Table of Contents

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

Zooplankton Collection

Live zooplankton were collected during the March 2023 cruise (AE2306) using a 1-m², 150-µm mesh Reeve net for fecal pellet elemental analysis experiments.

Fecal Pellet Incubation and Collection

Target zooplankton taxa were incubated individually in 1-L acid-washed plastic containers ("Copepotties") filled with 0.2-µm filtered seawater. Each container included an inner insert constructed from a 1-mm mesh-bottomed plastic cup to allow separation of fecal pellets from the zooplankton. Incubations were conducted in the dark at approximately 20°C for 8–12 hours. Following incubation, fecal pellets were collected under a dissection microscope using glass pipettes and rinsed three times with nuclease-free water. Pellets were imaged at 63× magnification under a stereomicroscope, and morphometric measurements were obtained using INFINITY ANALYZE 7 software (Teledyne Technologies, Inc).

Fecal Pellet Elemental Analysis

Individual fecal pellets were placed onto pre-combusted, pre-weighed GF/F filters (0.7-µm pore size). Filters were dried, and changes in mass were used to estimate pellet dry weight. Filters containing fecal pellets were acidified by exposure to concentrated HCl fumes for 16 hours to remove inorganic carbon and then dried prior to analysis. Carbon, hydrogen, and nitrogen content was quantified using a Costech ECS 4010 elemental combustion system. Pellet carbon density and C:N ratios were calculated using measured pellet dimensions and elemental data.

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 fecal pellet elemental analysis experiments were identified to the lowest practical taxonomic level using stereomicroscope images and standard taxonomic references.

Fecal pellet morphometric measurements (length, width, and projected area) were obtained from stereomicroscope images using INFINITY ANALYZE 7 software (Teledyne Technologies, Inc). Pellet volumes were calculated from measured dimensions assuming cylindrical geometry. Individual fecal pellet production rates were calculated by dividing the total number of pellets produced per individual by the incubation duration (hours).

Dry weight values for zooplankton individuals used in elemental analyses were determined from measured mass after drying.

For elemental analysis, GF/F filter tare weights were subtracted from post-sample weights to obtain fecal pellet dry mass. Carbon, hydrogen, and nitrogen values output by the elemental analyzer were blank-corrected using pre-combusted filter blanks. Carbon density and C:N ratios were calculated from measured elemental content and pellet volume.

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.

- Loaded CSV file CHN_Results.csv using filename as resource name (chn_results), with empty string and "nd" treated as missing values
- Renamed 12 fields to remove special characters and units from field names to comply with BCO-DMO naming guidelines: Max_Depth_(m) to Max_Depth, Min_Depth_(m) to Min_Depth, GFF_filter# to GFF_filter_num, #_Zooplankton to num_Zooplankton, #Fecal_pellet to num_Fecal_pellet, C/N to C_N, Blank_Corrected_mg_C_(from_CHN) to Blank_Corrected_mg_C_from_CHN, Total_Volume_(um^3) to Total_Volume, FPP_using_CHN_Exp_(mg_C_ind-1_hr-1) to FPP_using_CHN_Exp_rate, FPP_using_CHN_Exp_(mg_C_ind-1) to FPP_using_CHN_Exp, Average_Animal_Dry_Weight_(mg) to Average_Animal_Dry_Weight, and StDev_Average_Animal_Dry_Weight_(mg) to StDev_Average_Animal_Dry_Weight
- Converted Date field from M/D/YYYY format to ISO 8601 date format (YYYY-MM-DD)
- Combined Date and Start_Time fields into new Datetime_Start field in ISO 8601 datetime format (YYYY-MM-DDTHH:MM), converting from Atlantic/Bermuda timezone to UTC; rows with missing Start_Time receive null Datetime_Start
- Renamed Datetime_Start -> Datetime_Start_UTC to reflect UTC timezone conversion
- Applied find and replace on Trawl column, removing the string "Tow" from values
- Output written to 998152_v1_chn_results.csv

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.