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Minimize RSR Award Detail

Research Spending & Results

Award Detail

  • Leah B Reidenbach
Award Date:06/24/2015
Estimated Total Award Amount: $ 5,070
Funds Obligated to Date: $ 5,070
  • FY 2015=$5,070
Start Date:06/01/2015
End Date:05/31/2016
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.079
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:EAPSI: Effects of Ocean Acidification and Eutrophication on the Green Macroalgae Ulva spp
Federal Award ID Number:1515267
Program Officer:
  • Anne Emig
  • (703) 292-7241

Awardee Location

Awardee Cong. District:09

Primary Place of Performance

Organization Name:Institute for Marine and Antarctic Studies
City:Battery Point

Abstract at Time of Award

This award supports research that will investigate how the changing marine environment affects the growth rate of a weedy macroalgae, Ulva spp. Two factors that may act synergistically on Ulva spp. growth rates are ocean acidification and eutrophication. Ocean acidification is caused by increasing absorption of atmospheric carbon dioxide in seawater, which changes water chemistry and lowers pH. Eutrophication is caused mainly by human activities increasing the nutrients in seawater. Eutrophication alone is known to cause green-tide blooms of Ulva spp., and it is predicted that ocean acidification may increase growth rates of Ulva spp. because of increased carbon dioxide availability. How these two factors affect the growth rate when occurring simultaneously has not been thoroughly investigated. A state of the art ocean acidification incubation system will be used to investigate the synergy of these effects at the University of Tasmania in collaboration with Dr. Catriona Hurd, an expert in macroalgal physiology. Ocean acidification is occurring worldwide and eutrophication occurs near heavily populated coasts. This project will increase our ability to make predictions about the abundance of Ulva spp. in future marine environments. Ocean acidification changes seawater chemistry by increasing the CO2(aq) concentration, which is the form of carbon used by the photosynthetic substrate Rubisco. Presently, dissolved CO2 in water makes up less than 1% of the total inorganic carbon in seawater. The more abundant form of inorganic carbon is bicarbonate (H2CO3). Most macroalgae can utilize both forms of inorganic carbon for photosynthesis, however the uptake of CO2 is less energetically costly as it occurs via passive diffusion through the cell membrane. Uptake of H2CO3 requires energy for carbon uptake, so we predict that the increase in CO2 may result in energetic savings that can be allocated to growth and nutrient uptake. This project will investigate if increasing dissolved CO2 will increase the ability of Ulva spp. to perform nutrient uptake of nitrogen. The results of this experiment will inform us about how human activities and environmental factors interact in future climate conditions for marine primary producers. This NSF EAPSI award supports the research of a U.S. graduate student and is funded in collaboration with the Australian Academy of Science.

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.

Ocean acidification and coastal nutrient enrichment may have synergistic effects on the physiological responses of macroalgae in today’s changing ocean environment. Understanding the biological impacts of these environmental changes has become increasingly important within the past few decades as carbon dioxide (CO2) continues to be released into the atmosphere, absorbed in the oceans, and decreasing oceanic pH. This EAPSI project aimed to quantify the effects of nutrient enrichment and ocean acidification on the green macroalga Ulva sp. using a state-of-the-art ocean acidification incubation station with a full cross of three levels of CO2 enrichment and two levels of nutrient enrichment. Ulva sp. were incubated for one week. Measurements of growth rates, nutrient uptake rates, and photosynthetic parameters were measured at the end of the experiment.

Growth rates were positively affected by nutrient enrichment, but not CO2 enrichment. Photosynthetic rates were unaffected by nutrient and CO2 enrichment. Nutrient uptake was different among nutrient treatments, and there was an interactive effect of CO2 enrichment and nutrient enrichment. The interaction increased the differences between nutrient uptake rates in the ambient and enrichment nutrient treatments at the intermediate level on CO2 enrichment.

In summary, nutrient enrichment will continue to be the primary driver of green macroalgae blooms. The research on the effects of CO2 enrichment (ocean acidification) should be studied under different environmental variables to better understand physiological processes in macroalgae under CO2 enrichment. This project used a non-calcifying macroalga Ulva sp., to provide a basis for understanding how ocean acidification and eutrophication will affect oceanic primary producers, such as opportunistic macroalgae species, which informs our knowledge on the future of coastal ecosystems.



Last Modified: 03/16/2016
Modified by: Leah B Reidenbach

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