Estudio de los riesgos sanitarios para las aves acuáticas asociados con el abastecimiento de las Tablas de Daimiel y otros humedales manchegos con aguas residuales tratadas

Programa de investigación en la Red de Parques Nacionales: convocatoria 2009-2012.-- et al.La escasez de agua en la cuenca alta del río Guadiana ha hecho que se valore el uso de de las aguas residuales depuradas para la conservación de la biodiversidad de humedales como Las Tablas de Daimiel. En este trabajo hemos abordado el estudio de: (1) el riesgo que suponen las aguas residuales para aumentar la presencia de enteropatógenos en el medio y en las aves; (2) las condiciones ambientales que favorecen la presencia de Clostridium botulinum en el medio y la aparición de brotes de botulismo, incluyendo estudios experimentales y de campo; y (3) el papel de los invertebrados acuáticos, los dípteros necrófagos y las propias aves en la expansión los brotes de botulismo. La presencia de Escherichia coli patogénica aviar (APEC), Clostridium perfringens tipo A y C. botulinum tipo C/D ha sido generalmente mayor en muestras de agua, sedimento y heces de aves de las lagunas que reciben directamente aguas residuales (Navaseca y Veguilla) respecto a las Tablas de Daimiel. La aparición de un brote de botulismo en Navaseca en verano de 2010 estuvo asociado con una bajada del potencial redox, clorofila y sulfatos en el agua, de la DBO5 en sedimento y con un aumento del carbono inorgánico en el medio. Las condiciones de anoxia generadas, posiblemente asociadas con una proliferación de Lemna en la laguna, favorecieron la proliferación de C. botulinum. En muestreos previos a brotes de botulismo la mayor presencia de C. botulinum fue detectada en heces de aves, para después ser detectada en muestras de sedimento, agua, gasterópodos acuáticos, invertebrados acuáticos, moscas necrófagas y sus larvas. La muerte por cualquier motivo (p.e. infecciones por enterobacterias) de aves acuáticas con C. botulinum en su tracto digestivo actuaría como detonante de los brotes al servir el cadáver como medio de crecimiento de la bacteria y proliferación de larvas de mosca acumuladoras de toxina que pueden ser ingeridas por otras aves. Además se ha comprobado experimentalmente que las moscas son capaces de transportar C. botulinum a cadáveres exentos previamente de la bacteria, dando lugar así a larvas tóxicas que pueden iniciar el ciclo cadáver-larva-ave que magnifica los brotes de botulismo. Las aves afectadas por botulismo pueden excretar C. botulinum más de 2 semanas después del ingreso en los centros de recuperación para su tratamiento, por lo que el papel de las aves en la dispersión de la bacteria durante los brotes puede ser importante. En conclusión, los humedales abastecidos con aguas residuales podrían actuar como trampas ecológicas para las aves acuáticas por el riesgo de exposición a enteropatógenos y brotes de botulismo.I. Anza es becaria predoctoral con una beca I3P del CSIC, D. Vidal ha tenido un contrato post-doctoral I3P del CSIC, S. Díaz ha tenido una beca predoctoral de la JCCM y S. Sánchez ha tenido una beca post-doctoral de la JCCM. Este proyecto ha sido financiado por el OAPN (ref 35/2009).Peer Reviewe

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Eutrophication and bacterial pathogens as risk factors for avian botulism outbreaks in wetlands receiving effluents from urban wastewater treatment plants

Due to the scarcity of water resources in the >Mancha Húmeda> Biosphere Reserve, the use of treated wastewater has been proposed as a solution for the conservation of natural threatened floodplain wetlands. In addition, wastewater treatment plants of many villages pour their effluent into nearby natural lakes. We hypothesized that certain avian pathogens present in wastewater may cause avian mortalities which would trigger avian botulism outbreaks. With the aim of testing our hypothesis, 24 locations distributed in three wetlands, two that receive wastewater effluents and one serving as a control, were monitored during a year. Sediment, water, water bird feces, and invertebrates were collected for the detection of putative avian pathogenic Escherichia coli (APEC), Salmonella spp., Clostridium perfringens type A, and Clostridium botulinum type C/D. Also, water and sediment physicochemical properties were determined. Overall, APEC, C. perfringens, and C. botulinum were significantly more prevalent in samples belonging to the wetlands which receive wastewater. The occurrence of a botulism outbreak in one of the studied wetlands coincided with high water temperatures and sediment 5-day biochemical oxygen demand (BOD5), a decrease in water redox potential, chlorophyll a, and sulfate levels, and an increase in water inorganic carbon levels. The presence of C. botulinum in bird feces before the onset of the outbreak indicates that carrier birds exist and highlights the risk of botulinum toxin production in their carcasses if they die by other causes such as bacterial diseases, which are more probable in wastewater wetlands.This study was supported by the Spanish Ministry of Environment (grants OAPN 035/2009). I. Anza was supported by a JAE PRE grant from Spanish Council of Research (CSIC); D. Vidal was supported with a JAE DOC contract from the CSIC; and S. Díaz-Sánchez held a Ph.D. research grant funded by the Junta de Comunidades de Castilla—La Mancha (JCCM) (AG07). S. Sánchez acknowledges the Consejería de Educación y Ciencia de la Junta de Comunidades de Castilla—La Mancha and Fondo Social Europeo for his research fellowship (09/02-C).Peer Reviewe

Environmental controls, composition, structure, and typology of microbial mats in temporary salt lakes of the mancha húmeda biosphere reserve (central Spain)

Temporary shallow lakes (lagunas) of the Mancha Húmeda Biosphere Reserve are unbeatable natural labs for the study of microbial mats. Different types of these communities have been observed in them; besides, microbial mats are the dominant communities in some lagunas. The aim of this study is to quantify the factors involved in the formation of microbial mats in inland salt lakes under variable environmental conditions (i.e. substrate, hydroperiod, water ionic concentration and composition, and available nutrients). Special focus is made on the analyisis of correspondences between microorganisms? assemblages and specific combination of environmental conditions. Studied communities are located in 10 fluctuating lagunas of the Mancha Húmeda Biosphere Reserve. Twelve sampling campaigns were done along a hydrological year; environmental factors studied were temperature, water level, turbidity, conductivity, pH, major ions, soluble reactive phosphorus, nitrate, ammonium, and sediment granulometry. Microbial mat thickness, structure, and within-site spatial distribution were recorded in situ. Dominant components of the mat and the relative frequency of the different morphological patterns were determined after observation with an Olympus BH-2 optical microscope of samples previously collected. Multivariate techniques were used to identify the most informative variables in terms of the type, function, and development of microbial mats, and relationships between hydrochemistry and sediment descriptors which are most relevant for microbial mat communities. Nitrate concentration in water discriminated best between different types of microbial mats. Nitrate concentration was highest in lagunas with thin and weak mats, ranging from 0.37-18.49 mg L-1, which correspond to hypereutrophic lagunas. Undetectable to 0.54 mg NO3- L-1 was found in lagunas with compact mats and in lagunas without mats. No significant differences in salinity were found between lagunas with different types of microbial mats, but magnesium-sulphate ionic composition predominates in compact-mats lagunas, whereas sodium-chloride waters are associated to weak and thin mats

Geodivulgar: Geología y Sociedad

Depto. de Geodinámica, Estratigrafía y PaleontologíaDepto. de Química InorgánicaDepto. de Didáctica de las Ciencias Experimentales , Sociales y MatemáticasFac. de Ciencias GeológicasFac. de Ciencias QuímicasFac. de EducaciónFALSEsubmitte