Journal of Plankton Research Vol.21 no.12 pp.2323-2340, 1999
© Oxford University Press 1999
Infection of Coscinodiscus granii by the parasitoid nanoflagellate Pirsonia diadema: III. Effects of turbulence on the incidence of infection
Marine Botany (FB2), University of Bremen, PO Box 330 440, D-28334 Bremen and 1 Department of Biology, University of Konstanz, Jacob-Burckhardt Straße 25, D-74464 Konstanz, Germany
The influence of turbulence on the incidence of infection of the diatom Coscinodiscus granii by the parasitoid nanoflagellate Pirsonia diadema was investigated experimentally with two initial host densities. Independently of the initial diatom densities of 7 and 44 cells ml1, under calm conditions both diatoms and parasitoids became extinct within 69 days. Turbulence, however, led to the survival of diatoms at a reduced density of 0.12 cells ml1 for >30 days. A population-dynamic model is formulated that takes into account the non-homogeneous distribution of infecting flagellates among host diatoms. Application of the results to parasitoiddiatom interactions in natural waters suggests that, under turbulent conditions, endemic infections may effectively prevent the mass development of host diatoms.