This study investigated the link between surface phytoplankton communities and carbon export to the deep ocean using 18S rRNA gene sequencing of individual sinking particles collected in sediment traps. The relative abundance of exported phytoplankton taxa varied across functional groups and ecosystems. Approximately half of the sequences in sinking particles were found in large (>300 µm) particles and primarily belonged to taxa with small cell sizes (<50 µm). Taxa detected only in bulk trap samples (smaller size fraction) typically had large cell sizes (>500 µm). Particle degradation affected detectable rRNA gene communities differently across taxa. The study proposes a new approach incorporating genetic diversity into models of the ocean's biological carbon pump for better quantification of the ocean's carbon cycle.

Colleen A. Durkin, Ivona Cetinić, Margaret Estapa, Zrinka Ljubešić, Maja Mucko, Aimee Neeley, Melissa Omand