New Insights into Role of Southern Ocean in Global Climate System
08.02.2008 - Logistics, Other
The recent Polarstern expedition was dedicated to organisms and materials cycles in the ocean. Among other topics, a team of 53 scientists from 9 countries have been studying the biological carbon pump in the Southern Ocean. There, large quantities of surface-drifting plankton algae are able to significantly reduce the carbon dioxide content of the surface waters, which can affect the global carbon dioxide cycle.
Plankton algae from the Antarctic Circumpolar Current and the Weddell Gyre, two marine currents South of the Atlantic Ocean, are absorbing significant amounts of the climate gas carbon dioxide through their growth during the summer. By sinking to the Antarctic deep sea, these algae are subsequently transferring the carbon dioxide to the seafloor, where, in some cases below 4000 meters in depth, they provide food for bottom dwelling organisms.
In order to investigate the complex interactions at work in this biological carbon pump, Scientists had a close look at an algal carpet of approximately twice the size of Germany in order to find out which physical conditions lead to such algal blooms, and how these blooms affect their living and non-living environment. For the first time ever the complete water column of the Southern Ocean - from the surface to the seafloor - was sampled simultaneously and comprehensively.
Various studies conducted aboard Polarstern during this expedition were part of large international programmes within the International Polar Year framework:
- The research programme SCACE (Synoptic Circum-Antarctic Climate and Ecosystem Study) explores physical and biological interrelations in the Antarctic Circumpolar Current, comparing recently recorded parameters with historical data. One of the central tasks of the SCACE programme consisted in collecting a unique data set that can serve as a benchmark for comparison with existing data in order to identify and quantify polar changes.
- The LAKRIS project (Lazarev Sea Krill Study) is a detailed investigation into the life cycle, distribution and physiology of krill populations in the Lazarev Sea. This study complements similar large-scale investigations in other regions of the Antarctic by highlighting the special role played by krill in food webs found in the Southern Ocean.
- The ANDEEP-SYSTCO project (ANtarctic benthic DEEP-sea biodiversity: colonisation history and recent community patterns - SYSTem COupling) tried to shed light on Antarctic deep sea environments, far less well known than their continental counterparts. The primary goal of this project is the analysis of interactions among atmosphere, water column and seafloor. The Polarstern expedition was also part of two major global research initiatives studying marine biodiversity: the "Census of Antarctic Marine Life" (CAML), and the "Census of the Diversity of Abyssal Marine Life" (CeDAMar), both of which are sub-programmes of the so-called "Census of Marine Life".
