Streams that once sang with the croaks, chirps and ribbits of dozens of frog species have gone silent. They’re victims of a fungus that’s decimating amphibian populations worldwide. Such catastrophic declines have been documented for more than a decade, but until recently scientists knew little about how the loss of frogs alters the larger ecosystem. A new study has found that tadpoles play a key role keeping the algae at the base of the food chain productive.