Tortorella moved past Bob Johnson to become the winningest American-born NHL coach with 235 victories. He left after the game without speaking to reporters due a personal matter.
"I think it was certainly satisfying for our players," Tampa Bay assistant coach Mike Sullivan said. "We've worked extremely hard over the past six or seven or eight games, maybe even longer, and haven't got rewarded."
Bill Guerin, Ruslan Fedotenko, Ben Walter and Mike Comrie scored for the Islanders, who have lost five of six. New York fell to 13th in the Eastern Conference, eight points behind eighth-place Philadelphia, which lost 4-3 to Toronto in overtime.
"When it rains, it pours," Guerin said. "We're down a bunch of guys right now. Our young guys have stepped in and played well, but we need more depth. It's nobody's fault. It just happened."
The Islanders have five players on injured reserve, and several others, including defenseman Brendan Witt, playing hurt.
"We're real fragile right now," coach Ted Nolan said. "We've got so many guys out. So many new guys. Everybody is trying the best they can. It seems like we're fighting an uphill battle."
New York goalie Rick DiPietro allowed eight goals on 44 shots.
Ouellet put the Lightning ahead 1-0 with a power-play goal at 6:51 of the first. Halpern stole the puck from DiPietro behind the net and passed to Ouellet in the low right circle.
Lecavalier made it 2-0 during a 5-on-3 power play with 7:51 left in the first.
Guerin cut the Islanders' deficit to 2-1 at 17:05 of the first. New York tied it at 2 on Fedotenko's goal at 4:16 of the second.
Halpern put Tampa Bay up 3-2 nine minutes into the second. Mathieu Darche skated in from the left wing, drew DiPietro toward him, then skated behind the net and found Halpern all alone in the low right circle. The Lightning took a 4-2 advantage when Tarnasky scored his first goal in 16 games with 5:11 left in the second.
Lecavalier jammed a puck past DiPietro at 4:58 of the third to extend the Lightning lead to 5-2. After Walter scored a power-play goal with 9:58 left, Lecavalier completed his hat trick from the right circle at 17:43. Ouellet, at 18:15, and Ward 10 seconds later made it 8-3.
"It seemed tonight, everything went in at once," Lecavalier said.
Comrie closed out the scoring with 36.4 seconds remaining.
DiPietro got his sixth assist of the season on Comrie's goal. It was his 13th overall, which moved him past Billy Smith for the most by a goalie in team history.
- DiPietro had allowed only two goals in winning the previous three games between the teams this season.
- Fedotenko left in the third with a left knee sprain after a collision in the Islanders' zone. He will be re-evaluated Wednesday.
- Islanders C Andy Hilbert hurt his ankle in warmups and didn't play.