Acknowledgement First I would like to thank Dr. P. van Damme, the director of Faunagua, giving me the opportunity to do an internship within the organization. For me it was a unique experience to be in Bolivia 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. 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 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 Aqu ric Ecology and Water Quality Management Group, especially Dr. E. Peeters, to allow me to do this interesting internship.