2017-2018 USAP Field Season
Chemoautotrophy in Antarctic bacterioplankton communities supported by the oxidation of urea-derived nitrogen
Dr. James Hollibaugh
University of Georgia
Supporting Stations: ARSV Laurence M. Gould
Chemoautotrophic production based on nitrification has been proposed to augment bacterioplankton, and thus microbial loop production in polar regions, particularly during winter when photoautotrophy is reduced by low irradiance and ice cover. Researchers will use 15N- and 14C-labeled substrates to quantify oxidation rates of 15N supplied as NH4+, urea, and NO2-, allowing estimation of the contribution of urea-derived nitrogen (N) and complete nitrification (NH4+ to NO3-) to chemoautotrophy and bacterioplankton production in Antarctic coastal waters. Other samples will be taken to measure the concentrations of NO3-, NO2-, NH4+, and urea for real-time Polymerase chain reaction (qPCR) analysis of the abundance of relevant microorganisms and for studies of related processes.
Field Season Overview
Researchers will sample continental shelf and slope waters while onboard the ARSV Laurence M. Gould (LMG) during the January 2018 LMG18-01 cruise. They will sample three water masses at approximately 15 stations: 0-50 m, 70-100 m, and >150 m, and will sample these stations on approximately five PAL-LTER grid lines with a focus on inshore, mid-shelf and offshore sites. They will also conduct experiments during inshore Palmer Long Term Ecological Research (PAL-LTER) process stations and at other locations, as opportunities arise. The standard conductivity temperature depth (CTD) rosette will sample approximately 4 L from each of the three depths per station and ~ 14 L from each depth at each process station. Multiple onboard incubations will be conducted using 15N- and 14C-labeled substrates. Onboard incubations will be conducted in the onboard Percival incubator (shared) and 14C radioisotope van (shared). Onboard analyses will include NH4+ and NO2.
Deploying Team Members