NEW ORLEANS — The manatees that grazed in Lake Pontchartrain before Hurricane Katrina haven't been seen since, but eight dolphins were leaping in the lake this week.

"If the big critters are back, the lake is definitely coming back," Carlton Dufrechou, executive director of the Lake Pontchartrain Basin Foundation, said yesterday.

Flocks of pelicans and the pod of dolphins spotted Monday indicate that there are fish for them to eat, he said.

Earlier in the week, the journal Environmental Science & Technology reported that tests had found the dirty floodwaters pumped out of the city may be a long-term hazard to wildlife.

"We knew Pontchartrain would heal itself," but the rate at which it seems to be doing so is a welcome surprise, Dufrechou said.

Dufrechou said the last reported manatee sighting was about a week before the hurricane, but he added that there haven't been any sightings of dead manatees, either.

"I would suggest that means nature took care of itself — they knew something big was up and got out of Dodge," Dufrechou said.

Meanwhile, the New Orleans aquarium, which lost the majority of its collection during Katrina, brought back its 300-pound sea turtle, King Midas.

About 10,000 animals died after four days without support systems at the Audubon Aquarium of the Americas.

The survivors, including a penguin colony, two sea otters and several hundred freshwater fish, were evacuated to other aquariums.

King Midas was brought back from Moody Gardens in Galveston, Texas, as the New Orleans aquarium began the process of repopulating its tanks.

"It's really a sign of hope and rebuilding. It was a big rallying point for our staff. They've gone through so much, losing animals they worked with for 20-plus years," aquarium spokeswoman Melissa Lee said.