Empirically derived thermal thresholds of four coral species along the Red Sea using a portable and standardized experimental approach

Nicolas R. Evensen; Christian R. Voolstra; Maoz Fine; Gabriela Perna; Carol Buitrago-López; Anny Cárdenas; Guilhem Banc-Prandi; Katherine Rowe; Daniel J. Barshis

doi:10.1007/s00338-022-02233-y

Empirically derived thermal thresholds of four coral species along the Red Sea using a portable and standardized experimental approach

Nicolas R. Evensen^*, Christian R. Voolstra^*, Maoz Fine, Gabriela Perna, Carol Buitrago-López, Anny Cárdenas, Guilhem Banc-Prandi, Katherine Rowe, Daniel J. Barshis^*

^*Corresponding author for this work

Department of Ecology, Evolution & Behavior (EEB)

Research output: Contribution to journal › Article › peer-review

14 Scopus citations

Abstract

Global warming is causing an unprecedented loss of species and habitats worldwide. This is particularly apparent for tropical coral reefs, with an increasing number of reefs experiencing mass bleaching and mortality on an annual basis. As such, there is a growing need for a standardized experimental approach to rapidly assess the thermal limits of corals and predict the survival of coral species across reefs and regions. Using a portable experimental system, the Coral Bleaching Automated Stress System (CBASS), we conducted standardized 18 h acute thermal stress assays to quantitively determine the upper thermal limits of four coral species across the length of the Red Sea coastline, from the Gulf of Aqaba (GoA) to Djibouti (~ 2100 km). We measured dark-acclimated photosynthetic efficiency (F_v/F_m), algal symbiont density, chlorophyll a, and visual bleaching intensity following heat stress. F_v/F_m was the most precise response variable assessed, advancing the F_v/F_m effective dose 50 (ED50, i.e., the temperature at which 50% of the initial F_v/F_m is measured) as an empirically derived proxy for thermal tolerance. ED50 thermal thresholds from the central/southern Red Sea and Djibouti populations were consistently higher for Acropora hemprichii, Pocillopora verrucosa, and Stylophora pistillata (0.1–1.8 °C above GoA corals, respectively), in line with prevailing warmer maximum monthly means (MMMs), though were lower than GoA corals relative to site MMMs (1.5–3.0 °C). P. verrucosa had the lowest thresholds overall. Despite coming from the hottest site, thresholds were lowest for Porites lobata in the southern Red Sea, suggesting long-term physiological damage or ongoing recovery from a severe, prior bleaching event. Altogether, the CBASS resolved historical, taxonomic, and possibly recent environmental drivers of variation in coral thermal thresholds, highlighting the potential for a standardized, short-term thermal assay as a universal approach for assessing ecological and evolutionary variation in the upper thermal limits of corals.

Original language	American English
Pages (from-to)	239-252
Number of pages	14
Journal	Coral Reefs
Volume	41
Issue number	2
DOIs	https://doi.org/10.1007/s00338-022-02233-y
State	Published - Apr 2022

Bibliographical note

Funding Information:
We thank Jessica Bellworthy, Dror Komet, and all the skippers and boat crews for their invaluable help and support, as well as the reviewers for providing valuable feedback that improved the manuscript. We also thank the Direction de l'Environnement et de Développement Durable (DEDD) and Ministry of the Environment and Sustainable Development (MEDD) for their critical assistance in supporting the research in Djibouti, particularly Mme Bilan Hassan Ismail and Dr. Youssouf Moussa Omar, through coordination of the research, permits, and sample transport, as well as Chris Canellakis and Omar Awaleh from the US Embassy for their logistical support. This research was supported by funding from the U.S. Israeli Binational Science foundation (award 2016403 to DJB and MF), National Science Foundation (award 1833201 to DJB), and by the University of Konstanz and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project number 433042944 (to CRV). On behalf of all authors, the corresponding authors state that there is no conflict of interest.

Funding Information:
We thank Jessica Bellworthy, Dror Komet, and all the skippers and boat crews for their invaluable help and support, as well as the reviewers for providing valuable feedback that improved the manuscript. We also thank the Direction de l'Environnement et de D?veloppement Durable (DEDD) and Ministry of the Environment and Sustainable Development (MEDD) for their critical assistance in supporting the research in Djibouti, particularly Mme Bilan Hassan Ismail?and Dr.?Youssouf Moussa Omar, through coordination of the research, permits, and sample transport, as well as Chris Canellakis and Omar Awaleh from the US Embassy for their logistical support. This research was supported by funding from the U.S. Israeli Binational Science foundation (award 2016403 to DJB and MF), National Science Foundation (award 1833201 to DJB), and by the University of Konstanz and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project number 433042944 (to CRV). On behalf of all authors, the corresponding authors state that there is no conflict of interest.

Publisher Copyright:
© 2022, The Author(s).

Keywords

Coral Bleaching Automated Stress System (CBASS)
Coral thermotolerance
Ocean warming
Red Sea
Standardized acute assays
Thermal stress

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1007/s00338-022-02233-y

Cite this

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title = "Empirically derived thermal thresholds of four coral species along the Red Sea using a portable and standardized experimental approach",

abstract = "Global warming is causing an unprecedented loss of species and habitats worldwide. This is particularly apparent for tropical coral reefs, with an increasing number of reefs experiencing mass bleaching and mortality on an annual basis. As such, there is a growing need for a standardized experimental approach to rapidly assess the thermal limits of corals and predict the survival of coral species across reefs and regions. Using a portable experimental system, the Coral Bleaching Automated Stress System (CBASS), we conducted standardized 18 h acute thermal stress assays to quantitively determine the upper thermal limits of four coral species across the length of the Red Sea coastline, from the Gulf of Aqaba (GoA) to Djibouti (~ 2100 km). We measured dark-acclimated photosynthetic efficiency (Fv/Fm), algal symbiont density, chlorophyll a, and visual bleaching intensity following heat stress. Fv/Fm was the most precise response variable assessed, advancing the Fv/Fm effective dose 50 (ED50, i.e., the temperature at which 50% of the initial Fv/Fm is measured) as an empirically derived proxy for thermal tolerance. ED50 thermal thresholds from the central/southern Red Sea and Djibouti populations were consistently higher for Acropora hemprichii, Pocillopora verrucosa, and Stylophora pistillata (0.1–1.8 °C above GoA corals, respectively), in line with prevailing warmer maximum monthly means (MMMs), though were lower than GoA corals relative to site MMMs (1.5–3.0 °C). P. verrucosa had the lowest thresholds overall. Despite coming from the hottest site, thresholds were lowest for Porites lobata in the southern Red Sea, suggesting long-term physiological damage or ongoing recovery from a severe, prior bleaching event. Altogether, the CBASS resolved historical, taxonomic, and possibly recent environmental drivers of variation in coral thermal thresholds, highlighting the potential for a standardized, short-term thermal assay as a universal approach for assessing ecological and evolutionary variation in the upper thermal limits of corals.",

keywords = "Coral Bleaching Automated Stress System (CBASS), Coral thermotolerance, Ocean warming, Red Sea, Standardized acute assays, Thermal stress",

author = "Evensen, {Nicolas R.} and Voolstra, {Christian R.} and Maoz Fine and Gabriela Perna and Carol Buitrago-L{\'o}pez and Anny C{\'a}rdenas and Guilhem Banc-Prandi and Katherine Rowe and Barshis, {Daniel J.}",

note = "Funding Information: We thank Jessica Bellworthy, Dror Komet, and all the skippers and boat crews for their invaluable help and support, as well as the reviewers for providing valuable feedback that improved the manuscript. We also thank the Direction de l'Environnement et de D{\'e}veloppement Durable (DEDD) and Ministry of the Environment and Sustainable Development (MEDD) for their critical assistance in supporting the research in Djibouti, particularly Mme Bilan Hassan Ismail and Dr. Youssouf Moussa Omar, through coordination of the research, permits, and sample transport, as well as Chris Canellakis and Omar Awaleh from the US Embassy for their logistical support. This research was supported by funding from the U.S. Israeli Binational Science foundation (award 2016403 to DJB and MF), National Science Foundation (award 1833201 to DJB), and by the University of Konstanz and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project number 433042944 (to CRV). On behalf of all authors, the corresponding authors state that there is no conflict of interest. Funding Information: We thank Jessica Bellworthy, Dror Komet, and all the skippers and boat crews for their invaluable help and support, as well as the reviewers for providing valuable feedback that improved the manuscript. We also thank the Direction de l'Environnement et de D?veloppement Durable (DEDD) and Ministry of the Environment and Sustainable Development (MEDD) for their critical assistance in supporting the research in Djibouti, particularly Mme Bilan Hassan Ismail?and Dr.?Youssouf Moussa Omar, through coordination of the research, permits, and sample transport, as well as Chris Canellakis and Omar Awaleh from the US Embassy for their logistical support. This research was supported by funding from the U.S. Israeli Binational Science foundation (award 2016403 to DJB and MF), National Science Foundation (award 1833201 to DJB), and by the University of Konstanz and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project number 433042944 (to CRV). On behalf of all authors, the corresponding authors state that there is no conflict of interest. Publisher Copyright: {\textcopyright} 2022, The Author(s).",

year = "2022",

month = apr,

doi = "10.1007/s00338-022-02233-y",

language = "American English",

volume = "41",

pages = "239--252",

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T1 - Empirically derived thermal thresholds of four coral species along the Red Sea using a portable and standardized experimental approach

AU - Evensen, Nicolas R.

AU - Voolstra, Christian R.

AU - Fine, Maoz

AU - Perna, Gabriela

AU - Buitrago-López, Carol

AU - Cárdenas, Anny

AU - Banc-Prandi, Guilhem

AU - Rowe, Katherine

AU - Barshis, Daniel J.

N1 - Funding Information: We thank Jessica Bellworthy, Dror Komet, and all the skippers and boat crews for their invaluable help and support, as well as the reviewers for providing valuable feedback that improved the manuscript. We also thank the Direction de l'Environnement et de Développement Durable (DEDD) and Ministry of the Environment and Sustainable Development (MEDD) for their critical assistance in supporting the research in Djibouti, particularly Mme Bilan Hassan Ismail and Dr. Youssouf Moussa Omar, through coordination of the research, permits, and sample transport, as well as Chris Canellakis and Omar Awaleh from the US Embassy for their logistical support. This research was supported by funding from the U.S. Israeli Binational Science foundation (award 2016403 to DJB and MF), National Science Foundation (award 1833201 to DJB), and by the University of Konstanz and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project number 433042944 (to CRV). On behalf of all authors, the corresponding authors state that there is no conflict of interest. Funding Information: We thank Jessica Bellworthy, Dror Komet, and all the skippers and boat crews for their invaluable help and support, as well as the reviewers for providing valuable feedback that improved the manuscript. We also thank the Direction de l'Environnement et de D?veloppement Durable (DEDD) and Ministry of the Environment and Sustainable Development (MEDD) for their critical assistance in supporting the research in Djibouti, particularly Mme Bilan Hassan Ismail?and Dr.?Youssouf Moussa Omar, through coordination of the research, permits, and sample transport, as well as Chris Canellakis and Omar Awaleh from the US Embassy for their logistical support. This research was supported by funding from the U.S. Israeli Binational Science foundation (award 2016403 to DJB and MF), National Science Foundation (award 1833201 to DJB), and by the University of Konstanz and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) project number 433042944 (to CRV). On behalf of all authors, the corresponding authors state that there is no conflict of interest. Publisher Copyright: © 2022, The Author(s).

PY - 2022/4

Y1 - 2022/4

N2 - Global warming is causing an unprecedented loss of species and habitats worldwide. This is particularly apparent for tropical coral reefs, with an increasing number of reefs experiencing mass bleaching and mortality on an annual basis. As such, there is a growing need for a standardized experimental approach to rapidly assess the thermal limits of corals and predict the survival of coral species across reefs and regions. Using a portable experimental system, the Coral Bleaching Automated Stress System (CBASS), we conducted standardized 18 h acute thermal stress assays to quantitively determine the upper thermal limits of four coral species across the length of the Red Sea coastline, from the Gulf of Aqaba (GoA) to Djibouti (~ 2100 km). We measured dark-acclimated photosynthetic efficiency (Fv/Fm), algal symbiont density, chlorophyll a, and visual bleaching intensity following heat stress. Fv/Fm was the most precise response variable assessed, advancing the Fv/Fm effective dose 50 (ED50, i.e., the temperature at which 50% of the initial Fv/Fm is measured) as an empirically derived proxy for thermal tolerance. ED50 thermal thresholds from the central/southern Red Sea and Djibouti populations were consistently higher for Acropora hemprichii, Pocillopora verrucosa, and Stylophora pistillata (0.1–1.8 °C above GoA corals, respectively), in line with prevailing warmer maximum monthly means (MMMs), though were lower than GoA corals relative to site MMMs (1.5–3.0 °C). P. verrucosa had the lowest thresholds overall. Despite coming from the hottest site, thresholds were lowest for Porites lobata in the southern Red Sea, suggesting long-term physiological damage or ongoing recovery from a severe, prior bleaching event. Altogether, the CBASS resolved historical, taxonomic, and possibly recent environmental drivers of variation in coral thermal thresholds, highlighting the potential for a standardized, short-term thermal assay as a universal approach for assessing ecological and evolutionary variation in the upper thermal limits of corals.

AB - Global warming is causing an unprecedented loss of species and habitats worldwide. This is particularly apparent for tropical coral reefs, with an increasing number of reefs experiencing mass bleaching and mortality on an annual basis. As such, there is a growing need for a standardized experimental approach to rapidly assess the thermal limits of corals and predict the survival of coral species across reefs and regions. Using a portable experimental system, the Coral Bleaching Automated Stress System (CBASS), we conducted standardized 18 h acute thermal stress assays to quantitively determine the upper thermal limits of four coral species across the length of the Red Sea coastline, from the Gulf of Aqaba (GoA) to Djibouti (~ 2100 km). We measured dark-acclimated photosynthetic efficiency (Fv/Fm), algal symbiont density, chlorophyll a, and visual bleaching intensity following heat stress. Fv/Fm was the most precise response variable assessed, advancing the Fv/Fm effective dose 50 (ED50, i.e., the temperature at which 50% of the initial Fv/Fm is measured) as an empirically derived proxy for thermal tolerance. ED50 thermal thresholds from the central/southern Red Sea and Djibouti populations were consistently higher for Acropora hemprichii, Pocillopora verrucosa, and Stylophora pistillata (0.1–1.8 °C above GoA corals, respectively), in line with prevailing warmer maximum monthly means (MMMs), though were lower than GoA corals relative to site MMMs (1.5–3.0 °C). P. verrucosa had the lowest thresholds overall. Despite coming from the hottest site, thresholds were lowest for Porites lobata in the southern Red Sea, suggesting long-term physiological damage or ongoing recovery from a severe, prior bleaching event. Altogether, the CBASS resolved historical, taxonomic, and possibly recent environmental drivers of variation in coral thermal thresholds, highlighting the potential for a standardized, short-term thermal assay as a universal approach for assessing ecological and evolutionary variation in the upper thermal limits of corals.

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Empirically derived thermal thresholds of four coral species along the Red Sea using a portable and standardized experimental approach

Abstract

Bibliographical note

Keywords

UN SDGs

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