1. Department of Aquatic Ecology and Water Quality Management; Wageningen University; P.O. Box 47 Wageningen NL-6700 AA The Netherlands
2. Centre for Monitoring and Warnings of Natural Disasters; Cachoeira Paulista 12630-000 SP Brazil
3. Resource Ecology Group; Wageningen University; P.O. Box 47 Wageningen NL-6700 AA The Netherlands