Thrashers make three deals at deadline
The Thrashers also traded goalie Drew MacIntyre to the Montreal Canadiens for defenseman Brett Festerling and sent veteran forward Freddy Modin to the Calgary Flames for a seventh-round pick in this year's draft.
Thrashers general manager Rick Dudley also claimed forward Rob Schremp off waivers from the New York Islanders and signed defenseman Mark Stuart to a three-year contract extension. The Thrashers acquired Stuart and center Blake Wheeler from Boston on Feb. 18 for center Rich Peverley and defenseman Boris Valabik.
Schremp has 10 goals and 12 assists in 45 games this season with the Islanders.
Dvorak, who had seven goals and 21 points for the Panthers, can be an unrestricted free agent after the season. Bergfors is a pending restricted free agent.
Bergfors has 29 points, including 11 goals, for Atlanta. He has 74 points in 142 career games with Atlanta and New Jersey.
Rissmiller played in only one game with Atlanta this season.
Atlanta also received a fifth-round pick in this year's draft in the trade with Florida.
Modin, 36, had 10 points, including seven goals, in 36 games this season. He signed with Atlanta as a free agent on Sept. 6, 2010. In his NHL career, he has 232 goals and 230 assists with Toronto, Tampa Bay, Columbus, Los Angeles and Atlanta.
Modin was signed by the Thrashers as a free agent on Sept. 6, 2010.
MacIntyre and Festerling have spent most of the season in the AHL.
Festerling, 24, has 16 points, including three goals, for Syracuse and Hamilton. He also played in one game with Montreal. During the 2008-09 season, Festerling had eight assists in 83 NHL games with Anaheim.
MacIntyre was 12-5-1 with a 2.91 goals-against average for Chicago of the AHL. He spent time on the Thrashers' roster this season but didn't play in a game.