Journal of the Marine Biological Association of the United Kingdom

Bacterial growth response to copepod grazing in aquatic ecosystems

Cristian A.  Vargas a1a4c1, L. Antonio  Cuevas a2p1, Humberto E.  González a2a3a4 and Giovanni  Daneri a2a4
a1 Aquatic System Unit, Environmental Sciences Center EULA, Universidad de Concepcion, PO Box 160-C, Concepcion, Chile
a2 Centro de Investigaciones Oceanográficas en el Pacífico Sur-Oriental (COPAS), Concepción, Chile
a3 Institute of Marine Biology “Dr. Jürgen Winter”, Universidad Austral de Chile, PO Box 567,Valdivia, Chile
a4 Patagonian Ecosystems Research Center (CIEP), Bilbao 449, Coyhaique, Chile

Article author query
vargas ca   [PubMed][Google Scholar] 
cuevas la   [PubMed][Google Scholar] 
gonzález he   [PubMed][Google Scholar] 
daneri g   [PubMed][Google Scholar] 


The growth rate response of bacterial communities to the potential increase of dissolved organic matter (DOM) produced by the copepod Acartia tonsa was assessed in experiments conducted in three stations representing three contrasting aquatic environments (coastal embayment, shelf and ocean). Bacterial assemblages were inoculated in filtered seawater where A. tonsa had previously grazed. Utilization of DOM over time was evaluated after the addition of bacterial inoculums as the biomass changes in both ‘control’ and ‘copepod’ treatments. In the embayment and ocean a high bacterial growth was observed in the treatments with seawater where copepod were feeding. Additional field measurements of bacterial, primary production and zooplankton biomass support the idea that bacterial communities living in oceanic environments can be efficient to utilize the newly available substrate. Copepods play a key role not only as conveyors of carbon up through the classical food-web, but also generated significant amounts of bacterial substrate in the microbial loop food-web.

(Received October 31 2006)
(Accepted February 27 2007)

c1 Corresponding author, e-mail:
p1 Department of Biology, University of Bergen, Jahnebakken 5, N-5020, Bergen, Norway