About the Bacillariophyceae from natural wells in the Delta of the River Ebro

The Baltasar wells are water uprisings found on the Mediterranean Spanish coast, wich are closely connected with the River Ebro. These environments have variying leveles of chloride, high concentrations of calcium, and low levels of phosphates. Sixty two Bacillariophyceae taxa have been identified from three wells; the composition and ecological preferences of the diatom flora are discussedSobre las Bacilariofíceas de ojos de agua en el Delta del Ebro. Los Ullals de Baltasar son surgencias de agua localizadas en la costa mediterránea española y relacionadas con el río Ebro. Estos ambientes muestran variables concentraciones de cloruros, elevados concentraciones de calcio y bajos niveles de fosfatos. La flora diatomológica de tres ullals fue estudiada, identificándose 62 táxones; su composición y características ecológicas son discutidas

La proyección del infierno medieval en Hispanoamérica

El proceso de evangelización y adoctrinamiento de la población americana se valió, entre otros medios, de la imagen pictórica para implementar los dogmas y creencias de la Iglesia católica. La representación de las penas y tormentos infernales en vastos programas iconográficos en capillas de indios, desde el siglo XVI al XIX, testimonian una intencionalidad didáctica, persuasiva y coercitiva para lograr la conversión de la población indígena. El análisis iconográfico de algunos conjuntos pictóricos de Mesoamérica y el centro y sur andinos pretende demostrar la pervivencia de motivos y esquemas compositivos del arte infernal medieval

La Textualidad Léxico-Figurativa en los Beatos

La historia del Arte Medieval se ha sustentado convencionalmente en la afirmación de que la iconografía pictórico- escultórica ha abrevado exclusivamente en los textos bíblicos, lo que conlleva a reducir la imagen artística a un testimonio visual del texto, a una mera traslación de la palabra a su representación formal y material para la instrucción de los iletrados, transformándola en una iconografía dogmática. En consecuencia se ha soslayado el valor propio e intínseco de la imágenes, como asimismo la plurifuncionalidad que desempeñaron en la sociedad medieval. El texto del Commentarius in Apocalypsin de Beato tuvo enorme repercusión en el medio hispánico; en los siglos sucesivos se copió e ilustró profusamente; los treinta y dos códices del siglo IX al XIII, son prueba irrefutable del éxito de la obra. El presente estudio se abocará a la relación texto - imagen para constatar correlaciones, disimilitudes, presentificaciones autónomas, innovaciones plásticas que implicaron un desafío al sistema lógico imperante. Los iluminadores de Los Beatos, aún dependiendo de los versículos canónicos y de las exigencias del comitente, iconógráfico apocalíptico que testimonia una libertad creadora, una calidad artística y un manejo de las formas plástico- cromáticas que consagran a eso Códices como un monumento iconográfico absolutamente excepcional y único en el Arte de la Edad Media.The Art history of the Middle Age has been commonly based on the statement that the pictorial-sculptural iconography due its representation exclusively to sacred books. This approach reduce the artistic image to just a visual variant of the text, a mere translocation of the printed word to its formal and material representation with divulgation aims for the unlettered, converting this iconography in a dogmatic one. So, the rich and deep value of the images and their omnifunctionality in medieval society has been misjudged. The text Commentarius in Apocalypsin from Beato had huge publicity in the Hispanic world; with further and multiples copies and illustrations over the next centuries. The thirty-two codices from centuries IX to XIII are enough evidence of the great success of the text. This paper will focus on the relation between text and image to check correlations, dissimilarities, autonomous presentiveness, and plastic innovations that defied the logical system of the time. The illuminators of "Los Beatos", yet still depending on the canonical versicles and on the commiter demands, produced an iconographical-apocalyptic corpus that testimony a creative freedom, an artistic quality, and a masterfulness on the plasticchromatic ways, that enact those codices as an absolutely exceptional and one-of-a-kind iconographic monument from the Art of the Middle Age

Fluvial biofilm responses to joint changes in nutrients, temperature, turbidity and water velocity: an <i>ex situ</i> experiment

The aim of this study was to explore the responses of the epipelic biofilm of a Pampean stream with little impact from human activity to two environmental conditions, with joint modifications in nutrients, temperature, water velocity and turbidity. The experiment was conducted using artificial channels and lasted five weeks. The biological variables measured included chlorophyll-a content, bacterial biomass, ash-free dry weight, total carbohydrate concentration, total respiratory activity, and biofilm composition. Results show that the species´ composition of the biofilm was affected, although no other structural or metabolic variables measured were. These results highlight the importance of including structural parameters to measure rapid changes in water quality, even when analyzing the effects of co-occurring variables.Instituto de Limnología "Dr. Raúl A. Ringuelet"Consejo Nacional de Investigaciones Científicas y Técnica

Fluvial biofilm responses to joint changes in nutrients, temperature, turbidity and water velocity: an <i>ex situ</i> experiment

The aim of this study was to explore the responses of the epipelic biofilm of a Pampean stream with little impact from human activity to two environmental conditions, with joint modifications in nutrients, temperature, water velocity and turbidity. The experiment was conducted using artificial channels and lasted five weeks. The biological variables measured included chlorophyll-a content, bacterial biomass, ash-free dry weight, total carbohydrate concentration, total respiratory activity, and biofilm composition. Results show that the species´ composition of the biofilm was affected, although no other structural or metabolic variables measured were. These results highlight the importance of including structural parameters to measure rapid changes in water quality, even when analyzing the effects of co-occurring variables.Instituto de Limnología "Dr. Raúl A. Ringuelet"Consejo Nacional de Investigaciones Científicas y Técnica

Fluvial biofilm responses to joint changes in nutrients, temperature, turbidity and water velocity: an <i>ex situ</i> experiment

The aim of this study was to explore the responses of the epipelic biofilm of a Pampean stream with little impact from human activity to two environmental conditions, with joint modifications in nutrients, temperature, water velocity and turbidity. The experiment was conducted using artificial channels and lasted five weeks. The biological variables measured included chlorophyll-a content, bacterial biomass, ash-free dry weight, total carbohydrate concentration, total respiratory activity, and biofilm composition. Results show that the species´ composition of the biofilm was affected, although no other structural or metabolic variables measured were. These results highlight the importance of including structural parameters to measure rapid changes in water quality, even when analyzing the effects of co-occurring variables.Instituto de Limnología "Dr. Raúl A. Ringuelet"Consejo Nacional de Investigaciones Científicas y Técnica

Effects of pulse and press additions of salt on biofilms of nutrient-rich streams

Chronic and pulse increments of salinity can cause different consequences on the aquatic communities, and its effects are related to factors such as the magnitude, frequency and ionic composition, as well as on the baseline salt concentrations in the water. The aim of this study was to explore the responses of the biofilms from a nutrient-rich stream to both pulse and chronic additions of salt, along with their recovery after the stressor had been removed. For this purpose, a microcosm study was conducted exposing biofilms to water enriched with sodiumchloride in two treatments (press and pulse), and comparing the changes in the biofilm with control microcosms without salt additions. The experiment lasted 72 h, and the variables measured included bacterial density, chlorophyll-a concentration, community composition, total carbohydrate content, oxygen consumption and the percentage of nuclear alterations in diatoms. Both treatments resulted in a decrease in the bacterial density of the biofilm and in oxygen consumption; the chronic treatment in particular also caused an increased percentage of nuclear abnormalities in the diatom assemblage. The biofilm recovered to control levels after the treatments had been discontinued for 72 h. We concluded that the biofilms can be altered significantly under both chronic and pulse additions of salt even after a short-term exposure, and that the community can recover if the stressor is withdrawn.Instituto de Limnología "Dr. Raúl A. Ringuelet