Digital ad agency MRM Worldwide has been laying off some of its New York employees — about 15 over the past month and another five to 10 this week, according to ClickZ. The cuts span creative, account and project-management divisions. The layoffs come amid the most difficult year on record for online advertising. Many publishers expect display to decline more than 20 percent in the first quarter, and there are few signs that things will improve in the second quarter. Search is also starting to be affected by the weak economy: Most estimates point to an essentially flat first quarter for search. MRM, which is owned by Interpublic Group, has nine offices in the United States alone, and 2,500 employees worldwide.