Zooplankton-mediated aggregate formation was measured during seven Bermuda Atlantic Time-series Study (BATS) cruises (AE2112, AE2114, AE2124, AE2204, AE2214, AE2224, AE2306) aboard the R/V Atlantic Explorer between 2021-07-08 and 2023-03-26 in the Sargasso Sea near Bermuda. This dataset reports roller-tank incubation data documenting the formation of zooplankton-mediated aggregates are also included, with records of individuals used and aggregate production outcomes. Together with the related datasets, these data provide integrated measurements linking zooplankton identity, size, fecal-pellet production, pellet elemental composition, and aggregate formation, supporting process-based analyses of zooplankton roles in particle production and vertical carbon transfer at BATS. The data were collected aboard the R/V Atlantic Explorer through the collaborative efforts of the laboratories of Dr. Susanne Neuer, Dr. Amy Maas, and Dr. Leocadio Blanco-Bercial, affiliated with Arizona State University and the Bermuda Institute of Ocean Sciences.

Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
• Data Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Zooplankton Collection

Live zooplankton were collected using a 1-m², 150-µm mesh Reeve net for roller tank incubation experiments. Unfiltered seawater used to fill the roller tanks was collected from the same depth as the zooplankton.

Roller Tank Incubations

Roller tank experiments were conducted using eight 5-L acid-washed roller tanks filled with unfiltered seawater collected from the same depth as the zooplankton. These incubations were used to assess the formation of zooplankton-mediated aggregates. Live zooplankton individuals were incubated in rotating tanks under controlled conditions, and aggregate production was recorded over a three-day incubation period. Dataset records include the taxonomic identity of incubated individuals and qualitative and quantitative descriptions of aggregate formation.

Raw zooplankton sample metadata (cruise ID, station, date, time, depth interval, and diel period) were recorded at sea during each cruise. Zooplankton taxa used in roller tank experiments were identified to the lowest practical taxonomic level using stereomicroscope images and standard taxonomic references.

Roller tank experiment data were processed by recording the presence, number, and size of aggregates formed during each incubation period and associating these observations with the taxonomic identity of the incubated zooplankton.

All data were compiled, quality-checked for transcription errors, and formatted into standardized tables for submission. No statistical analyses, model-based flux calculations, or graphical processing are included in the submitted datasets.

**Version 1**

- Loaded "Roller_Tanks.csv" as resource "roller_tanks" (CSV format, header row 1, treating "" and "nd" as missing values)
- Converted Start_Date from format "%m/%d/%Y" to date output "%Y-%m-%d"
- Converted Takedown_Date from format "%m/%d/%Y" to date output "%Y-%m-%d"
- Combined Start_Date and Start_Time fields (Atlantic/Bermuda timezone) into new datetime field Datetime_Start_UTC, converting to UTC, formatted as "%Y-%m-%dT%H:%MZ"
- Renamed fields: Min_Depth_(m) to Min_Depth, Max_Depth_(m) to Max_Depth, #_of_Zooplankton_At_Beginning to Num_Zooplankton_At_Beginning, #_Zooplankton_Alive to Num_Zooplankton_Alive, #_Fecal_Aggregate to Num_Fecal_Aggregate, #_Fecal_Pellet to Num_Fecal_Pellet, Animal/FecalPellet_Notes to Animal_FecalPellet_Notes
- Edited two cells: row 9 Takedown_Date set to 2021-08-13 and Takedown_Time set to 19:00; row 45 Takedown_Date set to 2022-12-04 and Takedown_Time set to 3:00, upon submitter request
- Renamed resource from "roller_tanks" to "998220_v1_roller_tank_exp"
- Output written to 998220_v1_roller_tank_exp.csv

**Version 2**

Addition of missing time values provided by submitter. Processing was done using original submitted file with missing data added to edited cells. See details below.

- Loaded "Roller_Tanks.csv" as resource "roller_tanks" (CSV format, header row 1, treating "" and "nd" as missing values)
- Edited cells in rows 21, 22, 38, and 40 to fill missing End_Time, Total_Time, Hours, and Start_Time values provided by submitter
- Converted Start_Date from format "%m/%d/%Y" to date output "%Y-%m-%d"
- Converted Takedown_Date from format "%m/%d/%Y" to date output "%Y-%m-%d"
- Combined Start_Date and Start_Time fields (Atlantic/Bermuda timezone) into new datetime field Datetime_Start_UTC, converting to UTC, formatted as "%Y-%m-%dT%H:%MZ"
- Renamed fields: Min_Depth_(m) to Min_Depth, Max_Depth_(m) to Max_Depth, #_of_Zooplankton_At_Beginning to Num_Zooplankton_At_Beginning, #_Zooplankton_Alive to Num_Zooplankton_Alive, #_Fecal_Aggregate to Num_Fecal_Aggregate, #_Fecal_Pellet to Num_Fecal_Pellet, Animal/FecalPellet_Notes to Animal_FecalPellet_Notes
- Edited two cells: row 9 Takedown_Date set to 2021-08-13 and Takedown_Time set to 19:00; row 45 Takedown_Date set to 2022-12-04 and Takedown_Time set to 3:00, upon submitter request
- Output written to 998220_v2_roller_tank_exp.csv

Coverage: Sargasso Sea/BATS area

NSF Award Abstract:
The purpose of this collaborative project is to advance understanding of the role of marine planktonic animals (or zooplankton) in the biological pump, or transport of carbon from surface to deeper ocean waters. This movement of carbon from surface to deep ocean water can ultimately affect carbon dioxide in the atmosphere, with implications for global climate. Many marine zooplankton, including species of copepods and krill, play a direct role in the biological pump both because they are abundant and because they can migrate from surface waters at night, where they feed, to depths of more than 500 m at night. At the same time, some organisms called flux feeders will remain at depth and do not migrate. Instead, they rely on particles produced by other zooplankton feeding in surface waters. In this project, the investigators are focusing on populations of flux feeders in the deeper ocean waters of the Sargasso Sea. They are leveraging an ongoing long-term research program, conducting field collections using specialized nets and particle traps, as well lab experiments, as a way to understand how these organisms modify the particles around them. This project is supporting a postdoctoral scientist and providing research experiences for undergraduates at two institutions. An education specialist is creating lesson plans for an award-winning Ask-A-Biologist website, designed for public and K-12 audiences. Images of zooplankton will be disseminated to the public and scientific community via EcoTaxa (a web platform devoted to plankton biodiversity, with images and taxonomic annotation) and physical samples will be archived as part of a teaching library.

The oceanic biological carbon pump refers to the export of dissolved and particulate organic carbon to the deep ocean, and it is a significant driver of atmospheric carbon uptake by the oceans. Evidence from long-term research carried out at the Bermuda Atlantic Time-series Study (BATS) site suggests that the spectrum of particles collected by gel-traps below the euphotic zone changes drastically below 150 m, which is attributed to resident populations of zooplankton that feed on vertically migrating zooplankton as well as sinking particles. The goals of this study are to investigate the role of different zooplankton taxa on both particle aggregate formation and in particle transformation, and to compare and characterize the particles generated by the zooplankton communities with those collected by particle traps. The investigators are combining field collections with experiments onboard ship and in environmental chambers. They are collecting samples over two years, with three cruises a year to capture distinct seasons. They are assessing high-resolution vertical distribution of zooplankton in the upper 600 m using Multiple Opening-Closing Net and Environmental Sensing System (MOCNESS) tows during day- and night-time, to distinguish diel vertical migrators from resident populations and to quantify contributions to particulate organic carbon flux via fecal pellet production. On each cruise, sinking particles are being collected using gel trap tubes attached to the particle traps deployed monthly at BATS. In addition, roller tank experiments are determining how individual zooplankton mediate aggregate formation. Particle types and fecal pellets are being characterized using image analysis and DNA-based analysis of microbial communities. Finally, ongoing data collection from the long-term BATS program is providing invaluable environmental context and will ensure results from this study contribute to ongoing community efforts to observe and predict the fate of carbon in our global system.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.