Biodiversity -- it's in the water

Top: runoff distribtion; Middle: sub-basin locations; Bottom: fish species distribution Click here for more information.

What if hydrology is more important for predicting biodiversity than biology" Research published in the May 8th issue of the journal Nature challenges current thinking about biodiversity and opens up new avenues for predicting how climate change or human activity may affect biodiversity patterns.

In the article, an international group of researchers demonstrates that the biodiversity 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 river network. Using geomorphological data from the US Geological Survey, the researchers – hydrologists from Princeton University and the EPFL in Lausanne, Switzerland, and biologists from the University of Maryland -- 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.