PS96 Weekly Report No. 7 | 25 till 31 Janauary 2016

Research final

[01. February 2016] 

Each brilliant movie, fireworks display, symphony or football World Cup tournament (at least from a German point of view) ends with a great final. At the end of the station work everybody and every team is showing off and demonstrating what they are capable of, also on this expedition. All gear used for marine science is deployed (one by one, not simultaneously!). You must have experienced yourself the complexity of deployments and techniques and the variety of results to appreciate this. The selected photographs attached to our letters only can give you a glimpse...

 

 

The first step of scientific work usually is the accurate documentation of the subject of interest. Today, nearly each sampling gear or probe is equipped with a camera for photography/video footage so that the sample is taken in full sight of the seafloor context. Some equipment is deployed exclusively for photographic mapping of previously unknown regions. Here, we are doing something against the statement “We know more about the backside of the moon than about the seafloor on Earth”.

The OFOS (Ocean Floor Observation System) is hanging on a wire just above the seafloor while the ship is drifting slowly into a particular direction. In this way we have taken several thousands of sometimes colourful photos showing the whole variety of life thriving at the seafloor. The ROV (Remotely Operated Vehicle) is a remotely controlled, water-tight robot which is connected via a fibre-optic cable, acting as its “umbilical”, to the ship and which is capable of taking samples and carrying out measurements at pre-selected seafloor locations with its powerful arm. You have to dig deep into your subject of scientific interest to find out how nature enables organisms, such as siliceous sponges, to live to a great age (up to thousands of years?) in ice-cold eternal darkness, and from where the sponges source their glass-wool like construction material (silica) as well as their food. At a water depth of 300 m it is not a good idea to try and carry out these analyses by yourself. ROV and OFOS provide us with high-resolution, state-of-the-art digital footage.

Fig. 1: Catching fish in Antarctica can be disillusioning - but is is exactly this kind of fish that is interesting for the scientists. Photo: AWI. (Photo: hannes.grobe @awi.de)
Fig. 2: Seafloor at the continental shelf break (water depth 250 m). The photo shows examples of various organism groups, including siliceous sponges, corals, bryozoans, brittle stars, anemones. Photo: Dieter Piepenburg (AWI). (Photo: Alfred Wegener Institut)
Fig. 3: Fragile artworks made by nature – bryozoan colony and sea urchin – recovered unharmed from the Antarctic continental shelf with a bottom trawl. Photo: AWI. (Photo: hannes.grobe @awi.de)

And then there is the wet lab, which fully deserves its name. Nearly everything is possible here, and this is also the reason why the rest of the ship is a “no-go area” when you are still wearing your shoes used in the wet lab. Far too rarely the geologists are taking care here of their beautiful grey plastic liner sections filled with sediment. Occasionally, an orange army of scientists in waterproof clothing invades the lab and sorts out carefully the most recent catch. No organism remains unattended, and even animals living and breathing in the sediments find themselves in the focus of the researchers’ spot light. Sedimentary sequences are “salami sliced” into thin layers and washed through sieves to get hold of those digesting even the last remains – the eatable fragments settling from the waters above down to the seabed. Excerpt from a Senckenberg book for children explaining the deep sea: “In case you have a garden at home, you may have had a look at the soil dug up with a shovel. Then you must have seen earthworms, beetles, snails...”. If you replace “shovel” with “multicorer”, “soil” with “sediment” and “earthworms” with “meiofauna”, then you will recognize what it is all about. The reuse of material within the seabed, the recycling of life, transfers nutrients back to the start of the food chain.

Fish (even without chips) is a popular component of dishes. On “Polarstern”, fish is served (not only) on Fridays. However, what our fish trawls on this cruise recovered so far, was not even enough for an appetizer in a posh restaurant. The freshly caught fish is not fried but analysed for those pollutants that were invented, used, distributed and eventually forbidden by our civilisation (e.g., DDT, PCB, PBDE, dioxin etc.). These substances were distributed globally by high-altitude winds, and the sensitivity of modern analytical instruments allows their detection even in Antarctic snow and in the aforementioned fish. Many pollutants are toxic, and therefore these substances are harmful to the organism, which responds when exposed to them with stress, sickness and, in the worst case, death. In our ship-board laboratories an entire sequence of analytical processes is set up to investigate the reactions of the immune system and its “executives” (leucocytes, liver) within the fish at the scale of an individual cell. Next week the fish biologists urgently need another trawl because all the species caught previously have now provided them with cells, and other fish relatives are required for additional analyses.

However, time for trawling collides with time for coring. In one area the geologists have discovered extraordinary seafloor structures with their echo sounders. If glacial ice is unsure what to do and neither floats (= ice shelf) nor grounds (= glacier, ice stream or ice sheet), it may just gently touch the seafloor, thereby depositing and piling up the rocky debris, which it carries at its base, in form of a characteristic feature with the scientific name “ Grounding Zone Wedge”. Because previously such features, as pristinely preserved as here, have been observed only very rarely, the geologists know exactly what they want: Two gravity cores, please! The time for the travel to Punta Arenas is clicking – other sediment coring stations are cancelled for the sake of these two cores. A dozen different research projects want and should get the ship-time they bid for...

...on our ‘Swiss pocket knife’ ship: research platform, icebreaker, cargo carrier, supply vessel, meteorological observatory, fish trawler, hotel (including wellness facilities), ambulance, air field, small power plant...Unbelievable! And everything works as well as on day one of the cruise, thanks to the excellent maintenance carried out by the Laeisz shipping company and the Lloyd dockyard.

This ship sets a high standard for the constructors of “Polarstern’s” successor.

 

Crew and science party send their greetings while leaving Filchner shelf and southern Weddell Sea behind them.

 

PS: “Spritzfisch” and “Armfüßler” secretly meet behind one of the winches and discuss baptism rhymes for “Fächerkoralle” and “Pilotfisch”. What is the meaning of that...?

Contact

Science

Michael Schröder
+49(471)4831-1821
Michael.Schroeder@awi.de

Scientific Coordination

Rainer Knust
+49(471)4831-1709
Rainer Knust

Assistant

Sanne Bochert
+49(471)4831-1859
Sanne Bochert