Muestreo intensivo del zooplancton en el sector inferior del Río Salado (Bs. As.) durante la ejecución de una obra hidráulica (original) (raw)
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ABSTRACT. The objective of this study was to investigate changes occurred in the structure and dynamics of zooplankton community during dredging works made in the lower sector of Salado River (Buenos Aires, Argentina). The samples were taken before and during the extraction of a river restriction and the replacement of a bridge at one site upstream and other downstream of this hydraulic modification. The dredging works were made during low water period. Zooplankton samples were obtained filtering volumes of 10 l extracted at three points of a transect in the river channel (both banks and the middle of the course) during 14 weeks (weekly from March to June). Physical and chemical parameters were measured in situ with a multimeter. The conductivity de-creased from 12,000 μS/cm (March-April) to 6,000 μS/cm (April-June). The zooplankton assem-blages were correlated with factors such as conductivity, turbidity, water temperature, and phyto-plankton density. Tintinids (Tintinnidium fluviatile and Codonella cratera) prevailed with high sa-linity whereas rotifers (Brachionus plicatilis and Keratella tropica, among others) dominated later. Microcrustaceans were scarce related to the conductivity of the river. The analyzed sites showed similar composition and abundance of zooplankton during all sampling period. We can assume that the effects of dredging works in low water conditions cause minimal downstream perturba-tions on zooplankton community.
En el desarrollo de esta tesis se han cultivado y establecido las tasas de crecimiento de dos especies de algas clorofíceas comúnmente utilizadas como cultivos en laboratorio (Chlorella vulgaris y Scenedesmus acutus) y en experimentos con organismos herbívoros por ser. Se ajustó y optimizó la técnica de recuento digitalizado de células algales de manera de hacer más eficiente el procesamiento de datos en la fase de experimentación y se relacionó la densidad del alga con la turbidez mediante un modelo lineal que permitió el monitoreo inmediato de los cultivos, siendo una técnica innovadora y con la posibilidad de ampliar su utilización a otras especies de algas. Se han cultivado y establecido la tasa de crecimiento de algunas de las especies de rotíferos y cladóceros presentes en las lagunas y ríos pampeanos (Brachionus plicatilis, B. calyciflorus, Euchlanis dilatata, Plationus patulus y Asplanchna sieboldii entre los rotíferos y Moina macrocopa, Macrothrix triserialis, Alona glabra ...
Augmdomus, 2013
Contrariwise to the principles for the conservation of marine and terrestrial biotic resources, in the conservation of water resources, the biotic components such as the plankton species are dismissed. Few species of the thousands identified in this community are included in lists of endangered or threatened species by the International Union for Conservation of Nature (IUCN). Therefore, globally, the plankton components are excluded from any particular type of protection. Since the 1990s, prestigious researchers in the field of ecology and biogeography have emphasized the need to recognize biodiversity in the ecosystem functioning. In this sense, some questions could be formulated: Do aquatic organisms, especially plankton, deserve to be considered conservation targets? Is the preservation of the ecological integrity of water bodies enough protection for their conservation? The Salado River basin, located in the province of Buenos Aires, transports, during floods, excess of water and nutrients to the Samborombón bay (a Ramsar site). In spite of the occurrence of droughts and floods periods, with changes in salinity, and the impacts mainly of agriculture and hydraulic works, the water bodies maintain an acceptable degree of conservation and biodiversity. The plankton structure is dominated by unicellular chlorophytes, Brachionidae rotifers, Tintinnidae ciliates in the lower sector of the river and by crustaceans in zones associated with lentic environments. The community is complex, resilient and integrated by more than 300 species. The presence of key species would allow the maintenance of the ecosystem service function of this river. We propose to apply in the lowland rivers the multiscale concept of territorial unity, within the riverine landscape concept, which includes compositional conservation (Biodiversity) and functional conservation (Ecological Integrity).
Aspectos ecológicos del zooplancton en cuerpos de agua de Venezuela
Memorias del Instituto de Biología Experimental, 2012
La comunidad zooplanctónica constituye un eslabón clave en la trama trófica de los lagos y embalses, por lo que su estudio es imprescindible para poder establecer pautas en el manejo y usos de estos cuerpos de agua. Es por ello que el Laboratorio de Limnología ha adelantado estudios sobre esta comunidad en lagos y embalses venezolanos, a fin de establecer su composición y sus patrones de distribución, abundancia y biomasa. A través de estos estudios, en los que se han usado diversas herramientas, como las relaciones talla-peso y la taxonomía molecular, han podido establecerse cuáles son los factores que afectan las variaciones espaciales y temporales del zooplancton en cuerpos de agua de Venezuela, entre los que se cuentan las variaciones de las condiciones fisicoquímicas (temperatura, oxígeno disuelto, otros) y la disponibilidad de alimento, además de los impactos antrópicos en las respectivas cuencas de drenaje.
2014
Aspects of the zooplankton community were related to water quality in the Cataniapo River along an alteration gradient. The overall density of organisms was 1.55 org l - 1. A total of 23 rotifer taxa were identified, with the dominant being Bdelloidea, Trichocerca, Lecane and Lepadella. Cladocera were represented by two genera: Bosminopsis and Chydorus. Copepods were dominated by nauplii. Richness and diversity were 26 spp. and 2.26 respectively. Conglomerate analysis of zooplankton density showed a grouping between the middle and lower river sectors and zones of greater agricultural activity. Temporarily, samples taken during the lowering of the waters and at lowest water levels were highly associated. The density of the zooplankton community was significantly affected by the hydrological fluctuations, especially in the lower sector of the river. Zooplankton density was positively related to pH, water transparency and nutrient concentrations and negatively with heavy metal concentr...
Los aportes de agua dulce son determinantes en la circulación, estructura hidrográfica y patrones de productividad en sistemas estuarinos. El objetivo de este trabajo fue determinar el grado al cual la estructura de la comunidad zooplanctónica del complejo de fiordos Baker/Martínez, Región de Aysén, responde a cambios espaciales en las condiciones hidrográficas durante Febrero de 2013, estación de máxima descarga de los ríos Baker y Pascua. La comunidad de zooplancton estuvo compuesta por copépodos (Lucicutia sp, Oncaea sp, Acartia sp, entre otros), anfípodos, sifonóforos, poliquetos, quetognatos (Sagitta sp). Al comparar dos localidades, una externa y otra cercana a la desembocadura del río Baker, se observó presencia de los mismos grupos, aunque las abundancias relativas difirieron entre localidades. Esto produjo una separación entre localidades, pero no entre estratos de profundidad, cuando se aplicó un análisis de ordenación multivariado. El análisis de redundancia basado en dis...
Zooplancton De Aguas De Lastre De Buques Que Arriban Al Sistema De Maracaibo, Venezuela
2018
Las aguas de lastre son reconocidas mundialmente como uno de los principales medios de transporte de las especies invasoras. El sistema de Maracaibo es un gran estuario navegado constantemente por grandes barcos debido al comercio petrolero y sus derivados, esto representa un riesgo constante de invasion. Por ello, en esta investigacion se planteo como objetivo identificar las especies zooplanctonicas potencialmente invasoras en el sistema de Maracaibo a traves de las aguas de lastre. Para la toma de muestras se realizaron diez visitas a embarcaciones durante los anos 2012-2013, la toma de muestra se realizo con la ayuda de una red de plancton (apertura del poro de la malla = 150 µm), la cual fue introducida a traves de las escotillas ubicadas en cubierta. Como resultado se registraron 72 taxones, siendo el mas representativo del zooplancton Acartia tonsa , seguido de acaros marinos pertenecientes a la familia Halacaridae, ambos pertenecientes al Phylum Arthropoda, y organismos del ...
The surface zooplankton abundances, sea surface temperature and wind speed in slick and rough surface areas were compared south of Coquimbo Bay on November 7, 8 and 9, 2001. The presence of rough and slick surfaces on the bay was influenced by the wind conditions during sampling hours, demonstrating that increasing the speed steadily over 6 m s-1 slick and rough areas disappeared, giving a ripple appearance to sea surface. On the first two days of study, thermal structure of slicks areas was different from the rough ones. On the last day, temperature was higher with no differences between both surfaces types, and greater depth of the mixed layer, due to increasing wind speed. The organisms captured were holoplanktonic crustaceans, meroplankton benthopelagic peracarids, fish larvae and eggs, gelatinous zooplankton and gastropod and bivalve mollusks. On the first two days of study, most of zooplanktonic groups had greater abundance in slick surfaces, with significant differences between slick and rough areas in the case of barnacle cypris larvae and the euphausiid Nyctiphanes simplex. It was concluded that surface zooplankton caught in Coquimbo Bay, tend to aggregate in rough or slick surfaces, depending on their adaptive characteristics and behaviour.