A lake which thousands of Guatamalans depend on for food and transport is under threat.

Over the years, rubbish, sewage and dertilizers have polluted Lake Atitlan and its surrounding bay.

Now a dangerous algae has contaminated the waters, threatening to destroy not only the lake, but also the livelihoods of the people who rely on it.

Al Jazeera's David Mercer reports from Guatamala.