Eichdatensatz MV (Noth German diatom data set) Exerpt from Adler, Hübener, Anderson and Lotter (submitted for EJP): The Mecklenburg Vorpommern Dataset

The Mecklenburg-Vorpommern dataset consists of 84 lakes located in the North-German lowlands (Mecklenburg-Vorpommern) (Fig. 1). The lakes are typical kettle-type, formed in glacial till of Weichselian origin, and are well-buffered, hardwater and carbonate-rich lakes. Intensification of agricultural in the lake catchments during recent decades has resulted in more or less eutrophic conditions in the most of the lakes. For each lake, water samples were collected three times a year (spring, summer and autumn) at a water depth of 0.5 m and analysed for 19 environmental parameters using standard methods. Physical parameters (temperature, O2-saturation, conductivity, REDOX, pH) were measured with the measuring probe TORPHIL 406, version 3.0 (COMTEX). All lakes, excepting nine shallow lakes are dimictic and have surface areas >50 ha. Littoral deposits are mainly mostly muddy (stones occur only rarely) and the shores are fringed mainly by Phragmites australis.
Surface sediment samples were collected from the deepest part of the lakes using a Uwitech-corer. Approximately 2 cm3 sediment were treated according to Kalbe & Werner (1974) and diatoms were mounted in Naphrax®. Identification mainly follows Krammer & Lange Bertalot (i.e. Krammer & Lange Bertalot 1986-1991, Lange Bertalot 2001, Krammer 2002) and after counting of nearly 1000 diatom-valves at 1000x magnification (Zeiss-Axioplan, 1,4 plan-apochromat), abundances were expressed as a percentage of total count. Taxonomy of critical taxa was established using a scanning electron microscope (Zeiss DSM 960A).