The deal was completed Saturday during the NHL draft in St. Paul, Minn.
The 26-year-old Gervais had six assists in 53 games last season with the Islanders. In 331 career NHL games, all with New York, the Quebec native has nine goals and 59 assists.
Gervais was a sixth-round pick - No. 192 overall - by the Islanders in the 2003 draft.
In 134 AHL games with the Bridgeport Sound Tigers, Gervais had 25 goals and 47 assists.