Through natural processes, oxbow lakes usually have a limited life span before sediment build up transforms them into marshes and the subject of natural succession, or they become reconnected to the main river in times of flooding. Other threats are man made. The damming of rivers, flood defences and the diversion of rivers together with floodplain development has reduced the ability of rivers to "spread" out and find their natural course, over their natural floodplain.
Oxbow lakes increase biodiversity in rivers because they nourish many species that could not normally live in nearby rivers. When floods occur, there is often an exchange of species between the oxbow lakes and the main river channel.