Research on the ecology of migratory fish species in Peru's Madre de Dios River, stemming from a 2005 MacArthur grant to the University of Florida, has caused Brazil's national government to temporarily halt dam construction downstream on the Madeira River. Though it is likely that the dams will eventually be constructed, the application of knowledge emerging from the MacArthur-supported research will influence the design of policies, practices, and structures, and thus mitigate the more destructive aspects posed by the dams. Brazilian President Luiz Inacio Lula da Silva recently met with project staff and expressed a commitment to reaching a science-based solution