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
• Program Information
• Funding

Rates of microzooplankton grazing were determined from serial dilution experiments as described in Landry et al. (2002). Seawater for most experiments was collected in 30-liter Go-Flo bottles, except for a few stations sampled with CTD Niskin bottles. Generally, two experiments were run at each station – one with water collected from the depth of penetration of ~25% of surface PAR, the other varying from 10 to 58% PAR depending on relative mixed-layer versus euphotic zone depths.

For each experiment, ten 2-liter polycarbonate bottles were used to establish a nutrient-enriched dilution series consisting of replicated bottles with 22, 45, 65, 86, and 100% natural (unfiltered) seawater with final concentrations of 0.5 micromolar (µM) ammonium, 0.03 µM phosphate, 1.0 nM FeSO4, and 0.1 nM MnSO4. Five additional bottles were filled with whole seawater with no nutrient enrichment. Two were used for initial samples, and the final three were incubated as natural seawater controls. All bottles were tightly capped after filling and incubated for ~48 hours in seawater-cooled incubators calibrated to the relative PAR light levels.

Initial and final concentrations of bacterial cells were determined from 1-milliliter (mL) samples preserved with 0.5% paraformaldehyde, frozen in liquid nitrogen, and analyzed with a Coulter EPICS 753 flow cytometer with two lasers (UV and 488 nanometers (nm)) after Hoechst 33342 staining. Net rates of change (ki, d-1) during the incubations were computed from initial and final cell counts in each bottle; k = ln(Pf/Pi)/t, where t = 2 days. Mortality rates due to microzooplankton grazing (m, d-1) were computed as the slopes of the linear regressions between kiand Di for the nutrient-amended bottles, and growth rates (µ, d-1) were determined from net growth in bottles without added nutrients (Landry and Hassett, 1982).

- Imported file "AESOPS_bacterivory_BCO_DMO submission 5Nov2024.csv" into the BCO-DMO system.
- Converted Date column to YYYY-MM-DD format.
- Renamed fields to comply with BCO-DMO naming conventions.
- Saved final file as "943333_v1_bacterivory_aesops.csv".

The U.S. Southern Ocean JGOFS program, called Antarctic Environment and Southern Ocean Process Study (AESOPS), began in August 1996 and continued through March 1998. The U.S. JGOFS AESOPS program focused on two regions in the Southern Ocean: an east/west section of the Ross-Sea continental shelf along 76.5°S, and a second north/south section of the Southern Ocean spanning the Antarctic Circumpolar Current (ACC) at ~170°W (identified as the Polar Front). The science program, coordinated by Antarctic Support Associates (ASA), comprised eleven cruises using the R.V.I.B Nathaniel B. Palmer and R/V Roger Revelle as observational platforms and for deployment and recovery of instrumented moorings and sediment-trap arrays. The Ross-Sea region was occupied on six occasions and the Polar Front five times. Mapping data were obtained from SeaSoar, ADCP, and bathymetric systems. Satellite coverage was provided by the NASA SeaWiFS and the NOAA/NASA Pathfinder programs.

The United States Joint Global Ocean Flux Study was a national component of international JGOFS and an integral part of global climate change research.

The U.S. launched the Joint Global Ocean Flux Study (JGOFS) in the late 1980s to study the ocean carbon cycle. An ambitious goal was set to understand the controls on the concentrations and fluxes of carbon and associated nutrients in the ocean. A new field of ocean biogeochemistry emerged with an emphasis on quality measurements of carbon system parameters and interdisciplinary field studies of the biological, chemical and physical process which control the ocean carbon cycle. As we studied ocean biogeochemistry, we learned that our simple views of carbon uptake and transport were severely limited, and a new "wave" of ocean science was born. U.S. JGOFS has been supported primarily by the U.S. National Science Foundation in collaboration with the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration, the Department of Energy and the Office of Naval Research. U.S. JGOFS, ended in 2005 with the conclusion of the Synthesis and Modeling Project (SMP).