IMIS

This dataset was compiled from a historical collection of phytoplankton datasheets. These data sheets were used as a protocol for phytoplankton sampling and analysis. They provided information about the metadata (sampling transect, station number, coordinates of the sampling station, sampling depth, sample collection date, name of the researcher who processed the sample, etc.); the equations used to calculate the abundance of phytoplankton species; and data (identified species, cells counted in the subsample, total abundance, and total biomass). Samples were concentrated by sedimentation and surface water removal to increase the phytoplankton density in the sample by following the standard sedimentation technique for sample preparation (Morozova-Vodianitkaia, 1954). After the volume of the concentrated sample was measured, a subsample of 0.1 ml was taken from the concentrated sample, poured into the counting chamber, and analysed under an inverted microscope, in order to identify and count all the phytoplankton species. Phytoplankton abundance per litre was calculated by the following equation: N = V1/V2 x n x 2, where N is the number of cells per litre of water, V1 is the volume of the concentrated sample, V2 is the volume of subsample, n is the number of cells counted in a subsample and 2 is the multiplication factor (Morozova-Vodianitkaia, 1948; Bodeanu, 1987 - 1988). The phytoplankton biomass was determined based on morphometric measurement of phytoplankton units. The biomass of phytoplankton per cubic metre of water was calculated by multiplying the abundance with the average wet weight of the species, following the average weights tables elaborated by Morozova-Vodnițkaia (1948; 1954) and Pițîk (1950), modified and updated by Bodeanu N. and Ruță G. (1995).