1. Resource Ecology Group; Wageningen University; P.O. Box 47 NL-6700 AA Wageningen The Netherlands
2. Aquatic Ecology and Water Quality Management Group; Wageningen University; P.O. Box 47 NL-6700 AA Wageningen The Netherlands
3. Department of Ecology; Centre for Biosciences; Federal University of Rio Grande do Norte; 59072-970 Natal Brazil
4. Department of Environmental Dynamics; National Institute for Research in the Amazon - INPA; 293669067-0375 Manaus Brazil