ILPLA
URI permanente para esta comunidad
El Instituto de LimnologĆa "Dr. RaĆŗl A. Ringuelet" tiene como objetivo central el estudio ecolĆ³gico de las aguas continentales de la Argentina a travĆ©s de un enfoque integrado de los procesos fĆsicos, quĆmicos, geolĆ³gicos y biolĆ³gicos originados en los ambientes acuĆ”ticos.
Los proyectos de investigaciĆ³n estĆ”n dirigidos a:
- EvaluaciĆ³n de la productividad biolĆ³gica
- CaracterizaciĆ³n quĆmica y fĆsica de las aguas
- Interacciones entre ecosistemas acuƔticos y terrestres
- ComposiciĆ³n y dinĆ”mica de las comunidades biolĆ³gicas
- AdaptaciĆ³n de los organismos acuĆ”ticos
La transferencia de resultados estƔ orientada a proveer las bases para el mantenimiento de la calidad, la biodiversidad y de un aprovechamiento sustentable de los ambientes acuƔticos continentales. Gran parte de sus actividades incluye identificar, diagnosticar y prescribir soluciones efectivas a problemas ambientales.
Los proyectos de investigaciĆ³n estĆ”n dirigidos a:
- EvaluaciĆ³n de la productividad biolĆ³gica
- CaracterizaciĆ³n quĆmica y fĆsica de las aguas
- Interacciones entre ecosistemas acuƔticos y terrestres
- ComposiciĆ³n y dinĆ”mica de las comunidades biolĆ³gicas
- AdaptaciĆ³n de los organismos acuĆ”ticos
La transferencia de resultados estƔ orientada a proveer las bases para el mantenimiento de la calidad, la biodiversidad y de un aprovechamiento sustentable de los ambientes acuƔticos continentales. Gran parte de sus actividades incluye identificar, diagnosticar y prescribir soluciones efectivas a problemas ambientales.
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- Informe de personal de apoyo
Acceso Abierto Informe de personal de apoyo: DomĆ”nico, Alejandro Arturo (1999-2000)(2000) DomĆ”nico, Alejandro ArturoProyectos de investigaciĆ³n en los cuales colabora: a) ProspecciĆ³n del potencial pesquero del Partido de ChascomĆŗs para el ordenamiento territorial de sus lagunas. - ArtĆculo
Acceso Abierto Diversidad fitoplanctĆ³nica en la franja costera sur del RĆo de la Plata(2000) GĆ³mez, Nora; Bauer, Delia ElenaDiversity of phytoplankton from the Southern Coastal Fringe of the Rio de la Plata between 58Ā°32' and 57Ā°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. - ArtĆculo
Acceso Abierto Diversidad de invertebrados bentĆ³nicos del RĆo de la Plata(2000) CĆ©sar, InĆ©s Irma; OcĆ³n, Carolina S.; Paggi, AnalĆa Constancia; Rodrigues CapĆtulo, Alberto; Spaccesi, Fernando G.; Tangorra, M.; Tassara, MĆ³nica P.The Rio de la Plata river present along the south coastal fringe different invertebrate assemblages related with substrate type, size sediment grains and organic matter content into the bedsediments. Other important factors influencing the distribution of benthos community in this river are the salinity and suspended solids of the water and the proximity to the riverside which increases the diversity of the habitats. The purpose of this study is to describe the taxonomic composition and ecological characteristics of the meso and macrobenthos associated with the river bed from Delta del ParanĆ” to Magdalena, in Buenos Aires province. The listed taxa are the result of the revised literature and original data obtained from periodical samplings since 1993 till 1998. The principal components of the zoobenthos in the studied area were the allochthonous molluscs Corbicula fluminea on sandy and muddy bottoms and Limnoperna fortunei on hard substrates of the riverside. The nematods and oligochaetes dominated sediments with high allochthonous organic matter content imported from urban effluents. Palaemonetes argentinus, Macrobrachium borelli, Claudicuma platensis, Sinelobus stanfordi, Basphaeroma rhonbofrontale and Trichodactylus panoplus were the more common crustaceans in non polluted areas. - ArtĆculo
Acceso Abierto Estudio ictiolĆ³gico del puerto de la ciudad de Buenos Aires(2000) Remes Lenicov, Mauricio; Colautti, DarĆo C.The port of Buenos Aires is located in the Rio de la Plata river on the riverside of the homonymous city. The fish community that inhabits the port waterās was studied in order to know the specific composition, relative abundance, spatial distribution and its relationships with the port activities. Ten sampling places were considered, seven inside the port and three in the access channels. The sampling was realised on August and September of 1998, using active and passive fishing gears. Diversity indices, Margalef' (Rl) and Shannon and Weaver (HO, were calculated. A cluster analysis was carried out with relative abundance of each taxa. In access channels, four species were captured and its relative abundance and diversity were similar for each stations. Contrarily inside the port twenty-seven species was registered, the relative abundance and specific composition were more fluctuate than out side. The heterogeneity observed in the distribution of the fish community would be linked to the design of the port and the activities that are developed in each place. - Informe de personal de apoyo
Acceso Abierto Informe de personal de apoyo: DomĆ”nico, Alejandro Arturo (2001-2002)(2002) DomĆ”nico, Alejandro ArturoProyectos de investigaciĆ³n en los cuales colabora: a) ProspecciĆ³n del potencial pesquero del Partido de ChascomĆŗs para el ordenamiento territorial de sus lagunas. - ArtĆculo
Embargado Phytoplankton of a small lowland stream related to water quality and hydraulic discontinuities(2002) Bauer, Delia Elena; Conde, MarĆa E.; GĆ³mez, NoraThe structure and dynamics of the phytoplankton related to water quality and hydraulic characteristics were studied in a 12 km reach of the RodrĆguez Stream, a tributary of the RĆo 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. - ArtĆculo
Acceso Abierto Estudios zoobentĆ³nicos recientes en el RĆo de la Plata(2004) Rodrigues CapĆtulo, Alberto; OcĆ³n, Carolina S.; Tangorra, M.; Paggi, AnalĆa Constancia; Cortelezzi, Agustina; Spaccesi, Fernando G.The present study shows the most important results in the sampling carried out in the RĆo de la Plata river from the year 1993. The main components of the zoobenthos in the studied area were the oligochaetes and nematods, particularly in sectors with high organic matter content and low dissolved oxygen. Tubificidae was very frequent, mainly Limnodrilus claparedeianus. A prevalence of Corbicula fluminea among the mollusks was observed in the coastal area in association with Limnoperma fortunei. This assemblage supports the presence of macroinvertebrates as Hirudinea, Temnocephala, Lumbriculidae, etc. Chironomidae showed an almost constant presence in the internal and intermediate areas of the river. The most frequent microcrustaceous were Copepoda, Cladocera, Ostracoda and their larval forms. In the offshore of the river the mollusks, annelids, crustaceans and nematods were present in the great majority of the sampling sites. Polychaeta were present in 90% of the sampling places being Nephtidae the most abundant genus. Corbicula fluminea dominated in the interior sector of the river and it was replaced by Erodona mactroides and Mactra isabelleana in the external area. Rapana venosa was also observed in this area. Different benthic assemblages were determined and their faunistic composition varied in function of the substrate, silt, size, coast, proximity, organic matter content and food resources. - Comunicacion
Acceso Abierto First records of invasive snail Melanoides tuberculatus (Gastropoda: Prosobranchia: Thiaridae) to the IguazĆŗ River basin, Argentina ā Brazil(2007) Gutierrez Gregoric, Diego E.; NuƱez, MarĆa VerĆ³nica; Ferrando, Noelia Soledad; Rumi, AlejandraIn this work is reported the first record of Melanoides tuberculatus in the IguazĆŗ River basin (Argentina-Brazil). This species is native to southern Asia and was anthropogenically introduced to America in the 1960s decade. Sixteen specimens (one adult and 15 juvenile) of M. tuberculatus were recorded at only one site, the rapids of IguazĆŗ River at Isla San MartĆn, IguazĆŗ National Park, Argentina, in June 2005. This finding of M. tuberculatus specimens suggests the presence of a stable population that would represent a threat to the native mollusk fauna, given that this species promotes replacement and impoverishment of mollusk diversity. - ArtĆculo
Acceso Abierto VariaciĆ³n estacional del fitoplancton en la cuenca inferior del RĆo Salado (provincia de Buenos Aires)(2008) Bazzuri, MarĆa Elisa; Gabellone, NĆ©stor AdriĆ”n; Solari, LĆa C.The main aim of this survey was to analyze seasonal variations in phytoplankton composition, relating its behaviour to temperature and conductivity, at El Destino (ED) sampling site in the Salado river lower-basin. A total of 28 phytoplankton samples were taken twice a week from 9/3 to 20/7/2004 and were analysed according to Utermƶhl method. In total, 145 algae taxa were identified, although rare species were discarded in order to avoid statistical misinterpretation. Correlation coefficients and autocorrelation analyses (Q-Ljung-Box statistic) were performed in order to establish seasonal patterns of species abundance. Significant autocorrelations (p <0.05) were observed between phytoplankton species and temperature-conductivity patterns, thus illustrating their seasonal behaviour. Moreover, taxa were grouped according to their occurrence during different water temperature periods: (1) a āsummerā group, included 41 species that were well represented during warm-waters (>22ĀŗC) like Planctonema lauterbornii, Chondrocystis dermochroa, Geminella interrupta, Chrooccocus spp., Merismopedia spp., among others; (2) a āwinterā group, which included 10 species whose highest densities were reached during the cold-waters period (<12ĀŗC) for e.g. Binuclearia sp, Nitzschia fruticosa, Schroederia indica, Microcystis firma; (3) a ātransitionalā group, of only 4 species with abundance peaks during āintermediateā conditions (15.5ĀŗC average) with Closteriopsis acicularis and Nodularia spumigena being the most remarkable; and (4) an āindifferentā group, with 29 species of random behaviour whose autocorrelations remain within confidence limits, like Thorakochloris nygaardii, Pseudoanabaena limnetica, Monoraphidium giffithii, Scenedesmus linearis, etc. An evident seasonal succession was detected, having species substitution from summer warm-stagnant adapted species to cold-waters favoured ones, hence indicating different successional stages. - Documento de conferencia
Acceso Abierto Influencia ecolĆ³gica de los canales de drenaje de la pampa arenosa en la cuenca superior del rĆo Salado (Bs. As., Argentina)(2010) Bazzuri, MarĆa Elisa; Gabellone, NĆ©stor AdriĆ”n; Solari, LĆa C.La construcciĆ³n de canales en la cuenca superior de rĆo Salado ha provocado cambios en su red de drenaje, vinculando zonas arreicas de alto contenido salino provenientes de la Pampa Arenosa. Con el fin de estudiar sus consecuencias en la dinĆ”mica ecolĆ³gica del rĆo se analizaron parĆ”metros fĆsico-quĆmicos y muestras de plancton para 5 sitios de muestreo en Mayo 2007. Los canales aportan al sistema aguas salinas, ricas en nutrientes, de bajo contenido en oxĆgeno disuelto (OD) y abundante plancton (cianobacterias coloniales, rotĆferos y ciliados). En el rĆo se observaron aguas con menor tenor salino, mayor OD y diferente composiciĆ³n planctĆ³nica (clorofitas clorococales y escaso zooplancton). En condiciones de aguas altas no se observaron modificaciones en las caracterĆsticas del rĆo aguas abajo del trasvase. Estos resultados muestran que el sistema de humedales asociados amortiguan los aportes alĆ³ctonos de las canalizaciones y su influencia no deberĆa desestimarse en futuros proyectos hidrĆ”ulicos. - Informe de personal de apoyo
Acceso Abierto Informe de personal de apoyo: Sendra, Eduardo Daniel (2011-2012)(2012) Sendra, Eduardo DanielProyectos de investigaciĆ³n en los cuales colabora: a) Tratamiento estadĆstico computarizado de los datos y registros pesqueros. b) DiagramaciĆ³n de las tareas de campo con relaciĆ³n a los muestreos realizados para cumplimentar el muestreo ictiolĆ³gico y relevamiento de parĆ”metros limnolĆ³gicos. c) Procesamiento merĆstico de las muestras de peces d) Mantenimiento de equipos de muestreo y compra de materiales. e) TraducciĆ³n al idioma inglĆ©s y al castellano de textos y publicaciones cientĆficas. f) RecopilaciĆ³n computarizada y revisiĆ³n crĆtica de material bibliogrĆ”fico g) Asesoramiento a becarios y a tĆ©cnicos con relaciĆ³n a los temas antes comentados y, ademĆ”s, a particulares sobre el manejo y aprovechamiento del recurso pesquero -continental. h) Estudio de la alimentaciĆ³n y relevamiento ictiolĆ³gico del AĀŗ La Choza (Cuenca del Rio Reconquista, Prov. Bs.As.). i)ConfecciĆ³n de prueba de galera:āElsevier Editorial System(tm) for Ecological Modelling Manuscript Draftā (ver versiĆ³n electrĆ³nica adjunta). j)Apoyo de laboratorio y gabinete con respecto al proyecto PID-CONICET Relaciones trĆ³ficas de macroinvertebrados en sistemas lĆ³ticos pampeanos: utilizaciĆ³n de grupos funcionales alimentarios como herramienta para detectar cambios en el ambiente. 2011-13. - Director: Alberto Rodrigues CapĆtulo. - Informe de personal de apoyo
Acceso Abierto Informe de personal de apoyo: Bauer, Delia Elena (2011-2012)(2012) Bauer, Delia ElenaProyectos de investigaciĆ³n en los cuales colabora: a) Medidas de integridad biĆ³tica para la costa del RĆo de la Plata (Argentina). Directora Nora GĆ³mez. ANPCyT, PICT 32077. 2007-2011. b) Nuevos descriptores para la evaluaciĆ³n de la calidad del agua en sistemas lĆ³ticos pampeanos. Director Alberto Rodrigues CapĆtulo. ANPCyT, PICT 33939. 2007-2011. c) Estudio de la integridad biĆ³tica de las comunidades planctĆ³nicas y bentĆ³nicas en sistemas lĆ³ticos de la llanura pampeana y su relaciĆ³n con los usos del suelo: su aplicaciĆ³n en la evaluaciĆ³n y monitoreo. Director: Dr. Alberto Rodrigues CapĆtulo. Acreditado por la UNLP, 01/01/2010 al 31/12/2014. - Informe de personal de apoyo
Acceso Abierto Informe de personal de apoyo: Bauer, Delia Elena (2012-2013)(2013) Bauer, Delia ElenaProyectos de investigaciĆ³n en los cuales colabora: a) Estudio de la integridad biĆ³tica de las comunidades planctĆ³nicas y bentĆ³nicas en sistemas lĆ³ticos de la llanura pampeana y su relaciĆ³n con los usos del suelo: su aplicaciĆ³n en la evaluaciĆ³n y monitoreo. Director: Dr. Alberto Rodrigues CapĆtulo. Acreditado por la UNLP, 01/01/2010 al 31/12/2013. b) Biomonitores microbiolĆ³gicos como indicadores de estrĆ©s ambiental en sistemas lĆ³ticos pampeanos. Director: Dra. Nora GĆ³mez, Codirector: Dra. Magdalena Licursi. CONICET PIP 2011-2013 GI 11220100100296 - Informe de personal de apoyo
Acceso Abierto Informe de personal de apoyo: Di Giorgi, Hugo Daniel (2012-2013)(2013) Di Giorgi, Hugo Daniel3. Proyectos de investigaciĆ³n en los cuales colabora: a) Convenio de asistencia tĆ©cnica āAsistencia TĆ©cnica Efluentes Mayor ConversiĆ³nā entre la Facultad de IngenierĆa (FI) UNLP e YPF SA. b) āAcceso al Agua de los Agricultores Familiares de la RegiĆ³n Pampeanaā, proyecto del Instituto de InvestigaciĆ³n y Desarrollo TecnolĆ³gico para la PequeƱa Agricultura Familiar (IPAF) RegiĆ³n Pampeana, dentro del Proyecto EspecĆfico Nacional AERN 291682 āManejo Integral del Agua para la Agricultura Familiar y Productores de Secanoā del INTA. c) Fortalecimiento de la producciĆ³n lĆ”ctea a baja escala. Proyecto de ExtensiĆ³n UNLP acreditado sin subsidio en 2012, dirigido por el Ing. Agr. RamĆ³n Cieza, con participaciĆ³n de las Facultades de Ciencias Agrarias y Forestales (UE), Veterinarias y Naturales y Museo UNLP. - ArtĆculo
Embargado Temporal distribution of cyanobacteria in the coast of a shallow temperate estuary (RĆo de la Plata): some implications for its monitoring(2014) Sathicq, MarĆa BelĆ©n; GĆ³mez, Nora; Andrinolo, DarĆo; SedĆ”n, Daniela; Donadelli, Jorge L.The aim of this study was to analyze the temporal distribution of phytoplanktonic cyanobacteria in a site located in the freshwater tidal zone near the extraction point for the drinking water supply. Samples were taken considering three timescales as follows: hours, days, and weeks, during the period of highest development of cyanobacteria. The phytoplankton density, microcystin concentration (LR, RR, YR), and chlorophyll-a were related to meteorological variables (wind and temperature), tidal high, and physicalchemical variables (nutrients, pH, conductivity, light penetration). The results obtained in this study showed that the variables that primarily modulate the temporal distribution of cyanobacteria were temperature, pH, light penetration, conductivity, and nutrients (particularly NO3 ā and NH4 + ), while the winds and tide had a secondary effect, only evidenced at an hourly scale. Therefore, this timescale would be the most suitable for monitoring cyanobacterial populations, when the amount of cyanobacterial cells exceeds the alert I level proposed by the World Health Organization. This recommendation is particularly important for the water intake zones in RĆo de la Plata, which are vulnerable to the damage generated by cyanobacteria on the water quality. - Contribucion a revista
Acceso Abierto EvaluaciĆ³n de calidad de agua mediante el estudio de macroinvertebrados(2015) Mauad, MelinaLos crecientes problemas de degradaciĆ³n ambiental que mundialmente afectan a los ecosistemas acuĆ”ticos han llevado a la necesidad de monitorear la calidad del agua de los mismos y una de las maneras mĆ”s prĆ”cticas y a la vez mĆ”s eficientes, es el monitoreo biolĆ³gico utilizando los macroinvertebrados bentĆ³nicos. El objetivo general de este trabajo fue la aplicaciĆ³n de distintos Ćndices biĆ³ticos en tres sistemas de rĆos y tributarios dentro del Parque Nacional Nahuel Huapi (PNNH) que presentaron diferentes disturbios antrĆ³picos: sistema Challhuaco-Ćireco, sistema Catedral-GutiĆ©rrez y sistema Manso Inferior-Villegas. Los resultados obtenidos a partir de los anĆ”lisis fĆsico-quĆmicos del agua, del anĆ”lisis taxonĆ³mico de las comunidades de macroinvertebrados bentĆ³nicos, de la aplicaciĆ³n y la comparaciĆ³n de los diferentes Ćndices biĆ³ticos y del anĆ”lisis estadĆstico aplicado, permitieron realizar una evaluaciĆ³n de la calidad de las aguas en dichos sistemas acuĆ”ticos y una comparaciĆ³n de los diversos Ćndices considerados, pudiendo indicar cuĆ”l es el mĆ”s apropiado para aplicar en la zona de estudio y para realizar futuros biomonitoreos en otros sistemas lĆ³ticos de Patagonia Norte. - ArtĆculo
Acceso Abierto New approaches for growth improvement in pejerrey Odontesthes bonariensis (Valenciennes, 1835) culture (Atherinomorpha: Atherinopsidae)(2015) Solimano, Patricio J.; GarcĆa de Souza, Javier Ricardo; Maiztegui, TomĆ”s; BaigĆŗn, Claudio R. M.; Colautti, DarĆo C.The pejerrey is the most important recreational species in shallow temperate lakes and reservoirs of Argentina and the attempts to develop its culture have started a century ago. A common constraint of pejerrey aquaculture is its poor growth under traditional intensive rearing techniques. The aim of this study was to evaluate the possibility to achieve and maintain high growth rates of pejerrey throughout the rearing process by semi-intensive culture method . Four floating cages were installed in La Salada de Monasterio Lake and each one was stocked with 300 juveniles (10.22 Ā±0.38cm; 6.52 Ā±0.82g). From January through March all fish were exposed to natural zooplankton as food source, whereas from April to September two cages were supplied daily with artificial food. The fish exposed to artificial supplementary diets exhibited significantly higher growth (17.5 Ā±0.98cm; 41.05 Ā±8.55g) than those in the control cages (15.02 Ā±0cm ; 23.5 Ā±0.84g), and exceeded the known values in pejerrey culture. The results suggest that the species potential growth is not fully achieved by common intensive methods and it can be improved by semi-intensive techniques. Accordingly a better understanding of the species nutritional requirements is needed to improve growth rates and enhance pejerrey culture. - Tesis de doctorado
Acceso Abierto Zooplancton de ambientes acuĆ”ticos de la cuenca del rĆo Salado (Buenos Aires): estudio de relaciones interespecĆficas y principales factores de control mediante experiencias de laboratorio y microcosmos(2015) Ferrando, Noelia SoledadEn el desarrollo de esta tesis se han cultivado y establecido las tasas de crecimiento de dos especies de algas clorofĆceas comĆŗnmente utilizadas como cultivos en laboratorio (Chlorella vulgaris y Scenedesmus acutus) y en experimentos con organismos herbĆvoros por ser. Se ajustĆ³ y optimizĆ³ la tĆ©cnica de recuento digitalizado de cĆ©lulas algales de manera de hacer mĆ”s eficiente el procesamiento de datos en la fase de experimentaciĆ³n y se relacionĆ³ la densidad del alga con la turbidez mediante un modelo lineal que permitiĆ³ el monitoreo inmediato de los cultivos, siendo una tĆ©cnica innovadora y con la posibilidad de ampliar su utilizaciĆ³n a otras especies de algas. Se han cultivado y establecido la tasa de crecimiento de algunas de las especies de rotĆferos y cladĆ³ceros presentes en las lagunas y rĆos pampeanos (Brachionus plicatilis, B. calyciflorus, Euchlanis dilatata, Plationus patulus y Asplanchna sieboldii entre los rotĆferos y Moina macrocopa, Macrothrix triserialis, Alona glabra y Simocephalus vetulus entre los cladĆ³ceros). Los valores obtenidos se relacionaron con la importancia numĆ©rica y frecuencia de estas especies en la naturaleza, explicando cĆ³mo algunas son dominantes mientras que otras sĆ³lo se presentan en determinadas Ć©pocas del aƱo. La cepa de B. plicatilis obtenida en el rĆo Salado muestra una destacada plasticidad frente a diversos niveles de conductividad que junto a su elevada tasa de crecimiento poblacional le posibilitan ser protagonista destacado en el zooplancton ya que alcanza elevadas densidades en la mayorĆa de los sectores lĆ³ticos de la cuenca y en ciertas ocasiones en los ambientes lĆ©nticos que pertenecen a la misma. AsĆ, se han analizado mediante experiencias de laboratorio y microcosmos cĆ³mo afectan los cambios de salinidad y temperatura al representante mĆ”s conspicuo de estos cuerpos de agua. Se evaluĆ³ la respuesta de Brachionus plicatilis ante la disminuciĆ³n y aumento de conductividad, generando rangos y Ć³ptimos en laboratorio que coincidieron con aquĆ©llos observados en las poblaciones naturales de la regiĆ³n (conductividad mĆnima de 2 mS/cm y Ć³ptimos entre los 5 y 8 mS/cm), demostrĆ”ndose asĆ que la variaciĆ³n genĆ©tica en cada cepa de esta especie es un factor clave para entender cĆ³mo Ć©sta responde ante un disturbio determinado segĆŗn su distribuciĆ³n geogrĆ”fica, poniendo en evidencia la importancia de conocer entonces estos parĆ”metros para las cepas locales. Para la misma especie se evaluĆ³ su desarrollo poblacional en respuesta a un cambio de temperatura. Los picos observados en la densidad para las poblaciones naturales de esta especie durante las temporadas de primavera-verano, muestran su preferencia por las temperaturas cĆ”lidas (25ĀŗC). Sin embargo, a nivel experimental pudo demostrarse que, en condiciones Ć³ptimas de salinidad esta especie tambiĆ©n puede soportar temperaturas menores (15Ā°C) manteniendo una poblaciĆ³n con menor densidad a lo largo del tiempo. Finalmente se evaluĆ³ el efecto de pastoreo sobre el alga C. vulgaris por separado para especies de rotĆferos (B. plicatilis), copĆ©podos calanoideos (Notodiaptomus incompositus) y cladĆ³ceros (Moina micrura, Diaphanosoma birgei y Simocephalus vetulus) para Ć©stos Ćŗltimos en presencia y ausencia de vegetaciĆ³n sumergida. Se relacionĆ³ la biomasa de las distintas especies con su consumo y encontrĆ”ndose una relaciĆ³n con los hĆ”bitos alimentarios de cada una de las especies, demostrando que M. micrura es un filtrador mĆ”s eficiente respecto a S. vetulus y B. plicatilis. El copĆ©podo N. incompositus a pesar de ser un raptor que debe capturar las partĆculas presentĆ³ valores similares a los de menor eficiencia filtradora, demostrando que este mĆ©todo de alimentaciĆ³n no constituye una desventaja. El rotĆfero B. plicatilis, a pesar de ser catalogado como filtrador poco eficiente, ha demostrado que con equivalente biomasa tiene una capacidad de consumo similar a los organismos de mayor porte como S. vetulus y N. incompositus, evidenciando de esta manera que es una especie a tener en cuenta a la hora de evaluar su efecto sobre el fitoplacton en los ecosistemas naturales ya que como se ha mencionado anteriormente es una especie que en la naturaleza puede alcanzar altas densidades en condiciones favorables. - ArtĆculo
Acceso Abierto Population ecology of Sinelobus stanfordi (Crustacea: Tanaidacea) in a temperate southern microtidal estuary(2015) Ferreira, Ana Clara; Ambrosio, Eugenia; Rodrigues CapĆtulo , AlbertoSinelobus stanfordi is a tanaidacean of worldwide distribution of considerable significance within coastal ecosystems. The aim of this research was to provide essential information on the poorlyknown population biology of this species. Benthic samples were taken seasonally from winter 2005 through summer 2007 along 155 km of shoreline within the RĆo de la Plata Estuary, Argentina. The density of this tanaidacean was higher in vegetated than in bare sediments. The smaller individuals flourished in spring and summer, whereas the larger mature members prevailed in the cooler seasons. Females were always twice as abundant as males. Copulatory females, with 18 Ā± 8 eggs each, were collected during all the seasons. Five cohorts were distinguished by the von Bertalanffy growth function. This research represents a baseline investigation for future studies on the population dynamics of S. stanfordi both in this estuary and in other places where this species is found. - ArtĆculo
Embargado Influence of El NiƱo Southern Oscillation phenomenon on coastal phytoplankton in a mixohaline ecosystem on the southeastern of South America: RĆo de la Plata estuary(2015) Sathicq, MarĆa BelĆ©n; Bauer, Delia Elena; GĆ³mez, 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 RĆo 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 NiƱo phases. Cyanobacteria were more abundant in the neutral periods, Chlorophyceae dominated La NiƱa phase while Bacyllariophyceae dominated El NiƱo. However, no complete replacement of species between cycles was observed. The results obtained were highly variable due to the inherent natural variability of the RĆo de la Plata, emphasized by the anthropogenic impact in this area.