GULFPORT, Miss. — Two more dead dolphins have washed ashore in Mississippi, but scientists hope an ailing dolphin found in neighboring Alabama will provide answers about what is killing the marine mammals in the Gulf of Mexico.

Mobi Solangi, director of the Institute for Marine Mammal Studies, said the two dead dolphins washed ashore over a 24-hour period ending Sunday. A female dolphin washed ashore on the beach in Gulfport and the other was a male found on the beach in Pass Christian. Both dolphins were under the age of a year old and were badly decomposed.

Officials planned to take samples for testing, but they also are hoping to get answers about what it causing the deaths by testing a sickly dolphin found Wednesday in a marshy area of Fort Morgan, Ala. That dolphin was taken to Gulfport for treatment and to be studied in hopes of providing answers about the spike in dolphin deaths.

The 2-year-old male is the first to be found alive since a blown out well caused a massive oil spill last spring, Solangi said.

In a typical year, about 30 dead dolphins are found along Mississippi and Alabama beaches, Solangi said. There have been more than 100 over the course of the past year, he said. And more than 540 dolphins have died since February 2010, some three months before the BP oil spill began, when officials at the National Oceanic and Atmospheric Administration started documenting the unusual number of dolphin deaths.

To date no definitive link has been made between the spill and the deaths, which in south Mississippi and Alabama are three to four times what they are in a normal year.

"From a scientific standpoint, this is a very significant event," Solangi said of the dolphin being found alive. He said two dead dolphins were found within a few miles of the survivor.

A total of five dolphins have now washed ashore along beaches in South Mississippi and Alabama in the last week.

"So much is unknown or lost when you're testing necrotic tissue rather than tissue from a live animal," he said. "We're hoping this will bring us closer to solving the puzzle, give us some better answers."

Biologists have speculated that the millions of gallons of crude oil that spilled into the Gulf, and the subsequent applications of dispersants, may have affected the immune systems of marine animals such as dolphins and turtles.

People who found the survivor dolphin tried to gently push him back into the water, but it kept beaching itself, Solangi said. That is when the institute was contacted and transportation arrangements were made. The animal arrived dehydrated with cuts, bruises and parasites. It is being treated with antibiotics and liquids.

Blood and tissue samples have been taken, and were to be sent Monday to NOAA facilities around the country for testing.

As for the dolphin, Solangi gives it a 50-50 chance of survival.

"He's in guarded condition," Solangi said. "We've got him on 24-7 watch."