The Marañón supports an enormous number of unique ecosystems. Isolated between the Andes Mountains, the Marañón has allowed for many species to evolve without interaction with other areas, which leads to extremely high levels of endemism in the valley. These species rely on the Marañón to survive.
Birdlife International lists the Marañón valley as urgently in need of protection; at least 10 of the bird species that live there in IUCN categories of critically endangered, endangered or vulnerable.
New species are regularly being discovered and scientists have shown that overall species diversity in the Marañón has been significantly under-estimated, highlighting the need for further study and immediate protection.