Rusty red waters in Madagascar

Iron-rich sediment colors the red-orange waters of the Betsiboka River Delta in Madagascar in this image taken by an astronaut on the International Space Station on Sept. 30, 2023. The sediment can clog waterways in the delta’s estuarial environment, but it can also form new islands that become colonized by mangroves.

Despite its rusty color, this artery of water is important for biodiversity. Within the Betsiboka River Delta, the estuary supplies food, such as seagrasses, to the endangered green turtle and vulnerable dugong, or sea cow.