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Week 06
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Dispatch 22

Faure Islands weather station installation crew. At rear, from left to right: Bob Beardsley, Woods Hole Oceanographic Institution (WHOI); Jesse Doren, Jeff Otten, Raytheon Polar Services Corporation (RPSC); Mark Christmas, At front, from left to right: Andy Girard, WHOI; David Green, RPSC.

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Photograph by Mark Christmas

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Installation of a weather station

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May 28, 2001

Latitude: 67° 53’ 408” S
Longitude: 68° 13’ 914” W

Temperature: -0.7° C (31° F)

Wind Chill: -19.3° C (-3° F)

Seas: Calm


Humpback whales logging

Fur seals jughandling

Penguins in Lazarev Bay

The past four days have been very productive. We left Lazarev Bay and headed north along Alexander Island to return to an area we called the graveyard. It had been full of icebergs that rose like tombstones with the surrounding sea covered in grease ice. Seals and birds were everywhere. It had changed completely. The icebergs had moved on. On the way to the graveyard, the bridge had spotted a whale early in the morning and Catherine Berchok had heard a lot of humpback sounds in the area in which the whale was spotted. The decision was made to return to this area alongside Alexander Island.

The weather was perfect for the Zodiacs. A flat, calm sea, overcast skies, and areas of brash ice. By day’s end, six minke and seven humpbacks had been sighted with successful biopsies obtained from one minke and three humpbacks. Exhilarating is the word that comes to mind to describe the feeling of approaching these animals. Ari Friedlaender at the bow with his crossbow at the ready. Catherine Berchok in position to photograph the whales. The pilot following Ari’s hand and voice directions. Members of the science party keeping their eyes on the lookout for whales. For the last biopsy, we approached a humpback cow and calf who were logging. Logging is a resting behavior. Startled from their rest, the whales dove quickly.

While looking for whales, we came upon fur seals engaged in a behavior known as jughandling. It was the strangest sight. From a distance, they looked to me like flotsam. When we got closer they looked like otters feeding. When we came alongside, you could then see that they were fur seals with one pectoral flipper held between their flippers.

Two automatic weather stations were installed. The first on one of the Kirkwood Islands and the other on one of the Faure Islands. These weather stations, designed and built at the University of Wisconsin, Madison, automatically send data to passing satellites. The data is then transmitted to the university, where they are able to monitor temperature, wind speed and direction, barometric pressure, and relative humidity. They will provide weather data for years to come.

The bird observers diet-sampled two Antarctic petrels. The best was yet to come. As the weather station was installed on one of the Faure Islands, the bird team went to another. They returned later in the evening having diet-sampled six Adélie penguins.

Through all of this, the MOCNESS and BIOMAPER II have been conducting in-depth studies of the life in the sea. I’ll give you an update of their work in the next dispatch.

We’ve been invited by the commander of the Argentine research station San Martin to visit. The station is on the Western Antarctic Peninsula and is home to 19 researchers. We’ll join them for coffee. I’ll let you know how the visit went.

Some more questions from our viewers:

Q: During your long trip, have you found it is difficult to stay focused on daily routines with the extreme temperatures there and, if so, how do you overcome these problems?

A: I haven’t found the cold to be a problem. The marine environment around the Western Antarctic Peninsula could be called mild compared to the severe cold found on the continent. One of our coldest days was -7.0° C (19° F) with a wind chill of -30° C (-22° F). The ship is climate controlled.

Q: Since Antarctica is uninhabited by humans, who owns it and does this cause any hindrance to research?

A: No nation owns Antarctica. It is protected and governed by the Antarctic Treaty, which was initiated in 1961 with 12 nations signing on. It now includes 43 nations. The area south of 60° S latitude has been set aside as an area of “peaceful research.” This is a great aid to research.

—Mark Christmas, field producer

Have a question for Mark or the SeaLab team about the expedition or life at sea in Antarctica? In every dispatch, Mark will answer selected questions from readers.

[Note: does not research or copyedit dispatches.]

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Dispatch 23

A bust of the namesake of the San Martin Station, honoring its 50th anniversary.

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Photograph by Mark Christmas

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San Martin Station

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May 30, 2001

Latitude: 67° 56’ 333” S
Longitude: 68° 49’ 011” W

Temperature: -0.7° C (31° F)

Wind Chill: -19.3° C (-3° F)

Seas: Calm

It snowed all day yesterday. This did not deter us from visiting Commander Carlos Martin and the 18 under his command at the Argentine Research Station at San Martin. The station is celebrating its 50th anniversary this year.

The Nathaniel B. Palmer dropped anchor about a mile and a half offshore and the Zodiacs were busy all morning ferrying the landing party of crew and scientists to shore. Our visit tripled the number of people at the station.

As we approached the station, the Argentine and United States flags were whipping in the wind on a promontory that also has a statue of namesake San Martin and a memorial wall with plaques bearing the names of those who have served at the station. Commander Martin gave an informative presentation on the history and culture of Argentina followed by a tour of the station. The team at San Martin has been there for two months of a one-year deployment. Our hosts were gracious and endearing. We were warmly welcomed and treated to a meal prepared in our honor. Hugs and handshakes marked our reluctant departure as the last light faded from the gray and snowy sky. From all of us to Commander Martin and crew, fue un placer.

The visit was special to all of us but perhaps more so to two of our number. Palmer crew member Robert “Bobby” Ayler has now set foot on seven continents, and Baris Salihoglu of Old Dominion University has become the first Turkish oceanographer to land on the Antarctic continent. Congratulations Bobby and Baris!

The MOCNESS, VPR and BIOMAPER II teams have been busy. In the week since we’ve left Lazarev Bay, they have identified high volume krill patches with BIOMAPER II and VPR and then done a MOCNESS tow through the same patch. The buckets were full of krill. Not surprisingly, humpback whales were sighted and heard by sonabuoys in the vicinity of the high-density krill patches. As the studies were conducted under the surface, I went on deck and saw numerous seals and birds in the surrounding waters.

How the time does fly. It’s hard to believe that we’ve been at sea for 37 days. In one week, we’ll be back at the port in Punta Arenas, Chile. We’ve two more days of science left, then five days to cruise to port.

Some more questions sent to us via e-mail:

Q: How does it feel to be in Antarctica, so physically separated from civilization? Do you encounter abundant life all around you? What is the most abundant wildlife you see? Is the night sky there very clear? —David in La Jolla, California

A: It does at times feel other-worldly here in the Southern Ocean. More often, the power of the natural forces that shape this environment inspire awe.

It is both spectacularly beautiful and desolate in the same breath. The oceans are teeming with life. We have found areas of great abundance and others less so. The physical processes that create the conditions for life in the seas are being studied in-depth. Where the sea is rich in life, the surface tends to be rich as well.

We have spent the majority of this cruise in the open sea with rough weather, including a number of gales. We’ve had a few nights where the skies were very clear. Tonight is one of those nights, probably the clearest night we’ve had thus far. A pleasure to behold.

Q: Have you noted any dramatic changes in climate?

A: Eileen Hofmann answers this one:

Climate change occurs slowly, and as a result it takes several years of monitoring in an area to see changes. Because our cruise is only about 1.5 months long, it is not long enough to see major changes in climate.

However, what we can see from our cruise, is that the winter freeze-up of the ocean is only now starting. The cooling of the ocean that needs to happen before sea ice forms has not yet progressed to the point to allow this to happen. In previous years, our study area already had sea ice by early June. Whether what we are now observing is a dramatic change or simply part of a natural cycle can only be determined by continued observations.

Thank you for your question and for your interest in our cruise.

Thanks to Eileen Hofmann for answering this one!

Q: Does the ship stop anywhere during the journey or is it always moving? —Arun Kumar

A: One of the constants on board the Palmer is the sound of the engines. In the labs, which are in the lower decks, the floor and counters vibrate with the engine sounds. As you go to upper decks, the sound is increasingly muffled, but everpresent. While the engines are always running, the ship is not always underway. When the CTD probe is put into the water or Zodiacs are deployed, the ship holds station. I asked Captain Watson to describe the process.

Captain Watson’s response:

A large part of our basic oceanography work involves getting water samples from specific geographic locations, called stations. The first step is to provide the mate on watch with the co-ordinates of the station in order to give us an aiming point. With this entered into the ECDIS (electronic chart display) we’ll approach the station directly into the wind for maximum controllability of the ship at slow speed.

I’ll normally approach at full ahead and start reducing speed at around a half mile off. Ideally, I’ll continue slowing until I’m stopped directly on location. The Palmer has controllable pitch propellers that allow us to put whatever amount of power we need into the water and control it very precisely by varying the amount of pitch or “bite” that the blades are applying to the water. This also enables us to go from full ahead to full astern without stopping or changing the engine speeds by reversing the pitch on the blades. This allows us to fine-tune our position.

In addition to the main engines, we’ve also got bow and stern thrusters that allow full positioning of the ship in any direction and allow us to maintain control if we’re running at such a slow speed that the rudders are ineffective, i.e. launching or deploying the BIOMAPER II or towing a MOCNESS net at 2 knots in a crosswind. Once we’re in position over the location it’s a matter of using the engines and rudders to keep the ship pointed into the wind and balancing engine power against the wind and seas.

As a matter of pride, I prefer to use main engines only because it puts less noise in the water and takes a little more skill than using the thrusters, but I won’t let that get in the way if a problem comes up and I need the thrusters.

In the Palmer’s case, we have the ability to hold station in much greater sea and weather conditions than would allow deploying instruments, so there’s a built-in safety factor there when it comes to deciding whether to risk personnel and equipment in marginal deployment conditions.

I should mention that we’ve also got a computer control system on board that allows us to tie in the engines and thrusters to our positioning data and allows us to hold station completely hands-off down to a precision of approximately one meter. Because equipment and electronics can fail, our policy has always been that any mate who intends to stay on board must be able to handle the ship in any emergency situation. So far, almost everyone that’s passed through has made it.

Best Regards,
Captain Michael Watson

Thanks to Captain Watson for answering this one!

Remember, if you have a question, drop us a line!

—Mark Christmas, field producer

Have a question for Mark or the SeaLab team about the expedition or life at sea in Antarctica? In every dispatch, Mark will answer selected questions from readers.

[Note: does not research or copyedit dispatches.]

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Dispatch 24

May 31, 2001

Latitude: 67° 22’ 382” S
Longitude: 69° 36’ 328” W

Temperature: -4.7° C (24° F)

Wind Chill: -16.1° C (3° F)

Seas: 4 to 6 feet

We are nearing the final hours of the research portion of the cruise. BIOMAPER II has been in the water and is just now being pulled. We are approaching what will be the 99th CTD station. As we head back to port, I’ll try to summarize some of what we’ve learned this past month. Spirits are high.

Six days till we reach port. Still ahead, the Drake Passage!

Here is a question sent in to us via e-mail:

Q: I’m a 16-year-old kid living in Texas at the moment. A while ago I read a book about Antarctica and since then it’s become my dream to go there one day. Someday I will. How did you get to where you are today? Have you always wanted to go to Antarctica? How did you get such an amazing job?

I’ve read about the early explorers and am fascinated by their adventures. I especially loved learning about Captain Cook and Ernest Shackleton. I am still unsure of what I want to major in, but I was thinking about botany or marine biology. What are some fields that the marine biologists and oceanographers on the expedition have specialized in?

I wish you the best on your expedition. —Adrianne in Texas

A: Dear Adrianne,

Your question was forwarded to me. My name is Cabell Davis, and I am a scientist at Woods Hole Oceanographic Institution. I am a biologist who specializes in zooplankton, like krill and copepods.

Your passion for Antarctica is commendable and certainly justified. This expedition is my first one down here in the Southern Ocean, and I must say this place is awe-inspiring. Like you, I had read books and seen films on Antarctica, but being here and seeing it firsthand is amazing.

I really hadn’t given much thought to working down here until I was asked to help plan for the Southern Ocean GLOBEC Program several years ago. I had helped establish the GLOBEC Program on Georges Bank (off Cape Cod, Massachusetts) and was asked to join the planning team for the Southern Ocean. At that point I began reading about the history and natural history of this area and became excited about the prospect of joining an expedition here.

You asked how one gets such an amazing job. Well, I always have had a keen interest in nature even as a child, and in college I majored in biology with the thought of going into medicine, but after working in a hospital during my junior year, I opted for marine biology instead. I attended graduate school at the Boston University Marine Program in Woods Hole where I studied the zooplankton of Georges Bank. That work evolved into further studies on Georges Bank and helped formulate the GLOBEC study there.

The main goal of my research is to understand what controls the size of zooplankton populations in the sea. I have developed laboratory culture methods to grow the animals under controlled conditions, and together with Scott Gallager at WHOI have developed an underwater video microscope we call the Video Plankton Recorder or VPR.

I use the data from these lab and field studies in computer models of ocean circulation and population growth to better understand how the plankton grow, die, and are moved around by water currents. We work with physical oceanographers who understand and model ocean circulation patterns. This expedition is a real team effort. We have several principal investigators like me on board, each of whom has their own project, each project fitting into a large overall effort to study krill plus their prey and predators.

On this cruise, I am primarily focused on collecting data using the VPR, which takes 60 pictures per second as it is towed through the water on top of the BIOMAPER sled. These pictures are analyzed in real time by the computer, and subimages of plankton are saved to disk, sorted, and counted by our computer.

Just a couple of hours ago the VPR passed through a very dense patch of large krill, which generated many pictures of these animals. We are currently training the computer to identify different types of plankton on its own. We then will plot the patterns of the different plankton together with the environmental data on water temperature, salinity, etc. to see where the krill and their prey live in relation to environmental conditions.

My specialty is really copepods, which are a prey item for krill. Copepods are the most numerous animals on Earth (with the possible exception of round worms). They are very plentiful in both marine and freshwater environments. These small crustaceans are a primary food source for the larvae of fish, crabs, and many other marine organisms, including krill, so they are part of the base of the food chain in lakes, rivers, and the ocean.

Because many animals want to eat them, copepods have to be very fast to avoid being consumed. In fact, they are the fastest animals on Earth for their size. We have measured them swimming at 1 knot and since they are typically 1 millimeter long, that means they can swim 500 times their own body length per second. We usually think of a cheetah as the fastest animal but for a cheetah to go 500 body lengths per second, it would have to run 2,000 miles per hour! And the copepod is doing this through water, not air, so they are very specialized little swimmers. They flip their appendages (like a lobster tail flip), and their body forms into a bullet shape that is propelled through the water very fast.

There are many other scientists on board doing many fascinating things, including studying seabirds (including penguins), mammals (including whales and seals), the physics of seawater motion and its interaction with the atmosphere, and the phytoplankton or microscopic plants that form the base of the food web in the ocean.

It is hard to describe all this work in one page, but I hope the sketch I have provided you sheds light on your main questions. It is really a fun job and a lot of work at the same time. I encourage you to pursue your interests in Antarctica and marine sciences. With effort and persistence someday you will be down here as well.

Thanks to Cabell Davis for answering this one!

Remember, if you have a question, drop us a line!

—Mark Christmas, field producer

Have a question for Mark or the SeaLab team about the expedition or life at sea in Antarctica? In every dispatch, Mark will answer selected questions from readers.

[Note: does not research or copyedit dispatches.]

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Dispatch 25

A riot of color: sunset off of Adelaide Island.

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Photograph by Mark Christmas

June 1, 2001

Latitude: 67° 22’ 382” S
Longitude: 66° 22’ 723” W

Temperature: -4.7° C (24° F)

Wind Chill: -8.4° C (17° F)

Seas: 2 to 4 feet

Last night was beautiful. The moon rose at 1500 hours. Its reflection created a path of light on the calm waters that led to the aft working deck. Adelaide Island was just visible in the distance, a blue shadow. We moved closer to shore to find some ice for a last deployment of the ROV SeaRover. The moon was at the same elevation but on the mixed pancake and brash ice its beam looked like that of a celestial lantern lighting our way.

Yesterday we had a crossing ceremony. The ceremony is a rite of passage for those crossing the Antarctic Circle for the first time. It was the ultimate team building exercise. I’m sorry that I can’t tell you more about it, but I don’t want to incur the wrath of King Neptune.

A more glorious day for any event you could not have dreamed. A partial rainbow greeted us at sunrise, and it made me think back to the rainbow that appeared as we left port on April 24. The realization that the day was the last we’d spend this close to Adelaide Island was on my mind. And with it was the thought that this journey of research and exploration would soon be ending. So the lavender clouds of morning and the snowcapped mountains painted pink by the sun seemed even more beautiful.

Back to sea for one final tow of the BIOMAPER II followed by some deep-water CTDs, and we’re on our way.

In five days, we’ll be back in port. We’re now entering the southern area of the Drake Passage. Seas are building, and the winds are gusting to 35 knots. How rough will it be? Check back to find out.

Here are some questions from our readers.

Q: I have a problem with my camera batteries always going dead. I imagine that with the cold temperatures your batteries would die in minutes. You can’t use a solar charger since there is no sun. Did you bring a case of batteries? Or do you have a trick to keep the batteries from running low? —Kevin Daney in Virginia

A: The answer to that is yes and yes. I brought plenty of lithium batteries for my camera gear. I also brought rechargeable nickel-metal hydride batteries. I use the rechargeable batteries as much as possible. When I will be outside for extended periods of time or if I leave the ship on a Zodiac, I use a customized power supply (courtesy of Phil Leonardi and the National Geographic Society Photo Engineering shop).

It’s a modified AC power adapter from Nikon (note: the modification voids the warranty!). Two four-pack AA-size battery packs wired in parallel provide the power. The cord is about six feet long. I place the battery pack in my vest under at least two layers of clothing. I keep the cord draped around my neck so it’s always ready. I carry extra AAs so I can replace the camera batteries at the earliest opportunity, but I always have the custom-made backup.

Q: Historic expeditions to Antarctica have frequently included an artist. Does any member of your team paint? Do you have an artist working with you? —Carmel Digman, Whitestable, England

A: Peter Wiebe answers this one:

Sue Beardsley is an artist. One does not have to paint to be an artist, and I am sure that what she has experienced on this cruise will carry forward in her work. One of the great biological oceanographers, Sir Allister Hardy, was himself a very accomplished artist and did a lot of the documentation of the Discovery cruises in the Antarctic in the 1920s via watercolor painting. The reason an artist or photographer was brought along was to document pictorially what was being experienced. You [Mark Christmas], of course, qualify for that position, and given the technology on board, we who hold still- or video-cameras qualify as well.

Cheers, Peter

Q: Do the crew or the scientists have opinions as to the potential impacts of tourism operations in the Antarctic region? Is the environment and wildlife under threat at all? Should tourism be encouraged in the Antarctic region? —Alex in Canberra

A: I asked Peter Wiebe and Ari Friedlaender for their opinions. Thanks to them both!

Chief Scientist Peter Wiebe, Woods Hole Oceanographic Institution:

Tourism in the Antarctic? This is one that I am ignorant about. I know that tourism in this part of the world exists. But just how many people actually get down here now is not something I have a feeling for.

By and large, to get here takes large vessels and generally big operators—like the cruise boats in the Caribbean. I suspect they have their favorite haunts and most of the Antarctic coastline is unvisited, and that is not likely to change very soon.

The favorite haunts, however, may be important places ecologically and tourist pressure holds the potential for some kind of disruption to the natural structure and rhythm of the system. And with large vessels comes the possibility of large accidents, wrecks, spills, etc. The cold, harsh, Antarctic ecosystem is also thought to be fragile, and if true, this fragility needs taken into consideration.

On the other hand, I suspect that the more people know about the place, the better the chance that the system will remain a refuge from man’s onslaught of the world’s ecosystems in general—or is this just wishful thinking?

Ari Friedlaender, International Whaling Commission:

Great question, and quite relevant to our work down here as well. One of the many things that makes Antarctica unique is the historically varying amount of human presence and influence on the ecosystem. This is the impetus for researchers from many different disciplines (biology, ecology, physics, chemistry, geology, oceanography, etc.) to conduct experiments and collect data that cannot be obtained anywhere else in the world. Among the most important of these are those measuring anthropogenic effects in various systems.

Is the environment and wildlife under threat at all? Yes. Commercial whaling and sealing operations, which ran from the 19th century until the recent past, removed millions and millions of animals. Some species became locally extinct, while others were depleted to levels from which they are only now beginning to recover, if that is possible. So, the removal of apex predators from the marine ecosystem certainly has impacted the present day dynamics that we are trying to measure.

The questions that I am trying to address involve understanding what factors (physical, bathymetric, biological) affect the distribution of certain whale species in Antarctica. This knowledge will lead to a better understanding of the habitat requirements of these animals. We can then begin to generate models that will predict how environmental changes, human-induced or otherwise, might change whale distribution and thus the dynamics of the marine ecosystem in Antarctica.

While tourist operations are not likely to cause direct mortality to animals, there is the potential that the physiological stress caused by visitors (chasing whales, invading seal breeding areas, sea bird nesting sites, and penguin rookeries) could negatively impact the reproductive success of animals in the future.

There are strict guidelines in the Antarctic Treaty designating specially protected areas to be left undisturbed. I strongly believe that Antarctica must be experienced to be fully appreciated. It is difficult to grasp the full scale and magnitude of the Antarctic without actually being here. Documentary videos and multimedia can certainly present an amazing amount of the world down here, but nothing can match the firsthand encounters. In that respect, I think that it is important for people to have that experience, as it facilitates empathy and a desire to conserve this unique part of the world. At the same time though, I would be very cautious about the amount of tourism and traffic that is allowed to occur, especially in the biologically sensitive areas mentioned above.

All of the legislation and regulation of Antarctic tourism should take a precautionary approach to ensure minimal environmental impact. In fact, research is under way at certain penguin and seal breeding sites to study the effects of tourism/visitors on reproduction and survivorship.

Remember, if you have a question, drop us a line!

—Mark Christmas, field producer

Have a question for Mark or the SeaLab team about the expedition or life at sea in Antarctica? In every dispatch, Mark will answer selected questions from readers.

[Note: does not research or copyedit dispatches.]

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Dispatch 26

The final recovery of BIOMAPER II complete, Andy Girard, upper left, and Joe Warren prepare to shut down winch operations.

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Photograph by Mark Christmas

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A cabin on the Palmer
Palmer’s mess hall

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June 4, 2001

Latitude: 55° 29’ 401” S
Longitude: 65° 09’ 732” W

Temperature: -3.1° C (26° F)

Wind Chill: -4.8° C (23° F)

The past three days have seen a flurry of activity onboard the Nathaniel B. Palmer. The final scientific studies were completed as we reached the 200-mile territorial limit of Argentina. XBT probes and sonabuoys were deployed up to that point. Labs are being packed, and samples are being prepared for shipment. Cruise reports are being written. Customs forms are being filled out (we must clear Customs since we are re-entering Chile), and cold weather issue gear is being packed.

I’ve seen more of the crew awake at the same time these few days than at any time in the past month. The sun was up by 0800 hours, the topic of conversation at breakfast! It’s a clear sunny day as we pass through the Straits of le Maire on our way to the Strait of Magellan. Erik Chapman and Ari Friedlaender are on the bridge with binoculars, looking for birds and dolphins. Ari sighted a pod of southern right whale dolphins. A treat. Smiles abound.

The sunset and moonrise tonight were brilliant. If ever there was a reward for enduring the short days of the Antarctic, this was it.

It’s very likely that we’ll arrive in port tomorrow evening, one day early. I don’t believe you’ll hear many complaints from the crew.

Thanks for keeping up with the cruise. The personal sacrifice of the scientists and the crew onboard the Nathaniel B. Palmer and Laurence M. Gould on this, the first of the Southern Ocean GLOBEC cruises, is contributing greatly to the body of knowledge of the Antarctic ecosystem. The second cruise will begin in July. Many of the scientists on these ships now will take to the sea again. To them, thanks for doing what you do, and for doing it so well. And to their families and loved ones, thanks for accepting the separation that this research requires so that we all may benefit.

Although I’ll probably have time to file only one final dispatch from port, we’ll keep answering questions through the end of June. I plan to file a dispatch from National Geographic headquarters in Washington, D.C., to give this journey some closure.

Eighteen hours till we reach port!

More questions from our readers:

Q: How have your expectations of Antarctica measured up? What surprised you? What disappointed you?

A: The marine experience was much different than the picture of Antarctica I had in my mind. The stormy weather of the first portion of the cruise and the 24-hour science were grueling. The time we spent in the ice of Lazarev Bay was more in keeping with the mental image I carried down with me. There were no real surprises or disappointments.

Q: Compared to the coldest day in Maryland you can remember, describe a normal day in Antarctica. —Jim, Ben, Alex, and Barbara Wolf

A: The marine climate in Antarctica is very different from the climate on the continent. The seas keep the temperatures mild. The coldest I remember is a day when the wind chill was -30° C (-20° F). The more common temperatures for us have been between -1° C and -9° C

Q: Did you see any unusual creatures?

A: The most unusual creatures I saw were microscopic. Amphepods, copepods, pteropods, and the other zooplankton that were brought up in the MOCNESS nets were by far the most unusual.

Q: How are your ribs? Do you miss home?

A: My rib has healed very nicely. There is still some pain but it pales in comparison to the early weeks of the cruise. I do indeed miss home, and as we get nearer to the port at Punta Arenas, Chile, home seems closer than ever!

Q: Could you tell me what kind of distances krill migrate in a lifespan? —Vincent Couwenberg

A: Eileen Hofmann answers this one.

Antarctic krill are unusual among marine zooplankton in that they live for four to five years. During the first year or so of their life they are not good swimmers and are moved around by the ocean currents. After they are one year old or about 15-20 mm in size, Antarctic krill are good swimmers and have the ability to move differently from the ocean currents. A result of this is that Antarctic krill can potentially be moved long distances from where they were spawned, either by the ocean currents or by their ability to swim.

One interesting idea that is now receiving much study is that the Antarctic krill that are spawned along the west coast of the Antarctic Peninsula form the seed population for the krill that are found around South Georgia, which is an island in the Scotia Sea. It is believed that the ocean currents carry Antarctic krill the 1000 km from the Peninsula to South Georgia.

The speed of the Antarctic Circumpolar Current, which goes all the way around the continent, is such that it is possible for Antarctic krill to make a complete circuit around within its lifetime. Whether or not this happens is not known. However, studies of krill population genetics are now ongoing to try and resolve this issue. If these studies show that krill from all around the Antarctic are genetically similar, then this is evidence for continual mixing of the populations. If the krill genetics are different, then the transport/migration of krill is more limited.

Within a given region, the adult Antarctic krill are known to migrate offshore to the edge of the continental shelf where they spawn in the summer. In the fall these krill then migrate to the inner portion of the continental shelf. This migration, which can be 200 km, is thought to be in response to the better availability of food in the inner shelf region in the fall and winter. On our cruise we have seen this pattern. The offshore waters have few large krill. The inner shelf waters contain the major abundance of large krill.

I hope this answers your question. Thanks for your interest in our cruise.

Thanks to Eileen Hofmann for answering this one!

Remember, if you have a question, drop us a line!

—Mark Christmas, field producer

Have a question for Mark or the SeaLab team about the expedition or life at sea in Antarctica? In every dispatch, Mark will answer selected questions from readers.

[Note: does not research or copyedit dispatches.]

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