The Application of Chironomid Pupal Exuvial Technique (CPET) for Ecological Analysis in a Neotropical Large River System

This field ecological study, based on the chironomid pupal exuvial technique (CPET), is new for the Paraná River and proposes an efficient tool to be used in future ecological approaches and biomonitoring. Drifting of pupal exuviae in a river-floodplain system of the Middle Paraná River floodplain was represented by 34 Chironomidae taxa, being the characteristic association obtained from the CPET: Lopescladius, Onconeura, Paralauterborniella, Polypedilum, and Harnischia complex. Diversity, richness, dominance, total density, and density of dominant taxa were different between the longitudinal and lateral dimensions but not between hydrologic phases, with a greater diversity and richness in the main channel of the river and higher density and dominance in floodplain habitats. The species turnover is the dominant process in structuring studied assemblages in spatial and temporal analysis, increasing in the floodplain habitats and in low-water phase. The results obtained showed that drifting exuviae in the longitudinal axis were coming from different assemblages and environments of a wider area (regional), while exuviae recorded in the connections of the floodplain environments in the lateral dimension could reflect the local assemblages. We demonstrated the ecological value of CPET studies to interpret the attributes of Chironomidae assemblage in river-floodplain systems of large rivers in an integrated way.Instituto de Limnología "Dr. Raúl A. Ringuelet

The Application of Chironomid Pupal Exuvial Technique (CPET) for Ecological Analysis in a Neotropical Large River System

This field ecological study, based on the chironomid pupal exuvial technique (CPET), is new for the Paraná River and proposes an efficient tool to be used in future ecological approaches and biomonitoring. Drifting of pupal exuviae in a river-floodplain system of the Middle Paraná River floodplain was represented by 34 Chironomidae taxa, being the characteristic association obtained from the CPET: Lopescladius, Onconeura, Paralauterborniella, Polypedilum, and Harnischia complex. Diversity, richness, dominance, total density, and density of dominant taxa were different between the longitudinal and lateral dimensions but not between hydrologic phases, with a greater diversity and richness in the main channel of the river and higher density and dominance in floodplain habitats. The species turnover is the dominant process in structuring studied assemblages in spatial and temporal analysis, increasing in the floodplain habitats and in low-water phase. The results obtained showed that drifting exuviae in the longitudinal axis were coming from different assemblages and environments of a wider area (regional), while exuviae recorded in the connections of the floodplain environments in the lateral dimension could reflect the local assemblages. We demonstrated the ecological value of CPET studies to interpret the attributes of Chironomidae assemblage in river-floodplain systems of large rivers in an integrated way.Instituto de Limnología "Dr. Raúl A. Ringuelet

The Application of Chironomid Pupal Exuvial Technique (CPET) for Ecological Analysis in a Neotropical Large River System

This field ecological study, based on the chironomid pupal exuvial technique (CPET), is new for the Paraná River and proposes an efficient tool to be used in future ecological approaches and biomonitoring. Drifting of pupal exuviae in a river-floodplain system of the Middle Paraná River floodplain was represented by 34 Chironomidae taxa, being the characteristic association obtained from the CPET: Lopescladius, Onconeura, Paralauterborniella, Polypedilum, and Harnischia complex. Diversity, richness, dominance, total density, and density of dominant taxa were different between the longitudinal and lateral dimensions but not between hydrologic phases, with a greater diversity and richness in the main channel of the river and higher density and dominance in floodplain habitats. The species turnover is the dominant process in structuring studied assemblages in spatial and temporal analysis, increasing in the floodplain habitats and in low-water phase. The results obtained showed that drifting exuviae in the longitudinal axis were coming from different assemblages and environments of a wider area (regional), while exuviae recorded in the connections of the floodplain environments in the lateral dimension could reflect the local assemblages. We demonstrated the ecological value of CPET studies to interpret the attributes of Chironomidae assemblage in river-floodplain systems of large rivers in an integrated way.Instituto de Limnología "Dr. Raúl A. Ringuelet

Concentration and environmental fate of ivermectin in floodplain wetlands: an ecosystem approach

Ivermectin (IVM) is commonly used for broad control of endo- and ecto- parasites in cattle. In wetlands of the Parana Medio River, cattle has been treated repeatedly with IVM for years and concerns have been raised on possible presence of the drug in these ecosystems. A field study was conducted to assess concentration of IVM in two wetlands subjected to different cattle use and frequency of IVM injection. Concentration of IVM in roots of macrophytes, Chironomus sp., Coelotanypus sp., Brachymesia furcata (larvae), Dero sp., Hyalella sp., Hirudinea, Planorbidae, Boana pulchella (larvae), Aphyocharax anisitsi and Serrapinnus calliurus were shown for the first time. Total concentration of IVM in the wetlands, and concentration in cattle manure, sediment, water and macrophytes increased with the number of treated cattle and frequency of IVM injections. Accumulation of IVM in aquatic assemblages is alarming because these organisms fulfill a key role in food webs, constituting a serious risk to human health. Management strategies should be implemented by farmers to keep recently treated animals away from watercourses to reduce the introduction of IVM into aquatic systems.Fil: Mesa, Leticia Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Gutiérrez, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; ArgentinaFil: Montalto, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Perez, Vanina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; ArgentinaFil: Lifschitz, Adrian Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentin

Clave para la identificación de Chironomidae (Diptera) de la ecorregión Tributarios del río Paraná y Río de la Plata mediante la utilización de exuvias pupales

Chironomidae is one of the most important taxa in freshwater ecosystems. Pupal exuviae are used as a simple and rapid way to obtain ecological information on aquatic habitats and data on autecology and geographic distribution. The objective of this study was to develop a key for the identification of pupal Chironomidae from the ecoregion Tributaries of Paraná and Río de la Plata rivers, integrating information recently in the ecoregion with the knowledge available from previous publications. The study of the pupal exuviae allowed to expand the knowledge of the taxonomic richness and the distribution of genera and species previously registered. On the other hand, the application of the Chironomidae Pupal Exuviae Technique enabled a precise identification at the species/morphospecies level and a reduction in sampling time and sample processing, resulting efficient and less expensive. This key is the result of knowledge of the family in the ecoregion for several decades and constitutes a first contribution to the taxonomic knowledge of Chironomidae at the species level.Chironomidae es uno de los taxones más importantes de los ecosistemas de agua dulce. Las exuvias pupales se utilizan como una forma simple y rápida de obtener información ecológica sobre hábitats acuáticos y autoecología y distribución geográfica de las especies. El objetivo de este estudio fue elaborar una clave de identificación de pupas de Chironomidae presentes en los arroyos de la ecorregión Tributarios del río Paraná y Río de la Plata, integrando información relevada en estudios recientes, con el conocimiento disponible en publicaciones previas. El estudio de las exuvias pupales permitió ampliar el conocimiento de la riqueza taxonómica y la distribución de géneros y especies previamente registrados para la región. Por otro lado, la aplicación de la Técnica de Exuvias Pupales de Chironomidae posibilita identificaciones precisas a nivel de especie/morfoespecie y una reducción del tiempo de muestreo y procesamiento de las muestras resultando eficiente y menos costosa. Esta clave es el resultado del conocimiento de la familia en la ecoregión desde hace varias décadas y constituye un primer aporte al conocimiento taxonómico de Chironomidae a nivel de especie

Hábitos Alimentarios de Hyalella Curvispina Shoemaker, 1942 (Amphipoda: Gammaridea) en Ambientes Leníticos de la Llanura Aluvial del Río Paraná Medio

La asignación de los organismos a los grupos funcionales tróficos queda aún por resolver en la Región Neotropical ya que, generalmente se utilizan clasificaciones realizadas para especies de la Región Holártica. Así, Hyalella curvispina es citada como triturador, depredador, raspador y colector-recolector. El objetivo del trabajo fue determinar el grupo funcional trófico que integra H. curvispina. La hipótesis fue que H. curvispina consume preferentemente tejido vegetal, clasificándose en la categoría de triturador. Se recolectaron 30 individuos adultos para analizar su ingesta en tres ambientes leníticos durante el período abril-agosto del 2009. Los valores medios de las proporciones de cada ítem alimentario para los ambientes estudiados fueron: detritos 66,3%; tejido vegetal 28,2%; tejido animal 4,4% y algas 1,4%. Se encontraron diferencias significativas (p<0,01) en los ítems consumidos por los organismos entre las lagunas. No se observaron diferencias significativas en el consumo entre machos y hembras (p<0,01). Se concluye que H. curvispina integra el grupo funcional de los colectores recolectores, siendo además un triturador facultativo.Fil: Saigo, Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Marchese Garello, Mercedes Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Montalto, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin

Key for identification of pupal Chironomidae (Diptera) from the ecoregion Tributaries of Paraná and Río de la Plata rivers through the use of pupal exuviae

Chironomidae es uno de los taxones más importantes de los ecosistemas de agua dulce. Las exuvias pupales se utilizan como una forma simple y rápida de obtener información ecológica sobre hábitats acuáticos, autoecología y distribución geográfica de las especies. El objetivo de este estudio fue elaborar una clave de identificación de pupas de Chironomidae presentes en los arroyos de la ecorregión Tributarios del río Paraná y Río de la Plata, integrando información relevada en estudios recientes y con el conocimiento disponible en publicaciones previas. El estudio de las exuvias pupales permitió ampliar el conocimiento de la riqueza taxonómica y la distribución de géneros y especies previamente registrados para la región. Por otro lado, la aplicación de la Técnica de Exuvias Pupales de Chironomidae posibilita identificaciones precisas a nivel de especie/morfoespecie y una reducción del tiempo de muestreo y procesamiento de las muestras resultando eficiente y menos costosa. Esta clave es el resultado del conocimiento de la familia en la ecoregión desde hace varias décadas y constituye un primer aporte al conocimiento taxonómico de Chironomidae a nivel de especie.Chironomidae is one of the most important taxa in freshwater ecosystems. Pupal exuviae are used as a simple and rapid way to obtain ecological information on aquatic habitats and data on autecology and geographic distribution. The objective of this study was to develop a key for the identification of pupal Chironomidae from the ecoregion Tributaries of Paraná and Río de la Plata rivers, integrating information recently in the ecoregion with the knowledge available from previous publications. The study of the pupal exuviae allowed to expand the knowledge of the taxonomic richness and the distribution of genera and species previously registered. On the other hand, the application of the Chironomidae Pupal Exuviae Technique enabled a precise identification at the species/morphospecies level and a reduction in sampling time and sample processing, resulting efficient and less expensive. This key is the result of knowledge of the family in the ecoregion for several decades and constitutes a first contribution to the taxonomic knowledge of Chironomidae at the species level.Instituto de Limnología "Dr. Raúl A. Ringuelet

Diversity, phenology and voltinism of Chironomidae (Diptera): Neotropical streams as a study model

Studies of the relationships between the temporal variation of biological phenomena and environmental factors are essential to understanding the dynamics of communities. Phenology is a structuring element and, together with voltinism, is related to timing of reproductive activities. The aim of this study is to ascertain the structure and composition of the Chironomid assemblage and its emergence patterns in relation to the environmental variables through the use of the Chironomid pupal exuviae technique using the Neotropical streams as a model. The streams presented similar species compositions. The highest density of pupal exuviae was recorded during spring and the greatest richness in late summer and early autumn. Chironominae presented greater prevalence throughout the year with oscillations for Orthocladiinae and Tanypodinae. Chironominae and Tanypodinae presented emergence peaks in spring-summer and Orthocladiinae in autumn-winter. Rainfall, photoperiod and water and air temperatures structured the Chironomid assemblage, influencing emergence. Univoltine, bivoltine and multivoltine species were recorded. The species presented interspecific synchronization in emergence peaks at different times of the year.Fil: Zanotto Arpellino, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Rodriguez Catanzaro, Ludmila Noelia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Montalto, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Siri, Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Donato, Mariano Humberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

Dispersal traits as benthic invertebrate assemblage drivers in a neotropical large river

Metacommunity theory is a mechanistic framework that explains the interdependence of local factors and regional processes as community drivers. Recent evidence suggests that dispersal mode is a key trait that potentially affects metacommunity dynamics. We analyzed the distribution patterns of benthic macroinvertebrates with different dispersal modes in the Middle Paraná, a neotropical large river. We assessed the relative importance of local environmental conditions and regional spatial structure as assemblage drivers. Aquatic and aerial dispersers presented Clementsian and Gleasonian structures, respectively. For both groups, local environmental conditions influenced community assembly, and spatial structure (overland distances) also affected the distribution of aerial dispersers. Our study highlights that the role of spatial structure as a driver of benthic metacommunities depends on species’ dispersal modes. Aerial dispersers responded to regional spatial variables and it is likely that these organisms are also influenced by mass effects. Our results are consistent with current ideas of metacommunity dynamics in large rivers, where dispersal is not considered to limit the distribution of benthic organisms.Fil: Saigo, Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Marchese Garello, Mercedes Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Montalto, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentin

Diversity of chironomid larvae in a marginal fluvial wetland of the Middle Paraná River floodplain, Argentina

The diversity of chironomid larvae in relation to flooding and drought phases in a marginal fluvial wetland of the Middle Paraná River floodplain was analyzed. Four sampling stations in the right bank of the Tiradero Viejo River towards the interior of the marginal wetland were established: one at the riverside, and three more at 10, 30 and 40 m from the river. Bottom sediment samples were extracted during the hydrosedimentological cycle of 2001. A total of 25 taxa of Chironomidae were recorded. The values of taxonomic richness, density and diversity were higher in the marginal fluvial wetland than in the riverside, increasing when the wetland is disconnecting from the river. Polypedilum (Tripodura) spp., Polypedilum (Polypedilum) spp., Ablabesmyia (Karelia) spp., Coelotanypus sp., Monopelopia cf. boliekae, Goeldichironomus holoprasinus and Chironomus gr. decorus spp. were dominant in marginal wetlands. The results indicate that the variations in the hydrosedimentological regime, the degree of disconnection with the river and the progressive desiccation at each one of the stations of the marginal fluvial wetland are limitant factors in the distribution and abundance of aquatic chironomids. The different assemblages of Chironomidae were strongly conditioned by temporal changes related to the gradient of inundation-drought and to the hydroperiod dynamics.Fil: Montalto, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Paggi, Analia Constancia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin