It's in the water

What if hydrology is more important for predicting biodiversity than biology?bAn international team involving EPFL scientists has published research in the May 8th issue of the journal Nature that challenges current thinking about biodiversity and opens up new avenues for predicting how climate change or human activity may affect biodiversity patterns. Researchers from EPFL, Princeton University and the University of Maryland have demonstrated that the distribution of fish species in a river system can be accurately predicted with a simple method that uses only the geomorphology of the river network and rainfall measurements for the river system. The 3,225,000 km2 Mississippi-Missouri river basin covers all or part of 31 US states, spanning diverse habitat types and encompassing very different environmental conditions. The one thing linking all these habitats is the vast river network. Using geomorphological data from the US Geological Survey, the researchers identified 824 sub-basins in the network. In these, the simple presence (or not) of 433 species of fish was established from a database of US freshwater fish populations. Data on the average runoff production -the amount of rainfall that ends up in the river system and not evaporated back into the air - was then used to calculate the habitat capacity of each sub-basin.