Análisis exploratorio de la composición y diversidad de las comunidades bacterianas presentes en ríos de la zona centro sur de Chile
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Date
2024
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Universidad de Concepción
Abstract
Las bacterias son un componente fundamental de los ecosistemas acuáticos, estas participan activamente en los ciclos biogeoquímicos, forman parte de la cadena trófica e influyen significativamente en la calidad del agua. Por lo anterior, sumado a sus cortos tiempos de vida y alta sensibilidad con su entorno, varios grupos de investigación a nivel internacional han centrado sus esfuerzos en integrar las comunidades bacterianas en las campañas de monitoreo y seguimiento ambiental de ríos y lagos. Sin embargo, el conocimiento de líneas base con respecto a estas comunidades en ambientes naturales y sus interacciones con agentes externos es aún muy limitado, lo que dificulta su uso como bioindicadores. En esta tesis se analizaron las comunidades bacterianas planctónicas y sedimentarias presentes en siete ríos de la zona centro sur de Chile con el objetivo de conocer cómo se componen, qué diferencias existen entre comunidades de agua y de lecho, en qué condiciones ambientales habitan y qué influencia ejercen estas condiciones sobre las comunidades.
Se recolectaron muestras de agua y de lecho, en una única campaña de terreno, y se utilizó secuenciación genética de alto desempeño (HTS) para determinar la composición taxonómica de las comunidades bacterianas. Las condiciones ambientales en las que habitaban las bacterias se caracterizaron con datos de parámetros fisicoquímicos, de caudales y de usos de suelo, obtenidos de mediciones en terreno y también desde registros gubernamentales. El procesamiento de los datos genéticos, los análisis de la estructura de las comunidades, las comparaciones entre comunidades de agua y de lecho, la evaluación de la influencia de las condiciones ambientales y las pruebas estadísticas se realizaron en el entorno del lenguaje de programación libre R. La composición de las comunidades fue consistente con estudios previos y se reconocieron diferencias en composición y diversidad entre agua y lecho. Las comunidades de agua, pese a la variabilidad ambiental, fueron muy similares entre sí, la diversidad alfa de estas se correlacionó con el área de cuenca y la diversidad beta con variables espaciales y de calidad simultáneamente. Por el contrario, en lecho se observó gran disimilitud, lo que podría indicar mayor influencia de aspectos locales, pero no se detectaron correlaciones significativas con condiciones ambientales. Esta área de investigación muestra gran potencial de desarrollo, se espera que este trabajo pueda ser utilizado como sustento para futuros estudios.
Bacteria are a key component of aquatic ecosystems, they actively participate in biogeochemical cycles, they are part of the trophic chain and significantly influence water quality. Furthermore, due to their short lifespans and high sensitivity to their environment, several international research groups have focused their efforts on integrating bacterial communities in environmental monitoring of rivers and lakes. However, the knowledge of a baseline regarding these communities in natural environments and their interactions with external agents is still very limited. This makes their use as bioindicators difficult. In this thesis, the planktonic and sedimentary bacterial communities present in seven rivers in the south-central zone of Chile were analyzed in their composition, differences between water and riverbed communities and environmental conditions they face. Water and sediment samples were collected in a single field campaign, and high throughput sequencing (HTS) was used to determine the taxonomic composition of bacterial communities. The environmental conditions in which these communities thrived were characterized with data on physicochemical parameters, flows, and land use, obtained from field measurements and from government records. The processing of genetic data, analysis of the structure of the communities, comparisons between communities from water and riverbed, evaluation of the influence of environmental conditions and statistical tests were carried out in the R programming language environment. Observed composition of communities was consistent with previous studies and differences in composition and diversity between water and riverbed samples were identified. The water communities, despite the environmental variability, were very similar to each other, the alpha diversity of these was correlated with the basin area and the beta diversity with spatial and water quality variables simultaneously. On the contrary, great dissimilarity was observed in the riverbed samples, which could indicate a greater influence of local aspects, but no significant correlations with environmental conditions were detected. This area of research shows great potential for development, and it is expected that this work can support future lines of study.
Bacteria are a key component of aquatic ecosystems, they actively participate in biogeochemical cycles, they are part of the trophic chain and significantly influence water quality. Furthermore, due to their short lifespans and high sensitivity to their environment, several international research groups have focused their efforts on integrating bacterial communities in environmental monitoring of rivers and lakes. However, the knowledge of a baseline regarding these communities in natural environments and their interactions with external agents is still very limited. This makes their use as bioindicators difficult. In this thesis, the planktonic and sedimentary bacterial communities present in seven rivers in the south-central zone of Chile were analyzed in their composition, differences between water and riverbed communities and environmental conditions they face. Water and sediment samples were collected in a single field campaign, and high throughput sequencing (HTS) was used to determine the taxonomic composition of bacterial communities. The environmental conditions in which these communities thrived were characterized with data on physicochemical parameters, flows, and land use, obtained from field measurements and from government records. The processing of genetic data, analysis of the structure of the communities, comparisons between communities from water and riverbed, evaluation of the influence of environmental conditions and statistical tests were carried out in the R programming language environment. Observed composition of communities was consistent with previous studies and differences in composition and diversity between water and riverbed samples were identified. The water communities, despite the environmental variability, were very similar to each other, the alpha diversity of these was correlated with the basin area and the beta diversity with spatial and water quality variables simultaneously. On the contrary, great dissimilarity was observed in the riverbed samples, which could indicate a greater influence of local aspects, but no significant correlations with environmental conditions were detected. This area of research shows great potential for development, and it is expected that this work can support future lines of study.
Description
Tesis para optar al grado académico de Magíster en Ciencias de la Ingeniería con mención en Ingeniería Civil
Keywords
Bacterias, Ríos