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Research Spending & Results

Award Detail

Awardee:UNIVERSITY OF SOUTHERN CALIFORNIA
Doing Business As Name:University of Southern California
PD/PI:
  • Douglas G Capone
  • (213) 740-2772
  • capone@usc.edu
Award Date:06/30/2014
Estimated Total Award Amount: $ 755,454
Funds Obligated to Date: $ 755,454
  • FY 2014=$755,454
Start Date:08/01/2014
End Date:07/31/2019
Transaction Type:Grant
Agency:NSF
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.050
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Collaborative Research: New Approaches to New Production
Federal Award ID Number:1437458
DUNS ID:072933393
Parent DUNS ID:072933393
Program:BIOLOGICAL OCEANOGRAPHY
Program Officer:
  • Michael Sieracki
  • (703) 292-7585
  • msierack@nsf.gov

Awardee Location

Street:University Park
City:Los Angeles
State:CA
ZIP:90089-0001
County:Los Angeles
Country:US
Awardee Cong. District:37

Primary Place of Performance

Organization Name:University of Southern California
Street:3616 Trousdale Parkway
City:Los Angeles
State:CA
ZIP:90089-0371
County:Los Angeles
Country:US
Cong. District:37

Abstract at Time of Award

Coastal marine ecosystems are seasonally dynamic and highly productive. Phytoplankton populations shift from nutrient replete conditions in the spring to nutrient poor conditions in other seasons. The San Pedro Ocean Time-series (SPOT), located 17 km offshore between Los Angeles Harbor and Catalina Island, is a representative and accessible model coastal system with regular sampling and a substantial archive of relevant observations. The SPOT program has cataloged the dynamics, diversity, and productivity of microbial populations since 2000. With rising carbon dioxide (CO2) concentrations and resulting decreases in surface pH, it is critically important to understand the nutrient controls on primary production in coastal waters and the capacity of coastal ecosystems to sequester CO2. This project will examine rates of primary production, nitrogen uptake associated with primary production, and the oxidation of ammonium to nitrate (nitrification), at SPOT over two seasonal cycles. It will also contribute to the development of human resources in the marine sciences through the training of undergraduate and graduate students at the University of Southern California and the University of Maryland. The researchers participate in education outreach activities (e.g. through the Centers for Ocean Sciences Education Excellence programs), and will incorporate findings from this study in those presentations. This project will investigate primary production and nitrogen (N) dynamics at SPOT and specifically implement an analysis of new production. The new production conceptual model has been a powerful organizing principle in biological oceanography and provides a means to constrain the amount of primary production that may be exported or "sequestered" from the system. Despite qualifications to the definitions of new and regenerated forms of N as originally articulated, the concept has, for the most part, been narrowly applied, specifying nitrate as the primary form of new N, and ammonium as the predominant recycled form. Evidence continues to accumulate that these definitions may warrant expansion. N fixation can be at times a substantial source of new N; similarly, forms of dissolved organic N (e.g., urea) may contribute significantly to recycled production, but the specific organisms taking part in these transformations are still uncertain. Nitrification in the upper water column may also compromise the strict definitions of new and recycled N. Scientists can now probe more deeply into new and regenerated production, and directly identify major agents of these processes using new molecular techniques. This project will quantify new and regenerated production in a coastal ecosystem, illuminating the predominant compounds involved. Rates of primary production, nitrate, ammonium and urea assimilation, N2 fixation, and nitrification will be determined in the upper water column in concert with monthly SPOT cruises. In tandem, two stable isotope probing (SIP) approaches (conventional SIP for nitrate, ammonium and urea uptake coupled to high throughput sequencing and microarray based Chip-SIP for N2 fixation) will be used to directly identify the major agents involved in these processes, along with the uptake of 13C-urea into nitrifier biomass. The following two hypotheses will be tested: 1. N2 fixation is a substantial source of new N in coastal waters of Southern California supporting export production. 2. Forms of dissolved organic N, and specifically urea, can be substrates for nitrification and contribute substantially to regenerated production.

Publications Produced as a Result of this Research

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Michael Morando and Douglas G. Capone "Direct utilization of organic N by phytoplankton and its role in N cycling within the Southern California Bight" Frontires in Microbiology: Aquatic Microbiology, v., 2018, p.. doi:doi.org/10.3389/fmicb.2018.02118 

Wilson, Samuel T Bange, Hermann W Arévalo-Martínez, Damian L Barnes, Jonathan Borges, Alberto Brown, Ian Bullister, John L Burgos, Macarena Capelle, David W Casso, Michael "An intercomparison of oceanic methane and nitrous oxide measurements" Biogeosciences, v.15, 2018, p.. doi:10.5194/bg-15-5891-2018 

Morando, M D.G. Capone "Intraclade heterogeneity in nitrogen utilization by marine prokaryotes revealed using stable isotope probing coupled with tag sequencing (Tag-SIP)" Frontiers in Aquatic Microbiology, v., 2016, p.. doi:doi: 10.3389/fmicb.2016.01932 

Laperriere, Sarah M Nidzieko, Nicholas J Fox, Rebecca J Fisher, Alexander W Santoro, Alyson E "Observations of Variable Ammonia Oxidation and Nitrous Oxide Flux in a Eutrophic Estuary" Estuaries and Coasts, v.42, 2019, p.. doi:10.1007/s12237-018-0441-4 

Morando, M and D.G. Capone "Intraclade heterogeneity in nitrogen utilization by marine prokaryotes revealed using stable isotope probing coupled with tag sequencing (Tag-SIP)." Frontiers in Aquatic Microbiology, v.7, 2016, p.. doi:10.3389/fmicb. 

Morando, M and D.G. Capone "Intraclade heterogeneity in nitrogen utilization by marine prokaryotes revealed using stable isotope probing coupled with tag sequencing (Tag-SIP)" Frontiers in Aquatic Microbiology, v.7, 2016, p.. doi:10.3389/fmicb.2016.01932 


Project Outcomes Report

Disclaimer

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 ocean is an important part of the earth's climate system. One aspect of this system is the biological pump—the growth, death, and eventual sinking of small algae (phytoplankton) from the surface to the deep ocean. One way of measuring the strength of the biological pump is by measuring the amount of nitrogen algae take up in the form of nitrate, and calculating how much growth, or carbon fixation, this nitrogen would support. This method is based on the hypothesis that nitrate is a "new" form of nitrogen to the surface ocean from the deep ocean, as opposed to nitrogen that is recycled internally within the upper ocean. Because what comes up must eventually go down, this "new production" paradigm is powerful because it allows an estimation of the amount of carbon sinking to the deep ocean by making a relatively simple measurement of nitrogen uptake.

Our project, a collaboration between laboratories at Univ. of Southern California and UC Santa Barbara, showed that, in fact, nitrate is not always a "new" form of nitrogen. Our research measured rates of nitrification—a microbial process that produces nitrate—in the upper ocean approximately every month for two years in the coastal ocean off southern California. We found that up to 20% of the nitrate taken up by phytoplankton was not "new" but produced by nitrification. We also measured rates of primary production and nitrification supported by the organic nitrogen source, urea, two processes whose importance was not previously well understood. We found that urea usage can account for a large fraction of both the nitrogen demand of phytoplankton as well as of the nitrate produced by nitrification, which could transform our understanding of nitrogen dynamics in the upper ocean. Surprisingly, diatoms, important primary producers in coastal waters, accounted for much of the urea uptake.

Microorganisms involved in nitrification are also critical to removing ammonia from aquarium and aquaculture operations. The results from this project help us to better understand their ecology and physiology.

A second outcome of this award is an improved understanding of the production and transport of nitrous oxide in the ocean. Nitrous oxide is a greenhouse gas that is produced by microbes; its production in enhanced at low oxygen concentrations. Monthly measurements of nitrous oxide concentrations showed that northward flowing currents transport nitrous oxide from low-oxygen regions of the ocean off the coast of Mexico to the Southern California Bight where it can be upwelled to the surface and enter the atmosphere. These results show that regions of nitrous oxide production can be very far from where nitrous oxide ultimately reaches the atmosphere, and that studies of this gas should not be restricted to low-oxygen regions.

This award trained three graduate students (one at UCSB and two at USC) and four technicians in analytical chemistry and oceanographic sampling and supported the research of an early career researcher. Several undergraduates were involved in the project in the two laboratories.


Last Modified: 01/10/2020
Modified by: Douglas G Capone

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