Aquatic Sciences Meeting, Albuquerque 2001

CS25 Organic Carbon Dynamics

Date: Wednesday, February 14, 2001, Time: 3:00:00 PM

Location: Acoma/Zuni/Tesuque

Vazquez-Dominguez, E, , Horn Point Laboratory. U. of Maryland, Cambridge, MD., USA, evazquez@hpl.umces.edu

del Giorgio, P, , Horn Point Laboratory. U. of Maryland, Cambridge, MD., USA, delgior@hpl.umces.edu

Vaqué, D, , Institud de Ciencies del Mar-C.S.I.C., Barcelona, Spain, dolors@icm.csic.es

Newell, R, , Horn Point Laboratory. U. of Maryland, Cambridge, MD, USA,

Transfer efficiency from dissolved organic matter (DOM) to heterotrophic bacteria and flagellates

The trophic role of heterotrophic microorganisms within pelagic systems depends greatly on the efficiency with which detrital organic matter is transferred through the microbial food web. DOM is transformed into POC by bacteria which is then utilized by protists, but the efficiency of these two processes has seldom been assessed simultaneously. Here we present data on the transfer efficiency from DOM to heterotrophic nanoflagellates, in samples from a variety of coastal marshes and estuarine waters. The biomass of bacteria and heterotrophic flagellates, DOC, POC and inorganic and organic N and P were followed in regrowth experiments lasting 1 week. On average (±std. err), 11.8 (2.1)% of the initial DOM pool was utilized during the first four days of the experiment. Bacterial and flagellate growth efficiency averaged 12.2 (2.5)% and 15.8 (4.3)%, respectively. Approximately 1.0 (0.3)% of the DOM consumed by bacteria was converted into flagellate biomass after 4 days. The overall transfer efficiency from the DOM pool to HNF averaged 0.09 (0.01)%, and there were no consistent patterns in the transfer efficiency among systems or along nutrient gradients.

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Aquatic Sciences Meeting, Albuquerque 2001

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