PORT FOURCHON, Louisiana (Reuters) - Scientists are examining samples from seven dolphins and over 100 sea turtles found dead along the U.S. Gulf Coast in the past two weeks to see if they were victims of the giant oil spill in the region, wildlife officials said on Thursday.
All of the deaths are being investigated as suspected casualties of the oil gushing unchecked since April 20 from a ruptured wellhead on the floor of the Gulf off Louisiana because of their proximity in time and space to the spill.
But none of the dolphins or turtles examined showed any obvious visible signs of oil contamination. Necropsies -- the animal equivalent of autopsies -- are being performed and analyzed to determine if oil ingestion caused the deaths.
"So far we have not seen any relationship with the deaths of either the turtles or the dolphins to oil," Dr. Moby Solangi, head of the Institute for Marine Mammal Studies, told Reuters TV in Gulfport, Mississippi.
But Solangi added it was only a matter of time before the spilled oil began affecting the dolphin population.
"This oil has spread into their habitat. There is no question that the oil is in their habitat," Solangi said.
The seven dolphins and 106 sea turtles were found along the coast of Louisiana, Mississippi and Alabama over the past two weeks, sources close to the Gulf's wildlife spill-response teams said.
One heavily decayed dolphin carcass was seen on the beach at the very tip of Port Fourchon in southeastern Louisiana. Gooey, rust-colored globs of oil debris began washing ashore on that beach on Wednesday night.
Solangi said dolphins were at the top of the aquatic food chain in the ocean and also acted like the 'canary in the coal mine,' in that their experience and behavior could give advance warning to humans of impending disasters and catastrophes.
A few of the deaths were ruled out as spill-related because they occurred before the spill or were animals that were known to have been sick or injured beforehand, the sources said.
Wildlife officials have expressed particular concern for the well-being of sea turtles in the Gulf following the spill because all five species that inhabit the region are endangered, and it is their spring nesting season.
But experts say large numbers of sea turtle deaths this time of year are not uncommon.
On a conference call with reporters on Wednesday, officials of the U.S. National Oceanic and Atmospheric Administration said it was still too early to draw firm conclusions from the latest wildlife casualties in the Gulf.
"We don't have definitive information for most of the ... (animals) that have been found," said Jane Lubchenco, Undersecretary of Commerce for Oceans and Atmosphere.
Impacts on bird life has been relatively light to date, according to wildlife specialists.
"So far, relatively few birds have been brought in with oil on their feathers," said David Ringer of the National Audubon Society, who put the number at between 12 and 20.
"The birds that have been brought in are birds that catch fish in open waters" and would have come in contact with oil there, he said.
Additional reporting by Deborah Gembara in Gulfport, Mississippi; Editing by Pascal Fletcher and Sandra Maler