http://repositorio.unnoba.edu.ar/xmlui/handle/23601/110 Laboratorio de Limnología/Ecología Microbiana Acuática Sat, 25 Apr 2026 05:44:38 GMT 2026-04-25T05:44:38Z http://repositorio.unnoba.edu.ar/xmlui/handle/23601/926 Water quality and diarrhoeagenic Escherichia coli detection in surface Pampean aquatic systems Many surface water systems are impacted by point source pollution from sewage discharges and industrial wastes, as well as diffuse pollution from agriculture and livestock farming, inducing a potential biohazard to human, animal, and environmental health. This study aimed to determine the presence of diarrhoeagenic Escherichia coli (DEC) pathotypes and their antibiotic resistance, as well as the bacteriological, physical, and chemical water quality conditions in two Pampean peri-urban rivers (Rojas and Salado rivers, Buenos Aires, Argentina) used for recreation. Additionally, we explored the impact of the surrounding land use on the water quality. In the Rojas (R) and Salado (S) rivers, wastewater discharges from treatment plants increased nutrient content and coliform abundances at specific sampling sites (R2 and S3) and downstream (R3 and S4, respectively). Coliform abundances correlated with ammoniacal nitrogen concentrations, both exceeding recreational use guidelines. Out of 36 samples positive for DEC virulence factors, 11 DEC strains were isolated (5 enteroaggregative, 3 enteropathogenic, 1 shigatoxigenic-stx1/stx2, 1 shigatoxigenic-stx2, 1 hybrid enteroaggregative-enterotoxigenic). Six strains were resistant to one or more antibiotics. Our results suggest that differences in E. coli pathotypes between the two rivers and the water quality of each sampling site are linked to the surrounding land use, evidencing both diffuse and point source pollution. Wed, 26 Feb 2025 00:00:00 GMT http://repositorio.unnoba.edu.ar/xmlui/handle/23601/926 2025-02-26T00:00:00Z http://repositorio.unnoba.edu.ar/xmlui/handle/23601/478 Phytoplankton in Antarctic lakes: biodiversity and main ecological features Antarctica holds a great number of inland lakes whose characteristics vary from ultra-oligotrophic to hypereutrophic, and from freshwater to hypersaline. The harsh conditions in these ecosystems (extremely low temperatures, large annual variation in solar radiation, light limitation below the ice) account for adaptive strategies of the selected phytoplankton species; some of them are mixotrophy, formation of resistant cysts, starch accumulation, pigment adaptation and motility. Algal richness is comparatively lower than in other parts of the world, although molecular studies are now revealing a biodiversity much higher than that previously based on morphological identifications. Many lakes are permanently stratified, such as perennially ice-covered or saline meromictic, whereas shallow lakes in coastal regions are usually ice-free in summer, accounting for contrasting patterns in their phytoplankton temporal dynamics. Simple and short food webs are characteristicof Antarctic lakes, where phytoplankton fraction > 2 µm is usually dominated by nanoflagellates. In this review, we provide an overview of the current knowledge about phytoplankton of Antarctic lakes, including information on biodiversity (morphologicalbased, functional and molecular), and the main ecological aspects (colonization, endemism, ecological strategies, temporal dynamics, biotic interactions). We compared ecosystems of different trophic status and from Continental and Maritime Antarctica, including own data from manipulative experiments. Sat, 30 May 2020 00:00:00 GMT http://repositorio.unnoba.edu.ar/xmlui/handle/23601/478 2020-05-30T00:00:00Z http://repositorio.unnoba.edu.ar/xmlui/handle/23601/224 Shallow lakes from the Salado River basin (Buenos Aires, Argentina): effects of anthropogenic activities Las lagunas son los ecosistemas acuáticos predominantes en la región Pampeana, jugando un rol importante en las economías locales ya que proveen servicios ecosistémicos como el riego, el uso recreativo y la pesca. Estos cuerpos de agua se encuentran naturalmente enriquecidos en nutrientes (Quirós y Drago, 1999), aunque en los últimos años han comenzado a cambiar del estado eutrófico al hipereutrófico debido a las descargas de nitrógeno y fósforo relacionadas con actividades humanas (Portela et al., 2009). Además, estas lagunas se encuentran localizadas en las partes bajas del terreno, por lo que se encuentran afectadas por la escorrentía proveniente de la agricultura y por otros contaminantes (Vera et al., 2010), causando un deterioro general en la calidad del agua y en los servicios ecosistémicos. La cuenca del río Salado se encuentra en el centro de la región pampeana, una de las áreas más productivas de la Argentina. Los ambientes acuáticos asociados a esta cuenca se encuentran fuertemente afectados por una alta heterogeneidad en el uso del suelo. En particular, la cuenca alta se caracteriza por el uso agrícola (rotaciones de soja-maíz-trigo) con altos requerimientos de agroquímicos; mientras que la cuenca baja se caracteriza por la ganadería y pasturas (Gabellone et al., 2005). Estas diferencias entre cuencas afectan a la composición de las comunidades de fitoplancton (Sánchez et al., 2021) y bacterioplancton (Nuozzi et al., in prep). En este trabajo, nuestro principal objetivo fue caracterizar el uso del suelo en las áreas circundantes a diversos lagos de la cuenca del río Salado, con el fin de desentrañar su efecto en la calidad del agua y el estado sanitario de estos cuerpos de agua.; Shallow lakes are the predominant aquatic ecosystems in the Pampa Region, playing an important role in local economies by providing ecosystem services such as irrigation, recreation and fishing. These water bodies are naturally enriched in nutrients (Quirós and Drago, 1999), although in the last years some have begun to change from a eutrophic to hypertrophic state due to nitrogen and phosphorus discharges related to human activities(Portela et al., 2009). Besides, these lakes are located in a lowland river basin, so they are affected by runoff from agriculture and other pollutants(Vera et al., 2010), causing an overall deterioration in water quality and ecosystem services.The Salado River basin is located in the centre of the Pampa Region, one of the most productive areas of Argentina. The aquatic environments associated with this basin are strongly affected by a high heterogeneity in land use. In particular, the upper basin is characterized by agricultural use (soybean-corn-wheat rotations) with high requirements of agrochemicals; while the lower basin is characterized by livestock and pastures(Gabellone et al., 2005). These differences between basins affect the phytoplankton (Sánchez et al., 2021) and bacterioplankton (Nuozzi et al.,in prep.) community compositions. Here, our main objective was to characterize land use in the areas surrounding shallow lakes throughout the Salado River basin, in order to disentangle its effect on water quality and sanitary state of these waterbodies. Thu, 01 Jul 2021 00:00:00 GMT http://repositorio.unnoba.edu.ar/xmlui/handle/23601/224 2021-07-01T00:00:00Z http://repositorio.unnoba.edu.ar/xmlui/handle/23601/134 Covariation patterns of phytoplankton and bacterioplankton in hypertrophic shallow lakes The aim of this work was to assess the temporal patterns in the community composition of phytoplankton (PCC) and bacterioplankton (BCC) in two interconnected and hypertrophic Pampean shallow lakes (Argentina). Factors shaping their community dynamics and community temporal covariations were also analysed. We performed 4 years of seasonal samplings (2012-2016) and communities were studied by Utermöhl approach (PCC) and Illumina MiSeq sequencing (BCC). We found marked seasonal variations in both communities, and inter-annual variations with decreasing microbial community similarities along the study. We also observed covariation in community-level dynamics among PCC and BCC within- and between-shallow lakes. The within-lake covariations remained positive and significant, while controlling for the effects of intrinsic (environmental) and extrinsic (temporal and meteorological) factors, suggesting a community coupling mediated by intrinsic biotic interactions. Algal-bacterial associations between different taxa of phytoplankton and bacterioplankton within each lake were also found. PCC was mainly explained by pure regional extrinsic (17-21%) and intrinsic environmental (8-9%) factors, while BCC by environmental (8-10%) and biotic interactions with phytoplankton (7-8%). Our results revealed that the influence of extrinsic regional factors can be channeled to bacterioplankton through both environmental (i.e. water temperature) and phytoplankton effects. Thu, 20 Aug 2020 00:00:00 GMT http://repositorio.unnoba.edu.ar/xmlui/handle/23601/134 2020-08-20T00:00:00Z