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Alaria esculenta

The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform

Christian Wiencke – 1st expert on this subject based on the ideXlab platform

  • Detection of parameteres influencing isotopic composition in kelps
    , 2018
    Co-Authors: Cornelia Buchholz, Benoit Lebreton, Inka Bartsch, Christian Wiencke

    Abstract:

    Kelp derived detritus is a potential food item at the base level of marine food webs. A good knowledge of the
    factors that influence stable isotope composition in kelps is essential for reliable food web models: The variation of stable isotope composition was analysed in three kelp species growing in Kongsfjorden, Svalbard. The parameters considered were depth, age, and algal anatomy: Between 15 and 2.5 m depth, towards higher photo
    fluence rate, Alaria esculenta was gradually enriched in δ13C while δ15N did not change. 2&3-year-old algae
    had significantly higher δ15N values in their blades than 5&6-year-old ones. A two factor analysis did not show any interactive effects between depth and age class. A. esculenta as well as Saccharina latissima and Laminaria digitata exhibited enrichment in heavy carbon isotopes in the blades.

  • Increased CO_2 modifies the carbon balance and the photosynthetic yield of two common Arctic brown seaweeds: Desmarestia aculeata and Alaria esculenta
    Polar Biology, 2016
    Co-Authors: Concepción Iñiguez, M. Rosario Lorenzo, F. Xavier Niell, Christian Wiencke, Raquel Carmona, F. J L Gordillo

    Abstract:

    Ocean acidification affects with special intensity Arctic ecosystems, being marine photosynthetic organisms a primary target, although the consequences of this process in the carbon fluxes of Arctic algae are still unknown. The alteration of the cellular carbon balance due to physiological acclimation to an increased CO_2 concentration (1300 ppm) in the common Arctic brown seaweeds Desmarestia aculeata and Alaria esculenta from Kongsfjorden (Svalbard) was analysed. Growth rate of D. aculeata was negatively affected by CO_2 enrichment, while A. esculenta was positively affected, as a result of a different reorganization of the cellular carbon budget in both species. Desmarestia aculeata showed increased respiration, enhanced accumulation of storage biomolecules and elevated release of dissolved organic carbon, whereas A. esculenta showed decreased respiration and lower accumulation of storage biomolecules. Gross photosynthesis (measured both as O_2 evolution and ^14C fixation) was not affected in any of them, suggesting that photosynthesis was already saturated at normal CO_2 conditions and did not participate in the acclimation response. However, electron transport rate changed in both species in opposite directions, indicating different energy requirements between treatments and species specificity. High CO_2 levels also affected the N-metabolism, and ^13C isotopic discrimination values from algal tissue pointed to a deactivation of carbon concentrating mechanisms. Since increased CO_2 has the potential to modify physiological mechanisms in different ways in the species studied, it is expected that this may lead to changes in the Arctic seaweed community, which may propagate to the rest of the food web.

  • Increased CO2 modifies the carbon balance and the photosynthetic yield of two common Arctic brown seaweeds: Desmarestia aculeata and Alaria esculenta
    Polar Biology, 2016
    Co-Authors: Concepción Iñiguez, Ricardo Carmona, M. Rosario Lorenzo, F. Xavier Niell, Christian Wiencke, F. J L Gordillo

    Abstract:

    Ocean acidification affects with special intensity Arctic ecosystems, being marine photosynthetic organisms a primary target, although the consequences of this process in the carbon fluxes of Arctic algae are still unknown. The alteration of the cellular carbon balance due to physiological acclimation to an increased CO2 concentration (1300 ppm) in the common Arctic brown seaweeds Desmarestia aculeata and Alaria esculenta from Kongsfjorden (Svalbard) was analysed. Growth rate of D. aculeata was negatively affected by CO2 enrichment, while A. esculenta was positively affected, as a result of a different reorganization of the cellular carbon budget in both species. Desmarestia aculeata showed increased respiration, enhanced accumulation of storage biomolecules and elevated release of dissolved organic carbon, whereas A. esculenta showed decreased respiration and lower accumulation of storage biomolecules. Gross photosynthesis (measured both as O2 evolution and 14C fixation) was not affected in any of them, suggesting that photosynthesis was already saturated at normal CO2 conditions and did not participate in the acclimation response. However, electron transport rate changed in both species in opposite directions, indicating different energy requirements between treatments and species specificity. High CO2 levels also affected the N-metabolism, and 13C isotopic discrimination values from algal tissue pointed to a deactivation of carbon concentrating mechanisms. Since increased CO2 has the potential to modify physiological mechanisms in different ways in the species studied, it is expected that this may lead to changes in the Arctic seaweed community, which may propagate to the rest of the food web.

Kai Bischof – 2nd expert on this subject based on the ideXlab platform

  • hyposaline conditions affect uv susceptibility in the arctic kelp Alaria esculenta phaeophyceae
    Phycologia, 2017
    Co-Authors: Karin Springer, Cornelius Lutz, Ursula Lutzmeindl, Angela Wendt, Kai Bischof

    Abstract:

    Abstract: The kelp Alaria esculenta represents a key species in high Arctic marine fjord ecosystems. However, the European Arctic is currently experiencing extensive environmental change. Glacial fjord systems, such as Kongsfjorden (Spitsbergen, Svalbard), are subjected to rising temperature, increased freshwater inflow from glaciers and melting snow and a changing ultraviolet (UV) radiation regime related to stratospheric ozone depletion. Thus, in addition to natural seasonality, sessile organisms require acclimation in order to adapt to an environment in transition. We examined the physiological and ultrastructural responses of A. esculenta to the combined exposure to hyposalinity and UV radiation. Photosynthetic quantum yield slightly decreased during a low-salinity treatment of 7 d. Exposure to UV radiation also lowered quantum yield, but specimens previously treated with hyposalinity were significantly less susceptible to UV than nontreated individuals. Concomitant with a loss of chlorophyll during t…

  • phlorotannin production and lipid oxidation as a potential protective function against high photosynthetically active and uv radiation in gametophytes of Alaria esculenta Alariales phaeophyceae
    Photochemistry and Photobiology, 2012
    Co-Authors: Franciska Steinhoff, Kai Bischof, Martin Graeve, Krzysztof Bartoszek, Christian Wiencke

    Abstract:

    Radiation damage can inter alia result in lipid peroxidation of macroalgal cell membranes. To prevent photo-oxidation within the cells, photoprotective substances such as phlorotannins are synthesized. In the present study, changes in total fatty acids (FA), FA composition and intra/extracellular phlorotannin contents were determined by gas chromatography and the Folin-Ciocalteu method to investigate the photoprotective potential of phlorotannins to prevent lipid peroxidation. Alaria esculenta juveniles (Phaeophyceae) were exposed over 20 days to high/low photosynthetically active radiation (PAR) in combination with UV radiation (UVR) in the treatments: PAB (low/high PAR + UV-B + UV-A), PA (low/high PAR + UV-A) or low/high PAR only. While extracellular phlorotannins increased after 10 days, intracellular phlorotannins increased with exposure time and PA and decreased under PAB. Interactive effects of time:radiation wavebands, time:PAR dose as well as radiation wavebands:PAR dose were observed. Low FA contents were detected in the PA and PAB treatments; interactive effects were observed between time:high PAR and PAB:high PAR. Total FA contents were correlated to extra/intracellular phlorotannin contents. Our results suggest that phlorotannins might play a role in intra/extracellular protection by absorption and oxidation processes. Changes in FA content/composition upon UVR and high PAR might be considered as an adaptive mechanism of the A. esculenta juveniles subjected to variations in solar irradiance.

  • UV-radiation and elevated temperatures induce formation of reactive oxygen species in gametophytes of cold-temperate/Arctic kelps (Laminariales, Phaeophyceae)
    Phycological Research, 2011
    Co-Authors: Ruth Muller, Christian Wiencke, Christine Desel, Franciska S. Steinhoff, Kai Bischof

    Abstract:

    Enhanced UV-radiation (UVR) through stratospheric ozone depletion and global warming are crucial stressors
    to marine macroalgae. Damages may arise through formation of reactive oxygen species (ROS) in gametophytes
    of ecologically important kelps, brown algae of the order Laminariales, Such stress-induced damages may have a negative impact on their fitness and further impact their following life stages. In our study, gametophytes
    of three kelp species Alaria esculenta (L.) Grev., Laminaria digitata (Huds.) Lamour., Saccharina
    latissima (L.) Lane, Mayes, Druehl, Saunders from the Arctic, and of L. hyperborea (Gunnerus) Foslie from the
    North Sea were exposed to photosynthetically active radiation, UV-A, and UV-B radiation and four temperatures
    (2–18°C). ROS are formed predominantly in the peripheral cytoplasm and in chloroplasts especially
    after exposure to UVR. Superoxide (O2*-) is additionally formed in small, globular cytoplasmic structures,
    possibly mitochondria. In the surrounding medium O2*–concentration increased markedly at elevated temperatures and under UV stress in some cases. Ultrastructural damage was negligible pointing to a high
    stress tolerance of this developmental stage. Our data indicate that stress tolerant gametophytes of three Arctic kelp species should sustain their crucial function as seed bank for kelp populations even under prospective rising environmental perturbations.

Michael D Guiry – 3rd expert on this subject based on the ideXlab platform

  • are north atlantic Alaria esculenta and a grandifolia Alariaceae phaeophyceae conspecific
    European Journal of Phycology, 2001
    Co-Authors: Stefan Kraan, Jan Rueness, Michael D Guiry

    Abstract:

    Alaria (Alariaceae, Phaeophyceae) is a common genus of kelps in the northern hemisphere. Fourteen species are currently recognized, of which three, Alaria esculenta (L.) Greville, A. pylaii (Bory de Saint-Vincent) Greville and A. grandifolia J. Agardh, are reported for the coldtemperate North Atlantic Ocean. Alaria esculenta, the type species described originally from the North Atlantic, exhibits a range of biogeographically correlated morphotypes suggesting the possibility of multiple species, subspecies or hybrids. In Ireland we discovered an A. esculenta population with unusually long stipes resembling the type specimen of A. grandifolia described from Spitsbergen by J. Agardh in 1872. These and other plants of A. esculenta from Ireland were compared with plants from Spitsbergen fitting the description of A. grandifolia, using sexual hybridization, relative growth rate measurements and DNA sequence comparisons. Complete interfertility was observed between the different isolates. Three nucleotide substi…

  • The edible brown seaweed Alaria esculenta (Phaeophyceae, Laminariales): hybridization, growth and genetic comparisons of six Irish populations
    Journal of Applied Phycology, 2000
    Co-Authors: Stefan Kraan, Adriana Verges Tramullas, Michael D Guiry

    Abstract:

    Alaria esculenta populations from six differentgeographical locations on the Irish coast wereexamined for hybridization abilities, growth rates andgenetic make-up with a view towards identifying afast-growing strain suitable for aquaculture.Hybridization experiments under laboratory conditionswith the three most geographically dispersedpopulations showed that all cross combinations wereinterfertile, although differences were found insurvival, and in blade and hapteron morphology. Acomparison of relative growth rates showed significantdifferences amongst the self-crosses and hybrids. Thedata of the hybridization experiments and growth ratesunder laboratory conditions show that the bestpopulation for the purpose of seaweed aquaculture arethe Slea Head and Corbet Head self-crosses and theirhybrids. Genetic fingerprinting of the internaltranscribed spacer of the ribosomal DNA of five A. esculenta isolates from geographically separatedpopulations in Ireland revealed no restriction lengthpolymorphisms between the tested isolates and showthat the A. esculenta populations around theIrish coast are clearly genetically homogenous inrespect of the DNA region examined. The geneticanalysis, interfertility of the populations,morphology and growth rates are discussed with a viewto potential cultivation.

  • molecular and morphological character inheritance in hybrids of Alaria esculenta and a praelonga Alariaceae phaeophyceae
    Phycologia, 2000
    Co-Authors: Stefan Kraan, Michael D Guiry

    Abstract:

    Abstract Hybridization of Alaria esculenta and A. praelonga (Phaeophyceae. Laminariales, Alariaceae) resulted in successful and healthy progeny. Morphological characters, relative growth rates and Rubisco spacer sequences of hybrids were compared with the parental plants. The results show that hybrids inherit the morphological characters from the A. praelonga gametophytes, indicating that these characters are not sex-linked and are dominant. The relative growth rates were significantly different among the F1, with the A. esculenta self-cross progeny showing the fastest relative growth rate for length compared to the other cross combinations. The A. praelonga self-cross progeny also grew significantly faster than the progeny from hybrid crosses, which did not differ significantly from each other. The A. esculenta and A. praelonga self-cross F1 did not differ significantly in relative growth rate for width. Hybrid progeny showed a significant slower relative growth rate for width, compared to the A. esculen…