Studies of nano-microzooplankton dynamics based on the analysis of community taxonomic composition are highly time consuming and manpower demanding. Recent developments in automatic plankton counting technology are offering a new way to consider plankton dynamics with straightforward analysis of community size structures. The present study aimed to ensure that size is a good descriptor of nano-microzooplankton dynamics. The dynamics of the nano microzooplankton community of the Bay of Biscay (France) over three sites and four sampling periods was analyzed using three different parameters of classification: taxon, body size (ngC cell-1) and equivalent spherical diameter (µm). A Mantel test revealed that there was no difference in the characteristics of nano-microzooplankton dynamics when studying either community size structure or taxonomic composition. Moreover, a BEST test confirmed that the biotic and abiotic factors selected for impacting nano-microzooplankton community dynamics were the same among the three classification types. Considering those results, it was argued that nano-microplankton dynamics is well defined by the study of the community size structure. While focusing on nano microzooplankton size structure seems promising, homogenizing the size descriptor used among studies would be needed in order to make worldwide data comparisons and ESD/biovolume should be favored.