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San Miguel de Tucumán, Argentina

Taboada M.L.A.,CONICET | Taboada M.L.A.,Institute Ficologia | Gultemirian M.L.,CONICET | Martinez De Marco S.N.,Institute Ficologia | And 2 more authors.
Boletin de la Sociedad Argentina de Botanica | Year: 2015

Tucumán is known for its richness in natural and water resources. Previous phycological studies focused mainly on the phytoplankton, but little was done in relation to the epilithic phycoflora. The aim of this research was to analyze the epilithic taxocenosis and physicochemical variables of Calimayo stream during an annual cycle, and to contribute to the taxonomic knowledge of the phycoflora in Northwestern Argentina. Physicochemical and biological samples collected in 2012-2013 were studied. The water was alkaline, bicarbonate-calcium, oligosaprobic in summer/13 and oligo-ß-mesosaprobic in the other seasons. Mineralization was average and the stream was well oxygenated. The Bacillariohyceae class presented 69 taxa followed by Divisions Cyanophyta (10), Chlorophyta (5) and Rhodophyta (1). The following species were always present: Amphipleura lindheimerii, Cocconeis placentula var. lineata, Cymbella affinis, Gomphonema olivaceum, G. parvulum, Luticola mutica, Navicula tripunctata, Nitzschia palea, Orthoseira roeseana, Planothidium frequentissimum, P. lanceolatum, Reimeria uniseriata, Rhoicosphenia abbreviata, Ulnaria ulna, Oedogonium sp., Lyngbya sp. 1, Myxosarcina spectabilis, Oscillatoria sp. 1 y 2. Of a total of 85 taxa, 70 are cited for the first time for epilithon and Myxosarcina spectabilis is a new record for Tucuman. Phycoflora composition was influenced by temperature, depth, precipitation and pH. Source

In this paper we analyzed the phytoplankton variation in the tributaries (Salí, Tapia, and Vipos rivers) and effluent (Salí River) from the C. Gelsi reservoir according to a seasonal gradient. The minimum algal abundance took place in summer with a biomass of 0.19-0.58 μg Cl-a L-1, while the maximum occurred in winter or in spring, with a biomass of 5.43-6.79 μg Cl-a L-1. In the tributaries pennate diatoms prevailed, Diatoma vulgare and Cymbella affinis were most abundant, while in the Salí river (Gelsi effluent) centric diatoms were dominant, particularly Aulacoseira granulata and Cyclotella meneghiniana. Chlorophyta were ranked second in the Salí River, Cyanobacteria codominated in the Vipos and Tapia rivers in March 1998, and Dinophyta could only be seen in the Salí River (Gelsi effluent). The specific diversity index ranged from 0.2 to 4.2 and the saprobic index characterized waters as "nonpolluted" or "slightly polluted" in winter, and as "moderately polluted" in summer. The NMDS arranged temporarily the samples according to the abundance of the algal species considered. The RDA showed that the two first axes separated the samples according to gradients of temperature, pH, conductivity, BOD5 and nitrate, and also abundance of Aulacoseira granulata, Cyclotella meneghiniana, Ulnaria ulna, Cymbella affinis and Leptolyngbya foveolarum. Source

Medina C.D.,Estacion de Fotobiologia Playa Union | Tracanna B.C.,Catedra Of Diversidad Vegetal Ii And Institute Of Limnologia Del Noroeste Argentino Ilinoa | Tracanna B.C.,Institute Ficologia | Hilal M.,Catedra Of Diversidad Vegetal Ii And Institute Of Limnologia Del Noroeste Argentino Ilinoa | And 2 more authors.
Lakes and Reservoirs: Research and Management | Year: 2010

A mesocosm experiment was conducted over a 4 week period to investigate the response of a phytoplankton community in a mountain freshwater reservoir to solar UV-B exclusion. The mesocosms were filled with water taken from the depth of 0.30 m in the reservoir, and exposed to near-ambient solar UV-B (+UV-B) and solar UV-B exclusion (-UV-B). The resulting chlorophyll-a (Chl-a), carotenoids, soluble sugars, algal composition and algal abundance were analysed. The study results indicated that carotenoids, carbohydrates and species distribution were affected under the -UV-B treatment. The carotenoid concentration was generally higher under the +UV-B treatment than under the -UV-B treatment. The sucrose and glucose concentrations were affected differently by the UV-B treatments, although both sugars strongly decreased under the +UV-B treatment by the end of the experiment. The sucrose and glucose concentrations exhibited similar distribution patterns to those of carotenoids for the +UV-B treatment, suggesting that these sugars could be directly involved in secondary metabolism. In contrast, the fructose content did not exhibit significant differences between UV-B treatments. The Chl-a concentration exhibited a progressive decrease during the experiment for both UV-B treatments. Although no significant impact of UV-B exclusion on the Chl-a concentration was observed in this study, a slightly higher concentration was observed for the -UV-B treatment. The total phytoplankton biovolume (BV) exhibited a pattern similar to that of the Chl-a concentration. Analysis of the phytoplankton composition revealed 52 species. However, because some species and classes were extremely difficult to identify, only 46 species from seven classes (Cyanophyceae, Chlorophyceae, Bacillariophyceae, Euglenophyceae, Charophyceae, Dinophyceae, Xanthophyceae) were unambiguously identified and considered for the UV-B treatments. Chlorophyceae, Bacillariophyceae and Cyanophyceae comprised about 78% of the identified species. Aulacoseira granulata and Cyclotella meneghiniana, followed by Ceratium hirundinella, were the most abundant species. Principal component analysis, using sampling periods and algal densities (PCA-1), indicated a heterogeneous phytoplankton assemblage, whereas PCA-2, with algal densities and biochemical variables (soluble carbohydrates, Chl-a and carotenoids), indicated that biochemical parameters could provide qualitative information about La Angostura phytoplankton community responses to quality of the sunlight. © 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Asia Pty Ltd. Source

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