27 December 2007 - 3 January 2008

5378.9m water depth –what a pressure! On 29 Dec we reached the northernmost station of the 3 W transect at 62°S; it was the longest so far. 50 hours and 13 minutes at nearly one geographical position trying to sample the same spot in more than 5 km water depth. In preparation for the long working hours, intensive use of ship time to lower and retrieve the instruments and valuable deep-sea samples, the ship’s scientists buzzed around like a stirred swarm of honeybees. But before all the deep-sea benthos gear (benthos originates from ancient Greek meaning bottom) was deployed, bringing up the well expected fine mud that spread all over the ship’s deck and may enter every pore of our floating home, sampling in the very clear water column took place. One goal of the expedition is the identification and quantification of links in energy and matter transport from the ocean surface to the deep-sea. As ice is melting fast these days, the plankton bloom in the water starts growing and some of the freshly produced material as well as older substances from the melting sea ice have already been found sinking down. At the deep-sea floor, however, the entire community seemed to be still dormant, meaning in late winter resting condition.

The entire community? No, not quite true. Some creatures are highly active all the time. Attached to the free-fall Lander, which I described in the weekly report No. 2, were three animal traps, much like fish traps but smaller. Inside awaited a fresh but dead fish the scavengers that would enter the traps through funnels narrowing the exit holes as much as possible. And they came, in numbers above 500 in one trap. Amphipods (you might know the group from fresh water creeks) of different sizes and kinds, most of them only one or two centimetres long but some up to 8cm, squeezed in and skinned the fish to the bones within one day. One could see the swollen bellies of the amphipods probably doubling their weight by this meal. Who knows, how often they can experience such a feast, deep down where they live very close to the sea floor. Both the lower traps 30 cm above the bottom showed a high catch whereas the trap 1.5m above the seabed caught no animals at all. The electronic instruments on the Lander were less successful. One of the three electric motors driving the electrodes into the soft sediment leaked water. And seawater is very corrosive especially in combination with electricity. The scientists and the ship’s specialists have a hard time still trying to repair all the damage.

Talking about soft sediment. All the corers that were deployed sank deep – too deep into the soft bottom. The rate of sediment accumulation on the abyssal plains is rather low but nevertheless the water content of the mud is very high. Instead of undisturbed surfaces, more than full cores from the Multicorer and the Boxcorer were retrieved, much to the discomfort of all the groups working directly with biology or geochemistry at the sediment water interface. The best is, that we now have 50 cm deep sediments of considerable age. 1 cm of sediment layer represents about 1000 years.

Two other instruments were more successful, the Agassiz trawl and the epibenthic sledge. The Agassiz trawl is basically a 3 m wide 1 m high steel frame with a net attached to it. Towed behind the slowly steaming ship (1 knot trawling) it slides over the ground and collects all objects located on or just underneath the sediment surface into the strong net. After nine hours’ trawl (8000m cable had to be put out to bring the instrument down to the ground) 2 tonnes of muddy sediment squashed on deck. Soon the orange-coated scientists became muddy-grey, as was every corner on the aft deck. Load after load was shuffled into the sieves and rinsed with washing water until buckets full of strange looking creatures ended up under the microscopes in the labs and cool containers. The mud has a big advantage, as it protects the ultra fine body structures of the animals while they are on their way up through the water column. The sorting is not finished while I am writing and happy taxonomists take discs full of pictures of every morphological structure.

The epibenthic sledge also slides on the sea floor, but is equipped with two small sized mesh nets, one in 33 cm high and one at 1 m above the ground. The front bar steers up creatures and sediment that end in the two nets whereas larger (drop) stones pass underneath. Also the mesh size of 500 µm is much smaller compared to the Agassiz trawl. So the species collected by this instrument are in principle much smaller also, but this difference was not so obvious during this particular deep-sea station, as in muddy sediments all animals were well contained.

Good planning and hard work pays off. Everything worked out smoothly, gear after gear went down and came up again and in the end, station work was finished by 2 pm on December 31. The next station at 3° E was 20 hrs steaming away, just the time to celebrate the New Year 2008. The kitchen had created meals again beyond our imagination. Two roasted piglets, shining brown and soft in taste were looking at us at either end of a 10 m long buffet. Various salads (how did the cooks manage to keep the green so fresh since November?) accompanied by freshly baked bread, cheese, various other meats, and a fair selection of desserts started the glorious evening. In Germany it has already become a tradition to watch the black and white movie of the sketch “Dinner for one” during this particular evening, so we did, and laughed with gags most of us know now by heart. I remember watching this movie as a child myself. Sparkling wine on the bridge at midnight and big hugs to all. Just in time a soft rounded iceberg passed the ship reminding us of what I call the two scenic species of bergs – the females and the males. The females with the long experience of dealing with the sea, its historic memories of passed events and the home of many penguins sitting travelling in the rolling ocean. The males stick out, strong as it seems with stiff cliffs and sharp edges just to show that they don’t care about the environment that finally will overcome them anyhow.

In the engine control room we found another happy party, the one of engineers was greeting the shy scientists who seldom enter the lower interior power centre of the ship. But this was not all. Two persons on board had their birthday on 1 Jan. So with these celebrations we started dancing until the early morning. By 10 am on New Year’s day station work started again, not just as easy as usual, but not less successful.

We all hope, that you also had a nice beginning of 2008. We are working strongly on our way south again at 3°E, hoping to finish this transect by January 9 or 10.

All the best to all of you
From a still busy ship
Uli Bathmann