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Wright LS, Simpkins T, Filbee-Dexter K, Wernberg T. Temperature sensitivity of detrital photosynthesis. Ann Bot 2024; 133:17-28. [PMID: 38142363 PMCID: PMC10921823 DOI: 10.1093/aob/mcad167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/24/2023] [Accepted: 11/22/2023] [Indexed: 12/25/2023]
Abstract
BACKGROUND AND AIMS Kelp forests are increasingly considered blue carbon habitats for ocean-based biological carbon dioxide removal, but knowledge gaps remain in our understanding of their carbon cycle. Of particular interest is the remineralization of detritus, which can remain photosynthetically active. Here, we study a widespread, thermotolerant kelp (Ecklonia radiata) to explore detrital photosynthesis as a mechanism underlying temperature and light as two key drivers of remineralization. METHODS We used meta-analysis to constrain the thermal optimum (Topt) of E. radiata. Temperature and light were subsequently controlled over a 119-day ex situ decomposition experiment. Flow-through experimental tanks were kept in darkness at 15 °C or under a subcompensating maximal irradiance of 8 µmol photons m-2 s-1 at 15, 20 or 25 °C. Photosynthesis of laterals (analogues to leaves) was estimated using closed-chamber oxygen evolution in darkness and under a saturating irradiance of 420 µmol photons m-2 s-1. KEY RESULTS T opt of E. radiata is 18 °C across performance variables (photosynthesis, growth, abundance, size, mass and fertility), life stages (gametophyte and sporophyte) and populations. Our models predict that a temperature of >15 °C reduces the potential for E. radiata detritus to be photosynthetically viable, hence detrital Topt ≤ 15 °C. Detritus is viable under subcompensating irradiance, where it performs better than in darkness. Comparison of net and gross photosynthesis indicates that elevated temperature primarily decreases detrital photosynthesis, whereas darkness primarily increases detrital respiration compared with optimal experimental conditions, in which detrital photosynthesis can persist for ≥119 days. CONCLUSIONS T opt of kelp detritus is ≥3 °C colder than that of the intact plant. Given that E. radiata is one of the most temperature-tolerant kelps, this suggests that photosynthesis is generally more thermosensitive in the detrital phase, which partly explains the enhancing effect of temperature on remineralization. In contrast to darkness, even subcompensating irradiance maintains detrital viability, elucidating the accelerating effect of depth and its concomitant light reduction on remineralization to some extent. Detrital photosynthesis is a meaningful mechanism underlying at least two drivers of remineralization, even below the photoenvironment inhabited by the attached alga.
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Affiliation(s)
- Luka Seamus Wright
- Oceans Institute, University of Western Australia, Perth,Australia
- School of Biological Sciences, University of Western Australia, Perth,Australia
| | - Taylor Simpkins
- Oceans Institute, University of Western Australia, Perth,Australia
- School of Biological Sciences, University of Western Australia, Perth,Australia
| | - Karen Filbee-Dexter
- Oceans Institute, University of Western Australia, Perth,Australia
- School of Biological Sciences, University of Western Australia, Perth,Australia
- Institute of Marine Research, His, Norway
| | - Thomas Wernberg
- Oceans Institute, University of Western Australia, Perth,Australia
- School of Biological Sciences, University of Western Australia, Perth,Australia
- Institute of Marine Research, His, Norway
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2
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Sands E, Davies S, Puxty RJ, Vergé V, Bouget FY, Scanlan DJ, Carré IA. Genetic and physiological responses to light quality in a deep ocean ecotype of Ostreococcus, an ecologically important photosynthetic picoeukaryote. J Exp Bot 2023; 74:6773-6789. [PMID: 37658791 PMCID: PMC10662239 DOI: 10.1093/jxb/erad347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 08/31/2023] [Indexed: 09/05/2023]
Abstract
Phytoplankton are exposed to dramatic variations in light quality when cells are carried by upwelling or downwelling currents or encounter sediment. We investigated the potential impact of light quality changes in Ostreococcus, a key marine photosynthetic picoeukaryote, by analysing changes in its transcriptome, pigment content, and photophysiology after acclimation to monochromatic red, green, or blue light. The clade B species RCC809, isolated from the deep euphotic zone of the tropical Atlantic Ocean, responded to blue light by accelerating cell division at the expense of storage reserves and by increasing the relative level of blue-light-absorbing pigments. It responded to red and green light by increasing its potential for photoprotection. In contrast, the clade A species OTTH0595, which originated from a shallow water environment, showed no difference in photosynthetic properties and minor differences in carotenoid contents between light qualities. This was associated with the loss of candidate light-quality responsive promoter motifs identified in RCC809 genes. These results demonstrate that light quality can have a major influence on the physiology of eukaryotic phytoplankton and suggest that different light quality environments can drive selection for diverse patterns of responsiveness and environmental niche partitioning.
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Affiliation(s)
- Elizabeth Sands
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | - Sian Davies
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK
| | | | - Valerie Vergé
- Université Pierre et Marie Curie, Paris 06, UMR 7621, Laboratoire d’Océanographie Microbienne, Observatoire Océanologique, Banyuls sur Mer, France
| | - François-Yves Bouget
- Université Pierre et Marie Curie, Paris 06, UMR 7621, Laboratoire d’Océanographie Microbienne, Observatoire Océanologique, Banyuls sur Mer, France
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3
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van Hees D, Hanneman C, Paradis S, Camara AG, Matsumoto M, Hamilton T, Krueger-Hadfield SA, Kodner RB. Patchy and Pink: Dynamics of a Chlainomonas sp. (Chlamydomonadales, chlorophyta) algal bloom on Bagley Lake, North Cascades, WA. FEMS Microbiol Ecol 2023; 99:fiad106. [PMID: 37675994 PMCID: PMC10580270 DOI: 10.1093/femsec/fiad106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 08/18/2023] [Accepted: 09/06/2023] [Indexed: 09/08/2023] Open
Abstract
Snow algal blooms frequently occur throughout alpine and polar environments during spring and summer months; however, our understanding of bloom dynamics is limited. We tracked a recurrent bloom of Chlainomonas sp. on Upper Bagley Lake in the North Cascade Mountains, USA, to assess the spatiotemporal dynamics in bloom color intensity, community photophysiology, and community composition over eight weeks. We found that the algae biomass had a dynamic patchy distribution over space and time, which was decoupled from changes in community composition and life-cycle progress averaged across the bloom. The proportional representation of Chlainomonas sp. remained consistent throughout the study while the overall community composition shows a progression through the bloom. We found that community photophysiology, measured by the maximum quantum yield of PSII (Fv/Fm), decreased on average throughout the bloom. These findings suggest that the Chlainomonas sp. community on Bagley Lake is not simply an algal bloom with rapid increase in biomass followed by a population crash, as is often seen in aquatic systems, though there is a physiological trajectory and sensitivity to environmental stress. These results contribute to our understanding of the biology of Chlainomonas sp. and its response to environmental stress, specifically an extreme warming event.
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Affiliation(s)
- Dan van Hees
- Biology Department, Western Washington University, Bellingham, WA 98225, United States
| | - Clare Hanneman
- Biology Department, Western Washington University, Bellingham, WA 98225, United States
| | - Sophie Paradis
- Biology Department, Western Washington University, Bellingham, WA 98225, United States
| | - A G Camara
- Biology Department, Western Washington University, Bellingham, WA 98225, United States
| | - Maya Matsumoto
- Biology Department, Western Washington University, Bellingham, WA 98225, United States
| | - Trinity Hamilton
- Department of Plant and Microbial Biology and the BioTechnology Institute, University of Minnesota
St. Paul, MN 55108, United States
| | - Stacy A Krueger-Hadfield
- Department of Biology, The University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Robin B Kodner
- Environmental Science, Western Washington University, Bellingham, WA 98225, United States
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4
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Broadwell ELM, Pickford RE, Perkins RG, Sgouridis F, Williamson CJ. Adaptation versus plastic responses to temperature, light, and nitrate availability in cultured snow algal strains. FEMS Microbiol Ecol 2023; 99:fiad088. [PMID: 37553143 PMCID: PMC10481995 DOI: 10.1093/femsec/fiad088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 06/29/2023] [Accepted: 08/07/2023] [Indexed: 08/10/2023] Open
Abstract
Snow algal blooms are widespread, dominating low temperature, high light, and oligotrophic melting snowpacks. Here, we assessed the photophysiological and cellular stoichiometric responses of snow algal genera Chloromonas spp. and Microglena spp. in their vegetative life stage isolated from the Arctic and Antarctic to gradients in temperature (5 - 15°C), nitrate availability (1 - 10 µmol L-1), and light (50 and 500 µmol photons m-2 s-1). When grown under gradients in temperature, measured snow algal strains displayed Fv/Fm values increased by ∼115% and electron transport rates decreased by ∼50% at 5°C compared to 10 and 15°C, demonstrating how low temperatures can mimic high light impacts to photophysiology. When using carrying capacity as opposed to growth rate as a metric for determining the temperature optima, these snow algal strains can be defined as psychrophilic, with carrying capacities ∼90% higher at 5°C than warmer temperatures. All strains approached Redfield C:N stoichiometry when cultured under nutrient replete conditions regardless of temperature (5.7 ± 0.4 across all strains), whereas significant increases in C:N were apparent when strains were cultured under nitrate concentrations that reflected in situ conditions (17.8 ± 5.9). Intra-specific responses in photophysiology were apparent under high light with Chloromonas spp. more capable of acclimating to higher light intensities. These findings suggest that in situ conditions are not optimal for the studied snow algal strains, but they are able to dynamically adjust both their photochemistry and stoichiometry to acclimate to these conditions.
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Affiliation(s)
- Emily L M Broadwell
- School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, United Kingdom
| | - Rachel E Pickford
- School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, United Kingdom
| | - Rupert G Perkins
- School of Earth and Environmental Sciences, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, United Kingdom
| | - Fotis Sgouridis
- School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, United Kingdom
| | - Christopher J Williamson
- School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, United Kingdom
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Mendes CRB, Costa RR, Ferreira A, Jesus B, Tavano VM, Dotto TS, Leal MC, Kerr R, Islabão CA, Franco ADODR, Mata MM, Garcia CAE, Secchi ER. Cryptophytes: An emerging algal group in the rapidly changing Antarctic Peninsula marine environments. Glob Chang Biol 2023; 29:1791-1808. [PMID: 36656050 DOI: 10.1111/gcb.16602] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 11/24/2022] [Accepted: 01/07/2023] [Indexed: 05/28/2023]
Abstract
The western Antarctic Peninsula (WAP) is a climatically sensitive region where foundational changes at the basis of the food web have been recorded; cryptophytes are gradually outgrowing diatoms together with a decreased size spectrum of the phytoplankton community. Based on a 11-year (2008-2018) in-situ dataset, we demonstrate a strong coupling between biomass accumulation of cryptophytes, summer upper ocean stability, and the mixed layer depth. Our results shed light on the environmental conditions favoring the cryptophyte success in coastal regions of the WAP, especially during situations of shallower mixed layers associated with lower diatom biomass, which evidences a clear competition or niche segregation between diatoms and cryptophytes. We also unravel the cryptophyte photo-physiological niche by exploring its capacity to thrive under high light stress normally found in confined stratified upper layers. Such conditions are becoming more frequent in the Antarctic coastal waters and will likely have significant future implications at various levels of the marine food web. The competitive advantage of cryptophytes in environments with significant light level fluctuations was supported by laboratory experiments that revealed a high flexibility of cryptophytes to grow in different light conditions driven by a fast photo-regulating response. All tested physiological parameters support the hypothesis that cryptophytes are highly flexible regarding their growing light conditions and extremely efficient in rapidly photo-regulating changes to environmental light levels. This plasticity would give them a competitive advantage in exploiting an ecological niche where light levels fluctuate quickly. These findings provide new insights on niche separation between diatoms and cryptophytes, which is vital for a thorough understanding of the WAP marine ecosystem.
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Affiliation(s)
- Carlos Rafael Borges Mendes
- Laboratório de Fitoplâncton e Microorganismos Marinhos, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
- Laboratório de Estudo dos Oceanos e Clima, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
| | - Raul Rodrigo Costa
- Laboratório de Fitoplâncton e Microorganismos Marinhos, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
- Laboratório de Estudo dos Oceanos e Clima, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
| | - Afonso Ferreira
- Laboratório de Fitoplâncton e Microorganismos Marinhos, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
- Faculdade de Ciências, MARE - Centro de Ciências do Mar e do Ambiente, Universidade de Lisboa, Lisboa, Portugal
| | - Bruno Jesus
- Laboratoire Mer Molécules Santé, Faculté des Sciences et des Techniques, Université de Nantes, Nantes, France
| | - Virginia Maria Tavano
- Laboratório de Fitoplâncton e Microorganismos Marinhos, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
- Laboratório de Estudo dos Oceanos e Clima, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
| | - Tiago Segabinazzi Dotto
- Centre for Ocean and Atmospheric Sciences, School of Environmental Sciences, University of East Anglia, Norwich, UK
| | - Miguel Costa Leal
- Departamento de Biologia, ECOMARE, CESAM - Centre for Environmental and Marine Studies, Universidade de Aveiro, Aveiro, Portugal
| | - Rodrigo Kerr
- Laboratório de Estudo dos Oceanos e Clima, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
| | - Carolina Antuarte Islabão
- Laboratório de Fitoplâncton e Microorganismos Marinhos, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
| | - Andréa de Oliveira da Rocha Franco
- Laboratório de Fitoplâncton e Microorganismos Marinhos, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
| | - Mauricio M Mata
- Laboratório de Estudo dos Oceanos e Clima, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
| | - Carlos Alberto Eiras Garcia
- Laboratório de Estudo dos Oceanos e Clima, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
| | - Eduardo Resende Secchi
- Laboratório de Ecologia e Conservação da Megafauna Marinha, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Rio Grande do Sul, Rio Grande, Brazil
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6
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Paight C, Johnson MD, Lasek-Nesselquist E, Moeller HV. Cascading effects of prey identity on gene expression in a kleptoplastidic ciliate. J Eukaryot Microbiol 2023; 70:e12940. [PMID: 35975609 PMCID: PMC10087830 DOI: 10.1111/jeu.12940] [Citation(s) in RCA: 0] [Impact Index Per Article: 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: 04/12/2022] [Revised: 07/14/2022] [Accepted: 08/05/2022] [Indexed: 01/13/2023]
Abstract
Kleptoplastidic, or chloroplast stealing, lineages transiently retain functional photosynthetic machinery from algal prey. This machinery, and its photosynthetic outputs, must be integrated into the host's metabolism, but the details of this integration are poorly understood. Here, we study this metabolic integration in the ciliate Mesodinium chamaeleon, a coastal marine species capable of retaining chloroplasts from at least six distinct genera of cryptophyte algae. To assess the effects of feeding history on ciliate physiology and gene expression, we acclimated M. chamaeleon to four different types of prey and contrasted well-fed and starved treatments. Consistent with previous physiological work on the ciliate, we found that starved ciliates had lower chlorophyll content, photosynthetic rates, and growth rates than their well-fed counterparts. However, ciliate gene expression mirrored prey phylogenetic relationships rather than physiological status, suggesting that, even as M. chamaeleon cells were starved of prey, their overarching regulatory systems remained tuned to the prey type to which they had been acclimated. Collectively, our results indicate a surprising degree of prey-specific host transcriptional adjustments, implying varied integration of prey metabolic potential into many aspects of ciliate physiology.
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Affiliation(s)
- Christopher Paight
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, California, USA
| | - Matthew D Johnson
- Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
| | - Erica Lasek-Nesselquist
- Wadsworth Center, NYSDOH, Albany, New York, USA.,Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Rensselaer, New York, USA
| | - Holly V Moeller
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, California, USA
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Doucette VE, Rodriguez Bravo LM, Altieri AH, Johnson MD. Negative effects of a zoanthid competitor limit coral calcification more than ocean acidification. R Soc Open Sci 2022; 9:220760. [PMID: 36425521 PMCID: PMC9682307 DOI: 10.1098/rsos.220760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 11/01/2022] [Indexed: 06/16/2023]
Abstract
Ocean acidification (OA) threatens the persistence of reef-building corals and the habitat they provide. While species-specific effects of OA on marine organisms could have cascading effects on ecological interactions like competition, few studies have identified how benthic reef competitors respond to OA. We explored how two common Caribbean competitors, branching Porites and a colonial zoanthid (Zoanthus), respond to the factorial combination of OA and competition. In the laboratory, we exposed corals, zoanthids and interacting corals and zoanthids to ambient (8.01 ± 0.03) and OA (7.68 ± 0.07) conditions for 60 days. The OA treatment had no measured effect on zoanthids or coral calcification but decreased Porites maximum PSII efficiency. Conversely, the competitive interaction significantly decreased Porites calcification but had minimal-to-no countereffects on the zoanthid. Although this interaction was not exacerbated by the 60-day OA exposure, environmental changes that enhance zoanthid performance could add to the dominance of zoanthids over corals. The lack of effects of OA on coral calcification indicates that near-term competitive interactions may have more immediate consequences for some corals than future global change scenarios. Disparate consequences of competition have implications for community structure and should be accounted for when evaluating local coral reef trajectories.
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Affiliation(s)
| | - Lucia M. Rodriguez Bravo
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancon, Republic of Panama
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Andrew H. Altieri
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancon, Republic of Panama
- Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL, USA
| | - Maggie D. Johnson
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancon, Republic of Panama
- Red Sea Research Center, Biological and Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- Tenenbaum Marine Observatories Network, Smithsonian Institution, Edgewater, MD, USA
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Wright LS, Pessarrodona A, Foggo A. Climate-driven shifts in kelp forest composition reduce carbon sequestration potential. Glob Chang Biol 2022; 28:5514-5531. [PMID: 35694894 PMCID: PMC9545355 DOI: 10.1111/gcb.16299] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [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: 04/24/2022] [Revised: 05/31/2022] [Accepted: 06/05/2022] [Indexed: 05/27/2023]
Abstract
The potential contribution of kelp forests to blue carbon sinks is currently of great interest but interspecific variance has received no attention. In the temperate Northeast Atlantic, kelp forest composition is changing due to climate-driven poleward range shifts of cold temperate Laminaria digitata and Laminaria hyperborea and warm temperate Laminaria ochroleuca. To understand how this might affect the carbon sequestration potential (CSP) of this ecosystem, we quantified interspecific differences in carbon export and decomposition alongside changes in detrital photosynthesis and biochemistry. We found that while warm temperate kelp exports up to 71% more carbon per plant, it decomposes up to 155% faster than its boreal congeners. Elemental stoichiometry and polyphenolic content cannot fully explain faster carbon turnover, which may be attributable to contrasting tissue toughness or unknown biochemical and structural defenses. Faster decomposition causes the detrital photosynthetic apparatus of L. ochroleuca to be overwhelmed 20 days after export and lose integrity after 36 days, while detritus of cold temperate species maintains carbon assimilation. Depending on the photoenvironment, detrital photosynthesis could further exacerbate interspecific differences in decomposition via a potential positive feedback loop. Through compositional change such as the predicted prevalence of L. ochroleuca, ocean warming may therefore reduce the CSP of such temperate marine forests.
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Affiliation(s)
- Luka Seamus Wright
- Marine Biology and Ecology Research CentreUniversity of PlymouthPlymouthUK
- Oceans InstituteUniversity of Western AustraliaPerthWestern AustraliaAustralia
| | - Albert Pessarrodona
- Oceans InstituteUniversity of Western AustraliaPerthWestern AustraliaAustralia
| | - Andy Foggo
- Marine Biology and Ecology Research CentreUniversity of PlymouthPlymouthUK
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Zhu Y, Feng Y, Browning TJ, Wen Z, Hughes DJ, Hao Q, Zhang R, Meng Q, Wells ML, Jiang Z, Dissanayake PAKN, Priyadarshani WNC, Shou L, Zeng J, Chai F. Exploring Variability of Trichodesmium Photophysiology Using Multi-Excitation Wavelength Fast Repetition Rate Fluorometry. Front Microbiol 2022; 13:813573. [PMID: 35464918 PMCID: PMC9026164 DOI: 10.3389/fmicb.2022.813573] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 02/11/2022] [Indexed: 11/20/2022] Open
Abstract
Fast repetition rate fluorometry (FRRf) allows for rapid non-destructive assessment of phytoplankton photophysiology in situ yet has rarely been applied to Trichodesmium. This gap reflects long-standing concerns that Trichodesmium (and other cyanobacteria) contain pigments that are less effective at absorbing blue light which is often used as the sole excitation source in FRR fluorometers-potentially leading to underestimation of key fluorescence parameters. In this study, we use a multi-excitation FRR fluorometer (equipped with blue, green, and orange LEDs) to investigate photophysiological variability in Trichodesmium assemblages from two sites. Using a multi-LED measurement protocol (447+519+634 nm combined), we assessed maximum photochemical efficiency (F v /F m ), functional absorption cross section of PSII (σ PSII ), and electron transport rates (ETRs) for Trichodesmium assemblages in both the Northwest Pacific (NWP) and North Indian Ocean in the vicinity of Sri Lanka (NIO-SL). Evaluating fluorometer performance, we showed that use of a multi-LED measuring protocol yields a significant increase of F v /F m for Trichodesmium compared to blue-only excitation. We found distinct photophysiological differences for Trichodesmium at both locations with higher average F v /F m as well as lower σ PSII and non-photochemical quenching (NPQ NSV ) observed in the NWP compared to the NIO-SL (Kruskal-Wallis t-test df = 1, p < 0.05). Fluorescence light response curves (FLCs) further revealed differences in ETR response with a lower initial slope (α ETR ) and higher maximum electron turnover rate ( E T R P S I I m a x ) observed for Trichodesmium in the NWP compared to the NIO-SL, translating to a higher averaged light saturation E K (= E T R P S I I m a x /α ETR ) for cells at this location. Spatial variations in physiological parameters were both observed between and within regions, likely linked to nutrient supply and physiological stress. Finally, we applied an algorithm to estimate primary productivity of Trichodesmium using FRRf-derived fluorescence parameters, yielding an estimated carbon-fixation rate ranging from 7.8 to 21.1 mgC mg Chl-a-1 h-1 across this dataset. Overall, our findings demonstrate that capacity of multi-excitation FRRf to advance the application of Chl-a fluorescence techniques in phytoplankton assemblages dominated by cyanobacteria and reveals novel insight into environmental regulation of photoacclimation in natural Trichodesmium populations.
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Affiliation(s)
- Yuanli Zhu
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Yuanyuan Feng
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Thomas J. Browning
- Marine Biogeochemistry Division, GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany
| | - Zuozhu Wen
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - David J. Hughes
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - Qiang Hao
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Ruifeng Zhang
- School of Oceanography, Shanghai Jiao Tong University, Shanghai, China
| | - Qicheng Meng
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Mark L. Wells
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
- Darling Marine Center, University of Maine, Walpole, ME, United States
| | - Zhibing Jiang
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - P. A. K. N. Dissanayake
- Department of Oceanography and Marine Geology, Faculty of Fisheries and Marine Sciences and Technology, University of Ruhuna, Matara, Sri Lanka
| | - W. N. C. Priyadarshani
- National Institute of Oceanography and Marine Sciences, National Aquatic Resources Research and Development Agency, Colombo, Sri Lanka
| | - Lu Shou
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Jiangning Zeng
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
| | - Fei Chai
- State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China
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Léger-Daigle R, Noisette F, Bélanger S, Cusson M, Nozais C. Photoacclimation and Light Thresholds for Cold Temperate Seagrasses. Front Plant Sci 2022; 13:805065. [PMID: 35222470 PMCID: PMC8866642 DOI: 10.3389/fpls.2022.805065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 01/11/2022] [Indexed: 06/14/2023]
Abstract
Water quality deterioration is expected to worsen the light conditions in shallow coastal waters with increasing human activities. Temperate seagrasses are known to tolerate a highly fluctuating light environment. However, depending on their ability to adjust to some decline in light conditions, decreases in daily light quantity and quality could affect seagrass physiology, productivity, and, eventually, survival if the Minimum Quantum Requirements (MQR) are not reached. To better understand if, how, and to what extent photosynthetic adjustments contribute to light acclimation, eelgrass (Zostera marina L.) shoots from the cold temperate St. Lawrence marine estuary (Rimouski, QC, Canada) were exposed to seven light intensity treatments (6, 36, 74, 133, 355, 503, and 860 μmol photons m-2 s-1, 14:10 light:dark photoperiod). Photosynthetic capacity and efficiency were quantified after five and 25 days of light exposure by Pulse Amplitude Modulated (PAM) fluorometry to assess the rapid response of the photosynthetic apparatus and its acclimation potential. Photoacclimation was also studied through physiological responses of leaves and shoots (gross and net primary production, pigment content, and light absorption). Shoots showed proof of photosynthetic adjustments at irradiances below 200 μmol photons m-2 s-1, which was identified as the threshold between limiting and saturating irradiances. Rapid Light Curves (RLC) and net primary production (NPP) rates revealed sustained maximal photosynthetic rates from the highest light treatments down to 74 μmol photons m-2 s-1, while a compensation point (NPP = 0) of 13.7 μmol photons m-2 s-1 was identified. In addition, an important package effect was observed, since an almost three-fold increase in chlorophyll content in the lowest compared to the highest light treatment did not change the leaves' light absorption. These results shed new light on photosynthetic and physiological processes, triggering light acclimation in cold temperate eelgrass. Our study documents an MQR value for eelgrass in the St. Lawrence estuary, which is highly pertinent in the context of conservation and restoration of eelgrass meadows.
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Affiliation(s)
- Romy Léger-Daigle
- Québec-Océan and Institut des Sciences de la Mer de Rimouski, Université du Québec à Rimouski, Rimouski, QC, Canada
| | - Fanny Noisette
- Québec-Océan and Institut des Sciences de la Mer de Rimouski, Université du Québec à Rimouski, Rimouski, QC, Canada
| | - Simon Bélanger
- Québec-Océan and Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, QC, Canada
| | - Mathieu Cusson
- Québec-Océan and Département des Sciences Fondamentales, Université du Québec à Chicoutimi, Chicoutimi, QC, Canada
| | - Christian Nozais
- Québec-Océan and Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, QC, Canada
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11
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Katona L, Vadeboncoeur Y, Nietch CT, Hossler K. A Novel Thin-Film Technique to Improve Accuracy of Fluorescence-Based Estimates for Periphytic Biofilms. Water (Basel) 2021; 13:1464. [PMID: 34249375 PMCID: PMC8262624 DOI: 10.3390/w13111464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Recent studies suggest that photophysiological parameters for intact substrates with depth (e.g., periphytic biofilms, microphytobenthos) are overestimated by pulse-amplitude modulated (PAM) fluorometry. This overestimation results from depth-integration effects, following the activation of deeper photosynthesizing layers by an attenuated light signal. To mitigate this error, we propose a novel slide-based thin-film technique in which fluorescence is measured on a vertically representative subsample of the biofilm, spread evenly on a microscope slide. We compared bias and precision for photosynthetic parameters estimated through conventional PAM fluorometry on intact biofilms and through our novel slide-based technique, both theoretically and empirically. Numerical simulations confirmed the consistent overestimation of key parameters for intact biofilms, with relative errors up to 145%, compared to, at most, 52% on thin films. Paired empirical observations likewise demonstrated that estimates based on intact biofilms were consistently higher (up to 248%, p < 0.001) than estimates from thin films. Numerical simulation suggested greater precision with the slide-based technique for homogeneous biofilms, but potentially less precision for heterogeneous biofilms with improper subsampling. Our empirical comparison, however, demonstrated some improvement in precision with the slide-based technique (e.g., the coefficient of variation for the maximum electron transport rate was reduced 30%, p = 0.009). We recommend the use of the slide-based technique, particularly for biofilms that are thick or have small light attenuation coefficients. Care should be taken, however, to obtain vertically representative subsamples of the biofilm for measurement.
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Affiliation(s)
- Leon Katona
- Department of Biological Sciences, Wright State University, 3640 Colonel Glenn Hwy, Dayton, OH 43435, USA
| | - Yvonne Vadeboncoeur
- Department of Biological Sciences, Wright State University, 3640 Colonel Glenn Hwy, Dayton, OH 43435, USA
| | - Christopher T. Nietch
- USEPA Office of Research and Development, Center for Environmental Measurement and Modeling, 26 W Martin Luther King Dr, Cincinnati, OH 45268, USA
| | - Katie Hossler
- Department of Biological Sciences, Wright State University, 3640 Colonel Glenn Hwy, Dayton, OH 43435, USA
- Correspondence:
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12
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Carrara F, Sengupta A, Behrendt L, Vardi A, Stocker R. Bistability in oxidative stress response determines the migration behavior of phytoplankton in turbulence. Proc Natl Acad Sci U S A 2021; 118:e2005944118. [PMID: 33495340 DOI: 10.1073/pnas.2005944118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Turbulence has long been known to drive phytoplankton fitness and species succession: motile species dominate in calmer environments and non-motile species in turbulent conditions. Yet a mechanistic understanding of the effect of turbulence on phytoplankton migratory behavior and physiology is lacking. By combining a method to generate turbulent cues, quantification of stress accumulation and physiology, and a mathematical model of stress dynamics, we show that motile phytoplankton use their mechanical stability to sense the intensity of turbulent cues and integrate these cues in time via stress signaling to trigger switches in migratory behavior. The stress-mediated warning strategy we discovered provides a paradigm for how phytoplankton cope with turbulence, thereby potentially governing which species will be successful in a changing ocean. Turbulence is an important determinant of phytoplankton physiology, often leading to cell stress and damage. Turbulence affects phytoplankton migration both by transporting cells and by triggering switches in migratory behavior, whereby vertically migrating cells can actively invert their direction of migration upon exposure to turbulent cues. However, a mechanistic link between single-cell physiology and vertical migration of phytoplankton in turbulence is currently missing. Here, by combining physiological and behavioral experiments with a mathematical model of stress accumulation and dissipation, we show that the mechanism responsible for the switch in the direction of migration in the marine raphidophyte Heterosigma akashiwo is the integration of reactive oxygen species (ROS) signaling generated by turbulent cues. Within timescales as short as tens of seconds, the emergent downward-migrating subpopulation exhibited a twofold increase in ROS, an indicator of stress, 15% lower photosynthetic efficiency, and 35% lower growth rate over multiple generations compared to the upward-migrating subpopulation. The origin of the behavioral split as a result of a bistable oxidative stress response is corroborated by the observation that exposure of cells to exogenous stressors (H2O2, UV-A radiation, or high irradiance), in lieu of turbulence, caused comparable ROS accumulation and an equivalent split into the two subpopulations. By providing a mechanistic link between the single-cell mechanics of swimming and physiology on the one side and the emergent population-scale migratory response and impact on fitness on the other, the ROS-mediated early warning response we discovered contributes to our understanding of phytoplankton community composition in future ocean conditions.
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13
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Reich HG, Tu WC, Rodriguez IB, Chou Y, Keister EF, Kemp DW, LaJeunesse TC, Ho TY. Iron Availability Modulates the Response of Endosymbiotic Dinoflagellates to Heat Stress. J Phycol 2021; 57:3-13. [PMID: 32996595 DOI: 10.1111/jpy.13078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 06/23/2020] [Revised: 09/03/2020] [Accepted: 09/11/2020] [Indexed: 06/11/2023]
Abstract
Warming and nutrient limitation are stressors known to weaken the health of microalgae. In situations of stress, access to energy reserves can minimize physiological damage. Because of its widespread requirements in biochemical processes, iron is an important trace metal, especially for photosynthetic organisms. Lowered iron availability in oceans experiencing rising temperatures may contribute to the thermal sensitivity of reef-building corals, which rely on mutualisms with dinoflagellates to survive. To test the influence of iron concentration on thermal sensitivity, the physiological responses of cultured symbiotic dinoflagellates (genus Breviolum; family Symbiodiniaceae) were evaluated when exposed to increasing temperatures (26 to 30°C) and iron concentrations ranging from replete (500 pM Fe') to limiting (50 pM Fe') under a diurnal light cycle with saturating radiance. Declines in photosynthetic efficiency at elevated temperatures indicated sensitivity to heat stress. Furthermore, five times the amount of iron was needed to reach exponential growth during heat stress (50 pM Fe' at 26-28°C vs. 250 pM Fe' at 30°C). In treatments where exponential growth was reached, Breviolum psygmophilum grew faster than B.minutum, possibly due to greater cellular contents of iron and other trace metals. The metal composition of B.psygmophilum shifted only at the highest temperature (30°C), whereas changes in B.minutum were observed at lower temperatures (28°C). The influence of iron availability in modulating each alga's response to thermal stress suggests the importance of trace metals to the health of coral-algal mutualisms. Ultimately, a greater ability to acquire scarce metals may improve the tolerance of corals to physiological stressors and contribute to the differences in performance associated with hosting one symbiont species over another.
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Affiliation(s)
- Hannah G Reich
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Wan-Chen Tu
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
| | - Irene B Rodriguez
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
| | - Yalan Chou
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
| | - Elise F Keister
- Department of Biology, The University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Dustin W Kemp
- Department of Biology, The University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Todd C LaJeunesse
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Tung-Yuan Ho
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
- Institute of Oceanography, National Taiwan University, Taipei, Taiwan
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14
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Atkinson J, King NG, Wilmes SB, Moore PJ. Summer and Winter Marine Heatwaves Favor an Invasive Over Native Seaweeds. J Phycol 2020; 56:1591-1600. [PMID: 32679619 DOI: 10.1111/jpy.13051-20-029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 06/23/2020] [Indexed: 05/22/2023]
Abstract
Marine heatwaves (MHWs) are emerging as forceful agents of ecosystem change and are increasing in frequency, duration, and intensity with climate change. During MHWs, physiological thresholds of native species may be exceeded while the performance of invasive species with warm affinities may be enhanced. As a consequence, MHWs could significantly alter an ecosystem's invasive dynamics, but such interactions are poorly understood. Following a 10-d acclimation period, we investigated the physiological resistance and resilience of an intertidal rock pool assemblage invaded by the seaweed Sargassum muticum to realistic 14-d marine heatwave scenarios (+1.5°C, +2.0°C, +3.5°C) followed by a 14-d recovery period. We conducted mesocosm experiments in both summer and winter to investigate temporal variability of MHWs. MHW treatments had clear negative impacts on native seaweeds (Fucus serratus and Chondrus crispus) while enhancing the performance of S. muticum. This pattern was consistent across season indicating that acclimation to cooler ambient temperatures results in winter MHWs having significant impacts on native species. As climate warming advances, this may ultimately lead to changes in competitive interactions and potentially exclusion of native species, while invasive species may proliferate and become more conspicuous within temperate rocky shore environments.
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Affiliation(s)
- James Atkinson
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3DA, UK
| | - Nathan G King
- School of Ocean Sciences, Bangor University, Menai Bridge, LL59 5AB, UK
| | - Sophie B Wilmes
- School of Ocean Sciences, Bangor University, Menai Bridge, LL59 5AB, UK
| | - Pippa J Moore
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3DA, UK
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15
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Atkinson J, King NG, Wilmes SB, Moore PJ. Summer and Winter Marine Heatwaves Favor an Invasive Over Native Seaweeds. J Phycol 2020; 56:1591-1600. [PMID: 32679619 DOI: 10.1111/jpy.13051] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [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: 02/13/2020] [Accepted: 06/23/2020] [Indexed: 06/11/2023]
Abstract
Marine heatwaves (MHWs) are emerging as forceful agents of ecosystem change and are increasing in frequency, duration, and intensity with climate change. During MHWs, physiological thresholds of native species may be exceeded while the performance of invasive species with warm affinities may be enhanced. As a consequence, MHWs could significantly alter an ecosystem's invasive dynamics, but such interactions are poorly understood. Following a 10-d acclimation period, we investigated the physiological resistance and resilience of an intertidal rock pool assemblage invaded by the seaweed Sargassum muticum to realistic 14-d marine heatwave scenarios (+1.5°C, +2.0°C, +3.5°C) followed by a 14-d recovery period. We conducted mesocosm experiments in both summer and winter to investigate temporal variability of MHWs. MHW treatments had clear negative impacts on native seaweeds (Fucus serratus and Chondrus crispus) while enhancing the performance of S. muticum. This pattern was consistent across season indicating that acclimation to cooler ambient temperatures results in winter MHWs having significant impacts on native species. As climate warming advances, this may ultimately lead to changes in competitive interactions and potentially exclusion of native species, while invasive species may proliferate and become more conspicuous within temperate rocky shore environments.
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Affiliation(s)
- James Atkinson
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3DA, UK
| | - Nathan G King
- School of Ocean Sciences, Bangor University, Menai Bridge, LL59 5AB, UK
| | - Sophie B Wilmes
- School of Ocean Sciences, Bangor University, Menai Bridge, LL59 5AB, UK
| | - Pippa J Moore
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, SY23 3DA, UK
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16
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Kennedy F, Martin A, Castrisios K, Cimoli E, McMinn A, Ryan KG. Rapid Manipulation in Irradiance Induces Oxidative Free-Radical Release in a Fast-Ice Algal Community (McMurdo Sound, Antarctica). Front Plant Sci 2020; 11:588005. [PMID: 33324435 PMCID: PMC7723870 DOI: 10.3389/fpls.2020.588005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/04/2020] [Indexed: 06/12/2023]
Abstract
Sea ice supports a unique assemblage of microorganisms that underpin Antarctic coastal food-webs, but reduced ice thickness coupled with increased snow cover will modify energy flow and could lead to photodamage in ice-associated microalgae. In this study, microsensors were used to examine the influence of rapid shifts in irradiance on extracellular oxidative free radicals produced by sea-ice algae. Bottom-ice algal communities were exposed to one of three levels of incident light for 10 days: low (0.5 μmol photons m-2 s-1, 30 cm snow cover), mid-range (5 μmol photons m-2 s-1, 10 cm snow), or high light (13 μmol photons m-2 s-1, no snow). After 10 days, the snow cover was reversed (either removed or added), resulting in a rapid change in irradiance at the ice-water interface. In treatments acclimated to low light, the subsequent exposure to high irradiance resulted in a ~400× increase in the production of hydrogen peroxide (H2O2) and a 10× increase in nitric oxide (NO) concentration after 24 h. The observed increase in oxidative free radicals also resulted in significant changes in photosynthetic electron flow, RNA-oxidative damage, and community structural dynamics. In contrast, there was no significant response in sea-ice algae acclimated to high light and then exposed to a significantly lower irradiance at either 24 or 72 h. Our results demonstrate that microsensors can be used to track real-time in-situ stress in sea-ice microbial communities. Extrapolating to ecologically relevant spatiotemporal scales remains a significant challenge, but this approach offers a fundamentally enhanced level of resolution for quantifying the microbial response to global change.
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Affiliation(s)
- Fraser Kennedy
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | - Andrew Martin
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | - Katerina Castrisios
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | - Emiliano Cimoli
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
- Geography and Spatial Sciences, School of Technology, Hobart, TAS, Australia
| | - Andrew McMinn
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | - Ken G. Ryan
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
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17
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Williamson CJ, Cook J, Tedstone A, Yallop M, McCutcheon J, Poniecka E, Campbell D, Irvine-Fynn T, McQuaid J, Tranter M, Perkins R, Anesio A. Algal photophysiology drives darkening and melt of the Greenland Ice Sheet. Proc Natl Acad Sci U S A 2020; 117:5694-705. [PMID: 32094168 DOI: 10.1073/pnas.1918412117] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Processes that darken the surface of the Greenland Ice Sheet (GrIS) enhance energy absorption and accelerate melt, with consequences for global sea-level rise. Here, we demonstrate how summer blooms of “glacier algae” darken the ice surface, significantly impacting the physical integrity of the environment. We identify and quantify the energy regulation mechanisms employed by glacier algae to balance their requirements for photosynthesis and growth with the extreme light and temperature regime of the GrIS, demonstrating how these mechanisms are optimized to darken and melt the ice surface. Our findings are critical for the incorporation of biological feedbacks into predictive models of GrIS surface runoff and provide unique insight into how photoautotrophic life excels within icy environments. Blooms of Zygnematophycean “glacier algae” lower the bare ice albedo of the Greenland Ice Sheet (GrIS), amplifying summer energy absorption at the ice surface and enhancing meltwater runoff from the largest cryospheric contributor to contemporary sea-level rise. Here, we provide a step change in current understanding of algal-driven ice sheet darkening through quantification of the photophysiological mechanisms that allow glacier algae to thrive on and darken the bare ice surface. Significant secondary phenolic pigmentation (11 times the cellular content of chlorophyll a) enables glacier algae to tolerate extreme irradiance (up to ∼4,000 µmol photons⋅m−2⋅s−1) while simultaneously repurposing captured ultraviolet and short-wave radiation for melt generation. Total cellular energy absorption is increased 50-fold by phenolic pigmentation, while glacier algal chloroplasts positioned beneath shading pigments remain low-light–adapted (Ek ∼46 µmol photons⋅m−2⋅s−1) and dependent upon typical nonphotochemical quenching mechanisms for photoregulation. On the GrIS, glacier algae direct only ∼1 to 2.4% of incident energy to photochemistry versus 48 to 65% to ice surface melting, contributing an additional ∼1.86 cm water equivalent surface melt per day in patches of high algal abundance (∼104 cells⋅mL−1). At the regional scale, surface darkening is driven by the direct and indirect impacts of glacier algae on ice albedo, with a significant negative relationship between broadband albedo (Moderate Resolution Imaging Spectroradiometer [MODIS]) and glacier algal biomass (R2 = 0.75, n = 149), indicating that up to 75% of the variability in albedo across the southwestern GrIS may be attributable to the presence of glacier algae.
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18
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McCoy SJ, Santillán-Sarmiento A, Brown MT, Widdicombe S, Wheeler GL. Photosynthetic Responses of Turf-forming Red Macroalgae to High CO 2 Conditions. J Phycol 2020; 56:85-96. [PMID: 31553063 DOI: 10.1111/jpy.12922] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 02/12/2019] [Accepted: 08/18/2019] [Indexed: 06/10/2023]
Abstract
Seaweeds are important components of near-shore ecosystems as primary producers, foundation species, and biogeochemical engineers. Seaweed communities are likely to alter under predicted climate change scenarios. We tested the physiological responses of three perennial, turf-building, intertidal rhodophytes, Mastocarpus stellatus, Osmundea pinnatifida, and the calcified Ellisolandia elongata, to elevated pCO2 over 6 weeks. Responses varied between these three species. E. elongata was strongly affected by high pCO2 , whereas non-calcified species were not. Elevated pCO2 did not induce consistent responses of photosynthesis and respiration across these three species. While baseline photophysiology differed significantly between species, we found few clear effects of elevated pCO2 on this aspect of macroalgal physiology. We found effects of within-species variation in elevated pCO2 response in M. stellatus, but not in the other species. Overall, our data confirm the sensitivity of calcified macroalgae to elevated pCO2 , but we found no evidence suggesting that elevated pCO2 conditions will have a strong positive or negative impact on photosynthetic parameters in non-calcified macroalgae.
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Affiliation(s)
- Sophie J McCoy
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, Florida, 32306-4295, USA
- Plymouth Marine Laboratory, Prospect Place, Plymouth, Devon, PL1 3DH, UK
| | - Alex Santillán-Sarmiento
- School of Biological and Marine Sciences, University of Plymouth, 4th Floor Davy Building, Drake Circus, Plymouth, PL4 8AA, UK
- Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121, Napoli, Italy
- Faculty of Engineering, National University of Chimborazo, Av. Antonio José de Sucre Km 1 1/2 via Guano, EC 060108, Riobamba, Ecuador
| | - Murray T Brown
- School of Biological and Marine Sciences, University of Plymouth, 4th Floor Davy Building, Drake Circus, Plymouth, PL4 8AA, UK
| | - Stephen Widdicombe
- Plymouth Marine Laboratory, Prospect Place, Plymouth, Devon, PL1 3DH, UK
| | - Glen L Wheeler
- Marine Biological Association of the UK, Citadel Hill, Plymouth, PL1 2PB, UK
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19
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Viana IG, Moreira-Saporiti A, Teichberg M. Species-Specific Trait Responses of Three Tropical Seagrasses to Multiple Stressors: The Case of Increasing Temperature and Nutrient Enrichment. Front Plant Sci 2020; 11:571363. [PMID: 33224162 PMCID: PMC7674176 DOI: 10.3389/fpls.2020.571363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 10/12/2020] [Indexed: 05/05/2023]
Abstract
Seagrass meadows are declining globally. The decrease of seagrass area is influenced by the simultaneous occurrence of many factors at the local and global scale, including nutrient enrichment and climate change. This study aims to find out how increasing temperature and nutrient enrichment affect the morphological, biochemical and physiological responses of three coexisting tropical species, Thalassia hemprichii, Cymodocea serrulata and Halophila stipulacea. To achieve these aims, a 1-month experiment under laboratory conditions combining two temperature (maximum ambient temperature and current average temperature) and two nutrient (high and low N and P concentrations) treatments was conducted. The results showed that the seagrasses were differentially affected by all treatments depending on their life-history strategies. Under higher temperature treatments, C. serrulata showed photo-acclimation strategies, while T. hemprichii showed decreased photo-physiological performance. In contrast, T. hemprichii was resistant to nutrient over-enrichment, showing enhanced nutrient content and physiological changes, but C. serrulata suffered BG nutrient loss. The limited response of H. stipulacea to nutrient enrichment or high temperature suggests that this seagrass is a tolerant species that may have a dormancy state with lower photosynthetic performance and smaller-size individuals. Interaction between both factors was limited and generally showed antagonistic effects only on morphological and biochemical traits, but not on physiological traits. These results highlight the different effects and strategies co-inhabiting seagrasses have in response to environmental changes, showing winners and losers of a climate change scenario that may eventually cause biodiversity loss. Trait responses to these stressors could potentially make the seagrasses weaker to cope with following events, due to BG biomass or nutrient loss. This is of importance as biodiversity loss in tropical seagrass ecosystems could change the overall effectiveness of ecosystem functions and services provided by the seagrass meadows.
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Affiliation(s)
- Inés G. Viana
- Department of Ecology and Animal Biology, University of Vigo, Vigo, Spain
- Leibniz Centre for Tropical Marine Research GmbH, Bremen, Germany
- *Correspondence: Inés G. Viana, ;
| | - Agustín Moreira-Saporiti
- Leibniz Centre for Tropical Marine Research GmbH, Bremen, Germany
- Faculty of Biology and Chemistry, University of Bremen, Bremen, Germany
| | - Mirta Teichberg
- Leibniz Centre for Tropical Marine Research GmbH, Bremen, Germany
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20
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Plummer S, Taylor AE, Harvey EL, Hansel CM, Diaz JM. Dynamic Regulation of Extracellular Superoxide Production by the Coccolithophore Emiliania huxleyi (CCMP 374). Front Microbiol 2019; 10:1546. [PMID: 31354655 PMCID: PMC6640029 DOI: 10.3389/fmicb.2019.01546] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 06/20/2019] [Indexed: 11/13/2022] Open
Abstract
In marine waters, ubiquitous reactive oxygen species (ROS) drive biogeochemical cycling of metals and carbon. Marine phytoplankton produce the ROS superoxide (O2−) extracellularly and can be a dominant source of O2− in natural aquatic systems. However, the cellular regulation, biological functioning, and broader ecological impacts of extracellular O2− production by marine phytoplankton remain mysterious. Here, we explored the regulation and potential roles of extracellular O2− production by a noncalcifying strain of the cosmopolitan coccolithophorid Emiliania huxleyi, a key species of marine phytoplankton that has not been examined for extracellular O2− production previously. Cell-normalized extracellular O2− production was the highest under presumably low-stress conditions during active proliferation and inversely related to cell density during exponential growth phase. Removal of extracellular O2− through addition of the O2− scavenger superoxide dismutase (SOD), however, increased growth rates, growth yields, cell biovolume, and photosynthetic efficiency (Fv/Fm) indicating an overall physiological improvement. Thus, the presence of extracellular O2− does not directly stimulate E. huxleyi proliferation, as previously suggested for other phytoplankton, bacteria, fungi, and protists. Extracellular O2− production decreased in the dark, suggesting a connection with photosynthetic processes. Taken together, the tight regulation of this stress independent production of extracellular O2− by E. huxleyi suggests that it could be involved in fundamental photophysiological processes.
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Affiliation(s)
- Sydney Plummer
- Department of Marine Sciences, Skidaway Institute of Oceanography, University of Georgia, Savannah, GA, United States
| | - Alexander E Taylor
- Department of Chemistry, University of Vermont, Burlington, VT, United States
| | - Elizabeth L Harvey
- Department of Marine Sciences, Skidaway Institute of Oceanography, University of Georgia, Savannah, GA, United States
| | - Colleen M Hansel
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
| | - Julia M Diaz
- Department of Marine Sciences, Skidaway Institute of Oceanography, University of Georgia, Savannah, GA, United States
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Chrismas NAM, Williamson CJ, Yallop ML, Anesio AM, Sánchez-Baracaldo P. Photoecology of the Antarctic cyanobacterium Leptolyngbya sp. BC1307 brought to light through community analysis, comparative genomics and in vitro photophysiology. Mol Ecol 2019; 27:5279-5293. [PMID: 30565777 DOI: 10.1111/mec.14953] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [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: 04/24/2018] [Accepted: 10/11/2018] [Indexed: 12/17/2022]
Abstract
Cyanobacteria are important photoautotrophs in extreme environments such as the McMurdo Dry Valleys, Antarctica. Terrestrial Antarctic cyanobacteria experience constant darkness during the winter and constant light during the summer which influences the ability of these organisms to fix carbon over the course of an annual cycle. Here, we present a unique approach combining community structure, genomic and photophysiological analyses to understand adaptation to Antarctic light regimes in the cyanobacterium Leptolyngbya sp. BC1307. We show that Leptolyngbya sp. BC1307 belongs to a clade of cyanobacteria that inhabits near-surface environments in the McMurdo Dry Valleys. Genomic analyses reveal that, unlike close relatives, Leptolyngbya sp. BC1307 lacks the genes necessary for production of the pigment phycoerythrin and is incapable of complimentary chromatic acclimation, while containing several genes responsible for known photoprotective pigments. Photophysiology experiments confirmed Leptolyngbya sp. BC1307 to be tolerant of short-term exposure to high levels of photosynthetically active radiation, while sustained exposure reduced its capacity for photoprotection. As such, Leptolyngbya sp. BC1307 likely exploits low-light microenvironments within cyanobacterial mats in the McMurdo Dry Valleys.
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Affiliation(s)
- Nathan A M Chrismas
- Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, UK.,School of Geographical Sciences, University of Bristol, Bristol, UK
| | - Christopher J Williamson
- School of Geographical Sciences, University of Bristol, Bristol, UK.,School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol, UK
| | - Marian L Yallop
- School of Biological Sciences, Life Sciences Building, University of Bristol, Bristol, UK
| | - Alexandre M Anesio
- School of Geographical Sciences, University of Bristol, Bristol, UK.,Department of Environmental Sciences, Aarhus University, Roskilde, Denmark
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22
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Tóth VR, Villa P, Pinardi M, Bresciani M. Aspects of Invasiveness of Ludwigia and Nelumbo in Shallow Temperate Fluvial Lakes. Front Plant Sci 2019; 10:647. [PMID: 31156691 PMCID: PMC6531864 DOI: 10.3389/fpls.2019.00647] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/29/2019] [Indexed: 06/09/2023]
Abstract
The relationship between invasive plant functional traits and their invasiveness is still the subject of scientific investigation, and the backgrounds of transition from non-native to invasive species in ecosystems are therefore poorly understood. Furthermore, our current knowledge on species invasiveness is heavily biased toward terrestrial species; we know much less about the influence of allochthonous plant traits on their invasiveness in aquatic ecosystems. In this paper, we present the results of a study on physiological and ecological traits of two introduced and three native macrophyte species in the Mantua lakes system (northern Italy). We compared their photophysiology, pigment content, leaf reflectance, and phenology in order to assess how the invasive Nelumbo nucifera and Ludwigia hexapetala perform compared to native species, Nuphar lutea, Nymphaea alba, and Trapa natans. We found L. hexapetala to have higher photosynthetic efficiency and to tolerate higher light intensities than N. nucifera and the native species especially at extreme weather conditions (prolonged exposure to high light and higher temperatures). Chlorophyll a and b, and carotenoids content of both allochthonous species were substantially higher than those of native plants, suggesting adaptive response to the ecosystem of Mantua lakes system. Higher variability of recorded data in invasive species was also observed. These observations suggest advanced photosynthetic efficiency of the invasive species, especially L. hexapetala, resulting in faster growth rates and higher productivity. This was supported by the evaluation of seasonal dynamics mapped from satellite remote sensing data. This study provides empirical evidence for the relationship between specific plant physiological traits and invasiveness of aquatic plant species, highlighting the importance of trait studies in predicting ecosystem-level impacts of invasive plant species.
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Affiliation(s)
- Viktor R. Tóth
- Balaton Limnological Institute, MTA Centre for Ecological Research, Hungarian Academy of Sciences, Tihany, Hungary
| | - Paolo Villa
- Institute for Electromagnetic Sensing of the Environment, National Research Council, Milan, Italy
| | - Monica Pinardi
- Institute for Electromagnetic Sensing of the Environment, National Research Council, Milan, Italy
| | - Mariano Bresciani
- Institute for Electromagnetic Sensing of the Environment, National Research Council, Milan, Italy
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23
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Kulk G, Buist A, van de Poll WH, Rozema PD, Buma AGJ. Size scaling of photophysiology and growth in four freshly isolated diatom species from Ryder Bay, western Antarctic peninsula. J Phycol 2019; 55:314-328. [PMID: 30449029 PMCID: PMC6590143 DOI: 10.1111/jpy.12813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 10/19/2018] [Indexed: 06/09/2023]
Abstract
Diatoms are one of the dominant groups in phytoplankton communities of the western Antarctic Peninsula (WAP). Although generally well-studied, little is known about size dependent photophysiological responses in diatom bloom formation and succession. To increase this understanding, four Antarctic diatom species covering two orders of magnitude in cell size were isolated in northern Marguerite Bay (WAP). Fragilariopsis sp., Pseudo-nitzschia cf. subcurvata, Thalassiosira cf. antarctica, and Proboscia cf. alata were acclimated to three different irradiances after which photophysiology, electron transport, carbon fixation, and growth were assessed. The small species Fragilariopsis sp., Pseudo-nitzschia cf. subcurvata, and large species Proboscia cf. alata showed similar photoacclimation to higher irradiances with a decrease in cellular chlorophyll a and an increase in chlorophyll a specific absorption and xanthophyll cycle pigments and activity. In contrast, pigment concentrations and absorption remained unaffected by higher irradiances in the large species Thalassiosira cf. antarctica. Overall, the small species showed significantly higher growth rates compared to the large species, which was related to relatively high light harvesting capacity and electron transport rates in the smaller species. However, photophysiological responses related to photoinhibition and photoprotection and carbon fixation showed no relationship with cell size. This study supports the dominance of small diatoms at low irradiances during winter and early spring, but does not provide photophysiological evidence for the dominance of large diatoms during the phytoplankton bloom in the WAP. This suggests that other factors such as grazing and nutrient availability are likely to play a major role in diatom bloom formation.
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Affiliation(s)
- Gemma Kulk
- Department of Ocean EcosystemsEnergy and Sustainability Research Institute GroningenUniversity of GroningenNijenborgh 79747 AGGroningenthe Netherlands
| | - Anton Buist
- Department of Ocean EcosystemsEnergy and Sustainability Research Institute GroningenUniversity of GroningenNijenborgh 79747 AGGroningenthe Netherlands
| | - Willem H. van de Poll
- Department of Ocean EcosystemsEnergy and Sustainability Research Institute GroningenUniversity of GroningenNijenborgh 79747 AGGroningenthe Netherlands
| | - Patrick D. Rozema
- Department of Ocean EcosystemsEnergy and Sustainability Research Institute GroningenUniversity of GroningenNijenborgh 79747 AGGroningenthe Netherlands
| | - Anita G. J. Buma
- Department of Ocean EcosystemsEnergy and Sustainability Research Institute GroningenUniversity of GroningenNijenborgh 79747 AGGroningenthe Netherlands
- Arctic CentreFaculty of ArtsUniversity of GroningenAweg 309718 CWGroningenthe Netherlands
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24
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Heiden JP, Thoms S, Bischof K, Trimborn S, Raven J. Ocean acidification stimulates particulate organic carbon accumulation in two Antarctic diatom species under moderate and high natural solar radiation. J Phycol 2018; 54:505-517. [PMID: 29791031 PMCID: PMC6120492 DOI: 10.1111/jpy.12753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 04/24/2018] [Indexed: 06/08/2023]
Abstract
Impacts of rising atmospheric CO2 concentrations and increased daily irradiances from enhanced surface water stratification on phytoplankton physiology in the coastal Southern Ocean remain still unclear. Therefore, in the two Antarctic diatoms Fragilariopsis curta and Odontella weissflogii, the effects of moderate and high natural solar radiation combined with either ambient or future pCO2 on cellular particulate organic carbon (POC) contents and photophysiology were investigated. Results showed that increasing CO2 concentrations had greater impacts on diatom physiology than exposure to increasing solar radiation. Irrespective of the applied solar radiation regime, cellular POC quotas increased with future pCO2 in both diatoms. Lowered maximum quantum yields of photochemistry in PSII (Fv /Fm ) indicated a higher photosensitivity under these conditions, being counteracted by increased cellular concentrations of functional photosynthetic reaction centers. Overall, our results suggest that both bloom-forming Antarctic coastal diatoms might increase carbon contents under future pCO2 conditions despite reduced physiological fitness. This indicates a higher potential for primary productivity by the two diatom species with important implications for the CO2 sequestration potential of diatom communities in the future coastal Southern Ocean.
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Affiliation(s)
- Jasmin P. Heiden
- Alfred Wegener Institute Helmholtz Center for Polar and Marine ResearchAm Handelshafen 1227570BremerhavenGermany
- Marine BotanyUniversity BremenLeobener Str. NW228359BremenGermany
| | - Silke Thoms
- Alfred Wegener Institute Helmholtz Center for Polar and Marine ResearchAm Handelshafen 1227568BremerhavenGermany
| | - Kai Bischof
- Marine BotanyUniversity BremenLeobener Str. NW228359BremenGermany
| | - Scarlett Trimborn
- Alfred Wegener Institute Helmholtz Center for Polar and Marine ResearchAm Handelshafen 1227570BremerhavenGermany
- Marine BotanyUniversity BremenLeobener Str. NW228359BremenGermany
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25
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Tait LW, Hawes I, Schiel DR. Integration of chlorophyll a fluorescence and photorespirometry techniques to understand production dynamics in macroaglal communities. J Phycol 2017; 53:476-485. [PMID: 28207158 DOI: 10.1111/jpy.12524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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: 09/12/2016] [Accepted: 11/26/2016] [Indexed: 06/06/2023]
Abstract
Global declines of macroalgal beds in coastal waters have prompted a plethora of studies attempting to understand the drivers of change within dynamic nearshore ecosystems. Photosynthetic measurements are good tools for assessing the consequences of numerous stressors of macroalgae, but there is somewhat of a disconnection between studies that focus on organism-specific ecophysiological responses and those that address causes and consequences of shifts in macroalgal productivity. Our goal is to highlight the applications of two complementary tools for measuring photosynthesis-variable chlorophyll a fluorescence and photorespirometry-and provide guidance for the integration of physiology and ecology to understand the drivers of change in macroalgal communities. Photorespirometry can provide an integrated measure of whole-community metabolism, including an estimate of the physiological costs associated with stressors, while fluorescence-based techniques provide point measures of the efficiency of the photosynthetic apparatus within communities. Variable chlorophyll a fluorescence does not provide an estimate of carbon balance or integrated photosynthesis across either whole plants or whole communities but can be used to estimate the contribution of individual community components in the dynamic subcanopy environment to help us understand the mechanisms underlying observed responses. We highlight the importance of the highly dynamic light environment within macroalgal communities and call for better integration of physiological techniques in an ecological context to enhance our understanding of the responses of whole communities to local and global stressors.
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Affiliation(s)
- Leigh W Tait
- National Institute of Water & Atmosphere, 10 Kyle St, Riccarton 8011, Christchurch, New Zealand
- Marine Ecology Research Group, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
| | - Ian Hawes
- Coastal Marine Field Station, University of Waikato, Tauranga, 3110, New Zealand
| | - David R Schiel
- Marine Ecology Research Group, School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
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26
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McIlroy SE, Gillette P, Cunning R, Klueter A, Capo T, Baker AC, Coffroth MA. The effects of Symbiodinium (Pyrrhophyta) identity on growth, survivorship, and thermal tolerance of newly settled coral recruits. J Phycol 2016; 52:1114-1124. [PMID: 27690269 DOI: 10.1111/jpy.12471] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [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: 03/11/2016] [Accepted: 08/23/2016] [Indexed: 05/23/2023]
Abstract
For many coral species, the obligate association with phylogenetically diverse algal endosymbiont species is dynamic in time and space. Here, we used controlled laboratory inoculations of newly settled, aposymbiotic corals (Orbicella faveolata) with two cultured species of algal symbiont (Symbiodinium microadriaticum and S. minutum) to examine the role of symbiont identity on growth, survivorship, and thermal tolerance of the coral holobiont. We evaluated these data in the context of Symbiodinium photophysiology for 9 months post-settlement and also during a 5-d period of elevated temperatures Our data show that recruits that were inoculated with S. minutum grew significantly slower than those inoculated with S. microadriaticum (occasionally co-occurring with S. minutum), but that there was no difference in survivorship of O. faveolata polyps infected with Symbiodinium. However, photophysiological metrics (∆Fv/F'm, the efficiency with which available light is used to drive photosynthesis and α, the maximum light utilization coefficient) were higher in those slower growing recruits containing S. minutum. These findings suggest that light use (i.e., photophysiology) and carbon acquisition by the coral host (i.e., host growth) are decoupled, but did not distinguish the source of this difference. Neither Symbiodinium treatment demonstrated a significant negative effect of a 5-d exposure to temperatures as high as 32°C under low light conditions similar to those measured at settlement habitats.
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Affiliation(s)
- Shelby E McIlroy
- Graduate Program in Evolution, Ecology, and Behavior, University at Buffalo, 126 Cooke Hall, Buffalo, New York, 14260, USA
| | - Phillip Gillette
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Csy, Miami, Florida, 33149, USA
| | - Ross Cunning
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Csy, Miami, Florida, 33149, USA
| | - Anke Klueter
- Department of Geology, University at Buffalo, 126 Cooke Hall, Buffalo, New York, 14260, USA
| | - Tom Capo
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Csy, Miami, Florida, 33149, USA
| | - Andrew C Baker
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Csy, Miami, Florida, 33149, USA
| | - Mary Alice Coffroth
- Graduate Program in Evolution, Ecology, and Behavior, University at Buffalo, 126 Cooke Hall, Buffalo, New York, 14260, USA
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27
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Bagshaw EA, Wadham JL, Tranter M, Perkins R, Morgan A, Williamson CJ, Fountain AG, Fitzsimons S, Dubnick A. Response of Antarctic cryoconite microbial communities to light. FEMS Microbiol Ecol 2016; 92:fiw076. [PMID: 27095815 PMCID: PMC4864406 DOI: 10.1093/femsec/fiw076] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/10/2016] [Indexed: 11/28/2022] Open
Abstract
Microbial communities on polar glacier surfaces are found dispersed on the ice surface, or concentrated in cryoconite holes and cryolakes, which are accumulations of debris covered by a layer of ice for some or all of the year. The ice lid limits the penetration of photosynthetically available radiation (PAR) to the sediment layer, since the ice attenuates up to 99% of incoming radiation. This suite of field and laboratory experiments demonstrates that PAR is an important control on primary production in cryoconite and cryolake ecosystems. Increased light intensity increased efficiency of primary production in controlled laboratory incubations of debris from the surface of Joyce Glacier, McMurdo Dry Valleys, Antarctica. However, when light intensity was increased to levels near that received on the ice surface, without the protection of an ice lid, efficiency decreased and measurements of photophysiology showed that the communities suffered light stress. The communities are therefore well adapted to low light levels. Comparison with Arctic cryoconite communities, which are typically not covered by an ice lid for the majority of the ablation season, showed that these organisms were also stressed by high light, so they must employ strategies to protect against photodamage. Microbial communities in cryoconite holes and cryolakes on glaciers in Antarctica are adapted to low light levels and exhibit stress when exposed to high light.
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Affiliation(s)
- Elizabeth A Bagshaw
- School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK
| | - Jemma L Wadham
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, BS8 1SS, UK
| | - Martyn Tranter
- Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, BS8 1SS, UK
| | - Rupert Perkins
- School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK
| | - Alistair Morgan
- School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK
| | - Christopher J Williamson
- School of Earth and Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, BS8 1SS, UK
| | - Andrew G Fountain
- Departments of Geology and Geography, Portland State University, Portland, Oregon OR 97201, USA
| | - Sean Fitzsimons
- Department of Geography, University of Otago, Dunedin, PO Box 56, New Zealand
| | - Ashley Dubnick
- Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, TG6 2E3, Canada
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28
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Hoppe CJM, Holtz L, Trimborn S, Rost B. Ocean acidification decreases the light-use efficiency in an Antarctic diatom under dynamic but not constant light. New Phytol 2015; 207:159-171. [PMID: 25708812 PMCID: PMC4950296 DOI: 10.1111/nph.13334] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 01/12/2015] [Indexed: 05/07/2023]
Abstract
There is increasing evidence that different light intensities strongly modulate the effects of ocean acidification (OA) on marine phytoplankton. The aim of the present study was to investigate interactive effects of OA and dynamic light, mimicking natural mixing regimes. The Antarctic diatom Chaetoceros debilis was grown under two pCO2 (390 and 1000 μatm) and light conditions (constant and dynamic), the latter yielding the same integrated irradiance over the day. To characterize interactive effects between treatments, growth, elemental composition, primary production and photophysiology were investigated. Dynamic light reduced growth and strongly altered the effects of OA on primary production, being unaffected by elevated pCO2 under constant light, yet significantly reduced under dynamic light. Interactive effects between OA and light were also observed for Chl production and particulate organic carbon quotas. Response patterns can be explained by changes in the cellular energetic balance. While the energy transfer efficiency from photochemistry to biomass production (Φe,C ) was not affected by OA under constant light, it was drastically reduced under dynamic light. Contrasting responses under different light conditions need to be considered when making predictions regarding a more stratified and acidified future ocean.
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Affiliation(s)
- Clara J. M. Hoppe
- Alfred Wegener Institute – Helmholtz Centre for Polar and Marine ResearchAm Handelshafen 12Bremerhaven27570Germany
| | - Lena‐Maria Holtz
- Alfred Wegener Institute – Helmholtz Centre for Polar and Marine ResearchAm Handelshafen 12Bremerhaven27570Germany
| | - Scarlett Trimborn
- Alfred Wegener Institute – Helmholtz Centre for Polar and Marine ResearchAm Handelshafen 12Bremerhaven27570Germany
- University BremenLeobener Straße NW2‐ABremen28359Germany
| | - Björn Rost
- Alfred Wegener Institute – Helmholtz Centre for Polar and Marine ResearchAm Handelshafen 12Bremerhaven27570Germany
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29
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Abstract
Coral reef ecosystems thrive in tropical oligotrophic oceans because of the relationship between corals and endosymbiotic dinoflagellate algae called Symbiodinium. Symbiodinium convert sunlight and carbon dioxide into organic carbon and oxygen to fuel coral growth and calcification, creating habitat for these diverse and productive ecosystems. Light is thus a key regulating factor shaping the productivity, physiology, and ecology of the coral holobiont. Similar to all oxygenic photoautotrophs, Symbiodinium must safely harvest sunlight for photosynthesis and dissipate excess energy to prevent oxidative stress. Oxidative stress is caused by environmental stressors such as those associated with global climate change, and ultimately leads to breakdown of the coral-algal symbiosis known as coral bleaching. Recently, large-scale coral bleaching events have become pervasive and frequent threatening and endangering coral reefs. Because the coral-algal symbiosis is the biological engine producing the reef, the future of coral reef ecosystems depends on the ecophysiology of the symbiosis. This review examines the photobiology of the coral-algal symbiosis with particular focus on the photophysiological responses and timescales of corals and Symbiodinium. Additionally, this review summarizes the light environment and its dynamics, the vulnerability of the symbiosis to oxidative stress, the abiotic and biotic factors influencing photosynthesis, the diversity of the coral-algal symbiosis, and recent advances in the field. Studies integrating physiology with the developing "omics" fields will provide new insights into the coral-algal symbiosis. Greater physiological and ecological understanding of the coral-algal symbiosis is needed for protection and conservation of coral reefs.
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Affiliation(s)
- Melissa S. Roth
- Department of Plant and Microbial Biology, University of California BerkeleyBerkeley, CA, USA
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30
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Dimond JL, Bingham BL, le Muller-Parker G, Oakley CA. Symbiont physiology and population dynamics before and during symbiont shifts in a flexible algal-cnidarian symbiosis. J Phycol 2013; 49:1074-1083. [PMID: 27007628 DOI: 10.1111/jpy.12112] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 08/05/2013] [Indexed: 06/05/2023]
Abstract
For cnidarians that can undergo shifts in algal symbiont relative abundance, the underlying algal physiological changes that accompany these shifts are not well known. The sea anemone Anthopleura elegantissima associates with the dinoflagellate Symbiodinium muscatinei and the chlorophyte Elliptochloris marina, symbionts with very different tolerances to light and temperature. We compared the performance of these symbionts in anemones maintained in an 8-11.5 month outdoor common garden experiment with simulated intertidal conditions and three levels of shading (2, 43, and 85% ambient irradiance). Symbiont densities, mitotic indices, photophysiology and pigments were assessed at three time points during the summer, a period of high irradiance and solar heating during aerial exposure. Whereas S. muscatinei was either neutrally or positively affected by higher irradiance treatments, E. marina responded mostly negatively to high irradiance. E. marina in the 85% irradiance treatment exhibited significantly reduced Pmax and chlorophyll early in the summer, but it was not until nearly 3 months later that a shift in symbiont relative abundance toward S. muscatinei occurred, coincident with bleaching. Symbiont densities and proportions remained largely stable in all other treatments over time, and displacement of S. muscatinei by E. marina was not observed in the 2% irradiance treatment despite the potentially better performance of E. marina. While our results support the view that rapid changes in symbiont relative abundance are typically associated with symbiont physiological dysfunction and bleaching, they also show that significant temporal lags may occur between the onset of symbiont stress and shifts in symbiont relative abundances.
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Affiliation(s)
- James L Dimond
- Shannon Point Marine Center, Western Washington University, 1900 Shannon Point Rd., Anacortes, Washington, 98221, USA
| | - Brian L Bingham
- Department of Environmental Sciences, Western Washington University, 516 High St., Bellingham, Washington, 98225, USA
| | - Gisè le Muller-Parker
- Division of Graduate Education, National Science Foundation, Arlington, Virginia, 22230, USA
| | - Clinton A Oakley
- Department of Plant Biology, University of Georgia, Athens, Georgia, 30602, USA
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31
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Mella-Flores D, Six C, Ratin M, Partensky F, Boutte C, Le Corguillé G, Marie D, Blot N, Gourvil P, Kolowrat C, Garczarek L. Prochlorococcus and Synechococcus have Evolved Different Adaptive Mechanisms to Cope with Light and UV Stress. Front Microbiol 2012; 3:285. [PMID: 23024637 PMCID: PMC3441193 DOI: 10.3389/fmicb.2012.00285] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 07/19/2012] [Indexed: 11/13/2022] Open
Abstract
Prochlorococcus and Synechococcus, which numerically dominate vast oceanic areas, are the two most abundant oxygenic phototrophs on Earth. Although they require solar energy for photosynthesis, excess light and associated high UV radiations can induce high levels of oxidative stress that may have deleterious effects on their growth and productivity. Here, we compared the photophysiologies of the model strains Prochlorococcus marinus PCC 9511 and Synechococcus sp. WH7803 grown under a bell-shaped light/dark cycle of high visible light supplemented or not with UV. Prochlorococcus exhibited a higher sensitivity to photoinactivation than Synechococcus under both conditions, as shown by a larger drop of photosystem II (PSII) quantum yield at noon and different diel patterns of the D1 protein pool. In the presence of UV, the PSII repair rate was significantly depressed at noon in Prochlorococcus compared to Synechococcus. Additionally, Prochlorococcus was more sensitive than Synechococcus to oxidative stress, as shown by the different degrees of PSII photoinactivation after addition of hydrogen peroxide. A transcriptional analysis also revealed dramatic discrepancies between the two organisms in the diel expression patterns of several genes involved notably in the biosynthesis and/or repair of photosystems, light-harvesting complexes, CO(2) fixation as well as protection mechanisms against light, UV, and oxidative stress, which likely translate profound differences in their light-controlled regulation. Altogether our results suggest that while Synechococcus has developed efficient ways to cope with light and UV stress, Prochlorococcus cells seemingly survive stressful hours of the day by launching a minimal set of protection mechanisms and by temporarily bringing down several key metabolic processes. This study provides unprecedented insights into understanding the distinct depth distributions and dynamics of these two picocyanobacteria in the field.
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Affiliation(s)
- Daniella Mella-Flores
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- Groupe Plancton Océanique, CNRS, UMR 7144Roscoff, France
- Departamento de Ecología, Facultad de Ciencias Biologicas, Pontificia Universidad Catolica de ChileSantiago, Chile
| | - Christophe Six
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- Groupe Plancton Océanique, CNRS, UMR 7144Roscoff, France
| | - Morgane Ratin
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- Groupe Plancton Océanique, CNRS, UMR 7144Roscoff, France
| | - Frédéric Partensky
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- Groupe Plancton Océanique, CNRS, UMR 7144Roscoff, France
| | - Christophe Boutte
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- Groupe Plancton Océanique, CNRS, UMR 7144Roscoff, France
| | - Gildas Le Corguillé
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- CNRS, FR 2424, Service Informatique et GénomiqueRoscoff, France
| | - Dominique Marie
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- Groupe Plancton Océanique, CNRS, UMR 7144Roscoff, France
| | - Nicolas Blot
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- Groupe Plancton Océanique, CNRS, UMR 7144Roscoff, France
- Laboratoire Microorganismes: Génome et Environnement, Clermont Université, Université Blaise PascalClermont-Ferrand, France
- Laboratoire Microorganismes: Génome et Environnement, CNRS, UMR 6023Aubière, France
| | - Priscillia Gourvil
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- Groupe Plancton Océanique, CNRS, UMR 7144Roscoff, France
| | - Christian Kolowrat
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- Groupe Plancton Océanique, CNRS, UMR 7144Roscoff, France
- Center for Doctoral Studies, University of ViennaVienna, Austria
| | - Laurence Garczarek
- Station Biologique, UPMC-Université Paris VIRoscoff, France
- Groupe Plancton Océanique, CNRS, UMR 7144Roscoff, France
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