Exploring Soil Bacterial Diversity in Relation to Edaphic Physicochemical Properties of High-altitude Wetlands from Argentine Puna.

High Andean wetlands, particularly those known as vegas or bofedales, are essential conservation ecosystems due to their significant contribution to ecosystem services. The soil microbial communities in these ecosystems play a crucial role in fundamental processes such as decomposition and nutrient cycling, sustaining life in the region. However, at present, these microbial communities are poorly understood. In order to contribute to this knowledge, we aimed to characterize and compare the microbial communities from soils of seven Argentine Puna vegas and to analyze their association with soil physicochemical characteristics. Proteobacteria (Gamma and Alphaproteobacteria) was the dominant phylum across all vegas, followed in abundance by Actinobacteriota, Desulfobacterota, and Chloroflexi. Furthermore, the abundance of specific bacterial families and genera varied significantly between the vegas; some of them can be associated with plant growth-promoting bacteria such as Rhodomicrobium in La Quebradita and Quebrada del Diablo, Bacillus in Antofalla and Las Quinuas. Laguna Negra showed no shared ASVs with abundance in genera such as Sphingomonas and Pseudonocardia. The studied vegas also differed in their soil physicochemical properties; however, associations between the composition of microbial communities with the edaphic parameters measured were not found. These results suggest that other environmental factors (e.g., geographic, climatic, and plant communities' characteristics) could determine soil microbial diversity patterns. Further investigations are needed to be focused on understanding the composition and function of microorganisms in the soil associated with specific vegetation types in these high-altitude wetlands, which will provide valuable insights into the ecological dynamics of these ecosystems for conservation strategies.

Patrones espaciales en comunidades de macroinvertebrados acuáticos de la Puna Argentina / Spatial patterns in communities of aquatic macroinvertebrates of Argentinean Puna

ResumenLos macroinvertebrados son un componente vital en los ecosistemas acuáticos, procesan materia orgánica y sirven de alimento para otros organismos como los peces o anfibios. En los sistemas altoandinos, y más específicamente en las vegas o bofedales de Argentina, el conocimiento de la diversidad acuática es escaso o nulo, lo que ha dificultado la interpretación de patrones espaciales a escalas regionales. Típicamente estos ecosistemas se sitúan entre los 3 200 y 5 200 m.s.n.m. en zonas con precipitaciones por debajo de los 300 mm anuales. En este trabajo se realizó la primera descripción cuantitativa de los patrones espaciales de diversidad y composición de macroinvertebrados acuáticos en siete vegas de la Puna Argentina, y su relación con las características del ambiente, de la vegetación circundante y las características físico-químicas del agua. Se recolectaron 3 131 individuos de macroinvertebrados acuáticos, los cuales fueron identificados en 25 taxa que pertenecen a 22 familias y 24 géneros. Entre las plantas vasculares se registraron un total de 62 especies, correspondiente a 20 familias, las graminoides cespitosas fueron la forma de vida más abundante seguida por plantas en cojín o tapete. A partir de un análisis estadístico de ordenamiento NMDS (Non-Metrical Multidimensional Scaling) se segregaron los sitios de muestreo de cada vega. Las vegas ubicadas más al oeste y al sur y con mayor temperatura del agua se agruparon sobre el eje 1, mientras que las vegas con mayor conductividad, sólidos totales disueltos, y concentración de sales en el agua lo hicieron sobre el eje 2. La temperatura del agua fue siempre mayor que la del aire, y no mostró un patrón claro de disminución con la altitud. La altitud no se correlacionó con la abundancia de los macroinvertebrados ni con la riqueza de las plantas. Las formas de vida de plantas como gramíneas dispersas, hierbas rastreras y postradas (que en muchos casos ingresan al cauce de agua) y plantas acuáticas fueron más abundantes en las vegas 4, 5 y 7 y estuvieron asociadas con ciertos taxa de macroinvertebrados que pertenecen a distintos grupos funcionales tróficos como colectores- filtradores, colectores- recolectores y raspadores. Finalmente, las variables de conductividad, sólidos totales disueltos y concentración de sales fueron más elevadas en la vega 6, asociadas a Bivalvia (colector-filtrador) y Hyalella (colector-recolector). A partir de estos resultados se evidencia que los macroinvertebrados presentaron patrones espaciales de diversidad y composición, siendo en primer lugar más importante su relación con la vegetación circundante y en segundo término con las características físico-químicas del agua en siete vegas de la Puna argentina.

AbstractThe macroinvertebrates are a vital component of freshwater ecosystems as they contribute to the process of organic matter while serving as food for other organisms such as fish and amphibians. Unfortunately, the knowledge of the aquatic diversity is poor in the high Andean systems (between 3 200 and 5 200 m.a.s.l. and rainfall below 300 mm per year), especially in the Argentinean peatbogs, a fact which has made difficult the interpretation of spatial patterns on a regional scale. The present study aimed to describe the composition of aquatic macroinvertebrates in seven peatbogs in the Argentinean Puna, and to analyze for the first time their spatial patterns. For this, we studied the relationship of these organisms with the environment, and obtained information about the surrounding vegetation and water physico-chemical characteristics. A total of 3 131 specimens of aquatic macroinvertebrates were collected, representing 25 taxa belonging to 22 families and 24 genera. In addition, 62 species of vascular plants were recorded, belonging to 20 families. The most abundant life form were the tufted grasses, followed by cushions. By using an NMDS (Non-Metrical Multidimensional Scaling) statistical analysis, the sampling sites were ordered in each peatbog as follows. The peatbogs located furthest West and South with higher water temperature were grouped on axis 1, whereas those with higher conductivity, whole water dissolved solids and salt concentration were grouped on axis 2. The water temperature was higher than air temperature at all times, and we found no association between temperature and altitude. The altitude had no correlation with the abundance of macroinvertebrates or with plant richness. Life forms such as scattered graminoids, trailing and prostrate herbs (in many cases they get into the channel) and aquatic plants were more abundant in peatbogs 4, 5 and 7 and they had a correlation with some macroinvertebrates belonging to functional trophic groups such as filter-collectors, collectors and scrapers. Finally, conductivity, whole dissolved solids and salt concentration had their highest value in peatbog 6, where Bivalvia (filter-collector) and Hyalella (collector) were also found. The results obtained attest that these macroinvertebrates displayed diversity and composition spatial patterns, the most important feature being their relationship with the surrounding vegetation, and to a lesser extent, with the physical and chemical traits of water in seven fertile lowlands in the Argentinean Puna. Rev. Biol. Trop. 64 (2): 747-762. Epub 2016 June 01.