Limnology of tropical mountain lakes: analysis of the hydromorphological, physical and biogeochemical variability of the cajas massif lake district
- Autores: Pablo V. Mosquera
- Directores de la Tesis: Jordi Catalan Aguilà (dir. tes.), Marisol Felip Benach (tut. tes.)
- Lectura: En la Universitat de Barcelona ( España ) en 2023
- Idioma: inglés
- Tribunal Calificador de la Tesis: Ruben Sommaruga (presid.), Lluís Camarero Galindo (secret.), Carlos A. Rivera Rondón (voc.)
- Programa de doctorado: Programa de Doctorado en Ecología, Ciencias Ambientales y Fisiología Vegetal por la Universidad de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TESEO
- Resumen
High-mountain tropical lakes in the South American continent are located in the upper part of the Andes range in the equatorial zone (Venezuela, Colombia, Ecuador, Peru, and Bolivia), altitudinally, usually above the forest line (3000-5000 m a.s.l.). They are generally in remote areas, which makes them comparable with other mountainous lake areas of the planet. They play an essential role in the hydrology of the tropical Andean zones, regulating the flow and water availability, being a vital source of drinking water, irrigation, and hydroelectricity, and supplying water to significant effluents of the Amazon River and rivers of the Pacific Ocean coast. The development of tropical limnology has been slow; priority has been given to studying large rivers such as the Amazon and its peripheral lagoons, partly due to their exceptional biotic richness. Long-term studies are not common in tropical regions despite the number of existing lakes that constitute a significant proportion of the world¿s freshwater resources. The limnology of high-mountain tropical lakes has been relegated even though most of these systems are located in natural reserve areas. The relatively few studies show that the limnology of tropical lakes differs from those of temperate zones. The main objective of this thesis is to broaden the knowledge of tropical limnology of the high-mountain lakes of the southern Andes of Ecuador through the study of their morphometric characteristics, the chemical variation of the water, and the mixing processes. The thesis results show that the lake abundance distribution of the Cajas Massif is similar to that found in other high mountain districts of glacial origin, differing at both ends of a power law relationship. The deviations for large lakes could be attributed to the space restriction that the altitude imposes in mountain ranges, and, for small lakes, it can be due to many of them already being filled in over time. One of the consequences of this skewed distribution is that most of the lentic water surface is found in medium-sized lakes and not in shallow lakes and pools. The lake water chemistry is remarkably variably in the area studied, including ionic composition, dissolved organic matter, and metals. The high variation is primarily due to complex overlapping of different volcanic lithologies in the catchments. The chemical diversity is comparable to that of European mountains with complex lithology. The variety of aquatic chemical niches in small territories could foster species richness. The lakes of the Cajas Massif show primarily warm monomictic mixing regimes and not annual polymixis, as traditionally suggested for these lakes. Polymyxis occurs only during a limited period of the year (2-3 months) and more permanently in the highest lakes (~4,000 m a.s.l.). The results obtained in this thesis can likely represent other lake districts of the Andean range.
