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Nora Gómez - One of the best experts on this subject based on the ideXlab platform.
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Poblaciones de diatomeas planctónicas en una represa subtropical : Embalse Río III, Argentina
EDP Sciences, 2009Co-Authors: Nora GómezAbstract:En el presente trabajo se da a conocer la composición específica y la dinámica poblacional de las bacilario fitas halladas en el plancton limnético del Embalse Río III durante tres años y medio de muestreos. De los 32 taxones identificados las poblaciones más numerosas correspondieron a : Aulacoseira granulata, Aulacoseira granulata var. angustissima, Aulacoseira granulata var. angustissima f. spiralis, Aulacoseira lirata var. alpigena, Actinocyclus normanii f. subsalsa y Cymbella affinis. La flora diatomológica hallada en la represa resultó ser alcalófila, eutrófica y oligohalobia. Este grupo algal en reiteradas oportunidades dominó el fitoplancton del embalse generalmente en períodos otoñales y o invernales. La mezcla isotermal es uno de los principales condicionantes del incremento de las poblaciones de diatomeas en el embalse. Sin embargo A. granulata, que fue la bacilariofita más importante por su numerosidad, biomasa y persistencia en el tiempo, mostró desarrollos masivos durante dos períodos de est ratificaciín térmica
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Ecology and morphological variability of Aulacoseira granulata (Bacillariophyceae) in Spanish reservoirs
Journal of Plankton Research, 1995Co-Authors: Nora Gómez, Joan Lluís Riera, Sergi SabaterAbstract:The ecology of Aulacoseira (formerly Melosira) granulata and its different forms in ~30 reservoirs scattered throughout Spain has been analysed. Nutrient concentration explained a significant proportion of the variation in cell characteristics. In general, there is a tendency to find large cells with less densely areolated valves in nutrient-rich waters. Ecological differences between the type and its variety angustissima mainly concern calcium concentrations Aulacoseira granulata showed a unimodal response to the concentration of calcium, and preferred lower concentrations of calcium than the variety angustissima. The ecological differences between the a and -y forms (statuses) of A.granulata were also the object of our investigation. The y status occurred in all the reservoirs studied in summer, but in only 3 of 28 reservoirs studies in the overturn period. Light and turbulence explained the ecological differences observed between the two forms. The y status showed a certain preference for less turbulent waters compared with the a status, which is a more cosmopolitan form in its requirements.
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Poblaciones de diatomeas planctónicas en una represa subtropical : Embalse Río III, Argentina
Annales de Limnologie - International Journal of Limnology, 1991Co-Authors: Nora GómezAbstract:This paper deals with the species composition and the population dynamics of the diatoms that were found in the limnetic plankton of the Embalse Rio III over IhoII and a half years. 32 taxa were identified. The larger populations were : Aulacoseira liraia var. alpigena, Aulacoseira granulata, Aulacoseira granulata var. angustissima, Aulacoseira gra nulata var. angustissima f. spiralis, Actinocyclus normanii f. subsalsa and Cymbella affinis. The diatom flora found in Embalse Rio III were alkalophilous, otigohalobous eutrophic indicators. This algal group was often very dominant among the phytoplankton. This phenomenon usually took place during certain periods in autumn and winter. The iso thermal mixing is one of the principal factors for the increase of the diatom populations of the reservoir. However A. granulata was the dominant diatom in number, biomass and permanence ; this alga shows massive development during the two periods of thermal stratification.
S. I. Genkal - One of the best experts on this subject based on the ideXlab platform.
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Morphology, taxonomy and distribution of the rare species Aulacoseira cataractarum (Hustedt) Simonsen (Bacillariophyta) in Russia
Algologia, 2021Co-Authors: S. I. GenkalAbstract:This scanning electron microscopy study was undertaken to reanalyze frustule samples of the centric diatom algae Aulacoseira cataractarum, collected earlier from a swamp in the Uzon volcanic caldera (Kamchatka). This species, under the name of Melosira cataractarum, was reported before from a number of waterbodies in Russia. Later it was transferred to the genus Aulacoseira Thwaites – A. cataractarum (Hustedt) Simonsen (Simonsen, 1979), and then – to the genus Pseudostaurosira (A.Grunow) D.M.Williams & F.E.Round, under the name of P. seudostaurosira cataractarum (Hustedt) Wetzel, Morales et Ector. In this study we specify perforation of intercalary bands, the shape of the valves and spines as well as the number of valve face and mantle areolae per stria and their shape. Based on the original and published data an extended diagnosis of P. cataractarum is presented. Scanning electron microscope images of frustules of the centric diatom algae.
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Aulacoseira konstastinovii sp. nov. and Aulacoseira krylovii sp. nov. – two new centric diatoms from South-east Asia
Diatom Research, 2016Co-Authors: Anton Glushchenko, S. I. Genkal, Maxim KulikovskiyAbstract:Two new centric diatom species were found in samples collected from Vietnam and Cambodia, Aulacoseira konstantinovii sp. nov. and Aulacoseira krylovii sp. nov. The former differs from other members of the genus mainly by a characteristic strong undulation in the central area of the valve face. The latter is close to A. konstantinovii sp. nov. but differs in its valve face morphology and having fewer rimoportulae. The new species are illustrated by light microscope and scanning electron microscope images.
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Aulacoseira konstastinovii sp nov and Aulacoseira krylovii sp nov two new centric diatoms from south east asia
Diatom Research, 2016Co-Authors: Anton Glushchenko, S. I. Genkal, Maxim KulikovskiyAbstract:Two new centric diatom species were found in samples collected from Vietnam and Cambodia, Aulacoseira konstantinovii sp. nov. and Aulacoseira krylovii sp. nov. The former differs from other members of the genus mainly by a characteristic strong undulation in the central area of the valve face. The latter is close to A. konstantinovii sp. nov. but differs in its valve face morphology and having fewer rimoportulae. The new species are illustrated by light microscope and scanning electron microscope images.
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Centric diatoms in the southern part of the Republic of Karelia (Lakes of the Vendyurskaya group and Zaonezhiye)
Inland Water Biology, 2015Co-Authors: S. I. Genkal, T. A. ChekryzhevaAbstract:The first study of centric diatoms in the southern part of Karelia (Lake Zaonezhiye and lakes of the Vendyurskaya group) has been conducted using scanning electron microscopy. A total of 22 species from 7 genera have been detected: Aulacoseira (9), Cyclostephanos (1), Cyclotella (6), Discostella (1), Handmannia (1), Melosira (1), and Stephanodiscus (3). The species diversity of centric diatoms in the lakes under study varies from 8 to 14 taxa. Aulacoseira ambigua (Grunow) Simonsen, A. islandica (O. Müller) Simonsen, A. subborealis (Nygaard) Denus, Muylaert et Krammer, Cyclotella rossii Håkansson, and Discostella stelligera (Cleve et Grunow) Houk et Klee are the most widespread species. A. subborealis , a representative of the genus Aulacoseira , has been presented for the first time for the waterbodies of Karelia as an independent taxon of the species rank.
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Centric diatoms (Centrophyceae, Bacillariophyta) in watercourses and bodies of water in southeast of West Siberian Plain and Polar Ural
Contemporary Problems of Ecology, 2012Co-Authors: S. I. Genkal, R. E. RomanovAbstract:The study of phytoplankton from rivers and lakes in the southeastern part of the West Siberian Plain and the eastern macrosclope of the Polar Ural by scanning electron microscopy has revealed 25 taxa of Bacillariophyta from the class Centrophyceae (seven Aulacoseira, one Cyclostephanos, four Cyclotella, two Discostella, one Melosira, one Puncticulata, seven Stephanodiscus, and two Thalassiosira), including new species for the flora of the investigated bodies of water. The revision of the species composition of Centrophyceae in bodies of water and watercourses in the southeast part of the West Siberian Plain has allowed more exact identifying the taxonomic spectrum of this class. At present, the list includes 55 species, varieties and forms. During first studies conducted in rivers and lakes of the Lyapin River basin (Polar Ural) 16 species of centric diatoms that belong to the genera Aulacoseira, Cyclostephanos, Cyclotella, Discostella, Puncticulata, and Stephanodiscus have been recorded.
Eugene A Silow - One of the best experts on this subject based on the ideXlab platform.
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the melosira years of lake baikal winter environmental conditions at ice onset predict under ice algal blooms in spring
Limnology and Oceanography, 2015Co-Authors: Stephen L Katz, Lyubov R Izmesteva, Stephanie E Hampton, Ted Ozersky, Kirill Shchapov, Svetlana V Shimaraeva, Marianne V Moore, Eugene A SilowAbstract:Winter primary production in seasonally ice-covered lakes historically has not been well studied, but it is increasingly recognized as an important component of lake metabolism. Lake Baikal in Siberia is not only the World's oldest, deepest, and most biologically diverse lake, but also where large under-ice blooms of the diatom Aulacoseira baicalensis (formerly Melosira) occur in some years. The phenomenon of “Melosira years” is noteworthy both for the intensity of the diatom blooms, in which total under-ice production can be a majority of total annual production, and for the enigmatic regularity of their occurrence every 3–4 yr. The degree to which these episodic blooms might be controlled by external forcing and endogenous lake processes has been debated for decades. We used a 50-yr time series of phytoplankton observations to statistically model the occurrence of Aulacoseira blooms as a function of meteorological and climatological predictor variables. The results support the hypothesis that a confluence of meteorological conditions in the preceding fall season, which favor clear ice formation with minimal snow cover, also favor Aulacoseira blooms in the following spring. Further, we observe that this confluence of factors is related to relatively strong states of the Siberian High which, while not strictly periodic, do explain a significant fraction of the interannual bloom pattern. Finally, our analyses show that the timing of the peak abundance of A. baicalensis shifted 1.6 months later across the 50-yr time series, corresponding with the delay in ice-on timing that has been associated with climate change.
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The “Melosira years” of Lake Baikal: Winter environmental conditions at ice onset predict under‐ice algal blooms in spring
Limnology and Oceanography, 2015Co-Authors: Stephen L Katz, Stephanie E Hampton, Ted Ozersky, Kirill Shchapov, Svetlana V Shimaraeva, Lyubov R. Izmest'eva, Marianne V Moore, Eugene A SilowAbstract:Winter primary production in seasonally ice-covered lakes historically has not been well studied, but it is increasingly recognized as an important component of lake metabolism. Lake Baikal in Siberia is not only the World's oldest, deepest, and most biologically diverse lake, but also where large under-ice blooms of the diatom Aulacoseira baicalensis (formerly Melosira) occur in some years. The phenomenon of “Melosira years” is noteworthy both for the intensity of the diatom blooms, in which total under-ice production can be a majority of total annual production, and for the enigmatic regularity of their occurrence every 3–4 yr. The degree to which these episodic blooms might be controlled by external forcing and endogenous lake processes has been debated for decades. We used a 50-yr time series of phytoplankton observations to statistically model the occurrence of Aulacoseira blooms as a function of meteorological and climatological predictor variables. The results support the hypothesis that a confluence of meteorological conditions in the preceding fall season, which favor clear ice formation with minimal snow cover, also favor Aulacoseira blooms in the following spring. Further, we observe that this confluence of factors is related to relatively strong states of the Siberian High which, while not strictly periodic, do explain a significant fraction of the interannual bloom pattern. Finally, our analyses show that the timing of the peak abundance of A. baicalensis shifted 1.6 months later across the 50-yr time series, corresponding with the delay in ice-on timing that has been associated with climate change.
Edward C. Theriot - One of the best experts on this subject based on the ideXlab platform.
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phylogeny of Aulacoseira bacillariophyta based on molecules and morphology
Journal of Phycology, 2004Co-Authors: S. M. Edgar, Edward C. TheriotAbstract:The phylogeny of 67 populations representing 45 species of Aulacoseira Thwaites was estimated by maximum parsimony methods using a combination of nucleotide sequence data and qualitative and quantitative morphological characteristics of the silica cell wall gathered primarily from original observation by LM and SEM. A new type of character using continuous quantitative variables that describe the ontogenetic-allometric trajectories of cell wall characteristics over the life cycle (size range) of diatoms is introduced. In addition to the 45 Aulacoseira species, the phylogeny also incorporated one Miosira Krammer, Lange-Bertalot, and Schiller species and two outgroup species (Melosira varians Agardh and Stephanopyxis nipponica Gran & Yendo). Fifteen species, represented by 24 populations, also contained molecular data from the nuclear genome (18S rDNA), and 11 of these species (18 populations) contained data from the chloroplast genome (rbcL) as well, which were sequenced or downloaded from GenBank. The phylogeny of Aulacoseira is composed of five major clades: 1) an A. crenulata (Ehrenburg) Thwaites and A. italica (Ehrenburg) Simonsen clade, which is the most basal; 2) an A. granulata (Ehrenburg) Simonsen complex clade; 3) an A. ambigua (Grunow) Simonsen clade; 4) an A. subarctica (O. Muller) Haworth and A. distans (Ehrenburg) Simonsen clade; and 5) an A. islandica (O. Muller) Simonsen clade that also contained endemic species from Lake Baikal, Siberia and many extinct Aulacoseira taxa. Monophyly of Aulacoseira can only be achieved if Miosira is no longer given separate generic status.
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39 Phylogeny of Aulacoseira (bacillariophyta)
Journal of Phycology, 2003Co-Authors: S. M. Edgar, Edward C. TheriotAbstract:The phylogeny of 67 populations representing 45 species of Aulacoseira is estimated by maximum parsimony methods using a combination of nucleotide sequence data and qualitative and quantitative morphological characteristics of the silica cell wall gathered primarily from original observation by LM and SEM. A new type of character employing continuous quantitative variables describing the ontogenetic-allometric trajectories of cell wall characteristics over the life cycle (size range) of diatoms is introduced. In addition to the 45 Aulacoseira species, the phylogeny also incorporates one Alveolophora species, and two outgroup species (Melosira varians and Stephanopyxis cf. broschii). Fifteen species, represented by 24 populations, also contain molecular data from the chloroplast genome (rbcL) as well as the nuclear genome (18S), which were sequenced or downloaded from GenBank. The phylogeny of Aulacoseira is composed of five major clades: 1) an A. crenulata and A. italica clade, which is the most basal, 2) an A. subarctica and A. distans clade, 3) an A. granulata complex clade, 4) an A. ambigua clade, and 5) an A. islandica, A. skvorzowii, A. baicalensis, clade that also contains Alveolophora and many extinct Aulacoseira taxa. Monophyly of Aulacoseira is only achieved if Alveolophora, originally identified as Aulacoseira, is no longer given separate generic status.
Stephen L Katz - One of the best experts on this subject based on the ideXlab platform.
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the melosira years of lake baikal winter environmental conditions at ice onset predict under ice algal blooms in spring
Limnology and Oceanography, 2015Co-Authors: Stephen L Katz, Lyubov R Izmesteva, Stephanie E Hampton, Ted Ozersky, Kirill Shchapov, Svetlana V Shimaraeva, Marianne V Moore, Eugene A SilowAbstract:Winter primary production in seasonally ice-covered lakes historically has not been well studied, but it is increasingly recognized as an important component of lake metabolism. Lake Baikal in Siberia is not only the World's oldest, deepest, and most biologically diverse lake, but also where large under-ice blooms of the diatom Aulacoseira baicalensis (formerly Melosira) occur in some years. The phenomenon of “Melosira years” is noteworthy both for the intensity of the diatom blooms, in which total under-ice production can be a majority of total annual production, and for the enigmatic regularity of their occurrence every 3–4 yr. The degree to which these episodic blooms might be controlled by external forcing and endogenous lake processes has been debated for decades. We used a 50-yr time series of phytoplankton observations to statistically model the occurrence of Aulacoseira blooms as a function of meteorological and climatological predictor variables. The results support the hypothesis that a confluence of meteorological conditions in the preceding fall season, which favor clear ice formation with minimal snow cover, also favor Aulacoseira blooms in the following spring. Further, we observe that this confluence of factors is related to relatively strong states of the Siberian High which, while not strictly periodic, do explain a significant fraction of the interannual bloom pattern. Finally, our analyses show that the timing of the peak abundance of A. baicalensis shifted 1.6 months later across the 50-yr time series, corresponding with the delay in ice-on timing that has been associated with climate change.
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The “Melosira years” of Lake Baikal: Winter environmental conditions at ice onset predict under‐ice algal blooms in spring
Limnology and Oceanography, 2015Co-Authors: Stephen L Katz, Stephanie E Hampton, Ted Ozersky, Kirill Shchapov, Svetlana V Shimaraeva, Lyubov R. Izmest'eva, Marianne V Moore, Eugene A SilowAbstract:Winter primary production in seasonally ice-covered lakes historically has not been well studied, but it is increasingly recognized as an important component of lake metabolism. Lake Baikal in Siberia is not only the World's oldest, deepest, and most biologically diverse lake, but also where large under-ice blooms of the diatom Aulacoseira baicalensis (formerly Melosira) occur in some years. The phenomenon of “Melosira years” is noteworthy both for the intensity of the diatom blooms, in which total under-ice production can be a majority of total annual production, and for the enigmatic regularity of their occurrence every 3–4 yr. The degree to which these episodic blooms might be controlled by external forcing and endogenous lake processes has been debated for decades. We used a 50-yr time series of phytoplankton observations to statistically model the occurrence of Aulacoseira blooms as a function of meteorological and climatological predictor variables. The results support the hypothesis that a confluence of meteorological conditions in the preceding fall season, which favor clear ice formation with minimal snow cover, also favor Aulacoseira blooms in the following spring. Further, we observe that this confluence of factors is related to relatively strong states of the Siberian High which, while not strictly periodic, do explain a significant fraction of the interannual bloom pattern. Finally, our analyses show that the timing of the peak abundance of A. baicalensis shifted 1.6 months later across the 50-yr time series, corresponding with the delay in ice-on timing that has been associated with climate change.
