Redefinition of cell size classification of phytoplankton – a potential tool for improving the quality and assurance of data interpretation

To date, phytoplankton cell size classiication is based on linear metrics (nano: 2-20 mu m; micro: 20-200 mu m; macro: >200 mu m) although three-dimensional metrics are used for cell or body size descriptions of all terrestrial and aquatic organisms. This study proposes a redeinition of phytoplankton size classiication expressed in terms of cell volume (mu m(3)) metrics by analyzing statistically a data set of 397 species from three major groups of eukaryotic taxa (diatoms, dinolagellates, coccolithophores). The three size classes based on cell volume metrics are nanoplankton (10-10(3) mu m(3)), microplankton (10(3)-10(6) mu m(3)) and macroplankton (10(6)-10(9)mu m(3)). Size spectra of cell volume frequencies, species richness-cell size and cell abundance-cell size relationships were evaluated with the use of cell volume (mu m(3)) metrics while fitting of the relevant equations signiicantly accounted for the data. The analysis of size classes versus taxonomic composition based on cell volume metrics revealed taxonomic group (diatoms, dinolagellates, coccolithophores) differentiations in nano-micro-macro size classes, thus providing an accurate size classiication within and among taxa. This classiication offers more precise information on the taxon-size relationships, which are valuable for phytoplankton community structure studies and useful for further development of the remote sensing models designed for differentiating phytoplankton taxa by satellite.