Aquatic Sciences Meeting, Albuquerque 2001

CS20 Microbial Dynamics

Date: Friday, February 16, 2001, Time: 9:30:00 AM

Location: Ruidoso/Pecos

Rassoulzadegan, F, , Laboratoire d'Oceanographie de Villefranche, Villefranche-sur-Mer Cedex, France, rassoul@obs-vlfr.fr

Legendre, L, , Laboratoire d'Oceanographie de Villefranche, Villefranche-sur-Mer Cedex, France, legendre@obs-vlfr.fr

BACTERIAL COMPETITION WITH ZOOPLANKTON: A CONTINUUM

The sizes of (food) resources exploited by most groups of pelagic marine organisms range between 1 and 0.001 time the sizes of the organisms. There are remarkable exceptions to that allometric rule, i.e. phytoplankton use dissolved resources (carbon dioxide and nutrients) that are smaller than 0.001 their sizes, some large microphagous zooplankton (e.g. salps, appendicularians) and large nekton (e.g. baleen whales) can feed on prey smaller than 0.001 their sizes, free viruses infect organisms larger than themselves. Another exception to the allometric rule are heterotrophic bacteria, that colonize large organic particles in the water column. The concentration of bacteria on DAPI yellow particles (DYP) is ca. 0.03 cell µm-2 for DYPs smaller than 5 µm, and falls to zero for DYPs smaller than 2 µm. Hence, bacteria compete for organic matter not only with metazooplankton (Azam & Smith 1991), but also with protozooplankton down to the size of the smallest particles efficiently grazed by the latter. As a result, bacteria shelter organic substrates in the size range between 2 µm and monomers, the latter being readily usable by bacteria.

Return to This Session's Schedule · Complete Session Listing ·

Aquatic Sciences Meeting, Albuquerque 2001

Quicklinks