Music by Synthhead. Courtesy of Beatpick.com.

At Site U1359, Hole U1359B,
Position: 64º 54.25’S, 143º 57.63’E
Water Depth: 3100 meters

ABOARD THE JOIDES RESOLUTION, OFF THE COAST OF WILKES LAND, ANTARCTICA– Hi everyone! As we approach our 2000th meter of drilling I thought I would change things up a bit with this blog and send along some photos of the birds we’ve been seeing. The Southern Ocean is the coldest and windiest on Earth, but it also one of the most bountiful. During the 3 or 4 months of long days and short nights, the “farm” operates 24/7. The plants that live in the sunlit waters here are nourished by nutrients that mix upwards from the deep sea and go into overdrive building their cells. It’s easier for nutrients to mix upwards into the sunlit upper waters here simply because the water column is “isothermal”. This means that we see very little variation in the temperature of the sea between the surface and the bottom waters over 3000 meters below us. It is all close to 0 degrees Celsius. This means that it takes very little energy to move dense cold water from the deep upwards because the surface water is also cold and is almost as dense. So the plants have everything they need. The wind and circulation drive the mixing, which brings in the nutrients, and the sun keeps the farm growing nearly 24 hours every day. Plants (mostly single-celled protists called diatoms) grow fast and the small plankton that eat the diatoms grow fast as well. Which brings us to the birds…..

Albatrosses in a storm.

Our ship is constantly surrounded by Albatrosses, Petrels, and Skuas. Sometimes we see more than 100 birds surrounding the ship. They swoop and dive, looking for food in the water, either plankton or small fish, or perhaps they think we are land. We haven’t seen one try to rest on the ship yet. In fact the Albatrosses rarely set down at any time. They fly 1000’s of miles from their breeding colonies and are at sea for months and even years at a time.

Here are some photos of the seabirds we’ve seen so far.

These first two are of Black-browed Albatrosses (Thalassarche melanophrys). They live throughout the Southern Ocean and breed in places like the Falkland Islands and South Georgia. They can live to be as old as 70 years and spend long periods of time at sea, even encircling the globe. They feed on krill and small fish – that in turn eat diatoms and smaller plankton.

Black Browed Albatross

Black Browed Albatross

The most common bird we saw at our drill sites close to the Antarctic continent were the Pintados, also known as Cape Petrels (Daption capense capense). The name Pintado comes from the Spanish word for “painted”. They live throughout the Southern Ocean, mainly eating krill, especially on and near the continental shelf of Antarctica in summer. A 2009 census estimates there are over 2 million Cape Petrels alive today.

Cape Petrel (Pintado)

Cape Petrel (Pintado)

Cape Petrel (Pintado)

We’ve also been surrounded the past few days by Southern Giant Petrels (Macronectes giganteus). These are indeed big birds….females can weigh up to 18 pounds. Sometimes they are called “stinkers” as they can spit a foul-smelling liquid at predators or when they are perturbed.

Southern Giant Petrel

Southern Giant Petrel

I hope you enjoy these photos! I’ll get back to our science and progress next time and I’ll try to knock out least one more video blog. We are VERY busy with work here now but it all very exciting.

But for tonight let me leave you with a few more links to some videos I’ve made:

Another video tour of the JR. During the filming of the prior clip of the F-deck, we spotted a cargo ship off the port side. This is what happens any time something different happens, be it whale, seal, porpoise, cargo ship, sunset… anything.

A walking tour to the bridge deck from the F-deck. We had to ask a question of Captain Alex, and I’ll see if you can guess the answer: How far can you see out on the horizon from the main deck? From the Bridge deck? Maybe I’ll get the Captain to explain how he arrives at his answer to this question on video later! He got called away to important business. You may notice there is a lot of magic on this ship…

This is the place where the cores first enter the labs. Lots of testing, imaging, poking, prodding and sampling take place on this deck. I’ll get into more detail soon, and show some of the indigenous scientists in their natural habitat.

A quick interview with Ivano Aiello, one of the sedimentologists on board the JOIDES Resolution for Expedition 323. He explains a bit about one of the things we are looking at (micro fossils in the sediments), and how they help us understand paleoclimate.

Sedimentologist Beth Caissie shows off the Core imaging camera and explains a bit about cleaning up the cores before making these images. Taken on the JOIDES Resolution during Expedition 323 to the Bering Sea.

ABOARD THE RVIB N. B. PALMER, ON THE SOUTHERN OCEAN– We are experimenting with iron additions to phytoplankton populations to see possible effects of icebergs as a source of iron. Measuring iron and phytoplankton in the ocean is not sufficient to determine cause and effect. With that purpose, we grow cells under blue light in a freezer van maintained at zero degree Centigrade. We mimic day length (12-hours light) and water temperature (varying from -1 to +0.5 degrees Centigrade). We add iron to some bottles and others are kept without addition, as controls. The cultures are studied for several days, in our case for 2 weeks. This is enough time to determine if iron influences higher growth rate and if final cell concentrations are different among treatments.

Incubations under controlled conditions to study effect of iron addition to phytoplankton.

We are lucky that the phytoplankton growing in our cultures are the same species found most abundant in surface waters. This ensures our results are representative of what occurs in Nature and any manipulation in our experimental design is similar to what the melting of icebergs can introduce to the ocean. Fragilariopsis sp. and Corethron criophilum are the dominant diatoms. They belong to nano- (2-20 micros) and microplankton (>20 microns) respectively. Anything smaller (picoplankton or cells < 2 microns) cannot be analyzed on board and will be studied once at home.

Corethron criophilum in the cultures.

ABOARD THE RVIB N. B. PALMER, ON THE SOUTHERN OCEAN– After a four day trek looking for other icebergs we might want to study, we came back to continue studying iceberg C18A. Iceberg diversity and how it affects surrounding ecosystem is one of our goals. If the icebergs are delivering nutrients, one of our main hypotheses, we expect to see big changes when the iceberg is traveling in nutrient poor waters. The trick turned out to be how to find these nutrient-poor waters in the Weddell Sea. Looking at published nutrient values it seemed that the central Weddell Sea, far from the coast, could be a good possibility. From satellite pictures we speculated that B15L, an iceberg from the Ross Ice Shelf, could be in such waters.

As we arrived at 65º 28.362’ S, 40º 56.856’ W, B15L was surrounded by the biggest phytoplankton bloom we have seen on this cruise. Instead of half a milligram of chlorophyll a per liter we encountered ten! These waters did not seem poor in nutrients at all. The iceberg was large, tabular and somewhat more square than C18A but of similar size and characteristics. It would have been perfect for our studies. After taking a first look at the iceberg, many pictures, samples for phytoplankton and nutrients, we decided these conditions were not conducive to answering our questions. The ice edge was less than 100 nautical miles to the south; B15L was trapped in what is known an ice-edge bloom, one of the best studied high productive areas in high latitude oceans.

B15L as seen close to the ice edge in the central Weddell Sea. This iceberg has traveled from the Ross Ice Shelf half a continent away.

The ice edge bloom was dominated by diatoms. A high diversity showed many new species not sampled so far. Several Chaetoceros spp. were very characteristic: chain-forming species with interlocking spines.

Dominant diatoms at the ice-edge bloom close to B15L: Chaetoceros spp.

How best to continue our studies? Keep looking for a new iceberg in the middle of the Weddell Sea or go back to where satellite images show icebergs abound, the Iceberg Alley? We decided for the latter. In another 24 hours we were back to the western Weddell Sea. We decided to study C18A for a few more days; there were many unanswered questions still. So we are glad to have a second opportunity. A few things are different this time around. C18A had kept moving towards the NE and its position is now more along an East-West axis than a North-South one. We will be here for the next 3 days and sampling has already started.

ABOARD THE RVIB N. B. PALMER, ON THE SOUTHERN OCEAN– As most unicellular phytoplankton algae, diatoms usually reproduce by division. One cell becomes two after mitosis; the two new algae are called “daughter cells”. Once in a long while diatoms go through sexual reproduction. After meiosis the new daughter cells have a recombined genetic material. What brings this phenomenon? Some scientists think that the cell division (or asexual reproduction) produces silicon valves smaller and smaller until size can become a problem. Stress is another factor thought to affect reproductive strategy. Cells under unfavorable conditions for growth, when nutrients run out, undergo meiosis to increase their change of survival.

Corethron criophilum after cellular division through asexual reproduction.

The dominant diatom around the C18A iceberg is undergoing sexual reproduction. It is easy to see this process under the microscope as Corethron criophilum is large and the changes are striking. In cell division two smaller cells are seen at the extremes of the valve in cingular view, or along the cylinder. The auxospore is produced after fertilization of male and female gametes, leaving the mother cell.

Auxospore leaving a diatom frustule after sexual reproduction and fertilization.

Is the iceberg affecting phytoplankton in such a way to start sexual reproduction? Or does Corethron criophilum under stress due to diminishing light days as the fall season advances? These are questions we are asking ourselves. Detailed analysis of samples under the microscope once we are home will shed light on the first question. The importance of changing season on Corethron criophilum cannot be assessed during a 40-day cruise. Several months of study in the field would be needed. This is a question that might remain open and maybe can be answered in future cruises.

ABOARD THE RVIB N. B. PALMER, ON THE SOUTHERN OCEAN– Phytoplankton cells can become toxic under certain conditions. Still a mystery to scientists why they produce toxins, there has been a proliferation of large concentrations of toxic cells, or blooms, also called red tides, during the last 20 years. Dinoflagellates are the most common of the toxic algae. They can produce compounds that after concentration in the guts of animals that eat them can be damaging to humans consuming shellfish. Clams, mussels and oysters are well known vectors for these toxins. Large fisheries in the US coastal regions are closed during periods of toxic algal blooms.

The diatom Pseudonitzchia sp. in a chain with 3 cells. Determination of species requires analysis under a scanning electron microscope and will await return to the US. Small dots in the background are flagellates a few microns in size. Pseudonitzchia is a rather large pennate diatom, with two elongated valves, about 100 microns long. Some species form chains by attaching sideways to the next cell’s tip.

The diatom Pseudonitzchia, present in Antarctic waters, is well known for producing toxins. A large killing of birds in the Monterey area off the California coast made everyone aware of this alga. During this cruise we are collecting samples for Dr. Mary Silver at the University of California Santa Cruz who has studied this phenomenon in the world’s oceans. First thought to be only a coastal process, it seems Pseudonitzchia can be abundant in the open ocean, far from land. In this collaboration, Dr. Silver will measure the toxin domoic acid and we will provide the information on which species of Pseudonitzchia we collect and how many of the cells are found that can later be related to domoic acid concentration. In this way, Antarctic phytoplankton will be represented in the database of toxic phytoplankton species if indeed we find they produce toxins.

ABOARD THE RVIB N. B. PALMER, ON THE SOUTHERN OCEAN– C18A is a large iceberg, rectangular, shaped almost like a surf board, 18 km long and 6 km wide. It takes us about 4 hours at 11 knots to navigate around it. Working around the iceberg will keep us busy for the next week. There are eight Principal Investigators and their collaborators studying different aspects of the iceberg, the waters around it including our group that concentrates on the phytoplankton. Others measure zooplankton, bacteria, fishes, birds, chemistry, nutrients for plants and bacteria (like iron and what particles fall from the iceberg to the ocean bottom). We all share an interest in seeing how animals and plants are influenced by a large iceberg due to its melting of cold and fresh water. More information on different aspects of this project can be found at www.mbari.org/expeditions/antarctic09.

Our first study area: the iceberg C18A that formed off the Ross Sea shelf in 2003.

Corethron criophilum abounds here. This diatom is rather spectacular, a cylinder about 100 micrometers long (0.1 millimeters or 0.000394 inches) only seen under the microscope. Sometimes we can see some specs floating in the water but most times they are invisible to the naked eye. At each end of the cylinder there is a crown of spines, shorter at one end than at the other one, giving the cell an asymmetrical look. This species is most common in waters around the Antarctic Peninsula but can be found in other cold areas, like the Arctic Ocean.

Corethron criophilum seen from the side.

Corethron criophilum seen from the front. The crown of spines surrounds the valve edges.

Not much phytoplankton is present in these waters. A combination of being away from the continent or sea ice combined with the beginning of autumn could be the reason of the sparse community. To study these cells we concentrate them with a net of very fine mesh, 20 micrometers: we count them to estimate their concentration, describe their morphology, extract their cellular content for photosynthetic pigments and total carbon. When their abundance is low we concentrate larger water volumes, close to 200 Liters, or 52 gallons.

Is Corethron criophilum affected by the presence of the iceberg? Does the mixing of waters that bring nutrients from deep water favor its growth? If so, we expect to see more and healthier cells closer, as opposed to farther away from the iceberg. The iceberg itself can also bring nutrients when melting and enrich surrounding waters. We call this phenomenon “natural fertilization”. Experiments under controlled conditions with the addition of selected nutrients will help us answer this question.

ABOARD THE RVIB N. B. PALMER, ON THE SOUTHERN OCEAN– After 4 days in transit we arrived at Clarence Island near the South Shetlands. It is too windy to test our new instruments here. So we turn northeast and after 8 more hours we arrive at the C18A iceberg. This large iceberg was located by satellite images. C18A originated from the Ross Sea Ice Shelf half a continent away. Since 2003 it has traveled hundreds of miles around Antarctica. It entered the Weddell Sea 2 years ago, and it is now on its way north.

Chaetoceros neglectus collected near Clarence Island.

At Clarence Island we saw the first phytoplankton bloom of our cruise. Chaetoceros neglectus was the most abundant species. Diatoms are unicellular plants with a silica cell wall that come in many different geometric forms, thickness and sometimes with appendages. The wall has two units called valves that fit together like two halves of a pillbox, the smaller lower valve fitting inside the larger one.

Diatom’s cell wall has 2 halves that fit together like a box. Drawing from Round, Crawford and Mann, The Diatoms, Cambridge University Press, 1980.

Some are round, like in Thalassiosira sp. or Coscinodiscus sp. Others are elongated, like Fragilariopsis sp. Each cell can be seen from the top or the sides, making it sometimes difficult to recognize them. There are lightly silicified species, hard to see at the microscope, like Chaetoceros neglectus. The thickly silicified species are thick, brilliant and easily seen. Many species either central or pennate form chains that look like a necklace, or sometimes a ribbon, with each cell looking like a bead or a scale.

Thalassiosira sp. showing top and bottom valves.

Diatoms with round (group Centrales) and elongated (group Pennales) valves.

Thalassiosira sp. in chain, seen from the side.

Fragilariopsis sp. in chain seen from the side.

Why the diversity of form? Diatoms need to float in the ocean to live close to the surface, where there is light. Inside the cell there is a vacuole (looking almost like a balloon) where they can store chemicals that help them float. Increasing their wall surface also helps in flotation, thus the formation of chains. All plants survive if the grazers do not decimate them. Being large, as in forming part of a long chain, or having spines help them also to avoid grazing. Diatoms are the preferred food of the Antarctic krill, a common crustacean in these waters, and only the very large species can avoid being eaten.

I am sure we will keep seeing many different diatoms in this cruise and we will be taking pictures of them to share. As it is autumn here, many species are starting to become scarce, present special forms, or spores that help them spend the long winter. We are especially interested in seeing if some forms prefer to live close to the iceberg or if they are somehow concentrating a distance way, affected by melting ice.