1
|
Bollati E, Lyndby NH, D'Angelo C, Kühl M, Wiedenmann J, Wangpraseurt D. Green fluorescent protein-like pigments optimize the internal light environment in symbiotic reef building corals. eLife 2022; 11:73521. [PMID: 35801683 PMCID: PMC9342951 DOI: 10.7554/elife.73521] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 07/07/2022] [Indexed: 11/25/2022] Open
Abstract
Pigments homologous to the green fluorescent protein (GFP) have been proposed to fine-tune the internal light microclimate of corals, facilitating photoacclimation of photosynthetic coral symbionts (Symbiodiniaceae) to life in different reef habitats and environmental conditions. However, direct measurements of the in vivo light conditions inside the coral tissue supporting this conclusion are lacking. Here, we quantified the intra-tissue spectral light environment of corals expressing GFP-like proteins from widely different light regimes. We focus on: (1) photoconvertible red fluorescent proteins (pcRFPs), thought to enhance photosynthesis in mesophotic habitats via wavelength conversion, and (2) chromoproteins (CPs), which provide photoprotection to the symbionts in shallow water via light absorption. Optical microsensor measurements indicated that both pigment groups strongly alter the coral intra-tissue light environment. Estimates derived from light spectra measured in pcRFP-containing corals showed that fluorescence emission can contribute to >50% of orange-red light available to the photosynthetic symbionts at mesophotic depths. We further show that upregulation of pink CPs in shallow-water corals during bleaching leads to a reduction of orange light by 10–20% compared to low-CP tissue. Thus, screening by CPs has an important role in mitigating the light-enhancing effect of coral tissue scattering and skeletal reflection during bleaching. Our results provide the first experimental quantification of the importance of GFP-like proteins in fine-tuning the light microclimate of corals during photoacclimation.
Collapse
Affiliation(s)
- Elena Bollati
- Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Niclas H Lyndby
- Laboratory for Biological Geochemistry, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Cecilia D'Angelo
- Coral Reef Laboratory, University of Southampton, Southampton, United Kingdom
| | - Michael Kühl
- Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Jörg Wiedenmann
- Coral Reef Laboratory, University of Southampton, Southampton, United Kingdom
| | - Daniel Wangpraseurt
- Department of NanoEngineering, University of California, San Diego, San Diego, United States
| |
Collapse
|
2
|
Iwasaki K, Szabó M, Tamburic B, Evenhuis C, Zavafer A, Kuzhiumparambil U, Ralph P. Investigating the impact of light quality on macromolecular composition of Chaetoceros muelleri. FUNCTIONAL PLANT BIOLOGY : FPB 2022; 49:554-564. [PMID: 34635201 DOI: 10.1071/fp21131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 09/02/2021] [Indexed: 06/13/2023]
Abstract
Diatoms (Bacillariophyceae) are important to primary productivity of aquatic ecosystems. This algal group is also a valuable source of high value compounds that are utilised as aquaculture feed. The productivity of diatoms is strongly driven by light and CO2 availability, and macro- and micronutrient concentrations. The light dependency of biomass productivity and metabolite composition is well researched in diatoms, but information on the impact of light quality, particularly the productivity return on energy invested when using different monochromatic light sources, remains scarce. In this work, the productivity return on energy invested of improving growth rate, photosynthetic activity, and metabolite productivity of the diatom Chaetoceros muelleri under defined wavelengths (blue, red, and green) as well as while light is analysed. By adjusting the different light qualities to equal photosynthetically utilisable radiation, it was found that the growth rate and photosynthetic oxygen evolution was unchanged under white, blue, and green light, but it was lower under red light. Blue light improved the productivity return on energy invested for biomass, total protein, total lipid, total carbohydrate, and in fatty acids production, which would suggest that blue light should be used for aquaculture feed production.
Collapse
Affiliation(s)
- Kenji Iwasaki
- Climate Change Cluster (C3), Faculty of Science, University of Technology Sydney, NSW, Australia
| | - Milán Szabó
- Climate Change Cluster (C3), Faculty of Science, University of Technology Sydney, NSW, Australia; and Institute of Plant Biology, Biological Research Centre, Hungary, Eötvös Loránd Research Network (ELKH), Szeged, Hungary
| | - Bojan Tamburic
- Water Research Centre, School of Civil and Environmental Engineering, UNSW, Sydney, NSW, Australia
| | - Christian Evenhuis
- Climate Change Cluster (C3), Faculty of Science, University of Technology Sydney, NSW, Australia
| | - Alonso Zavafer
- Climate Change Cluster (C3), Faculty of Science, University of Technology Sydney, NSW, Australia; and Research School of Biology, Australian National University, Canberra, ACT, Australia
| | | | - Peter Ralph
- Climate Change Cluster (C3), Faculty of Science, University of Technology Sydney, NSW, Australia
| |
Collapse
|
3
|
Luo Y, Huang L, Lei X, Yu X, Liu C, Jiang L, Sun Y, Cheng M, Gan J, Zhang Y, Zhou G, Liu S, Lian J, Huang H. Light availability regulated by particulate organic matter affects coral assemblages on a turbid fringing reef. MARINE ENVIRONMENTAL RESEARCH 2022; 177:105613. [PMID: 35429821 DOI: 10.1016/j.marenvres.2022.105613] [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: 09/16/2021] [Revised: 12/08/2021] [Accepted: 03/17/2022] [Indexed: 06/14/2023]
Abstract
Recently, increasing evidence suggests that reef-building corals exposed to elevated suspended solids (SS) are largely structured by changes in underwater light availability (ULA). However, there are few direct and quantitative observations in situ support for this hypothesis; in particular, the contribution of SS to the diffuse attenuation coefficient of the photosynthetically active radiation (Kd-PAR) variations is not yet fully understood. Here, we investigated the variations in ULA, the structure of coral assemblages, and the concentration and composition of SS on the Luhuitou fringing reef, Sanya, China. Light attenuation was rapid (Kd-PAR: 0.60 ± 0.39 m-1) resulting in a shallow euphotic depth (Zeu-PAR) (<11 m). Benthic PAR showed significant positive correlations with branching and corymbose corals (e.g. Acropora spp.), while massive and encrusting species (e.g. Porites spp.) dominated the coral communities and showed no significant correlations with PAR. These results indicate that the depth range available for coral growth is shallow and the tolerance to low-light stress differs among coral species. Notably, Kd-PAR showed no significant correlations with the grain size fractions of SS, whereas significant positive correlations were found with its organic fraction content, demonstrating that the light attenuation of SS is mainly regulated by particulate organic matter (POM). Intriguingly, our isotopic evidence revealed that POM concentration contributed the most to changes in Kd-PAR, with its source being slightly less important. Combined, our results highlight ULA regulated by POM is an important factor in contributing to changes in coral assemblages on inshore turbid reefs, and reducing the input of terrestrial materials, especially POM, is an effective measure to alleviate the low-light stress on sensitive coral species.
Collapse
Affiliation(s)
- Yong Luo
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Lintao Huang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xinming Lei
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; CAS-HKUST Sanya Joint Laboratory of Marine Science Research, Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China; Southern Marine Science and Engineering Guangdong Laboratory Guangzhou, Guangzhou, 511458, China
| | - Xiaolei Yu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chengyue Liu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; CAS-HKUST Sanya Joint Laboratory of Marine Science Research, Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China; Southern Marine Science and Engineering Guangdong Laboratory Guangzhou, Guangzhou, 511458, China
| | - Lei Jiang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; CAS-HKUST Sanya Joint Laboratory of Marine Science Research, Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China; Southern Marine Science and Engineering Guangdong Laboratory Guangzhou, Guangzhou, 511458, China
| | - Youfang Sun
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; CAS-HKUST Sanya Joint Laboratory of Marine Science Research, Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China; Southern Marine Science and Engineering Guangdong Laboratory Guangzhou, Guangzhou, 511458, China
| | - Meng Cheng
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jianfeng Gan
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuyang Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; CAS-HKUST Sanya Joint Laboratory of Marine Science Research, Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China; Southern Marine Science and Engineering Guangdong Laboratory Guangzhou, Guangzhou, 511458, China
| | - Guowei Zhou
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; CAS-HKUST Sanya Joint Laboratory of Marine Science Research, Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China; Southern Marine Science and Engineering Guangdong Laboratory Guangzhou, Guangzhou, 511458, China
| | - Sheng Liu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; CAS-HKUST Sanya Joint Laboratory of Marine Science Research, Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China; Southern Marine Science and Engineering Guangdong Laboratory Guangzhou, Guangzhou, 511458, China
| | - Jiansheng Lian
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; CAS-HKUST Sanya Joint Laboratory of Marine Science Research, Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China; Southern Marine Science and Engineering Guangdong Laboratory Guangzhou, Guangzhou, 511458, China
| | - Hui Huang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China; CAS-HKUST Sanya Joint Laboratory of Marine Science Research, Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Oceanology, SCSIO, Sanya, 572000, China; Sanya National Marine Ecosystem Research Station, Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya, 572000, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
| |
Collapse
|
4
|
Kramer N, Tamir R, Ben‐Zvi O, Jacques SL, Loya Y, Wangpraseurt D. Efficient light‐harvesting of mesophotic corals is facilitated by coral optical traits. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13948] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Raz Tamir
- School of Zoology Tel‐Aviv University Tel Aviv Israel
- The Interuniversity Institute for Marine Sciences of Eilat Eilat Israel
| | - Or Ben‐Zvi
- School of Zoology Tel‐Aviv University Tel Aviv Israel
- The Interuniversity Institute for Marine Sciences of Eilat Eilat Israel
| | - Steven L. Jacques
- Department of Bioengineering University of Washington Seattle WA USA
| | - Yossi Loya
- School of Zoology Tel‐Aviv University Tel Aviv Israel
| | - Daniel Wangpraseurt
- Department of Nanoengineering University of California San Diego San Diego CA USA
- Department of Chemistry University of Cambridge Cambridge UK
| |
Collapse
|
5
|
Taylor Parkins SK, Murthy S, Picioreanu C, Kühl M. Multiphysics modelling of photon, mass and heat transfer in coral microenvironments. J R Soc Interface 2021; 18:20210532. [PMID: 34465209 PMCID: PMC8437025 DOI: 10.1098/rsif.2021.0532] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Coral reefs are constructed by calcifying coral animals that engage in a symbiosis with dinoflagellate microalgae harboured in their tissue. The symbiosis takes place in the presence of steep and dynamic gradients of light, temperature and chemical species that are affected by the structural and optical properties of the coral and their interaction with incident irradiance and water flow. Microenvironmental analyses have enabled quantification of such gradients and bulk coral tissue and skeleton optical properties, but the multi-layered nature of corals and its implications for the optical, thermal and chemical microenvironment remains to be studied in more detail. Here, we present a multiphysics modelling approach, where three-dimensional Monte Carlo simulations of the light field in a simple coral slab morphology with multiple tissue layers were used as input for modelling the heat dissipation and photosynthetic oxygen production driven by photon absorption. By coupling photon, heat and mass transfer, the model predicts light, temperature and O2 gradients in the coral tissue and skeleton, under environmental conditions simulating, for example, tissue contraction/expansion, symbiont loss via coral bleaching or different distributions of coral host pigments. The model reveals basic structure-function mechanisms that shape the microenvironment and ecophysiology of the coral symbiosis in response to environmental change.
Collapse
Affiliation(s)
- Shannara Kayleigh Taylor Parkins
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands.,The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kemitorvet 220, 2800 Kgs. Lyngby, Denmark
| | - Swathi Murthy
- Marine Biology Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Cristian Picioreanu
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands.,Biological and Environmental Sciences and Engineering Division, Water Desalination and Reuse Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Michael Kühl
- Marine Biology Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark.,Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| |
Collapse
|
6
|
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.
Collapse
|
7
|
Host-symbiont combinations dictate the photo-physiological response of reef-building corals to thermal stress. Sci Rep 2019; 9:9985. [PMID: 31292499 PMCID: PMC6620294 DOI: 10.1038/s41598-019-46412-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 06/24/2019] [Indexed: 01/10/2023] Open
Abstract
High sea surface temperatures often lead to coral bleaching wherein reef-building corals lose significant numbers of their endosymbiotic dinoflagellates (Symbiodiniaceae). These increasingly frequent bleaching events often result in large scale coral mortality, thereby devasting reef systems throughout the world. The reef habitats surrounding Palau are ideal for investigating coral responses to climate perturbation, where many inshore bays are subject to higher water temperature as compared with offshore barrier reefs. We examined fourteen physiological traits in response to high temperature across various symbiotic dinoflagellates in four common Pacific coral species, Acropora muricata, Coelastrea aspera, Cyphastrea chalcidicum and Pachyseris rugosa found in both offshore and inshore habitats. Inshore corals were dominated by a single homogenous population of the stress tolerant symbiont Durusdinium trenchii, yet symbiont thermal response and physiology differed significantly across coral species. In contrast, offshore corals harbored specific species of Cladocopium spp. (ITS2 rDNA type-C) yet all experienced similar patterns of photoinactivation and symbiont loss when heated. Additionally, cell volume and light absorption properties increased in heated Cladocopium spp., leading to a greater loss in photo-regulation. While inshore coral temperature response was consistently muted relative to their offshore counterparts, high physiological variability in D. trenchii across inshore corals suggests that bleaching resilience among even the most stress tolerant symbionts is still heavily influenced by their host environment.
Collapse
|
8
|
Wangpraseurt D, Lichtenberg M, Jacques SL, Larkum AWD, Kühl M. Optical Properties of Corals Distort Variable Chlorophyll Fluorescence Measurements. PLANT PHYSIOLOGY 2019; 179:1608-1619. [PMID: 30692219 PMCID: PMC6446749 DOI: 10.1104/pp.18.01275] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 01/16/2019] [Indexed: 06/09/2023]
Abstract
Pulse-amplitude-modulated (PAM) fluorimetry is widely used in photobiological studies of corals, as it rapidly provides numerous photosynthetic parameters to assess coral ecophysiology. Coral optics studies have revealed the presence of light gradients in corals, which are strongly affected by light scattering in coral tissue and skeleton. We investigated whether coral optics affects variable chlorophyll (Chl) fluorescence measurements and derived photosynthetic parameters by developing planar hydrogel slabs with immobilized microalgae and with bulk optical properties similar to those of different types of corals. Our results show that PAM-based measurements of photosynthetic parameters differed substantially between hydrogels with different degrees of light scattering but identical microalgal density, yielding deviations in apparent maximal electron transport rates by a factor of 2. Furthermore, system settings such as the measuring light intensity affected F 0, Fm , and Fv /Fm in hydrogels with identical light absorption but different degrees of light scattering. Likewise, differences in microalgal density affected variable Chl fluorescence parameters, where higher algal densities led to greater Fv /Fm values and relative electron transport rates. These results have important implications for the use of variable Chl fluorimetry in ecophysiological studies of coral stress and photosynthesis, as well as other optically dense systems such as plant tissue and biofilms.
Collapse
Affiliation(s)
- Daniel Wangpraseurt
- Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92037
| | - Mads Lichtenberg
- Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark
| | | | - Anthony W D Larkum
- Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark
- Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales 2007, Australia
| |
Collapse
|
9
|
Smith EG, D'Angelo C, Sharon Y, Tchernov D, Wiedenmann J. Acclimatization of symbiotic corals to mesophotic light environments through wavelength transformation by fluorescent protein pigments. Proc Biol Sci 2017; 284:20170320. [PMID: 28679724 PMCID: PMC5524488 DOI: 10.1098/rspb.2017.0320] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 06/22/2017] [Indexed: 11/17/2022] Open
Abstract
The depth distribution of reef-building corals exposes their photosynthetic symbionts of the genus Symbiodinium to extreme gradients in the intensity and spectral quality of the ambient light environment. Characterizing the mechanisms used by the coral holobiont to respond to the low intensity and reduced spectral composition of the light environment in deeper reefs (greater than 20 m) is fundamental to our understanding of the functioning and structure of reefs across depth gradients. Here, we demonstrate that host pigments, specifically photoconvertible red fluorescent proteins (pcRFPs), can promote coral adaptation/acclimatization to deeper-water light environments by transforming the prevalent blue light into orange-red light, which can penetrate deeper within zooxanthellae-containing tissues; this facilitates a more homogeneous distribution of photons across symbiont communities. The ecological importance of pcRFPs in deeper reefs is supported by the increasing proportion of red fluorescent corals with depth (measured down to 45 m) and increased survival of colour morphs with strong expression of pcRFPs in long-term light manipulation experiments. In addition to screening by host pigments from high light intensities in shallow water, the spectral transformation observed in deeper-water corals highlights the importance of GFP-like protein expression as an ecological mechanism to support the functioning of the coral-Symbiodinium association across steep environmental gradients.
Collapse
Affiliation(s)
- Edward G Smith
- Coral Reef Laboratory, Ocean and Earth Science, University of Southampton, European Way, Southampton SO14 3ZH, UK
- Marine Biology Laboratory/Centre for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Cecilia D'Angelo
- Coral Reef Laboratory, Ocean and Earth Science, University of Southampton, European Way, Southampton SO14 3ZH, UK
- IfLS, Institute for Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| | - Yoni Sharon
- The Interuniversity Institute for Marine Sciences of Eilat, Eilat, Israel
| | - Dan Tchernov
- The Interuniversity Institute for Marine Sciences of Eilat, Eilat, Israel
- Department of Marine Biology, University of Haifa, 31905 Mt Carmel, Israel
| | - Joerg Wiedenmann
- Coral Reef Laboratory, Ocean and Earth Science, University of Southampton, European Way, Southampton SO14 3ZH, UK
- IfLS, Institute for Life Sciences, University of Southampton, Life Sciences Building 85, Highfield, Southampton SO17 1BJ, UK
| |
Collapse
|
10
|
Wangpraseurt D, Holm JB, Larkum AWD, Pernice M, Ralph PJ, Suggett DJ, Kühl M. In vivo Microscale Measurements of Light and Photosynthesis during Coral Bleaching: Evidence for the Optical Feedback Loop? Front Microbiol 2017; 8:59. [PMID: 28174567 PMCID: PMC5258690 DOI: 10.3389/fmicb.2017.00059] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 01/09/2017] [Indexed: 12/21/2022] Open
Abstract
Climate change-related coral bleaching, i.e., the visible loss of zooxanthellae from the coral host, is increasing in frequency and extent and presents a major threat to coral reefs globally. Coral bleaching has been proposed to involve accelerating light stress of their microalgal endosymbionts via a positive feedback loop of photodamage, symbiont expulsion and excess in vivo light exposure. To test this hypothesis, we used light and O2 microsensors to characterize in vivo light exposure and photosynthesis of Symbiodinium during a thermal stress experiment. We created tissue areas with different densities of Symbiodinium cells in order to understand the optical properties and light microenvironment of corals during bleaching. Our results showed that in bleached Pocillopora damicornis corals, Symbiodinium light exposure was up to fivefold enhanced relative to healthy corals, and the relationship between symbiont loss and light enhancement was well-described by a power-law function. Cell-specific rates of Symbiodinium gross photosynthesis and light respiration were enhanced in bleached P. damicornis compared to healthy corals, while areal rates of net photosynthesis decreased. Symbiodinium light exposure in Favites sp. revealed the presence of low light microniches in bleached coral tissues, suggesting that light scattering in thick coral tissues can enable photoprotection of cryptic symbionts. Our study provides evidence for the acceleration of in vivo light exposure during coral bleaching but this optical feedback mechanism differs between coral hosts. Enhanced photosynthesis in relation to accelerating light exposure shows that coral microscale optics exerts a key role on coral photophysiology and the subsequent degree of radiative stress during coral bleaching.
Collapse
Affiliation(s)
- Daniel Wangpraseurt
- Marine Biological Section, Department of Biology, University of CopenhagenHelsingør, Denmark; Climate Change Cluster, Department of Environmental Sciences, University of Sydney, SydneyNSW, Australia
| | - Jacob B Holm
- Marine Biological Section, Department of Biology, University of Copenhagen Helsingør, Denmark
| | - Anthony W D Larkum
- Climate Change Cluster, Department of Environmental Sciences, University of Sydney, Sydney NSW, Australia
| | - Mathieu Pernice
- Climate Change Cluster, Department of Environmental Sciences, University of Sydney, Sydney NSW, Australia
| | - Peter J Ralph
- Climate Change Cluster, Department of Environmental Sciences, University of Sydney, Sydney NSW, Australia
| | - David J Suggett
- Climate Change Cluster, Department of Environmental Sciences, University of Sydney, Sydney NSW, Australia
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of CopenhagenHelsingør, Denmark; Climate Change Cluster, Department of Environmental Sciences, University of Sydney, SydneyNSW, Australia
| |
Collapse
|
11
|
Lyndby NH, Kühl M, Wangpraseurt D. Heat generation and light scattering of green fluorescent protein-like pigments in coral tissue. Sci Rep 2016; 6:26599. [PMID: 27225857 PMCID: PMC4880895 DOI: 10.1038/srep26599] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 05/05/2016] [Indexed: 11/29/2022] Open
Abstract
Green fluorescent protein (GFP)-like pigments have been proposed to have beneficial effects on coral photobiology. Here, we investigated the relationships between green fluorescence, coral heating and tissue optics for the massive coral Dipsastraea sp. (previously Favia sp.). We used microsensors to measure tissue scalar irradiance and temperature along with hyperspectral imaging and combined imaging of variable chlorophyll fluorescence and green fluorescence. Green fluorescence correlated positively with coral heating and scalar irradiance enhancement at the tissue surface. Coral tissue heating saturated for maximal levels of green fluorescence. The action spectrum of coral surface heating revealed that heating was highest under red (peaking at 680 nm) irradiance. Scalar irradiance enhancement in coral tissue was highest when illuminated with blue light, but up to 62% (for the case of highest green fluorescence) of this photon enhancement was due to green fluorescence emission. We suggest that GFP-like pigments scatter the incident radiation, which enhances light absorption and heating of the coral. However, heating saturates, because intense light scattering reduces the vertical penetration depth through the tissue eventually leading to reduced light absorption at high fluorescent pigment density. We conclude that fluorescent pigments can have a central role in modulating coral light absorption and heating.
Collapse
Affiliation(s)
- Niclas H Lyndby
- Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark.,Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, New South Wales 2007, Australia
| | - Daniel Wangpraseurt
- Marine Biological Section, Department of Biology, University of Copenhagen, DK-3000 Helsingør, Denmark.,Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, New South Wales 2007, Australia
| |
Collapse
|
12
|
Lichtenberg M, Larkum AWD, Kühl M. Photosynthetic Acclimation of Symbiodinium in hospite Depends on Vertical Position in the Tissue of the Scleractinian Coral Montastrea curta. Front Microbiol 2016; 7:230. [PMID: 26955372 PMCID: PMC4768073 DOI: 10.3389/fmicb.2016.00230] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 02/12/2016] [Indexed: 01/26/2023] Open
Abstract
Coral photophysiology has been studied intensively from the colony scale down to the scale of single fluorescent pigment granules as light is one of the key determinants for coral health. We studied the photophysiology of the oral and aboral symbiont band of scleractinian coral Montastrea curta to investigate if different acclimation to light exist in hospite on a polyp scale. By combined use of electrochemical and fiber-optic microsensors for O2, scalar irradiance and variable chlorophyll fluorescence, we could characterize the physical and chemical microenvironment experienced by the symbionts and, for the first time, estimate effective quantum yields of PSII photochemistry and rates of electron transport at the position of the zooxanthellae corrected for the in-tissue gradient of scalar irradiance. The oral- and aboral Symbiodinium layers received ∼71% and ∼33% of surface scalar irradiance, respectively, and the two symbiont layers experience considerable differences in light exposure. Rates of gross photosynthesis did not differ markedly between the oral- and aboral layer and curves of PSII electron transport rates corrected for scalar irradiance in hospite, showed that the light use efficiency under sub-saturating light conditions were similar between the two layers. However, the aboral Symbiodinium band did not experience photosynthetic saturation, even at the highest investigated irradiance where the oral layer was clearly saturated. We thus found a different light acclimation response for the oral and aboral symbiont bands in hospite, and discuss whether such response could be shaped by spectral shifts caused by tissue gradients of scalar irradiance. Based on our experimental finding, combined with previous knowledge, we present a conceptual model on the photophysiology of Symbiodinium residing inside living coral tissue under natural gradients of light and chemical parameters.
Collapse
Affiliation(s)
- Mads Lichtenberg
- Marine Biological Section, Department of Biology, University of Copenhagen Helsingør, Denmark
| | - Anthony W D Larkum
- Plant Functional Biology and Climate Change Cluster (C3), University of Technology Sydney Sydney, NSW, Australia
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of CopenhagenHelsingør, Denmark; Plant Functional Biology and Climate Change Cluster (C3), University of Technology SydneySydney, NSW, Australia
| |
Collapse
|
13
|
Jones R, Bessell-Browne P, Fisher R, Klonowski W, Slivkoff M. Assessing the impacts of sediments from dredging on corals. MARINE POLLUTION BULLETIN 2016; 102:9-29. [PMID: 26654296 DOI: 10.1016/j.marpolbul.2015.10.049] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 10/19/2015] [Accepted: 10/22/2015] [Indexed: 06/05/2023]
Abstract
There is a need to develop water quality thresholds for dredging near coral reefs that can relate physical pressures to biological responses and define exposure conditions above which effects could occur. Water quality characteristics during dredging have, however, not been well described. Using information from several major dredging projects, we describe sediment particle sizes in the water column/seabed, suspended sediment concentrations at different temporal scales during natural and dredging-related turbidity events, and changes in light quantity/quality underneath plumes. These conditions differ considerably from those used in past laboratory studies of the effects of sediments on corals. The review also discusses other problems associated with using information from past studies for developing thresholds such as the existence of multiple different and inter-connected cause-effect pathways (which can confuse/confound interpretations), the use of sediment proxies, and the reliance on information from sediment traps to justify exposure regimes in sedimentation experiments.
Collapse
Affiliation(s)
- Ross Jones
- Australian Institute of Marine Science (AIMS), Perth, Australia; Western Australian Marine Science Institution, Perth, Australia.
| | - Pia Bessell-Browne
- Australian Institute of Marine Science (AIMS), Perth, Australia; Centre of Microscopy, Charaterisation and Analysis, The University of Western Australia, Perth, Australia; Western Australian Marine Science Institution, Perth, Australia
| | - Rebecca Fisher
- Australian Institute of Marine Science (AIMS), Perth, Australia; Curtin University, Bentley, Perth, Australia
| | - Wojciech Klonowski
- Curtin University, Bentley, Perth, Australia; In situ Marine Optics, Bibra Lake, Perth, Australia
| | - Matthew Slivkoff
- Curtin University, Bentley, Perth, Australia; In situ Marine Optics, Bibra Lake, Perth, Australia
| |
Collapse
|