Acknowledgement
First I would like to thank Ms.Nopaluet Jitsinetan, the director of The Office Academic Promotion and Registration, for giving me the opportunity to do an internship within the university. For me it was an experience to be in the internship and to study an interesting animal species. It also helped to get back my interest in ecological research and to have new plans for my future career. I also would like all the people that worked in the office of Faunagua in Cochabamba. With their patience and openness they created an enjoyable working environment. Furthermore I want to thank all the scientist and students, with whom I did the fieldwork. We experienced great things together and they have shown me a beautiful part of their country. At last I would like to thank the Aquatic Ecology and Water Quality Management Group, especially Dr. E. Peeters, to allow me to do this interesting internship