Less than three months after Dean Singleton’s (left) MediaNews Group acquired the Mercury News, the newspaper announced today that it will lay off 101 employees — including 40 from its newsroom — due to declining advertising revenues. Publisher George Riggs said in an internal memo that he intends to have eliminated the jobs by Dec. 19.

Executive Editor Susan Goldberg (right) told KCBS-AM: “This is an economic layoff and it is because of the transformation our business is going through, as we go from a print on paper business, to an electronic dissemination of information business. You are seeing a lot of issues there as advertisers are also going more to the electronic media.”

The Merc is in the midst of contract negotiations with three unions. Riggs said that depending on the outcome of those talks, it is possible that “further expense reductions” might lower the number of layoffs.

Last November, the Merc reduced its staff through voluntary buyouts, which reduced the size of its newsroom by 52 people, from 332 to 280, according to Editor & Publisher. Assuming the newsroom still has 280 employees, the newest round of layoffs would cut the size of that department to 240 people.

[PPC, April 26, 2006: Singleton says no layoffs are planned at Merc. “Staffs go up, staffs go down … I can’t promise you they won’t go down.”] [Chronicle: Merc to cut 101 jobs]