Net and gross incorporation of nitrogen by marine copepods fed on 15N labelled diatoms: methodology and trophic studies - Archive ouverte HAL
Article Dans Une Revue Journal of Experimental Marine Biology and Ecology Année : 2007

Net and gross incorporation of nitrogen by marine copepods fed on 15N labelled diatoms: methodology and trophic studies

Résumé

The stable isotope of nitrogen (15N) and an appropriate three-compartment model were used in two 24-h lasting feeding experiments to trace the flow of N through the copepod Acartia discaudata and Calanus helgolandicus fed on 15N-labelled Skeletonema costatum and Thalassiosira weissflogii, respectively. Details of the labelling technique and principles of the computation of N transport rates are given. At the end of a single 24-h feeding period only about one third of the total amount of N ingested by A. discaudata was incorporated into the copepod's body N; we refer to this rate as net incorporation. Most of the N ingested was lost as ammonium (48% of total N ingested), followed by losses in the form of eggs + fecal pellets (13%) and dissolved organic N (DON, 9%). The sum of net incorporation and the latter losses is defined as gross incorporation. Net incorporation by C. helgolandicus and N losses did not vary over time during a 24 h lasting time-series feeding experiment. On average, 79% of total N ingested was actually incorporated by the copepod whereas mean N losses as ammonium, eggs + fecal pellets represented only 12 and 9%, respectively. After a 24-h feeding period only 2% of N ingested was lost as DON. Inspection of individual DON pathways showed that both A. discaudata and C. helgolandicus highly contributed to total DON production via direct excretion (79 and 64%, respectively). The remaining DON appearing in the DON pool was derived from phytoplankton via direct release and/or indirect release (copepod ‘sloppy feeding’).
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Dates et versions

hal-00482361 , version 1 (10-05-2010)

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  • HAL Id : hal-00482361 , version 1

Citer

Dorothée Vincent, G. Slawyk, Stéphane L'Helguen, Géraldine Sarthou, Morgane Gallinari, et al.. Net and gross incorporation of nitrogen by marine copepods fed on 15N labelled diatoms: methodology and trophic studies. Journal of Experimental Marine Biology and Ecology, 2007, 352 (2), pp.295-305. ⟨hal-00482361⟩
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