National University of Comahue

About: National University of Comahue is a education organization based out in Neuquén, Argentina. It is known for research contribution in the topics: Population & Species richness. The organization has 2242 authors who have published 4498 publications receiving 87157 citations. The organization is also known as: UNCOMA & UNCo.

Ecological Stoichiometry of the Mountain Cryosphere

Abstract: Roughly 10% of the Earth’s surface is permanently covered by glaciers and ice sheets and in mountain ecosystems, this proportion of ice cover is often even higher. From an ecological perspective, ice-dominated ecosystems place harsh controls on life including cold temperature, limited nutrient availability, and often prolonged darkness due to snow cover for much of the year. Despite these limitations, glaciers and perennial snowfields still support diverse, primarily microbial communities, though macroinvertebrates and vertebrates are also present. The availability and mass balance of key elements [(carbon (C), nitrogen (N), phosphorous (P)] are known to influence the population dynamics of organisms, and ultimately shape the structure and function of ecosystems worldwide. While considerable attention has been devoted to patterns of existing biodiversity in mountain cryosphere-influenced ecosystems, the ecological stoichiometry of these habitats has been less studied. Understanding this emerging research arena is particularly pressing in light of the rapid recession of glaciers and perennial snowfields worldwide. In this review, we synthesize existing knowledge of ecological stoichiometry, nutrient availability, and food webs in the mountain cryosphere (specifically glaciers and perennial snowfields). We use this synthesis to develop more general understanding of nutrient origins, distributions, and trophic interactions in the mountain cryosphere. We focus our efforts on three major habitats: glacier surfaces (supraglacial), beneath glaciers (subglacial), and adjacent downstream habitats (i.e., glacier-fed streams and lakes). We compare nutrient availability in mountain cryosphere habitats to comparable habitats on continental ice sheets (e.g., Greenland and Antarctica) and show that, in general, nutrient levels are substantially different between the two. Next, we discuss how ongoing climate warming will alter nutrient and trophic dynamics in mountain glacier-influenced ecosystems. We conclude by highlighting the pressing need for future studies to understand spatial and temporal stoichiometric variation in the mountain cryosphere, ideally with direct comparisons to continental ice sheets, before these imperiled habitats vanish completely.

Differential hypogeous sporocarp production from Nothofagus dombeyi and N. pumilio forests in southern Argentina

Abstract: Mycorrhizal fungi that form hypogeous sporocarps are an important component of the temperate forest soil community. In many regions, such as the Nothofagus forest in the Patagonian Andes, this group of fungi has been poorly studied. Here we examined the spring and autumn commu- nity composition of ''sequestrate fungi'', based on sporocarp production in pure forests of Nothofagus dombeyi (evergreen) and N. pumilio (deciduous). We investigated the possible relationships between these communities and environmental factors over 2 y. The rarefaction curves and the minimal richness estimates converged at nearly the same level for each forest type, and the asymptotes suggested that the sampling effort was sufficient to capture most of the hypogeous sporocarp richness in these forest stands. In total 27 species were recovered. Basidiomycota, Ascomycota and Glomeromycota respectively accounted for nine, two and one genera. Species richness of hypogeous sporocarps varied in relation to forest type but not to season (fall and spring), whereas sporocarp biomass varied according to an interaction between season and forest type. Species richness and sporocarp biomass were positively correlated with rainfall and negatively correlated with altitude. In addition sporo- carp species richness was positively related to number of trees per transect. We found that two different forest stands, each dominated by different species of Nothofagus, exhibited different hypogeous sporocarp communities.

Prenatal exposure to pesticides: analysis of human placental acetylcholinesterase, glutathione S-transferase and catalase as biomarkers of effect.

Abstract: Pre- and perinatal exposure to pesticides is deleterious on foetal and neonatal development, but information regarding possible effects on environmental low-dose exposure to pesticides is scarce. Most epidemiological studies of the health effect of pesticides have been based on self-reported information. However, detailed information on past pesticide use is difficult to reconstruct. This is a current study conducted among pregnant mothers attending a delivery care and perinatal programme at a public hospital. The study investigates biomarkers of early effects in placentas from women living in an area with an intensive use of pesticides in the northern part of Patagonia, province of Rio Negro, Argentina, and it assesses the consistency of the information provided by self-reports. The study confirms that placental acetylcholinesterase and catalase activities are significantly associated with periods of organophosphorus pesticides application, while glutathione S-transferase is not affected. We found a positive correlation between environmental exposure to organophosphorus pesticides and carbamate insecticides and newborn head circumference. The findings provide a further indication of a link between placenta acetylcholinesterase and catalase activity and prenatal exposure to pesticides in population studies. Both placenta enzymes may be used as biomarkers in health surveillance programmes for early diagnosis of exposure related alterations produced by organophosphorus pesticides and carbamate pesticides.

Conspecifics Enhance Attraction of Vespula germanica (Hymenoptera: Vespidae) Foragers to Food Baits

Abstract: Local enhancement has been shown to occur in the social wasp Vespula germanica (F.), a species that feeds on live insects as well as on dead animals. Some studies suggest local enhancement is based on sight, whereas others suggest that odors emanating from wasp bodies are more important in attracting conspecifc workers to a food source. We studied whether the attraction of V. germanica foragers to meat baits increases by the addition of live conspecific foragers and analyzed which cues (olfactory and visual) elicit this attraction. Our results show that the combination of meat and wasps strongly enhances the attraction of conspecific foragers. Presenting both visual and olfactory cues together leads to a wasp response that is much greater than if isolated visual or isolated olfactory cues were added, suggesting some synergistic action of both cues.

Body shape variation of three species of Percichthys in relation to their coexistence in the Limay River basin, in northern Patagonia

Abstract: We describe morphological variation within and among three species of Percichthys (Perciformes, Percichthyidae) inhabiting two reservoirs within a single river drainage (Limay River) in Argentina. Two small-mouthed percas’, P. vinciguerrai and P. trucha were found in both reservoirs (Alicura and Piedra del Aguila), and a third species, the large-mouthed perca, P. colhuapiensis, was found in Piedra del Aguila. There was some specialization in diet where the three species coexisted. The large-mouthed perca ate a higher proportion of large prey (>25 mm) and a smaller proportion of small prey (< 15 mm) than did the small-mouthed species, suggesting some diet specialization based on prey size. Percichthys trucha and P. vinciguerrai had smaller gapes, as indicated by shorter heads and jaws, and narrower mouths, in Piedra del Aguila where they coexisted with the large-mouthed species, than in Alicura where the competitor was virtually absent. Thus the direction of morphological changes in trophic-related characters in P. trucha and P. vinciguerrai is consistent with the hypothesis of character shift due to interspecific competition.