| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | December 22, 2014 |
| Latest Amendment Date: | December 22, 2014 |
| Award Number: | 1505604 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Henrietta Edmonds
hedmonds@nsf.gov (703)292-7427 OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | August 15, 2014 |
| End Date: | October 31, 2016 (Estimated) |
| Total Intended Award Amount: | $394,395.00 |
| Total Awarded Amount to Date: | $394,395.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1375 GREATE RD GLOUCESTER POINT VA US 23062-2026 (804)684-7000 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1375 Greate Road Gloucester Point VA US 23062-1346 |
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Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| NSF Program(s): | Chemical Oceanography |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
The US and other countries throughout the world are affected by harmful algal blooms (HABs) that negatively impact human health, marine ecosystems, fisheries resources, and local economies. Anthropogenic nutrient loadings have been linked to expanding HAB incidence, but the relationship is site- and organism-specific, and is still poorly understood. The main challenge in this regard is to determine the relative importance of natural versus anthropogenic nutrient sources in the development of an individual HAB species. Given the diverse nature of the planktonic assemblage in which HABs occur, and the lack of appropriate measurement techniques, this is exceedingly difficult to accomplish.
In this project, research teams at the Woods Hole Oceanographic Institution and University of Texas at Austin will take a novel approach to this challenge: They use use the nitrogen isotopic signature (del15N) of a species-specific HAB toxin to identify the nitrogen source and chemical form that promotes cell growth and toxin production. The bloom-forming dinoflagellate Alexandrium fundyense and its class of bioactive compounds, saxitoxins (STXs), are an ideal model system as STXs are nitrogen-rich and are typically only produced by a single species in mixed plankton assemblages. The guiding overall hypothesis is that the isotopic signature of a HAB-specific toxin can be used to discriminate between anthropogenic and natural sources of N and provide more details than bulk material del15N on the source, chemical form, and processing of N that lead to blooms of a particular toxic species. This hypothesis is based on the principle that human and animal waste in groundwater and sewage become 15N-enriched and inorganic fertilizers 15N-depleted, relative to natural sources of N in catchment waters. While the use of the isotopic ratio del15N of bulk biomass to identify nitrogen sources to coastal waters is a widely accepted practice, this use of a toxin as a species-specific tracer or marker is new and will provide details on the explicit source, chemical form, and processing of nitrogen that results in blooms of a particular HAB species.
Broader Impacts: This project addresses fundamental issues underlying the most widespread of all HAB poisoning syndromes, paralytic shellfish poisoning (PSP), a major form of shellfish poisoning that affects countries throughout the world. Project results can also assist in policy decisions about pollution control and other bloom mitigation strategies, and can be applied to a range of HAB species - those that produce saxitoxins, as well as those that produce other toxins that are nitrogen rich. Project results will be broadly disseminated through scientific papers, presentations at workshops, domestic and international conferences, and departmental seminars, and discussions with the media.
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.
Intellectual Merit:
A key outcome of this project was novel information regarding fractionation of nitrogen (N) by dinoflagellates when provided micromolar concentrations of NO3-, NH4+, urea, or a combination of the three. The results presented here for dinoflagellates are consistent with the isotopic fractionation published for other taxonomic groups, namely diatoms and coccolithophores, but add new insight into the biochemistry of N assimilation utilization for toxin production by dinoflagellates, and how preferential/multiple source uptake affects d15N.
Additionally, our data suggest that understanding the dominant N chemical forms in a system is important for management, i.e., as N chemical form controlled toxicity (but not growth rates), and when utilizing the N isotope ratio of particulate organic matter as a tracer of N source that fueled a dinoflagellate bloom. Toxin content and toxicity of A. fundyense were dependent upon the N chemical form being utilized, as well as the A. fundyense strain, suggesting that eutrophication and dominating strains can affect cellular toxicity of a bloom. High inputs of urea, for example, may lead to large blooms of A. fundyense with relatively low toxicity per cell. Causal analysis of nutrient pollution sources via stable isotopes will advance sustainability for the environment, economy, and human health by helping policy makers make informed decisions about point and nonpoint source pollution control in the United States. Nutrients are only one factor influencing bloom dynamics, but the relative importance of natural or anthropogenic nutrients in the development of a specific toxic bloom is necessary to predict future decadal, annual, and compositional shifts in algal blooms.
In summary, this study is the first to show the impact of N chemical form and N preference on N isotope fractionation during uptake by dinoflagellates. Overall, a better understanding of N metabolism within dinoflagellates and the role of N in the synthesis of toxins would enhance prediction and control of harmful algal blooms.
Broader Impacts:
This project supported the transition of female Lead PI-Smith from postdoc to new faculty member (tenure track) at the Virginia Institute of Marine Science (VIMS), VA. This transition included 1) the transfer of culturing techniques (A. fundyense) to VIMS, 2) the recruitment of the first graduate student, undergraduate, and staff member to the new lab, and 3) the successful completion of a M.S. degree by C. Taylor Armstrong under the new faculty member.
C. Taylor Armstrong, a recent graduate (M.S.) of VIMS from the research program of PI-Smith, just defended her final thesis based solely on this NSF project. She begins her next step in her career in February 2017 as a Knauss Fellow with NOAA. Armstrong is currently converting her thesis to a publication. She presented her preliminary results at a national conference, 15-20 November 2015, in Long Beach, CA and expects to present a poster on her final results at ASLO, HI in March 2017.
The project has also forwarded the training of two undergraduates. In year one, we provided technical training to an undergraduate student, Jennifer Haskell from Northeastern University, in culturing techniques for Alexandrium, cell enumeration, toxin extraction and purification, preparation of samples and solvent for saxitoxin quantification by HPLC-FLD, and the analysis of 12 saxitoxin congeners. Haskell’s involvement in this project was part of her six-month REU co-op in the Anderson Lab, at Wood Hole Oceanographic Institution.
In year two and three, we brought on another undergraduate student, Shannon Jones, also an REU student from Northeastern University. Jones continued the culturing work started by the previous intern, and then took on more independent tasks, such as helping in the development of field sampling protocols, processing of samples post-collection, leading the weekly sampling for this project in Mill Pond and Salt Pond, participating in week-long research cruises in the Gulf of Maine, data management, and sample processing and storage. Through this co-op experience, Jones learned new skills in culturing at VIMS, field sampling on small boats and larger vessels, and laboratory techniques associated with phytoplankton extraction and toxin quantification.
Last Modified: 01/29/2017
Modified by: Juliette L Smith
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