Opponents of President Vladimir Putin had hoped to rally on the porch of the Culture Palace but city authorities closed the building, took away the porch's steps and spread dung around it, said Yelena Vasilyeva, local leader of the United Civil Front opposition movement.
"The stench was so strong you couldn't breathe, so only the most tenacious stayed," she said.
Dung was spread around a landmark building to fertilise the land, said a police spokesman in Murmansk, a city not far from Russia's borders with Norway and Finland.
Around 150 people braved the smell and carried on with the protest shouting "We need a different Russia" and "Out with Putin", Vasilyeva said.
The best defense is a good offense. This is certainly offensive.