USAP-DC

This project seeks to make detailed measurements of the oxygen content of the surface ocean along the Western Antarctic Peninsula. Detailed maps of changes in net oxygen content will be combined with measurements of the surface water chemistry and phytoplankton distributions. The project will determine the extent to which on-shore or offshore phytoplankton blooms along the peninsula are likely to lead to different amounts of carbon being exported to the deeper ocean. The project will analyze oxygen in relation to argon that will allow determination of the physical and biological contributions to surface ocean oxygen dynamics. These assessments will be combined with spatial and temporal distributions of nutrients (iron and macronutrients) and irradiances. This will allow the investigators to unravel the complex interplay between ice dynamics, iron and physical mixing dynamics as they relate to Net Community Production (NCP) in the region. NCP measurements will be normalized to Particulate Organic Carbon (POC) and be used to help identify area of "High Biomass and Low NCP" and those with "Low Biomass and High NCP" as a function of microbial plankton community composition. The team will use machine learning methods- including decision tree assemblages and genetic programming- to identify plankton groups key to facilitating biological carbon fluxes. Decomposing the oxygen signal along the West Antarctic Peninsula will also help elucidate biotic and abiotic drivers of the O2 saturation to further contextualize the growing inventory of oxygen measurements (e.g. by Argo floats) throughout the global oceans.

Person	Role
Cassar, Nicolas	Investigator and contact
Lin, Yajuan	Researcher
Hagge, Perrin	Researcher
de Souza, Ariana	Researcher
Gu, Shuai	Researcher

Antarctic Organisms and Ecosystems

Award # 1643534

USAP-1643534_1

Deployment	Type
Deployment of Equilibrator Inlet Mass Spectrometer and molecular sampling on Palmer LTER grid	ship expedition

None in the Database

Repository	Title (link)	Format(s)	Status
NCBI	Palmer LTER 18S rRNA gene metabarcodin	Not Provided	exists
NCBI	rDNA amplicon sequencing of WAP microbial community	Not Provided	exist

1. Lin Y. et al. (2017) Specific eukaryotic plankton are good predictors of net community production in the Western Antarctic Peninsula. Scientific Reports. 7: 14845. (doi:10.1038/s41598-017-14109-1)
2. Moreno, C.M. et al. 2018. Examination of gene repertoires and physiological responses to iron and light limitation in Southern Ocean diatoms. Polar Biology. (doi:10.1007/s00300-017-2228-7 )
3. Brown, M. S., Bowman, J. S., Lin, Y., Feehan, C. J., Moreno, C. M., Cassar, N., … Schofield, O. M. (2021). Low diversity of a key phytoplankton group along the West Antarctic Peninsula. Limnology and Oceanography. (doi:10.1002/lno.11765)
4. Ducklow, H. W., Stukel, M. R., Eveleth, R., Doney, S. C., Jickells, T., Schofield, O., … Cassar, N. (2018). Spring–summer net community production, new production, particle export and related water column biogeochemical processes in the marginal sea ice zone of the Western Antarctic Peninsula 2012–2014. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 376(2122), 20170177. (doi:10.1098/rsta.2017.0177)
5. Lin, Y., Moreno, C., Marchetti, A., Ducklow, H., Schofield, O., Delage, E., … Cassar, N. (2021). Decline in plankton diversity and carbon flux with reduced sea ice extent along the Western Antarctic Peninsula. Nature Communications, 12(1). (doi:10.1038/s41467-021-25235-w)
6. Lin, Y., Gifford, S., Ducklow, H., Schofield, O., & Cassar, N. (2019). Towards Quantitative Microbiome Community Profiling Using Internal Standards. Applied and Environmental Microbiology, 85(5). (doi:10.1128/aem.02634-18)
7. Li, Z., Lozier, M. S., Cassar, N. 2021. Southern Ocean mixed layer dynamics and net community production on intra-seasonal, seasonal, interannual, and multi-year timescales. Journal of Geophysical Research – Oceans (doi:10.1029/2021JC017537)