A heron is pictured on the banks of Guanabara Bay, at the Niteroi port near Rio de Janeiro, Brazil, December 11, 2015. Before dawn one morning in August, two men disguised as fishermen hid in the dark outside the compound of oil service company on Rio de Janeiro's picturesque Guanabara Bay, the site of next year's Olympic sailing competition. When a pipe began oozing pungent liquid into the stagnant bay, they recorded images on camera and took a water sample. Picture taken on December 11, 2015. REUTERS/Ricardo Moraes