Biota: Providing often-overlooked connections among freshwater systems.

When we think about connections in and among aquatic systems, we typically envision clear headwater streams flowing into downstream rivers, river floodwaters spilling out onto adjacent floodplains, or groundwater connecting wetlands to lakes and streams. However, there is another layer of connectivity moving materials among freshwater systems, one with connections that are not always tied to down-gradient flows of surface waters and groundwater. These movements are those of organisms, key components of virtually every freshwater system on the planet. In their movements across the landscape, biota connect aquatic systems in often-overlooked ways.