Limnology, in particular eutrophication processes of tropical high mountain lakes in Ecuador. Ecology of high Andean streams.
(German Research Foundation, German Federal Ministry of economic Cooperation and Development).
Assessment of quality of water and eutrophication tendency of high-altitude tropical lakes, as they occur in the high Andes of South America, was previously hardly possible because there are no sufficient studies on ecology of these waters. Extremely high levels of UV radiation and missing seasons cause that these waters cannot be compared with waters of the temperate climate zone.
In cooperation with the Escuela Politecnica Nacional de Quito, Ecuador and the Pontificia Universidad Catolica del Ecuador, the San Pablo Lake, a cold (up to 20 ° C) high mountain lake, located directly on the equator, and its tributary, Rio Itambi, were investigated. The Lagos San Pablo is 600 ha and 35 m deep and is located at 2,700 m above sea level. The inflow takes place over a stream, which drains the surrounding mountain watershed with a height of up to 4,000 m.
Lago San Pablo
The results show that the lake is monomictic with a stratification phase from October to June with only about 2 ° C temperature difference, the epilimnion is 15 m thick and is characterized by nocturnal cooling processes. Nocturnal convergence flows occur and lead to a regular partial mixing of the lake, the so-called atelomixis. Here, a part of the phytoplankton population is shifted to the non-illuminated aphotic zone.
Phosphorus is present in high concentrations in the epilimnion (0.14-0.25 mg / L SRP) year-round.
Depending on altitude, structure of the rivers in Ecuador varies greatly, although the high-altitude waters (2,500 to 4,500 m) have so far hardly been recorded and described ecologically. Data on ecological zonation and hydrological structure, however, form the basis for any monitoring of the waters.
Catchment area, water structure and chemical and biological dynamics of Rio Itambi, a typical Andean highland river, have been studied to deepen knowledge of biology of highland waters and to establish a system of river zonation. Essential parameters for the formation of the biocoenosis are the low oxygen concentrations, the lack of allochthonous entry and the high dynamics of erosion associated with regular landslides.
Lago San Pablo