Meandering river systems naturally mediate the flux of water, nutrients, and sediment through the landscape, attenuating floodwaters and filtering contaminants within the floodplain, while supporting a suite of floral and faunal species. However, the combined effects of climate change and land-use alteration will change the natural functioning of these environments, which will threaten the survival of riverine communities across the world.
Synonymous with meandering rivers are oxbow lakes – arcuate lakes formed by the termination of river bends as they collide into one another, or are bypassed by the river in favour of a shorter, steeper flow path. These lakes form specialist habitats for aquatic species and essential nutrient and contaminant filters, removing them from the river and burying them in the lake bed. Despite widespread knowledge of oxbow lakes as landforms, little is known about their physical and chemical characteristics, particularly in space and time.
To truly forecast how these aquatic systems will change in the future, we need to understand how they function now. Rivers in the Amazon Basin – particularly near the Andes mountain range in Bolivia – provide a unique opportunity for us to measure the physical and chemical characteristics of oxbow lakes in a relatively unaltered setting. Moreover, because these rivers evolve so quickly (migrating at 10s of metres per year, and creating oxbow lakes over annual to decadal timescales, we can observe the full evolutionary process; from inception to terrestrialisation, where the lake is completely filled and converted back to land.