"It might be the highest diversity of trout species on Earth," our guest Ulrich Eichelmann says of a suite of European rivers slated for damming to generate electricity – rivers which also host a vast wealth of birds, bats, bugs and beauty – plus a deep cultural heritage. Rapid biological surveys are a well known way to establish the richness of an ecosystem and advocate for their conservation, and a corps of scientists have used this conservation solution to repeatedly prove that the rush to build hundreds of new hydroelectric dams threatens to drown this heritage, with impressive results: A proposal to dam the last free-flowing river in Europe (the Vjosa) was halted in part on the basis of one such survey conducted by Scientists for Balkan Rivers which Eichelmann coordinates, after the team identified species new to science, in addition to great overall biodiversity. The group has since turned its focus to other threatened rivers in the region, and he describes their activities, plus which rivers' ecologies they are investigating now. Episode Artwork: The biodiversity of Balkan rivers is now becoming more widely known, and also their beauty, such as Kravice Waterfalls on the Trebižat river in Bosnia-Herzegovina. Photo by Goran Safarek for Riverwatch/EuroNatur. Please invite your friends to subscribe to the Mongabay Newscast wherever they get podcasts, or download our free app in the Apple App Store or in the Google Store to get access to our latest episodes at your fingertips. If you enjoy the Newscast, please visit www.patreon.com/mongabay to pledge a dollar or more to keep the show growing, Mongabay is a nonprofit media outlet and all support helps! See all our latest news from nature's frontline at Mongabay's homepage: news.mongabay.com or find us on Facebook, Twitter, and Instagram by searching for @mongabay. Please share your thoughts and feedback! submissions@mongabay.com.