The Roughage Effect of Mineral Material on Marine Grazers: Potential Implications for the Global Carbon Cycle Gillian Meg Stewart, School of Earth and Environmental Sciences, Queens College, CUNY, Flushing, NY 11367 CONTROL EXP: ADD DUST Plant cell Copepod fecal pellets Mineral particles such as dust can be a source of limiting micronutrients in marine ecosystems, and also a source of ballast material that can facilitate the sinking of carbon. We have conducted culture experiments which suggest that suspended mineral particles in feeding solutions can reduce the carbon assimilation of grazers by 5-36%, thus enhancing the carbon content of fecal particles that sink to the seafloor, and potentially increasing the carbon flux from the surface ocean via the biological pump. Running the results through a carbon model reveals that we can lower atmospheric carbon by as much as 5%.This study suggests a link between the concentrations of suspended particulate matter and ocean carbon sequestration and provides a mechanistic explanation for how mineral ballasting is an effective means of transferring carbon to the deep ocean. Experimental Design When C assimilation is reduced in the model to the left (g), the efficiency of the biological pump increases, decreasing atm. CO2 in the simulation to the right Years From Now 290 294 298 302 306 400 800 1200 1600 2000 2400 UVic Marine Ecosystem Model, with a term for C assimilation Decreased in atmospheric CO2 according to GCM when dust is added to the surface ocean in realistic amounts.