| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | August 4, 2017 |
| Latest Amendment Date: | August 4, 2017 |
| Award Number: | 1737096 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Daniel J. Thornhill
dthornhi@nsf.gov (703)292-8143 OCE Division Of Ocean Sciences GEO Directorate For Geosciences |
| Start Date: | September 1, 2017 |
| End Date: | August 31, 2021 (Estimated) |
| Total Intended Award Amount: | $203,157.00 |
| Total Awarded Amount to Date: | $203,157.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
450 JANE STANFORD WAY STANFORD CA US 94305-2004 (650)723-2300 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
Stanford CA US 94305-2004 |
| 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
Kelp forest ecosystems are of ecological and economic importance globally and provide habitat for a diversity of fish, invertebrates, and other algal species. In addition, they may also modify the chemistry of surrounding waters. Uptake of carbon dioxide (CO2) by giant kelp, Macrocystis pyrifera, may play a role in ameliorating the effects of increasing ocean acidity on nearshore marine communities driven by rising atmospheric CO2. Predicting the capacity for kelp forests to alter seawater chemistry requires understanding of the oceanographic and biological mechanisms that drive variability in seawater chemistry. The project will identify specific conditions that could lead to decreases in seawater CO2 by studying 4 sites within the southern Monterey Bay in Central California. An interdisciplinary team will examine variations in ocean chemistry in the context of the oceanographic and ecological characteristics of kelp forest habitats. This project will support an early career researcher, as well as train and support a postdoctoral researcher, PhD student, thesis master's student, and up to six undergraduate students. The PIs will actively recruit students from underrepresented groups to participate in this project through Stanford University's Summer Research in Geosciences and Engineering (SURGE) program and the Society for Advancement of Hispanics/Chicanos and Native Americans in Science (SACNAS). In addition, the PIs and students will actively engage with the management community (Monterey Bay National Marine Sanctuary and California Department of Fish and Wildlife) to advance products based on project data that will assist the development of management strategies for kelp forest habitats in a changing ocean.
This project builds upon an extensive preliminary data set and will link kelp forest community attributes and hydrodynamic properties to kelp forest biogeochemistry (including the carbon system and dissolved oxygen) to understand mechanistically how giant kelp modifies surrounding waters and affects water chemistry using unique high-resolution measurement capabilities that have provided important insights in coral reef biogeochemistry. The project sites are characterized by different oceanographic settings and kelp forest characteristics that will allow examination of relationships between kelp forest inhabitants and water column chemistry. Continuous measurements of water column velocity, temperature, dissolved oxygen, pH, and photosynthetically active radiation will be augmented by twice-weekly measurements of dissolved inorganic carbon, total alkalinity, and nutrients as well as periods of high frequency sampling of all carbonate system parameters. Quantifying vertical gradients in carbonate system chemistry within kelp forests will lead to understanding of its dependence on seawater residence time and water column stratification. Additional biological sampling of kelp, benthic communities, and phytoplankton will be used to 1) determine contributions of understory algae and calcifying species to bottom water chemistry, 2) determine contributions of kelp canopy growth and phytoplankton to surface water chemistry and 3) quantify the spatial extent of surface chemistry alteration by kelp forests. The physical, biological, and chemical data collected across multiple forests will allow development of a statistical model for predictions of kelp forest carbonate system chemistry alteration in different locations and under future climate scenarios. Threshold values of oceanographic conditions and kelp forest characteristics that lead to alteration of water column chemistry will be identified for use by managers in mitigation strategies such as targeted protection or restoration.
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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.
Kelp forests are among the world's most productive marine ecosystems. They are widespread in the coastal ocean, especially in temperate and sub-polar environments. Because they are so highly productive they support many other marine organisms, including fish, shellfish, and marine mammals. Their hyper-productivity also suggests that they may be able to locally reduce the impacts of ocean acidification (OA). Some coastal organisms are very sensitive to increasing seawater acidity caused by increasing levels of carbon dioxide. Shellfish larvae, in particular, are already known to be impacted by OA. We explored the possible that hyper-productivity by growing kelp may reduce this effect near to the kelp. We did so by deploying a large array of instruments that measure water column properties inside and outside of a kelp forest in Monterey Bay, California. These instruments recorded seawater circulation oxygen levels, and acidity, at minute-to-minute to day-to-day to week-to-week timescales during two summers. We saw clear differences in water chemistry between the arrays inside and outside of the kelp forest as well as between surface waters and near-bottom waters.
Surface water pH was elevated inside the kelp compared to outside, suggesting that the kelp canopy locally decreased surface ocean acidification. But we observed the greatest acidification stress deeper in the water column where levels of carbon dioxide (partial pressure) reached levels as high as 1,300 μatm, about 3 times the partial pressure of carbon dioxide in air. In these acidic waters, aragonite undersaturation (ΩAr < 1) occurred on several occasions. Aragonite is an important mineral grown by developing shellfish larvae and undersaturation of the local seawater would cause stress. At this site, kelp canopy modification of seawater properties, and thus any ameliorating effect against acidification, is greatest in a narrow band of surface water, whereas the greatest acidification stress is located well below the surface canopy. The spatial disconnect between stress exposure at depth and reduction of acidification stress at the surface warrants further assessment of utilizing kelp forests as provisioners of local OA mitigation.
Last Modified: 09/09/2022
Modified by: Robert B Dunbar
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