I would be interested, too. Maybe it would be possible to post a summary of answers (if there were any) to the list? Thanks Sergine The only question I can answer is the last one : you need approximately 1mg for the analysis. Maybe a ittle bit less could do, the best is to discuss this with the person in charge of the spectrometer on which you will perform the analyses. For the rest, I think it depends very much on the question you want to ask. Of course diet can change the d13C, but also relative inorganic carbon content if you compare different species (you may acidify your samples to control for this), etc. I think there is no simple answer to your questions about factors that may affect d13C in zooplankton, you have to read about it and see whether the magnitude of the variations likely to arise because of "parasite" factors are likely to be large compared to those due to the factor you would like to study... Sorry not to be of more help. Sergine >Have you got some answer? >I'm interested too. >Thanks in advance >Veronica >-----Messaggio originale----- >Da: Theodory R G <[log in to unmask]> >A: [log in to unmask] <[log in to unmask]> >Data: luned́ 30 agosto 1999 22.42 >Oggetto: D13C IN ZOOPLANKTON > > > >Dear list members, > > I'm working with a predatory zooplankton species. Should I expect > >different d13C values for the same species at different sites within the > >same lake? Could a different diet at each location enrich or deplete the > >d13C of the species? Are there other factors such as depth, temperature, > >discharges from sewage treatment plants, or d13C of DIC that could affect > >d13C? What would a variation in sulfur isotope composition of the species > >in different areas tell us? > > My other question deals with the procedural aspects of handling > >the zooplankton samples after collection. Is it as simple as freezing > >then drying the samples before analysis? And, finally, how many > >milligrams of the zooplankton sample would be sufficient for isotopic > >analysis? > > Any help or references would be greatly appreciated. Thank you in > >advance. > > > >Cheers, > >Ronnie > > Sergine PONSARD laboratoire d'Ecologie des Populations et Communautes UPRESA 8079 Batiment 362 Universite Paris XI 91 405 Orsay Cedex France Tel : 33 1 / 69 15 56 91