Week 5 — 27 Dec 2007-2 Jan 2008

27 December 2007

Saskia Brix, Senckenberg

Secrets of deep-sea isopods

We are happy. Happy about our successful first step on the way of teasing secrets out of freshly caught deep-sea isopods from 3000 m depth. Which means, we have extracted DNA and after the first successful runs prepared extractions all day long, highly motivated. How we got there.

After META, our epibenthic sledge, had brought the samples for us on deck, we divided the sample immediately by weight and live-sorted one-half in the cooling container at 0°C and preserved the other half in precooled alcohol at -20°C. While live sorting we got a first impression of the creatures that awaited us: bristle worms (Polychaeta), amphipods, several forams and, among many other taxa, our target group, the isopods (by then we were exhausted but happy!) The individuals picked in the cooling container were fixed in RNAlater (a special solution to store DNA) or shock frozen at -80°C. These animals we want to work up later to compare the suitability of both fixation methods for genetic studies.

After that we had to wait 48 hours before we could sort the alcohol-fixed samples. A test of our patience, as we were very curious what would be hidden in the deep-sea mud... During the sorting some 200 isopods of many shapes and forms were discovered. Each individual is photographed and catalogued. This is our first contribution to the ‘Barcode of Life’ project ‘Barcoding CeDAMar Isopoda’. Our work focuses, aside from the barcoding aspect, on certain families whose relationships we want to reveal with the help of genetic methods. And of those families, we already found several individuals in the samples!

In a second step, we steal three to four legs from each isopod (out of 14 legs or 7 pairs of legs which isopods possess.) This is not a trivial task, considering how minute isopods are (1-10 mm). The biggest challenge is to transfer the tiny extremities into Eppendorf vials. On a single day we worked up some 50 isopods, and the next batch of extractions is already sitting in a 56°C water bath for lysis. This was a successful day in every meanig of the word. So much for the explanation why we are so happy.
Out of a total of five strategies to process samples, we finally found the one that is successful, which will be a base for analyses at home. Now that the DNA extraction with classical kits is working, the question is, how will the RNAlater and the frozen animals work? Is there a difference between extracts from animals processed right after the catch and those fixed in alcohol? There are more revelations on the horizon.

28 December 2007

Harry Leach, University of Liverpool

An introductory course in physical oceanography

As station work on deck since Christmas has addressed mostly characteristics of the water column, this might be a good opportunity to take a closer look at what oceanographers actually do. For an average person, it is difficult to imagine that water is divided into different bodies which are characterised by well-defined parameters. This is what the oceanographers observe and measure, and the most astounding thing to a non-oceanographer is that the water bodies will remain pretty much the same over time. They will still be there when you come back next year! This is demonstrated in the two diagrams showing temperature and salinity values from two different years — 2006 and the first few weeks of our expedition — and they look almost exactly the same!

As we left Cape Town at 33°S, approaching the shelf ice edge near Neumayer station at 71°S, we crossed a number of distinct fronts where there are rapid changes in either one or both of temperature and salinity, which are measured with the thermosalinograph: the Subtropical Front at 42°S, where temperature and salinity decrease; the Subantarctic Front at 45°S where both decrease yet again; the Antarctic Polar Front at 49°S, where the temperature decreases again; the southern Antarctic Circumpolar Current Front, with another decrease in temperature, at 53°S; the Southern Boundary of the Antarctic Circumpolar Current, indicated by an increase in salinity, at 57°S; and finally, at 59°S, the ice edge, where the temperature of the water is near the freezing point of sea water (about -1.85°C).

While the fact that the water is getting colder and colder as we get closer to the Antarctic continent seems to be straightforward, the processes causing salinity changes are rather more complicated. The Antarctic Circumpolar Current (ACC) has less saline water than the water bodies to the north and south because of freshwater coming from melting ice, but also from snow and rain from the low pressure systems which are steered along the ACC by the temperature contrast. South of the ACC is the Weddell Gyre where the surface salinity is higher again because it is here where salty, heavy Deep Water that came from the North Atlantic rises to the surface. This is a process called upwelling, well known, for example, for the west coast of North America.

Sunday, 30 December

Brigitte Ebbe, Senckenberg

Final run 2007

Lecture room, 10 a.m. ‘Can you deploy the corer a bit faster?’ — ‘Sure, we try! One point five down is ok.’ Time is in short supply, we are nearly at the northernmost point of our western transect at 62°S. To make good use of the workfree period on New Year’s Eve, we would like to steam eastwards during that time.

That was a few days ago. The urgent requests of the expedition leader have worked wonders in the meantime. At the end of today, we are several hours ahead of schedule. The switching between the different plankton nets is running like clockwork, and when I go on deck after dinner, everything in the benthos team seems to happen all at once. At the stern a whole army of people is busy sieving about 1-2 tons of the finest deep-sea mud from the Agassiz trawl. There is a lot of shoveling, swaying and washing, and laughing eyes are looking at me from mud-smeared faces. An astonishing plethora of large animals is gathered in buckets, I see mostly sea cucumbers, but I am also told about worms and large isopods. What a difference to last night, when we ran the coring instruments, which could not handle the buttery soft sediment and came back on deck either overpenetrated or empty!

Behind the clean Agassiz trawl the epibenthic sledge is already hanging on the hook. We are just steaming to position, and then it will go on its long journey to the deep, an impressing 5200 m down. A little further to the front of the work deck another group of scientists is leaning over the bordwall expectantly. The lander is back, it has not burrowed itself in the sediment for ever, as we had feared after the experiences with the corers. Laughing faces here, too, especially that of Henri, the amphipod specialist who was so unlucky at the beginning of the expedition. Yesterday he had attached some traps to the lander, baited with fish, and now, 24 hours later, he opens them on deck to reveal fish eaten to the bones and a whole variety of very full amphipods crawling around. In the Wetlab 1 plankton samples are being worked up, and a few doors down the hallway, in the photo lab, the deep-sea video camera is being set up. It will be deployed after the epibenthic sledge to start the last day of the year.

1 January 2008

Delia Fontaine, University of Geneva

First day of the year, welcome in 2008!

This morning on the ship, the eyes were a little bit swollen, the features looked drawn, movements a were little bit slower than usual. Yes, on the Polarstern, as beautiful as the party might be (and it was!), the respite is short and the scientific work doesn’t wait very long. So, at 10 o’clock this morning precisely, the scientific activities started again. As far as I am concerned, I am lucky, the foraminifera, microscopic marine protists affectionately called ‘forams’, allowed me to sleep a little longer. Indeed, since they have been caught during the last deep benthic station, two days ago, they are stored in the sediment were they live, in a cool room at 1°C. I change their water every day, to supply oxygen and remove the decomposing organic matter.

More generally speaking, my work consists of sorting the sediment in order to pick out living specimens of forams, then identify them as precisely as possible, at least to genus but if possible even to species, and finally extracting the DNA in order to carry out genetic studies that will permit us to clarify the phylogeny and the evolution of this group.

The interests of studying the forams are numerous. It’s a highly diversified group, with more than 4000 actual species. They are very sensitive bioindicators of environmental change but they are also widely used as biostratigraphic and paleoecological indicators. The most well known have a shell, called ‘test’, whose architecture is extremely accurate and the composition very diverse (calcareous, agglutinated or organic). This last feature is usually used to make the morphological determination. More specifically, the study of the deep forams is extremely interesting, because of their high abundance in the deep benthic samples, but also because very little is known until now about the deep species and many questions are still waiting to be answered. Hopefully, 2008 will bring us some answers, but above all and because this makes science so fascinating, some new questions!

2 January 2008

Rebeca Zapata Guardiola, University of Seville

New year, new life.

Today is the second day of the year, it is cloudy and the sun isn’t shining. It’s really a grey day…But I don’t mind!! Because I’m on one of the best scientific ships, the Polarstern, making my dream reality.

This is my first cruise…and for me everything is new and exciting. I meet people from different countries, discover the German customs, get used to life on the ship, and of course learn all I can about my work!!

On board I’m working with the AgassizTrawl (AGT), a spectacular gear that provides samples for people that work with several groups of animals, from sponges to fishes. My interest…Cnidarians! Although I’m specializing in a benthic genus called Thouarella, on board I’m responsible for collecting all of them. The process to catch them is fascinating, first of all when the AGT is on deck…all seems a chaos! Lots of mud, buckets everywhere, people around…but step by step we find a way to work as well as possible.

Especially on the last station (the third on this cruise)…everybody knew what to do...and it was fantastic, a great job. I enjoyed it very much because you’re part of a team where people work to achieve the same aims, and this produced in me an indescribable feeling. Later, when deck and the gear are cleaned, you can only think of the content of the buckets…What kind of animals will be there? How many cnidarians? Now it’s time to classify, to take pictures and to fix samples…There are still some hours of work ahead… Take your coffee and keep on!!

When you finish at 4 o’clock in the morning, you need to relax. It’s time to go outside, breathe pure Antarctic air, feel the breeze in your face and look around… you’re in the most beautiful place in the world.

So the new year will bring to me a lot of  new experiences starting with this adventure.  The possibility to stay here on the ship although I’m only a student that has just started the PhD work, and to introduce myself in the world of science is a real pleasure. So now an important change is happening, I’m at the beginning of my new life.

Previous week — Week 4

Next week — Week 6

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