“Never has there been such a dark period as this,” said Ayse Yildirim, a Cumhuriyet columnist, who found out by accident that criminal charges had been lodged against her for reporting on a Kurdish baby killed by a police bullet at a protest.

In addition to Mr. Dundar and the 11 Cumhuriyet staff members in jail, the paper’s employees are fending off an estimated 100 other criminal cases against them on a variety of charges, such as offending Turkishness, the president or local officials; terrorism; and membership in the PKK.

“Now even publishing a not-nice picture of Erdogan would be trouble,” said one prominent journalist, who spoke only on condition of anonymity because she feared she would be arrested, as many of her colleagues have been. “Now we even have ministers calling us and saying, ‘Why did you run that picture of me? I don’t like the way it looks,’ ” she said.

Some of the most virulent attacks on independent-minded journalists have come from journalists in the pro-Erdogan press who are known by their colleagues as “hit men.” First they attack the target by name, then personally lobby with intimidated media owners or the government to have the person fired or jailed.

The most notorious — and effective — of such hit men is a television commentator and social media activist named Cem Kucuk, a nationalist who many journalists say is really a government operative. When a New York Times journalist telephoned to arrange an interview with him, his colleagues said he could more easily be reached at the president’s office.

Mr. Kucuk laughed about that comment, saying, “No, no, I’m very close to Erdogan.” He denied he was a presidential employee, but made no apologies for advocating the jailing of journalists he views as “traitors” and supporters of terrorists.

“I don’t care what they call me,” he said. “In all of Turkey, people like me.” As for the spectacle of so many Turkish journalists behind bars, he said, “They deserve it.”