A mangrove conservation project in Guanabara Bay has shown how a dying ecosystem can be transformed into a thriving sanctuary

With deep blue waters flanked by dramatic peaks, Guanabara Bay is the postcard view of Rio de Janeiro – but it is also one of Brazil’s most polluted coastal environments. Raw sewage and solid waste flow into the bay from surrounding cities, home to more than 8 million people. Cargo ships and oil platforms chug in and out of commercial ports, while dozens of abandoned vessels lie rotting in the water.

But at the head of the bay, between the cities of Itaboraí and Magé, the environment feels different. The air is purer, the waters are empty but for small fishing canoes, and flocks of birds soar overhead.