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Alderdice R, Perna G, Cárdenas A, Hume BCC, Wolf M, Kühl M, Pernice M, Suggett DJ, Voolstra CR. Author Correction: Deoxygenation lowers the thermal threshold of coral bleaching. Sci Rep 2023; 13:13254. [PMID: 37582837 PMCID: PMC10427604 DOI: 10.1038/s41598-023-40318-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/17/2023] Open
Affiliation(s)
- Rachel Alderdice
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia.
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany.
| | - Gabriela Perna
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Anny Cárdenas
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Benjamin C C Hume
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Martin Wolf
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Michael Kühl
- Marine Biology Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000, Helsingør, Denmark
| | - Mathieu Pernice
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - David J Suggett
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
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Alderdice R, Perna G, Cárdenas A, Hume BCC, Wolf M, Kühl M, Pernice M, Suggett DJ, Voolstra CR. Deoxygenation lowers the thermal threshold of coral bleaching. Sci Rep 2022; 12:18273. [PMID: 36316371 PMCID: PMC9622859 DOI: 10.1038/s41598-022-22604-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/17/2022] [Indexed: 12/02/2022] Open
Abstract
Exposure to deoxygenation from climate warming and pollution is emerging as a contributing factor of coral bleaching and mortality. However, the combined effects of heating and deoxygenation on bleaching susceptibility remain unknown. Here, we employed short-term thermal stress assays to show that deoxygenated seawater can lower the thermal limit of an Acropora coral by as much as 1 °C or 0.4 °C based on bleaching index scores or dark-acclimated photosynthetic efficiencies, respectively. Using RNA-Seq, we show similar stress responses to heat with and without deoxygenated seawater, both activating putative key genes of the hypoxia-inducible factor response system indicative of cellular hypoxia. We also detect distinct deoxygenation responses, including a disruption of O2-dependent photo-reception/-protection, redox status, and activation of an immune response prior to the onset of bleaching. Thus, corals are even more vulnerable when faced with heat stress in deoxygenated waters. This highlights the need to integrate dissolved O2 measurements into global monitoring programs of coral reefs.
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Affiliation(s)
- Rachel Alderdice
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia.
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany.
| | - Gabriela Perna
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Anny Cárdenas
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Benjamin C C Hume
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Martin Wolf
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Michael Kühl
- Marine Biology Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000, Helsingør, Denmark
| | - Mathieu Pernice
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - David J Suggett
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
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Alderdice R, Pernice M, Cárdenas A, Hughes DJ, Harrison PL, Boulotte N, Chartrand K, Kühl M, Suggett DJ, Voolstra CR. Hypoxia as a physiological cue and pathological stress for coral larvae. Mol Ecol 2021; 31:571-587. [PMID: 34716959 DOI: 10.1111/mec.16259] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 10/15/2021] [Accepted: 10/20/2021] [Indexed: 11/30/2022]
Abstract
Ocean deoxygenation events are intensifying worldwide and can rapidly drive adult corals into a state of metabolic crisis and bleaching-induced mortality, but whether coral larvae are subject to similar stress remains untested. We experimentally exposed apo-symbiotic coral larvae of Acropora selago to deoxygenation stress with subsequent reoxygenation aligned to their night-day light cycle, and followed their gene expression using RNA-Seq. After 12 h of deoxygenation stress (~2 mg O2 /L), coral planulae demonstrated a low expression of HIF-targeted hypoxia response genes concomitant with a significantly high expression of PHD2 (a promoter of HIFα proteasomal degradation), similar to corresponding adult corals. Despite exhibiting a consistent swimming phenotype compared to control samples, the differential gene expression observed in planulae exposed to deoxygenation-reoxygenation suggests a disruption of pathways involved in developmental regulation, mitochondrial activity, lipid metabolism, and O2 -sensitive epigenetic regulators. Importantly, we found that treated larvae exhibited a disruption in the expression of conserved HIF-targeted developmental regulators, for example, Homeobox (HOX) genes, corroborating how changes in external oxygen levels can affect animal development. We discuss how the observed deoxygenation responses may be indicative of a possible acclimation response or alternatively may imply negative latent impacts for coral larval fitness.
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Affiliation(s)
- Rachel Alderdice
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, NSW, Australia
| | - Mathieu Pernice
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, NSW, Australia
| | - Anny Cárdenas
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - David J Hughes
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, NSW, Australia
| | - Peter L Harrison
- Marine Ecology Research Centre, Southern Cross University, Lismore, NSW, Australia
| | - Nadine Boulotte
- Marine Ecology Research Centre, Southern Cross University, Lismore, NSW, Australia
| | - Katie Chartrand
- Centre of Tropical Water and Aquatic Ecosystem Research, James Cook University, Townsville, Qld, Australia
| | - Michael Kühl
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, NSW, Australia.,Marine Biology Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - David J Suggett
- Faculty of Science, Climate Change Cluster, University of Technology Sydney, Ultimo, NSW, Australia
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Alderdice R, Suggett DJ, Cárdenas A, Hughes DJ, Kühl M, Pernice M, Voolstra CR. Divergent expression of hypoxia response systems under deoxygenation in reef-forming corals aligns with bleaching susceptibility. Glob Chang Biol 2021; 27:312-326. [PMID: 33197302 DOI: 10.1111/gcb.15436] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 10/27/2020] [Indexed: 06/11/2023]
Abstract
Exposure of marine life to low oxygen is accelerating worldwide via climate change and localized pollution. Mass coral bleaching and mortality have recently occurred where reefs have experienced chronic low oxygen events. However, the mechanistic basis of tolerance to oxygen levels inadequate to sustain normal functioning (i.e. hypoxia) and whether it contributes to bleaching susceptibility, remain unknown. We therefore experimentally exposed colonies of the environmentally resilient Acropora tenuis, a common reef-building coral from the Great Barrier Reef, to deoxygenation-reoxygenation stress that was aligned to their natural night-day light cycle. Specifically, the treatment involved removing the 'night-time O2 buffer' to challenge the inherent hypoxia thresholds. RNA-Seq analysis revealed that coral possess a complete and active hypoxia-inducible factor (HIF)-mediated hypoxia response system (HRS) homologous to other metazoans. As expected, A. tenuis exhibited bleaching resistance and showed a strong inducibility of HIF target genes in response to deoxygenation stress. We applied this same approach in parallel to a colony of Acropora selago, known to be environmnetally susceptible, which conversely exhibited a bleaching phenotype response. This phenotypic divergence of A. selago was accompanied by contrasting gene expression profiles indicative of varied effectiveness of their HIF-HRS. Based on our RNA-Seq analysis, we propose (a) that the HIF-HRS is central for corals to manage deoxygenation stress and (b) that key genes of this system (and the wider gene network) may contribute to variation in coral bleaching susceptibility. Our analysis suggests that heat shock protein (hsp) 70 and 90 are important for low oxygen stress tolerance and further highlights how hsp90 expression might also affect the inducibility of coral HIF-HRS in overcoming a metabolic crisis under deoxygenation stress. We propose that differences in coral HIF-HRS could be central in regulating sensitivity to other climate change stressors-notably thermal stress-that commonly drive bleaching.
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Affiliation(s)
- Rachel Alderdice
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - David J Suggett
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - Anny Cárdenas
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - David J Hughes
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - Michael Kühl
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
- Marine Biology Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Mathieu Pernice
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
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Bollati E, D'Angelo C, Alderdice R, Pratchett M, Ziegler M, Wiedenmann J. Optical Feedback Loop Involving Dinoflagellate Symbiont and Scleractinian Host Drives Colorful Coral Bleaching. Curr Biol 2020; 30:2433-2445.e3. [PMID: 32442463 DOI: 10.1016/j.cub.2020.04.055] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 02/19/2020] [Accepted: 04/21/2020] [Indexed: 11/25/2022]
Abstract
Coral bleaching, caused by the loss of brownish-colored dinoflagellate photosymbionts from the host tissue of reef-building corals, is a major threat to reef survival. Occasionally, bleached corals become exceptionally colorful rather than white. These colors derive from photoprotective green fluorescent protein (GFP)-like pigments produced by the coral host. There is currently no consensus regarding what causes colorful bleaching events and what the consequences for the corals are. Here, we document that colorful bleaching events are a recurring phenomenon in reef regions around the globe. Our analysis of temperature conditions associated with colorful bleaching events suggests that corals develop extreme coloration within 2 to 3 weeks after exposure to mild or temporary heat stress. We demonstrate that the increase of light fluxes in symbiont-depleted tissue promoted by reflection of the incident light from the coral skeleton induces strong expression of the photoprotective coral host pigments. We describe an optical feedback loop involving both partners of the association, discussing that the mitigation of light stress offered by host pigments could facilitate recolonization of bleached tissue by symbionts. Our data indicate that colorful bleaching has the potential to identify local environmental factors, such as nutrient stress, that can exacerbate the impact of elevated temperatures on corals, to indicate the severity of heat stress experienced by corals and to gauge their post-stress recovery potential. VIDEO ABSTRACT.
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Affiliation(s)
- Elena Bollati
- Coral Reef Laboratory, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK; Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore
| | - Cecilia D'Angelo
- Coral Reef Laboratory, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK; Institute for Life Sciences (IFLS), University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK
| | - Rachel Alderdice
- Coral Reef Laboratory, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK; Climate Change Cluster, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Morgan Pratchett
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
| | - Maren Ziegler
- Systematics & Biodiversity Lab, Justus Liebig University, 35392 Giessen, Germany; Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Jörg Wiedenmann
- Coral Reef Laboratory, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK; Institute for Life Sciences (IFLS), University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK.
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