The Mesocosms

For the 2010 campaign we will be studying the impacts of ocean acidification on biological and chemical processes that go on in the water column. We will do this by running a CO2 enrichment experiment using the newly developed KOSMOS system (Kiel-Off-Shore-Mesocosms for future Ocean Simulation) in the Kongsfjord off Ny Ålesund, Svalbard. For this we will deploy nine 8 m high and 2 tons heavy floating frames (see figure 1). These frames are about the same height as two double-deck buses stacked on top of each other, and as heavy as a small car!

The frames contain 17 m long flexible bags which will enclose a column of water of approximately 40 cubic meters each. These bags will be lowered from the surface through the frame structure, after the frames are deployed and secure. Each bag can be closed off at the bottom. These bottom shutters will be closed off by divers. Once we are happy the mesocosms are secure then we will bein a step-wise acidification of the enclosed water body using gaseous CO2, which we will bubble into the bags. We aim to achieve a range of CO2 concentrations from present values (~385 ppm) to values expected for the middle of the next century (1000 – 1250 ppm).

Fig. 1: Drawing of the mesocosms with the 17 m long bags extended inside the 8 m high frames, which float at the water surface.

For the following 5 weeks scientist from many disciplines, including ocean and atmospheric chemists, molecular biologists, marine biogeochemists and ecologist, will sample the mesocosms daily from zodiacs and analyze their samples in the laboratories of the Ny Ålesund Research Station. They will monitor the enclosed seawater and plankton community to learn more about the biological responses to ocean acidification and understand what consequences these have for community development, biogeochemical processes and air/sea gas exchange.

Figure 2: Floating mesocosms being tested of Kiel, Germany. Photo courtesy of Ulf Riebesell.

Figure 3: Taking samples at one of the mesocosm bags from the zodiac during testing in Kiel, Germany. Photo courtesy of Ulf Riebesell.

Figure 4: Up close sampling at one of the mesocosms during trials in Kiel, Germany. Photo courtesy of Sebastian Krug.

Figure 5: Sunset over the mesocosms during testing in Kiel, Germany 2009. Photo courtesy of  Michael Sswat.

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