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Award Detail

Doing Business As Name:University of Miami
  • Andrew C Baker
  • (305) 421-4642
Award Date:01/09/2014
Estimated Total Award Amount: $ 638,787
Funds Obligated to Date: $ 638,787
  • FY 2014=$638,787
Start Date:02/01/2014
End Date:01/31/2019
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:New insights into the response of reef corals to climate change using the symbiont to host cell ratio as a metric of bleaching susceptibility
Federal Award ID Number:1358699
DUNS ID:152764007
Parent DUNS ID:004146619
Program Officer:
  • Daniel J. Thornhill
  • (703) 292-8143

Awardee Location

City:Key Biscayne
County:Key Biscayne
Awardee Cong. District:27

Primary Place of Performance

Organization Name:University of Miami - RSMAS
County:Key Biscayne
Cong. District:27

Abstract at Time of Award

The long-term future of reef ecosystems depends on the continued persistence of corals as essential habitat builders. Environmental threats facing coral reefs globally include chronic and acute thermal stress (which can result in ?coral bleaching" as a result of the expulsion of their symbiotic algae), increasing CO2, and nutrient pollution. This project will assess the independent and interactive effects of these stressors using a new molecular based technique showing that coral bleaching susceptibility depends on the symbiont:host (S:H) cell ratio in coral tissues. Corals with higher ratios (more symbionts) are predicted to be more susceptible to thermal stress, suggesting that abiotic factors that affect symbiont densities can directly influence thermal tolerance. This new metric of symbiont density is of physiological relevance and has already revealed patterns that differ from currently used metrics, thus providing new insights into the dynamics of these symbioses. This project will also continue the development and application of these methods to further our understanding of the ecology of coral-algal symbioses, while helping to elucidate the responses of these critical ecosystem engineers to complex changes in their environment. The proposed activities will help us understand how tradeoffs in the regulation of symbiotic partners respond to the environment and relate to the differential susceptibility of corals to environmental stress. The development of molecular assays to quantify symbiont abundance represents a technical resource that will help advance the field of coral ecology. This project will train a postdoctoral researcher and several students (graduate and undergraduate), helps expand a new state-of-the-science running seawater laboratory, establishes a new coral nursery as an educational resource, and will be incorporated into ongoing activities in K-12 outreach and involvement with mass media for broader public outreach.

Publications Produced as a Result of this Research

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Cunning R, Silverstein RN, Baker AC "Investigating the causes and consequences of symbiont shuffling in a multi-partner reef coral symbiosis under environmental change" Proceedings of the Royal Society B, v.282, 2015, p.282 20141. doi:10.1098/rspb.2014.1 

Aswani S, Mumby PJ, Baker AC, Christie P, McCook LJ, Steneck RS, Richmond RH "=Scientific frontiers in the management of coral reefs" Frontiers in Marine Science, v.2, 2015, p.. doi:10.3389/fmars.2015.00050 

Silverstein RN, Cunning R, Baker AC "Tenacious D: Symbiodinium in clade D remain in reef corals at both high and low temperature extremes despite impairment." Journal of Experimental Biology, v.220, 2017, p.11.

Towle EK, Baker AC, Langdon C "Preconditioning to high CO2 exacerbates the response of the Caribbean branching coral Porites porites to high temperature stress." Marine Ecology Progress Series, v.546, 2016, p.75.

Lirman D, Schopmeyer S, Galvan V, Drury C, Baker AC, Baums IB "Growth dynamics of the threatened Caribbean staghorn coral Acropora cervicornis: Influence of host genotype, symbiont identity, colony size, and environmental setting." PLoS One, v., 2014, p.. doi:10.1371/journal.pone.0107253 

De Souza JN, Nunes FLD, Zilberberg C, Sanchez JA, Migotto AE, Hoeksema BW, Serrano XM, Baker AC, Lindner A "Contrasting patterns of connectivity among endemic and widespread fire coral species (Millepora spp.) in the tropical Southwestern Atlantic." Coral Reefs, v., 2017, p..

Cunning R, Silverstein RN, Barnes BB, Baker AC "Extensive coral mortality and critical habitat loss following dredging and their association with remotely-sensed sediment plumes." Marine Pollution Bulletin, v.145, 2019, p.185.

Okazaki RR, Towle EK, van Hooidonk R, Mor C, Winter RN, Piggot AM, Cunning R, Baker AC, Klaus JS, Swart PK, Langdon C "Species-specific responses to climate change and community composition determine future calcification rates of Florida Keys reefs." Global Change Biology, v.23, 2016, p.1023.

Silverstein RN, Cunning R, Baker AC "Change in algal symbiont communities after bleaching, not prior heat exposure, increases heat tolerance of reef corals." Global Change Biology, v., 2015, p.. doi:10.1111/gcb.12706 

Louis YD, Bhagooli R, Kenkel CD, Baker AC, Dyall SD "Gene expression biomarkers of heat stress in scleractinian corals: Promises and limitations." Comparative Biochemistry and Physiology, part C, v.191, 2017, p.63.

Baker A "What is natural? Shifting baselines in marine conservation." Red Flag, v.8, 2014, p..

McIlroy SE, Gillette P, Cunning R, Klueter A, Capo T, Baker AC, Coffroth MA "The effects of Symbiodinium (Pyrrhophyta) identity on growth, survivorship, and thermal tolerance of newly settled coral polyps." Journal of Phycology, v.52, 2016, p.1114.

EK Towle, AM Palacio-Castro, AC Baker, C Langdon "Source location and food availability determine the growth response of Orbicella faveolata to climate change stressors." Regional Studies in Marine Science, v.10, 2017, p.107.

Cunning R, Baker AC "Not just who, but how many: The importance of partner abundance in reef coral symbioses." Frontiers in Microbiology, v.5, 2014, p.400.

Cunning R, Vaughan N, Gillette P, Capo T, Maté J, Baker AC "Dynamic regulation of partner abundance mediates response of reef coral symbioses to environmental change." Ecology, v., 2015, p..

Starger CJ, Erdmann MV, Toha AHA, Baker AC, Barber PH "Strong genetic structure among coral populations within a conservation priority region, the Bird's Head Seascape (Papua, Indonesia)." Frontiers of Biogeography, v.7, 2015, p.91.

Cunning R, Gillette P, Capo T, Galvez K, Baker AC "Growth tradeoffs associated with thermotolerant symbionts in the coral Pocillopora damicornis are lost in warmer oceans." Coral Reefs, v., 2014, p.. doi:10.1007/s00338-014-1216-4 

Cunning R, Silverstein RN, Baker AC "Symbiont shuffling linked to differential photochemical dynamics of Symbiodinium in three Caribbean reef corals." Coral Reefs, v., 2018, p.. doi:10.1007/s00338-017-1640-3 

Wirshing HH, Baker AC "On the problem of distinguishing species in mixed communities of algal symbionts in reef corals." Molecular Ecology, v.25, 2016, p.2724.

EK Towle, AM Palacio-Castro, AC Baker, C Langdon "Source location and food availability determine the growth response of Orbicella faveolata to climate change stressors." Regional Studies in Marine Science, v.10, 2017, p.107.

Cunning R, Bay RA, Gillette P, Baker AC, Traylor-Knowles N "Comparative analysis of the Pocillopora damicornis genome highlights role of immune system in coral evolution." Scientific Reports, v.8, 2018, p.16134.

Chaput R, Paris CB, Smith SG, Baker AC "Reef fish larvae visually discriminate coral diversity during settlement." Bulletin of Marine Science., v., 2019, p.. doi:10.5343/bms.2018.0063 

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.

Reef-building corals are symbioses between animals and photosynthetic algae. These partnerships can break down due to high-temperature stress in a process called coral "bleaching", which is now threatening reefs worldwide due to climate change. This project developed and tested a new genetic technique to assess the symbiotic status of corals in an effort to help understand if (and why) corals become more susceptible to heat-induced bleaching in certain environmental conditions. Specifically, this project tested the hypothesis that changes in the ratio of algal symbiont cells to coral host cells affect the thermal tolerance of reef-building corals, with corals that have higher ratios (too many symbionts) being more susceptible to bleaching. The project: (1) established a program in the Florida Keys to monitor changes in symbiont:host cell ratios in the field, how they vary between species, and how they respond to seasonal changes; and (2) used laboratory experiments to test whether corals raised under different environmental conditions (including elevated nutrients and carbon dioxide) increase their symbiont:host cell ratios and become more thermally sensitive as a result. These investigations showed that the symbiont:host cell ratio was a cost-effective way of rapidly obtaining quantitative information on both the abundance and identity of different algal symbionts from just a tiny DNA sample. More importantly, symbiont:host cell ratios are a useful indicator of the "symbiotic health" of corals and (although they are subject to considerable variability across species and can be severely disrupted in the event of bleaching) represent a useful way of monitoring symbiont changes in corals over time. This approach has now become a standard tool in our lab and is beginning to be adopted by other labs. During the course of this award we also expanded the use of the technique into the study of how corals could be manipulated to contain different algal symbionts in order to increase their thermal tolerance, which has some implications for how scientists might be able to increase the thermal tolerance of corals by manipulating their algal symbiont communities. These elements of the project led to the PI serving on a National Academy of Sciences committee at the end of the award (2018-19) to review interventions to increase the persistence and resilience of coral reefs, and guide managers in how they might be employed. This project contributed to the training of one postdoctoral scientist, four PhD students, and four Master's students, and provided research experience to 13 undergraduates. The research being done in the laboratory was also featured in mass media, such as shows like Netflix's "Liquid Science", and the BBC's science and technology show "Click", in which the PI discussed the threats facing coral reefs and how research on coral-algal symbiosis might help coral reefs survive the coming decades.

Last Modified: 08/02/2019
Modified by: Andrew C Baker

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