NANOPLANKTON AND PICOPLANKTON GROWTH AND PRODUCTION IN THE BAY OF VILLEFRANCHE-SUR-MER (NW MEDITERRANEAN)

Rw Sheldon , F Rassoulzadegan (1) , F Azam (2) , T Berman , Ds Bezanson , M Bianchi (3) , D Bonin , A Hagstrom , M Lavalpeuto , J Neveux (4) , P Raimbault (5) , A Rivier , B Sherr , E Sherr , F Vanwambeke , J Wikner , Am Wood , Cm Yentsch

1 Station Zoologique de Villefranche
2 SIO - UC San Diego - Scripps Institution of Oceanography
3 Laboratoire de Microbiologie Marine
4 OOB - Observatoire océanologique de Banyuls
5 MIO - Institut méditerranéen d'océanologie

Plankton production in the Bay of Villefranche was relatively constant during March and April 1986 but the particle size at which the production occurred was more variable. At the beginning of the study, production was dominated by the larger (ca. 6 mum) flagellates but towards the end it was more or less equally divided between the nano- and picoplankton. There were considerable differences in the estimates of population growth rates, depending on the methods used, but on average the population doubling times were close to 12 hours for autotrophs and 24 hours for heterotrophs. As autotrophs do not grow during the night, each population was therefore doubling once per day. It seemed that each of the nano- or picoplankton populations could adversely affect the growth of the others. This could be either by simple predation or by some form of inhibition. Although nutrient levels in the bay were uniformly low, the addition of nutrients did not always stimulate algal growth. The plankton populations seemed to be both in a state of equilibrium and intense ecological competition.

Domaines: Océanographie

Rw Sheldon, F Rassoulzadegan, F Azam, T Berman, Ds Bezanson, et al.. NANOPLANKTON AND PICOPLANKTON GROWTH AND PRODUCTION IN THE BAY OF VILLEFRANCHE-SUR-MER (NW MEDITERRANEAN). HYDROBIOLOGIA, 1992, 241 (2), pp.91-106. ⟨10.1007/BF00008262⟩. ⟨hal-03476503⟩