Community structure and grazing of the nano-microzooplankton on the continental shelf of the Bay of Biscay

► The parameters controlling the nano-microzooplankton on the southern continental shelf of the Bay of Biscay were studied. ► The abundance, carbon biomass and grazing of nano-microzooplankton were evaluated at 4 periods. ► Ciliates and heterotrophic dinoflagellates were dominant in term of biomass, highest in spring and lowest in the end of summer. ► Nano-microzooplankton was predominantly constrained by bottom-up control in spring and in the end of summer.