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Qin B, Yu K, Fu Y, Zhou Y, Wu Y, Zhang W, Chen X. Responses in reef-building corals to wildfire emissions: Heterotrophic plasticity and calcification. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 922:171271. [PMID: 38428592 DOI: 10.1016/j.scitotenv.2024.171271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 02/04/2024] [Accepted: 02/23/2024] [Indexed: 03/03/2024]
Abstract
Extreme wildfire events are on the rise globally, and although substantial wildfire emissions may find their way into the ocean, their impact on coral reefs remains uncertain. In a five-week laboratory experiment, we observed a significant reduction in photosynthesis in coral symbionts (Porites lutea) when exposed to fine particulate matter (PM2.5) from wildfires. At low PM2.5 level (2 mg L-1), the changes in δ13C and δ15N values in the host and symbiotic algae suggest reduced autotrophy and the utilization of wildfire particulates as a source of heterotrophic nutrients. This adaptive strategy, characterized by an increase in heterotrophy, sustained some aspects of coral growth (total biomass, proteins and lipids) under wildfire stress. Nevertheless, at high PM2.5 level (5 mg L-1), both autotrophy and heterotrophy significantly decreased, resulting in an imbalanced coral-algal nutritional relationship. These changes were related to light attenuation in seawater and particulate accumulation on the coral surface during PM2.5 deposition, ultimately rendering the coral growth unsustainable. Further, the calcification rates decreased by 1.5 to 1.85 times under both low and high levels of PM2.5, primarily affected by photosynthetic autotrophy rather than heterotrophy. Our study highlights a constrained heterotrophic plasticity of corals under wildfire stress. This limitation may restrict wildfire emissions as an alternative nutrient source to support coral growth and calcification, especially when oceanic food availability or autotrophy declines, as seen during bleaching induced by the warming ocean.
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Affiliation(s)
- Bo Qin
- Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Coral Reef Research Center of China, School of Marine Sciences, Guangxi University, Nanning 530004, China; School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China
| | - Kefu Yu
- Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Coral Reef Research Center of China, School of Marine Sciences, Guangxi University, Nanning 530004, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China.
| | - Yichen Fu
- Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Coral Reef Research Center of China, School of Marine Sciences, Guangxi University, Nanning 530004, China
| | - Yu Zhou
- Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Coral Reef Research Center of China, School of Marine Sciences, Guangxi University, Nanning 530004, China
| | - Yanliu Wu
- Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Coral Reef Research Center of China, School of Marine Sciences, Guangxi University, Nanning 530004, China
| | - Wenqian Zhang
- Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Coral Reef Research Center of China, School of Marine Sciences, Guangxi University, Nanning 530004, China
| | - Xiaoyan Chen
- Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Coral Reef Research Center of China, School of Marine Sciences, Guangxi University, Nanning 530004, China.
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Krämer WE, Iglesias-Prieto R, Enríquez S. Evaluation of the current understanding of the impact of climate change on coral physiology after three decades of experimental research. Commun Biol 2022; 5:1418. [PMID: 36572721 PMCID: PMC9792581 DOI: 10.1038/s42003-022-04353-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 12/08/2022] [Indexed: 12/27/2022] Open
Abstract
After three decades of coral research on the impacts of climate change, there is a wide consensus on the adverse effects of heat-stress, but the impacts of ocean acidification (OA) are not well established. Using a review of published studies and an experimental analysis, we confirm the large species-specific component of the OA response, which predicts moderate impacts on coral physiology and pigmentation by 2100 (scenario-B1 or SSP2-4.5), in contrast with the severe disturbances induced by only +2 °C of thermal anomaly. Accordingly, global warming represents a greater threat for coral calcification than OA. The incomplete understanding of the moderate OA response relies on insufficient attention to key regulatory processes of these symbioses, particularly the metabolic dependence of coral calcification on algal photosynthesis and host respiration. Our capacity to predict the future of coral reefs depends on a correct identification of the main targets and/or processes impacted by climate change stressors.
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Affiliation(s)
- Wiebke E. Krämer
- grid.9486.30000 0001 2159 0001Laboratory of Photobiology, Unidad Académica de Sistemas Arrecifales (Puerto Morelos), Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Quintana Roo Cancún, Mexico
| | - Roberto Iglesias-Prieto
- grid.9486.30000 0001 2159 0001Laboratory of Photobiology, Unidad Académica de Sistemas Arrecifales (Puerto Morelos), Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Quintana Roo Cancún, Mexico ,grid.29857.310000 0001 2097 4281Present Address: Department of Biology, The Pennsylvania State University, University Park, PA 16802 USA
| | - Susana Enríquez
- grid.9486.30000 0001 2159 0001Laboratory of Photobiology, Unidad Académica de Sistemas Arrecifales (Puerto Morelos), Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Quintana Roo Cancún, Mexico
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3
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In vivo assessment of mitochondrial respiratory alternative oxidase activity and cyclic electron flow around photosystem I on small coral fragments. Sci Rep 2020; 10:17514. [PMID: 33060749 PMCID: PMC7562913 DOI: 10.1038/s41598-020-74557-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 10/05/2020] [Indexed: 12/31/2022] Open
Abstract
The mutualistic relationship existing between scleractinian corals and their photosynthetic endosymbionts involves a complex integration of the metabolic pathways within the holobiont. Respiration and photosynthesis are the most important of these processes and although they have been extensively studied, our understanding of their interactions and regulatory mechanisms is still limited. In this work we performed chlorophyll-a fluorescence, oxygen exchange and time-resolved absorption spectroscopy measurements on small and thin fragments (0.3 cm2) of the coral Stylophora pistillata. We showed that the capacity of mitochondrial alternative oxidase accounted for ca. 25% of total coral respiration, and that the high-light dependent oxygen uptake, commonly present in isolated Symbiodiniaceae, was negligible. The ratio between photosystem I (PSI) and photosystem II (PSII) active centers as well as their respective electron transport rates, indicated that PSI cyclic electron flow occurred in high light in S. pistillata and in some branching and lamellar coral species freshly collected in the field. Altogether, these results show the potential of applying advanced biophysical and spectroscopic methods on small coral fragments to understand the complex mechanisms of coral photosynthesis and respiration and their responses to environmental changes.
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Bernardet C, Tambutté E, Techer N, Tambutté S, Venn AA. Ion transporter gene expression is linked to the thermal sensitivity of calcification in the reef coral Stylophora pistillata. Sci Rep 2019; 9:18676. [PMID: 31822787 PMCID: PMC6904480 DOI: 10.1038/s41598-019-54814-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 10/21/2019] [Indexed: 12/22/2022] Open
Abstract
Coral calcification underpins biodiverse reef ecosystems, but the physiology underlying the thermal sensitivity of corals to changing seawater temperatures remains unclear. Furthermore, light is also a key factor in modulating calcification rates, but a mechanistic understanding of how light interacts with temperature to affect coral calcification is lacking. Here, we characterized the thermal performance curve (TPC) of calcification of the wide-spread, model coral species Stylophora pistillata, and used gene expression analysis to investigate the role of ion transport mechanisms in thermally-driven declines in day and nighttime calcification. Focusing on genes linked to transport of dissolved inorganic carbon (DIC), calcium and H+, our study reveals a high degree of coherence between physiological responses (e.g. calcification and respiration) with distinct gene expression patterns to the different temperatures in day and night conditions. At low temperatures, calcification and gene expression linked to DIC transport processes were downregulated, but showed little response to light. By contrast, at elevated temperature, light had a positive effect on calcification and stimulated a more functionally diverse gene expression response of ion transporters. Overall, our findings highlight the role of mechanisms linked to DIC, calcium and H+ transport in the thermal sensitivity of coral calcification and how this sensitivity is influenced by light.
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Affiliation(s)
- C Bernardet
- Centre Scientifique de Monaco, Marine Biology Department, 8 Quai Antoine 1er, Monaco, 98000, Monaco
- Sorbonne Université, Collège Doctoral, F-75005, Paris, France
| | - E Tambutté
- Centre Scientifique de Monaco, Marine Biology Department, 8 Quai Antoine 1er, Monaco, 98000, Monaco
| | | | - S Tambutté
- Centre Scientifique de Monaco, Marine Biology Department, 8 Quai Antoine 1er, Monaco, 98000, Monaco
| | - A A Venn
- Centre Scientifique de Monaco, Marine Biology Department, 8 Quai Antoine 1er, Monaco, 98000, Monaco.
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Taubner I, Hu MY, Eisenhauer A, Bleich M. Electrophysiological evidence for light-activated cation transport in calcifying corals. Proc Biol Sci 2019; 286:20182444. [PMID: 30963934 PMCID: PMC6408601 DOI: 10.1098/rspb.2018.2444] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/23/2019] [Indexed: 12/17/2022] Open
Abstract
Light has been demonstrated to enhance calcification rates in hermatypic coral species. To date, it remains unresolved whether calcifying epithelia change their ion transport activity during illumination, and whether such a process is mediated by the endosymbiotic algae or can be controlled by the coral host itself. Using a modified Ussing chamber in combination with H+ sensitive microelectrode measurements, the present work demonstrates that light triggers the generation of a skeleton positive potential of up to 0.9 mV in the hermatypic coral Stylophora pistillata. This potential is generated by a net flux of cations towards the skeleton and reaches its maximum at blue (450 nm) light. The effects of pharmacological inhibitors targeting photosynthesis 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and anion transport 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) were investigated by pH microelectrode measurements in coral tissues demonstrating a rapid decrease in tissue pH under illumination. However, these inhibitors showed no effect on the electrophysiological light response of the coral host. By contrast, metabolic inhibition by cyanide and deoxyglucose reversibly inhibited the light-induced cation flux towards the skeleton. These results suggest that ion transport across coral epithelia is directly triggered by blue light, independent of photosynthetic activity of algal endosymbionts. Measurements of this very specific and quantifiable physiological response can provide parameters to identify photoreception mechanisms and will help to broaden our understanding of the mechanistic link between light stimulation and epithelial ion transport, potentially relevant for calcification in hermatypic corals.
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Affiliation(s)
- Isabelle Taubner
- Christian-Albrechts-Universität, Institute of Physiology, Kiel, Germany
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Marian Y. Hu
- Christian-Albrechts-Universität, Institute of Physiology, Kiel, Germany
| | | | - Markus Bleich
- Christian-Albrechts-Universität, Institute of Physiology, Kiel, Germany
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Hawkins TD, Warner ME. Warm preconditioning protects against acute heat-induced respiratory dysfunction and delays bleaching in a symbiotic sea anemone. ACTA ACUST UNITED AC 2016; 220:969-983. [PMID: 27980125 DOI: 10.1242/jeb.150391] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 12/08/2016] [Indexed: 12/18/2022]
Abstract
Preconditioning to non-stressful warming can protect some symbiotic cnidarians against the high temperature-induced collapse of their mutualistic endosymbiosis with photosynthetic dinoflagellates (Symbiodinium spp.), a process known as bleaching. Here, we sought to determine whether such preconditioning is underpinned by differential regulation of aerobic respiration. We quantified in vivo metabolism and mitochondrial respiratory enzyme activity in the naturally symbiotic sea anemone Exaiptasia pallida preconditioned to 30°C for >7 weeks as well as anemones kept at 26°C. Preconditioning resulted in increased Symbiodinium photosynthetic activity and holobiont (host+symbiont) respiration rates. Biomass-normalised activities of host respiratory enzymes [citrate synthase and the mitochondrial electron transport chain (mETC) complexes I and IV] were higher in preconditioned animals, suggesting that increased holobiont respiration may have been due to host mitochondrial biogenesis and/or enlargement. Subsequent acute heating of preconditioned and 'thermally naive' animals to 33°C induced dramatic increases in host mETC complex I and Symbiodinium mETC complex II activities only in thermally naive E. pallida These changes were not reflected in the activities of other respiratory enzymes. Furthermore, bleaching in preconditioned E. pallida (defined as the significant loss of symbionts) was delayed by several days relative to the thermally naive group. These findings suggest that changes to mitochondrial biogenesis and/or function in symbiotic cnidarians during warm preconditioning might play a protective role during periods of exposure to stressful heating.
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Affiliation(s)
- Thomas D Hawkins
- School of Marine Science and Policy, College of Earth, Ocean and Environment, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA
| | - Mark E Warner
- School of Marine Science and Policy, College of Earth, Ocean and Environment, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA
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Bertucci A, Forêt S, Ball EE, Miller DJ. Transcriptomic differences between day and night in Acropora millepora provide new insights into metabolite exchange and light-enhanced calcification in corals. Mol Ecol 2015. [PMID: 26198296 DOI: 10.1111/mec.13328] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The evolutionary success of reef-building corals is often attributed to their symbiotic relationship with photosynthetic dinoflagellates of the genus Symbiodinium, but metabolic interactions between the partners and the molecular bases of light-enhanced calcification (LEC) are not well understood. Here, the metabolic bases of the interaction between the coral Acropora millepora and its dinoflagellate symbiont were investigated by comparing gene expression levels under light and dark conditions at the whole transcriptome level. Among the 497 differentially expressed genes identified, a suite of genes involved in cholesterol transport was found to be upregulated under light conditions, confirming the significance of this compound in the coral symbiosis. Although ion transporters likely to have roles in calcification were not differentially expressed in this study, expression levels of many genes associated with skeletal organic matrix composition and organization were higher in light conditions. This implies that the rate of organic matrix synthesis is one factor limiting calcification at night. Thus, LEC during the day is likely to be a consequence of increases in both matrix synthesis and the supply of precursor molecules as a result of photosynthetic activity.
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Affiliation(s)
- A Bertucci
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Qld, 4811, Australia
| | - S Forêt
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Qld, 4811, Australia.,Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Bldg. 46, Canberra, ACT, 0200, Australia
| | - E E Ball
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Qld, 4811, Australia.,Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Bldg. 46, Canberra, ACT, 0200, Australia
| | - D J Miller
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Qld, 4811, Australia.,Comparative Genomics Centre and Department of Molecular and Cell Biology, James Cook University, Townsville, Qld, 4811, Australia
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Schoepf V, McCulloch MT, Warner ME, Levas SJ, Matsui Y, Aschaffenburg MD, Grottoli AG. Short-term coral bleaching is not recorded by skeletal boron isotopes. PLoS One 2014; 9:e112011. [PMID: 25396422 PMCID: PMC4232377 DOI: 10.1371/journal.pone.0112011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 10/11/2014] [Indexed: 11/18/2022] Open
Abstract
Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of seawater pH using boron isotopes should be uncompromised by short-term bleaching events.
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Affiliation(s)
- Verena Schoepf
- School of Earth and Environment, The University of Western Australia and ARC Centre of Excellence for Coral Reef Studies, Crawley, WA, Australia
- School of Earth Sciences, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
| | - Malcolm T. McCulloch
- School of Earth and Environment, The University of Western Australia and ARC Centre of Excellence for Coral Reef Studies, Crawley, WA, Australia
| | - Mark E. Warner
- School of Marine Science and Policy, University of Delaware, Lewes, Delaware, United States of America
| | - Stephen J. Levas
- School of Earth Sciences, The Ohio State University, Columbus, Ohio, United States of America
| | - Yohei Matsui
- School of Earth Sciences, The Ohio State University, Columbus, Ohio, United States of America
| | - Matthew D. Aschaffenburg
- School of Marine Science and Policy, University of Delaware, Lewes, Delaware, United States of America
| | - Andréa G. Grottoli
- School of Earth Sciences, The Ohio State University, Columbus, Ohio, United States of America
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Schrameyer V, Wangpraseurt D, Hill R, Kühl M, Larkum AWD, Ralph PJ. Light respiratory processes and gross photosynthesis in two scleractinian corals. PLoS One 2014; 9:e110814. [PMID: 25360746 PMCID: PMC4216011 DOI: 10.1371/journal.pone.0110814] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 09/25/2014] [Indexed: 11/18/2022] Open
Abstract
The light dependency of respiratory activity of two scleractinian corals was examined using O2 microsensors and CO2 exchange measurements. Light respiration increased strongly but asymptotically with elevated irradiance in both species. Light respiration in Pocillopora damicornis was higher than in Pavona decussata under low irradiance, indicating species-specific differences in light-dependent metabolic processes. Overall, the coral P. decussata exhibited higher CO2 uptake rates than P. damicornis over the experimental irradiance range. P. decussata also harboured twice as many algal symbionts and higher total protein biomass compared to P. damicornis, possibly resulting in self-shading of the symbionts and/or changes in host tissue specific light distribution. Differences in light respiration and CO2 availability could be due to host-specific characteristics that modulate the symbiont microenvironment, its photosynthesis, and hence the overall performance of the coral holobiont.
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Affiliation(s)
- Verena Schrameyer
- Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology, Sydney, Ultimo, New South Wales, Australia
| | - Daniel Wangpraseurt
- Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology, Sydney, Ultimo, New South Wales, Australia
| | - Ross Hill
- Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology, Sydney, Ultimo, New South Wales, Australia
- Centre for Marine Bio-Innovation and Sydney Institute of Marine Science, School of Biological, Earth and Environmental Sciences, The University of New South Wales, Sydney, New South Wales, Australia
| | - Michael Kühl
- Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology, Sydney, Ultimo, New South Wales, Australia
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
- Singapore Centre on Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Anthony W. D. Larkum
- Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology, Sydney, Ultimo, New South Wales, Australia
| | - Peter J. Ralph
- Plant Functional Biology and Climate Change Cluster, School of the Environment, University of Technology, Sydney, Ultimo, New South Wales, Australia
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