This is part of "Ocean Shock," a Reuters series exploring climate change's impact on sea creatures and the people who depend on them.

A priest in a white robe swung an incense burner, leading the way for thousands of marchers as they crammed into a winding cobblestone alley decorated with candy-colored streamers in Lisbon's ancient Alfama neighborhood.

Behind the priest, six men carried a life-sized statue of St. Anthony, Lisbon's patron saint, born more than 800 years ago. The musky incense swirled together with the smoke from orange-hot charcoals grilling whole sardines a few streets away.