Reconstrucción de las condiciones tróficas de Laguna Espejo (X Región de Los Lagos) mediante el uso de diatomeas y parámetros físicos-químicos contenidos en un perfil sedimentario.
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Date
2023
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Publisher
Universidad de Concepción
Abstract
Los sistemas lacustres son afectados por actividades antrópicas y por fenómenos del medio natural. Mediante el estudio de los registros sedimentarios (paleolimnología) podemos determinar las condiciones pasadas y el efecto de ambos eventos sobre los cuerpos de agua. Laguna Espejo, es un lago situado en la comuna de Futaleufú, al sur de Chile. En este lago se ha realizado un estudio paleolimnológico analizando registros fisicoquímicos y diatomológicos contenidos en un perfil sedimentario extraído del lago. Para este estudio se consideraron los primeros 50 cm del núcleo, que representan aproximadamente los últimos ~882 años. Los análisis de susceptibilidad magnética arrojaron un alza marcada en el año 1840, el cual se condice con la disminución de materia orgánica, carbonatos, nutrientes y pigmentos, lo que indicó la presencia de material volcánico en este punto. De acuerdo con la composición diatomológica se definieron 4 zonas a lo largo del perfil sedimentario, donde es posible observar un aumento de la abundancia relativa de especies Staurosirella pinnata y Brachysira liliana lo que indicarían una baja cantidad de nutrientes en el lago. Por el contrario, aumentos en especies como Staurosira construens, Discostella stelligera y Nitzschia denticula indicarían aguas ricas en nutrientes y un aumento de la productividad. El comportamiento del ensamble de diatomeas en relación a materia orgánica, nutrientes, sílice biogénica y pigmentos, permitió la reconstrucción del estado trófico de Laguna Espejo durante los últimos casi mil años.
Lake systems are affected by anthropogenic activities and natural phenomena. Through the study of sedimentary records (paleolimnology) we can determine past conditions and the effect of both events on water bodies. Laguna Espejo is a small lake located in Futaleufú town, southern Chile. A paleolimnological study has been carried out in this lake by analyzing physicochemical and diatomological records contained in a sedimentary profile extracted from the lake. For this study, the first 50 cm of the core were considered, representing approximately the last ~882 years. Magnetic susceptibility analyses showed a marked increase in the year 1840 AD, which is consistent with a decrease in organic matter, carbonates, nutrients and pigments, indicating the presence of volcanic material at this point. According to the diatomological composition, 4 zones were defined along the sedimentary profile, where it is possible to observe an increase in the relative abundance of Staurosirella pinnata and Brachysira liliana species, which would indicate a low amount of nutrients in the lake. On the contrary, increases in species such as Staurosira construens, Discostella stelligera and Nitzschia denticula would indicate nutrient-rich waters and increased productivity. The behavior of the diatom assemblage in relation to organic matter, nutrients, biogenic silica and pigments, allowed the reconstruction of the trophic state of Laguna Espejo during the last thousand year.
Lake systems are affected by anthropogenic activities and natural phenomena. Through the study of sedimentary records (paleolimnology) we can determine past conditions and the effect of both events on water bodies. Laguna Espejo is a small lake located in Futaleufú town, southern Chile. A paleolimnological study has been carried out in this lake by analyzing physicochemical and diatomological records contained in a sedimentary profile extracted from the lake. For this study, the first 50 cm of the core were considered, representing approximately the last ~882 years. Magnetic susceptibility analyses showed a marked increase in the year 1840 AD, which is consistent with a decrease in organic matter, carbonates, nutrients and pigments, indicating the presence of volcanic material at this point. According to the diatomological composition, 4 zones were defined along the sedimentary profile, where it is possible to observe an increase in the relative abundance of Staurosirella pinnata and Brachysira liliana species, which would indicate a low amount of nutrients in the lake. On the contrary, increases in species such as Staurosira construens, Discostella stelligera and Nitzschia denticula would indicate nutrient-rich waters and increased productivity. The behavior of the diatom assemblage in relation to organic matter, nutrients, biogenic silica and pigments, allowed the reconstruction of the trophic state of Laguna Espejo during the last thousand year.
Description
Tesis presentada para optar al título de Bióloga
Keywords
Lagos Chile Análisis, Sedimentos lacustres