El objetivo de este trabajo es analizar las variaciones espacio-temporales del fitoplancton de la zona limnética del embalse Escaba y la desembocadura de sus tributarios: ríos Chavarría, Las Moras, El Chorro y Singuil, respecto a variables fisicoquímicas para caracterizar la calidad del agua durante 2010-2012. Se determinaron 135 taxones: Bacillariophyceae (77), Chlorophyta (40), Cyanophyta (12), Euglenophyta (5) y Dinophyta (1). La densidad algal varió de 84 a 6924 ind/ml y Ceratium hirundinella fue dominante excepto en primavera de 2011. La clorofila a tuvo un rango variable a nivel temporal y espacial fluctuando entre 6 y 2511 ?g/l, encontrándose mayores registros en los5afluentes. Los elevados valores de biomasa y la caracterización polisapróbica de sus aguas determinaron un estado ecológico deficiente o malo. La diversidad específica osciló entre 0-2,76. El modelo lineal generalizado detectó cambios en las abundancias de C. hirundinella entre las dos temporadas, sitios y meses acompañados por diferencias en algunas variables fisicoquímicas (amonio, OD y DBO5) Sólo se observó durante noviembre de 2011 una relación inversa entre la densidad del dinoflagelado con el amonio. Este trabajo aportó al conocimiento de la biodiversidad algal del embalse Escaba y amplió la distribución de C. hirundinella en la provincia de Tucumán.
Nuevos registros de Bacillariophyceae en ecosistemas lóticos del Noroeste de Argentina IIä Resumen -Las diatomeas (Bacillariophyceae) constituyen un importante componente de las taxocenosis acuáticas, pueden vivir en una amplia variedad de hábitats, son organismos muy comunes y abundantes en los sistemas lóticos del Noroeste Argentino (NOA). El objetivo propuesto en este trabajo fue dar a conocer 20 nuevos registros de estas microalgas: 3 nuevas citas para el país, 5 para la región del noroeste y 12 nuevos registros para Tucumán. Se realizaron muestreos estacionales en los arroyos: Calimayo y Mista (ambos pertenecientes a la cuenca del río Sali) desde 2012 a 2014, se recolectaron datos biológicos (epiliton y fitoplancton) e "in situ" se midieron variables abióticas según metodologías convencionales. Se efectuaron descripciones de las especies, se obtuvieron características morfométricas, se analizó la distribución geográfica y rasgos autoecológicos de los taxones registrados por primera vez para el NOA y el país. Se incorporan microfotografías (MO) de las especies citadas. Esta contribución permitió incrementar el conocimiento, la distribución y la autoecología de los taxones de diatomeas considerados.Palabras clave: Diatomeas; Noroeste Argentino; Sistemas hídricos.ä Abstract -Diatoms (Bacillariophyceae) are an important component of aquatic taxocenosis that can live in a wide variety of habitats, which are very common and abundant organisms in NOA's lotic ecosystems. The objective of this work was to present 20 new records of these microalgae: 3 new citations for the country, 5 for the Northwest region and 12 new records for Tucumán. Seasonal samplings were carried out from 2012 to 2014 in Calimayo and Mista streams (both belonging to the Sali river basin). Biological data (epilithon and phytoplankton) were collected "in situ". Abiotic factors were measured according to conventional methodologies. Descriptions of the species were made and morphometric characteristics were obtained, the geographic distribution and autoecological traits of the taxa registered for the first time for the NOA and the country were analyzed. Microphotographs (MO) of the cited species were incorporated. This contribution allowed to increase the knowledge, distribution and autoecology of the diatom species analyzed.
Tucumán se destaca por sus riquezas en recursos naturales e hídricos. Los estudios ficológicos se basaron principalmente en el fitoplancton, siendo escaso el análisis de la ficoflora epilítica. Los objetivos fueron analizar la taxocenosis epilítica y variables fisicoquímicas del arroyo durante un ciclo anual y contribuir al conocimiento de la ficoflora del NOA. Se estudiaron muestras fisicoquímicas y biológicas recolectadas durante 2012-2013. El agua tuvo un pH alcalino, se caracterizó como bicarbonatada-cálcica, oligosapróbica (verano/13) y oligo-?-mesosapróbica en las otras estaciones. La mineralización fue media y el arroyo estuvo bien oxigenado. La Clase Bacillariohyceae presentó 69 taxones seguida de las Divisiones Cyanophyta (10), Chlorophyta (5) y Rhodophyta (1). Las especies siempre presentes fueron: Amphipleura lindheimerii, Cocconeis placentula var. lineata, Cymbella affinis, Gomphonema olivaceum, G. parvulum, Luticola mutica, Navicula tripunctata, Nitzschia palea, Orthoseira roeseana, Planothidium lanceolatum, P. frequentissimum, Reimeria uniseriata, Rhoicosphenia abbreviata, Ulnaria ulna, Oedogonium sp., Lyngbya sp.1, Myxosarcina spectabilis, Oscillatoria sp. 1 y 2. Las mayores densidades se presentaron en época invernal. De un total de 85 taxones, 70 se citan por primera vez para el epiliton y Myxosarcina spectabilis es un nuevo registro para Tucumán. La composición de la ficoflora estuvo influenciada por: temperatura, profundidad, precipitaciones y pH.
Aim:The Escaba dam is located in the south of the Tucumán province, Argentina, at 650 m above sea level. It has an extension of 541 ha. and a depth of 65 m and its tributaries are the Chavarría, Las Moras, El Chorro and Singuil rivers. The climate is mild with dry winters and rainy summers. The objective of this study was to characterize physicochemical parameters in the limnetic zone of the dam and the mouths of the tributaries to determine the water quality. Methods: Seasonal sampling was carried out between August 2010 and May 2012. Temperature, transparency, pH and electrical conductivity were field measured, whereas dissolved oxygen, biochemical oxygen demand (BOD 5 ), major ion constituents and nitrogen and phosphate compounds were analyzed at the laboratory. Results: The water was classified as sodium-calciumbicarbonate with neutral to alkaline pH, and thermal stratification during spring and summer. The water assayed was well oxygenated except for the bottom of the limnetic zone during the summer months. Lowest transparency was measured in the El Chorro Keywords: abiotic factors, water quality, Escaba dam, Tucumán, Argentina.Resumo: Objetivo: A represa Escaba está localizada ao sul da província de Tucumán, a 650 metros de altitude, sua extensão é de 541 ha, tem 65 m de profundidade e seus afluentes são os Rios Chavarria, Las Moras, El Chorro e Singuil. O clima é temperado, com invernos secos e verões chuvosos. O objetivo do estudo foi caracterizar as propriedades físicas e químicas das águas limnéticas da represa e da foz dos seus afluentes, para interpretar a qualidade de suas águas. Métodos: Realizaram-se amostragens estacionais de agosto de 2010 até maio de 2012. As variáveis medidas in situ foram: temperatura, transparência, pH, condutividade elétrica, e no laboratório foram analisados: oxigênio dissolvido, demanda bioquímica de oxigênio (DBO 5 ), íons principais, compostos nitrogenados e fosfatados. Resultados: O tipo de água é bicarbonatada-cálcica-sódica, de neutra a alcalina e detectou-se estratificação térmica na primavera e verão. Com exceção da zona limnética: fundo, nos meses mais quentes, as águas estiveram bem oxigenadas. Em novembro de 2011 no rio El Chorro, obteve-se o valor mais baixo de transparência: 0,12
Physical, chemical and biological variability in the Dr. C. Gelsi reservoir (NW Argentine): A temporal and spatial approachWith the purpose of understanding the phytoplankton dynamics in two vertical profiles of the Dr. C. Gelsi reservoir (Tucumán, Argentina, monthly samplings were conducted from October 1997 to March 1999 in the limnetic zone and at the intersection of the Salí and Tapia tributary. The reservoir was characterized as warm monomictic, with bicarbonate, chloride, sodium, calcium and/or magnesium waters. In both sites total nitrogen concentration was higher than 1 mg/l, whereas that of orthophosphate reached 0.2 mg/l. Out of the eleven organochlorine pesticides analyzed, the presence mainly of lindane and methoxychlor, with higher concentrations in the warm months was confirmed. Bacterial load values were compatible with water quality standards, and variations in the number of actinomycetes colonies in the sediments were correlated, among other parameters, with dissolved oxygen. In the two zones studied a total of 57 phytoplankton taxa, 49 % green algae, 37 % diatoms, 9 % Cyanobacteria and 5 % dinoflagelates, were identified. Central diatoms (Aulacoseira granulata and Cyclotella meneghiniana) prevailed in the phytoplankton and, in a lesser degree, the other groups, low values of specific diversity being obtained. A principal components analysis based on the absolute abundance of species and on some physico-chemical parameters ordinated the samples of the various levels, this abundance being more evident in the limnetic zone. There was also a tendency to the separation of stratifications from the two consecutive years and homogeneity in the samples from the mixing period was noticed. On the basis of the saprobic index, water quality was from β − α-mesosaprobic to α-mesosaprobic.
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