothly, it is critical that departing and arriving scientists have some time to discuss any unexpected issues or problems that may have arisen during the cruise. Because lunch provides a great opportunity for these discussions, the Healy's mess deck is filled to the brim and buzzing with activity.

In addition to the personnel exchange, we have arranged some activities with the St. Paul school. On Friday 27th a group of incoming NOAA scientists, lead by oceanographer Carol Ladd, gave two school presentations at the school. On Saturday morning, the two teachers onboard (Maggie and Robyn) were dropped off in the early morning for a day of activities with local teachers and kids at St. Paul. Three people from St. Paul (a high school student equipped with recording equipment, a teacher and a community leader) came onboard the Healy for a tour of the ship and the science spaces. The activities at the school included a demonstration by Aleut Dancers and a series of fun educational stations dealing with the ecosystems of the Bering Sea.

Weather conditions continued to deteriorate throughout the morning and early afternoon, and by the time the Healy left St. Paul the wind was blowing up to 35-40 knots. U pon our departure, we started

heading across the shelf and towards the ice-covered water to the north of us. After the large-scale survey of the shelf completed during the first leg of the cruise, the second leg will focus on sampling specific features of interest in more detail. Re-sampling the area of high chlorophyll concentrations we encountered over the shelf-break west of St. Matthew island, revisiting the stations in Bristol Bay, and working along the edge of the sea ice are top priorities. As we enter this "adaptive sampling" phase of the cruise, real-time information on sea ice conditions from satellites and helicopter flights will become increasingly important to locate and track interesting features for sampling.

Friday April 27th began with a boat brief. The Healy was stationed off Zapadni Bay, in the south end of St. George Island and we had a ten o'clock appointment on the beach. Nine scientists and two Coast Guard representatives (Stephen Elliott and David Forcucci) suited up with immersion suits and helmets, and boarded two inflatable small boats on the Healy's main deck. After being lowered

approximately 45 feet one at a time, we began cruising towards the snow-covered shore. Flocks of crested auklets, small white and black diving seabirds, lifted off the water in front of the boat as cormorants sped by. Our guests met us at the dock with a school bus. We peeled out immersion suits off and rode the bus into town, passing by the green Russian Orthodox Church, the seal plant, and the kittiwake cliffs. There are no trees anywhere in sight. Despite the bright sun in the sky, it is still winter in St. George: the school's outdoor basketball courts are covered in snow and there are no puffins around.

We are greeted by Carol, Carl, Miriam and Lori - the teachers at the St. George School - and nineteen curious kids. "People bingo" broke the ice and gave us a chance to get to learn some important details about each other: Carleton has hugged a walrus before, Lee has gone whaling before, Maggie does not like chocolate, Ned has drilled a whole in the ice before, David is wearing black socks. In St. George, we did not need the Healy to break the ice, just some smiles. After the ice-breaker, we split up into three groups. The middle school and elementary school ran a course of activities: they learned about whaling in Point Hope with Lee, tried drawing a humpback whale, made an albatross flier, put on an immersion suit in record time, learned about food webs, and tried some of the goodies Maggie brought from Hawaii. In the meantime, Robyn Staup and David Shull gave the high school kids a virtual tour of the Healy and chatted about what being a scientist is all about. Other scientists went with Rodney on a guided tour of the seal plant, where the blubber and the pelts from harvested fur seals are processed.

After lunch, Ray Sambrotto (cruise chief scientist), David Hyrenbach (BEST Project Office) and Ned

Cokelet (from NOAA's Pacific Marine Environmental Lab) gave a presentation - open to the community at large - about the Bering Ecosystem Study (BEST) and the objectives and results of this cruise. After a lively question and answer session, it was time to head back to the dock. The two inflatable boats (Healy 2 and Healy 3) picked us up at 3 pm. We brought along four high school students and teachers back with us to the Healy for a tour and dinner together. The day ended with Captain Lindstrom presenting our visitors from St. George with a plaque to commemorate their visit. It has been just a few intense hours in St. George, but we have learned a lot and had a blast.

As soon as our visitors disembarked (around 7 pm) we are underway again. We completed several night-time CTD and plankton stations around St. George and St. Paul, where we will exchange a batch of ten scientists with fresh replacements, about one quarter of the science party onboard the Healy. Come back to find about our visit to St. Paul and to meet some of the new faces in the ship.

Albatross!!
The Healy is finishing a line of stations south of the Pribilof Islands, before the visits to St. George island (April 27th) and St. Paul island (April 28th). This line runs across the shelf and into deep water beyond the continental slope (over 2000 m in depth). During the transit across the shelf-break (200m depth contour), we encountered an area of high seabird densities. Mixed in with countless northern

fulmars and murres, we sighted a Laysan albatross (Phoebastria immutabilis) soaring effortlessly over the waves. This large tubenose bird (order Procellariiformes), with a weight of approximately 3 kilograms (6.6 pounds) and a wing-span of 1.8 meters (6 feet), breeds in Hawaii and off Baja California and ranges across the entire North Pacific and into the Bering Sea. Laysan albatross chicks are born in late January/early February and fledge by late June. Their parents commute from Hawaii to the waters of the North Pacific Transition Domain and the Aleutians during round-trips of up to 28 days. Even though we have no way to tell with certainty the status (breeding/ non-breeding) or the provenance (central Pacific or Mexican breeding colonies) of this albatross, we fancy this bird heading back to the Northwest Hawaiian Islands, where a hungry chick awaits a meal of energy-rich stomach oil from squid and fish. Researchers have documented these provisioning voyages from tropical waters (SST > 25 degrees C) to the Bering Sea (SST< 12 degrees C) using satellite tracking (to view albatross tracks: las.pfeg.noaa.gov/TOPP_recent/index.html).

When we reached the southern-most station along this line in water over 2300 m deep, the Laysan albatross approached the boat with a companion; A larger, all-dark bird with a massive pink "bubble-gum" bill: a juvenile Short-tailed Albatross (Phoebastria albatrus). Everybody in the bridge jumped for joy. This endangered albatross, with an estimated world population of approximately

1800 birds, breeds south of Japan in Torishima (Izu Islands) and Minami Kojima (Senkaku Islands). In spite of its recovery from the brink of extinction in 1949, this species remains well below its historical abundance, an estimated population of above 1 million birds at the beginning of the 20th century. Short-tailed albatross adults and juveniles disperse from the breeding colonies in the western Pacific to the Bering Sea, where they concentrate along the shelf-break and the Aleutian passes (Amchitka, Seguam, Buldir). Satellite tracking studies have followed the migrations of these birds into the Bering Sea and all the way to the West Coast of North America (www.wfu.edu/biology/albatross/shorttail/shorttail2.htm).

These albatross sightings off the Pribilof Islands highlight the importance of the Bering Sea as a foraging ground and a nursery for many far-ranging species, including marine birds and mammals.

Two spotted seals were tagged yesterday by a team of biologists lead by Michael Cameron from NOAA's National Marine Mammal Laboratory (NMML). Already they have transmitted several messages to the satellites overhead. The researchers onboard the Healy can check the status of their tags in

real-time via the internet to ensure the tags are working properly. Thereafter, the researchers will receive periodic email messages with the location information (every 24-72 hours).

Deploying the tags requires capturing and handling the animals in the wild, often in challenging conditions. The researchers disembark the vessel and approach the seals either by small boat or by foot, depending on the amount of sea ice and open water. They approach seals resting on large floes, crawling on the sea ice with great stealth in an attempt to block the animals' escape route into open water. A very different strategy is required when approaching a seal on a small floe surrounded by open water. Three inflatable boats converge onto the seal from opposite directions, disorienting the surrounded animal. All the researchers need is a brief hesitation, so they can jump onto the floe and net the seal. In addition to deploying the tag, the biologists take

blood and skin samples for population genetics and health studies. Because the entire operation lasts about an hour, the researchers often tag multiple animals at once. The longevity of the tags depends on the battery life-span and the attachment method: those glued onto the fur are shed when the animals molt in summer, and those attached to the flippers eventually fall off after 1-2 years (more seal information).

Seal biologists deploy three basic types of satellite tags, each capable of providing time-stamped location information and ancillary data on the quality (error) of the satellite fixes. In addition to location data, these Argos-linked (satellite) tags provide other valuable sensor information:

These novel tags record and transmit information about the properties of the water the seals swim through during their dives. In addition to these Argos-linked transmitters, novel GPS (Global Positioning System) tags provide very detailed data on animal movements (with errors in the order of tens to hundreds of meters rather than kilometers for the Argos tags) at equally-spaced time intervals. These developments in wildlife tracking technology have allowed researchers to follow the movements and migrations of far-ranging animals, including seals and cetaceans. Oceanographers also use these Argos treansmitters to learn about surface currents by following the movements of drifting buoys (see a 2007 movie of satellite-tracked drifters as they move with currents).

We have been on this cruise for two weeks, and the Healy is really becoming like our second home. In these last two weeks we have completed 120 stations and consumed 120 pounds (55 kilograms) of bacon. We suspect this is a mere correlation without causation, but will investigate further during the rest of the cruise.

After completing an east-west transect of 20 stations from the slope (2700 m deep) to the inner shelf (40 m deep), the Healy took a right-hand turn and began heading to the southwest. Before we stop in the Pribilof Islands on April 27-28 for a visit and personnel exchange, we will re-occupy a series of hydrographic stations sampled in the 1970s and 1980s. By repeatedly visiting these stations, researchers will be able to compare the physical and biological conditions in the water column across several decades. This long-term perspective is critical to investigate ecosystem changes in the Bering Sea shelf.

To celebrate our second week onboard, we had a science-filled day with three successful on-ice activities. In addition to completing a morning ice coring station to sample iron, nutrients and sea ice algae, an inter-disciplinary team of researchers set up an experiment to quantify the level of primary production from the sea ice algae. The underway data collected thus far during the cruise have identified some interesting patterns, suggesting there may be exchange of oxygen between the sea ice algae and the water column beneath.

To test this hypothesis, researchers set up an experiment in the morning, before the sea ice algae had been exposed to high levels of sunlight. They drilled several cores through the ice pack and measured the oxygen saturation in the surface waters immediately below the ice. The team returned to the same site with the helicopter to re-sample the ice in the early afternoon, once the primary producers had a chance to create new oxygen via photosynthesis. The helicopter proved invaluable for completing this experiment. It allowed the Healy to steam ahead and continue making progress towards the east, while the experiment ran its course. Later that evening, the seal team deployed to the ice and managed to tag two spotted seals with satellite-tracking transmitters. These tags, with a life-span exceeding one year, will allow the researchers to track the movements of these animals over the spring, summer, fall, and winter. Check back tomorrow for some pictures of the seal tagging operation.

Science goes on as we continue east along the Nunivak Island line. After crossing the shelf break (200 m depth contour), we encountered an area of acoustic backscatter from ecosounders. This signal is attributed to fish, probably juvenile walleye pollock, by virtue of the dimensions of the patches and their depth in the water column.

The same way that the microwaves from the RadarSat satellite can detect the amount and type of sea ice through clouds, we use acoustics to peer down into the water column in search of fish and zooplankton. Basically, the ship sends a pulse of sound into the water column at two different frequencies. The low frequency (38 kilohertz) is used to detect fish (larger targets) and the higher frequency (120 kilohertz) is used to detect smaller targets, mainly euphausiids (large zooplankton about 20-30 millimeters or 1 inch long). Some of the energy from this pulse bounces off submerged targets and is received/detected back on the ship (more acoustics information).

Once analyzed, these data provide a two-dimensional picture of the vertical and horizontal distribution of the back-scattering organisms in the water column. Check out the picture of 38 kilohertz backscatter provided by Alex De Robertis, showing the vertical migration of a layer of fish in the evening. Focus on the blue-green layer shoaling from left (earlier) to right (later). These fish are moving up into the water column in the evening. During the day, the fish are close to the bottom of the shelf (about 125 m or 375 feet). In the early evening, at about 7 pm, they begin to move up into the water column and are often found as a layer about 75 m (225 feet) deep. By approximately 10 pm, the layer starts to break up as fish start moving into the upper part of the water column. By midnight, the fish are widely scattered throughout the water column. Many fish and zooplankton species undergo similar daily vertical migrations to feed in the upper water column at night, returning to depth during the day. The pollock's 375-feet vertical migration on the Bering Sea shelf is far better than most people's commute. This is when we realize one major advantage of living onboard the Healy: our Monday morning commute is less than 420 feet (the length of the ship).

Mud is the flavor of the Day: We started this overcast and windy Sunday in the most offshore station of the Nunivak Island line, in water approximately 2700 m deep and with no ice in sight. Because the CTD and multi-corer casts are going much deeper in the water column (approximately 35-40 times deeper than the shallow stations we have completed on the shelf), the stations take considerably longer. But the rewards of these long casts are even more precious: mud from the bottom of the ocean, almost 1.5 miles deep. The multi-corer is equipped with eight cores and a niskin bottle, used to collect water samples at depth.

As soon as the mud is onboard, a team of chemical oceanographers under the guidance of David Shull and Allan Devol gets to work. They unlock the core and use their trusty "core extractor" (also affectionately known as "Mr. Stumpy") to push the column of mud upwards through the transparent core tube until they reach the mud-water interface. A sharp water-mud interface, without any murky water and foamy sediment is the tell-tale sign of a good core. The sample is rendered useless whenever the sediment is resuspended because the vertical resolution of the samples is lost in the process

After selecting the good cores and measuring the height of each column of mud, the researchers slice the mud into thin layers (5 cm at first and 10 cm later on as they dig deeper), and store their greenish, slippery samples into baggies and plastic tubes. The researchers

will use a centrifuge to separate the pore water from the mud, so they can analyze each component separately. By looking at the isotopic signatures in the mud and the water, these researchers are gaining insights into the degree of nutrient recycling that takes place in the sediments. This is a critical and poorly understood aspect of the nutrient cycle of the Bering Sea, with important implications for the productivity of this ecosystem.

During the day we have traveled east into progressively shallower water. Along the way we have completed several more CTDs, multi-corer drops, and net tows. In the early afternoon, we encountered the first signs of sea ice, crossing a few scattered bands of ground up debris (brash) first and small rectangular pieces (broken pack) later. As the percent of the sea surface covered by sea ice increases, we run into larger and larger ice cakes a few meters wide. The glaucous gulls replace the fulmars as the dominant birds in this marginal ice zone. We are back into seal territory once again.

It is Saturday once again: cleaning in the morning and a movie in the evening break the routine onboard the Healy. Yet, science goes on day and night. See the beautiful photographs from the night crew for insights into what night-time activities look like. Nocturnal navigation in heavy ice is aided by large spotlights mounted on the bow of the ship. In spite of the warm clothing

and the flood lights, working on the aft deck under he moon and stars can be very chilly and phantasmagorical. We are in full gear: we have completed 89 stations already and are making good progress.

Yesterday evening we came within a few miles of the U.S.-Russia border, before taking a right-hand turn to start a 172 nautical mile (318 kilometer) transit to the south-west. On the way from the Saint Lawrence to the Nunivak transects, we traversed an area of ice pack broken up by the swell and storms. This transect took us through different bands of sea ice, each with a different fauna. Solitary glaucous gulls and ribbon seals basking on the broken pack, were replaced by dense flocks of murres (diving seabirds) foraging amidst ice floes farther south. When we eventually reached the open water, a pod of orcas and thousands of northern fulmars welcomed us.

This evening we are off the shelf, in water approximately 2700 m deep (almost one mile and a half). There is no ice insight (see the aloft camera snapshots) and we can feel the swell rolling by below us. For the first time during this cruise it feels like we are on a ship since the wave action is not dampened by ice. We will spend approximately ten hours at this station completing a CTD, net tows, a deployment of the "iron vane" and two multi-corer drops. This deep water station is critical because it provides researchers with an offshore sample, representative of the conditions of the basin domain. Different organisms inhabit the deep-water areas of the Bering Sea. The archetypical seabird in this offshore area is the forked-tailed storm-petrel, an oceanic species the size of a swallow which forages at the surface on zooplankton and larval fish. Tomorrow, we will sail east back onto the shelf and into the ice. We expect to find birds and whales foraging along the shelf-break (200 m depth contour). Stay tuned.

The Healy has been heading west (towards deeper water) along the SLO line for the last two days. During this transect, we have traversed alternating bands of frozen leads and jumbled up broken pack. At times, we encounter open pools with small diving seabirds (black guillemots) and

basking pinnipeds (mostly bearded seals). The splintering sheets of newly-formed ice are often littered with the breathing holes of seals. Check out the photos of some of the frozen lead punctured by seal holes. This icescape resembles a mud flat in the bright sunshine; seal breathing holes instead of fiddler crabs burrows.

For a large-scale view of the sea ice conditions around us, look at the fine resolution (about 100 meters) imagery from the RadarSat satellite. This imagery does not provide a metric of ice cover (%) or ice thickness directly, but it tells us about the roughness of the ocean surface. This provides an indication of the intensity of wind over

open water and of the presence and type of ice. For example, the smooth (dark) area south of St. Lawrence Island suggests this is open water or newly-formed ice. Conversely, the rough-looking patches of clear and dark bands to the east and west of the island denote broken and jumbled pack ice. Rougher surfaces appear clearer because more of the radar energy bounces back towards the sensor on the satellite overhead. Smooth surfaces bounce the incoming energy away from the satellite overhead.

We have encountered many small groups of walruses (25-50 animals at a time) in the last two days. Walrus are larger, reaching up to 4000 pounds (about 2000 kilograms) in weight and 9 feet (3 meters) in length. Carleton Ray, a walrus expert onboard, has seen new-born walrus pups on the ice during this cruise, even though we are about one month before the peak birthing time for these animals. Walrus breed in May and their gestation lasts 12 months, after an initial two-month delayed implantation of the fertilized egg. Because, the entire reproductive cycle of the

Yesterday evening we completed the second ice coring station of the cruise at the shoreward (shallow) end of the SLO line. Approximately eight more of these ice coring events will take place during the remainder of the cruise. The conditions were ideal: wind was down to less than 5 knots and the sea ice was thick. We were sailing through heavy pack ice interspersed with high (6-9 feet or 2-3 meter) ice ridges. These ridges have sub-surface keels (think of them as roots, if you will), which are at least twice as thick as the height of the ice piled above the surface (also referred to as the sail). In fact, because there is so much submerged ice, the Healy's wake fills up with ice debris stained brown by the ice algae.

Two groups of researchers equipped with mustang suits and bunny boots were lowered onto the ice

using the "man basket", while a rescue diver stood by in case anyone fell into the frigid water (April 18 photo, this page). NOAA scientists Ned Cokelet, Dylan Righi and Jeff Napp drilled a series of ice cores and augur wells to obtain snow, ice and brine (pockets of salty water embedded within the ice) and water samples. While the sea water and sea ice have a salinity of 3-5 and 31-32 PSU (practical salinity units), respectively, the brine can reach salinities of 30-40 units. Physical oceanographers will use this information to understand how melting of sea ice influences the physical structure of the water column. The cores are retrieved and sliced into 10 cm slices using a hand-held pruning saw, just like you would cut a small tree. The core is photographed, and temperature measurements are taken for each 10cm slice before returning to the ship lab where it is melted and analyzed for the content of nutrients, salt, and phytoplankton. Researchers also take light measurements above and under the ice with a PAR sensor (Photosynthetically Active Radiation), to determine how much light is available for use by photosynthetic organisms living within and below the ice. The last step involves incubating the algae retrieved from the ice to measure the rate of primary production (the amount of carbon fixed via

photosynthesis per unit time). These data provide researchers with a sense of how productivity is taking place within the ice. What remains unknown is the fate of these primary producers once the ice melts. Do they seed the water column and stimulate the open water bloom? Do they perish and sink to the bottom as the physical conditions around them change drastically?

A second group of researchers from the University of Alaska at Fairbanks, Rob Rember and Ana Aguilar-Islas, sampled the snow, ice and water in the leads for traces of iron using "clean instruments" to avoid contaminating the samples. These researchers drilled a hole through the ice and sampled the water beneath by lowering a hose several meters into the water. By comparing the measurements from the open water and the ice cores, researchers will develop a comprehensive picture of the interactions between the sea ice and the water column. This understanding is critical to anticipate ecosystem-level responses to changes in the amount of sea ice and the timing of the spring-time melt. These are some of most pressing research questions that motivate the BEST program.

Late on in the evening, we started the fourth phase of the cruise. We began traveling west along the Saint Lawrence line (SLO), sampling a series of 16 stations separated by 10 nautical miles (18 kilometers). We also run a 30 nm (3 station) transect towards St. Lawrence Island, to sample an area of newly-formed sea ice downstream from the polynya. Come back tomorrow to check out photos of the walrus we encountered in this area.

A storm blew over us yesterday, and today we are back under sunny skies. Winds have decreased from yesterday's 40-45 knots to 20-25 knots this morning, and 0-5 knots this evening. The barometer jumped up from 996 to 1008 millibars, suggesting we are under the influence of an anticyclone (a high pressure system). To see maps of the weather conditions we are experiencing, please visit this NOAA Web Site showing GOES Satellite image and also the UW-Atmospheric Sciences MM5 forecast (model data for wind, sea-level pressure and air temperature for the next few days).

After traveling due east all day, we reached the shoreward end of the Saint Lawrence line (SLO) in the afternoon. At the end of this transect, we encountered fairly tall ice ridges (3-6 feet or 1-2 meters high). This icescape looks and sounds very different from what we traversed two days ago when we sailed through the newly-made ice over the frozen polynya. Thick ice scrapes against the Healy's hull, making noises akin to going through a car wash during an earthquake.

Even though we have had superb visibility all day, observers on the bridge can only look about 5-10 kilometers ahead of the ship with binoculars. To figure out what lies farther ahead, we rely on satellite images and helicopter surveys. These eyes in the sky provide a larger-scale perspective of sea ice conditions, which allows us to adapt our cruise track to sample interesting features.

Helicopter operations resumed today, once the winds dropped below 25 knots. The chief scientist, Ray Sambrotto from the Lamont-Doherty Observatory, and Carleton Ray, a sea ice expert from the University of Virginia, flew a reconnaissance (recon) mission in the afternoon. They ventured approximately 90 miles east and west of the Healy's position, and made their way back south towards the Pribilof Islands. They inspected the polynya south of St. Lawrence Island, and reported the first sightings of two emblematic polar species: a polar bear and a beluga whale!!!

In the meantime, everyone on the Healy enjoyed an evening in the sun. Check back tomorrow to learn what this diver is doing on the ice.

Week in Review: After a week at sea, we have sampled 66 stations (about one third of 187 stations planned) and have completed the first three phases of the cruise:

the survey of Unimak Pass to investigate the exchange of water between the Bering Sea and the Gulf of Alaska,
sampling in the vicinity of mooring M2 and Bristol Bay early in the season, and
the fine-scale (10 nautical mile, 18 kilometer) survey of the middle shelf along the 70-meter isobath.

Next we will head east, towards the shallower inner shelf (40 m depth). Because the currents and wind concentrate the sea ice in this area east of St. Matthew Island, we expect to encounter thick layers (up to 2-3 meters thick) of jumbled pack. We will continue sailing eastward until our advance is slowed down by the heavy ice.

During this first week we have had a chance to try out all of the components of the cruise. We have sampled the water column using nets and CTDs, and have taken mud samples using the multi-corer. The first data plots showing the distributions of physical, chemical and biological properties along our survey track (salinity, temperature, oxygen, fluorescence) are already available on this site. Maggie Prevenas and Robyn Staup from PolarTREC have also been recording ice conditions every two hours, using a standardized electronic log formm the NOAA Observers' Guide to Sea Ice (pdf), and hourly digital photographs from an aloft camera on the Healy.

In addition to the ship operations, we have deployed a seal tagging team and an ice coring team on the ice, and have undertaken helicopter surveys of seal and walrus distributions over a wide area of the Bering Sea shelf. A camera mounted on the helicopter takes a photograph every 2 seconds, providing researchers with a continuous record of the ice conditions and the animals under the flight path. For an example of what this looks like, we show the collage of a Healy over-flight provided by Josh London from NOAA (photo below, click for larger). This image was obtained by sticking together 7 consecutive images taken over the span of 14 seconds.

During this first week of the cruise we have consumed a staggering 1890 eggs and countless gallons of coffee. However, it has become apparent what has been this week's most critical tool at our disposal: the Healy's bow. Crushing the ice out of the way and allowing us to sample these ice-covered regions of the shelf.

** USCGC Healy: Monday, April 16, 2007 (see images for this day)

After slowly crunching our way through thick ice (up to 15 inches thick) around the southeastern end of St. Matthew Island last night, we reached the area of the polynya this morning. On April 14th satellite imagery indicated a large pocket of open water (about 20 nm, or 36 km wide) to the southwest of the island. When we arrived on the 16th (today), it was not there anymore. Instead, we encountered a thin (3 to 6 inches, or 7.5 to 15 cm) layer of greyish ice with a myriad ripples and meanders frozen solid by the cold air that we have experienced these last few days. As we sail through this newly-formed ice, the Healy pushes thin layers over each other creating surreal zipper-like structures; like the massive scars on Frankenstein's head. As these layers slide over each other ahead of the ship, the ice thickens and changes color from grey to white. Large ice flakes, resembling giant fish scales, float behind the Healy. This highway of open water will close back up once we have gone through, given the frigid (-8 to -10 degrees C.) air temperature and the well-mixed water column, top to bottom.

Uglat mark on ice shows recent walrus presence. photo by D.Hyrenbach.

We completed four CTD stations within the frozen polynya, two of them along an onshore-offshore transect from St. Matthew Island. Having replicate samples in this region will be critical to compare the current conditions with those during future visits later on this spring and in coming years. The transect across this area yielded few seabirds, mostly murres and guillemots diving in the open water pools and leads amidst this vast frozen seascape. As we approached the broken pack (thicker ice) on the western side of the polynya, we encountered several bearded seals. Some sit on the ice, others roll around in open water pools, and others curiously poke their heads through small openings in the ice. There have been no walrus sightings today, but we can tell they are around. A brown stain on an ice floe is evidence that a well-fed walrus was in the neighborhood (see photo of the unmistakable "uglat" or walrus ice). Perhaps we will see them around the corner from St. Matthew, as we transit along the 70-m isobath northwards towards St. Lawrence Island.

As we enter the densely ice-covered areas of the shelf, we have started on-ice operations. Three teams of researchers will be descending onto the pack ice by helicopter, basket, and small boat to

Coast Guard polar bear watch during on-ice operations.

The Coast Guard, on polar bear watch during ice operations. photo by E.Davenport

sample different aspects of the chemistry and ecology of the sea ice. A team of NOAA biological and physical oceanographers lead by Ned Cokelet take cores ofr ice and algae samples within and under the sea ice. Chemical oceanographers from University of Alaska at Fairbanks, lead by Rob Rember, will sample iron concentrations in the snow and ice to complement the water samples collected with the vane. A team of NOAA wildlife biologists, led by Michael Cameron, will capture and track ice seals using the Argos satellite tracking system. The first trip onto the ice took place yesterday evening. A four-person seal team boarded the "man basket" on the helicopter deck and was lowered with a crane onto the ice. It is just like a two storey elevator ride, except for the mustang suits, bunny boots, and armed guard to keep an eye on polar bears potentially lurking by. Needless to say, on-ice operations are a great source of entertainment for everyone onboard the Healy. Check out today's photos for a sample.

** USCGC Healy: Sunday, April 15, 2007 (see images for this day)

What a difference a day makes. Today we are in an area of heavy ice concentrations (70-90%) south of St. Matthew Island (approx. 172.5W, 60.5N, see map), sailing through a matrix of floes extending all the way to the horizon in every direction around us. When we break the ice ahead, the ice algae under the snow and the ice spill into the sea, turning the dark water in the opening leads a brownish tint. The water is thick with algae too, and the cod-end of the nets yield a soup of zooplankton and phytoplankton resembling orange-mango tang.

We are making our way towards the northwest, and will reach a polynya (an area of open water amid ice) southwest of St. Matthew Island early tomorrow morning. This area may contain large numbers of migrating seabirds waiting for the sea ice to open up to continue their northward migration, as well as locally-breeding species from St. Matthew Island foraging before the breeding seasons starts.


Grease ice. Open water upper left of left photo; stacking up on right photo. photos by D. Hyrenbach.

The barometer continues to climb, and we have encountered higher wind speeds (10-20 knots) and considerably cooler air (-8 degrees C.) and sea surface water (-1.6 degrees C.). New ice is forming around us, with the oily sheen at the sea surface characteristic of the "grease ice" covering the open water pools amidst the floes (see photos). These cold conditions are quite challenging for both the equipment and the researchers. Everything is freezing up on the decks: the salt water hoses required for rinsing zooplankton samples, the incubators for primary production experiments, the Seacat (a CTD sensor that is attached to nets to sample the temperature and salinity of the water column), and even the CTD bottles and nozzles. Yet, the researchers complete station after station, day and night, armored with cold weather gear: mustang suits, comfy hats and thick gloves. Add to shopping list for next year: heat guns to thaw CTD bottles.

Today's conditions are drastically different from what we witnessed yesterday. There are no foraging murres or gulls following the ship through this heavily iced area. The only seabirds we have encountered are black guillemots diving in the open water leads amidst the ice floes. On the other hand, this seems to be prime spotted and ringed seal territory. We have seen several mothers with their pups on the sea ice. However, there have been no walruses in sight. We hope to encounter them farther north.

** USCGC Healy: Saturday, April 14, 2007 (see images for this day)

Saturday is a special day on the Healy: we cleaned in the morning and went to the movies in the evening. The weekly cleaning up duties entail tidying our rooms, emptying the trash cans, and sweeping and vacuuming all the common spaces. Later on, we spent the evening watching 007's "Casino Royale" in the helicopter hangar. In the meantime, we continue to work our shifts and make our way to the northwest along the 70-m isobath, sampling a series of closely-spaced stations with CTDs and bongo nets along the way. With one station every hour, day and night, the number of samples is rapidly building up

Map of ice cover in our work areas.

After two brief encounters with the marginal ice zone farther south, we have entered an area of heavy ice. As the satellite imagery suggested (see map) our track along the 70-m isobath took us into areas of heavier ice concentration. We expect the proportion of the sea surface covered by ice to range between 30 to 60% tomorrow (Sunday) and from 70 to 90% the day after (Monday). Nevertheless, because the wind and currents move and redistribute the ice, they can create open water areas (in places where diverging ice separates) and denser ice concentrations (in places where converging ice comes together). Because of these ever-changing ice conditions, the satellite images give us only a rough indication of what to expect.

For instance, today we encountered a very heterogeneous seascape of alternating bands of sea ice and open water. We have encountered ice cakes, sharp-edged pieces ranging in length from approximately 5-25 meters (15-75 feet) and pancakes (smaller round-edged pieces). At times, we were surrounded by heavy ice, with concentrations of up to 90%. Yet, the Healy's bow easily opens a path through the ice sailing at 10 knots, leaving behind an open water highway that slowly closes back up.

We have encountered new organisms as we make our way into the ice, including spotted and ribbon seals. The marine mammal researchers have gone airborne to survey seal distributions from the air. Using a helicopter, they venture away from the ship and cover large swaths of territory photographing the sea ice and recording sightings on either side of their flight track. During these flights, which take 2-3 hours, the Healy continues conducting oceanographic stations and sailing to the northwest.

The first sightings of walruses and polar seabirds (like the ivory gull) provide hints of what we might encounter farther north. Today we also witnessed several large flocks (thousands) of murres rafting and diving by the ice edge. Alex de Robertis from NOAA documented a dense subsurface layer of fish in the same area using acoustic measurements. By integrating data from predator and prey distributions with information on water properties and sea ice conditions, this cruise will help us determine what physical and biological processes affect the distributions of the organisms we are encountering. For example, do seabirds eat fish and zooplankton available closer to the surface at sea ice edges? We had pizza and watched a movie. Listening to the rumbling noise of the bow crushing the ice, wise words come to mind: "mixed not stirred".

** USCGC Healy: Friday, April 13, 2007 (see images for this day)

No sunshine today for us. It has been snowing intermittently most of the day. The air temperature has dropped to -2.7°C and the water is also very cold (-0.4°C). However, the weather has been superb: flat seas (half a meter wind waves and no swells), low wind (5 - 15 knots) and great visibility. The barometer is at 1007.5 millibars and has been going up for the last two days, so we have no complaints. In spite of the grey day everyone went up on the bridge to check out the sea ice up close when we broke through a couple of bands of ice cakes, ranging from 1-25 meters in size.

The Healy continues making its way to the north-west along the 70-m isobath. We complete stations, with 10 nm (18 km) spacing, day and night. Every 45 minutes we reach a new station and the scientists jump into action. We have completed 25 stations already out of the planned 187 stations. CTDs are deployed at every station to ensure we have information on the water column structure (salinity / temperature) and the fluorescence (a metric for chlorophyll concentration). We also sample zooplankton at every other station (every 36 km) and have completed several multi-corer drops to sample the mud at the bottom of the shelf.

benthic invertebrates. photo by D.Hyrenbach.

The multi-corer retrieves mud and water samples from the seafloor-water interface, which provide clues about the magnitude of nutrient and gas exchanges between the sediments and the water above. These samples also retrieve interesting creatures, including a broad array of invertebrates living on the seafloor and buried in the mud. This fauna includes brittle stars, clams, snails, and polychaete worms (see photo).

Jerry McCormick-Ray has been inspecting some of these samples, in preparation for her sampling in the shallow waters of the inner shelf. Her goal is to understand how the productivity of the Bering Sea affects the distribution of these benthic organisms, some of which are prey for diving air-breathing predators like walruses and eiders.

Today we encountered several new species. We saw the first whales (one minke and two humpbacks) and the first pinnipeds (spotted seals and fur seals). We also saw our first bird sitting on the ice: a Glaucous gull chilling out and watching the ship go by.

The scariest looking organism - so far - is the chaetognath, also known as the arrow worm (see photo). Even though they are invertebrates, chaeteognaths are not worms at all. They have a distinct head, trunk and tail. They are rather peculiar, with all species being hermaphroditic and carrying both eggs and sperm. Thus, they belong to a phylum of their own (chaetognatha).

Chaetognaths are a major component of the plankton world-wide. Most live in the water column and are transparent or translucent and torpedo shaped. However, about 20% of the known species are benthic and can attach to algae or rocks. They have fins and a pair of hooked, grasping spines on each side of their heads that they use for hunting.

These voracious predators cruise the water column searching for copepods. Fortunately for us, they are only a few millimeters in size. Hey, its friday 13th after all!!!

** USCGC Healy: Thursday, April 12, 2007 (see images for this day)

We encountered the first ice pieces during the early morning hours, some sparse brash ice (see photo). So far larger spans of sea ice have eluded us, though ice fingers sit off in the horizon observing us as we complete our stations. We will surely meet again later.

Seeing the first bits of ice on this Bering Sea journey.

First bits of ice, and ice on the horizon. photo by D. Hyrenbach.

We completed three stations in Bristol Bay to obtain early-season samples in this area, then the Healy started making its way up the middle shelf of the eastern Bering Sea along the 70-meter isobath. The plan is to sample a series of closely spaced (10 nautical miles or 18 kilometers) hydrographic and plankton stations all the way up to St. Lawrence Island. This means conducting a CTD operation at each station getting water samples, and getting temperature, conductivity, salinity, oxygen, PAR and other data types in the water column at each station. As we make our way north along this route for the next few days, we will visit four NOAA oceanographic moorings (M2, M4, M5, M8). Moorings are usually in place year-round and provide a continuous record of physical and biological properties at a number of depths in the water column. These greatly complement the intensive single-point sampling collected from an oceanographic cruise. The NOAA vessel Miller Freeman, will replace the winter-time sub-surface moorings with summer-time surface moorings. The Miller Freeman will be working in the Bering Sea after April 18.

Though we have not sailed into the ice yet, everybody is getting ready. The seal team launched all three inflatable boats this morning, as part of a dress rehearsal for the seal tagging trips ahead. The bird and walrus observers set up a computer system to document sea ice conditions using visual observations from the bridge and a catalog of time-stamped photographs. Is it brash ice, pancake ice, small floe, older, newer, snow-covered? Everybody onboard has a trigger finger on their cameras, ready to start snapping ice photos.

** USCGC Healy: Wednesday, April 11, 2007 (see images for this day)

The second day of the cruise began with the promise of continuing sunshine and flat seas. With four stations completed yesterday in the vicinity of Unimak Pass, the Healy headed northeast at night toward the shallow waters of Bristol Bay along the CN (Cape Newenham) line.

SAFETY: The activities of the day were punctuated by an abandon ship drill. The alarm sounds and all scientists and crew of the Healy converge in the aft (back) helicopter deck of the ship, seeking their assigned raft. Officers hold numbered cards up to indicate the gathering

Demonstration of a survival, immersion suit, or a "gumby" suit by Healy personnel. photo by D. Hyrenbach.

point for each raft group. The first task is to account for the whereabouts of everyone onboard the vessel to ensure nobody is left behind if we need to abandon the ship. If it was a true emergency, the second task would be to collect emergency supplies and rescue equipment, and put on the immersion (or gumby) suits. As part of the emergency drill, personnel from the Healy walked us through the entire process of donning gumby suits: a good fit of the survival suit is critical for comfort and safety. They demonstrated the emergency equipment incorporated in the suit: a whistle, a mirror and a strobe light provide different ways to attract the attention of rescuers. The best part: you can attach the strobe light onto your head using a velcro strap. They have thought of everything!!!

After the drill is complete, science goes on. More CTD and multi-corer casts on the shallow shelf (depth < 200 m) yield physical data on the water column properties, and samples of water and mud for chemical and biological analysis. Some of these mud samples also provide researchers an opportunity to inspect the creatures (molluscs, worms, crustaceans) that live in the mud (known as infauna). Researchers also use bongo nets equipped with different mesh sizes to sample different size classes of zooplankton in the water column. So far, the water column has been very well mixed from top to bottom, and the nets have collected some euphausiids. The acoustics have revealed scattered euphausiids and some fish (pollock) in the water. The seabird team also started surveying today along the offshore - onshore transect. Most birds sighted today were gulls (glaucous-winged gulls and black-legged kittiwakes), with the occasional alcid (common and thick-billed murres) and petrels (northern fulmars). The most exciting sighting of the day was a small balaenopterid whale with a falcate (cycle-shaped) fin; most likely a minke whale. Last year we saw several of these whales close to the ice, so we look forward to getting better looks of these animals as we make our way farther north.

Coming into fog. photo by D. Hyrenbach.

This evening we had the first hint that the ice may be close. After a day of warm (1-2°C) water, we entered a thick fog bank overlaying very cold water. The CTD measured cool surface waters (-0.5°C) and revealed a lens of cooler and fresher water overlaying saltier and warmer water. Is this a signal of the retreating melting ice? We will soon find out.

As the number of completed stations increases and the people and the machines get into the groove, a rhythm is starting to develop. The pace and scope of the research will change once we get to the ice. We are ready.

** Begin cruise - USCGC Healy: Tuesday, April 10, 2007 (see images for this day)

The first day of the cruise has been sunny and calm with 1-2°C air temperatures. We are becoming familiar with the ship, captain and crew. In the afternoon, we had a meeting with the captain, the executive officer and key personnel involved with our researchers. During this meeting, we went over the workings of the ship and the every-day logistics of life at sea. Even though the Healy is a large ship and crew, it feels like a big family, and we have been made to feel very welcome onboard.

A science meeting this evening presented us with an overview of the research goals and specific needs of each science group. Forty-three scientists from ten different research projects are onboard. With so many scientists working together, logistics are critical to the work and sampling.

A CTD (conductivity, temperature, depth) rosette on deck.

A CTD unit on deck. Water samples at various depths are collected in the grey cylindrical "niskin bottles". photo by D. Hyrenbach.

At these meetings, researchers go over minute details, such as the way sampling stations will be numbered, the sequence of samples to be taken at each station, and how much water each sample requires so that we collect enough for everyone. The order of the samples taken from the CTD (conductivity, temperature, depth unit) is critical to ensure that certain delicate measurements are accurate. For example, the concentrations of gases dissolved in water have to be the first sample after the CTD is back on deck, though chlorophyll samples can occur later.

Other measurements require special instruments to avoid contamination from surroundings. Researchers are using a "clean" water instrument to sample iron in the water column (see "vane" sampling device photo) so that the ship (made of metals) does not contaminate the samples. Iron in the water column must be sampled before we take mud samples (with a multi-corer, see photo) because stirring up sediments could contaminate iron measurements. A cruise is like a delicately choreographed ballet.


Vane, iron-sampling device. photo by D. Hyrenbach.	Multi-corer for sea-floor mud samples. photo by D. Hyrenbach

We departed Dutch Harbor at noon and headed north towards the first station off Bering Canyon. This is a very interesting place on the shelf where water from the basin (the deep-water part of the Bering Sea) moves toward shore. Sampling here will give researchers a sense of the properties of the water that mix onto the shelf from offshore. We are taking three measurements at this deep-water site (water depth is 1186 meters): a CTD (conductivity-temperature-depth), an iron sample, and a multi-core sample of mud. After this station, we will move south towards Unimak Pass, one of the Aleutian Island gateways between the Bering Sea and the North Pacific. Here we will complete a shallow-water station (water depth will be less than 100 meters). Tomorrow we start making our way north towards the ice, along the 70-meter isobath.

** Pre-cruise - USCGC Healy: April 9, 2007

Dutch Harbor, Alaska in the Aleutian Islands chain is on Amaknak Island, adjacent to Unalaska (description on alaska.com). USCGC Healy is in port at Dutch Harbor. Scientists and expedition participants have been arriving from many locations yesterday and today for the journey. Supplies and equipment that have been barged or flown in have been located and are being loaded onto the ship. This is a time for setting up work spaces and lab equipment, plugging into the ship's computer network and setting up accounts. tying down anything that could slide or fall when underway as the ship moves, getting orienting to the ship's layout, and finding assigned sleeping quarters and the mess hall for meals. This is a very active time before scientists and crew settle into their intended work. Tomorrow we will leave port, heading north to begin our expedition.

** Pre-cruise - USCGC Healy: March, 2007 (see pre-cruise images)

Planning a research cruise begins long before the ship sails. Because this expedition involves many scientists from different institutions, plans had to be laid out a long while in advance. We have reached a point where the ships are scheduled and travel arrangements have been made. A second ship, NOAA's Miller Freeman will be in close proximity for part of the Healy Ice Expedition. We are ordering the last of the equipment we will need, and will be able to load the Healy here in Seattle on March 21 and 22 prior to her departure to Dutch Harbor, Alaska. The scientific team will fly to Dutch Harbor in the Aleutian Islands where the research cruise will begin. When the cruise leaves the dock in a month, we will post daily log entries so you can read along and participate in the excitement of new discoveries, as well as the excitement (and boredom) of life and work at sea.