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Christian Wiencke - One of the best experts on this subject based on the ideXlab platform.
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Detection of parameteres influencing isotopic composition in kelps
2018Co-Authors: Cornelia Buchholz, Benoit Lebreton, Inka Bartsch, Christian WienckeAbstract: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.
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Increased CO2 modifies the carbon balance and the photosynthetic yield of two common Arctic brown seaweeds: Desmarestia aculeata and Alaria esculenta
Polar Biology, 2016Co-Authors: Concepción Iñiguez, M. Rosario Lorenzo, F. Xavier Niell, Christian Wiencke, Ricardo Carmona, F. J L GordilloAbstract: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.
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Increased CO_2 modifies the carbon balance and the photosynthetic yield of two common Arctic brown seaweeds: Desmarestia aculeata and Alaria esculenta
Polar Biology, 2016Co-Authors: Concepción Iñiguez, M. Rosario Lorenzo, F. Xavier Niell, Christian Wiencke, Raquel Carmona, F. J L GordilloAbstract: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.
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Effects of simultaneous increase in temperature and ocean acidification on biochemical composition and photosynthetic performance of common macroalgae from Kongsfjorden (Svalbard)
Polar Biology, 2016Co-Authors: F. J L Gordillo, Christian Wiencke, Raquel Carmona, Benjamín Viñegla, Carlos JiménezAbstract:Increased temperature and ocean acidification are two main factors threatening Arctic coastal ecosystems. To explore the consequences of increased average temperature and ocean acidification in Kongsfjorden, the performance of six common species of macroalgae, the chlorophyte Monostroma arcticum , the rhodophytes Phycodrys rubens , and Ptilota plumosa , and the phaeophytes Alaria esculenta , Desmarestia aculeata and Saccorhiza dermatodea , was tested after 9 days of culture at 4 and 10 °C in combination with current (ca. 390 ppmv) and future (1000 ppmv) levels of atmospheric CO_2 under solar radiation in summer. Temperature affected mainly the photosynthetic performance as measured by PAM fluorescence, particularly the initial slope ( α ) of ETR curves, the light saturation parameter ( E _ k ), and F _ v / F _ m values, as well as the protein content, especially in the phaeophytes. On the other hand, CO_2 affected mainly the internal accumulation of carbohydrates and lipids. The C:N balance was largely unaffected. External carbonic anhydrase activity was not inhibited at high CO_2, and nitrate reductase activity remained unaffected. The resulting growth rate was not altered by treatments in three out of the six species studied. On the other hand, P. rubens showed a positive effect of increasing temperature, D. aculeata was negatively influenced by CO_2, and S. dermatodea was positively affected by CO_2. Significant interactions between CO_2 and temperature were found in 20 % of the analyses. Whether additive or synergistic, the co-occurrence of a higher temperature with other stressors such as elevated CO_2 increases the probability of community changes by modifying the performance of these species.
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Working on a baseline for the Kongsfjorden food web: production and properties of macroalgal particulate organic matter (POM)
Polar Biology, 2015Co-Authors: Cornelia Buchholz, Christian WienckeAbstract:Macroalgae, in particular kelps, produce a large amount of biomass in Kongsfjorden, which is to a great extent released into the water in an annual cycle. As an example, the brown alga Alaria esculenta loses its blade gradually, 3 ± 0.8 % of the blade area per day (August 2012), thereby adding to the pool of particulate organic matter (POM) in the fjord. Upon release small thallus pieces are “aging” in that they are prone to leaching and serving as substrate for microorganisms, thus turning into palatable food for suspension and bottom feeders. In order to define a macroalgal baseline for the Kongsfjorden food web, stable isotopes δ14C and δ15N were measured in individuals of A. esculenta, Saccharina latissima and Laminaria digitata directly sampled after collection and in artificially produced POM (aPOM) of A. esculenta that was allowed to age under experimental conditions. In aPOM from this species sampled in August 2012 the C/N ratios decreased between d1 and d8 of a 14-day culture period in parallel to the fading photosynthetic activity of the algal fragments as demonstrated by use of an Imaging-PAM. Microscopic observations of the aPOM in August 2012 and 2013 revealed the frequent occurrence of small brown algal endo- and epiphytes. First feeding experiments with Mysis oculata (Mysids) and Hiatella arctica (Bivalves) showed that these species can ingest macroalgal POM. The importance of kelp-derived POM for the food web is subject of the current research.
Kai Bischof - One of the best experts on this subject based on the ideXlab platform.
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hyposaline conditions affect uv susceptibility in the arctic kelp Alaria esculenta phaeophyceae
Phycologia, 2017Co-Authors: Karin Springer, Cornelius Lutz, Ursula Lutzmeindl, Angela Wendt, Kai BischofAbstract: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...
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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, 2012Co-Authors: Franciska Steinhoff, Kai Bischof, Martin Graeve, Krzysztof Bartoszek, Christian WienckeAbstract: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.
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UV-radiation and elevated temperatures induce formation of reactive oxygen species in gametophytes of cold-temperate/Arctic kelps (Laminariales, Phaeophyceae)
Phycological Research, 2011Co-Authors: Ruth Muller, Christian Wiencke, Christine Desel, Franciska S. Steinhoff, Kai BischofAbstract: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.
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interactive effects of radiation temperature and salinity on different life history stages of the arctic kelp Alaria esculenta phaeophyceae
Oecologia, 2009Co-Authors: Jana Fredersdorf, Christian Wiencke, Ruth Muller, Susanne Becker, Kai BischofAbstract:To estimate the potential effects of climate change on polar marine macroalgae, studies on interactive stress effects of multiple climate-related parameters are essential. Interactions of temperature, radiation and salinity on two different life history stages of Alaria esculenta (L.) Greville from the Kongsfjord (Spitsbergen) were investigated for the first time within this study. Adult macroscopic sporophytes of A. esculenta were exposed to different temperatures between 4 and 21°C combined with artificial irradiation conditions [photosynthetically active radiation, ultraviolet (UV) radiation: UV-A/UV-B, first experiment] and with different salinities [34, 28, 20 practical salinity units (p.s.u.)¸ second experiment]. Effects of photosynthetic activity were determined by measuring variable chlorophyll fluorescence of photosystem II. Germination success of young microscopic zoospores of A. esculenta was studied under multifactorial stress. Zoospore suspensions were exposed to the three different salinities and irradiation conditions at four temperatures between 2 and 16°C. Overall, A. esculenta exhibited a highly stage-specific susceptibility towards the experimental treatments. In both experiments using sporophytes, photosynthetic activity showed significant temperature effects and only very few significant radiation and salinity effects. Microscopic stages of A. esculenta were shown to be more sensitive than the adult macroscopic stages, since germination capacity of zoospores was significantly affected by temperature and salinity changes, and interactions of both. These results suggest that multiple stress factors interact synergistically. Temperature seems to be a predominant environmental parameter for the kelp A. esculenta. Overall, A. esculenta proved to be relatively tolerant and adaptable to increasing temperature and UV radiation, as well as to diluted salinities, but only up to a specific limit.
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Zoospores of Three Arctic Laminariales Under Different UV Radiation and Temperature Conditions: Exceptional Spectral Absorbance Properties and Lack of Phlorotannin Induction
Photochemistry and Photobiology, 2009Co-Authors: Ruth Muller, Christian Wiencke, Kai Bischof, Bernd KrockAbstract:Phlorotannins have often been considered to act as UV-protective compounds in zoospores of brown algae. However, only the absorption characteristics of zoospores under UV exposure have been determined and no data are available on the actual content of phlorotannins or on temperature–UV interactions. Therefore, we determined the absorbance spectra and the phlorotannin contents in zoospore suspensions of three Arctic species (Saccharina latissima, Laminaria digitata, Alaria esculenta), and in the media surrounding zoospores after exposure to different radiation (400–700, 320–700, 295–700 nm) and temperature (2–18°C) conditions for 8 h. Absorption typical of phlorotannins with a maximum at 276 nm was monitored in zoospore suspensions as well as in the media surrounding zoospores, but the results depended strongly on radiation treatments and on zoospore densities. Surprisingly, the content of UV-absorbing phlorotannins subsequent to different exposures did not change in any of the three species. The observed exceptional absorption properties could, therefore, not be related to phlorotannin contents. These findings are discussed in light of a strong phlorotannin investment from sporophytes during spore release and a minor UV-protective role of phlorotannins for zoospores of Arctic kelp species.
Michael D Guiry - One of the best experts on this subject based on the ideXlab platform.
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are north atlantic Alaria esculenta and a grandifolia Alariaceae phaeophyceae conspecific
European Journal of Phycology, 2001Co-Authors: Stefan Kraan, Jan Rueness, Michael D GuiryAbstract: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...
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The edible brown seaweed Alaria esculenta (Phaeophyceae, Laminariales): hybridization, growth and genetic comparisons of six Irish populations
Journal of Applied Phycology, 2000Co-Authors: Stefan Kraan, Adriana Verges Tramullas, Michael D GuiryAbstract: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.
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molecular and morphological character inheritance in hybrids of Alaria esculenta and a praelonga Alariaceae phaeophyceae
Phycologia, 2000Co-Authors: Stefan Kraan, Michael D GuiryAbstract: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...
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Sexual hybridization experiments and phylogenetic relationships as inferred from rubisco spacer sequences in the genus Alaria (phaeophyceae)
Journal of Phycology, 2000Co-Authors: Stefan Kraan, Michael D GuiryAbstract:Alaria (Alariaceae, Phaeophyceae) is a common genus of kelps generally found in the lower intertidal and shallow subtidal regions of rocky shores subject to strong wave exposure. Fourteen species are currently recognized, of which 11 are found in the cold‐ temperate North Pacific Ocean. Alaria esculenta (L.) Greville, the type species described from the North Atlantic, exhibits a range of biogeographically correlated morphotypes indicating the possibility of multiple species, subspecies, and/or hybrids. This has led to an unstable taxonomy. We compared five species from the Atlantic and Pacific, including six North Atlantic isolates of A. esculenta. Phylogenetic analyses based on Rubisco spacer sequences resulted in a well-resolved topology of these five species, but did not distinguish between the six biogeographic isolates of A. esculenta. Laboratory hybridization experiments among four A. esculenta isolates showed partial intrafertility. Among five tested Alaria species, interfertility as well as fertility barriers were encountered, inconsistent with reproductive isolation. The data reject both a biological and morphological species concept and support only a phylogenetic species concept for Alaria , demonstrating that morphological variation has evolved independently of molecular variation in the genes under investigation in the species of the genus Alaria.
Joanna M Kain - One of the best experts on this subject based on the ideXlab platform.
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Effect of photon irradiance and photoperiod on young sporophytes of four species of the Laminariales
European Journal of Phycology, 1996Co-Authors: Joanna M KainAbstract:Four kelp species (Alaria esculenta, Laminaria digitata, L. hyperborea and L. saccharina) were cultured in the laboratory and pretreated so that gametophytes became mature and sporophytes were produced. Young sporophytes less than 3 weeks old were exposed to various light conditions and their survival or relative growth rate in length (R L), and width (R W) in one experiment, determined. Sporophytes of L. digitata survived poorly in the dark compared with L. hyperborea. The minimum photon irradiance allowing growth in L. hyperborea was about 1 μmol m-2 s-1; 1–2 μmol m-2 s-2 sustained growth in all the species. The growth of all four species was saturated at 20–30 μmol m-2 s-1 of continuous photon irradiance. In shorter daylengths the growth rate was lower both below and above light saturation. Above saturation the growth was considerably faster than would be expected if no photosynthetic products were carried over from the light to the dark period. There was evidence that 2–3 times as much light was neces...
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blue light photoreactivation in ultraviolet irradiated young sporophytes of Alaria esculenta and laminaria saccharina phaeophyta 1
Journal of Phycology, 1993Co-Authors: Joanna M KainAbstract:Exposure of ultraviolet (UV)-irradiated young sporophytes of Alaria esculenta (L.) Grev. and Laminaria saccharina (L.) Lamour. to visible light resulted in recovery from UV damage that would otherwise cause much higher mortality. For this photoreactivation, blue light was highly effective, whereas negligible reactivation was produced in green or red light. The blue quantum requirements for a 50% response were 1.9 mol.m −2 in A. esculenta and 1.2 mol.m −2 in L. saccharina, which were comparable to those reported for other blue light responses requiring high energy found in brown algae
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BLUE LIGHT PHOTOREACTIVATION IN ULTRAVIOLET‐IRRADIATED YOUNG SPOROPHYTES OF Alaria esculenta AND LAMINARIA SACCHARINA (PHAEOPHYTA)1
Journal of Phycology, 1993Co-Authors: Joanna M KainAbstract:Exposure of ultraviolet (UV)-irradiated young sporophytes of Alaria esculenta (L.) Grev. and Laminaria saccharina (L.) Lamour. to visible light resulted in recovery from UV damage that would otherwise cause much higher mortality. For this photoreactivation, blue light was highly effective, whereas negligible reactivation was produced in green or red light. The blue quantum requirements for a 50% response were 1.9 mol.m −2 in A. esculenta and 1.2 mol.m −2 in L. saccharina, which were comparable to those reported for other blue light responses requiring high energy found in brown algae
Stefan Kraan - One of the best experts on this subject based on the ideXlab platform.
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Undaria marching on; late arrival in the Republic of Ireland
Journal of Applied Phycology, 2016Co-Authors: Stefan KraanAbstract:The Asian invasive brown seaweed Undaria pinnatifida was found for the first time in the Republic of Ireland in Kilmore Quay in Co. Wexford in July 2016. As this brown kelp is of considerable economic importance and is cultivated in Asia as well as in Europe, it opens up the discussion if this invasive species is socially acceptable to be cultivated in the Republic of Ireland for food and other purposes. This paper briefly examines the global economic importance, cultivation aspects compared to the European native equivalents such as Alaria esculenta and Saccharina latissima, cultivation yield, economic considerations and the ecological impact of the spread of Undaria into non-native areas. Based on the information and facts presented, it is concluded that Undaria from a physical, social and economic point of view can be cultivated in Ireland.
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are north atlantic Alaria esculenta and a grandifolia Alariaceae phaeophyceae conspecific
European Journal of Phycology, 2001Co-Authors: Stefan Kraan, Jan Rueness, Michael D GuiryAbstract: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...
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The edible brown seaweed Alaria esculenta (Phaeophyceae, Laminariales): hybridization, growth and genetic comparisons of six Irish populations
Journal of Applied Phycology, 2000Co-Authors: Stefan Kraan, Adriana Verges Tramullas, Michael D GuiryAbstract: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.
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molecular and morphological character inheritance in hybrids of Alaria esculenta and a praelonga Alariaceae phaeophyceae
Phycologia, 2000Co-Authors: Stefan Kraan, Michael D GuiryAbstract: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...
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Sexual hybridization experiments and phylogenetic relationships as inferred from rubisco spacer sequences in the genus Alaria (phaeophyceae)
Journal of Phycology, 2000Co-Authors: Stefan Kraan, Michael D GuiryAbstract:Alaria (Alariaceae, Phaeophyceae) is a common genus of kelps generally found in the lower intertidal and shallow subtidal regions of rocky shores subject to strong wave exposure. Fourteen species are currently recognized, of which 11 are found in the cold‐ temperate North Pacific Ocean. Alaria esculenta (L.) Greville, the type species described from the North Atlantic, exhibits a range of biogeographically correlated morphotypes indicating the possibility of multiple species, subspecies, and/or hybrids. This has led to an unstable taxonomy. We compared five species from the Atlantic and Pacific, including six North Atlantic isolates of A. esculenta. Phylogenetic analyses based on Rubisco spacer sequences resulted in a well-resolved topology of these five species, but did not distinguish between the six biogeographic isolates of A. esculenta. Laboratory hybridization experiments among four A. esculenta isolates showed partial intrafertility. Among five tested Alaria species, interfertility as well as fertility barriers were encountered, inconsistent with reproductive isolation. The data reject both a biological and morphological species concept and support only a phylogenetic species concept for Alaria , demonstrating that morphological variation has evolved independently of molecular variation in the genes under investigation in the species of the genus Alaria.
