Understanding how the size of a river affects populations and communities is key to balancing human and environmental water needs. There are many components to river size, ranging from amount of flow to the number of branches, and these can be better understood and managed by developing relationships explaining how size changes affect river life.
Fish Futures Angus McIntosh and Jonathan Tonkin, along with their colleagues, outline how river size has important effects on the body size of predatory fish, and their movements and populations. Importantly, when rivers shrink or are shrunk by water withdrawal the reduced space and stressful conditions impair their food webs. Studying these processes will be valuable because these relationships apply generally, regardless of the river’s size. This research, especially developing generally-applicable river size relationships, can help identify harmful water management practices and point out the most effective ways to restore rivers.