Artículos, informes y presentaciones en Congresos
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Examinando Artículos, informes y presentaciones en Congresos por Autor "Bauer, Delia Elena"
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Acceso Abierto Diversidad fitoplanctónica en la franja costera sur del Río de la Plata(2000) Gómez, Nora; Bauer, Delia ElenaDiversity of phytoplankton from the Southern Coastal Fringe of the Rio de la Plata between 58°32' and 57°41' W, up to 10 km from the coast line was analized. The present study show the results of the sampling carried outside peces between 1993-1997. The species identified were illustrated and a brief ecological and meristic description was done for each taxon. A total of 211 samples were analysed and 172 taxa were found. The phytoplankton structure showed the predominance of few species and the highest diversity was located near the coast. The green algae and the diatoms were frequents and sometime the most abundant groups. Suspend solids carried by the river, stational and climatic changes and antropic disturbance are the most important factors in phytoplankton development. A few brachish-water or marine species have been found in the zone studied. According to ecological features the phytoplankton analysed was eutrophic, oligohalophilous and mesosaprobic. - Artículo
Embargado Influence of El Niño Southern Oscillation phenomenon on coastal phytoplankton in a mixohaline ecosystem on the southeastern of South America: Río de la Plata estuary(2015) Sathicq, María Belén; Bauer, Delia Elena; Gómez, NoraThe aim of this study was to analyze the density, diversity, biomass and assemblage composition of the phytoplankton in relation to environmental conditions (physical, chemical, hydrological and meteorological variables), measured under the different scenarios caused by the ENSO phenomenon in the period between 2005 and 2012, in six sampling sites in the tidal freshwater zone of the Río de la Plata estuary, covering almost 100 km of coastline. The results revealed changes in the structure of the phytoplankton, such as a significant reduction of diversity, and decreases in biomass and phytoplankton density, particularly during El Niño phases. Cyanobacteria were more abundant in the neutral periods, Chlorophyceae dominated La Niña phase while Bacyllariophyceae dominated El Niño. However, no complete replacement of species between cycles was observed. The results obtained were highly variable due to the inherent natural variability of the Río de la Plata, emphasized by the anthropogenic impact in this area. - Artículo
Embargado Phytoplankton of a small lowland stream related to water quality and hydraulic discontinuities(2002) Bauer, Delia Elena; Conde, María E.; Gómez, NoraThe structure and dynamics of the phytoplankton related to water quality and hydraulic characteristics were studied in a 12 km reach of the Rodríguez Stream, a tributary of the Río de la Plata, in Argentina. This stream includes a small artificial pond. Samples were taken seasonally along a year at three sites at the stream and once at the pond. Water quality according to physical and chemical parameters was better at site 1 than at downstream sites. Changes in phytoplankton assemblages descriptors were observed with increasing nutrients and water residence time. The spatial water quality changes are coincident with the hydraulic discontinuity. This situation suggests a synergic effect among the phytoplanktonic descriptors that were analyzed. There was a high percentage of species belonging to euglenoids followed by green algae and diatoms. Loricated euglenoids were dominant at site 1, clorococcalean greens dominated at the pond and decreased progressively downstream, at sites 2 and 3. Gomphonema parvulum, Nitzchia palea and N. umbonata were abundant in the latter sites, where current velocity increased. Our results also show the integrating character of the phytoplankton in this small stream where it can reach considerable development due to the low gradient ($latex <10^{-3} $), and specially to the presence of the pond. - Artículo
Embargado Use of phytoplankton assemblages to assess the quality of coastal waters of a transitional ecosystem: Río de la Plata estuary(2016) Sathicq, María Belén; Gómez, Nora; Bauer, Delia Elena; Donadelli, Jorge L.Among the estuarine ecosystems under anthropogenic stress, the Río de la Plata can represent a case study to help identify phytoplanktonic species diagnosing and warning about water quality changes. The freshwater tidal zone on the coast of Argentina is used for several purposes, including recreational and navigational activities and the provision of drinking water. We analyzed the relationship between the abundance of the phytoplanktonic species, changes in water quality (linked to enrichment with nutrients and organic matter) and the land use on the coast of Argentina. A canonical correlation analysis (CCA) allowed us to identify two environmental gradients, one related to anthropogenic activities, where the most influential factors were BOD5, DIN, PO4 3- and DO, and a second gradient related to turbidity and conductivity. The relative abundances of 24 species were significantly correlated with the deterioration of the water quality. This set of tolerant species is mostly composed of taxa considered C-strategists, and the most represented group was the Chlorococcalean algae. The percentage of this group can provide an early warning indicator of the impairment of the water quality; its abundance exceeded 30% at those sites with a bad water quality (reaching 19000 cell mL-1), and were less than 15% (300 cell mL-1) in sites with a good water quality. The use of a reduced group of species constitutes a potential tool for monitoring, complementing another common indicators such as chlorophyll a or the total density of phytoplankton. Considering that most of these tolerant species are widely distributed it is possible to employ them as a biomonitor in other freshwater zones of temperate estuaries.