VARIATIONS IN MORPHOLOGY AND QUANTITY OF VIRUSES AND BACTERIA IN VILLEFRANCHE BAY, DURING TWO SUMMER WEEKS <B>VARIATIONS IN MORPHOLOGY AND QUANTITY OF VIRUSES AND BACTERIA IN VILLEFRANCHE BAY, DURING TWO SUMMER WEEKS</B> <HR><P> Børsheim, K. Y. & Karner*, M.<BR> Laboratory of Biotechnology, The Norwegian Institute of Technology, N-7034 Trondheim<BR> *Station Zoologique, B. P. 28, F-06230 Villefranche sur Mer, France</B><P><P> Bacteria and viruses were investigated using transmission electron microscopy of samples concentrated quantitatively on grids using ultracentrifugation. The samples were collected daily from 1 m depth during two weeks in June 1994, from "Point B", located at the entrance of Villefranche Bay, France (43(o)41'10''N, 7(o)19'00''E). Previously, nanoplankton annual variation in bacterial biomass has been estimated by other members of the MEDIPELAGOS group, using weekly sampling and epifluorescence light microscopy. The purpose of the present study was to investigate the smallest plankton on a finer time scale and size scale. Day to day variation of virus concentration was profound. The bacterial morphologies showed large diversity, with a numerical prevalence of extremely small cells of vibrioid or spirillar shape. <P><P>