Abstract. Marine particles of different nature are found throughout the global ocean. The term “marine particles” describes detritus aggregates and fecal pellets as well as bacterioplankton, phytoplankton, zooplankton and nekton. Here, we present a global particle size distribution dataset obtained with several Underwater Vision Profiler 5 (UVP5) camera systems. Overall, within the 64 µm to about 50 mm size range covered by the UVP5, detrital particles are the most abundant component of all marine particles; thus, measurements of the particle size distribution with the UVP5 can yield important information on detrital particle dynamics. During deployment, which is possible down to 6000 m depth, the UVP5 images a volume of about 1 L at a frequency of 6 to 20 Hz. Each image is segmented in real time, and size measurements of particles are automatically stored. All UVP5 units used to generate the dataset presented here were inter-calibrated using a UVP5 high-definition unit as reference. Our consistent particle size distribution dataset contains 8805 vertical profiles collected between 19 June 2008 and 23 November 2020. All major ocean basins, as well as the Mediterranean Sea and the Baltic Sea, were sampled. A total of 19 % of all profiles had a maximum sampling depth shallower than 200 dbar, 38 % sampled at least the upper 1000 dbar depth range and 11 % went down to at least 3000 dbar depth. First analysis of the particle size distribution dataset shows that particle abundance is found to be high at high latitudes and in coastal areas where surface productivity or continental inputs are elevated. The lowest values are found in the deep ocean and in the oceanic gyres. Our dataset should be valuable for more in-depth studies that focus on the analysis of regional, temporal and global patterns of particle size distribution and flux as well as for the development and adjustment of regional and global biogeochemical models. The marine particle size distribution dataset (Kiko et al., 2021) is available at https://doi.org/10.1594/PANGAEA.924375.

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Models and observations suggest that particle flux attenuation is lower across the mesopelagic zone of anoxic environments compared to oxic environments. Flux attenuation is controlled by microbial metabolism as well as aggregation and disaggregation by zooplankton, all of which shape the relative abundance of differently sized particles. Observing and modeling particle spectra can provide information about the contributions of these processes. We measured particle size spectrum profiles at one station in the oligotrophic Eastern Tropical North Pacific Oxygen Deficient Zone (ETNP ODZ) using an underwater vision profiler (UVP), a high‐resolution camera that counts and sizes particles. Measurements were taken at different times of day, over the course of a week. Comparing these data to particle flux measurements from sediment traps collected over the same time‐period allowed us to constrain the particle size to flux relationship, and to generate highly resolved depth and time estimates of particle flux rates. We found that particle flux attenuated very little throughout the anoxic water column, and at some time points appeared to increase. Comparing our observations to model predictions suggested that particles of all sizes remineralize more slowly in the ODZ than in oxic waters, and that large particles disaggregate into smaller particles, primarily between the base of the photic zone and 500 m. Acoustic measurements of multiple size classes of organisms suggested that many organisms migrated, during the day, to the region with high particle disaggregation. Our data suggest that diel‐migrating organisms both actively transport biomass and disaggregate particles in the ODZ core.

Experiential learning in the field is an opportunity for students to enter the heart of a scientific discipline. Through such experience, they can extract conceptual clues and discover motivational stepping stones that will potentially influence the rest of their education and career choice. Unfortunately, in Biology, the inescapable topic of Next-Generation Sequencing represents a challenge when it comes to create an educational curriculum that aims to provide students with hands-on experience on sequencers. It is an even more difficult task to accomplish if one’s purpose was to set such curriculum in a field situation. However, in recent years, educators have seen possibility to bring Next-Generation Sequencing to the reach of students more easily, with the Oxford Nanopore MinION, a low-budget, user-friendly, hand-held sequencer. Academic researchers have illustrated the performances of this device in the field and are inspirational for curricula aiming to take the next generation of scientists in the outdoors. We designed a modular 5-day workshop, with nanopore sequencing to be performed in field conditions. Here we describe the material and methods that lead the students and instructors from sample collection, DNA extraction and preparation for nanopore sequencing with MinION to real-time analysis of the data collected. This curriculum was implemented for the first-time aboard Research Vessel Sikuliaq during a transit organized by the STEMSEAS program at Columbia University in collaboration with the University of Alaska BLaST program. The line of investigation formulated for the workshop was an open-ended question that led the students to establish a proof of concept in terms of technology deployment at sea: what will show metagenomic results from DNA obtained from sea water and sequenced with Oxford Nanopore MinION? The workshop took place in October 2018 while Research Vessel Sikuliaq sailed the Alaskans seas for 7 days. Students successfully used nanopore sequencing for multiple metagenomic seawater samples. Their introductory analysis was consistent with environmental conditions and they were able to present their results by the end of the workshop.

Abstract. Marine particles of different nature are found throughout the global Ocean. The term "marine particles" describes detritus aggregates, fecal pellets, but also bacterio-, phyto-, zooplankton and nekton. Here we present a global particle size distribution dataset obtained with several Underwater Vision Profiler 5 (UVP5) camera systems. Overall, within the 64 μm to about 50 mm size range covered by the UVP5, detrital particles are the most abundant component of all marine particles in this size range and thus measurements of the particle size distribution with the UVP5 can yield important information on detrital particle dynamics. During deployment, which is possible down to 6000 m depth, the UVP5 images a volume of about 1 L at a frequency of 6 to 20 Hz. Each image is segmented in real time and size measurements of particles are automatically stored. All UVP5 units used to generate the here presented dataset were inter-calibrated using a UVP5 High Definition unit as reference. Our consistent particle size distribution dataset contains 8805 vertical profiles collected between 2008-06-19 and 2020-11-23. All major ocean basins, as well as the Mediterranean and the Baltic Sea were sampled. 19 % of all profiles had a maximum sampling depth shallower than 200 dbar, 80 % had a maximum sampling depth greater than 200 dbar, 38 % sampled at least the upper 1000 dbar depth range and 11 % went down to at least 3000 dbar depth. First analysis of the particle size distribution dataset shows that particle abundance is found to be high at high latitudes and in coastal areas where surface productivity or continental inputs are elevated. Lowest values are found in the deeep ocean and in the oceanic gyres. Our dataset should be valuable for more in-depth studies that focus on the analysis of regional, temporal and global patterns of particle size distribution and flux as well as for the development and adjustment of regional and global biogeochemical models. The marineparticle size distribution dataset (Kiko et al., 2021) is available at https://doi.pangaea.de/10.1594/PANGAEA.924375.