ANT XVIII/5b: Krill biology
Southern Ocean GLOBEC

Weekly report 1, 17.04.2001

FS POLARSTERN left Punta Arenas at 08:00 last Saturday -12 hrs later than expected-carrying 47 scientists representing 8 nations and 44 crewmembers. We used the previous day for unpacking and setting up our equipment. As soon as we left the Chilean channels, POLARSTERN headed south while westerly winds of Beautfort 6 started to roll the ship. Most of us very quickly adapted to a life in a moving environment where gravity not longer has only one direction.

Our expedition is part of the international programme "Global Ocean Ecosystem Dynamics" (GLOBEC) which relates the biology of key species in the marine plankton with ocean physics. Accordingly our team consists of physical and biological oceanographers with an interdisciplinary approach to such scientific questions. Our work is co-ordinated internationally and American scientists will continue and supplement our research during the next months. Two US research vessels will also approach Marguerite Bay west of the Antarctic Peninsula, as this was selected as one of three study sites for Southern Ocean GLOBEC.

The key species for SO-GLOBEC is the Antarctic krill (Euphausia superba). During the last few years, krill have become important again for human utilisation as modern fishing techniques have overcome the problem that krill meat (protein) quickly degrades due to the enzymes present in the gut. These enzymes in turn have become important in modern medical treatments of cancer, gangrene and others. In addition fluorine is enriched in the chitin of krill so that the carapace has to be separated from the meat before it can be used as food.

As a key species, krill is preyed upon by many whales, seals, fish, penguins and other birds. An Australian-Dutch team will be looking into this by standing outside all day long on the upper bridge. Krill are highly flexible predators, feeding on plankton (organisms which float in the ocean), animals living at the sea bed or in sea-ice. We do not know exactly which of these food items the larval and adult krill feed on during autumn and winter, and thus this is one of our main questions.

Over-wintering of krill seems to be closely linked to the extent of sea-ice. How krill is adapted to the sea-ice habitat will be investigated during our cruise by a team of sea-ice biologists, scuba divers and by means of a remotely operated vehicle. In addition we will perform experiments in our 6 experimental containers run at in situ water temperature. All of these investigations will be explained in more detail in later reports. Our work is meant to accumulate knowledge essential before any predictions on the effect of krill fisheries in Antarctica are possible.

During Easter the Southern Ocean was awaiting us with bad weather and cold winds, no wonder: austral autumn approaches. Soon we will be in Antarctica and we are looking forward to have our first sampling station at the continental slope west of Adelaide Island.

With many greetings from the ship board party,

Uli Bathmann (chief scientist)