1
|
The influence of bio-optical properties of Emiliania huxleyi and Tetraselmis sp. on biomass and lipid production when exposed to different light spectra and intensities of an adjustable LED array and standard light sources. SN APPLIED SCIENCES 2019. [DOI: 10.1007/s42452-019-0529-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
|
2
|
Wei Y, Zhao X, Sun J, Liu H. Fast Repetition Rate Fluorometry (FRRF) Derived Phytoplankton Primary Productivity in the Bay of Bengal. Front Microbiol 2019; 10:1164. [PMID: 31244786 PMCID: PMC6544007 DOI: 10.3389/fmicb.2019.01164] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 05/07/2019] [Indexed: 11/13/2022] Open
Abstract
The approach of fast repetition rate fluorometry (FRRF) requires a conversion factor (Φe : C/n PSII) to derive ecologically-relevant carbon uptake rates (PP z,t). However, the required Φe : C/n PSII is commonly measured by 14C assimilation and varies greatly across phytoplankton taxonomy and environmental conditions. Consequently, the use of FRRF to estimate gross primary productivity (GP z,t), alone or in combination with other approaches, has been restricted by both inherent conversion and procedural inconsistencies. Within this study, based on a hypothesis that the non-photochemical quenching (NPQNSV) can be used as a proxy for the variability and magnitude of Φe : C/n PSII, we thus proposed an independent field model coupling with the NPQNSV-based Φe : C/n PSII for FRRF-derived carbon, without the need for additional Φe : C/n PSII in the Bay of Bengal (BOB). Therewith, this robust algorithm was verified by the parallel measures of electron transport rates and 14C-uptake PP z,t. NPQNSV is theoretically caused by the effects of excess irradiance pressure, however, it showed a light and depth-independent response on large spatial scales of the BOB. Trends observed for the maximum quantum efficiency (Fv/Fm), the quantum efficiency of energy conversion ( F q ' / F m ' ) and the efficiency of charge separation ( F q ' / F v ' ) were similar and representative, which displayed a relative maximum at the subsurface and were collectively limited by excess irradiance. In particular, most observed values of Fv/Fm in the BOB were only about half of the values expected for nutrient replete phytoplankton. FRRF-based estimates of electron transport at PSII (ETRRCII) varied significantly, from 0.01 to 8.01 mol e- mol RCII-1 s-1, and showed profound responses to depth and irradiance across the BOB, but fitting with the logistic model. N, P, and irradiance are key environmental drivers in explaining the broad-scale variability of photosynthetic parameters. Furthermore, taxonomic shifts and physiological changes may be better predictors of photosynthetic parameters, and facilitate the selection of better adapted species to optimize photosynthetic efficiency under any particular set of ambient light condition.
Collapse
Affiliation(s)
- Yuqiu Wei
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Xiangwei Zhao
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| | - Jun Sun
- Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, China.,Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin University of Science and Technology, Tianjin, China
| | - Haijiao Liu
- Institute of Marine Science and Technology, Shandong University, Qingdao, China
| |
Collapse
|
3
|
Yuan W, Gao G, Shi Q, Xu Z, Wu H. Combined effects of ocean acidification and warming on physiological response of the diatom Thalassiosira pseudonana to light challenges. MARINE ENVIRONMENTAL RESEARCH 2018; 135:63-69. [PMID: 29397992 DOI: 10.1016/j.marenvres.2018.01.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/15/2018] [Accepted: 01/22/2018] [Indexed: 06/07/2023]
Abstract
Diatoms are one of the most important groups of phytoplankton in terms of abundance and ecological functionality in the ocean. They usually dominate the phytoplankton communities in coastal waters and experience frequent and large fluctuations in light. In order to evaluate the combined effects of ocean warming and acidification on the diatom's exploitation of variable light environments, we grew a globally abundant diatom Thalassiosira pseudonana under two levels of temperature (18, 24 °C) and pCO2 (400, 1000 μatm) to examine its physiological performance after light challenge. It showed that the higher temperature increased the photoinactivation rate in T. pseudonana at 400 μatm pCO2, while the higher pCO2 alleviated the negative effect of the higher temperature on PSII photoinactivation. Higher pCO2 stimulated much faster PsbA removal, but it still lagged behind the photoinactivation of PSII under high light. Although the sustained phase of nonphotochemical quenching (NPQs) and activity of superoxide dismutase (SOD) were provoked during the high light exposure in T. pseudonana under the combined pCO2 and temperature conditions, it could not offset the damage caused by these multiple environmental changes, leading to decreased maximum photochemical yield.
Collapse
Affiliation(s)
- Wubiao Yuan
- Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology, Wuhan 430068, China
| | - Guang Gao
- Marine Resources Development Institute of Jiangsu, Huaihai Institute of Technology, Lianyungang 222005, China
| | - Qi Shi
- Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology, Wuhan 430068, China
| | - Zhiguang Xu
- College of Life Science, Ludong University, Yantai 264025, China
| | - Hongyan Wu
- Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology, Wuhan 430068, China; College of Life Science, Ludong University, Yantai 264025, China.
| |
Collapse
|
4
|
Jin P, Gao G, Liu X, Li F, Tong S, Ding J, Zhong Z, Liu N, Gao K. Contrasting Photophysiological Characteristics of Phytoplankton Assemblages in the Northern South China Sea. PLoS One 2016; 11:e0153555. [PMID: 27195824 PMCID: PMC4873168 DOI: 10.1371/journal.pone.0153555] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 03/31/2016] [Indexed: 12/11/2022] Open
Abstract
The growth of phytoplankton and thus marine primary productivity depend on photophysiological performance of phytoplankton cells that respond to changing environmental conditions. The South China Sea (SCS) is the largest marginal sea of the western Pacific and plays important roles in modulating regional climate and carbon budget. However, little has been documented on photophysiological characteristics of phytoplankton in the SCS. For the first time, we investigated photophysiological characteristics of phytoplankton assemblages in the northern South China Sea (NSCS) using a real-time in-situ active chlorophyll a fluorometry, covering 4.0 × 105 km2. The functional absorption cross section of photosystem II (PSII) in darkness (σPSII) or under ambient light (σPSII’) (A2 quanta-1) increased from the surface to deeper waters at all the stations during the survey period (29 July to 23 August 2012). While the maximum (Fv/Fm, measured in darkness) or effective (Fq’/Fm’, measured under ambient light) photochemical efficiency of PSII appeared to increase with increasing depth at most stations, it showed inverse relationship with depth in river plume areas. The functional absorption cross section of PSII changes could be attributed to light-adapted genotypic feature due to niche-partition and the alteration of photochemical efficiency of PSII could be attributed to photo-acclimation. The chlorophyll a fluorometry can be taken as an analog to estimate primary productivity, since areas of higher photochemical efficiency of PSII coincided with those of higher primary productivity reported previously in the NSCS.
Collapse
Affiliation(s)
- Peng Jin
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
| | - Guang Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
| | - Xin Liu
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
| | - Futian Li
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
| | - Shanying Tong
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
| | - Jiancheng Ding
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
| | - Zhihai Zhong
- Marine Biology Institute, Shantou University, Shantou, Guangdong 515063, China
| | - Nana Liu
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
- * E-mail:
| |
Collapse
|
5
|
Carrillo P, Medina-Sánchez JM, Herrera G, Durán C, Segovia M, Cortés D, Salles S, Korbee N, L. Figueroa F, Mercado JM. Interactive Effect of UVR and Phosphorus on the Coastal Phytoplankton Community of the Western Mediterranean Sea: Unravelling Eco-Physiological Mechanisms. PLoS One 2015; 10:e0142987. [PMID: 26599583 PMCID: PMC4658109 DOI: 10.1371/journal.pone.0142987] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/29/2015] [Indexed: 12/17/2022] Open
Abstract
Some of the most important effects of global change on coastal marine systems include increasing nutrient inputs and higher levels of ultraviolet radiation (UVR, 280-400 nm), which could affect primary producers, a key trophic link to the functioning of marine food webs. However, interactive effects of both factors on the phytoplankton community have not been assessed for the Mediterranean Sea. An in situ factorial experiment, with two levels of ultraviolet solar radiation (UVR+PAR vs. PAR) and nutrients (control vs. P-enriched), was performed to evaluate single and UVR×P effects on metabolic, enzymatic, stoichiometric and structural phytoplanktonic variables. While most phytoplankton variables were not affected by UVR, dissolved phosphatase (APAEX) and algal P content increased in the presence of UVR, which was interpreted as an acclimation mechanism of algae to oligotrophic marine waters. Synergistic UVR×P interactive effects were positive on photosynthetic variables (i.e., maximal electron transport rate, ETRmax), but negative on primary production and phytoplankton biomass because the pulse of P unmasked the inhibitory effect of UVR. This unmasking effect might be related to greater photodamage caused by an excess of electron flux after a P pulse (higher ETRmax) without an efficient release of carbon as the mechanism to dissipate the reducing power of photosynthetic electron transport.
Collapse
Affiliation(s)
- Presentación Carrillo
- Instituto del Agua, Universidad de Granada, Granada, Spain
- Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - Juan M. Medina-Sánchez
- Instituto del Agua, Universidad de Granada, Granada, Spain
- Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | | | - Cristina Durán
- Instituto del Agua, Universidad de Granada, Granada, Spain
| | - María Segovia
- Departamento de Ecología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Dolores Cortés
- Centro Oceanográfico de Málaga, Instituto Español de Oceanografía Fuengirola, Málaga, Spain
| | - Soluna Salles
- Centro Oceanográfico de Málaga, Instituto Español de Oceanografía Fuengirola, Málaga, Spain
| | - Nathalie Korbee
- Departamento de Ecología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Félix L. Figueroa
- Departamento de Ecología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Jesús M. Mercado
- Centro Oceanográfico de Málaga, Instituto Español de Oceanografía Fuengirola, Málaga, Spain
| |
Collapse
|
6
|
Segovia M, Mata T, Palma A, García-Gómez C, Lorenzo R, Rivera A, Figueroa FL. Dunaliella tertiolecta(Chlorophyta) Avoids Cell Death Under Ultraviolet Radiation By Triggering Alternative Photoprotective Mechanisms. Photochem Photobiol 2015. [DOI: 10.1111/php.12502] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- María Segovia
- Department of Ecology; Faculty of Sciences; University of Málaga; Málaga Spain
| | - Teresa Mata
- Department of Ecology; Faculty of Sciences; University of Málaga; Málaga Spain
| | - Armando Palma
- Department of Ecology; Faculty of Sciences; University of Málaga; Málaga Spain
| | | | - Rosario Lorenzo
- Department of Ecology; Faculty of Sciences; University of Málaga; Málaga Spain
| | - Alicia Rivera
- Department of Cell Biology; Faculty of Sciences; University of Málaga; Málaga Spain
| | - Félix L. Figueroa
- Department of Ecology; Faculty of Sciences; University of Málaga; Málaga Spain
| |
Collapse
|
7
|
Häder DP, Richter PR, Villafañe VE, Helbling EW. Influence of light history on the photosynthetic and motility responses of Gymnodinium chlorophorum exposed to UVR and different temperatures. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 138:273-81. [PMID: 24998868 DOI: 10.1016/j.jphotobiol.2014.05.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/20/2014] [Accepted: 05/26/2014] [Indexed: 12/01/2022]
Abstract
In the wake of global climate change, phytoplankton productivity and species composition is expected to change due to altered external conditions such as temperature, nutrient accessibility, pH and exposure to solar visible (PAR) and ultraviolet radiation (UVR). The previous light history is also of importance for the performance of phytoplankton cells. In order to assess the combined impacts of UVR and temperature on the dinoflagellate Gymnodinium chlorophorum we analyzed the effective photochemical quantum yield (Y), relative electron transport rate vs. irradiance curves (rETR vs. I), percentage of motile cells and swimming velocity. Cells were grown at three different temperatures (15, 20 and 25 °C) and two PAR intensities: low light (LL, 100 μmol photons m(-2) s(-1)) and high light (HL, 250 μmol photons m(-2) s(-1)). Pre-acclimated cells were then exposed to either PAR only (P), PAR+UV-A (PA) or PAR+UV-A+UV-B (PAB) radiation at two different irradiances, followed by a recovery period in darkness. The Y decreased during exposure, being least inhibited in P and most in PAB treatments. Inhibition was higher and recovery slower in LL-grown cells than in HL-grown cells at 15° and 20 °C, but the opposite occurred at 25 °C, when exposed to high irradiances. Maximal values of rETR were determined at t0 as compared to the different (before and after exposure) radiation treatments. The effects of temperature and UVR on rETR were antagonistic in LL-grown cells (i.e., less UVR inhibition at higher temperature), while it was synergistic in HL cells. Swimming velocity and percentage of motile cells were not affected at all tested temperatures and exposure regimes, independent of the light history. Our results indicate that, depending on the previous light history, increased temperature and UVR as predicted under climate change conditions, can have different interactions thus conditioning the photosynthetic response of G. chlorophorum.
Collapse
Affiliation(s)
| | - Peter R Richter
- Friedrich-Alexander Universität, Department Biologie, Lehrstuhl für Zellbiologie, AG für Gravitationsbiologie, Staudtstr. 5, 90158 Erlangen, Germany.
| | - Virginia E Villafañe
- ESTACIÓN de Fotobiología Playa Unión, Casilla de Correo 15, U9103ZAA Rawson, Chubut, Argentina.
| | - E Walter Helbling
- ESTACIÓN de Fotobiología Playa Unión, Casilla de Correo 15, U9103ZAA Rawson, Chubut, Argentina.
| |
Collapse
|
8
|
Response of phytoplankton photophysiology to varying environmental conditions in the Sub-Antarctic and Polar Frontal Zone. PLoS One 2013; 8:e72165. [PMID: 23977242 PMCID: PMC3747055 DOI: 10.1371/journal.pone.0072165] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 07/12/2013] [Indexed: 11/19/2022] Open
Abstract
Climate-driven changes are expected to alter the hydrography of the Sub-Antarctic Zone (SAZ) and Polar Frontal Zone (PFZ) south of Australia, in which distinct regional environments are believed to be responsible for the differences in phytoplankton biomass in these regions. Here, we report how the dynamic influences of light, iron and temperature, which are responsible for the photophysiological differences between phytoplankton in the SAZ and PFZ, contribute to the biomass differences in these regions. High effective photochemical efficiency of photosystem II (F'(q)/F'(m)0.4), maximum photosynthesis rate (P(B)(max)), light-saturation intensity (E(k)), maximum rate of photosynthetic electron transport (1/[Symbol: see text]PSII), and low photoprotective pigment concentrations observed in the SAZ correspond to high chlorophyll a and iron concentrations. In contrast, phytoplankton in the PFZ exhibits low F'(q)/F'(M) (~ 0.2) and high concentrations of photoprotective pigments under low light environment. Strong negative relationships between iron, temperature, and photoprotective pigments demonstrate that cells were producing more photoprotective pigments under low temperature and iron conditions, and are responsible for the low biomass and low productivity measured in the PFZ. As warming and enhanced iron input is expected in this region, this could probably increase phytoplankton photosynthesis in this region. However, complex interactions between the biogeochemical processes (e.g. stratification caused by warming could prevent mixing of nutrients), which control phytoplankton biomass and productivity, remain uncertain.
Collapse
|
9
|
Alderkamp AC, Kulk G, Buma AGJ, Visser RJW, Van Dijken GL, Mills MM, Arrigo KR. THE EFFECT OF IRON LIMITATION ON THE PHOTOPHYSIOLOGY OF PHAEOCYSTIS ANTARCTICA (PRYMNESIOPHYCEAE) AND FRAGILARIOPSIS CYLINDRUS (BACILLARIOPHYCEAE) UNDER DYNAMIC IRRADIANCE(1). JOURNAL OF PHYCOLOGY 2012; 48:45-59. [PMID: 27009649 DOI: 10.1111/j.1529-8817.2011.01098.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The effects of iron limitation on photoacclimation to dynamic irradiance were studied in Phaeocystis antarctica G. Karst. and Fragilariopsis cylindrus (Grunow) W. Krieg. in terms of growth rate, photosynthetic parameters, pigment composition, and fluorescence characteristics. Under dynamic light conditions mimicking vertical mixing below the euphotic zone, P. antarctica displayed higher growth rates than F. cylindrus both under iron (Fe)-replete and Fe-limiting conditions. Both species showed xanthophyll de-epoxidation that was accompanied by low levels of nonphotochemical quenching (NPQ) during the irradiance maximum of the light cycle. The potential for NPQ at light levels corresponding to full sunlight was substantial in both species and increased under Fe limitation in F. cylindrus. Although the decline in Fv /Fm under Fe limitation was similar in both species, the accompanying decrease in the maximum rate of photosynthesis and growth rate was much stronger in F. cylindrus. Analysis of the electron transport rates through PSII and on to carbon (C) fixation revealed a large potential for photoprotective cyclic electron transport (CET) in F. cylindrus, particularly under Fe limitation. Probably, CET aided the photoprotection in F. cylindrus, but it also reduced photosynthetic efficiency at higher light intensities. P. antarctica, on the other hand, was able to efficiently use electrons flowing through PSII for C fixation at all light levels, particularly under Fe limitation. Thus, Fe limitation enhanced the photophysiological differences between P. antarctica and diatoms, supporting field observations where P. antarctica is found to dominate deeply mixed water columns, whereas diatoms dominate shallower mixed layers.
Collapse
Affiliation(s)
- Anne-Carlijn Alderkamp
- Department of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands Department of Environmental Earth System Science, Stanford University, Stanford, California 94305, USADepartment of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The NetherlandsDepartment of Environmental Earth System Science, Stanford University, Stanford, California 94305, USA
| | - Gemma Kulk
- Department of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands Department of Environmental Earth System Science, Stanford University, Stanford, California 94305, USADepartment of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The NetherlandsDepartment of Environmental Earth System Science, Stanford University, Stanford, California 94305, USA
| | - Anita G J Buma
- Department of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands Department of Environmental Earth System Science, Stanford University, Stanford, California 94305, USADepartment of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The NetherlandsDepartment of Environmental Earth System Science, Stanford University, Stanford, California 94305, USA
| | - Ronald J W Visser
- Department of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands Department of Environmental Earth System Science, Stanford University, Stanford, California 94305, USADepartment of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The NetherlandsDepartment of Environmental Earth System Science, Stanford University, Stanford, California 94305, USA
| | - Gert L Van Dijken
- Department of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands Department of Environmental Earth System Science, Stanford University, Stanford, California 94305, USADepartment of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The NetherlandsDepartment of Environmental Earth System Science, Stanford University, Stanford, California 94305, USA
| | - Matthew M Mills
- Department of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands Department of Environmental Earth System Science, Stanford University, Stanford, California 94305, USADepartment of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The NetherlandsDepartment of Environmental Earth System Science, Stanford University, Stanford, California 94305, USA
| | - Kevin R Arrigo
- Department of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands Department of Environmental Earth System Science, Stanford University, Stanford, California 94305, USADepartment of Ocean Ecosystems, Energy and Sustainability Research Institute, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The NetherlandsDepartment of Environmental Earth System Science, Stanford University, Stanford, California 94305, USA
| |
Collapse
|
10
|
Abstract
Coral reefs are one of the most important marine ecosystems, providing habitat for approximately a quarter of all marine organisms. Within the foundation of this ecosystem, reef-building corals form mutualistic symbioses with unicellular photosynthetic dinoflagellates of the genus Symbiodinium. Exposure to UV radiation (UVR) (280 to 400 nm) especially when combined with thermal stress has been recognized as an important abiotic factor leading to the loss of algal symbionts from coral tissue and/or a reduction in their pigment concentration and coral bleaching. UVR may damage biological macromolecules, increase the level of mutagenesis in cells, and destabilize the symbiosis between the coral host and their dinoflagellate symbionts. In nature, corals and other marine organisms are protected from harmful UVR through several important photoprotective mechanisms that include the synthesis of UV-absorbing compounds such as mycosporine-like amino acids (MAAs). MAAs are small (<400-Da), colorless, water-soluble compounds made of a cyclohexenone or cyclohexenimine chromophore that is bound to an amino acid residue or its imino alcohol. These secondary metabolites are natural biological sunscreens characterized by a maximum absorbance in the UVA and UVB ranges of 310 to 362 nm. In addition to their photoprotective role, MAAs act as antioxidants scavenging reactive oxygen species (ROS) and suppressing singlet oxygen-induced damage. It has been proposed that MAAs are synthesized during the first part of the shikimate pathway, and recently, it has been suggested that they are synthesized in the pentose phosphate pathway. The shikimate pathway is not found in animals, but in plants and microbes, it connects the metabolism of carbohydrates to the biosynthesis of aromatic compounds. However, both the complete enzymatic pathway of MAA synthesis and the extent of their regulation by environmental conditions are not known. This minireview discusses the current knowledge of MAA synthesis, illustrates the diversity of MAA functions, and opens new perspectives for future applications of MAAs in biotechnology.
Collapse
|
11
|
Häder DP, Helbling EW, Williamson CE, Worrest RC. Effects of UV radiation on aquatic ecosystems and interactions with climate change. Photochem Photobiol Sci 2011; 10:242-60. [PMID: 21253662 DOI: 10.1039/c0pp90036b] [Citation(s) in RCA: 266] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The health of freshwater and marine ecosystems is critical to life on Earth. The impact of solar UV-B radiation is one potential stress factor that can have a negative impact on the health of certain species within these ecosystems. Although there is a paucity of data and information regarding the effect of UV-B radiation on total ecosystem structure and function, several recent studies have addressed the effects on various species within each trophic level. Climate change, acid deposition, and changes in other anthropogenic stressors such as pollutants alter UV exposure levels in inland and coastal marine waters. These factors potentially have important consequences for a variety of aquatic organisms including waterborne human pathogens. Recent results have demonstrated the negative impacts of exposure to UV-B radiation on primary producers, including effects on cyanobacteria, phytoplankton, macroalgae and aquatic plants. UV-B radiation is an environmental stressor for many aquatic consumers, including zooplankton, crustaceans, amphibians, fish, and corals. Many aquatic producers and consumers rely on avoidance strategies, repair mechanisms and the synthesis of UV-absorbing substances for protection. However, there has been relatively little information generated regarding the impact of solar UV-B radiation on species composition within natural ecosystems or on the interaction of organisms between trophic levels within those ecosystems. There remains the question as to whether a decrease in population size of the more sensitive primary producers would be compensated for by an increase in the population size of more tolerant species, and therefore whether there would be a net negative impact on the absorption of atmospheric carbon dioxide by these ecosystems. Another question is whether there would be a significant impact on the quantity and quality of nutrients cycling through the food web, including the generation of food proteins for humans. Interactive effects of UV radiation with changes in other stressors, including climate change and pollutants, are likely to be particularly important.
Collapse
|
12
|
Brunet C, Lavaud J. Can the xanthophyll cycle help extract the essence of the microalgal functional response to a variable light environment? JOURNAL OF PLANKTON RESEARCH 2010; 32:1609-1617. [PMID: 0 DOI: 10.1093/plankt/fbq104] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
|