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Award Detail

Doing Business As Name:Old Dominion University Research Foundation
  • Alexander B Bochdansky
  • (757) 683-4933
Award Date:07/03/2012
Estimated Total Award Amount: $ 299,367
Funds Obligated to Date: $ 299,367
  • FY 2012=$299,367
Start Date:07/15/2012
End Date:06/30/2016
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.078
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Collaborative research: TRacing the fate of Algal Carbon Export in the Ross Sea (TRACERS)
Federal Award ID Number:1142097
DUNS ID:077945947
Program:ANT Ocean & Atmos Sciences

Awardee Location

Street:4111 Monarch Way
Awardee Cong. District:03

Primary Place of Performance

Organization Name:Old Dominion University
Street:5115 Hampton Blvd.
Cong. District:02

Abstract at Time of Award

Intellectual Merit: Sinking particles are a major element of the biological pump and they are commonly assigned to two fates: mineralization in the water column and accumulation at the seafloor. However, there is another fate of export hidden within the vertical decline of carbon, the transformation of sinking organic matter to fine suspended and/or dissolved organic fractions. This process has been suggested but has rarely been observed or quantified. As a result, it is presumed that the solubilized fraction is largely mineralized over short time scales. However, global ocean surveys of dissolved organic carbon are demonstrating a significant water column accumulation of organic matter under high productivity environments. This proposal will investigate the transformation of organic particles from sinking to solubilized phases of the export flux in the Ross Sea. The Ross Sea experiences high export particle production, low dissolved organic carbon export with overturning circulation, and the area has a predictable succession of production and export events. In addition, the basin is shallow (< 000 m) so the products the PIs will target are relatively concentrated. To address the proposed hypothesis, the PIs will use both well-established and novel biochemical and optical measures of export production and its fate. The outcomes of this work will help researchers close the carbon budget in the Ross Sea. Broader impacts: This research will support graduate and undergraduate students and will provide undergraduates and pre-college students with field-based research experience. Scientifically, this research will increase understanding of carbon sinks in the Ross Sea and will help develop new tools for identifying, quantifying, and tracking that carbon. The PIs will interface with K-12 students through daily reports from the field and through educational modules developed by several of the PIs in collaboration with science education specialists and college students. A K-12 educator will be included on the research cruises. Outreach will be through COSEE Florida and the Maritime Center in Norfolk, VA.

Publications Produced as a Result of this Research

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Alexander B. Bochdansky, Melissa A. Clouse, Dennis A. Hansell "Mesoscale and high-frequency variability of macroscopic particles (> 100 micrometer) in the Ross Sea and its relevance for late-season particulate carbon export" Journal of Marine Systems (Ross Sea Special Issue), v.166, 2017, p.120. doi:10.1016/j.jmarsys.2016.08.010 

Project Outcomes Report


This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

The Ross Sea plays a major role in the transfer of organic carbon from the surface into the deep sea due to the combination of high seasonal productivity and Antarctic bottom water formation. This part of the collaborative project examined the abundances and relative distribution of macroscopic particles (larger than 100 micrometers) in the Ross Sea late in the season February - March when the Ross begins to freeze over.The measurements were based on a combined deployment of a video particle profiler (VPP) and a high-resolution digital holographic microscope (DIHM) custom-built for deep-sea deployments. Long-distance (100s of kilometers) and short-distance (10s of kilometers) sections showed high variability of particle distributions that co-varied with the density structure of the water column. Particle export was apparent at sites of locally weakened pycnoclines, likely an indirect effect of nutrient mixing into the surface layer and local blooms that lead to export. Particle volume abundances at 200-300 m depth were highly correlated with particle volume abundances in the upper mixed layer (<60 m), consistent with particles at depth primarily the result of export rather than lateral advection. A dominant group of phytoplankton is the haptophyte Phaeocystis antarctica which forms globular colonies. With the digital inline holographic camera we were able to determine the vertical distribution of these colonies at very high resolution (i.e., in meter bins). At the beginning of our expedition, Phaeocystis antarctica were retained in the upper mixed layer but sank below the euphotic zone within a period of two weeks. Fine-scale analysis at a resolution smaller than1 m revealed a highly patchy environment in all casts and the degree of this patchiness depended on the depth layer and the location in the Ross Sea. Patchiness, as determined by the Lloyd index of patchiness and the Index of Aggregation, increased in and below the pycnocline presumably due to aggregation of particles while accumulating on density gradients. In contrast, particles in the upper mixed layer and in the nepheloid layers (i.e., the layers of high particle abundance close to the ocean floor) were more randomly distributed. In 40 of the 84 VPP depth profiles, a periodicity of particle peaks ranged from 10 to 90 m with a mode of 30 m, which can be regarded as the “relevant scale” or “characteristic patch size” of the vertical distribution of particles. While chlorophyll fluorescence and particle mass determined by VPP were significantly correlated at higher particle abundances, the relationship changed from cast to cast, reflecting changes in the relative contribution of fresh phytoplankton to total particle mass. Particles that sank below the main pycnocline were composed of phytoplankton, marine snow with and without embedded phytoplankton, crustacean plankton, and a surprisingly high percentage of heterotrophic (and perhaps mixotrophic) protists, such as acantharians and tintinnids.

This project contributed significantly to undergraduate and graduate student education at Old Dominion University. Outreach efforts included collaboration with the Virginia Aquarium, tours of our facilities to the general public, and demonstrations and workshops for middle-school students and their mentors. In these sessions, students were able to lay their hands on oceanographic equipment, and performed their own reconstruction of organisms from holographic images originally collected in the seas surrounding Antarctica.



Last Modified: 01/19/2017
Modified by: Alexander B Bochdansky

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