Award: OCE-1703422

This study tested whether different types of microscopic algae, animals, and their waste products sink out of the surface ocean and into deeper waters in different amounts, and with differing efficiencies. These sinking particles are part of the natural transfer of carbon out of the surface ocean and into deeper water, sometimes called ?the biological pump?. The sinking particles are important because they contain carbon that can be sequestered from the atmosphere for a long time in deep water, or used as food by microbes and animals living in deep water. We used new genetic sequencing methods to determine what kinds of microscopic algae and animals (aka ?plankton?) sank out of the surface ocean and to infer reasons for why they sank. We studied the sinking particles at three, contrasting open ocean locations between Hawaii and coastal California, in February 2017. We measured plankton and their waste in the ocean in several ways: 1) by chemical analysis of samples collected with sediment traps, which catch sinking particles in the ocean, 2) by putting sensors on a WireWalker, which is a wave-powered device that rapidly travels up and down on a wire hanging beneath a drifting buoy, 3) using an underwater holographic camera, 4) by genetic sequencing, and 5) by microscopic imaging of particles collected in the sediment traps. By using a variety of methods, we comprehensively characterized the upper water column, the types of particles that sank out, and the variability of sinking particles in different locations. Intellectual Merit: In order to measure and predict the amount of carbon sinking from the surface ocean into deep water, we must understand the relationships between the different types of plankton in the surface ocean, and the processes that cause them to sink in certain settings. The current understanding of the biological pump is based on studies that measure overall amounts and chemical compositions of sinking particles, but not the specific details of how organisms contribute to the sinking particle flux. This study aimed to combine new, detailed observational methods to measure particle size, shape, and biological origin, with other more traditional methods. Broader Impacts: This project involved multidisciplinary collaboration, supported 3 early-career female scientists, and provided several undergraduate and graduate student training opportunities. An undergraduate course was taught on board a research ship using telepresence to connect to students in the Inner Space Center at the University of Rhode Island, and results were presented to the public in a ?Science on Tap? talk in Saratoga Springs, NY. This work has also been communicated to the non-scientific public through blogs, videos, and the public communication channels of our participating institutions. The scientific outcomes are being presented at conferences and will be published in scientific journals. Last Modified: 03/29/2019 Submitted by: Margaret Estapa