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  • 1
    Electronic Resource
    Electronic Resource
    Sensitivity of Laminariales zoospores from Helgoland (North Sea) to ultraviolet and photosynthetically active radiation: implications for depth distribution and seasonal reproduction (2005)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 28 (2005), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Depth distribution of kelp species in Helgoland (North Sea) is characterized by occurrence of Laminaria digitata in the upper sublittoral, whereas L. saccharina and L. hyperborea dominate the mid and lower sublittoral region. Laminaria digitata is fertile in summer whereas both other species are fertile in autumn/winter. To determine the light sensitivity of the propagules, zoospores of L. digitata, L. saccharina and L. hyperborea were exposed in the laboratory to different exposure times of photosynthetically active radiation (PAR; 400–700 nm), PAR + UVA radiation (UVAR; 320–400 nm) and PAR + UVAR + UVB radiation (UVBR; 280–320 nm). Optimum quantum yield of PSII and DNA damage were measured after exposure. Subsequently, recovery of photosynthetic efficiency and DNA damage repair, as well as germination rate were measured after 2 and 3 d cultivation in dim white light. Photosynthetic efficiency of all species was photoinhibited already at 20 µmol photons m−2 s−1 PAR, whereas UV radiation (UVR) had a significant additional effect on photoinhibition. Recovery of the PSII function was observed in all species but not in spores exposed to irradiation longer than 4 h of PAR + UVA + UVB and 8 h of PAR + UVA. The amount of UVB-induced DNA damage measured as cyclobutane–pyrimidine dimers (CPDs) increased with exposure time and highest damage was detected in the spores of lower subtidal L. hyperborea relative to the other two species. Significant removal of CPDs indicating repair of DNA damage was observed in all species after 2 d in low white light especially in the spores of upper subtidal L. digitata. Therefore, efficient DNA damage repair and recovery of PSII damage contributed to the germination success but not in spores exposed to 16 h of UVBR. UV absorption of zoospore suspension in L. digitata is based both on the absorption by the zoospores itself as well as by exudates in the medium. In contrast, the absorption of the zoospore suspension in L. saccharina and L. hyperborea is based predominantly on the absorption by the exudates in the medium. This study indicates that UVR sensitivity of zoospores is related to the seasonal zoospore production as well as the vertical distribution pattern of the large sporophytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2005.01288.x
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of light intensity and daylength on the β-dimethylsulphoniopropionate (DMSP) content of marine green macroalgae from Antarctica (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 13 (1990), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The β-dimethylsulphoniopropionate (DMSP) concentrations of 5 Antarctic green algae grown at 2, 30 and 55 μmol photons m−2 s−1 were determined during a period of one year, cultivated under fluctuating daylengths mimicking the conditions of the natural habitat at King George Island. Antarctica. The intracellular DMSP content of all species decreased simultaneously with decreasing daylengths and vice versa. Additionally, the DMSP level was affected by the light intensity: the higher the photon fluence rate the greater the algal DMSP concentration. Under conditions of darkness, there was a degradation of the DMSP pool in members of the Acrosiphoniales, while the DMSP content in members of the Ulvales did not change. The results indicate a light-dependent DMSP accumulation in algae. Therefore, they may help to explain the seasonal variability of DMSP and its cleavage product dimethylsulphide (DMS) in coastal waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1990.tb01991.x
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  • 3
    Electronic Resource
    Electronic Resource
    Incomplete turgor adjustment in Cladophora rupestrisunder fluctuating salinity regimes
    Amsterdam : Elsevier
    Estuarine, Coastal and Shelf Science 34 (1992), S. 413-427 
    Details
    ISSN: 0272-7714
    Keywords: Cladophora rupestris ; North Wales ; amino acids ; fluctuating salinity ; glycine betaine ; inorganic ions ; turgor pressure
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0272-7714(05)80079-4
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  • 4
    Electronic Resource
    Electronic Resource
    Calcium compartmentation in Antarctic brown algae
    Amsterdam : Elsevier
    Ultramicroscopy 32 (1990), S. 7-11 
    Details
    ISSN: 0304-3991
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Natural Sciences in General , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0304-3991(90)90087-3
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  • 5
    Electronic Resource
    Electronic Resource
    Seasonal changes in C, N and major organic compounds and their significance to morpho-functional processes in the endemic Antarctic brown alga Ascoseira mirabilis (1998)
    Springer
    Polar biology 19 (1998), S. 115-124 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The seasonal and intra-thallus variations in the contents of C, N, proteins and amino acids, as well as in the storage carbohydrates mannitol and laminaran, were measured in the endemic Antarctic brown alga Ascoseira mirabilis between September and February and related to seasonal changes in dark respiration and photosynthesis. Carbon contents between 31 and 37% DW were relatively constant throughout these months and no variations were detected among thallus regions. Nitrogen contents, by contrast, were higher in September/October (3.1% DW) and decreased in January and February (1.8% DW). In general, the basal regions had the lower N contents. Proteins reached maximum values of 13% DW in November and February and were inversely correlated to photosynthesis (net Pmax). The amino acid content was also higher in October and November (maxima close to 10% DW), but low between December and February (close to 5% DW), probably related to a seasonal pattern of N allocation in the alga. The storage carbohydrates mannitol and laminaran exhibited inverse seasonal changes: low mannitol values close to 5% DW in September were coupled with high laminaran contents varying between 7 and 15% DW. The existence of high laminaran contents in the distal blade region during September and February suggests that this compound was effectively accumulated in this region. The low P/R ratios in spring and the existence of a significant relationship between mannitol content and seasonal photosynthetic activity in the basal region appear to support the hypothesis of a possible utilization of carbohydrates to power growth in A. mirabilis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050222
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  • 6
    Electronic Resource
    Electronic Resource
    The life history of Porphyra endiviifolium from the South Shetland Islands, Antarctica (1998)
    Springer
    Polar biology 19 (1998), S. 257-263 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper describes the reproduction and life history of an intertidal species, Porphyra endiviifolium, from Antarctica. Field specimens were examined microscopically, prepared for electron microscopy and used to establish cultures. Wild populations comprised two kinds of leafy thalli, morphologically similar but distinguished by their mode of reproduction, either sexual or asexual. Carpospores from monoecious leafy gametophytes developed into conchocelis filaments in culture, and under “winter-spring” conditions these formed conchospores that germinated to produce leafy thalli. Monospores from asexual leafy thalli developed directly into two different forms of leafy thalli. Only one of the cultured morphotypes became fertile, reproducing asexually by monospores. We conclude that the phases of the life history of P. endiviifolium show different ecological strategies, the conchocelis phase reproducing in response to short days unlike the leafy thalli in which growth and reproduction respond primarily to irradiance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050243
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  • 7
    Electronic Resource
    Electronic Resource
    Recent advances in the investigation of Antarctic macroalgae (1996)
    Springer
    Polar biology 16 (1996), S. 231-240 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The paper summarizes our present knowledge of Antarctic macroalgae with regard to the following topics: explorative history of Antarctic macroalgae, the environment of macroalgae in the Antarctic, life histories and physiological anatomy, seasonal development, light demands and depth zonation, temperature demands and geographical distribution and the effect of desiccation, salinity and temperature on supra- and eulittoral algae. A baseline is visible, but much more work is necessary, especially to assess the susceptibility of macroalgae and coastal ecosystems in Antarctica to global climatic changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050049
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  • 8
    Electronic Resource
    Electronic Resource
    Seasonal photosynthetic performance of the endemic Antarctic red alga Palmaria decipiens (Reinsch) Ricker (1996)
    Springer
    Polar biology 16 (1996), S. 357-361 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A male gametophyte of the endemic Antarctic red macroalga Palmaria decipiens (Reinsch) Ricker was cultivated under fluctuating daylengths, simulating the seasonal changes at the site of collection (King George Island, Antarctica). The plant was maintained at 0±1°C, an irradiance of 25 μmol m-2 s-1 and under growth-saturating nutrient conditions. Samples were taken at intervals of 3–6 weeks to measure growth, photosynthesis, dark respiration and pigment content. The growth optimum in spring coincided with a higher photosynthetic activity. Whereas dark respiration was constantly low over the year, there was a rapid increase in maximum photosynthetic rate (Pmax) in conditions corresponding to September and October. This was correlated with a change in the initial slope (α) of the photosynthesis versus irradiance (P vs I) curve. Higher activity in photosynthesis mainly resulted from higher Chl a and phycobilin concentrations during Antarctic spring, an indication of an increase in absorption cross-section areas of photosynthetic reaction centres. These changes in physiology are discussed in relation to the seasonal growth “strategy” of the species, which is controlled by seasonal variation in daylength.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050065
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  • 9
    Electronic Resource
    Electronic Resource
    New records of temperate and sub-Antarctic marine benthic macroalgae from Antarctica (1997)
    Springer
    Polar biology 17 (1997), S. 141-149 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  During visits to several localities on the South Shetland Islands and the Antarctic Peninsula in summer 1994 we made collections of marine benthic algae. Among the algae we collected were three new records for Antarctica [Petalonia fascia (OF Müller) Kuntze; Enteromorpha intestinalis (L.) Nees; Rhodymenia subantarctica Ricker] and seven other species [Scytosiphon simplicissimus (Clemente) Cremades; Chordaria linearis (Hooker et Harvey) Cotton; Halopteris obovata (Hooker et Harvey) Sauvageau; Acrosiphonia arcta (Dillwyn) J. Agardh; Enteromorpha compressa (L.) Nees; Bangia atropurpurea (Roth) C. Agardh; Porphyra plocamiestris Ricker] that had been reported on only one or two previous occasions (or, in one case, three). The ten species detailed in this paper fall into two groups: four species previously known from sub-Antarctic islands and/or locations in southern South America, and six species having a wider distribution in temperate regions. We discuss the possibility that the less accessible subtidal habitats of some species may have prevented earlier discovery. Other species may be comparatively recent adventives, most likely introduced with shipping. In view of possible global climate changes, species of this latter group are regarded as suitable organisms for monitoring changes of water temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003000050116
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  • 10
    Electronic Resource
    Electronic Resource
    Seasonality of brown macroalgae from Antarctica—a long-term culture study under fluctuating Antarctic daylengths (1990)
    Springer
    Polar biology 10 (1990), S. 589-600 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The seasonal development of the endemic Antarctic Desmarestiales Himantothallus grandifolius, Phaeurus antarcticus, Desmarestia anceps, of a ligulate Desmarestia sp., of the Antarctic cold-temperate Adenocystis utricularis (Dictyosiphonales) and of the endemic Antarctic Ascoseira mirabilis (Ascoseirales) was monitored in a 2-year culture study under fluctuating daylengths mimicking the daylength conditions on King George Island (Antarctica). Temperature was kept constant at 0° C and nutrient levels were maintained at 0.6 moles m−3 nitrate and 0.025 moles m −3 phosphate. Sporophytes were initiated between (April-) June and July in all Desmarestiales. This event was controlled either by induction of gametophyte fertility (in H. grandifolius and D. anceps) or by induction of spore formation (in Desmarestia sp. and P. antarcticus). Young sporophytes of all species showed a growth optimum from September to December (-February). Desmarestia sp. and P. antarcticus produced spores and degenerated subsequently after one year of culture at ≥3 μmol photons m−2 s−1 or after 22 months of culture at 2 μmol m−2 s−1. In D. anceps spores were released without degeneration of the mother plants after 20 and 19 months of culture at 3 and 10 μolm−2 s−1, respectively. In H. grandifolius spore formation was not observed. Adult one year old plants of the latter two perennial species showed growth optima between September and November. Microthalli of A. utricularis were the dominant life phase of this alga in winter. Macrothalli started to develop from June onwards at ≥3 μmol m−2 s−1 or from August to September at 2 μmol m−2 s−1. Growth rates of macrothalli cultivated at ≥9 μmol m−2 s−1 showed a growth optimum from September to November. The macrothalli released spores from January to February. Macrothalli cultivated at ≥3 μmol m−2 s−1 maximally grew in January. They became fertile after almost 2 years of culture at 3 μmol m−2 s−1 and remained vegetative at 2 μmol m−2 s−1. A. mirabilis exhibited a prominent growth optimum from August to October, at photon fluence rates between 2 and 47 μmol m−2 s−1. A second optimum was evident from January to March in plants cultivated at ≥9 μmol m−2 s−1. The results closely correspond to available field data and indicate that the phenology of the studied species can be controlled in the laboratory solely by simulating Antarctic daylengths conditions. The light requirements for growth were very low in microthalli and in juvenile macrothalli and growth was mostly light saturated at 4–12 μmol m−2 s−1. Few-celled sporophytes of H. grandifolius and D. anceps tolerated at least 8 and 11 months of darkness. The minimum light demands for completion of the life cycle are 31.4 mol m−2 year−1 in Desmarestia sp., P. antarcticus and probably also in the 2 perennial Desmarestiales; 47.1 mol m−2 year−1 are needed in A. utricularis and probably also in A. mirabilis. These values predict a lower distribution limit of the investigated species at 53±23 m or 48±21 m in clear offshore waters and at 28±5 m or 26±5 m, respectively, in inshore fjords of the Antarctic Peninsula region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239370
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