| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | January 28, 2014 |
| Latest Amendment Date: | January 28, 2014 |
| Award Number: | 1357168 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Michael Sieracki
OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | April 1, 2014 |
| End Date: | December 31, 2018 (Estimated) |
| Total Intended Award Amount: | $420,515.00 |
| Total Awarded Amount to Date: | $420,515.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
302 BUCHTEL COMMON AKRON OH US 44325-0001 (330)972-2760 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
302 Bucthel Common Akron OH US 44325-0001 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | BIOLOGICAL 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
Overview: This project will conduct a set of field/laboratory experiments to address the following hypotheses with respect to microzooplankton (consumers between 20-200 µm) and diatom- produced polyunsaturated aldehydes:
I. Aldehydes will impair microzooplankton herbivory on diatoms and non-diatom phytoplankton.
II. Aldehydes will reduce the growth rates of microzooplankton and non PUA-producing phytoplankton.
III. In the presence of aldehyde-producing diatoms, copepods will switch to microzooplankton, whereas non- (mildly)- toxic diatoms will be an important food source for copepods.
IV. The effects of aldehydes on microzooplankton and copepods will depend on the grazers' prior exposure to PUA.
The experiments will include natural plankton, captured copepods, cultured Skeletonema marinoi (SM), including its aldehyde-producing strain, and synthetic aldehydes. To gain insights into complex interactions within planktonic communities, detailed information on their composition, abundance, and dynamics will be obtained using microscopy, flow-cytometry, and cytological methods. This approach will allow the PIs to draw conclusions about the role of diatom-produced aldehydes in phytoplankton-microzooplankton- copepod trophic interactions. The PIs will coordinate efforts and exchange information with the PUA study group at the Stazione Zoologica Anton Dohrn (Naples, Italy).
Intellectual merit: Diatoms are dominant autotrophic plankton in the ocean. Recent evidence indicates that microzooplankton are the dominant herbivores, whereas copepods often rely on microzooplankton as food, except during peak diatom production. The ability of microzooplankton to feed on large diatoms and grow as fast as their algal prey leads to the question of what allows diatoms to escape microzooplankton grazing control during the initial phases of their blooms and maintain the blooms until nutrient resources are depleted? Allelopathy is wide spread among phytoplankton. The cosmopolitan bloom-forming SM produces several aldehydes and has become a model organism in plankton allelopathy studies. Most studies on diatom cytotoxicity have been dedicated to inhibitory effects on reproduction and development of marine invertebrates, whereas surprisingly little information exists on its impact on key diatom grazers, microzooplankton. Preliminary results in the Chesapeake Bay show that aldehydes may induce cascading effects within planktonic communities. The proposed study will: (1) Improve our knowledge of the critical diatom-microzooplankton-copepod links in the coastal ocean; (2) Generate novel data on the effects of allelopathy on marine food webs; (3) Contribute to our understanding of broader patterns of marine ecosystems by comparing plankton structure and dynamics in the temperate Atlantic waters; (4) Advance biological oceanography through international collaboration.
Broader Impacts: One post-doctoral fellow, two graduate students and several undergraduate students at the Universities of Akron and Maryland will be trained as a result of this project. The project will attract motivated minority students into the program. The research will be extended to students in grades 7-12 and teachers via an interactive distance learning series in collaboration with the WVIZ Ideastream network. The PIs will continue an existing outreach partnership with the Great Lakes Science Center, where a recent electronic presentation dedicated to Arctic change and NSF-sponsored research was seen by ca. 45,000 visitors. The PIs will also work with the Cleveland Museum of Natural History to develop public programs, and with the National Inventors Hall of Fame STEM Middle School to develop a curriculum focused on polar research. Curriculum modules will be available as free downloads from a dedicated website. Broader Impacts, LLC, will evaluate these education and outreach activities.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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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.
Spring algal blooms are important mechanisms to jumpstart biological production in marine and estuarine systems each year. Single-celled marine algae, collectively known as phytoplankton, create these blooms and are eaten by microscopic animals called zooplankton; in turn, zooplankton are eaten by fish. These trophic interactions determine marine food web productivity. However, some algae produce toxic chemicals to deter their grazers and suppress competitors for resources in the process called allelopathy Diatoms are an important group of phytoplankton that are known to produce these chemicals. They also are dominant bloom-forming organisms in the spring in many coastal and estuarine systems. Previous work has examined the toxicity of these chemicals, called polyunsaturated aldehydes, or PUA, on the development of marine invertebrate animals and in particular on tiny crustaceans called copepods. Copepods are probably the most numerous animal on earth, found in almost every aquatic environment. Much less work has been done to examine how these chemicals affect even smaller, single-celled zooplankton known as heterotrophic protists. Recent studies show that these microorganisms are the most important grazers of phytoplankton, responsible for more than half of the feeding on algae in the ocean, and they are also important food for copepods.
The goal of this project was to determine how PUA affected the growth and feeding of the heterotrophic protists and the overall plankton food web including the algae, protists, and animal zooplankton. We hypothesized that when algae that produce the PUA were present, it would decrease the feeding by both the heterotrophic protists and the copepods, which would allow the algae populations to grow faster and create bigger blooms. To test our hypothesis, we conducted a number of field and laboratory experiments in and around the Chesapeake Bay, and in the Adriatic Sea (the Mediterranean). These locations were chosen because large blooms of diatoms known to produce PUA occur there regularly. We collected water and measured how much the algae and heterotrophic protists grew with and without PUA added to the water, and how much the heterotrophic protists and copepods ate. We were also able to look at swimming patterns of heterotrophic protists exposed to PUA, and we were able to conduct some experiments, where we also added not only the chemical PUA but also some diatoms that produced PUA that we grew in the lab. In addition, we examined food web interactions in the high Arctic, where diatoms and other algae also form dense blooms when the sea ice starts melting in the spring.
Our findings show for the first time that when dissolved PUA is present in seawater, the heterotrophic protists eat fewer diatoms, more other algae, and they grew slower. In addition, in the presence of PUA copepods switch their feeding preference to eat more heterotrophic protists, although they did not stop eating the algae completely. Some of these patterns are species-specific to both heterotrophic protists and copepods, with different taxa showing stronger responses than others to the addition of PUA. Overall these findings illustrate a means that algae may be affecting their grazers and competitors for resources in a way that is beneficial to the algae, allowing it to grow faster and create larger blooms (see the figure on the right).
This collaborative project involved a diverse group of scientists at different stages of their careers, primarily from the University of Akron (UA) and the University of Maryland Center for Environmental Sciences (UMCES), but also from Woods Hole Oceanographic Institution and Rider University. The work in Italy was conducted with the help of collaborators from ISMAR CNR in Venice, SZN in Naples, and Marche Polytechnic University in Ancona, whereas the work in the Arctic was supported by our colleagues from the University of Tromso in Norway. The project has produced a number of peer-reviewed papers describing the findings and interpreting the data, and the findings from this work was included in K-12 STEM learning programs conducted at the UMCES and UA.
Last Modified: 05/31/2019
Modified by: Peter J Lavrentyev
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