Lake Titicaca has recently become a crime scene. South America's largest lake, well known for its rich biodiversity, is home to 530 aquatic species, some of which are endemic.

These include the Titicaca water frog, a critically endangered species that is also known as the"scrotum frog" for its wrinkled, baggy skin.

Recently, about 10,000 of these frogs have been found floating belly up at the lake. Pollution is feared to be the cause, authorities said.

The lake's water quality has decreased significantly in recent years. Contamination by thousands of illegal mines along the lake is likely to blame, as they pass poisonous waste water into the lake and its tributary rivers.

The scrotum frogs are now the ones to suffer. Numbers for this entirely aquatic species have declined dramatically over past years. The International Union for Conservation of Nature Red List cites the frogs as critically endangered, as their numbers have fallen by 80 percent over the last 15 years.

The recent mass death has caused the Peruvian Forestry and Wildlife Service to launch an investigation. An environmental group brought the incident to the agency's attention by protesting in the lakeside city of Puno. The Committee Against the Pollution of the Coata River had brought 100 dead frogs to Puno to make a statement.

"I had to bring them the dead frogs," one of the activists said. "The authorities don't realize how we're living. They have no idea about how serious the pollution is. The situation is maddening."