IGB LakeLab

Description of the infrastructure: The LakeLab in the deep clear-water Lake Stechlin, NE Germany, consists of 24 cylindrical enclosures encompassing large water volumes of 1270 m3 (9m diameter, 20m depth) each. The special features of the LakeLab are the unique combination of large size and number of mesocosms enable multi- factorial designs and new research perspectives, including testing of large instruments and calibration opportunities (e.g. remote sensing) not possible in most mesocoms. Further, flexible curtains attached to aluminium floats extending into the sediment enable experiments on benthic-pelagic coupling also during winter, including manipulation of ice and snow coverage. Water renewal by special high-throughput impeller pumps (100 m3/h) minimise disturbance of plankton and provide excellent tools to manipulate mixing regimes and stratification patterns. Gases (N2, CO2, CH4) and solutes can be injected in air-lift systems, whereas application of xenobiotics or introduction of foreign species is precluded. All 24 units of the LakeLab are equiped with automated sensors mounted on vertical profilers recording water-quality parameters at high-resolution: PAR, pressure, temperature, pH, conductivity, O2 and fluorescence-derived biomasses of 4 algal groups and total phytoplankton. Four identical profilers are deployed in the lake at the LakeLab. All profilers are controlled by industrial computers collecting and transmitting data in real-time to a central data base server. The LakeLab is in close proximity to well-equipped laboratories of IGB’s Department of Experimental Limnology, located directly on the lakeshore. Quick boat access (<5 min) to the laboratories facilitates prompt analyses of delicate live samples. Laboratories include radioisotope lab (14C,3H,33P,35S), molecular S1 labs, walk-in climate rooms, and standard labs. Analytical instruments include autoanalysers for nutrients, ion chromatograph, UV-Vis spectrophotometers, fluorospectrophotometer, fluorimeter, TOC/TON analyser, CNHS analyser, CaCO3 analyser, GCs, HPLCs, ultracentrifuge, flow cytometers, FlowCAMs, picture based flow cytometer, zooplankton scanner, software for picture recognition and machine learning approaches, scanning electron microscopes, bright-field, epifluorescence and inverted microscopes, image analysis systems, other standard laboratory equipment and field gear (multiprobes, plankton nets, sedimentation traps, sediment corers, layer sampler, underwater video system, underwater microscope). The long-term monitoring programme on Lake Stechlin provides background data on water chemistry, phyto- and zooplankton, fish, primary and bacterial secondary production. Meteorological data are recorded by the German Environment Agency on site.