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Award Detail

Doing Business As Name:Woods Hole Oceanographic Institution
  • Anne Cohen
  • (508) 289-2958
  • Steven J Lentz
  • Kathryn Shamberger
Award Date:09/20/2012
Estimated Total Award Amount: $ 695,322
Funds Obligated to Date: $ 695,322
  • FY 2012=$695,322
Start Date:09/01/2012
End Date:02/29/2016
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.050
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Toward Predicting the Impact of Ocean Acidification on Net Calcification by a Broad Range of Coral Reef Ecosystems: Identifying Patterns and Underlying Causes
Federal Award ID Number:1220529
DUNS ID:001766682
Parent DUNS ID:001766682
Program:CRI-Ocean Acidification

Awardee Location

County:Woods Hole
Awardee Cong. District:09

Primary Place of Performance

Organization Name:Woods Hole Oceanographic Institution
Street:360 Woods Hole Road
City:Woods Hole
County:Woods Hole
Cong. District:09

Abstract at Time of Award

Intellectual Merit: Much of our understanding of the impact of ocean acidification on coral reef calcification comes from laboratory manipulation experiments in which reef organisms are removed from their natural habitat and reared under conditions of calcium carbonate saturation (Omega) predicted for the tropical oceans at the end of this century. By comparison, there is a paucity of in situ data describing the sensitivity of coral reef ecosystems to changes in calcium carbonate saturation. Yet emerging evidence suggests there may be critical differences between the calcification response of organisms in culture and the net calcification response of a coral reef ecosystem, to the same degree of change in calcium carbonate saturation. In the majority of cases, the sensitivity of net reef calcification to changing calcium carbonate saturation is more severe than laboratory manipulation experiments predict. Clearly, accurate predictions of the response of coral reef ecosystems to 21st century ocean acidification will depend on a robust characterization of ecosystem-scale responses and an understanding of the fundamental processes that shape them. Using existing data, the investigators show that the sensitivity of coral reef ecosystem calcification to Delta calcium carbonate saturation conforms to the empirical rate equation R=k(Aragonite saturation state -1)n, which also describes the relationship between the rate of net abiogenic CaCO3 precipitation (R) and the degree of aragonite supersaturation (Aragonite saturation state-1). By implication, the net ecosystem calcification (NEC) response to ocean acidification is governed by fundamental laws of physical chemistry and is potentially predictable across space and time. When viewed this way, the existing, albeit sparse, dataset of NEC reveals distinct patterns that, if verified, have important implications for how different coral reef ecosystems will respond to 21st century ocean acidification. The investigators have outlined a research program designed to build on this proposition. The project expands the currently sparse dataset of ecosystem-scale observations at four strategically placed reef sites, enabling us to test the following hypotheses: 1. The sensitivity ("n" in the rate equation) of coral reef ecosystem calcification to Delta Aragonite saturation state decreases with decreasing Aragonite saturation state. By implication, the rate at which reef calcification declines will slow as ocean acidification progresses over the course of this century. 2. The energetic status of the calcifying community is a key determinant of absolute rates of net ecosystem calcification ("k" in the rate equation), which, combined with n, defines the Aragonite saturation state value at which NEC approaches zero. By implication, the shift from net calcification to net dissolution will be delayed in healthy, energetically replete coral reef ecosystems and accelerated in perturbed, energetically depleted ecosystems. 3. The calcification response of individual colonies of dominant reef calcifiers (corals and algae) is weaker than the measured ecosystem-scale response to the same change in Aragonite saturation state. By implication, processes not adequately captured in laboratory experiments, such as bioerosion and dissolution, will play an important role in the coral reef response to ocean acidification. Broader Impacts: Ocean acidification threatens the livelihoods of 500 million people worldwide who depend on coral reefs to provide habitable and agricultural land, food, building materials, coastal protection and income from tourism. Yet data emerging from ocean acidification (OA) studies point to critical gaps in our knowledge of reef ecosystem-scale responses to OA that currently limit our ability to predict the timing and severity of its impact on different reefs in different parts of the world. Using existing data generated by the investigators and others, this project will address a series of related hypotheses, which, if verified by the research, will have an immediate, direct impact on predictions of coral reef resilience in a high CO2 world. This project brings together expertise in coral reef biogeochemistry, chemical oceanography and physical oceanography to focus on a problem that has enormous societal, economic and conservation relevance. Support is provided for a young investigator, undergraduate and minority student will participate in research through the WHOI Summer Fellowship Program, the Woods Hole Sea Education Association and PEP programs, and a burgeoning collaboration will be enhanced between the PIs and Pacific Island conservation groups and stakeholders whose goal it is to ensure that conservation decisions are grounded in scientific data. Results of the study will be presented at national and international meetings and workshops and disseminated in a timely manner through peer-reviewed publications. All data produced through this program will be archived in the Biological and Chemical Oceanographic Data Management Office (BCO-DMO) and the Pangaea Open Access library.

Publications Produced as a Result of this Research

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DeCarlo T.M., Gaetani G.A., Cohen A.L., Foster G.L., Alpert A.E., & J. Stewart "Coral Sr-U Thermometry" Paleoceanography, v.31, 2016, p.626.

Lentz, S. J., J. H. Churchill, K. A. Davis, J. T. Farrar, J. Pineda, V. Starczak "The characteristics and dynamics of wave-driven flow across a platform coral reef in the Red Sea" JGR, v.121, 2016, p.1360. doi:10.1002/2015JC011141 

DeCarlo, T.M, Karnauskas, K.B., Davis, K.A., and G.T.F. Wong "Climate modulates internal wave activity in the Northern South China Sea" Geophysical Research Letters, v., 2015, p..

Alin, Simone R., Russell E. Brainard, Nichole Price, Jan Newton, Anne Cohen, William T. Peterson, Eric Heinen DeCarlo, Elizabeth H. Shadwick, Scott Noakes, Nina Bednarsek "Characterizing the natural system: Toward sustained, integrated coastal ocean health observing systems to facilitate resource management and decision support" Oceanography, v.28, 2015, p.92. doi:10.5670/oceanog.2015.34 

Barkley, H.C., Cohen, A.L., Golbuu, Y., Starczak, V.R., Shamberger, K.E.F., and DeCarlo, T.M. "Changes in coral reef communities across a natural gradient in ocean acidification" Science Advances, v., 2015, p.. doi:1:e1500328 

Thomas M. DeCarlo, Anne L. Cohen, Hannah C. Barkley, Quinn Cobban, Charles Young, Kathryn E. Shamberger, Russell E. Brainard, and Yimnang Golbuu "Coral macrobioerosion is accelerated by ocean acidification and nutrients" Geology, v., 2014, p.. doi:doi:10.1130/G36147.1 | Published 

Lentz, S. J., J. H. Churchill, K. A. Davis, J. T. Farrar "Surface gravity wave transformation across a platform coral reef in the Red Sea" JGR, v.121, 2016, p.693. doi:10.1002/2015JC011142 

DeCarlo T.M., Karnauskas K.B., Davis K.A., & G.T.F. Wong "Climate modulates internal wave activity in the Northern South China Sea" Geophysical Research Letters, v.42, 2015, p.831.

DeCarlo, T.M, Cohen, A.L., Barkley, H.C., Cobban, Q., Young, C., Shamberger, K.E., Brainard, R.E., & Y. Golbuu. "Coral macrobioerosion is accelerated by ocean acidification and nutrients." Geology, v., 2014, p.. doi:doi:10.1130/G36147.1 

DeCarlo T.M., Cohen A.L., Barkley H.C., Cobban Q., Young C., Shamberger K.E., Brainard R.E., & Y. Golbuu "Coral macrobioerosion is accelerated by ocean acidification and nutrients" Geology, v.43, 2015, p.7.

Edmunds Peter J, Steeve Comeau, Coulson Lantz, Andreas Andersson, Cherie Briggs, Anne Cohen, Jean-Pierre Gattuso, John Grady, Kevin Gross, Maggie Johnson, Erik Muller, Justin B Ries, Sylvie Tambutté, Eric Tambutté, Alex Venn, and Robert C. Carpenter. "Integrating the effects of ocean acidification across functional scales on tropical coral reefs" Biosciences, v.66, 2016, p.350. doi:10.1093/biosci/biw023 

H.C. Barkley, A.L. Cohen, Y. Golbuu, V.R. Starczak, T.M. DeCarlo, K.E.F. Shamberger "Changes in coral reef communities across a natural gradient in seawater pH" Science Advances, v.1, 2015, p.e1500328.

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.

Coral reef ecosystems support the livelihoods of 500 million people worldwide, provide coastline protection worth billions of dollars, and provide habitat for 25% of all marine species. Coral reefs are built by organisms, mainly corals and coralline algae that produce calcium carbonate (CaCO3) skeletons. Healthy coral reefs produce more CaCO3 than they lose to waves, storms and bioerosion, a delicate balance that has been maintained for thousands of years. Anthropogenic climate change threatens this balance. Laboratory experiments show that ocean acidification, the decline in ocean pH caused by absorption of anthropogenic CO2, makes it more difficult for organisms to produce CaCO3 while making CaCO3 skeletons more susceptible to erosion and dissolution.

We investigated the main factors controlling rates of CaCO3 production by corals and coral reef communities. First, we quantified rates of calcification and bioerosion in situ, by massive Porites corals across the natural pH, temperature and productivity gradient of the tropical Pacific basin.  We found that coral calcification and bioerosion correlate strongly with water column primary productivity, represented by chlorophyll a concentrations. Corals in highly productive waters calcify faster, but they also erode faster.  Both calcification and erosion exhibit sensitivity to the gradient in ocean pH. Calcification slows and bioerosion rates increase with decreasing pH. However, the influence of pH is weaker than the influence of primary productivity. Overall, rates of CaCO3 production by coral colonies is highest on reefs where productivity and pH are high; conversely, rates of bioerosion are highest when productivity is high and pH is low. Nevertheless today, Porites coral calcification rates still exceed bioerosion rates by a wide margin.

We then measured Net Ecosystem Calcification (NEC) by three different reef communities to evaluate the main controls on net calcification on the reef scale. NEC is the balance between how much CaCO3 is produced by reef organisms and how much is dissolved away, over a period of several days.  We replicated measurements of NEC by the same reef community in different weeks, different seasons and different years. We found large changes in NEC rates between different deployments at the same site, in the absence of any changes in seawater pH. Lowest NEC rates were recorded at the lowest pH reef on Palau. However, we did not find a correlation between pH and NEC across our three study sites. We compiled our NEC data together with those generated by other groups on other reefs around the world (n=31). We found no relationship between NEC and the pH of the source water feeding the reef.  Together, these observations indicate that currently, ocean pH is not a good predictor of net CaCO3 production on coral reefs in nature.

Key insights into the drivers of NEC come from our study on Dongsha Atoll, northern South China Sea, where we made hourly measurements of NEC and NEP (Net Ecosystem Productivity) on the 3-km wide reef flat, over two four-day deployments. Here, NEC rates were the highest ever recorded on a reef, anywhere, despite "normal" ocean pH ~8-8.1 values and relatively low coral cover of ~21%.  However, hourly NEC and NEP on the reef flat were tightly correlated: when productivity was high, calcification was high too. One of our deployments coincided with a transient coral bleaching event caused by anomalously high water temperatures. During bleaching, NEP declined and NEC rates declined also, in the absence of any change in the pH of the open ocean source water to the reef.

Our results highlight the important role of primary productivity for calcification by corals and coral reefs alike. While the mechanisms underlying this link are not yet clear, it is possible that productivity, by coral symbionts, benthic algae, and reef phytoplankton, modulate the pH of the environment in which calcification occurs, both within the coral itself and on the reef. The implication is that processes that modulate the pH of seawater on the reef may be more, or as important, as the pH of the open ocean source water to the reef, in determining the acidification of coral reef ecosystems through the 21st century. 

If future work supports our findings, anthropogenic climate changes that influence coral, coral reef and open ocean productivity will have a major impact on the persistence of coral reefs.

13 peer-reviewed papers, one publically-available software program (coralCT), post-doctoral research, 4 PhD theses, one senior thesis and a PBS NOVA documentary on ocean acidification were supported by this award.

Last Modified: 08/22/2016
Modified by: Anne Cohen

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