| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | January 23, 2017 |
| Latest Amendment Date: | June 4, 2019 |
| Award Number: | 1657727 |
| 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: | February 1, 2017 |
| End Date: | January 31, 2021 (Estimated) |
| Total Intended Award Amount: | $523,940.00 |
| Total Awarded Amount to Date: | $523,940.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
266 WOODS HOLE RD WOODS HOLE MA US 02543-1535 (508)289-3542 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
183 Oyster Pond Road Woods Hole MA US 02543-1501 |
| 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): | 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
Chemical and biological processes that occur in and on the seafloor can create chemical exchange of elements with seawater and make significant contributions to carbon and nutrient cycling in shallow coastal systems. However, these processes are exceedingly difficult to measure directly in the ocean, with no satisfactory methods currently available to quantify their full impact. The researchers undertaking this project have developed a unique, field instrument referred to as the Eddy Covariance H+ and O2 Exchange System (ECHOES). These novel measurements of hydrogen ion (H+) and oxygen (O2) exchange between the seafloor and the overlying seawater will allow unique, direct evaluation of the important linked biological and chemical reactions. Data from ECHOES will transform understanding of the potentially critical contribution of seafloor processes to the resilience of coastal ecosystems experiencing rapid changes in seawater chemistry. Results from this project will provide critical data for improved models of the consequences of coastal acidification. Additionally, this project will fund an early career scientist and the mentorship of undergraduate students in ocean science research through the Woods Hole Oceanographic Institute's Summer Student Fellowship Program.
Laboratory experiments have successfully examined the benthic response of individual organisms and chemical reactions to stress related to changing seawater chemistry but the integrated response of intact ecosystems has been very difficult to quantify due to unsatisfactory methods for in situ measurements of the required suite of biogeochemical fluxes. This deployment of ECHOES at a variety of carbonate-dominated seafloor sites in Bermuda is a pioneering effort to simultaneously measure net community production (NCP) and net community calcification (NCC). The study will focus on traditionally difficult-to-study systems including complex reefs, vertical seagrass canopies, and bare permeable sediments, evaluating diel variability, patchiness, and the impact of upstream fluxes on downstream ecosystems. Important biogeochemical parameters (e.g. pH, CO2, O2, alkalinity, etc.) in these productive shallow environments can experience daily fluctuations over a greater dynamic range than 100-year model projections for the open ocean due to increasing atmospheric CO2. Therefore, the novel field data generated by this research will help define the potentially critical and heretofore ill-defined role for shallow, productive carbonate sediments in predictive models of ecosystem response to ocean acidification.
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.
Biogeochemical processes can be estimated by the exchange of vital tracers between the seafloor, overlying water, and the atmosphere and are paramount to understanding global biogeochemical cycling. Techniques that measure water transport and tracers of these processes (here oxygen and pH) have revolutionized how these exchanges are studied, and how they impact local water quality, productivity, and nutrient cycling. Through measurements of oxygen concentration and pH, and their transport by water movement, their exchange can be determined.
This project used the newly developed eddy covariance hydrogen ion and oxygen exchange systems (ECHOES) to evaluate the coupled benthic processes of photosynthesis / respiration and dissolution / calcification at an ecosystem scale on the Bermuda platform and in the Florida Keys, to quantify their contribution to carbon cycling, water column chemistry and the effects of adjacent benthic communities. The co-measured hydrogen ion (or pH) and oxygen exchange rates (in combination with discrete measurements of carbonate chemistry) provided a comprehensive analysis of the total ecosystem carbon cycling and allowed for a truly in situ examination of the natural drivers of carbon cycling, metabolism, and calcification. These results revealed interactions between these processes through high frequency, ecosystem scale measurements that are now possible with the ECHOES. The influence of benthic processes on shallow coastal waters highlighted the multiple parameter dependency (residence time, benthic community, light) of the local carbonate chemistry and the potential resilience of dynamic coastal environments to changing ocean conditions.
Eddy Covariance techniques were originally developed to examine exchange between the land and atmosphere (e.g. carbon dioxide flux towers, or eddy covariance flux towers), but applying these techniques to aquatic ecosystems presented challenges due to surface waves that were present in the shallow aquatic ecosystems where these aquatic techniques are commonly applied. Waves caused errors in the sensors used to measure water transport and tracer concentrations, and presented significant challenges for applying these atmospheric techniques underwater. This research developed new guidelines for these aquatic exchange measurements that required a change in how measurements were conducted and analyzed, to allow for tracer exchange measurements in the presence of waves. These new guidelines also now allow for new sensors that were previously incompatible, expanding the applications of the eddy covariance technique to new scientific research questions.
Last Modified: 06/16/2021
Modified by: Matthew Long
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