Title: Tracking ecological mechanisms of the biological pump
Carbon fixed into organic matter by phytoplankton in the surface ocean can be sequestered into the deep ocean by sinking particles, a process known as the biological pump. The amount of carbon sequestered in the ocean by this process is poorly constrained, probably due to a lack of mechanistic observations that can be incorporated into models. To better quantify the mechanisms of the biological pump, we surveyed the identity and phytoplankton contents of sinking particles collected in sediment traps deployed in the mesopelagic for several days across ocean basins, and in sediment traps deployed at the abyssal seafloor of the California coast for 30 years (Station M). Particles were individual resolved through microscopy or in situ imaging followed by image processing. We then modeled the carbon exported by different particle types (e.g. aggregates, fecal pellets). To connect surface production with carbon export, the phytoplankton contents of bulk collected and individual isolated particles were resolved by DNA sequencing and microscopy. This talk will explore how the composition of sinking particles affect the magnitude and transfer efficiency of carbon flux and how specific phytoplankton groups are incorporated into different sinking particles. More observations that resolve export mechanisms at the particle scale will enable the generation of realistic models of the biological pump and improve quantification of the ocean's carbon cycle.