“There are tremendously long lines to get into supermarkets,” which these days only accept dollars, said Katrin Hansing, an anthropologist at Baruch College in New York who spent much of the past year doing research in Havana. “The same can be said for medicine. There is nothing: There is no penicillin, there’s no antibiotics, there’s no aspirin. There’s nothing, really.”
On social media, videos of protesters decrying the lack of electricity and basic supplies circulated widely on Monday.
“I took to the streets because I’m tired of being hungry,” said Sara Naranjo, in a video shared on Twitter. “I don’t have water, I don’t have anything,” she said, adding, “you get bored, you get tired, you’re going crazy.”
Some observers called the mass demonstrations on Sunday inspiring, but also feared a crackdown, with Mr. Díaz-Canel calling on his supporters to take to the streets as well. Opposition groups reported that scores of activists were unaccounted for on Monday, fueling fear that security forces had taken a large number of demonstrators into custody.
Dissidents posted the names and photographs of several people they feared had been detained. Security forces in Cuba often take prominent activists into custody, or prevent them from leaving home during tense times, and videos circulating on social media showed the authorities patrolling the streets, violently detaining people.
But it was hard to ascertain the extent of a crackdown because internet connectivity was down in much of the island on Monday, a common tactic to suppress the ability of opponents to organize or even get basic information.
Some said the protests meant that Cubans had become increasingly emboldened to criticize their government, which typically puts down acts of dissent with ruthless efficiency.
“The basic economic situation is what’s pushing people to go out and raise their voices,” Ms. Hansing said. “But there’s also a loss of fear, and once that barrier is broken and more and more people see a significant number of people have lost their fear, more and more start getting encouraged.”