Animal migrations, which are one of the most remarkable spectacles of nature, can strongly influence ecological processes by transferring large amounts of carbon, nitrogen, and other important nutrients among ecosystems. The Mara River in East Africa supports the largest remaining overland mammal migration in the world with seasonal visits of 1.3 million wildebeest, as well as resident population of over 4000 hippopotami who move daily between terrestrial and aquatic habitats. The Mara River is one of the few remaining rivers heavily influenced by large wildlife populations and provides a unique opportunity for understanding the influence of large animals on rivers. She will present findings from their project exploring the influence of hippos and wildebeests on river biogeochemistry in the Mara. Our findings demonstrate that wildebeest and hippopotamus insputs of carbon and nutrients influnvr river primary production, nutrient cycling, and whole-ecosystem metabolism. We suggest that these types of phenomena may have been more widespread throughout Africa before hippopotamus populations were reduced, and throughout the world prior to the virtual elimination of migratory large animals such as the American bison.