OOS 2

Biodiversity of Temperate and Tropical Rivers in a Changing World: Research Frontiers and Future Challenges

Will temperate and tropical rivers become more variable in their species assemblages over the next century? How will adaptive traits likely determine future distributions of freshwater species? Are there general considerations that will help to anticipate changes? Explaining how different locations have especially high species diversity has remained a major goal in ecology. Given the increasing concerns over the loss of native species in many freshwater ecosystems and the consequences for changes in ecosystem processes, this symposium will compare how emerging differences can influence distinct species distributions in temperate and tropical rivers. Unlike most marine and terrestrial ecosystems, the biodiversity of rivers does not follow a general latitudinal pattern of increase in species richness tropical ecosystems. Regional differences in the ages, hydrology, geology, and size of drainage basins can explain many of differences that occur among rivers. High climatic variability in many Neotropical and temperate ecosystems will continue to result in prolonged droughts and extreme floods. This high variability in hydrology can drive speciation and influence sustainability of these distinct species assemblages. Recent studies demonstrate that macro- and micro-scale differences in river channel connectivity have resulted in isolation during some periods and increased connectivity among habitats during other periods. Consequently, rates of speciation can vary within a single watershed. New concepts are being generated regarding how complex terrestrial and riverine species interactions are affected by changing land uses and invasive species. These novel ecosystems are characterized by new species interactions that will likely change how native species that co-existed in the last 100 years will shift in their distributions and functional relationships.