Estudio taxonómico preliminar de la ficoflora planctónica en la zona aluvial del Río Colorado (La Pampa, Argentina)

This work is part of a larger project on the study of algal biodiversity of a lotic system in La Pampa province. In this first stage we analyze the algal flora of samples collected during the summer season and autumn of 2010. The study area is located in the floodplain of the Colorado River, the natural boundary between the provinces of La Pampa and Río Negro at its intersection with Provincial Route 11 (Department Lihuel Calel). The methodology used in the collection followed the standard parameters for lotic environments. The samples were fixed with 4% formaldehyde and deposited in the herbarium of the Faculty of Agronomy (UNLPam) under the symbol SRFA. The preliminary results of the algal flora of summer and autumn shows 64 taxa, of which 26.5% corresponds to Cyanophyceae, 36% to Chlorophyceae and Bacillariophyceae, and 1.5% to Dinophyceae. During the summer the class Chlorophyceae species contributed 40% and fall did the Bacillariophyceae with 43.7%. The 37.5% of the registered species were common to both seasons.Instituto de Limnología "Raúl A. Ringuelet

Estudio taxonómico preliminar de la ficoflora planctónica en la zona aluvial del Río Colorado (La Pampa, Argentina)

This work is part of a larger project on the study of algal biodiversity of a lotic system in La Pampa province. In this first stage we analyze the algal flora of samples collected during the summer season and autumn of 2010. The study area is located in the floodplain of the Colorado River, the natural boundary between the provinces of La Pampa and Río Negro at its intersection with Provincial Route 11 (Department Lihuel Calel). The methodology used in the collection followed the standard parameters for lotic environments. The samples were fixed with 4% formaldehyde and deposited in the herbarium of the Faculty of Agronomy (UNLPam) under the symbol SRFA. The preliminary results of the algal flora of summer and autumn shows 64 taxa, of which 26.5% corresponds to Cyanophyceae, 36% to Chlorophyceae and Bacillariophyceae, and 1.5% to Dinophyceae. During the summer the class Chlorophyceae species contributed 40% and fall did the Bacillariophyceae with 43.7%. The 37.5% of the registered species were common to both seasons.Instituto de Limnología "Raúl A. Ringuelet

Variación estacional de la comunidad microfitoplanctónica del curso medio del río Colorado (La Pampa, Argentina)

We analyzed the seasonal variation of the phycoflora in the Colorado River alluvium with the aim of expanding knowledge of algal biodiversity in lotic environments of the province of La Pampa. The study area is located in the middle basin of the Colorado River (38º 49’ S and 64º 59’ W), Lihue Calel, which is the natural limit between La Pampa and Río Negro provinces. The site is located 122 meters above sea level with a channel width of 113 m. Samples were collected according to the standard methodology for lotic environments during autumn 2010 - autumn 2011. Physicochemical parameters were measured in situ. Water temperature ranged from 3.4 to 24°C for winter and summer respectively. The pH ranged between 8.1 and 8.6, the conductivity varied between 938 and 1950 μS cm-1 and the flow velocity ranged between 0.5 and 0.9 m sec-1. Phytoplankton samples were deposited in the Herbarium SRFA (UNLPam). 163 taxa were identified mostly belonging to Bacillariophyceae (42%). Chlorophyceae contributed 36%, while 17% Cyanobacteria, Euglenophyceae, Dinophyceae, Rhodophyceae and Xanthophyceae were found as companions taxa. The similarity of biodiversity in the alluvial section of the Colorado River is almost 70% as observed in the dendrogram resulting from the application of the Bray Curtis index, and grouped according to a seasonal sampling sequence.Facultad de Ciencias Naturales y Muse

Variación estacional de la comunidad microfitoplanctónica del curso medio del río Colorado (La Pampa, Argentina)

We analyzed the seasonal variation of the phycoflora in the Colorado River alluvium with the aim of expanding knowledge of algal biodiversity in lotic environments of the province of La Pampa. The study area is located in the middle basin of the Colorado River (38º 49’ S and 64º 59’ W), Lihue Calel, which is the natural limit between La Pampa and Río Negro provinces. The site is located 122 meters above sea level with a channel width of 113 m. Samples were collected according to the standard methodology for lotic environments during autumn 2010 - autumn 2011. Physicochemical parameters were measured in situ. Water temperature ranged from 3.4 to 24°C for winter and summer respectively. The pH ranged between 8.1 and 8.6, the conductivity varied between 938 and 1950 μS cm-1 and the flow velocity ranged between 0.5 and 0.9 m sec-1. Phytoplankton samples were deposited in the Herbarium SRFA (UNLPam). 163 taxa were identified mostly belonging to Bacillariophyceae (42%). Chlorophyceae contributed 36%, while 17% Cyanobacteria, Euglenophyceae, Dinophyceae, Rhodophyceae and Xanthophyceae were found as companions taxa. The similarity of biodiversity in the alluvial section of the Colorado River is almost 70% as observed in the dendrogram resulting from the application of the Bray Curtis index, and grouped according to a seasonal sampling sequence.Facultad de Ciencias Naturales y Muse

Variación estacional de la comunidad microfitoplanctónica del curso medio del río Colorado (La Pampa, Argentina)

We analyzed the seasonal variation of the phycoflora in the Colorado River alluvium with the aim of expanding knowledge of algal biodiversity in lotic environments of the province of La Pampa. The study area is located in the middle basin of the Colorado River (38º 49’ S and 64º 59’ W), Lihue Calel, which is the natural limit between La Pampa and Río Negro provinces. The site is located 122 meters above sea level with a channel width of 113 m. Samples were collected according to the standard methodology for lotic environments during autumn 2010 - autumn 2011. Physicochemical parameters were measured in situ. Water temperature ranged from 3.4 to 24°C for winter and summer respectively. The pH ranged between 8.1 and 8.6, the conductivity varied between 938 and 1950 μS cm-1 and the flow velocity ranged between 0.5 and 0.9 m sec-1. Phytoplankton samples were deposited in the Herbarium SRFA (UNLPam). 163 taxa were identified mostly belonging to Bacillariophyceae (42%). Chlorophyceae contributed 36%, while 17% Cyanobacteria, Euglenophyceae, Dinophyceae, Rhodophyceae and Xanthophyceae were found as companions taxa. The similarity of biodiversity in the alluvial section of the Colorado River is almost 70% as observed in the dendrogram resulting from the application of the Bray Curtis index, and grouped according to a seasonal sampling sequence.Facultad de Ciencias Naturales y Muse

Contribución al conocimiento ficológico y calidad de agua de la laguna La Arocena (pcia. de La Pampa, Argentina)

This work is part of an overall project that includes the study of the dynamics of algae in aquatic ecosystems in the province of La Pampa (Argentina). The aim of this contribution is to cite the species recorded for the Arocena and determine the saprobic and water quality of the lake. From October 2006 to August 2007 these were seasonal sampled in the Arocena shallow lake (Maracó Department), La Pampa. The samples were collected at six prefixed sites with phytoplankton net opening of 25 microns mesh. The physico-chemical variables (T °C, pH, conductivity, nitrites, nitrates, dissolved oxygen, among others) were obtained using portable sensors and subsequent laboratory techniques. These parameters provided an autecological characterization of the species studied and some of them extended the range of tolerance to the literature. Of all the species listed (251), 40% were Chlorophyceae, 32% Bacillariophyceae, 22% Cyanophyceae, Euglenophyceae 3.5% and 2.5% remaining Chrysophyceae, Xanthophyceae, Cryptophyceae and Dinophyceae. The determined state was β mesosaprobic and the water quality was α mesosaprobic.Instituto de Limnología "Raúl A. Ringuelet

Lista taxonómica preliminar del fitoplancton del Río Colorado en Villa Vieja, (dpto. Puelén, La Pampa, Argentina)

This work presents preliminary taxonomic information of the phytoplankton community of the Colorado river, the natural boundary between the provinces of La Pampa and Río Negro. With the objective to know and categorize the algal communities of phytoplankton, samples were collected in Villa Vieja, on the left bank. The study area is located at 38º 14’ 55’’ lat. S; 67° 11’ 49’’ long. W at 232 msnm, downstream of Embalse Casa de Piedra dam. The results correspond to samples taken in February 2010, the period of maximum flow. The samples were collected with plankton net of 20 microns aperture observed in vivo and then fixed in formalin (4%). For studies of diatoms aliquots of the samples and subsequent treatment for the removal of organic matter and making diatom preparations. The physicochemical and environmental were recorded in situ by using portable sensors and subsequent laboratory techniques. Of all taxa identified to the present functional groups recorded were: 32.7% Bacillariophyceae, Chlorophyceae 44.3%, Cyanophyceae 11.5% and 11.5% other algae remaining partners, including Euglenophyceae.Instituto de Limnología "Raúl A. Ringuelet

Lista taxonómica preliminar del fitoplancton del Río Colorado en Villa Vieja, (dpto. Puelén, La Pampa, Argentina)

This work presents preliminary taxonomic information of the phytoplankton community of the Colorado river, the natural boundary between the provinces of La Pampa and Río Negro. With the objective to know and categorize the algal communities of phytoplankton, samples were collected in Villa Vieja, on the left bank. The study area is located at 38º 14’ 55’’ lat. S; 67° 11’ 49’’ long. W at 232 msnm, downstream of Embalse Casa de Piedra dam. The results correspond to samples taken in February 2010, the period of maximum flow. The samples were collected with plankton net of 20 microns aperture observed in vivo and then fixed in formalin (4%). For studies of diatoms aliquots of the samples and subsequent treatment for the removal of organic matter and making diatom preparations. The physicochemical and environmental were recorded in situ by using portable sensors and subsequent laboratory techniques. Of all taxa identified to the present functional groups recorded were: 32.7% Bacillariophyceae, Chlorophyceae 44.3%, Cyanophyceae 11.5% and 11.5% other algae remaining partners, including Euglenophyceae.Instituto de Limnología "Raúl A. Ringuelet

Gaia Data Release 1. Principles of the photometric calibration of the G band

Context. Gaia is an ESA cornerstone mission launched on 19 December 2013 aiming to obtain the most complete and precise 3D map of our Galaxy by observing more than one billion sources. This paper is part of a series of documents explaining the data processing and its results for Gaia Data Release 1, focussing on the G band photometry. Aims. This paper describes the calibration model of the Gaia photometric passband for Gaia Data Release 1. Methods. The overall principle of splitting the process into internal and external calibrations is outlined. In the internal calibration, a self-consistent photometric system is generated. Then, the external calibration provides the link to the absolute photometric flux scales. Results. The Gaia photometric calibration pipeline explained here was applied to the first data release with good results. Details are given of the various calibration elements including the mathematical formulation of the models used and of the extraction and preparation of the required input parameters (e.g. colour terms). The external calibration in this first release provides the absolute zero point and photometric transformations from the Gaia G passband to other common photometric systems. Conclusions. This paper describes the photometric calibration implemented for the first Gaia data release and the instrumental effects taken into account. For this first release no aperture losses, radiation damage, and other second-order effects have not yet been implemented in the calibration

Gaia Early Data Release 3: Summary of the contents and survey properties

Context. We present the early installment of the third Gaia data release, Gaia EDR3, consisting of astrometry and photometry for 1.8 billion sources brighter than magnitude 21, complemented with the list of radial velocities from Gaia DR2. Aims. A summary of the contents of Gaia EDR3 is presented, accompanied by a discussion on the differences with respect to Gaia DR2 and an overview of the main limitations which are present in the survey. Recommendations are made on the responsible use of Gaia EDR3 results. Methods. The raw data collected with the Gaia instruments during the first 34 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium and turned into this early third data release, which represents a major advance with respect to Gaia DR2 in terms of astrometric and photometric precision, accuracy, and homogeneity. Results. Gaia EDR3 contains celestial positions and the apparent brightness in G for approximately 1.8 billion sources. For 1.5 billion of those sources, parallaxes, proper motions, and the (GBP − GRP) colour are also available. The passbands for G, GBP, and GRP are provided as part of the release. For ease of use, the 7 million radial velocities from Gaia DR2 are included in this release, after the removal of a small number of spurious values. New radial velocities will appear as part of Gaia DR3. Finally, Gaia EDR3 represents an updated materialisation of the celestial reference frame (CRF) in the optical, the Gaia-CRF3, which is based solely on extragalactic sources. The creation of the source list for Gaia EDR3 includes enhancements that make it more robust with respect to high proper motion stars, and the disturbing effects of spurious and partially resolved sources. The source list is largely the same as that for Gaia DR2, but it does feature new sources and there are some notable changes. The source list will not change for Gaia DR3. Conclusions. Gaia EDR3 represents a significant advance over Gaia DR2, with parallax precisions increased by 30 per cent, proper motion precisions increased by a factor of 2, and the systematic errors in the astrometry suppressed by 30-40% for the parallaxes and by a factor ~2.5 for the proper motions. The photometry also features increased precision, but above all much better homogeneity across colour, magnitude, and celestial position. A single passband for G, GBP, and GRP is valid over the entire magnitude and colour range, with no systematics above the 1% leve