Dataset: Sediment trap-derived flux of salp fecal pellets (carbon mass flux) from the "SalpPOOP" cruise on R/V Tangaroa during October and November 2018

Data comes from VERTEX-style, surface-tethered, drifting sediment trap deployments. Particle interceptor tubes were deployed on cross-pieces with 16 tubes attached. Tubes were deployed with a dense formaldehyde brine created by adding NaCl and formaldehyde to filtered seawater. After recovery, overlying seawater was removed from each cruise by gentle suction. Tubes were then gravity filtered through a 200-micron nitex mesh filter, and the 200-micron filters were carefully analyzed under a stereomicroscope and all metazoan zooplankton "swimmers" were removed from the sample. Material remaining on the 200-micron filters (i.e., sinking material) was then imaged with a macrophotography rig and subsequently rinsed back into the original sample tube (i.e., re-combined with the <200-micron sinking material). Samples were then separated and filtered onto different types of filters for a suite of different analyses including: particulate organic carbon flux, particulate nitrogen flux, carbon and nitrogen isotopes, chlorophyll a and phaeopigment flux, microscopy, genetic analyses, and 234Th flux.

>200-um filters for each sediment trap tube (used for removing mesozooplankton swimmers) was imaged using a Canon 5D mark II camera with attached 100-mm F/2.8 macro lens mounted in a downward-facing macrophotography rig. Images were manually analyzed using Image J to determine morphometric measurements for each large salp fecal pellet, which were then used to estimate biovolume. Carbon content of each fecal pellet was determined from a log-log relationship between pellet volume and pellet carbon mass. This relationship was determined from individual fecal pellets that were collected at sea, imaged to determine biovolume, and analyzed for carbon and nitrogen content on an isotope ratio mass spectrometer. Please note that these pellet flux measurements should be considered a conservative estimate of total salp fecal pellet mass flux as they only include intact pellets that could be identified from the images take of the filters.