Peru’s environmental agency is investigating the deaths of some 10,000 frogs whose bodies have been found in a river in the south of the country.
A small group of local people say that pollution in the River Coata is to blame for the deaths.
It says the government has ignored pleas for the construction of a sewage treatment plant in the area.
The Titicaca water frog is an endangered species that is found only in the huge freshwater lake shared by Peru and Bolivia and its tributaries.
Activists took about 100 dead frogs to the central square in the regional capital, Puno.
Peru’s National Forestry and Wildlife Service (Sefor) said it was investigating what happened.
The Titicaca water frog (Telmatobius culeus) has enormous folds of skin, which increase its surface area and help the amphibian absorb more oxygen from the surrounding air.
The frogs are endangered because humans have collected too many to eat. Their habitat is being lost and invasive species are taking over what remains of it.