Using satellites to map land cover helps scientists understand life on Earth and how humans alter ecosystems. When sunlight hits the Earth’s surface, some of the light bounces back into space. Different land surfaces, such as forests, bare ground, roads, and water, reflect different wavelengths of the sunlight differently. Satellites measure the reflected radiation to image distinct land features, as illustrated in the August 2004 Bio Viz Congo Land Cover.
AMNH ichthyologists Melanie Stiassny and Bob Schelly are examining the distribution of closely related fish species in the lower Congo River in west-central Africa. They hypothesize that physical barriers in the river may have led to the evolution of new species. Stiassny and Schelly have noted that several fish species in the genus Lamprologus occupy distinct portions of the river. Scientists at the American Museum of Natural History and the University of Georgia are using object-oriented analysis to map the river channel via satellite to discover if regions of whitewater have acted as a barrier to fish movement over tens of thousands of years, thus allowing species to diverge. If such barriers coincide with the ranges of fish species, it will show that the mapping techniques featured in this visualization can be used to understand fish evolution, habitat conservation, and other ecological questions in river basins worldwide.