Lake Peipsi 2014 (Phytoplankton samples)

Method: Phytoplankton samples were preserved in Lugol’s (acidified iodine) solution and counted under an inverted microscope (Utermöhl, 1958). 3 ml of preserved sample was settled overnight and counted in random fields or transects. Biovolumes of algal cells, colonies and/or filaments were calculated using assigned geometric shapes dimensions, and converted to biomass assuming the specific density of 1 g cm-3 in accordance with Edler (1979). Approved by CEN on 14 July 2006 “Water quality - Guidance standard on the enumeration of phytoplankton using inverted microscopy (Utermöhl technique)” (CEN 15204, 2006) European Standard EN 15204:2006 Utermöhl, H., 1958. Zur Vervollkommnung der quantitativen Phytoplankton-Methodik. Mitteilungen der Internationale Vereinigung für Theoretische und Angewandte Limnologie 9, 1- 38. Edler, L. (ed.), 1979. Recommendations on methods for marine biological studies in the Baltic Sea. Phytoplankton and chlorophyll. Baltic Marine Biologists WG 9.