VARIATION IN MORPHOLOGY WITH SERIAL DISSOLUTION OF COMMON SOUTHERN OCEAN DIATOMS

The global carbon budget is a topic of ever increasing importance when viewed in the light of global climate change. Most of the world's primary productivity occurs in the oceans, and 40% of the ocean's net primary productivity is contributed by diatoms. Therefore, diatoms have the potential to play a key role in carbon sequestration. In order to understand that potential, as well as the role diatoms have played over glacial/interglacial cycles in the past, an understanding of diatom productivity is required. However, in the sedimentary record, diatom production is altered by variable preservation over space and time. This study presents the initial results from serial dissolution experiments of southern ocean diatoms taken from culture. Fragilariopsis kerguelensis, Fragiliariopsis nana, Proboscia alata, and Psuedo-nitzschia subcurvata were completely dissolved in NaOH. Morphologic changes were monitored with SEM from samples taken at intervals during dissolution, and silica in solution was measured via absorbence spectroscopy. Percent silica lost is compared to changes in morphology in order to link the physical state of fossil diatoms to the amount of silica lost to solution, thus linking preservation and productivity.