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  • 1
    Electronic Resource
    Electronic Resource
    Acclimation of brown algal photosynthesis to ultraviolet radiation in Arctic coastal waters (Spitsbergen, Norway) (1998)
    Springer
    Polar biology 20 (1998), S. 388-395 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In field studies conducted at the Kongsfjord (Spitsbergen) changes of the irradiance in the atmosphere and the sublittoral zone were monitored from the beginning of June until the end of August 1997, to register the minimum and maximum fluxes of ultraviolet and photosynthetically active radiation and to characterise the underwater light climate. Measurements of photosynthesis in three abundant brown algal species (Alaria esculenta, Laminaria saccharina, Saccorhiza dermatodea) were conducted to test whether their photosynthetic performance reflects changing light climate in accordance with depth. Plants sampled at various depths were exposed to controlled fluence rates of photosynthetically active radiation (400–700 nm), UV-A (320–400 nm) and UV-B (280–320 nm). Changes in photosynthetic performance during the treatments were monitored by measuring variable chlorophyll fluorescence of photosystem II. In each species, the degree of inhibition of photosynthesis was related to the original collection depth, i.e. shallow-water isolates were more resistant than plants from deeper waters. The results show that macroalgae acclimate effectively to increasing irradiance levels for both photosynthetically active and ultraviolet radiation. However, the kinetics of acclimation are different within the different species. It is shown that one important strategy to cope with higher irradiance levels in shallow waters is the capability for a faster recovery from high light stress compared to isolates from deeper waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050319
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Photosynthesis of two Arctic macroalgae under different ambient radiation levels and their sensitivity to enhanced UV radiation (2000)
    Springer
    Polar biology 23 (2000), S. 257-264 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The change in optimal quantum efficiency (F v/F m) of the Arctic species Laminaria saccharina and Palmaria palmata was investigated in a long-term experiment in situ under different radiation levels during the summer of 1997 in the Kongsfjord (Ny-Ålesund, Spitsbergen, Norway, 78°55.5′N, 11°56.0′E). Whole plants were incubated in an open box system made of UV-transparent Perspex and exposed to solar radiation (λ〉295 nm), solar radiation excluding UVB (λ 〉 320 nm) and solar radiation excluding UVA + UVB (λ 〉 400 nm). Increasing radiation levels were simulated by transplantation of the pre-adapted algae from their growth depth at 2 m to a water depth of 1 m. Sensitivity to artificially increased UV radiation was determined by exposure of algae from the three treatments to 6 h of strong UV radiation. P. palmata was relatively insensitive to increasing UV radiation and recovered very fast and almost completely in 2 h. Even plants pre-cultured in ambient radiation levels excluding UVA + UVB or UVB only showed no photoinhibition after exposure to extra UV radiation in the laboratory. L. saccharina was, in comparison to P. palmata, more sensitive and showed photoinhibition under solar radiation and solar minus UVB radiation after transplantation from 2 to 1 m water depth. However, after 3 weeks at 1 m depth, F v/F m of L. saccharina was equal in all treatments and restored to the original values at the start of the experiment. Sensitivity to extra UV radiation in the laboratory increased in time, although recovery was also fast and occurred within 20 h.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050442
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of ultraviolet radiation on photosynthesis and related enzyme reactions of marine macroalgae (2000)
    Springer
    Planta 211 (2000), S. 555-562 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Macroalgae – Photosynthesis – Ribulose-1, 5-bisphosphate carboxylase/oxygenase – UV radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract.  Changes in physiological parameters related to photosynthesis were studied in five macroalgal species from Spitsbergen (Monostroma arcticum, Laminaria solidungula, Alaria esculenta, Palmaria palmata, Phycodrys rubens) during a 72-h exposure to UV radiation. Maximal quantum yield of photochemistry (Fv/Fm) and maximal electron transport rate (ETRmax) were measured with a pulse-amplitude-modulated fluorometer; the activity of the Calvin cycle enzymes ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and glyceraldehyde-3-phosphate dehydrogenase (G3PDH) were estimated using a photometric test. Proteins of crude extracts were separated by SDS gel electrophoresis and changes in cellular concentrations of Rubisco were determined. Moreover, the concentration of chlorophyll a (Chl a), and protein content, were measured photometrically. In all species, Chl a content, maximal quantum yield as well as ETRmax decreased during the UV treatment. Changes in ETRmax were related to the changes in the overall activity of Rubisco. Analysis of SDS gels showed that in P. rubens, L. solidungula, M. arcticum and A. esculenta decreasing Rubisco activity partly resulted from a degradation of the enzyme. However, in A. esculenta, the formation of a high-molecular-weight polypeptide was observed. In all species, the activity of Rubisco was more strongly impaired than that of G3PDH. Exposure to UV resulted in loss of total protein only in the deepwater species L. solidungula and P. rubens. The different sensitivities to UV exposure of the species tested reflect their zonation pattern in the field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250000313
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    Paper (German National Licenses)
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  • 4
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    Physiological responses of the calcifying rhodophyte, Corallina officinalis (L.), to future CO2 levels (2012)
    Springer
    In:  Marine Biology, 159 (4). pp. 783-792.
    Details
    Publication Date: 2020-07-14
    Description: Future atmospheric CO2 levels will most likely have complex consequences for marine organisms, particulary photosynthetic calcifying organisms. Corallina officinalis L. is an erect calcifying macroalga found in the inter- and subtidal regions of temperate rocky coastlines and provides important substrate and refugia for marine meiofauna. The main goal of the current study was to determine the physiological responses of C. officinalis to increased CO2 concentrations expected to occur within the next century and beyond. Our results show that growth and production of inorganic material decreased under high CO2 levels, while carbonic anhydrase activity was stimulated and negatively correlated to algal inorganic content. Photosynthetic efficiency based on oxygen evolution was also negatively affected by increased CO2. The results of this study indicate that C. officinalis may become less competitive under future CO2 levels, which could result in structural changes in future temperate intertidal communities.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00227-011-1854-9
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Nutrient availability affects the response of the calcifying chlorophyte Halimeda opuntia (L.) J.V. Lamouroux to low pH (2014)
    Springer
    In:  Planta, 239 (1). pp. 231-242.
    Details
    Publication Date: 2014-08-29
    Description: Atmospheric carbon dioxide emissions cause a decrease in the pH and aragonite saturation state of surface ocean water. As a result, calcifying organisms are expected to suffer under future ocean conditions, but their physiological responses may depend on their nutrient status. Because many coral reefs experience high inorganic nutrient loads or seasonal changes in nutrient availability, reef organisms in localized areas will have to cope with elevated carbon dioxide and changes in inorganic nutrients. Halimeda opuntia is a dominant calcifying primary producer on coral reefs that contributes to coral reef accretion. Therefore, we investigated the carbon and nutrient balance of H. opuntia exposed to elevated carbon dioxide and inorganic nutrients. We measured tissue nitrogen, phosphorus and carbon content as well as the activity of enzymes involved in inorganic carbon uptake and nitrogen assimilation (external carbonic anhydrase and nitrate reductase, respectively). Inorganic carbon content was lower in algae exposed to high CO2, but calcification rates were not significantly affected by CO2 or inorganic nutrients. Organic carbon was positively correlated to external carbonic anhydrase activity, while inorganic carbon showed the opposite correlation. Carbon dioxide had a significant effect on tissue nitrogen and organic carbon content, while inorganic nutrients affected tissue phosphorus and N:P ratios. Nitrate reductase activity was highest in algae grown under elevated CO2 and inorganic nutrient conditions and lowest when phosphate was limiting. In general, we found that enzymatic responses were strongly influenced by nutrient availability, indicating its important role in dictating the local responses of the calcifying primary producer H. opuntia to ocean acidification.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00425-013-1982-1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    CO2 and inorganic nutrient enrichment affect the performance of a calcifying green alga and its noncalcifying epiphyte (2015)
    Springer
    In:  Oecologia, 177 (4). pp. 1157-1169.
    Details
    Publication Date: 2015-06-30
    Description: Ocean acidification studies in the past decade have greatly improved our knowledge of how calcifying organisms respond to increased surface ocean CO2 levels. It has become evident that, for many organisms, nutrient availability is an important factor that influences their physiological responses and competitive interactions with other species. Therefore, we tested how simulated ocean acidification and eutrophication (nitrate and phosphate enrichment) interact to affect the physiology and ecology of a calcifying chlorophyte macroalga (Halimeda opuntia (L.) J.V. Lamouroux) and its common noncalcifying epiphyte (Dictyota sp.) in a 4-week fully crossed multifactorial experiment. Inorganic nutrient enrichment (+NP) had a strong influence on all responses measured with the exception of net calcification. Elevated CO2 alone significantly decreased electron transport rates of the photosynthetic apparatus and resulted in phosphorus limitation in both species, but had no effect on oxygen production or respiration. The combination of CO2 and +NP significantly increased electron transport rates in both species. While +NP alone stimulated H. opuntia growth rates, Dictyota growth was significantly stimulated by nutrient enrichment only at elevated CO2, which led to the highest biomass ratios of Dictyota to Halimeda. Our results suggest that inorganic nutrient enrichment alone stimulates several aspects of H. opuntia physiology, but nutrient enrichment at a CO2 concentration predicted for the end of the century benefits Dictyota sp. and hinders its calcifying basibiont H. opuntia.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1007/s00442-015-3242-5
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    Kongsfjorden as harbinger of the future Arctic: knowns, unknowns and research priorities (2019)
    Springer
    In:  EPIC3The Ecosystem of Kongsfjorden, Svalbard, The Ecosystem of Kongsfjorden, Svalbard, Cham, Springer, 566 p., pp. 537-562, ISBN: 978-3-319-46425-1
    Details
    Publication Date: 2020-07-08
    Description: Due to its year-round accessibility and excellent on-site infrastructure, Kongsfjorden and the Ny-Ålesund Research and Monitoring Facility have become established as a primary location to study the impact of environmental change on Arctic coastal ecosystems. Due to its location right at the interface of Arctic and Atlantic oceanic regimes, Kongsfjorden already experiences large amplitudes of variability in physico/chemical conditions and might, thus, be considered as an early warning indicator of future changes, which can then be extrapolated in a pan-Arctic perspective. Already now, Kongsfjorden represents one of the best-studied Arctic fjord systems. However, research conducted to date has concentrated largely on small disciplinary projects, prompting the need for a higher level of integration of future research activities. This contribution, thus, aims at identifying gaps in knowledge and research priorities with respect to ecological and adaptive responses to Arctic ecosystem changes. By doing so we aim to provide a stimulus for the initiation of new international and interdisciplinary research initiatives.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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    PAPER (OA)
  • 8
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    Acclimation to UV radiation and antioxidative defence in the endemic Antarctic brown macroalga Desmarestia anceps along a depth gradient (2013)
    Springer
    In:  EPIC3Polar Biology, Springer, 36(12), pp. 1779-1789, ISSN: 0722-4060
    Details
    Publication Date: 2017-06-05
    Description: The endemic Antarctic brown macroalga Desmarestia anceps colonizes the subtidal between 5 and 30 m in Potter Cove on King George Island (South Shetland Islands, Antarctica). Experiments were conducted to study photosynthetic activities, antioxidative enzymes and UV tolerance of field-grown individuals with respect to the light histories along different subtidal positions. Individuals collected from the upper (5.5 m) and mid-subtidal (9.0 m) are characterized by high maximum electron transport rates (ETRmax) measured by PAM-fluorometry and high activities of superoxide dismutase (SOD) supported by considerable activities of glutathione reductase. Individuals of this species from the upper subtidal are able to tolerate high irradiances of UV-B radiation because its photosynthetic apparatus is putatively well protected by phlorotannins. In contrast, individuals from lower subtidal positions (13.5 and 15.5 m) showed an opposite trend: lower ETRmax and SOD activities as well as a lower UV tolerance of photosynthesis. Moreover, a non-denaturing polyacrylamide gel electrophoresis (native PAGE) of a partially purified crude extract reveals that D. anceps has probably six isoforms of SOD. These intra-specific patterns imply a high phenotypical plasticity of D. anceps with respect to its photosynthesis and photoprotective mechanisms. Overall, photosynthesis, UV tolerance and antioxidative potential are highly regulated in D. anceps corresponding to the respective light regimes along its natural growth sites.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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