AME 16:11-16 (1998)  -  doi:10.3354/ame016011

Viral lysis of Phaeocystis pouchetii and bacterial secondary production

Gunnar Bratbak1,*, Anita Jacobsen2, Mikal Heldal1

1Department of Microbiology, University of Bergen, Jahnebakken 5, N-5020 Bergen, Norway

2Department of Fisheries and Marine Biology, University of Bergen, Bergen High Technology Centre, N-5020 Bergen, Norway

ABSTRACT: In this experimental study we investigated the effect of viral infection on primary production and carbon flow in a phytoplankton-DOC-bacteria food chain during viral lysis of the phytoplankton population. The phytoplankter host-virus system used was Phaeocystis pouchetii (Prymnesiophyceae) and the virus PpV01. Viral infection allowed primary production in the cells to continue throughout most of the lytic cycle. In non-infected algal cultures, net production of DOC and bacterial biomass was low and at the end of the experiment the DOC concentration was 10 to 20%, and the bacterial biomass 0.5 to 4% of the algal carbon biomass. The amount of DOC released during viral lysis of the algal cells implies that the entire algal biomass was converted to DOC. Growth of bacteria succeeding cell lysis and release of DOC in virus infected cultures demonstrated that the net effect of the virus infection was an efficient conversion of algal biomass into bacterial biomass.

KEY WORDS: Phaeocystis pouchetii · Virus · DOC · Bacteria · Microbial food web

Full text in pdf format