Menden-Deuer, S. University of Washington,
Lessard, E. University of Washington,

In order to quantify and compare the roles of different planktonic organisms in food web models and carbon budgets, cell abundance usually is converted to carbon and nitrogen weight. The cellular C content and C:volume ratios have been determined experimentally for most major planktonic groups. However, no general C:volume conversion factor exists for dinoflagellates, a nutritionally and morphologically diverse protist group. We measured the cellular carbon content and volume of a large number of thecate and athecate, heterotrophic and autotrophic dinoflagellate species. Since plankton samples are usually analyzed after fixation we investigated the effects of fixatives on cell volume estimates. We also compared volume estimates made using geometric formulae and linear measurements with those estimated from 3-D images using deconvolution microscopy, as cell volume is a critical but difficult parameter to estimate accurately. C:volume ratios ranged from 50 - 300 fg C Ám-3 and varied with size and nutritional mode. The ratio decreased with increasing cell volume and heterotrophs were less carbon dense than autotrophs. Response to fixation with Lugol's and glutaraldehyde was species-specific. These results provide data to more accurately assess the significance of dinoflagellates in planktonic food webs and biogeochemical cycles.
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
Code: SS38WE0640S