An Experimental Platform for Climate Change Impact Research on Lakes

In cooperation with national and international partners, the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) investigates in its LakeLab how freshwater lakes respond to climate change. The unique research platform established in a natural lake consists of 24 cylinders measuring 9 m in diameter and extending to 20 m depth, thus separating water volumes of about 1250 m3 from the lake. Special plastic curtains that reach down to the sediment serve as lateral walls. They are mounted to floating aluminium rings at the water surface. A zipper system facilitates occasionally desired water exchange with the lake. Submerged pumps, pipes and perforated distribution rings that are vertically adjustable are designed to manipulate the mixing regime of the water column. Thus one can experimentally mimic the physical conditions of lakes expected in the face of climate change. Sediment traps are used to determine the sinking flux of particles. Each cylinder is equipped with a programmable profiler system, whose probes record depth profiles of currently eight standard limnological parameters: temperature, pH, oxygen, redox potential, electrical conductivity, light intensity, turbidity and chlorophyll. Additionally, a submersible fluoroprobe differentiates four large taxonomic groups of algae. The profilers are controlled by industrial computers, which also record the acquired data, provide transient storage space, and transfer the data to a land-based server via an underwater cable. An automatically updated data base on the server ensures permanent data storage.

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