Distribuci\uf3n espacio-temporal de larvas de Chironomidae (Diptera) en un arroyo andino (Uspallata, Mendoza, Argentina)

Se realizó un estudio sobre la composición larval de la familia Chironomidae en un arroyo andino en la localidad de Uspallata (Mendoza, Argentina). Se realizaron muestreos estacionales durante un ciclo anual completo (2001/2002) en tres sitios, siguiendo un gradiente altitudinal. Se midieron variables físico-químicas en campo y laboratorio. La relación entre presencia y abundancia de quironómidos y parámetros ambientales se exploró mediante un análisis de Correspondencia Canónica. Se identificaron siete géneros pertenecientes a cuatro subfamilias: Chironominae, Orthocladiinae, Podonominae y Tanypodinae. Orthocladiinae fue la subfamilia que tuvo mayor riqueza genérica (Cricotopus van der Wulp, Onconeura Andersen & Saether y Parametriocnemus Goetghebuer), densidad y frecuencia de aparición a nivel estacional y espacial. Podonominae (Podonomus Philippi y Podonomopsis Brundin) se halló únicamente en SA mientras que Chironominae (Polypedilum Kieffer) estuvo presente en UD. Tanypodinae (Pentaneura Philippi) se encontró en los tres sitios de muestreo aunque con una densidad menor. Se detectó incremento de la conductividad y temperatura del agua, y disminución del tamaño del sustrato desde SA a UD, lo que coincide con la desaparición de Podonomus y Podonomopsis y la aparición de Polypedilum hacia UD. De este estudio se concluye que el sistema presenta baja riqueza genérica comparada con otros sistemas montañosos de Argentina

Distribución espacio-temporal de larvas de Chironomidae (Diptera) en un arroyo andino (Uspallata, Mendoza, Argentina) Spatial and temporal distribution of larvae of Chironomidae (Diptera) in an Andean stream (Uspallata, Mendoza, Argentina)

Se realizó un estudio sobre la composición larval de la familia Chironomidae en un arroyo andino en la localidad de Uspallata (Mendoza, Argentina). Se realizaron muestreos estacionales durante un ciclo anual completo (2001/2002) en tres sitios, siguiendo un gradiente altitudinal. Se midieron variables físico-químicas en campo y laboratorio. La relación entre presencia y abundancia de quironómidos y parámetros ambientales se exploró mediante un análisis de Correspondencia Canónica. Se identificaron siete géneros pertenecientes a cuatro subfamilias: Chironominae, Orthocladiinae, Podonominae y Tanypodinae. Orthocladiinae fue la subfamilia que tuvo mayor riqueza genérica (Cricotopus van der Wulp, Onconeura Andersen & Saether y Parametriocnemus Goetghebuer), densidad y frecuencia de aparición a nivel estacional y espacial. Podonominae (Podonomus Philippi y Podonomopsis Brundin) se halló únicamente en SA mientras que Chironominae (Polypedilum Kieffer) estuvo presente en UD. Tanypodinae (Pentaneura Philippi) se encontró en los tres sitios de muestreo aunque con una densidad menor. Se detectó incremento de la conductividad y temperatura del agua, y disminución del tamaño del sustrato desde SA a UD, lo que coincide con la desaparición de Podonomus y Podonomopsis y la aparición de Polypedilum hacia UD. De este estudio se concluye que el sistema presenta baja riqueza genérica comparada con otros sistemas montañosos de Argentina.<br>A study was conducted on the larval composition of the family Chironomidae in an Andean stream in Uspallata locality (Mendoza, Argentina). Seasonal samplings were performed over a full annual cycle (2001/2002) at three sites, along an altitudinal gradient. Physical and chemical variables were measured in both the field and the laboratory. Relationship between presence and abundance of chironomids and environmental parameters was explored using a Canonical Correspondence analysis. Seven genera were identified, corresponding to four subfamilies: Chironominae, Orthocladiinae, Podonominae and Tanypodinae. The subfamily Orthocladiinae had the highest genus richness (Cricotopus van der Wulp, Onconeura Andersen & Saether and Parametriocnemus Goetghebuer), density and frequency of occurrence at seasonal and spatial levels. Podonominae (Podonomus Philippi and Podonomopsis Brundin) was found only at SA, whereas Chironominae (Polypedilum Kieffer) was present at UD. Tanypodinae (Pentaneura Philippi) was found at all three sampling sites, although in lower density. Increased conductivity and water temperature and decreased substrate size were detected from SA to UD, coinciding with the disappearance of Podonomus and Podonomopsis and the appearance of Polypedilum toward UD. This study leads to the conclusion that the system presents low genus richness compared to other mountain systems of Argentina

Distribution of Macroinvertebrate assemblages along a saline wetland in harsh environmental conditions from Central-West Argentina

The goal was to examine how macroinvertebrate taxonomic richness and density respond to spatial-temporal changes and to the influence of water physicochemical characteristics along the Bañado Carilauquen (BC). Benthic samplings were conducted seasonally and environmental parameters were recorded in five reaches of the BC. Cluster analysis was applied to compare taxonomic richness among sites. Community structure and spatial-temporal variation were explored using logarithmic regression. CCA was applied to explore the relationship between species and environmental variables. A total of 36 taxa were identified, predominantly insects. A growing gradient of conductivity and hardness was registered between headwaters (HD; relatively soft waters) and outlet (OL; very hard and saline waters). Total density of taxa showed significant differences among sampling sites and climate seasons. A decline in richness and density was observed from HD to OL. The spatial conductivity gradient is the major factor modulating macroinvertebrate distribution along this saline arid wetland. With the exception of the headwaters, hard, eutrophic, polysaprobic and contaminated waters such of those of the BC represent critical conditions for the development of macroinvertebrate assemblages.Fil: Scheibler, Erica Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Ciocco, Nestor Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentin

The fate of endemic insects of the Andean region under the effect of global warming.

Three independent but complementary lines of research have provided evidence for the recognition of refugia: paleontology, phylogeography and species distributional modelling (SDM). SDM assesses the ecological requirements of a species based on its known occurrences and enables its distribution to be projected on past climatological reconstructions. One advantage over the other two approaches is that it provides an explicit link to environment and geography, thereby enabling the analysis of a large number of taxa in the search for more general refugia patterns. We propose a methodology for using SDM to recognize biogeographical patterns of endemic insects from Southern South America. We built species distributional models for 59 insect species using Maxent. The species analyzed in the study have narrow niche breadth and were classified into four assemblages according to the ecoregion they inhabit. Models were built for the Late Pleistocene, Mid-Holocene and Present. Through the procedure developed for this study we used the models to recognize: Late Pleistocene refugia; areas with high species richness during all three periods; climatically constant areas (in situ refugia); consistent patterns among in situ refugia, Pleistocene refugia and current distribution of endemic species. We recognized two adjacent Pleistocene refugia with distinct climates; four in situ refugia, some of which are undergoing a process of fragmentation and retraction or enlargement. Interestingly, we found a congruent pattern among in situ refugia, Pleistocene refugia and endemic species. Our results seem to be consistent with the idea that long-term climate stability is known to have a key role in promoting persistence of biodiversity in an area. Our Pleistocene and in situ refugia are consistent with refugia identified in studies focusing on different taxa and applying other methodologies, showing that the method developed can be used to identify such areas and prove their importance for conservation

Ecoregions and resulting Pleistocenic refugia.

<p>(a) Ecoregions: Brown- Valdivian Temperate Forest (VTF), green- Chilean Matorral (CM), red- Patagonian Steppe (PS), blue- Magellanic Subpolar Forest (MSF). (b) Late Pleistocenic refugia: Brown- Valdivian Temperate Forest (VTF) refuge, black- Magellanic Subpolar Forest (MSF) refuge, green- overlapping areas between the two refugia, grey- ice sheet.</p

Valdivian Temperate Forest (VTF).

<p>Insect-rich area maps (IAMs), maps with areas where more than 80% of the species models matched (24 or more of the 31 species). (a) Late Pleistocene with the ice sheet. (b) Mid Holocene. (c) Present. (d) <i>in situ</i> refugia (IRM), map with the area where 80% or more of the species have found suitable conditions over all three time periods.</p

Chilean Matorral (CM).

<p>Insect-rich area maps (IAMs), maps with areas where more than 80% of the species models matched (8 or more of the 10 species). (a) Late Pleistocene with the ice sheet. (b) Mid Holocene. (c) Present. (d) <i>in situ</i> refugia (IRM), map with the area where 80% or more of the species have found suitable conditions over all three time periods.</p

Magellanic Subpolar Forest (MSF).

<p>Insect-rich area maps (IAMs), maps with areas where more than 80% of the species models matched (8 or more of the 10 species). (a) Late Pleistocene with the ice sheet. (b) Mid Holocene. (c) Present. (d) <i>in situ</i> refugia (IRM), map with the area where 80% or more of the species have found suitable conditions over all three time periods.</p

Boxplots of precipitation related variables.

<p>Comparison of variables with high discrepancy for the Magellanic Subpolar Forest (MSF) and the Valdivian Temperate Forest (VTF) Late Pleistocene refugia (left MSF- right VTF). Boxes represent the upper (in green) and lower (in brown) 25% of the scores and are separated by the median. Units of the y-axes are in brackets beside chart headings.</p