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  • 1
    Electronic Resource
    Electronic Resource
    The marine ecosystem of Kongsfjorden, Svalbard (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Polar research 21 (2002), S. 0 
    Details
    ISSN: 1751-8369
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography , Geosciences
    Notes: Kongsfjorden is a glacial fjord in the Arctic (Svalbard) that is influenced by both Atlantic and Arctic water masses and harbours a mixture of boreal and Arctic flora and fauna. Inputs from large tidal glaciers create steep environmental gradients in sedimentation and salinity along the length of this fjord. The glacial inputs cause reduced biomass and diversity in the benthic community in the inner fjord. Zooplankton suffers direct mortality from the glacial outflow and primary production is reduced because of limited light levels in the turbid, mixed inner waters. The magnitude of the glacial effects diminishes towards the outer fjord. Kongsfjorden is an important feeding ground for marine mammals and seabirds. Even though the fjord contains some boreal fauna, the prey consumed by upper trophic levels is mainly Arctic organisms. Marine mammals constitute the largest top-predator biomass, but seabirds have the largest energy intake and also export nutrients and energy out of the marine environment. Kongsfjorden has received a lot of research attention in the recent past. The current interest in the fjord is primarily based on the fact that Kongsfjorden is particularly suitable as a site for exploring the impacts of possible climate changes, with Atlantic water influx and melting of tidal glaciers both being linked to climate variability. The pelagic ecosystem is likely to be most sensitive to the Atlantic versus Arctic influence, whereas the benthic ecosystem is more affected by long-term changes in hydrography as well as changes in glacial runoff and sedimentation. Kongsfjorden will be an important Arctic monitoring site over the coming decades and a review of the current knowledge, and a gap analysis, are therefore warranted. Important knowledge gaps include a lack of quantitative data on production, abundance of key prey species, and the role of advection on the biological communities in the fjord.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1751-8369.2002.tb00073.x
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  • 2
    Electronic Resource
    Electronic Resource
    The physical environment of Kongsfjorden–Krossfjorden, an Arctic fjord system in Svalbard (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Polar research 21 (2002), S. 0 
    Details
    ISSN: 1751-8369
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography , Geosciences
    Notes: Kongsfjorden-Krossfjorden and the adjacent West Spitsbergen Shelf meet at the common mouth of the two fjord arms. This paper presents our most up-to-date information about the physical environment of this fjord system and identifies important gaps in knowledge. Particular attention is given to the steep physical gradients along the main fjord axis, as well as to seasonal environmental changes. Physical processes on different scales control the large-scale circulation and small-scale (irreversible) mixing of water and its constituents. It is shown that, in addition to the tide, run-off (glacier ablation, snowmelt, summer rainfall and ice calving) and local winds are the main driving forces acting on the upper water masses in the fjord system. The tide is dominated by the semi-diurnal component and the freshwater supply shows a marked seasonal variation pattern and also varies interannually. The wind conditions are characterized by prevailing katabatic winds, which at times are strengthened by the geostrophic wind field over Svalbard. Rotational dynamics have a considerable influence on the circulation patterns within the fjord system and give rise to a strong interaction between the fjord arms. Such dynamics are also the main reason why variations in the shelf water density field, caused by remote forces (tide and coastal winds), propagate as a Kelvin wave into the fjord system. This exchange affects mainly the intermediate and deep water, which is also affected by vertical convection processes driven by cooling of the surface and brine release during ice formation in the inner reaches of the fjord arms. Further aspects covered by this paper include the geological and geomorphological characteristics of the Kongsfjorden area, climate and meteorology, the influence of glaciers, freshwater supply, sea ice conditions, sedimentation processes as well as underwater radiation conditions. The fjord system is assumed to be vulnerable to possible climate changes, and thus is very suitable as a site for the demonstration and investigation of phenomena related to climate change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1751-8369.2002.tb00072.x
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  • 3
    Electronic Resource
    Electronic Resource
    Habitat related variation in UV tolerance of tropical marine red macrophytes is not temperature dependent (2003)
    Oxford, UK : Blackwell Science Ltd
    Physiologia plantarum 118 (2003), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Because tropical marine macrophytes experience high ultraviolet-B radiation (UVBR: 280–320 nm) it is assumed that they have high UV tolerance. This was investigated by examining the relative UV sensitivity of five Caribbean red macrophytes. Furthermore, the possibility of temperature dependence of UV effects was examined over a tropical temperature range. Algal fragments of intertidally occurring Gelidiopsis planicaulis (Taylor) Taylor, Wurdemannia miniata (Duby) Feldman and Hamel, and Hypnea spinella (Agardh) Kützing, and the subtidal species Bryothamnion triquetrum (Gmelin) Howe and Heterosiphonia gibbesii (Harvey) Falkenberg were repeatedly subjected to artificial UVBR and ultraviolet-A radiation (UVAR: 320–400 nm) at 22, 26 and 30°C, whereas exposure to photosynthetically active radiation (PAR) served as control. Growth rates, optimal quantum yield of PSII and accumulation of DNA damage were monitored for 10 days, whereas the relative abundance of the D1 reaction centre binding protein and the presence of UV absorbing compounds were investigated in some samples. UVAR and UVBR significantly depressed growth rates of all species. UVBR exposure caused accumulation of DNA damage and resulted in stronger growth reduction than UVAR. UVBR and UVAR caused a depression of optimal quantum yield and a lower D1 abundance. However, the former recovered fast and acclimated to the UV treatments. Some species produced UV absorbing compounds in response to UVAR. UV exposure caused less pronounced effects in intertidally occurring species than in subtidal species. UV effects on growth, the accumulation of DNA damage and UV induced depression of optimal quantum yield were independent of temperature in most species. We conclude that high UVBR in tropical regions may depress in situ growth rates of these intertidal and subtidal red macrophytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2003.00090.x
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  • 4
    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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  • 5
    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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  • 6
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    Photosynthetic characteristics and mycosporine-like amino acids under UV-radiation: a competitive advantage of Mastocarpus stellatus over Chondrus crispus at the Helgoland shoreline? (2000)
    In:  EPIC3Helgoland Marine Research 54, pp. 47-52
    Details
    Publication Date: 2019-07-17
    Description: Abstract Chondrus crispus and Mastocarpus stellatus both inhabit the intertidal and upper sublittoral zone of Helgoland, but with C.crispus generally taking a lower position. Measurements of chlorophyll fluorescence, activity of ribulose-1,5-bisphosphatecarboxylase/oxygenase (RubisCO), and content and composition of UV absorbing mycosporine-like amino acids (MAAs) were conducted inthe laboratory, to test whether susceptibility to UV radiation may play a role in the vertical distribution of these two species. Effective andmaximal quantum yield of photochemistry as well as maximal electron transport rate (ETRmax) in C. crispus were more strongly affected byUV-B radiation than in M. stellatus. In both species, no negative effects of the respective radiation conditions were found on total activity ofRubisCO. Total MAA content in M. stellatus was up to 6-fold higher than in C. crispus and the composition of MAAs in the two specieswas different. The results indicate that, among others, UV-B sensitivity may be a factor restricting C. crispus to the lower intertidal andupper sublittoral zone, whereas M. stellatus is better adapted to UV radiation and is therefore more competitive in the upper intertidal zone.Key words Chondrus crispus · Chlorophyll fluorescence · Mastocarpus stellatus · Mycosporine-like amino acids · UV radiation
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 7
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    Wavelength-dependent induction of UV-absorbing mycosporine-like amino acids in the red alga Chondrus crispus under natural solar radiation (2002)
    In:  EPIC3Journal of Experimental Marine Biology and Ecology, 268, pp. 69-82, ISSN: 0022-0981
    Details
    Publication Date: 2019-07-17
    Description: Polychromatic response spectra for the induction of UV absorbing mycosporine-like amino acids (MAAs) were calculated after exposing small thalli of the red alga Chondrus crispus under various cut-off-filters to natural solar radiation on the North Sea island Helgoland, Germany. The laboratory grown specimens, typically contain only traces of palythine and synthesise five different MAAs rapidly and in high concentrations after being transplanted into shallow water. The resulting qualitative and quantitative patterns of MAA induction differed markedly with respect to spectral distribution. Furthermore, the wavebands effective for MAA induction vary within the MAA. UV-B radiation had a negative effect on the accumulation of the major MAAs shinorine (lmax = 334 nm) and palythine (lmax = 320 nm), while short wavelength UV-A exhibits the highest quantum efficiency on their synthesis. In contrast, the synthesis of asterina-330 (lmax = 330 nm), palythinol (lmax = 332 nm) and palythene (lmax = 360 nm) was mainly induced by UV-B radiation. Whether the synthesis of shinorine and palythine is induced by a photoreceptor with an absorption maximum in the short wavelength UV-A and whether a second photoreceptor absorbing UV-B radiation is responsible for the induction of asterina-330, palythinol and palythene remains to be studied.Our results show that C. crispus has a high capacity to adapt flexibly the qualitative and quantitative MAA concentration to the prevailing spectral distribution of irradiance. On the one hand, this is regarded as an important aspect with respect to the acclimation of algae to increasing UV-B irradiance in the context of ongoing depletion of stratospheric ozone. On the other hand the experiment demonstrates that UV-A irradiance is more important for the induction of the major MAAs shinorine and palythine than UV-B.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 8
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    The ecosystem of Kongsfjorden, Svalbard (2002)
    In:  EPIC3Polar research, 21, pp. 167-208
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    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 9
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    Seasonal variation in ecophysiological patterns in macroalgae from an Arctic fjord: II. Pigment accumulation and biochemical defence systems (2002)
    In:  EPIC3Marine Biology 140, pp. 1087-1095
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    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 10
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    Seasonal variation in ecophysiological patterns in macroalgae from an Arctic fjord: I. Sensitivity of photosynthesis to ultraviolet radiation (2002)
    In:  EPIC3Marine Biology:, 140, pp. 1097-1106
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    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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